diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -10,640 +10,7 @@
 #ifndef _LIBCPP_ALGORITHM
 #define _LIBCPP_ALGORITHM
 
-/*
-    algorithm synopsis
-
-#include <initializer_list>
-
-namespace std
-{
-
-template <class InputIterator, class Predicate>
-    constexpr bool     // constexpr in C++20
-    all_of(InputIterator first, InputIterator last, Predicate pred);
-
-template <class InputIterator, class Predicate>
-    constexpr bool     // constexpr in C++20
-    any_of(InputIterator first, InputIterator last, Predicate pred);
-
-template <class InputIterator, class Predicate>
-    constexpr bool     // constexpr in C++20
-    none_of(InputIterator first, InputIterator last, Predicate pred);
-
-template <class InputIterator, class Function>
-    constexpr Function          // constexpr in C++20
-    for_each(InputIterator first, InputIterator last, Function f);
-
-template<class InputIterator, class Size, class Function>
-    constexpr InputIterator     // constexpr in C++20
-    for_each_n(InputIterator first, Size n, Function f); // C++17
-
-template <class InputIterator, class T>
-    constexpr InputIterator     // constexpr in C++20
-    find(InputIterator first, InputIterator last, const T& value);
-
-template <class InputIterator, class Predicate>
-    constexpr InputIterator     // constexpr in C++20
-    find_if(InputIterator first, InputIterator last, Predicate pred);
-
-template<class InputIterator, class Predicate>
-    constexpr InputIterator     // constexpr in C++20
-    find_if_not(InputIterator first, InputIterator last, Predicate pred);
-
-template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator1  // constexpr in C++20
-    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
-             ForwardIterator2 first2, ForwardIterator2 last2);
-
-template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr ForwardIterator1  // constexpr in C++20
-    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
-             ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
-
-template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator1  // constexpr in C++20
-    find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
-                  ForwardIterator2 first2, ForwardIterator2 last2);
-
-template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr ForwardIterator1  // constexpr in C++20
-    find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
-                  ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
-
-template <class ForwardIterator>
-    constexpr ForwardIterator   // constexpr in C++20
-    adjacent_find(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class BinaryPredicate>
-    constexpr ForwardIterator   // constexpr in C++20
-    adjacent_find(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
-
-template <class InputIterator, class T>
-    constexpr typename iterator_traits<InputIterator>::difference_type  // constexpr in C++20
-    count(InputIterator first, InputIterator last, const T& value);
-
-template <class InputIterator, class Predicate>
-    constexpr typename iterator_traits<InputIterator>::difference_type // constexpr in C++20
-    count_if(InputIterator first, InputIterator last, Predicate pred);
-
-template <class InputIterator1, class InputIterator2>
-    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
-    mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
-
-template <class InputIterator1, class InputIterator2>
-    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
-    mismatch(InputIterator1 first1, InputIterator1 last1,
-             InputIterator2 first2, InputIterator2 last2); // **C++14**
-
-template <class InputIterator1, class InputIterator2, class BinaryPredicate>
-    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
-    mismatch(InputIterator1 first1, InputIterator1 last1,
-             InputIterator2 first2, BinaryPredicate pred);
-
-template <class InputIterator1, class InputIterator2, class BinaryPredicate>
-    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
-    mismatch(InputIterator1 first1, InputIterator1 last1,
-             InputIterator2 first2, InputIterator2 last2,
-             BinaryPredicate pred); // **C++14**
-
-template <class InputIterator1, class InputIterator2>
-    constexpr bool      // constexpr in C++20
-    equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
-
-template <class InputIterator1, class InputIterator2>
-    constexpr bool      // constexpr in C++20
-    equal(InputIterator1 first1, InputIterator1 last1,
-          InputIterator2 first2, InputIterator2 last2); // **C++14**
-
-template <class InputIterator1, class InputIterator2, class BinaryPredicate>
-    constexpr bool      // constexpr in C++20
-    equal(InputIterator1 first1, InputIterator1 last1,
-          InputIterator2 first2, BinaryPredicate pred);
-
-template <class InputIterator1, class InputIterator2, class BinaryPredicate>
-    constexpr bool      // constexpr in C++20
-    equal(InputIterator1 first1, InputIterator1 last1,
-          InputIterator2 first2, InputIterator2 last2,
-          BinaryPredicate pred); // **C++14**
-
-template<class ForwardIterator1, class ForwardIterator2>
-    constexpr bool      // constexpr in C++20
-    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
-                   ForwardIterator2 first2);
-
-template<class ForwardIterator1, class ForwardIterator2>
-    constexpr bool      // constexpr in C++20
-    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
-                   ForwardIterator2 first2, ForwardIterator2 last2); // **C++14**
-
-template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr bool      // constexpr in C++20
-    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
-                   ForwardIterator2 first2, BinaryPredicate pred);
-
-template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr bool      // constexpr in C++20
-    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
-                   ForwardIterator2 first2, ForwardIterator2 last2,
-                   BinaryPredicate pred);  // **C++14**
-
-template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator1      // constexpr in C++20
-    search(ForwardIterator1 first1, ForwardIterator1 last1,
-           ForwardIterator2 first2, ForwardIterator2 last2);
-
-template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr ForwardIterator1      // constexpr in C++20
-    search(ForwardIterator1 first1, ForwardIterator1 last1,
-           ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
-
-template <class ForwardIterator, class Size, class T>
-    constexpr ForwardIterator       // constexpr in C++20
-    search_n(ForwardIterator first, ForwardIterator last, Size count, const T& value);
-
-template <class ForwardIterator, class Size, class T, class BinaryPredicate>
-    constexpr ForwardIterator       // constexpr in C++20
-    search_n(ForwardIterator first, ForwardIterator last,
-             Size count, const T& value, BinaryPredicate pred);
-
-template <class InputIterator, class OutputIterator>
-    constexpr OutputIterator      // constexpr in C++20
-    copy(InputIterator first, InputIterator last, OutputIterator result);
-
-template<class InputIterator, class OutputIterator, class Predicate>
-    constexpr OutputIterator      // constexpr in C++20
-    copy_if(InputIterator first, InputIterator last,
-            OutputIterator result, Predicate pred);
-
-template<class InputIterator, class Size, class OutputIterator>
-    constexpr OutputIterator      // constexpr in C++20
-    copy_n(InputIterator first, Size n, OutputIterator result);
-
-template <class BidirectionalIterator1, class BidirectionalIterator2>
-    constexpr BidirectionalIterator2      // constexpr in C++20
-    copy_backward(BidirectionalIterator1 first, BidirectionalIterator1 last,
-                  BidirectionalIterator2 result);
-
-template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator2    // constexpr in C++20
-    swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2);
-
-template <class ForwardIterator1, class ForwardIterator2>
-    constexpr void                // constexpr in C++20
-    iter_swap(ForwardIterator1 a, ForwardIterator2 b);
-
-template <class InputIterator, class OutputIterator, class UnaryOperation>
-    constexpr OutputIterator      // constexpr in C++20
-    transform(InputIterator first, InputIterator last, OutputIterator result, UnaryOperation op);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator, class BinaryOperation>
-    constexpr OutputIterator      // constexpr in C++20
-    transform(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2,
-              OutputIterator result, BinaryOperation binary_op);
-
-template <class ForwardIterator, class T>
-    constexpr void      // constexpr in C++20
-    replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value);
-
-template <class ForwardIterator, class Predicate, class T>
-    constexpr void      // constexpr in C++20
-    replace_if(ForwardIterator first, ForwardIterator last, Predicate pred, const T& new_value);
-
-template <class InputIterator, class OutputIterator, class T>
-    constexpr OutputIterator      // constexpr in C++20
-    replace_copy(InputIterator first, InputIterator last, OutputIterator result,
-                 const T& old_value, const T& new_value);
-
-template <class InputIterator, class OutputIterator, class Predicate, class T>
-    constexpr OutputIterator      // constexpr in C++20
-    replace_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred, const T& new_value);
-
-template <class ForwardIterator, class T>
-    constexpr void      // constexpr in C++20
-    fill(ForwardIterator first, ForwardIterator last, const T& value);
-
-template <class OutputIterator, class Size, class T>
-    constexpr OutputIterator      // constexpr in C++20
-    fill_n(OutputIterator first, Size n, const T& value);
-
-template <class ForwardIterator, class Generator>
-    constexpr void      // constexpr in C++20
-    generate(ForwardIterator first, ForwardIterator last, Generator gen);
-
-template <class OutputIterator, class Size, class Generator>
-    constexpr OutputIterator      // constexpr in C++20
-    generate_n(OutputIterator first, Size n, Generator gen);
-
-template <class ForwardIterator, class T>
-    constexpr ForwardIterator     // constexpr in C++20
-    remove(ForwardIterator first, ForwardIterator last, const T& value);
-
-template <class ForwardIterator, class Predicate>
-    constexpr ForwardIterator     // constexpr in C++20
-    remove_if(ForwardIterator first, ForwardIterator last, Predicate pred);
-
-template <class InputIterator, class OutputIterator, class T>
-    constexpr OutputIterator     // constexpr in C++20
-    remove_copy(InputIterator first, InputIterator last, OutputIterator result, const T& value);
-
-template <class InputIterator, class OutputIterator, class Predicate>
-    constexpr OutputIterator     // constexpr in C++20
-    remove_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred);
-
-template <class ForwardIterator>
-    constexpr ForwardIterator    // constexpr in C++20
-    unique(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class BinaryPredicate>
-    constexpr ForwardIterator    // constexpr in C++20
-    unique(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
-
-template <class InputIterator, class OutputIterator>
-    constexpr OutputIterator     // constexpr in C++20
-    unique_copy(InputIterator first, InputIterator last, OutputIterator result);
-
-template <class InputIterator, class OutputIterator, class BinaryPredicate>
-    constexpr OutputIterator     // constexpr in C++20
-    unique_copy(InputIterator first, InputIterator last, OutputIterator result, BinaryPredicate pred);
-
-template <class BidirectionalIterator>
-    constexpr void               // constexpr in C++20
-    reverse(BidirectionalIterator first, BidirectionalIterator last);
-
-template <class BidirectionalIterator, class OutputIterator>
-    constexpr OutputIterator       // constexpr in C++20
-    reverse_copy(BidirectionalIterator first, BidirectionalIterator last, OutputIterator result);
-
-template <class ForwardIterator>
-    constexpr ForwardIterator      // constexpr in C++20
-    rotate(ForwardIterator first, ForwardIterator middle, ForwardIterator last);
-
-template <class ForwardIterator, class OutputIterator>
-    constexpr OutputIterator       // constexpr in C++20
-    rotate_copy(ForwardIterator first, ForwardIterator middle, ForwardIterator last, OutputIterator result);
-
-template <class RandomAccessIterator>
-    void
-    random_shuffle(RandomAccessIterator first, RandomAccessIterator last); // deprecated in C++14, removed in C++17
-
-template <class RandomAccessIterator, class RandomNumberGenerator>
-    void
-    random_shuffle(RandomAccessIterator first, RandomAccessIterator last,
-                   RandomNumberGenerator& rand);  // deprecated in C++14, removed in C++17
-
-template<class PopulationIterator, class SampleIterator,
-         class Distance, class UniformRandomBitGenerator>
-    SampleIterator sample(PopulationIterator first, PopulationIterator last,
-                          SampleIterator out, Distance n,
-                          UniformRandomBitGenerator&& g); // C++17
-
-template<class RandomAccessIterator, class UniformRandomNumberGenerator>
-    void shuffle(RandomAccessIterator first, RandomAccessIterator last,
-                 UniformRandomNumberGenerator&& g);
-
-template<class ForwardIterator>
-  constexpr ForwardIterator
-    shift_left(ForwardIterator first, ForwardIterator last,
-               typename iterator_traits<ForwardIterator>::difference_type n); // C++20
-
-template<class ForwardIterator>
-  constexpr ForwardIterator
-    shift_right(ForwardIterator first, ForwardIterator last,
-                typename iterator_traits<ForwardIterator>::difference_type n); // C++20
-
-template <class InputIterator, class Predicate>
-    constexpr bool  // constexpr in C++20
-    is_partitioned(InputIterator first, InputIterator last, Predicate pred);
-
-template <class ForwardIterator, class Predicate>
-    constexpr ForwardIterator  // constexpr in C++20
-    partition(ForwardIterator first, ForwardIterator last, Predicate pred);
-
-template <class InputIterator, class OutputIterator1,
-          class OutputIterator2, class Predicate>
-    constexpr pair<OutputIterator1, OutputIterator2>   // constexpr in C++20
-    partition_copy(InputIterator first, InputIterator last,
-                   OutputIterator1 out_true, OutputIterator2 out_false,
-                   Predicate pred);
-
-template <class ForwardIterator, class Predicate>
-    ForwardIterator
-    stable_partition(ForwardIterator first, ForwardIterator last, Predicate pred);
-
-template<class ForwardIterator, class Predicate>
-    constexpr ForwardIterator  // constexpr in C++20
-    partition_point(ForwardIterator first, ForwardIterator last, Predicate pred);
-
-template <class ForwardIterator>
-    constexpr bool  // constexpr in C++20
-    is_sorted(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class Compare>
-    constexpr bool  // constexpr in C++20
-    is_sorted(ForwardIterator first, ForwardIterator last, Compare comp);
-
-template<class ForwardIterator>
-    constexpr ForwardIterator    // constexpr in C++20
-    is_sorted_until(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class Compare>
-    constexpr ForwardIterator    // constexpr in C++20
-    is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void               // constexpr in C++20
-    sort(RandomAccessIterator first, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void               // constexpr in C++20
-    sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    void
-    stable_sort(RandomAccessIterator first, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    void
-    stable_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void                    // constexpr in C++20
-    partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void                    // constexpr in C++20
-    partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last, Compare comp);
-
-template <class InputIterator, class RandomAccessIterator>
-    constexpr RandomAccessIterator    // constexpr in C++20
-    partial_sort_copy(InputIterator first, InputIterator last,
-                      RandomAccessIterator result_first, RandomAccessIterator result_last);
-
-template <class InputIterator, class RandomAccessIterator, class Compare>
-    constexpr RandomAccessIterator    // constexpr in C++20
-    partial_sort_copy(InputIterator first, InputIterator last,
-                      RandomAccessIterator result_first, RandomAccessIterator result_last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void                    // constexpr in C++20
-    nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void                    // constexpr in C++20
-    nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last, Compare comp);
-
-template <class ForwardIterator, class T>
-    constexpr ForwardIterator                         // constexpr in C++20
-    lower_bound(ForwardIterator first, ForwardIterator last, const T& value);
-
-template <class ForwardIterator, class T, class Compare>
-    constexpr ForwardIterator                         // constexpr in C++20
-    lower_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
-
-template <class ForwardIterator, class T>
-    constexpr ForwardIterator                         // constexpr in C++20
-    upper_bound(ForwardIterator first, ForwardIterator last, const T& value);
-
-template <class ForwardIterator, class T, class Compare>
-    constexpr ForwardIterator                         // constexpr in C++20
-    upper_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
-
-template <class ForwardIterator, class T>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
-    equal_range(ForwardIterator first, ForwardIterator last, const T& value);
-
-template <class ForwardIterator, class T, class Compare>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
-    equal_range(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
-
-template <class ForwardIterator, class T>
-    constexpr bool                                    // constexpr in C++20
-    binary_search(ForwardIterator first, ForwardIterator last, const T& value);
-
-template <class ForwardIterator, class T, class Compare>
-    constexpr bool                                    // constexpr in C++20
-    binary_search(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                          // constexpr in C++20
-    merge(InputIterator1 first1, InputIterator1 last1,
-          InputIterator2 first2, InputIterator2 last2, OutputIterator result);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                          // constexpr in C++20
-    merge(InputIterator1 first1, InputIterator1 last1,
-          InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
-
-template <class BidirectionalIterator>
-    void
-    inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last);
-
-template <class BidirectionalIterator, class Compare>
-    void
-    inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last, Compare comp);
-
-template <class InputIterator1, class InputIterator2>
-    constexpr bool                                    // constexpr in C++20
-    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
-
-template <class InputIterator1, class InputIterator2, class Compare>
-    constexpr bool                                    // constexpr in C++20
-    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, Compare comp);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                          // constexpr in C++20
-    set_union(InputIterator1 first1, InputIterator1 last1,
-              InputIterator2 first2, InputIterator2 last2, OutputIterator result);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                          // constexpr in C++20
-    set_union(InputIterator1 first1, InputIterator1 last1,
-              InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                         // constexpr in C++20
-    set_intersection(InputIterator1 first1, InputIterator1 last1,
-                     InputIterator2 first2, InputIterator2 last2, OutputIterator result);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                         // constexpr in C++20
-    set_intersection(InputIterator1 first1, InputIterator1 last1,
-                     InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                         // constexpr in C++20
-    set_difference(InputIterator1 first1, InputIterator1 last1,
-                   InputIterator2 first2, InputIterator2 last2, OutputIterator result);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                         // constexpr in C++20
-    set_difference(InputIterator1 first1, InputIterator1 last1,
-                   InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                         // constexpr in C++20
-    set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
-                             InputIterator2 first2, InputIterator2 last2, OutputIterator result);
-
-template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                         // constexpr in C++20
-    set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
-                             InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
-    push_heap(RandomAccessIterator first, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
-    push_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
-    pop_heap(RandomAccessIterator first, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
-    pop_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
-    make_heap(RandomAccessIterator first, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
-    make_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
-    sort_heap(RandomAccessIterator first, RandomAccessIterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
-    sort_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr bool   // constexpr in C++20
-    is_heap(RandomAccessIterator first, RandomAccessiterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr bool   // constexpr in C++20
-    is_heap(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
-
-template <class RandomAccessIterator>
-    constexpr RandomAccessIterator   // constexpr in C++20
-    is_heap_until(RandomAccessIterator first, RandomAccessiterator last);
-
-template <class RandomAccessIterator, class Compare>
-    constexpr RandomAccessIterator   // constexpr in C++20
-    is_heap_until(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
-
-template <class ForwardIterator>
-    constexpr ForwardIterator        // constexpr in C++14
-    min_element(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class Compare>
-    constexpr ForwardIterator        // constexpr in C++14
-    min_element(ForwardIterator first, ForwardIterator last, Compare comp);
-
-template <class T>
-    constexpr const T&               // constexpr in C++14
-    min(const T& a, const T& b);
-
-template <class T, class Compare>
-    constexpr const T&               // constexpr in C++14
-    min(const T& a, const T& b, Compare comp);
-
-template<class T>
-    constexpr T                      // constexpr in C++14
-    min(initializer_list<T> t);
-
-template<class T, class Compare>
-    constexpr T                      // constexpr in C++14
-    min(initializer_list<T> t, Compare comp);
-
-template<class T>
-    constexpr const T& clamp(const T& v, const T& lo, const T& hi);               // C++17
-
-template<class T, class Compare>
-    constexpr const T& clamp(const T& v, const T& lo, const T& hi, Compare comp); // C++17
-
-template <class ForwardIterator>
-    constexpr ForwardIterator        // constexpr in C++14
-    max_element(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class Compare>
-    constexpr ForwardIterator        // constexpr in C++14
-    max_element(ForwardIterator first, ForwardIterator last, Compare comp);
-
-template <class T>
-    constexpr const T&               // constexpr in C++14
-    max(const T& a, const T& b);
-
-template <class T, class Compare>
-    constexpr const T&               // constexpr in C++14
-    max(const T& a, const T& b, Compare comp);
-
-template<class T>
-    constexpr T                      // constexpr in C++14
-    max(initializer_list<T> t);
-
-template<class T, class Compare>
-    constexpr T                      // constexpr in C++14
-    max(initializer_list<T> t, Compare comp);
-
-template<class ForwardIterator>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++14
-    minmax_element(ForwardIterator first, ForwardIterator last);
-
-template<class ForwardIterator, class Compare>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++14
-    minmax_element(ForwardIterator first, ForwardIterator last, Compare comp);
-
-template<class T>
-    constexpr pair<const T&, const T&>  // constexpr in C++14
-    minmax(const T& a, const T& b);
-
-template<class T, class Compare>
-    constexpr pair<const T&, const T&>  // constexpr in C++14
-    minmax(const T& a, const T& b, Compare comp);
-
-template<class T>
-    constexpr pair<T, T>                // constexpr in C++14
-    minmax(initializer_list<T> t);
-
-template<class T, class Compare>
-    constexpr pair<T, T>                // constexpr in C++14
-    minmax(initializer_list<T> t, Compare comp);
-
-template <class InputIterator1, class InputIterator2>
-    constexpr bool     // constexpr in C++20
-    lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
-
-template <class InputIterator1, class InputIterator2, class Compare>
-    constexpr bool     // constexpr in C++20
-    lexicographical_compare(InputIterator1 first1, InputIterator1 last1,
-                            InputIterator2 first2, InputIterator2 last2, Compare comp);
-
-template <class BidirectionalIterator>
-    constexpr bool     // constexpr in C++20
-    next_permutation(BidirectionalIterator first, BidirectionalIterator last);
-
-template <class BidirectionalIterator, class Compare>
-    constexpr bool     // constexpr in C++20
-    next_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
-
-template <class BidirectionalIterator>
-    constexpr bool     // constexpr in C++20
-    prev_permutation(BidirectionalIterator first, BidirectionalIterator last);
-
-template <class BidirectionalIterator, class Compare>
-    constexpr bool     // constexpr in C++20
-    prev_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
-
-}  // std
-
-*/
+// Synopsis available at http://wg21.link/algorithm.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/any b/libcxx/include/any
--- a/libcxx/include/any
+++ b/libcxx/include/any
@@ -10,75 +10,7 @@
 #ifndef _LIBCPP_ANY
 #define _LIBCPP_ANY
 
-/*
-   any synopsis
-
-namespace std {
-
-  class bad_any_cast : public bad_cast
-  {
-  public:
-    virtual const char* what() const noexcept;
-  };
-
-  class any
-  {
-  public:
-
-    // 6.3.1 any construct/destruct
-    any() noexcept;
-
-    any(const any& other);
-    any(any&& other) noexcept;
-
-    template <class ValueType>
-      any(ValueType&& value);
-
-    ~any();
-
-    // 6.3.2 any assignments
-    any& operator=(const any& rhs);
-    any& operator=(any&& rhs) noexcept;
-
-    template <class ValueType>
-      any& operator=(ValueType&& rhs);
-
-    // 6.3.3 any modifiers
-    template <class ValueType, class... Args>
-      decay_t<ValueType>& emplace(Args&&... args);
-    template <class ValueType, class U, class... Args>
-      decay_t<ValueType>& emplace(initializer_list<U>, Args&&...);
-    void reset() noexcept;
-    void swap(any& rhs) noexcept;
-
-    // 6.3.4 any observers
-    bool has_value() const noexcept;
-    const type_info& type() const noexcept;
-  };
-
-   // 6.4 Non-member functions
-  void swap(any& x, any& y) noexcept;
-
-  template <class T, class ...Args>
-    any make_any(Args&& ...args);
-  template <class T, class U, class ...Args>
-    any make_any(initializer_list<U>, Args&& ...args);
-
-  template<class ValueType>
-    ValueType any_cast(const any& operand);
-  template<class ValueType>
-    ValueType any_cast(any& operand);
-  template<class ValueType>
-    ValueType any_cast(any&& operand);
-
-  template<class ValueType>
-    const ValueType* any_cast(const any* operand) noexcept;
-  template<class ValueType>
-    ValueType* any_cast(any* operand) noexcept;
-
-} // namespace std
-
-*/
+// Synopsis available at http://wg21.link/any.synop.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/array b/libcxx/include/array
--- a/libcxx/include/array
+++ b/libcxx/include/array
@@ -10,103 +10,7 @@
 #ifndef _LIBCPP_ARRAY
 #define _LIBCPP_ARRAY
 
-/*
-    array synopsis
-
-namespace std
-{
-template <class T, size_t N >
-struct array
-{
-    // types:
-    typedef T & reference;
-    typedef const T & const_reference;
-    typedef implementation defined iterator;
-    typedef implementation defined const_iterator;
-    typedef size_t size_type;
-    typedef ptrdiff_t difference_type;
-    typedef T value_type;
-    typedef T* pointer;
-    typedef const T* const_pointer;
-    typedef std::reverse_iterator<iterator> reverse_iterator;
-    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
-
-    // No explicit construct/copy/destroy for aggregate type
-    void fill(const T& u);                                      // constexpr in C++20
-    void swap(array& a) noexcept(is_nothrow_swappable_v<T>);    // constexpr in C++20
-
-    // iterators:
-    iterator begin() noexcept;                                  // constexpr in C++17
-    const_iterator begin() const noexcept;                      // constexpr in C++17
-    iterator end() noexcept;                                    // constexpr in C++17
-    const_iterator end() const noexcept;                        // constexpr in C++17
-
-    reverse_iterator rbegin() noexcept;                         // constexpr in C++17
-    const_reverse_iterator rbegin() const noexcept;             // constexpr in C++17
-    reverse_iterator rend() noexcept;                           // constexpr in C++17
-    const_reverse_iterator rend() const noexcept;               // constexpr in C++17
-
-    const_iterator cbegin() const noexcept;                     // constexpr in C++17
-    const_iterator cend() const noexcept;                       // constexpr in C++17
-    const_reverse_iterator crbegin() const noexcept;            // constexpr in C++17
-    const_reverse_iterator crend() const noexcept;              // constexpr in C++17
-
-    // capacity:
-    constexpr size_type size() const noexcept;
-    constexpr size_type max_size() const noexcept;
-    constexpr bool empty() const noexcept;
-
-    // element access:
-    reference operator[](size_type n);                          // constexpr in C++17
-    const_reference operator[](size_type n) const;              // constexpr in C++14
-    reference at(size_type n);                                  // constexpr in C++17
-    const_reference at(size_type n) const;                      // constexpr in C++14
-
-    reference front();                                          // constexpr in C++17
-    const_reference front() const;                              // constexpr in C++14
-    reference back();                                           // constexpr in C++17
-    const_reference back() const;                               // constexpr in C++14
-
-    T* data() noexcept;                                         // constexpr in C++17
-    const T* data() const noexcept;                             // constexpr in C++17
-};
-
-template <class T, class... U>
-  array(T, U...) -> array<T, 1 + sizeof...(U)>;                 // C++17
-
-template <class T, size_t N>
-  bool operator==(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
-template <class T, size_t N>
-  bool operator!=(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
-template <class T, size_t N>
-  bool operator<(const array<T,N>& x, const array<T,N>& y);     // constexpr in C++20
-template <class T, size_t N>
-  bool operator>(const array<T,N>& x, const array<T,N>& y);     // constexpr in C++20
-template <class T, size_t N>
-  bool operator<=(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
-template <class T, size_t N>
-  bool operator>=(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
-
-template <class T, size_t N >
-  void swap(array<T,N>& x, array<T,N>& y) noexcept(noexcept(x.swap(y))); // constexpr in C++20
-
-template <class T, size_t N>
-  constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);  // C++20
-template <class T, size_t N>
-  constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]); // C++20
-
-template <class T> struct tuple_size;
-template <size_t I, class T> struct tuple_element;
-template <class T, size_t N> struct tuple_size<array<T, N>>;
-template <size_t I, class T, size_t N> struct tuple_element<I, array<T, N>>;
-template <size_t I, class T, size_t N> T& get(array<T, N>&) noexcept;               // constexpr in C++14
-template <size_t I, class T, size_t N> const T& get(const array<T, N>&) noexcept;   // constexpr in C++14
-template <size_t I, class T, size_t N> T&& get(array<T, N>&&) noexcept;             // constexpr in C++14
-template <size_t I, class T, size_t N> const T&& get(const array<T, N>&&) noexcept; // constexpr in C++14
-
-}  // std
-
-*/
+// Synopsis available at http://wg21.link/array.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/atomic b/libcxx/include/atomic
--- a/libcxx/include/atomic
+++ b/libcxx/include/atomic
@@ -10,572 +10,7 @@
 #ifndef _LIBCPP_ATOMIC
 #define _LIBCPP_ATOMIC
 
-/*
-    atomic synopsis
-
-namespace std
-{
-
-// feature test macro [version.syn]
-
-#define __cpp_lib_atomic_is_always_lock_free
-#define __cpp_lib_atomic_flag_test
-#define __cpp_lib_atomic_lock_free_type_aliases
-#define __cpp_lib_atomic_wait
-
- // order and consistency
-
- enum memory_order: unspecified // enum class in C++20
- {
-    relaxed,
-    consume, // load-consume
-    acquire, // load-acquire
-    release, // store-release
-    acq_rel, // store-release load-acquire
-    seq_cst // store-release load-acquire
- };
-
- inline constexpr auto memory_order_relaxed = memory_order::relaxed;
- inline constexpr auto memory_order_consume = memory_order::consume;
- inline constexpr auto memory_order_acquire = memory_order::acquire;
- inline constexpr auto memory_order_release = memory_order::release;
- inline constexpr auto memory_order_acq_rel = memory_order::acq_rel;
- inline constexpr auto memory_order_seq_cst = memory_order::seq_cst;
-
-template <class T> T kill_dependency(T y) noexcept;
-
-// lock-free property
-
-#define ATOMIC_BOOL_LOCK_FREE unspecified
-#define ATOMIC_CHAR_LOCK_FREE unspecified
-#define ATOMIC_CHAR8_T_LOCK_FREE unspecified // C++20
-#define ATOMIC_CHAR16_T_LOCK_FREE unspecified
-#define ATOMIC_CHAR32_T_LOCK_FREE unspecified
-#define ATOMIC_WCHAR_T_LOCK_FREE unspecified
-#define ATOMIC_SHORT_LOCK_FREE unspecified
-#define ATOMIC_INT_LOCK_FREE unspecified
-#define ATOMIC_LONG_LOCK_FREE unspecified
-#define ATOMIC_LLONG_LOCK_FREE unspecified
-#define ATOMIC_POINTER_LOCK_FREE unspecified
-
-template <class T>
-struct atomic
-{
-    using value_type = T;
-
-    static constexpr bool is_always_lock_free;
-    bool is_lock_free() const volatile noexcept;
-    bool is_lock_free() const noexcept;
-
-    atomic() noexcept = default; // until C++20
-    constexpr atomic() noexcept(is_nothrow_default_constructible_v<T>); // since C++20
-    constexpr atomic(T desr) noexcept;
-    atomic(const atomic&) = delete;
-    atomic& operator=(const atomic&) = delete;
-    atomic& operator=(const atomic&) volatile = delete;
-
-    T load(memory_order m = memory_order_seq_cst) const volatile noexcept;
-    T load(memory_order m = memory_order_seq_cst) const noexcept;
-    operator T() const volatile noexcept;
-    operator T() const noexcept;
-    void store(T desr, memory_order m = memory_order_seq_cst) volatile noexcept;
-    void store(T desr, memory_order m = memory_order_seq_cst) noexcept;
-    T operator=(T) volatile noexcept;
-    T operator=(T) noexcept;
-
-    T exchange(T desr, memory_order m = memory_order_seq_cst) volatile noexcept;
-    T exchange(T desr, memory_order m = memory_order_seq_cst) noexcept;
-    bool compare_exchange_weak(T& expc, T desr,
-                               memory_order s, memory_order f) volatile noexcept;
-    bool compare_exchange_weak(T& expc, T desr, memory_order s, memory_order f) noexcept;
-    bool compare_exchange_strong(T& expc, T desr,
-                                 memory_order s, memory_order f) volatile noexcept;
-    bool compare_exchange_strong(T& expc, T desr,
-                                 memory_order s, memory_order f) noexcept;
-    bool compare_exchange_weak(T& expc, T desr,
-                               memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool compare_exchange_weak(T& expc, T desr,
-                               memory_order m = memory_order_seq_cst) noexcept;
-    bool compare_exchange_strong(T& expc, T desr,
-                                memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool compare_exchange_strong(T& expc, T desr,
-                                 memory_order m = memory_order_seq_cst) noexcept;
-
-    void wait(T, memory_order = memory_order::seq_cst) const volatile noexcept;
-    void wait(T, memory_order = memory_order::seq_cst) const noexcept;
-    void notify_one() volatile noexcept;
-    void notify_one() noexcept;
-    void notify_all() volatile noexcept;
-    void notify_all() noexcept;
-};
-
-template <>
-struct atomic<integral>
-{
-    using value_type = integral;
-    using difference_type = value_type;
-
-    static constexpr bool is_always_lock_free;
-    bool is_lock_free() const volatile noexcept;
-    bool is_lock_free() const noexcept;
-
-    atomic() noexcept = default;
-    constexpr atomic(integral desr) noexcept;
-    atomic(const atomic&) = delete;
-    atomic& operator=(const atomic&) = delete;
-    atomic& operator=(const atomic&) volatile = delete;
-
-    integral load(memory_order m = memory_order_seq_cst) const volatile noexcept;
-    integral load(memory_order m = memory_order_seq_cst) const noexcept;
-    operator integral() const volatile noexcept;
-    operator integral() const noexcept;
-    void store(integral desr, memory_order m = memory_order_seq_cst) volatile noexcept;
-    void store(integral desr, memory_order m = memory_order_seq_cst) noexcept;
-    integral operator=(integral desr) volatile noexcept;
-    integral operator=(integral desr) noexcept;
-
-    integral exchange(integral desr,
-                      memory_order m = memory_order_seq_cst) volatile noexcept;
-    integral exchange(integral desr, memory_order m = memory_order_seq_cst) noexcept;
-    bool compare_exchange_weak(integral& expc, integral desr,
-                               memory_order s, memory_order f) volatile noexcept;
-    bool compare_exchange_weak(integral& expc, integral desr,
-                               memory_order s, memory_order f) noexcept;
-    bool compare_exchange_strong(integral& expc, integral desr,
-                                 memory_order s, memory_order f) volatile noexcept;
-    bool compare_exchange_strong(integral& expc, integral desr,
-                                 memory_order s, memory_order f) noexcept;
-    bool compare_exchange_weak(integral& expc, integral desr,
-                               memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool compare_exchange_weak(integral& expc, integral desr,
-                               memory_order m = memory_order_seq_cst) noexcept;
-    bool compare_exchange_strong(integral& expc, integral desr,
-                                memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool compare_exchange_strong(integral& expc, integral desr,
-                                 memory_order m = memory_order_seq_cst) noexcept;
-
-    integral fetch_add(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    integral fetch_add(integral op, memory_order m = memory_order_seq_cst) noexcept;
-    integral fetch_sub(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    integral fetch_sub(integral op, memory_order m = memory_order_seq_cst) noexcept;
-    integral fetch_and(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    integral fetch_and(integral op, memory_order m = memory_order_seq_cst) noexcept;
-    integral fetch_or(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    integral fetch_or(integral op, memory_order m = memory_order_seq_cst) noexcept;
-    integral fetch_xor(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    integral fetch_xor(integral op, memory_order m = memory_order_seq_cst) noexcept;
-
-    integral operator++(int) volatile noexcept;
-    integral operator++(int) noexcept;
-    integral operator--(int) volatile noexcept;
-    integral operator--(int) noexcept;
-    integral operator++() volatile noexcept;
-    integral operator++() noexcept;
-    integral operator--() volatile noexcept;
-    integral operator--() noexcept;
-    integral operator+=(integral op) volatile noexcept;
-    integral operator+=(integral op) noexcept;
-    integral operator-=(integral op) volatile noexcept;
-    integral operator-=(integral op) noexcept;
-    integral operator&=(integral op) volatile noexcept;
-    integral operator&=(integral op) noexcept;
-    integral operator|=(integral op) volatile noexcept;
-    integral operator|=(integral op) noexcept;
-    integral operator^=(integral op) volatile noexcept;
-    integral operator^=(integral op) noexcept;
-
-    void wait(integral, memory_order = memory_order::seq_cst) const volatile noexcept;
-    void wait(integral, memory_order = memory_order::seq_cst) const noexcept;
-    void notify_one() volatile noexcept;
-    void notify_one() noexcept;
-    void notify_all() volatile noexcept;
-    void notify_all() noexcept;
-};
-
-template <class T>
-struct atomic<T*>
-{
-    using value_type = T*;
-    using difference_type = ptrdiff_t;
-
-    static constexpr bool is_always_lock_free;
-    bool is_lock_free() const volatile noexcept;
-    bool is_lock_free() const noexcept;
-
-    atomic() noexcept = default; // until C++20
-    constexpr atomic() noexcept; // since C++20
-    constexpr atomic(T* desr) noexcept;
-    atomic(const atomic&) = delete;
-    atomic& operator=(const atomic&) = delete;
-    atomic& operator=(const atomic&) volatile = delete;
-
-    T* load(memory_order m = memory_order_seq_cst) const volatile noexcept;
-    T* load(memory_order m = memory_order_seq_cst) const noexcept;
-    operator T*() const volatile noexcept;
-    operator T*() const noexcept;
-    void store(T* desr, memory_order m = memory_order_seq_cst) volatile noexcept;
-    void store(T* desr, memory_order m = memory_order_seq_cst) noexcept;
-    T* operator=(T*) volatile noexcept;
-    T* operator=(T*) noexcept;
-
-    T* exchange(T* desr, memory_order m = memory_order_seq_cst) volatile noexcept;
-    T* exchange(T* desr, memory_order m = memory_order_seq_cst) noexcept;
-    bool compare_exchange_weak(T*& expc, T* desr,
-                               memory_order s, memory_order f) volatile noexcept;
-    bool compare_exchange_weak(T*& expc, T* desr,
-                               memory_order s, memory_order f) noexcept;
-    bool compare_exchange_strong(T*& expc, T* desr,
-                                 memory_order s, memory_order f) volatile noexcept;
-    bool compare_exchange_strong(T*& expc, T* desr,
-                                 memory_order s, memory_order f) noexcept;
-    bool compare_exchange_weak(T*& expc, T* desr,
-                               memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool compare_exchange_weak(T*& expc, T* desr,
-                               memory_order m = memory_order_seq_cst) noexcept;
-    bool compare_exchange_strong(T*& expc, T* desr,
-                                memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool compare_exchange_strong(T*& expc, T* desr,
-                                 memory_order m = memory_order_seq_cst) noexcept;
-    T* fetch_add(ptrdiff_t op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    T* fetch_add(ptrdiff_t op, memory_order m = memory_order_seq_cst) noexcept;
-    T* fetch_sub(ptrdiff_t op, memory_order m = memory_order_seq_cst) volatile noexcept;
-    T* fetch_sub(ptrdiff_t op, memory_order m = memory_order_seq_cst) noexcept;
-
-    T* operator++(int) volatile noexcept;
-    T* operator++(int) noexcept;
-    T* operator--(int) volatile noexcept;
-    T* operator--(int) noexcept;
-    T* operator++() volatile noexcept;
-    T* operator++() noexcept;
-    T* operator--() volatile noexcept;
-    T* operator--() noexcept;
-    T* operator+=(ptrdiff_t op) volatile noexcept;
-    T* operator+=(ptrdiff_t op) noexcept;
-    T* operator-=(ptrdiff_t op) volatile noexcept;
-    T* operator-=(ptrdiff_t op) noexcept;
-
-    void wait(T*, memory_order = memory_order::seq_cst) const volatile noexcept;
-    void wait(T*, memory_order = memory_order::seq_cst) const noexcept;
-    void notify_one() volatile noexcept;
-    void notify_one() noexcept;
-    void notify_all() volatile noexcept;
-    void notify_all() noexcept;
-};
-
-
-template <class T>
-  bool atomic_is_lock_free(const volatile atomic<T>* obj) noexcept;
-
-template <class T>
-  bool atomic_is_lock_free(const atomic<T>* obj) noexcept;
-
-template <class T>
-  void atomic_store(volatile atomic<T>* obj, T desr) noexcept;
-
-template <class T>
-  void atomic_store(atomic<T>* obj, T desr) noexcept;
-
-template <class T>
-  void atomic_store_explicit(volatile atomic<T>* obj, T desr, memory_order m) noexcept;
-
-template <class T>
-  void atomic_store_explicit(atomic<T>* obj, T desr, memory_order m) noexcept;
-
-template <class T>
-  T atomic_load(const volatile atomic<T>* obj) noexcept;
-
-template <class T>
-  T atomic_load(const atomic<T>* obj) noexcept;
-
-template <class T>
-  T atomic_load_explicit(const volatile atomic<T>* obj, memory_order m) noexcept;
-
-template <class T>
-  T atomic_load_explicit(const atomic<T>* obj, memory_order m) noexcept;
-
-template <class T>
-  T atomic_exchange(volatile atomic<T>* obj, T desr) noexcept;
-
-template <class T>
-  T atomic_exchange(atomic<T>* obj, T desr) noexcept;
-
-template <class T>
-  T atomic_exchange_explicit(volatile atomic<T>* obj, T desr, memory_order m) noexcept;
-
-template <class T>
-  T atomic_exchange_explicit(atomic<T>* obj, T desr, memory_order m) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_weak(volatile atomic<T>* obj, T* expc, T desr) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_weak(atomic<T>* obj, T* expc, T desr) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_strong(volatile atomic<T>* obj, T* expc, T desr) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_strong(atomic<T>* obj, T* expc, T desr) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_weak_explicit(volatile atomic<T>* obj, T* expc,
-                                             T desr,
-                                             memory_order s, memory_order f) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_weak_explicit(atomic<T>* obj, T* expc, T desr,
-                                             memory_order s, memory_order f) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_strong_explicit(volatile atomic<T>* obj,
-                                               T* expc, T desr,
-                                               memory_order s, memory_order f) noexcept;
-
-template <class T>
-  bool atomic_compare_exchange_strong_explicit(atomic<T>* obj, T* expc,
-                                               T desr,
-                                               memory_order s, memory_order f) noexcept;
-
-template <class T>
-  void atomic_wait(const volatile atomic<T>* obj, T old) noexcept;
-
-template <class T>
-  void atomic_wait(const atomic<T>* obj, T old) noexcept;
-
-template <class T>
-  void atomic_wait_explicit(const volatile atomic<T>* obj, T old, memory_order m) noexcept;
-
-template <class T>
-  void atomic_wait_explicit(const atomic<T>* obj, T old, memory_order m) noexcept;
-
-template <class T>
-  void atomic_one(volatile atomic<T>* obj) noexcept;
-
-template <class T>
-  void atomic_one(atomic<T>* obj) noexcept;
-
-template <class T>
-  void atomic_all(volatile atomic<T>* obj) noexcept;
-
-template <class T>
-  void atomic_all(atomic<T>* obj) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_add(volatile atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_add(atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_add_explicit(volatile atomic<Integral>* obj, Integral op,
-                              memory_order m) noexcept;
-template <class Integral>
-  Integral atomic_fetch_add_explicit(atomic<Integral>* obj, Integral op,
-                              memory_order m) noexcept;
-template <class Integral>
-  Integral atomic_fetch_sub(volatile atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_sub(atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_sub_explicit(volatile atomic<Integral>* obj, Integral op,
-                                     memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_sub_explicit(atomic<Integral>* obj, Integral op,
-                                     memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_and(volatile atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_and(atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_and_explicit(volatile atomic<Integral>* obj, Integral op,
-                                     memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_and_explicit(atomic<Integral>* obj, Integral op,
-                                     memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_or(volatile atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_or(atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_or_explicit(volatile atomic<Integral>* obj, Integral op,
-                             memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_or_explicit(atomic<Integral>* obj, Integral op,
-                             memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_xor(volatile atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_xor(atomic<Integral>* obj, Integral op) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_xor_explicit(volatile atomic<Integral>* obj, Integral op,
-                                     memory_order m) noexcept;
-
-template <class Integral>
-  Integral atomic_fetch_xor_explicit(atomic<Integral>* obj, Integral op,
-                                     memory_order m) noexcept;
-
-template <class T>
-  T* atomic_fetch_add(volatile atomic<T*>* obj, ptrdiff_t op) noexcept;
-
-template <class T>
-  T* atomic_fetch_add(atomic<T*>* obj, ptrdiff_t op) noexcept;
-
-template <class T>
-  T* atomic_fetch_add_explicit(volatile atomic<T*>* obj, ptrdiff_t op,
-                               memory_order m) noexcept;
-
-template <class T>
-  T* atomic_fetch_add_explicit(atomic<T*>* obj, ptrdiff_t op, memory_order m) noexcept;
-
-template <class T>
-  T* atomic_fetch_sub(volatile atomic<T*>* obj, ptrdiff_t op) noexcept;
-
-template <class T>
-  T* atomic_fetch_sub(atomic<T*>* obj, ptrdiff_t op) noexcept;
-
-template <class T>
-  T* atomic_fetch_sub_explicit(volatile atomic<T*>* obj, ptrdiff_t op,
-                               memory_order m) noexcept;
-
-template <class T>
-  T* atomic_fetch_sub_explicit(atomic<T*>* obj, ptrdiff_t op, memory_order m) noexcept;
-
-// Atomics for standard typedef types
-
-typedef atomic<bool>               atomic_bool;
-typedef atomic<char>               atomic_char;
-typedef atomic<signed char>        atomic_schar;
-typedef atomic<unsigned char>      atomic_uchar;
-typedef atomic<short>              atomic_short;
-typedef atomic<unsigned short>     atomic_ushort;
-typedef atomic<int>                atomic_int;
-typedef atomic<unsigned int>       atomic_uint;
-typedef atomic<long>               atomic_long;
-typedef atomic<unsigned long>      atomic_ulong;
-typedef atomic<long long>          atomic_llong;
-typedef atomic<unsigned long long> atomic_ullong;
-typedef atomic<char8_t>            atomic_char8_t; // C++20
-typedef atomic<char16_t>           atomic_char16_t;
-typedef atomic<char32_t>           atomic_char32_t;
-typedef atomic<wchar_t>            atomic_wchar_t;
-
-typedef atomic<int_least8_t>   atomic_int_least8_t;
-typedef atomic<uint_least8_t>  atomic_uint_least8_t;
-typedef atomic<int_least16_t>  atomic_int_least16_t;
-typedef atomic<uint_least16_t> atomic_uint_least16_t;
-typedef atomic<int_least32_t>  atomic_int_least32_t;
-typedef atomic<uint_least32_t> atomic_uint_least32_t;
-typedef atomic<int_least64_t>  atomic_int_least64_t;
-typedef atomic<uint_least64_t> atomic_uint_least64_t;
-
-typedef atomic<int_fast8_t>   atomic_int_fast8_t;
-typedef atomic<uint_fast8_t>  atomic_uint_fast8_t;
-typedef atomic<int_fast16_t>  atomic_int_fast16_t;
-typedef atomic<uint_fast16_t> atomic_uint_fast16_t;
-typedef atomic<int_fast32_t>  atomic_int_fast32_t;
-typedef atomic<uint_fast32_t> atomic_uint_fast32_t;
-typedef atomic<int_fast64_t>  atomic_int_fast64_t;
-typedef atomic<uint_fast64_t> atomic_uint_fast64_t;
-
-typedef atomic<int8_t>   atomic_int8_t;
-typedef atomic<uint8_t>  atomic_uint8_t;
-typedef atomic<int16_t>  atomic_int16_t;
-typedef atomic<uint16_t> atomic_uint16_t;
-typedef atomic<int32_t>  atomic_int32_t;
-typedef atomic<uint32_t> atomic_uint32_t;
-typedef atomic<int64_t>  atomic_int64_t;
-typedef atomic<uint64_t> atomic_uint64_t;
-
-typedef atomic<intptr_t>  atomic_intptr_t;
-typedef atomic<uintptr_t> atomic_uintptr_t;
-typedef atomic<size_t>    atomic_size_t;
-typedef atomic<ptrdiff_t> atomic_ptrdiff_t;
-typedef atomic<intmax_t>  atomic_intmax_t;
-typedef atomic<uintmax_t> atomic_uintmax_t;
-
-// flag type and operations
-
-typedef struct atomic_flag
-{
-    atomic_flag() noexcept = default; // until C++20
-    constexpr atomic_flag() noexcept; // since C++20
-    atomic_flag(const atomic_flag&) = delete;
-    atomic_flag& operator=(const atomic_flag&) = delete;
-    atomic_flag& operator=(const atomic_flag&) volatile = delete;
-
-    bool test(memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool test(memory_order m = memory_order_seq_cst) noexcept;
-    bool test_and_set(memory_order m = memory_order_seq_cst) volatile noexcept;
-    bool test_and_set(memory_order m = memory_order_seq_cst) noexcept;
-    void clear(memory_order m = memory_order_seq_cst) volatile noexcept;
-    void clear(memory_order m = memory_order_seq_cst) noexcept;
-
-    void wait(bool, memory_order = memory_order::seq_cst) const volatile noexcept;
-    void wait(bool, memory_order = memory_order::seq_cst) const noexcept;
-    void notify_one() volatile noexcept;
-    void notify_one() noexcept;
-    void notify_all() volatile noexcept;
-    void notify_all() noexcept;
-} atomic_flag;
-
-bool atomic_flag_test(volatile atomic_flag* obj) noexcept;
-bool atomic_flag_test(atomic_flag* obj) noexcept;
-bool atomic_flag_test_explicit(volatile atomic_flag* obj,
-                               memory_order m) noexcept;
-bool atomic_flag_test_explicit(atomic_flag* obj, memory_order m) noexcept;
-bool atomic_flag_test_and_set(volatile atomic_flag* obj) noexcept;
-bool atomic_flag_test_and_set(atomic_flag* obj) noexcept;
-bool atomic_flag_test_and_set_explicit(volatile atomic_flag* obj,
-                                       memory_order m) noexcept;
-bool atomic_flag_test_and_set_explicit(atomic_flag* obj, memory_order m) noexcept;
-void atomic_flag_clear(volatile atomic_flag* obj) noexcept;
-void atomic_flag_clear(atomic_flag* obj) noexcept;
-void atomic_flag_clear_explicit(volatile atomic_flag* obj, memory_order m) noexcept;
-void atomic_flag_clear_explicit(atomic_flag* obj, memory_order m) noexcept;
-
-void atomic_wait(const volatile atomic_flag* obj, T old) noexcept;
-void atomic_wait(const atomic_flag* obj, T old) noexcept;
-void atomic_wait_explicit(const volatile atomic_flag* obj, T old, memory_order m) noexcept;
-void atomic_wait_explicit(const atomic_flag* obj, T old, memory_order m) noexcept;
-void atomic_one(volatile atomic_flag* obj) noexcept;
-void atomic_one(atomic_flag* obj) noexcept;
-void atomic_all(volatile atomic_flag* obj) noexcept;
-void atomic_all(atomic_flag* obj) noexcept;
-
-// fences
-
-void atomic_thread_fence(memory_order m) noexcept;
-void atomic_signal_fence(memory_order m) noexcept;
-
-// deprecated
-
-template <class T>
-  void atomic_init(volatile atomic<T>* obj, typename atomic<T>::value_type desr) noexcept;
-
-template <class T>
-  void atomic_init(atomic<T>* obj, typename atomic<T>::value_type desr) noexcept;
-
-#define ATOMIC_VAR_INIT(value) see below
-
-#define ATOMIC_FLAG_INIT see below
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/atomics.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/barrier b/libcxx/include/barrier
--- a/libcxx/include/barrier
+++ b/libcxx/include/barrier
@@ -10,40 +10,7 @@
 #ifndef _LIBCPP_BARRIER
 #define _LIBCPP_BARRIER
 
-/*
-    barrier synopsis
-
-namespace std
-{
-
-  template<class CompletionFunction = see below>
-  class barrier
-  {
-  public:
-    using arrival_token = see below;
-
-    static constexpr ptrdiff_t max() noexcept;
-
-    constexpr explicit barrier(ptrdiff_t phase_count,
-                               CompletionFunction f = CompletionFunction());
-    ~barrier();
-
-    barrier(const barrier&) = delete;
-    barrier& operator=(const barrier&) = delete;
-
-    [[nodiscard]] arrival_token arrive(ptrdiff_t update = 1);
-    void wait(arrival_token&& arrival) const;
-
-    void arrive_and_wait();
-    void arrive_and_drop();
-
-  private:
-    CompletionFunction completion; // exposition only
-  };
-
-}
-
-*/
+// Synopsis avaiable at http://wg21.link/barrier.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/bit b/libcxx/include/bit
--- a/libcxx/include/bit
+++ b/libcxx/include/bit
@@ -10,49 +10,7 @@
 #ifndef _LIBCPP_BIT
 #define _LIBCPP_BIT
 
-/*
-    bit synopsis
-
-namespace std {
-
-  // [bit.pow.two], integral powers of 2
-  template <class T>
-    constexpr bool has_single_bit(T x) noexcept; // C++20
-  template <class T>
-    constexpr T bit_ceil(T x);                   // C++20
-  template <class T>
-    constexpr T bit_floor(T x) noexcept;         // C++20
-  template <class T>
-    constexpr T bit_width(T x) noexcept;         // C++20
-
-  // [bit.rotate], rotating
-  template<class T>
-    constexpr T rotl(T x, unsigned int s) noexcept; // C++20
-  template<class T>
-    constexpr T rotr(T x, unsigned int s) noexcept; // C++20
-
-  // [bit.count], counting
-  template<class T>
-    constexpr int countl_zero(T x) noexcept;  // C++20
-  template<class T>
-    constexpr int countl_one(T x) noexcept;   // C++20
-  template<class T>
-    constexpr int countr_zero(T x) noexcept;  // C++20
-  template<class T>
-    constexpr int countr_one(T x) noexcept;   // C++20
-  template<class T>
-    constexpr int popcount(T x) noexcept;     // C++20
-
-  // [bit.endian], endian
-  enum class endian {
-    little = see below,        // C++20
-    big = see below,           // C++20
-    native = see below         // C++20
-};
-
-} // namespace std
-
-*/
+// Synopsis avaiable at http://wg21.link/bit.syn.
 
 #include <__config>
 #include <__bits> // __libcpp_clz
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -10,107 +10,7 @@
 #ifndef _LIBCPP_BITSET
 #define _LIBCPP_BITSET
 
-/*
-    bitset synopsis
-
-namespace std
-{
-
-namespace std {
-
-template <size_t N>
-class bitset
-{
-public:
-    // bit reference:
-    class reference
-    {
-        friend class bitset;
-        reference() noexcept;
-    public:
-        ~reference() noexcept;
-        reference& operator=(bool x) noexcept;           // for b[i] = x;
-        reference& operator=(const reference&) noexcept; // for b[i] = b[j];
-        bool operator~() const noexcept;                 // flips the bit
-        operator bool() const noexcept;                  // for x = b[i];
-        reference& flip() noexcept;                      // for b[i].flip();
-    };
-
-    // 23.3.5.1 constructors:
-    constexpr bitset() noexcept;
-    constexpr bitset(unsigned long long val) noexcept;
-    template <class charT>
-        explicit bitset(const charT* str,
-                        typename basic_string<charT>::size_type n = basic_string<charT>::npos,
-                        charT zero = charT('0'), charT one = charT('1'));
-    template<class charT, class traits, class Allocator>
-        explicit bitset(const basic_string<charT,traits,Allocator>& str,
-                        typename basic_string<charT,traits,Allocator>::size_type pos = 0,
-                        typename basic_string<charT,traits,Allocator>::size_type n =
-                                 basic_string<charT,traits,Allocator>::npos,
-                        charT zero = charT('0'), charT one = charT('1'));
-
-    // 23.3.5.2 bitset operations:
-    bitset& operator&=(const bitset& rhs) noexcept;
-    bitset& operator|=(const bitset& rhs) noexcept;
-    bitset& operator^=(const bitset& rhs) noexcept;
-    bitset& operator<<=(size_t pos) noexcept;
-    bitset& operator>>=(size_t pos) noexcept;
-    bitset& set() noexcept;
-    bitset& set(size_t pos, bool val = true);
-    bitset& reset() noexcept;
-    bitset& reset(size_t pos);
-    bitset operator~() const noexcept;
-    bitset& flip() noexcept;
-    bitset& flip(size_t pos);
-
-    // element access:
-    constexpr bool operator[](size_t pos) const; // for b[i];
-    reference operator[](size_t pos);            // for b[i];
-    unsigned long to_ulong() const;
-    unsigned long long to_ullong() const;
-    template <class charT, class traits, class Allocator>
-        basic_string<charT, traits, Allocator> to_string(charT zero = charT('0'), charT one = charT('1')) const;
-    template <class charT, class traits>
-        basic_string<charT, traits, allocator<charT> > to_string(charT zero = charT('0'), charT one = charT('1')) const;
-    template <class charT>
-        basic_string<charT, char_traits<charT>, allocator<charT> > to_string(charT zero = charT('0'), charT one = charT('1')) const;
-    basic_string<char, char_traits<char>, allocator<char> > to_string(char zero = '0', char one = '1') const;
-    size_t count() const noexcept;
-    constexpr size_t size() const noexcept;
-    bool operator==(const bitset& rhs) const noexcept;
-    bool operator!=(const bitset& rhs) const noexcept;
-    bool test(size_t pos) const;
-    bool all() const noexcept;
-    bool any() const noexcept;
-    bool none() const noexcept;
-    bitset operator<<(size_t pos) const noexcept;
-    bitset operator>>(size_t pos) const noexcept;
-};
-
-// 23.3.5.3 bitset operators:
-template <size_t N>
-bitset<N> operator&(const bitset<N>&, const bitset<N>&) noexcept;
-
-template <size_t N>
-bitset<N> operator|(const bitset<N>&, const bitset<N>&) noexcept;
-
-template <size_t N>
-bitset<N> operator^(const bitset<N>&, const bitset<N>&) noexcept;
-
-template <class charT, class traits, size_t N>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is, bitset<N>& x);
-
-template <class charT, class traits, size_t N>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os, const bitset<N>& x);
-
-template <size_t N> struct hash<std::bitset<N>>;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/bitset.syn.
 
 #include <__config>
 #include <__bit_reference>
diff --git a/libcxx/include/cassert b/libcxx/include/cassert
--- a/libcxx/include/cassert
+++ b/libcxx/include/cassert
@@ -7,14 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-/*
-    cassert synopsis
-
-Macros:
-
-    assert
-
-*/
+// Synopsis avaiable at http://wg21.link/cassert.syn.
 
 #include <__config>
 #include <assert.h>
diff --git a/libcxx/include/cctype b/libcxx/include/cctype
--- a/libcxx/include/cctype
+++ b/libcxx/include/cctype
@@ -10,29 +10,7 @@
 #ifndef _LIBCPP_CCTYPE
 #define _LIBCPP_CCTYPE
 
-/*
-    cctype synopsis
-
-namespace std
-{
-
-int isalnum(int c);
-int isalpha(int c);
-int isblank(int c);  // C99
-int iscntrl(int c);
-int isdigit(int c);
-int isgraph(int c);
-int islower(int c);
-int isprint(int c);
-int ispunct(int c);
-int isspace(int c);
-int isupper(int c);
-int isxdigit(int c);
-int tolower(int c);
-int toupper(int c);
-
-}  // std
-*/
+// Synopsis avaiable at http://wg21.link/cctype.syn.
 
 #include <__config>
 #include <ctype.h>
diff --git a/libcxx/include/cerrno b/libcxx/include/cerrno
--- a/libcxx/include/cerrno
+++ b/libcxx/include/cerrno
@@ -10,17 +10,7 @@
 #ifndef _LIBCPP_CERRNO
 #define _LIBCPP_CERRNO
 
-/*
-    cerrno synopsis
-
-Macros:
-
-    EDOM
-    EILSEQ  // C99
-    ERANGE
-    errno
-
-*/
+// Synopsis avaiable at http://wg21.link/cerrno.syn.
 
 #include <__config>
 #include <errno.h>
diff --git a/libcxx/include/cfenv b/libcxx/include/cfenv
--- a/libcxx/include/cfenv
+++ b/libcxx/include/cfenv
@@ -10,47 +10,7 @@
 #ifndef _LIBCPP_CFENV
 #define _LIBCPP_CFENV
 
-/*
-    cfenv synopsis
-
-This entire header is C99 / C++0X
-
-Macros:
-
-    FE_DIVBYZERO
-    FE_INEXACT
-    FE_INVALID
-    FE_OVERFLOW
-    FE_UNDERFLOW
-    FE_ALL_EXCEPT
-    FE_DOWNWARD
-    FE_TONEAREST
-    FE_TOWARDZERO
-    FE_UPWARD
-    FE_DFL_ENV
-
-namespace std
-{
-
-Types:
-
-    fenv_t
-    fexcept_t
-
-int feclearexcept(int excepts);
-int fegetexceptflag(fexcept_t* flagp, int excepts);
-int feraiseexcept(int excepts);
-int fesetexceptflag(const fexcept_t* flagp, int excepts);
-int fetestexcept(int excepts);
-int fegetround();
-int fesetround(int round);
-int fegetenv(fenv_t* envp);
-int feholdexcept(fenv_t* envp);
-int fesetenv(const fenv_t* envp);
-int feupdateenv(const fenv_t* envp);
-
-}  // std
-*/
+// Synopsis avaiable at http://wg21.link/cfenv.syn.
 
 #include <__config>
 #include <fenv.h>
diff --git a/libcxx/include/cfloat b/libcxx/include/cfloat
--- a/libcxx/include/cfloat
+++ b/libcxx/include/cfloat
@@ -10,64 +10,7 @@
 #ifndef _LIBCPP_CFLOAT
 #define _LIBCPP_CFLOAT
 
-/*
-    cfloat synopsis
-
-Macros:
-
-    FLT_ROUNDS
-    FLT_EVAL_METHOD     // C99
-    FLT_RADIX
-
-    FLT_HAS_SUBNORM     // C11
-    DBL_HAS_SUBNORM     // C11
-    LDBL_HAS_SUBNORM    // C11
-
-    FLT_MANT_DIG
-    DBL_MANT_DIG
-    LDBL_MANT_DIG
-
-    DECIMAL_DIG         // C99
-    FLT_DECIMAL_DIG     // C11
-    DBL_DECIMAL_DIG     // C11
-    LDBL_DECIMAL_DIG    // C11
-
-    FLT_DIG
-    DBL_DIG
-    LDBL_DIG
-
-    FLT_MIN_EXP
-    DBL_MIN_EXP
-    LDBL_MIN_EXP
-
-    FLT_MIN_10_EXP
-    DBL_MIN_10_EXP
-    LDBL_MIN_10_EXP
-
-    FLT_MAX_EXP
-    DBL_MAX_EXP
-    LDBL_MAX_EXP
-
-    FLT_MAX_10_EXP
-    DBL_MAX_10_EXP
-    LDBL_MAX_10_EXP
-
-    FLT_MAX
-    DBL_MAX
-    LDBL_MAX
-
-    FLT_EPSILON
-    DBL_EPSILON
-    LDBL_EPSILON
-
-    FLT_MIN
-    DBL_MIN
-    LDBL_MIN
-
-    FLT_TRUE_MIN        // C11
-    DBL_TRUE_MIN        // C11
-    LDBL_TRUE_MIN       // C11
-*/
+// Synopsis avaiable at http://wg21.link/cfloat.syn.
 
 #include <__config>
 #include <float.h>
diff --git a/libcxx/include/charconv b/libcxx/include/charconv
--- a/libcxx/include/charconv
+++ b/libcxx/include/charconv
@@ -10,68 +10,7 @@
 #ifndef _LIBCPP_CHARCONV
 #define _LIBCPP_CHARCONV
 
-/*
-    charconv synopsis
-
-namespace std {
-
-  // floating-point format for primitive numerical conversion
-  enum class chars_format {
-    scientific = unspecified,
-    fixed = unspecified,
-    hex = unspecified,
-    general = fixed | scientific
-  };
-
-  // 23.20.2, primitive numerical output conversion
-  struct to_chars_result {
-    char* ptr;
-    errc ec;
-  };
-
-  to_chars_result to_chars(char* first, char* last, see below value,
-                           int base = 10);
-
-  to_chars_result to_chars(char* first, char* last, float value);
-  to_chars_result to_chars(char* first, char* last, double value);
-  to_chars_result to_chars(char* first, char* last, long double value);
-
-  to_chars_result to_chars(char* first, char* last, float value,
-                           chars_format fmt);
-  to_chars_result to_chars(char* first, char* last, double value,
-                           chars_format fmt);
-  to_chars_result to_chars(char* first, char* last, long double value,
-                           chars_format fmt);
-
-  to_chars_result to_chars(char* first, char* last, float value,
-                           chars_format fmt, int precision);
-  to_chars_result to_chars(char* first, char* last, double value,
-                           chars_format fmt, int precision);
-  to_chars_result to_chars(char* first, char* last, long double value,
-                           chars_format fmt, int precision);
-
-  // 23.20.3, primitive numerical input conversion
-  struct from_chars_result {
-    const char* ptr;
-    errc ec;
-  };
-
-  from_chars_result from_chars(const char* first, const char* last,
-                               see below& value, int base = 10);
-
-  from_chars_result from_chars(const char* first, const char* last,
-                               float& value,
-                               chars_format fmt = chars_format::general);
-  from_chars_result from_chars(const char* first, const char* last,
-                               double& value,
-                               chars_format fmt = chars_format::general);
-  from_chars_result from_chars(const char* first, const char* last,
-                               long double& value,
-                               chars_format fmt = chars_format::general);
-
-} // namespace std
-
-*/
+// Synopsis avaiable at http://wg21.link/charconv.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -10,818 +10,7 @@
 #ifndef _LIBCPP_CHRONO
 #define _LIBCPP_CHRONO
 
-/*
-    chrono synopsis
-
-namespace std
-{
-namespace chrono
-{
-
-template <class ToDuration, class Rep, class Period>
-constexpr
-ToDuration
-duration_cast(const duration<Rep, Period>& fd);
-
-template <class Rep> struct treat_as_floating_point : is_floating_point<Rep> {};
-
-template <class Rep> inline constexpr bool treat_as_floating_point_v
-    = treat_as_floating_point<Rep>::value;                       // C++17
-
-template <class Rep>
-struct duration_values
-{
-public:
-    static constexpr Rep zero(); // noexcept in C++20
-    static constexpr Rep max();  // noexcept in C++20
-    static constexpr Rep min();  // noexcept in C++20
-};
-
-// duration
-
-template <class Rep, class Period = ratio<1>>
-class duration
-{
-    static_assert(!__is_duration<Rep>::value, "A duration representation can not be a duration");
-    static_assert(__is_ratio<Period>::value, "Second template parameter of duration must be a std::ratio");
-    static_assert(Period::num > 0, "duration period must be positive");
-public:
-    typedef Rep rep;
-    typedef typename _Period::type period;
-
-    constexpr duration() = default;
-    template <class Rep2>
-        constexpr explicit duration(const Rep2& r,
-            typename enable_if
-            <
-               is_convertible<Rep2, rep>::value &&
-               (treat_as_floating_point<rep>::value ||
-               !treat_as_floating_point<rep>::value && !treat_as_floating_point<Rep2>::value)
-            >::type* = 0);
-
-    // conversions
-    template <class Rep2, class Period2>
-        constexpr duration(const duration<Rep2, Period2>& d,
-            typename enable_if
-            <
-                treat_as_floating_point<rep>::value ||
-                ratio_divide<Period2, period>::type::den == 1
-            >::type* = 0);
-
-    // observer
-
-    constexpr rep count() const;
-
-    // arithmetic
-
-    constexpr common_type<duration>::type  operator+() const;
-    constexpr common_type<duration>::type  operator-() const;
-    constexpr duration& operator++();    // constexpr in C++17
-    constexpr duration  operator++(int); // constexpr in C++17
-    constexpr duration& operator--();    // constexpr in C++17
-    constexpr duration  operator--(int); // constexpr in C++17
-
-    constexpr duration& operator+=(const duration& d);  // constexpr in C++17
-    constexpr duration& operator-=(const duration& d);  // constexpr in C++17
-
-    duration& operator*=(const rep& rhs);       // constexpr in C++17
-    duration& operator/=(const rep& rhs);       // constexpr in C++17
-    duration& operator%=(const rep& rhs);       // constexpr in C++17
-    duration& operator%=(const duration& rhs);  // constexpr in C++17
-
-    // special values
-
-    static constexpr duration zero(); // noexcept in C++20
-    static constexpr duration min();  // noexcept in C++20
-    static constexpr duration max();  // noexcept in C++20
-};
-
-typedef duration<long long,         nano> nanoseconds;
-typedef duration<long long,        micro> microseconds;
-typedef duration<long long,        milli> milliseconds;
-typedef duration<long long              > seconds;
-typedef duration<     long, ratio<  60> > minutes;
-typedef duration<     long, ratio<3600> > hours;
-
-template <class Clock, class Duration = typename Clock::duration>
-class time_point
-{
-public:
-    typedef Clock                     clock;
-    typedef Duration                  duration;
-    typedef typename duration::rep    rep;
-    typedef typename duration::period period;
-private:
-    duration d_;  // exposition only
-
-public:
-    time_point();  // has value "epoch" // constexpr in C++14
-    explicit time_point(const duration& d);  // same as time_point() + d // constexpr in C++14
-
-    // conversions
-    template <class Duration2>
-       time_point(const time_point<clock, Duration2>& t); // constexpr in C++14
-
-    // observer
-
-    duration time_since_epoch() const; // constexpr in C++14
-
-    // arithmetic
-
-    time_point& operator+=(const duration& d); // constexpr in C++17
-    time_point& operator-=(const duration& d); // constexpr in C++17
-
-    // special values
-
-    static constexpr time_point min();  // noexcept in C++20
-    static constexpr time_point max();  // noexcept in C++20
-};
-
-} // chrono
-
-// common_type traits
-template <class Rep1, class Period1, class Rep2, class Period2>
-  struct common_type<chrono::duration<Rep1, Period1>, chrono::duration<Rep2, Period2>>;
-
-template <class Clock, class Duration1, class Duration2>
-  struct common_type<chrono::time_point<Clock, Duration1>, chrono::time_point<Clock, Duration2>>;
-
-namespace chrono {
-
-
-template<class T> struct is_clock;  // C++20
-template<class T> inline constexpr bool is_clock_v = is_clock<T>::value;   // C++20
-
-
-// duration arithmetic
-template <class Rep1, class Period1, class Rep2, class Period2>
-  constexpr
-  typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
-  operator+(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Rep2, class Period2>
-  constexpr
-  typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
-  operator-(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period, class Rep2>
-  constexpr
-  duration<typename common_type<Rep1, Rep2>::type, Period>
-  operator*(const duration<Rep1, Period>& d, const Rep2& s);
-template <class Rep1, class Period, class Rep2>
-  constexpr
-  duration<typename common_type<Rep1, Rep2>::type, Period>
-  operator*(const Rep1& s, const duration<Rep2, Period>& d);
-template <class Rep1, class Period, class Rep2>
-  constexpr
-  duration<typename common_type<Rep1, Rep2>::type, Period>
-  operator/(const duration<Rep1, Period>& d, const Rep2& s);
-template <class Rep1, class Period1, class Rep2, class Period2>
-  constexpr
-  typename common_type<Rep1, Rep2>::type
-  operator/(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-
-// duration comparisons
-template <class Rep1, class Period1, class Rep2, class Period2>
-   constexpr
-   bool operator==(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Rep2, class Period2>
-   constexpr
-   bool operator!=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Rep2, class Period2>
-   constexpr
-   bool operator< (const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Rep2, class Period2>
-   constexpr
-   bool operator<=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Rep2, class Period2>
-   constexpr
-   bool operator> (const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Rep2, class Period2>
-   constexpr
-   bool operator>=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
-
-// duration_cast
-template <class ToDuration, class Rep, class Period>
-  ToDuration duration_cast(const duration<Rep, Period>& d);
-
-template <class ToDuration, class Rep, class Period>
-    constexpr ToDuration floor(const duration<Rep, Period>& d);    // C++17
-template <class ToDuration, class Rep, class Period>
-    constexpr ToDuration ceil(const duration<Rep, Period>& d);     // C++17
-template <class ToDuration, class Rep, class Period>
-    constexpr ToDuration round(const duration<Rep, Period>& d);    // C++17
-
-// duration I/O is elsewhere
-
-// time_point arithmetic (all constexpr in C++14)
-template <class Clock, class Duration1, class Rep2, class Period2>
-  time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
-  operator+(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Rep1, class Period1, class Clock, class Duration2>
-  time_point<Clock, typename common_type<duration<Rep1, Period1>, Duration2>::type>
-  operator+(const duration<Rep1, Period1>& lhs, const time_point<Clock, Duration2>& rhs);
-template <class Clock, class Duration1, class Rep2, class Period2>
-  time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
-  operator-(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
-template <class Clock, class Duration1, class Duration2>
-  typename common_type<Duration1, Duration2>::type
-  operator-(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-
-// time_point comparisons (all constexpr in C++14)
-template <class Clock, class Duration1, class Duration2>
-   bool operator==(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-template <class Clock, class Duration1, class Duration2>
-   bool operator!=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-template <class Clock, class Duration1, class Duration2>
-   bool operator< (const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-template <class Clock, class Duration1, class Duration2>
-   bool operator<=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-template <class Clock, class Duration1, class Duration2>
-   bool operator> (const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-template <class Clock, class Duration1, class Duration2>
-   bool operator>=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
-
-// time_point_cast (constexpr in C++14)
-
-template <class ToDuration, class Clock, class Duration>
-  time_point<Clock, ToDuration> time_point_cast(const time_point<Clock, Duration>& t);
-
-template <class ToDuration, class Clock, class Duration>
-    constexpr time_point<Clock, ToDuration>
-    floor(const time_point<Clock, Duration>& tp);                  // C++17
-
-template <class ToDuration, class Clock, class Duration>
-    constexpr time_point<Clock, ToDuration>
-    ceil(const time_point<Clock, Duration>& tp);                   // C++17
-
-template <class ToDuration, class Clock, class Duration>
-    constexpr time_point<Clock, ToDuration>
-    round(const time_point<Clock, Duration>& tp);                  // C++17
-
-template <class Rep, class Period>
-    constexpr duration<Rep, Period> abs(duration<Rep, Period> d);  // C++17
-
-// Clocks
-
-class system_clock
-{
-public:
-    typedef microseconds                     duration;
-    typedef duration::rep                    rep;
-    typedef duration::period                 period;
-    typedef chrono::time_point<system_clock> time_point;
-    static const bool is_steady =            false; // constexpr in C++14
-
-    static time_point now() noexcept;
-    static time_t     to_time_t  (const time_point& __t) noexcept;
-    static time_point from_time_t(time_t __t) noexcept;
-};
-
-template <class Duration>
-  using sys_time  = time_point<system_clock, Duration>; // C++20
-using sys_seconds = sys_time<seconds>;                  // C++20
-using sys_days    = sys_time<days>;                     // C++20
-
-class utc_clock;                                        // C++20
-
-template <class Duration>
-  using utc_time  = time_point<utc_clock, Duration>;    // C++20
-using utc_seconds = utc_time<seconds>;                  // C++20
-
-class tai_clock;                                        // C++20
-
-template <class Duration>
-  using tai_time  = time_point<tai_clock, Duration>;    // C++20
-using tai_seconds = tai_time<seconds>;                  // C++20
-
-class file_clock;                                       // C++20
-
-template<class Duration>
-  using file_time = time_point<file_clock, Duration>;   // C++20
-
-class steady_clock
-{
-public:
-    typedef nanoseconds                                   duration;
-    typedef duration::rep                                 rep;
-    typedef duration::period                              period;
-    typedef chrono::time_point<steady_clock, duration>    time_point;
-    static const bool is_steady =                         true; // constexpr in C++14
-
-    static time_point now() noexcept;
-};
-
-typedef steady_clock high_resolution_clock;
-
-// 25.7.8, local time           // C++20
-struct local_t {};
-template<class Duration>
-  using local_time  = time_point<local_t, Duration>;
-using local_seconds = local_time<seconds>;
-using local_days    = local_time<days>;
-
-// 25.7.9, time_point conversions template<class DestClock, class SourceClock>    // C++20
-struct clock_time_conversion;
-
-template<class DestClock, class SourceClock, class Duration>
-  auto clock_cast(const time_point<SourceClock, Duration>& t);
-
-// 25.8.2, class last_spec    // C++20
-struct last_spec;
-
-// 25.8.3, class day          // C++20
-
-class day;
-constexpr bool operator==(const day& x, const day& y) noexcept;
-constexpr bool operator!=(const day& x, const day& y) noexcept;
-constexpr bool operator< (const day& x, const day& y) noexcept;
-constexpr bool operator> (const day& x, const day& y) noexcept;
-constexpr bool operator<=(const day& x, const day& y) noexcept;
-constexpr bool operator>=(const day& x, const day& y) noexcept;
-constexpr day  operator+(const day&  x, const days& y) noexcept;
-constexpr day  operator+(const days& x, const day&  y) noexcept;
-constexpr day  operator-(const day&  x, const days& y) noexcept;
-constexpr days operator-(const day&  x, const day&  y) noexcept;
-
-// 25.8.4, class month    // C++20
-class month;
-constexpr bool operator==(const month& x, const month& y) noexcept;
-constexpr bool operator!=(const month& x, const month& y) noexcept;
-constexpr bool operator< (const month& x, const month& y) noexcept;
-constexpr bool operator> (const month& x, const month& y) noexcept;
-constexpr bool operator<=(const month& x, const month& y) noexcept;
-constexpr bool operator>=(const month& x, const month& y) noexcept;
-constexpr month  operator+(const month&  x, const months& y) noexcept;
-constexpr month  operator+(const months& x,  const month& y) noexcept;
-constexpr month  operator-(const month&  x, const months& y) noexcept;
-constexpr months operator-(const month&  x,  const month& y) noexcept;
-
-// 25.8.5, class year    // C++20
-class year;
-constexpr bool operator==(const year& x, const year& y) noexcept;
-constexpr bool operator!=(const year& x, const year& y) noexcept;
-constexpr bool operator< (const year& x, const year& y) noexcept;
-constexpr bool operator> (const year& x, const year& y) noexcept;
-constexpr bool operator<=(const year& x, const year& y) noexcept;
-constexpr bool operator>=(const year& x, const year& y) noexcept;
-constexpr year  operator+(const year&  x, const years& y) noexcept;
-constexpr year  operator+(const years& x, const year&  y) noexcept;
-constexpr year  operator-(const year&  x, const years& y) noexcept;
-constexpr years operator-(const year&  x, const year&  y) noexcept;
-
-// 25.8.6, class weekday    // C++20
-class weekday;
-
-constexpr bool operator==(const weekday& x, const weekday& y) noexcept;
-constexpr bool operator!=(const weekday& x, const weekday& y) noexcept;
-constexpr weekday operator+(const weekday& x, const days&    y) noexcept;
-constexpr weekday operator+(const days&    x, const weekday& y) noexcept;
-constexpr weekday operator-(const weekday& x, const days&    y) noexcept;
-constexpr days    operator-(const weekday& x, const weekday& y) noexcept;
-
-// 25.8.7, class weekday_indexed    // C++20
-
-class weekday_indexed;
-constexpr bool operator==(const weekday_indexed& x, const weekday_indexed& y) noexcept;
-constexpr bool operator!=(const weekday_indexed& x, const weekday_indexed& y) noexcept;
-
-// 25.8.8, class weekday_last    // C++20
-class weekday_last;
-
-constexpr bool operator==(const weekday_last& x, const weekday_last& y) noexcept;
-constexpr bool operator!=(const weekday_last& x, const weekday_last& y) noexcept;
-
-// 25.8.9, class month_day    // C++20
-class month_day;
-
-constexpr bool operator==(const month_day& x, const month_day& y) noexcept;
-constexpr bool operator!=(const month_day& x, const month_day& y) noexcept;
-constexpr bool operator< (const month_day& x, const month_day& y) noexcept;
-constexpr bool operator> (const month_day& x, const month_day& y) noexcept;
-constexpr bool operator<=(const month_day& x, const month_day& y) noexcept;
-constexpr bool operator>=(const month_day& x, const month_day& y) noexcept;
-
-
-// 25.8.10, class month_day_last    // C++20
-class month_day_last;
-
-constexpr bool operator==(const month_day_last& x, const month_day_last& y) noexcept;
-constexpr bool operator!=(const month_day_last& x, const month_day_last& y) noexcept;
-constexpr bool operator< (const month_day_last& x, const month_day_last& y) noexcept;
-constexpr bool operator> (const month_day_last& x, const month_day_last& y) noexcept;
-constexpr bool operator<=(const month_day_last& x, const month_day_last& y) noexcept;
-constexpr bool operator>=(const month_day_last& x, const month_day_last& y) noexcept;
-
-// 25.8.11, class month_weekday    // C++20
-class month_weekday;
-
-constexpr bool operator==(const month_weekday& x, const month_weekday& y) noexcept;
-constexpr bool operator!=(const month_weekday& x, const month_weekday& y) noexcept;
-
-// 25.8.12, class month_weekday_last    // C++20
-class month_weekday_last;
-
-constexpr bool operator==(const month_weekday_last& x, const month_weekday_last& y) noexcept;
-constexpr bool operator!=(const month_weekday_last& x, const month_weekday_last& y) noexcept;
-
-
-// 25.8.13, class year_month    // C++20
-class year_month;
-
-constexpr bool operator==(const year_month& x, const year_month& y) noexcept;
-constexpr bool operator!=(const year_month& x, const year_month& y) noexcept;
-constexpr bool operator< (const year_month& x, const year_month& y) noexcept;
-constexpr bool operator> (const year_month& x, const year_month& y) noexcept;
-constexpr bool operator<=(const year_month& x, const year_month& y) noexcept;
-constexpr bool operator>=(const year_month& x, const year_month& y) noexcept;
-
-constexpr year_month operator+(const year_month& ym, const months& dm) noexcept;
-constexpr year_month operator+(const months& dm, const year_month& ym) noexcept;
-constexpr year_month operator-(const year_month& ym, const months& dm) noexcept;
-constexpr months operator-(const year_month& x, const year_month& y) noexcept;
-constexpr year_month operator+(const year_month& ym, const years& dy) noexcept;
-constexpr year_month operator+(const years& dy, const year_month& ym) noexcept;
-constexpr year_month operator-(const year_month& ym, const years& dy) noexcept;
-
-// 25.8.14, class year_month_day class    // C++20
-year_month_day;
-
-constexpr bool operator==(const year_month_day& x, const year_month_day& y) noexcept;
-constexpr bool operator!=(const year_month_day& x, const year_month_day& y) noexcept;
-constexpr bool operator< (const year_month_day& x, const year_month_day& y) noexcept;
-constexpr bool operator> (const year_month_day& x, const year_month_day& y) noexcept;
-constexpr bool operator<=(const year_month_day& x, const year_month_day& y) noexcept;
-constexpr bool operator>=(const year_month_day& x, const year_month_day& y) noexcept;
-
-constexpr year_month_day operator+(const year_month_day& ymd, const months& dm) noexcept;
-constexpr year_month_day operator+(const months& dm, const year_month_day& ymd) noexcept;
-constexpr year_month_day operator+(const year_month_day& ymd, const years& dy) noexcept;
-constexpr year_month_day operator+(const years& dy, const year_month_day& ymd) noexcept;
-constexpr year_month_day operator-(const year_month_day& ymd, const months& dm) noexcept;
-constexpr year_month_day operator-(const year_month_day& ymd, const years& dy) noexcept;
-
-
-// 25.8.15, class year_month_day_last    // C++20
-class year_month_day_last;
-
-constexpr bool operator==(const year_month_day_last& x,
-                          const year_month_day_last& y) noexcept;
-constexpr bool operator!=(const year_month_day_last& x,
-                          const year_month_day_last& y) noexcept;
-constexpr bool operator< (const year_month_day_last& x,
-                          const year_month_day_last& y) noexcept;
-constexpr bool operator> (const year_month_day_last& x,
-                          const year_month_day_last& y) noexcept;
-constexpr bool operator<=(const year_month_day_last& x,
-                          const year_month_day_last& y) noexcept;
-constexpr bool operator>=(const year_month_day_last& x,
-                          const year_month_day_last& y) noexcept;
-
-constexpr year_month_day_last
-  operator+(const year_month_day_last& ymdl, const months& dm) noexcept;
-constexpr year_month_day_last
-  operator+(const months& dm, const year_month_day_last& ymdl) noexcept;
-constexpr year_month_day_last
-  operator+(const year_month_day_last& ymdl, const years& dy) noexcept;
-constexpr year_month_day_last
-  operator+(const years& dy, const year_month_day_last& ymdl) noexcept;
-constexpr year_month_day_last
-  operator-(const year_month_day_last& ymdl, const months& dm) noexcept;
-constexpr year_month_day_last
-  operator-(const year_month_day_last& ymdl, const years& dy) noexcept;
-
-// 25.8.16, class year_month_weekday    // C++20
-class year_month_weekday;
-
-constexpr bool operator==(const year_month_weekday& x,
-                          const year_month_weekday& y) noexcept;
-constexpr bool operator!=(const year_month_weekday& x,
-                          const year_month_weekday& y) noexcept;
-
-constexpr year_month_weekday
-  operator+(const year_month_weekday& ymwd, const months& dm) noexcept;
-constexpr year_month_weekday
-  operator+(const months& dm, const year_month_weekday& ymwd) noexcept;
-constexpr year_month_weekday
-  operator+(const year_month_weekday& ymwd, const years& dy) noexcept;
-constexpr year_month_weekday
-  operator+(const years& dy, const year_month_weekday& ymwd) noexcept;
-constexpr year_month_weekday
-  operator-(const year_month_weekday& ymwd, const months& dm) noexcept;
-constexpr year_month_weekday
-  operator-(const year_month_weekday& ymwd, const years& dy) noexcept;
-
-// 25.8.17, class year_month_weekday_last    // C++20
-class year_month_weekday_last;
-
-constexpr bool operator==(const year_month_weekday_last& x,
-                          const year_month_weekday_last& y) noexcept;
-constexpr bool operator!=(const year_month_weekday_last& x,
-                          const year_month_weekday_last& y) noexcept;
-constexpr year_month_weekday_last
-  operator+(const year_month_weekday_last& ymwdl, const months& dm) noexcept;
-constexpr year_month_weekday_last
-  operator+(const months& dm, const year_month_weekday_last& ymwdl) noexcept;
-constexpr year_month_weekday_last
-  operator+(const year_month_weekday_last& ymwdl, const years& dy) noexcept;
-constexpr year_month_weekday_last
-  operator+(const years& dy, const year_month_weekday_last& ymwdl) noexcept;
-constexpr year_month_weekday_last
-  operator-(const year_month_weekday_last& ymwdl, const months& dm) noexcept;
-constexpr year_month_weekday_last
-  operator-(const year_month_weekday_last& ymwdl, const years& dy) noexcept;
-
-// 25.8.18, civil calendar conventional syntax operators    // C++20
-constexpr year_month
-  operator/(const year& y, const month& m) noexcept;
-constexpr year_month
-  operator/(const year& y, int m) noexcept;
-constexpr month_day
-  operator/(const month& m, const day& d) noexcept;
-constexpr month_day
-  operator/(const month& m, int d) noexcept;
-constexpr month_day
-  operator/(int m, const day& d) noexcept;
-constexpr month_day
-  operator/(const day& d, const month& m) noexcept;
-constexpr month_day
-  operator/(const day& d, int m) noexcept;
-constexpr month_day_last
-  operator/(const month& m, last_spec) noexcept;
-constexpr month_day_last
-  operator/(int m, last_spec) noexcept;
-constexpr month_day_last
-  operator/(last_spec, const month& m) noexcept;
-constexpr month_day_last
-  operator/(last_spec, int m) noexcept;
-constexpr month_weekday
-  operator/(const month& m, const weekday_indexed& wdi) noexcept;
-constexpr month_weekday
-  operator/(int m, const weekday_indexed& wdi) noexcept;
-constexpr month_weekday
-  operator/(const weekday_indexed& wdi, const month& m) noexcept;
-constexpr month_weekday
-  operator/(const weekday_indexed& wdi, int m) noexcept;
-constexpr month_weekday_last
-  operator/(const month& m, const weekday_last& wdl) noexcept;
-constexpr month_weekday_last
-  operator/(int m, const weekday_last& wdl) noexcept;
-constexpr month_weekday_last
-  operator/(const weekday_last& wdl, const month& m) noexcept;
-constexpr month_weekday_last
-  operator/(const weekday_last& wdl, int m) noexcept;
-constexpr year_month_day
-  operator/(const year_month& ym, const day& d) noexcept;
-constexpr year_month_day
-  operator/(const year_month& ym, int d) noexcept;
-constexpr year_month_day
-  operator/(const year& y, const month_day& md) noexcept;
-constexpr year_month_day
-  operator/(int y, const month_day& md) noexcept;
-constexpr year_month_day
-  operator/(const month_day& md, const year& y) noexcept;
-constexpr year_month_day
-  operator/(const month_day& md, int y) noexcept;
-constexpr year_month_day_last
-  operator/(const year_month& ym, last_spec) noexcept;
-constexpr year_month_day_last
-  operator/(const year& y, const month_day_last& mdl) noexcept;
-constexpr year_month_day_last
-  operator/(int y, const month_day_last& mdl) noexcept;
-constexpr year_month_day_last
-  operator/(const month_day_last& mdl, const year& y) noexcept;
-constexpr year_month_day_last
-  operator/(const month_day_last& mdl, int y) noexcept;
-constexpr year_month_weekday
-  operator/(const year_month& ym, const weekday_indexed& wdi) noexcept;
-constexpr year_month_weekday
-  operator/(const year& y, const month_weekday& mwd) noexcept;
-constexpr year_month_weekday
-  operator/(int y, const month_weekday& mwd) noexcept;
-constexpr year_month_weekday
-  operator/(const month_weekday& mwd, const year& y) noexcept;
-constexpr year_month_weekday
-  operator/(const month_weekday& mwd, int y) noexcept;
-constexpr year_month_weekday_last
-  operator/(const year_month& ym, const weekday_last& wdl) noexcept;
-constexpr year_month_weekday_last
-  operator/(const year& y, const month_weekday_last& mwdl) noexcept;
-constexpr year_month_weekday_last
-  operator/(int y, const month_weekday_last& mwdl) noexcept;
-constexpr year_month_weekday_last
-  operator/(const month_weekday_last& mwdl, const year& y) noexcept;
-constexpr year_month_weekday_last
-  operator/(const month_weekday_last& mwdl, int y) noexcept;
-
-// 26.9, class template hh_mm_ss
-template <class Duration>
-class hh_mm_ss
-{
-    bool            is_neg; // exposition only
-    chrono::hours   h;      // exposition only
-    chrono::minutes m;      // exposition only
-    chrono::seconds s;      // exposition only
-    precision       ss;     // exposition only
-
-public:
-    static unsigned constexpr fractional_width = see below;
-    using precision                            = see below;
-
-    constexpr hh_mm_ss() noexcept : hh_mm_ss{Duration::zero()} {}
-    constexpr explicit hh_mm_ss(Duration d) noexcept;
-
-    constexpr bool is_negative() const noexcept;
-    constexpr chrono::hours hours() const noexcept;
-    constexpr chrono::minutes minutes() const noexcept;
-    constexpr chrono::seconds seconds() const noexcept;
-    constexpr precision subseconds() const noexcept;
-
-    constexpr explicit operator  precision()   const noexcept;
-    constexpr          precision to_duration() const noexcept;
-};
-
-template <class charT, class traits, class Duration>
-  basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os, hh_mm_ss<Duration> const& hms);
-
-// 26.10, 12/24 hour functions
-constexpr bool is_am(hours const& h) noexcept;
-constexpr bool is_pm(hours const& h) noexcept;
-constexpr hours make12(const hours& h) noexcept;
-constexpr hours make24(const hours& h, bool is_pm) noexcept;
-
-
-// 25.10.2, time zone database     // C++20
-struct tzdb;
-class tzdb_list;
-
-// 25.10.2.3, time zone database access    // C++20
-const tzdb& get_tzdb();
-tzdb_list& get_tzdb_list();
-const time_zone* locate_zone(string_view tz_name);
-const time_zone* current_zone();
-
-// 25.10.2.4, remote time zone database support    // C++20
-const tzdb& reload_tzdb();
-string remote_version();
-
-// 25.10.3, exception classes    // C++20
-class nonexistent_local_time;
-class ambiguous_local_time;
-
-// 25.10.4, information classes    // C++20
-struct sys_info;
-struct local_info;
-
-// 25.10.5, class time_zone    // C++20
-enum class choose {earliest, latest};
-class time_zone;
-bool operator==(const time_zone& x, const time_zone& y) noexcept;
-bool operator!=(const time_zone& x, const time_zone& y) noexcept;
-bool operator<(const time_zone& x, const time_zone& y) noexcept;
-bool operator>(const time_zone& x, const time_zone& y) noexcept;
-bool operator<=(const time_zone& x, const time_zone& y) noexcept;
-bool operator>=(const time_zone& x, const time_zone& y) noexcept;
-
-// 25.10.6, class template zoned_traits    // C++20
-template<class T> struct zoned_traits;
-
-// 25.10.7, class template zoned_time    // C++20
-template<class Duration, class TimeZonePtr = const time_zone*> class zoned_time;
-using zoned_seconds = zoned_time<seconds>;
-
-template<class Duration1, class Duration2, class TimeZonePtr>
-  bool operator==(const zoned_time<Duration1, TimeZonePtr>& x,
-                  const zoned_time<Duration2, TimeZonePtr>& y);
-template<class Duration1, class Duration2, class TimeZonePtr>
-  bool operator!=(const zoned_time<Duration1, TimeZonePtr>& x,
-                  const zoned_time<Duration2, TimeZonePtr>& y);
-
-// 25.10.8, leap second support    // C++20
-class leap;
-
-bool operator==(const leap& x, const leap& y);
-bool operator!=(const leap& x, const leap& y);
-bool operator< (const leap& x, const leap& y);
-bool operator> (const leap& x, const leap& y);
-bool operator<=(const leap& x, const leap& y);
-bool operator>=(const leap& x, const leap& y);
-template<class Duration>
-  bool operator==(const leap& x, const sys_time<Duration>& y);
-template<class Duration>
-  bool operator==(const sys_time<Duration>& x, const leap& y);
-template<class Duration>
-  bool operator!=(const leap& x, const sys_time<Duration>& y);
-template<class Duration>
-  bool operator!=(const sys_time<Duration>& x, const leap& y);
-template<class Duration>
-  bool operator< (const leap& x, const sys_time<Duration>& y);
-template<class Duration>
-  bool operator< (const sys_time<Duration>& x, const leap& y);
-template<class Duration>
-  bool operator> (const leap& x, const sys_time<Duration>& y);
-template<class Duration>
-  bool operator> (const sys_time<Duration>& x, const leap& y);
-template<class Duration>
-  bool operator<=(const leap& x, const sys_time<Duration>& y);
-template<class Duration>
-  bool operator<=(const sys_time<Duration>& x, const leap& y);
-template<class Duration>
-  bool operator>=(const leap& x, const sys_time<Duration>& y);
-template<class Duration>
-  bool operator>=(const sys_time<Duration>& x, const leap& y);
-
-// 25.10.9, class link    // C++20
-class link;
-bool operator==(const link& x, const link& y);
-bool operator!=(const link& x, const link& y);
-bool operator< (const link& x, const link& y);
-bool operator> (const link& x, const link& y);
-bool operator<=(const link& x, const link& y);
-bool operator>=(const link& x, const link& y);
-
-// 25.11, formatting    // C++20
-template<class charT, class Streamable>
-  basic_string<charT>
-    format(const charT* fmt, const Streamable& s);
-
-template<class charT, class Streamable>
-  basic_string<charT>
-    format(const locale& loc, const charT* fmt, const Streamable& s);
-
-template<class charT, class traits, class Alloc, class Streamable>
-  basic_string<charT, traits, Alloc>
-    format(const basic_string<charT, traits, Alloc>& fmt, const Streamable& s);
-
-template<class charT, class traits, class Alloc, class Streamable>
-  basic_string<charT, traits, Alloc>
-    format(const locale& loc, const basic_string<charT, traits, Alloc>& fmt,
-           const Streamable& s);
-
-// 25.12, parsing    // C++20
-template<class charT, class traits, class Alloc, class Parsable>
-unspecified
-    parse(const basic_string<charT, traits, Alloc>& format, Parsable& tp);
-
-template<class charT, class traits, class Alloc, class Parsable>
-unspecified
-    parse(const basic_string<charT, traits, Alloc>& format, Parsable& tp,
-          basic_string<charT, traits, Alloc>& abbrev);
-
-template<class charT, class traits, class Alloc, class Parsable>
-unspecified
-    parse(const basic_string<charT, traits, Alloc>& format, Parsable& tp,
-          minutes& offset);
-
-template<class charT, class traits, class Alloc, class Parsable>
-unspecified
-    parse(const basic_string<charT, traits, Alloc>& format, Parsable& tp,
-          basic_string<charT, traits, Alloc>& abbrev, minutes& offset);
-
-// calendrical constants
-inline constexpr last_spec                              last{};       // C++20
-inline constexpr chrono::weekday                        Sunday{0};    // C++20
-inline constexpr chrono::weekday                        Monday{1};    // C++20
-inline constexpr chrono::weekday                        Tuesday{2};   // C++20
-inline constexpr chrono::weekday                        Wednesday{3}; // C++20
-inline constexpr chrono::weekday                        Thursday{4};  // C++20
-inline constexpr chrono::weekday                        Friday{5};    // C++20
-inline constexpr chrono::weekday                        Saturday{6};  // C++20
-
-inline constexpr chrono::month                          January{1};   // C++20
-inline constexpr chrono::month                          February{2};  // C++20
-inline constexpr chrono::month                          March{3};     // C++20
-inline constexpr chrono::month                          April{4};     // C++20
-inline constexpr chrono::month                          May{5};       // C++20
-inline constexpr chrono::month                          June{6};      // C++20
-inline constexpr chrono::month                          July{7};      // C++20
-inline constexpr chrono::month                          August{8};    // C++20
-inline constexpr chrono::month                          September{9}; // C++20
-inline constexpr chrono::month                          October{10};  // C++20
-inline constexpr chrono::month                          November{11}; // C++20
-inline constexpr chrono::month                          December{12}; // C++20
-}  // chrono
-
-inline namespace literals {
-  inline namespace chrono_literals {
-constexpr chrono::hours                                 operator ""h(unsigned long long); // C++14
-constexpr chrono::duration<unspecified , ratio<3600,1>> operator ""h(long double); // C++14
-constexpr chrono::minutes                               operator ""min(unsigned long long); // C++14
-constexpr chrono::duration<unspecified , ratio<60,1>>   operator ""min(long double); // C++14
-constexpr chrono::seconds                               operator ""s(unsigned long long); // C++14
-constexpr chrono::duration<unspecified >                operator ""s(long double); // C++14
-constexpr chrono::milliseconds                          operator ""ms(unsigned long long); // C++14
-constexpr chrono::duration<unspecified , milli>         operator ""ms(long double); // C++14
-constexpr chrono::microseconds                          operator ""us(unsigned long long); // C++14
-constexpr chrono::duration<unspecified , micro>         operator ""us(long double); // C++14
-constexpr chrono::nanoseconds                           operator ""ns(unsigned long long); // C++14
-constexpr chrono::duration<unspecified , nano>          operator ""ns(long double); // C++14
-constexpr chrono::day                                   operator ""d(unsigned long long d) noexcept; // C++20
-constexpr chrono::year                                  operator ""y(unsigned long long y) noexcept; // C++20
-}  // chrono_literals
-}  // literals
-
-}  // std
-*/
+// Synopsis avaiable at http://wg21.link/time.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/climits b/libcxx/include/climits
--- a/libcxx/include/climits
+++ b/libcxx/include/climits
@@ -10,32 +10,7 @@
 #ifndef _LIBCPP_CLIMITS
 #define _LIBCPP_CLIMITS
 
-/*
-    climits synopsis
-
-Macros:
-
-    CHAR_BIT
-    SCHAR_MIN
-    SCHAR_MAX
-    UCHAR_MAX
-    CHAR_MIN
-    CHAR_MAX
-    MB_LEN_MAX
-    SHRT_MIN
-    SHRT_MAX
-    USHRT_MAX
-    INT_MIN
-    INT_MAX
-    UINT_MAX
-    LONG_MIN
-    LONG_MAX
-    ULONG_MAX
-    LLONG_MIN   // C99
-    LLONG_MAX   // C99
-    ULLONG_MAX  // C99
-
-*/
+// Synopsis avaiable at http://wg21.link/climits.syn.
 
 #include <__config>
 #include <limits.h>
diff --git a/libcxx/include/clocale b/libcxx/include/clocale
--- a/libcxx/include/clocale
+++ b/libcxx/include/clocale
@@ -10,29 +10,7 @@
 #ifndef _LIBCPP_CLOCALE
 #define _LIBCPP_CLOCALE
 
-/*
-    clocale synopsis
-
-Macros:
-
-    LC_ALL
-    LC_COLLATE
-    LC_CTYPE
-    LC_MONETARY
-    LC_NUMERIC
-    LC_TIME
-    NULL
-
-namespace std
-{
-
-struct lconv;
-char* setlocale(int category, const char* locale);
-lconv* localeconv();
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/clocale.syn.
 
 #include <__config>
 #include <locale.h>
diff --git a/libcxx/include/cmath b/libcxx/include/cmath
--- a/libcxx/include/cmath
+++ b/libcxx/include/cmath
@@ -10,299 +10,7 @@
 #ifndef _LIBCPP_CMATH
 #define _LIBCPP_CMATH
 
-/*
-    cmath synopsis
-
-Macros:
-
-    HUGE_VAL
-    HUGE_VALF               // C99
-    HUGE_VALL               // C99
-    INFINITY                // C99
-    NAN                     // C99
-    FP_INFINITE             // C99
-    FP_NAN                  // C99
-    FP_NORMAL               // C99
-    FP_SUBNORMAL            // C99
-    FP_ZERO                 // C99
-    FP_FAST_FMA             // C99
-    FP_FAST_FMAF            // C99
-    FP_FAST_FMAL            // C99
-    FP_ILOGB0               // C99
-    FP_ILOGBNAN             // C99
-    MATH_ERRNO              // C99
-    MATH_ERREXCEPT          // C99
-    math_errhandling        // C99
-
-namespace std
-{
-
-Types:
-
-    float_t                 // C99
-    double_t                // C99
-
-// C90
-
-floating_point abs(floating_point x);
-
-floating_point acos (arithmetic x);
-float          acosf(float x);
-long double    acosl(long double x);
-
-floating_point asin (arithmetic x);
-float          asinf(float x);
-long double    asinl(long double x);
-
-floating_point atan (arithmetic x);
-float          atanf(float x);
-long double    atanl(long double x);
-
-floating_point atan2 (arithmetic y, arithmetic x);
-float          atan2f(float y, float x);
-long double    atan2l(long double y, long double x);
-
-floating_point ceil (arithmetic x);
-float          ceilf(float x);
-long double    ceill(long double x);
-
-floating_point cos (arithmetic x);
-float          cosf(float x);
-long double    cosl(long double x);
-
-floating_point cosh (arithmetic x);
-float          coshf(float x);
-long double    coshl(long double x);
-
-floating_point exp (arithmetic x);
-float          expf(float x);
-long double    expl(long double x);
-
-floating_point fabs (arithmetic x);
-float          fabsf(float x);
-long double    fabsl(long double x);
-
-floating_point floor (arithmetic x);
-float          floorf(float x);
-long double    floorl(long double x);
-
-floating_point fmod (arithmetic x, arithmetic y);
-float          fmodf(float x, float y);
-long double    fmodl(long double x, long double y);
-
-floating_point frexp (arithmetic value, int* exp);
-float          frexpf(float value, int* exp);
-long double    frexpl(long double value, int* exp);
-
-floating_point ldexp (arithmetic value, int exp);
-float          ldexpf(float value, int exp);
-long double    ldexpl(long double value, int exp);
-
-floating_point log (arithmetic x);
-float          logf(float x);
-long double    logl(long double x);
-
-floating_point log10 (arithmetic x);
-float          log10f(float x);
-long double    log10l(long double x);
-
-floating_point modf (floating_point value, floating_point* iptr);
-float          modff(float value, float* iptr);
-long double    modfl(long double value, long double* iptr);
-
-floating_point pow (arithmetic x, arithmetic y);
-float          powf(float x, float y);
-long double    powl(long double x, long double y);
-
-floating_point sin (arithmetic x);
-float          sinf(float x);
-long double    sinl(long double x);
-
-floating_point sinh (arithmetic x);
-float          sinhf(float x);
-long double    sinhl(long double x);
-
-floating_point sqrt (arithmetic x);
-float          sqrtf(float x);
-long double    sqrtl(long double x);
-
-floating_point tan (arithmetic x);
-float          tanf(float x);
-long double    tanl(long double x);
-
-floating_point tanh (arithmetic x);
-float          tanhf(float x);
-long double    tanhl(long double x);
-
-//  C99
-
-bool signbit(arithmetic x);
-
-int fpclassify(arithmetic x);
-
-bool isfinite(arithmetic x);
-bool isinf(arithmetic x);
-bool isnan(arithmetic x);
-bool isnormal(arithmetic x);
-
-bool isgreater(arithmetic x, arithmetic y);
-bool isgreaterequal(arithmetic x, arithmetic y);
-bool isless(arithmetic x, arithmetic y);
-bool islessequal(arithmetic x, arithmetic y);
-bool islessgreater(arithmetic x, arithmetic y);
-bool isunordered(arithmetic x, arithmetic y);
-
-floating_point acosh (arithmetic x);
-float          acoshf(float x);
-long double    acoshl(long double x);
-
-floating_point asinh (arithmetic x);
-float          asinhf(float x);
-long double    asinhl(long double x);
-
-floating_point atanh (arithmetic x);
-float          atanhf(float x);
-long double    atanhl(long double x);
-
-floating_point cbrt (arithmetic x);
-float          cbrtf(float x);
-long double    cbrtl(long double x);
-
-floating_point copysign (arithmetic x, arithmetic y);
-float          copysignf(float x, float y);
-long double    copysignl(long double x, long double y);
-
-floating_point erf (arithmetic x);
-float          erff(float x);
-long double    erfl(long double x);
-
-floating_point erfc (arithmetic x);
-float          erfcf(float x);
-long double    erfcl(long double x);
-
-floating_point exp2 (arithmetic x);
-float          exp2f(float x);
-long double    exp2l(long double x);
-
-floating_point expm1 (arithmetic x);
-float          expm1f(float x);
-long double    expm1l(long double x);
-
-floating_point fdim (arithmetic x, arithmetic y);
-float          fdimf(float x, float y);
-long double    fdiml(long double x, long double y);
-
-floating_point fma (arithmetic x, arithmetic y, arithmetic z);
-float          fmaf(float x, float y, float z);
-long double    fmal(long double x, long double y, long double z);
-
-floating_point fmax (arithmetic x, arithmetic y);
-float          fmaxf(float x, float y);
-long double    fmaxl(long double x, long double y);
-
-floating_point fmin (arithmetic x, arithmetic y);
-float          fminf(float x, float y);
-long double    fminl(long double x, long double y);
-
-floating_point hypot (arithmetic x, arithmetic y);
-float          hypotf(float x, float y);
-long double    hypotl(long double x, long double y);
-
-double       hypot(double x, double y, double z);                // C++17
-float        hypot(float x, float y, float z);                   // C++17
-long double  hypot(long double x, long double y, long double z); // C++17
-
-int ilogb (arithmetic x);
-int ilogbf(float x);
-int ilogbl(long double x);
-
-floating_point lgamma (arithmetic x);
-float          lgammaf(float x);
-long double    lgammal(long double x);
-
-long long llrint (arithmetic x);
-long long llrintf(float x);
-long long llrintl(long double x);
-
-long long llround (arithmetic x);
-long long llroundf(float x);
-long long llroundl(long double x);
-
-floating_point log1p (arithmetic x);
-float          log1pf(float x);
-long double    log1pl(long double x);
-
-floating_point log2 (arithmetic x);
-float          log2f(float x);
-long double    log2l(long double x);
-
-floating_point logb (arithmetic x);
-float          logbf(float x);
-long double    logbl(long double x);
-
-long lrint (arithmetic x);
-long lrintf(float x);
-long lrintl(long double x);
-
-long lround (arithmetic x);
-long lroundf(float x);
-long lroundl(long double x);
-
-double      nan (const char* str);
-float       nanf(const char* str);
-long double nanl(const char* str);
-
-floating_point nearbyint (arithmetic x);
-float          nearbyintf(float x);
-long double    nearbyintl(long double x);
-
-floating_point nextafter (arithmetic x, arithmetic y);
-float          nextafterf(float x, float y);
-long double    nextafterl(long double x, long double y);
-
-floating_point nexttoward (arithmetic x, long double y);
-float          nexttowardf(float x, long double y);
-long double    nexttowardl(long double x, long double y);
-
-floating_point remainder (arithmetic x, arithmetic y);
-float          remainderf(float x, float y);
-long double    remainderl(long double x, long double y);
-
-floating_point remquo (arithmetic x, arithmetic y, int* pquo);
-float          remquof(float x, float y, int* pquo);
-long double    remquol(long double x, long double y, int* pquo);
-
-floating_point rint (arithmetic x);
-float          rintf(float x);
-long double    rintl(long double x);
-
-floating_point round (arithmetic x);
-float          roundf(float x);
-long double    roundl(long double x);
-
-floating_point scalbln (arithmetic x, long ex);
-float          scalblnf(float x, long ex);
-long double    scalblnl(long double x, long ex);
-
-floating_point scalbn (arithmetic x, int ex);
-float          scalbnf(float x, int ex);
-long double    scalbnl(long double x, int ex);
-
-floating_point tgamma (arithmetic x);
-float          tgammaf(float x);
-long double    tgammal(long double x);
-
-floating_point trunc (arithmetic x);
-float          truncf(float x);
-long double    truncl(long double x);
-
-constexpr float       lerp(float a, float b, float t) noexcept;                   // C++20
-constexpr double      lerp(double a, double b, double t) noexcept;                // C++20
-constexpr long double lerp(long double a, long double b, long double t) noexcept; // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cmath.syn.
 
 #include <__config>
 #include <math.h>
diff --git a/libcxx/include/codecvt b/libcxx/include/codecvt
--- a/libcxx/include/codecvt
+++ b/libcxx/include/codecvt
@@ -10,49 +10,7 @@
 #ifndef _LIBCPP_CODECVT
 #define _LIBCPP_CODECVT
 
-/*
-    codecvt synopsis
-
-namespace std
-{
-
-enum codecvt_mode
-{
-    consume_header = 4,
-    generate_header = 2,
-    little_endian = 1
-};
-
-template <class Elem, unsigned long Maxcode = 0x10ffff,
-          codecvt_mode Mode = (codecvt_mode)0>
-class codecvt_utf8
-    : public codecvt<Elem, char, mbstate_t>
-{
-    explicit codecvt_utf8(size_t refs = 0);
-    ~codecvt_utf8();
-};
-
-template <class Elem, unsigned long Maxcode = 0x10ffff,
-          codecvt_mode Mode = (codecvt_mode)0>
-class codecvt_utf16
-    : public codecvt<Elem, char, mbstate_t>
-{
-    explicit codecvt_utf16(size_t refs = 0);
-    ~codecvt_utf16();
-};
-
-template <class Elem, unsigned long Maxcode = 0x10ffff,
-          codecvt_mode Mode = (codecvt_mode)0>
-class codecvt_utf8_utf16
-    : public codecvt<Elem, char, mbstate_t>
-{
-    explicit codecvt_utf8_utf16(size_t refs = 0);
-    ~codecvt_utf8_utf16();
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/locale.codecvt.general.
 
 #include <__config>
 #include <__locale>
diff --git a/libcxx/include/compare b/libcxx/include/compare
--- a/libcxx/include/compare
+++ b/libcxx/include/compare
@@ -10,115 +10,7 @@
 #ifndef _LIBCPP_COMPARE
 #define _LIBCPP_COMPARE
 
-/*
-    compare synopsis
-
-namespace std {
-  // [cmp.categories], comparison category types
-  class partial_ordering;
-  class weak_ordering;
-  class strong_ordering;
-
-  // named comparison functions
-  constexpr bool is_eq  (partial_ordering cmp) noexcept    { return cmp == 0; }
-  constexpr bool is_neq (partial_ordering cmp) noexcept    { return cmp != 0; }
-  constexpr bool is_lt  (partial_ordering cmp) noexcept { return cmp < 0; }
-  constexpr bool is_lteq(partial_ordering cmp) noexcept { return cmp <= 0; }
-  constexpr bool is_gt  (partial_ordering cmp) noexcept { return cmp > 0; }
-  constexpr bool is_gteq(partial_ordering cmp) noexcept { return cmp >= 0; }
-
-  // [cmp.common], common comparison category type
-  template<class... Ts>
-  struct common_comparison_category {
-    using type = see below;
-  };
-  template<class... Ts>
-    using common_comparison_category_t = typename common_comparison_category<Ts...>::type;
-
-  // [cmp.alg], comparison algorithms
-  template<class T> constexpr strong_ordering strong_order(const T& a, const T& b);
-  template<class T> constexpr weak_ordering weak_order(const T& a, const T& b);
-  template<class T> constexpr partial_ordering partial_order(const T& a, const T& b);
-
-  // [cmp.partialord], Class partial_ordering
-  class partial_ordering {
-  public:
-    // valid values
-    static const partial_ordering less;
-    static const partial_ordering equivalent;
-    static const partial_ordering greater;
-    static const partial_ordering unordered;
-
-    // comparisons
-    friend constexpr bool operator==(partial_ordering v, unspecified) noexcept;
-    friend constexpr bool operator==(partial_ordering v, partial_ordering w) noexcept = default;
-    friend constexpr bool operator< (partial_ordering v, unspecified) noexcept;
-    friend constexpr bool operator> (partial_ordering v, unspecified) noexcept;
-    friend constexpr bool operator<=(partial_ordering v, unspecified) noexcept;
-    friend constexpr bool operator>=(partial_ordering v, unspecified) noexcept;
-    friend constexpr bool operator< (unspecified, partial_ordering v) noexcept;
-    friend constexpr bool operator> (unspecified, partial_ordering v) noexcept;
-    friend constexpr bool operator<=(unspecified, partial_ordering v) noexcept;
-    friend constexpr bool operator>=(unspecified, partial_ordering v) noexcept;
-    friend constexpr partial_ordering operator<=>(partial_ordering v, unspecified) noexcept;
-    friend constexpr partial_ordering operator<=>(unspecified, partial_ordering v) noexcept;
-  };
-
-  // [cmp.weakord], Class weak_ordering
-  class weak_ordering {
-  public:
-    // valid values
-    static const weak_ordering less;
-    static const weak_ordering equivalent;
-    static const weak_ordering greater;
-
-    // conversions
-    constexpr operator partial_ordering() const noexcept;
-
-    // comparisons
-    friend constexpr bool operator==(weak_ordering v, unspecified) noexcept;
-    friend constexpr bool operator==(weak_ordering v, weak_ordering w) noexcept = default;
-    friend constexpr bool operator< (weak_ordering v, unspecified) noexcept;
-    friend constexpr bool operator> (weak_ordering v, unspecified) noexcept;
-    friend constexpr bool operator<=(weak_ordering v, unspecified) noexcept;
-    friend constexpr bool operator>=(weak_ordering v, unspecified) noexcept;
-    friend constexpr bool operator< (unspecified, weak_ordering v) noexcept;
-    friend constexpr bool operator> (unspecified, weak_ordering v) noexcept;
-    friend constexpr bool operator<=(unspecified, weak_ordering v) noexcept;
-    friend constexpr bool operator>=(unspecified, weak_ordering v) noexcept;
-    friend constexpr weak_ordering operator<=>(weak_ordering v, unspecified) noexcept;
-    friend constexpr weak_ordering operator<=>(unspecified, weak_ordering v) noexcept;
-  };
-
-  // [cmp.strongord], Class strong_ordering
-  class strong_ordering {
-  public:
-    // valid values
-    static const strong_ordering less;
-    static const strong_ordering equal;
-    static const strong_ordering equivalent;
-    static const strong_ordering greater;
-
-    // conversions
-    constexpr operator partial_ordering() const noexcept;
-    constexpr operator weak_ordering() const noexcept;
-
-    // comparisons
-    friend constexpr bool operator==(strong_ordering v, unspecified) noexcept;
-    friend constexpr bool operator==(strong_ordering v, strong_ordering w) noexcept = default;
-    friend constexpr bool operator< (strong_ordering v, unspecified) noexcept;
-    friend constexpr bool operator> (strong_ordering v, unspecified) noexcept;
-    friend constexpr bool operator<=(strong_ordering v, unspecified) noexcept;
-    friend constexpr bool operator>=(strong_ordering v, unspecified) noexcept;
-    friend constexpr bool operator< (unspecified, strong_ordering v) noexcept;
-    friend constexpr bool operator> (unspecified, strong_ordering v) noexcept;
-    friend constexpr bool operator<=(unspecified, strong_ordering v) noexcept;
-    friend constexpr bool operator>=(unspecified, strong_ordering v) noexcept;
-    friend constexpr strong_ordering operator<=>(strong_ordering v, unspecified) noexcept;
-    friend constexpr strong_ordering operator<=>(unspecified, strong_ordering v) noexcept;
-  };
-}
-*/
+// Synopsis avaiable at http://wg21.link/compare.syn.
 
 #include <__config>
 #include <type_traits>
diff --git a/libcxx/include/complex b/libcxx/include/complex
--- a/libcxx/include/complex
+++ b/libcxx/include/complex
@@ -10,226 +10,7 @@
 #ifndef _LIBCPP_COMPLEX
 #define _LIBCPP_COMPLEX
 
-/*
-    complex synopsis
-
-namespace std
-{
-
-template<class T>
-class complex
-{
-public:
-    typedef T value_type;
-
-    complex(const T& re = T(), const T& im = T()); // constexpr in C++14
-    complex(const complex&);  // constexpr in C++14
-    template<class X> complex(const complex<X>&);  // constexpr in C++14
-
-    T real() const; // constexpr in C++14
-    T imag() const; // constexpr in C++14
-
-    void real(T);
-    void imag(T);
-
-    complex<T>& operator= (const T&);
-    complex<T>& operator+=(const T&);
-    complex<T>& operator-=(const T&);
-    complex<T>& operator*=(const T&);
-    complex<T>& operator/=(const T&);
-
-    complex& operator=(const complex&);
-    template<class X> complex<T>& operator= (const complex<X>&);
-    template<class X> complex<T>& operator+=(const complex<X>&);
-    template<class X> complex<T>& operator-=(const complex<X>&);
-    template<class X> complex<T>& operator*=(const complex<X>&);
-    template<class X> complex<T>& operator/=(const complex<X>&);
-};
-
-template<>
-class complex<float>
-{
-public:
-    typedef float value_type;
-
-    constexpr complex(float re = 0.0f, float im = 0.0f);
-    explicit constexpr complex(const complex<double>&);
-    explicit constexpr complex(const complex<long double>&);
-
-    constexpr float real() const;
-    void real(float);
-    constexpr float imag() const;
-    void imag(float);
-
-    complex<float>& operator= (float);
-    complex<float>& operator+=(float);
-    complex<float>& operator-=(float);
-    complex<float>& operator*=(float);
-    complex<float>& operator/=(float);
-
-    complex<float>& operator=(const complex<float>&);
-    template<class X> complex<float>& operator= (const complex<X>&);
-    template<class X> complex<float>& operator+=(const complex<X>&);
-    template<class X> complex<float>& operator-=(const complex<X>&);
-    template<class X> complex<float>& operator*=(const complex<X>&);
-    template<class X> complex<float>& operator/=(const complex<X>&);
-};
-
-template<>
-class complex<double>
-{
-public:
-    typedef double value_type;
-
-    constexpr complex(double re = 0.0, double im = 0.0);
-    constexpr complex(const complex<float>&);
-    explicit constexpr complex(const complex<long double>&);
-
-    constexpr double real() const;
-    void real(double);
-    constexpr double imag() const;
-    void imag(double);
-
-    complex<double>& operator= (double);
-    complex<double>& operator+=(double);
-    complex<double>& operator-=(double);
-    complex<double>& operator*=(double);
-    complex<double>& operator/=(double);
-    complex<double>& operator=(const complex<double>&);
-
-    template<class X> complex<double>& operator= (const complex<X>&);
-    template<class X> complex<double>& operator+=(const complex<X>&);
-    template<class X> complex<double>& operator-=(const complex<X>&);
-    template<class X> complex<double>& operator*=(const complex<X>&);
-    template<class X> complex<double>& operator/=(const complex<X>&);
-};
-
-template<>
-class complex<long double>
-{
-public:
-    typedef long double value_type;
-
-    constexpr complex(long double re = 0.0L, long double im = 0.0L);
-    constexpr complex(const complex<float>&);
-    constexpr complex(const complex<double>&);
-
-    constexpr long double real() const;
-    void real(long double);
-    constexpr long double imag() const;
-    void imag(long double);
-
-    complex<long double>& operator=(const complex<long double>&);
-    complex<long double>& operator= (long double);
-    complex<long double>& operator+=(long double);
-    complex<long double>& operator-=(long double);
-    complex<long double>& operator*=(long double);
-    complex<long double>& operator/=(long double);
-
-    template<class X> complex<long double>& operator= (const complex<X>&);
-    template<class X> complex<long double>& operator+=(const complex<X>&);
-    template<class X> complex<long double>& operator-=(const complex<X>&);
-    template<class X> complex<long double>& operator*=(const complex<X>&);
-    template<class X> complex<long double>& operator/=(const complex<X>&);
-};
-
-// 26.3.6 operators:
-template<class T> complex<T> operator+(const complex<T>&, const complex<T>&);
-template<class T> complex<T> operator+(const complex<T>&, const T&);
-template<class T> complex<T> operator+(const T&, const complex<T>&);
-template<class T> complex<T> operator-(const complex<T>&, const complex<T>&);
-template<class T> complex<T> operator-(const complex<T>&, const T&);
-template<class T> complex<T> operator-(const T&, const complex<T>&);
-template<class T> complex<T> operator*(const complex<T>&, const complex<T>&);
-template<class T> complex<T> operator*(const complex<T>&, const T&);
-template<class T> complex<T> operator*(const T&, const complex<T>&);
-template<class T> complex<T> operator/(const complex<T>&, const complex<T>&);
-template<class T> complex<T> operator/(const complex<T>&, const T&);
-template<class T> complex<T> operator/(const T&, const complex<T>&);
-template<class T> complex<T> operator+(const complex<T>&);
-template<class T> complex<T> operator-(const complex<T>&);
-template<class T> bool operator==(const complex<T>&, const complex<T>&); // constexpr in C++14
-template<class T> bool operator==(const complex<T>&, const T&); // constexpr in C++14
-template<class T> bool operator==(const T&, const complex<T>&); // constexpr in C++14
-template<class T> bool operator!=(const complex<T>&, const complex<T>&); // constexpr in C++14
-template<class T> bool operator!=(const complex<T>&, const T&); // constexpr in C++14
-template<class T> bool operator!=(const T&, const complex<T>&); // constexpr in C++14
-
-template<class T, class charT, class traits>
-  basic_istream<charT, traits>&
-  operator>>(basic_istream<charT, traits>&, complex<T>&);
-template<class T, class charT, class traits>
-  basic_ostream<charT, traits>&
-  operator<<(basic_ostream<charT, traits>&, const complex<T>&);
-
-// 26.3.7 values:
-
-template<class T>              T real(const complex<T>&); // constexpr in C++14
-                     long double real(long double);       // constexpr in C++14
-                          double real(double);            // constexpr in C++14
-template<Integral T>      double real(T);                 // constexpr in C++14
-                          float  real(float);             // constexpr in C++14
-
-template<class T>              T imag(const complex<T>&); // constexpr in C++14
-                     long double imag(long double);       // constexpr in C++14
-                          double imag(double);            // constexpr in C++14
-template<Integral T>      double imag(T);                 // constexpr in C++14
-                          float  imag(float);             // constexpr in C++14
-
-template<class T> T abs(const complex<T>&);
-
-template<class T>              T arg(const complex<T>&);
-                     long double arg(long double);
-                          double arg(double);
-template<Integral T>      double arg(T);
-                          float  arg(float);
-
-template<class T>              T norm(const complex<T>&);
-                     long double norm(long double);
-                          double norm(double);
-template<Integral T>      double norm(T);
-                          float  norm(float);
-
-template<class T>      complex<T>           conj(const complex<T>&);
-                       complex<long double> conj(long double);
-                       complex<double>      conj(double);
-template<Integral T>   complex<double>      conj(T);
-                       complex<float>       conj(float);
-
-template<class T>    complex<T>           proj(const complex<T>&);
-                     complex<long double> proj(long double);
-                     complex<double>      proj(double);
-template<Integral T> complex<double>      proj(T);
-                     complex<float>       proj(float);
-
-template<class T> complex<T> polar(const T&, const T& = T());
-
-// 26.3.8 transcendentals:
-template<class T> complex<T> acos(const complex<T>&);
-template<class T> complex<T> asin(const complex<T>&);
-template<class T> complex<T> atan(const complex<T>&);
-template<class T> complex<T> acosh(const complex<T>&);
-template<class T> complex<T> asinh(const complex<T>&);
-template<class T> complex<T> atanh(const complex<T>&);
-template<class T> complex<T> cos (const complex<T>&);
-template<class T> complex<T> cosh (const complex<T>&);
-template<class T> complex<T> exp (const complex<T>&);
-template<class T> complex<T> log (const complex<T>&);
-template<class T> complex<T> log10(const complex<T>&);
-
-template<class T> complex<T> pow(const complex<T>&, const T&);
-template<class T> complex<T> pow(const complex<T>&, const complex<T>&);
-template<class T> complex<T> pow(const T&, const complex<T>&);
-
-template<class T> complex<T> sin (const complex<T>&);
-template<class T> complex<T> sinh (const complex<T>&);
-template<class T> complex<T> sqrt (const complex<T>&);
-template<class T> complex<T> tan (const complex<T>&);
-template<class T> complex<T> tanh (const complex<T>&);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/complex.syn.
 
 #include <__config>
 #include <cmath>
diff --git a/libcxx/include/concepts b/libcxx/include/concepts
--- a/libcxx/include/concepts
+++ b/libcxx/include/concepts
@@ -10,124 +10,7 @@
 #ifndef _LIBCPP_CONCEPTS
 #define _LIBCPP_CONCEPTS
 
-/*
-    concepts synopsis
-namespace std {
-  // [concepts.lang], language-related concepts
-  // [concept.same], concept same_as
-  template<class T, class U>
-    concept same_as = see below;
-
-  // [concept.derived], concept derived_from
-  template<class Derived, class Base>
-    concept derived_from = see below;
-
-  // [concept.convertible], concept convertible_to
-  template<class From, class To>
-    concept convertible_to = see below;
-
-  // [concept.commonref], concept common_reference_with
-  template<class T, class U>
-    concept common_reference_with = see below;
-
-  // [concept.common], concept common_with
-  template<class T, class U>
-    concept common_with = see below;
-
-  // [concepts.arithmetic], arithmetic concepts
-  template<class T>
-    concept integral = see below;
-  template<class T>
-    concept signed_integral = see below;
-  template<class T>
-    concept unsigned_integral = see below;
-  template<class T>
-    concept floating_point = see below;
-
-  // [concept.assignable], concept assignable_from
-  template<class LHS, class RHS>
-    concept assignable_from = see below;
-
-  // [concept.swappable], concept swappable
-  namespace ranges {
-    inline namespace unspecified {
-      inline constexpr unspecified swap = unspecified;
-    }
-  }
-  template<class T>
-    concept swappable = see below;
-  template<class T, class U>
-    concept swappable_with = see below;
-
-  // [concept.destructible], concept destructible
-  template<class T>
-    concept destructible = see below;
-
-  // [concept.constructible], concept constructible_from
-  template<class T, class... Args>
-    concept constructible_from = see below;
-
-  // [concept.default.init], concept default_initializable
-  template<class T>
-    concept default_initializable = see below;
-
-  // [concept.moveconstructible], concept move_constructible
-  template<class T>
-    concept move_constructible = see below;
-
-  // [concept.copyconstructible], concept copy_constructible
-  template<class T>
-    concept copy_constructible = see below;
-
-  // [concept.equalitycomparable], concept equality_comparable
-  template<class T>
-    concept equality_comparable = see below;
-  template<class T, class U>
-    concept equality_comparable_with = see below;
-
-  // [concept.totallyordered], concept totally_ordered
-  template<class T>
-    concept totally_ordered = see below;
-  template<class T, class U>
-    concept totally_ordered_with = see below;
-
-  // [concepts.object], object concepts
-  template<class T>
-    concept movable = see below;
-  template<class T>
-    concept copyable = see below;
-  template<class T>
-    concept semiregular = see below;
-  template<class T>
-    concept regular = see below;
-
-  // [concepts.callable], callable concepts
-  // [concept.invocable], concept invocable
-  template<class F, class... Args>
-    concept invocable = see below;
-
-  // [concept.regularinvocable], concept regular_invocable
-  template<class F, class... Args>
-    concept regular_invocable = see below;
-
-  // [concept.predicate], concept predicate
-  template<class F, class... Args>
-    concept predicate = see below;
-
-  // [concept.relation], concept relation
-  template<class R, class T, class U>
-    concept relation = see below;
-
-  // [concept.equiv], concept equivalence_relation
-  template<class R, class T, class U>
-    concept equivalence_relation = see below;
-
-  // [concept.strictweakorder], concept strict_weak_order
-  template<class R, class T, class U>
-    concept strict_weak_order = see below;
-}
-
-*/
+// Synopsis avaiable at http://wg21.link/concepts.syn.
 
 #include <__config>
 #include <__functional_base>
diff --git a/libcxx/include/condition_variable b/libcxx/include/condition_variable
--- a/libcxx/include/condition_variable
+++ b/libcxx/include/condition_variable
@@ -10,101 +10,7 @@
 #ifndef _LIBCPP_CONDITION_VARIABLE
 #define _LIBCPP_CONDITION_VARIABLE
 
-/*
-    condition_variable synopsis
-
-namespace std
-{
-
-enum class cv_status { no_timeout, timeout };
-
-class condition_variable
-{
-public:
-    condition_variable();
-    ~condition_variable();
-
-    condition_variable(const condition_variable&) = delete;
-    condition_variable& operator=(const condition_variable&) = delete;
-
-    void notify_one() noexcept;
-    void notify_all() noexcept;
-
-    void wait(unique_lock<mutex>& lock);
-    template <class Predicate>
-        void wait(unique_lock<mutex>& lock, Predicate pred);
-
-    template <class Clock, class Duration>
-        cv_status
-        wait_until(unique_lock<mutex>& lock,
-                   const chrono::time_point<Clock, Duration>& abs_time);
-
-    template <class Clock, class Duration, class Predicate>
-        bool
-        wait_until(unique_lock<mutex>& lock,
-                   const chrono::time_point<Clock, Duration>& abs_time,
-                   Predicate pred);
-
-    template <class Rep, class Period>
-        cv_status
-        wait_for(unique_lock<mutex>& lock,
-                 const chrono::duration<Rep, Period>& rel_time);
-
-    template <class Rep, class Period, class Predicate>
-        bool
-        wait_for(unique_lock<mutex>& lock,
-                 const chrono::duration<Rep, Period>& rel_time,
-                 Predicate pred);
-
-    typedef pthread_cond_t* native_handle_type;
-    native_handle_type native_handle();
-};
-
-void notify_all_at_thread_exit(condition_variable& cond, unique_lock<mutex> lk);
-
-class condition_variable_any
-{
-public:
-    condition_variable_any();
-    ~condition_variable_any();
-
-    condition_variable_any(const condition_variable_any&) = delete;
-    condition_variable_any& operator=(const condition_variable_any&) = delete;
-
-    void notify_one() noexcept;
-    void notify_all() noexcept;
-
-    template <class Lock>
-        void wait(Lock& lock);
-    template <class Lock, class Predicate>
-        void wait(Lock& lock, Predicate pred);
-
-    template <class Lock, class Clock, class Duration>
-        cv_status
-        wait_until(Lock& lock,
-                   const chrono::time_point<Clock, Duration>& abs_time);
-
-    template <class Lock, class Clock, class Duration, class Predicate>
-        bool
-        wait_until(Lock& lock,
-                   const chrono::time_point<Clock, Duration>& abs_time,
-                   Predicate pred);
-
-    template <class Lock, class Rep, class Period>
-        cv_status
-        wait_for(Lock& lock,
-                 const chrono::duration<Rep, Period>& rel_time);
-
-    template <class Lock, class Rep, class Period, class Predicate>
-        bool
-        wait_for(Lock& lock,
-                 const chrono::duration<Rep, Period>& rel_time,
-                 Predicate pred);
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/condition.variable.syn.
 
 #include <__config>
 #include <__mutex_base>
diff --git a/libcxx/include/csetjmp b/libcxx/include/csetjmp
--- a/libcxx/include/csetjmp
+++ b/libcxx/include/csetjmp
@@ -10,25 +10,7 @@
 #ifndef _LIBCPP_CSETJMP
 #define _LIBCPP_CSETJMP
 
-/*
-    csetjmp synopsis
-
-Macros:
-
-    setjmp
-
-namespace std
-{
-
-Types:
-
-    jmp_buf
-
-void longjmp(jmp_buf env, int val);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/csetjmp.syn.
 
 #include <__config>
 #include <setjmp.h>
diff --git a/libcxx/include/csignal b/libcxx/include/csignal
--- a/libcxx/include/csignal
+++ b/libcxx/include/csignal
@@ -10,34 +10,7 @@
 #ifndef _LIBCPP_CSIGNAL
 #define _LIBCPP_CSIGNAL
 
-/*
-    csignal synopsis
-
-Macros:
-
-    SIG_DFL
-    SIG_ERR
-    SIG_IGN
-    SIGABRT
-    SIGFPE
-    SIGILL
-    SIGINT
-    SIGSEGV
-    SIGTERM
-
-namespace std
-{
-
-Types:
-
-    sig_atomic_t
-
-void (*signal(int sig, void (*func)(int)))(int);
-int raise(int sig);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/csignal.syn.
 
 #include <__config>
 #include <signal.h>
diff --git a/libcxx/include/cstdarg b/libcxx/include/cstdarg
--- a/libcxx/include/cstdarg
+++ b/libcxx/include/cstdarg
@@ -10,26 +10,7 @@
 #ifndef _LIBCPP_CSTDARG
 #define _LIBCPP_CSTDARG
 
-/*
-    cstdarg synopsis
-
-Macros:
-
-    type va_arg(va_list ap, type);
-    void va_copy(va_list dest, va_list src);  // C99
-    void va_end(va_list ap);
-    void va_start(va_list ap, parmN);
-
-namespace std
-{
-
-Types:
-
-    va_list
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cstdarg.syn.
 
 #include <__config>
 #include <stdarg.h>
diff --git a/libcxx/include/cstddef b/libcxx/include/cstddef
--- a/libcxx/include/cstddef
+++ b/libcxx/include/cstddef
@@ -10,28 +10,7 @@
 #ifndef _LIBCPP_CSTDDEF
 #define _LIBCPP_CSTDDEF
 
-/*
-    cstddef synopsis
-
-Macros:
-
-    offsetof(type,member-designator)
-    NULL
-
-namespace std
-{
-
-Types:
-
-    ptrdiff_t
-    size_t
-    max_align_t // C++11
-    nullptr_t
-    byte // C++17
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cstddef.syn.
 
 #include <__config>
 #include <version>
diff --git a/libcxx/include/cstdint b/libcxx/include/cstdint
--- a/libcxx/include/cstdint
+++ b/libcxx/include/cstdint
@@ -10,135 +10,7 @@
 #ifndef _LIBCPP_CSTDINT
 #define _LIBCPP_CSTDINT
 
-/*
-    cstdint synopsis
-
-Macros:
-
-    INT8_MIN
-    INT16_MIN
-    INT32_MIN
-    INT64_MIN
-
-    INT8_MAX
-    INT16_MAX
-    INT32_MAX
-    INT64_MAX
-
-    UINT8_MAX
-    UINT16_MAX
-    UINT32_MAX
-    UINT64_MAX
-
-    INT_LEAST8_MIN
-    INT_LEAST16_MIN
-    INT_LEAST32_MIN
-    INT_LEAST64_MIN
-
-    INT_LEAST8_MAX
-    INT_LEAST16_MAX
-    INT_LEAST32_MAX
-    INT_LEAST64_MAX
-
-    UINT_LEAST8_MAX
-    UINT_LEAST16_MAX
-    UINT_LEAST32_MAX
-    UINT_LEAST64_MAX
-
-    INT_FAST8_MIN
-    INT_FAST16_MIN
-    INT_FAST32_MIN
-    INT_FAST64_MIN
-
-    INT_FAST8_MAX
-    INT_FAST16_MAX
-    INT_FAST32_MAX
-    INT_FAST64_MAX
-
-    UINT_FAST8_MAX
-    UINT_FAST16_MAX
-    UINT_FAST32_MAX
-    UINT_FAST64_MAX
-
-    INTPTR_MIN
-    INTPTR_MAX
-    UINTPTR_MAX
-
-    INTMAX_MIN
-    INTMAX_MAX
-
-    UINTMAX_MAX
-
-    PTRDIFF_MIN
-    PTRDIFF_MAX
-
-    SIG_ATOMIC_MIN
-    SIG_ATOMIC_MAX
-
-    SIZE_MAX
-
-    WCHAR_MIN
-    WCHAR_MAX
-
-    WINT_MIN
-    WINT_MAX
-
-    INT8_C(value)
-    INT16_C(value)
-    INT32_C(value)
-    INT64_C(value)
-
-    UINT8_C(value)
-    UINT16_C(value)
-    UINT32_C(value)
-    UINT64_C(value)
-
-    INTMAX_C(value)
-    UINTMAX_C(value)
-
-namespace std
-{
-
-Types:
-
-    int8_t
-    int16_t
-    int32_t
-    int64_t
-
-    uint8_t
-    uint16_t
-    uint32_t
-    uint64_t
-
-    int_least8_t
-    int_least16_t
-    int_least32_t
-    int_least64_t
-
-    uint_least8_t
-    uint_least16_t
-    uint_least32_t
-    uint_least64_t
-
-    int_fast8_t
-    int_fast16_t
-    int_fast32_t
-    int_fast64_t
-
-    uint_fast8_t
-    uint_fast16_t
-    uint_fast32_t
-    uint_fast64_t
-
-    intptr_t
-    uintptr_t
-
-    intmax_t
-    uintmax_t
-
-}  // std
-*/
+// Synopsis avaiable at http://wg21.link/cstdint.syn.
 
 #include <__config>
 #include <stdint.h>
diff --git a/libcxx/include/cstdio b/libcxx/include/cstdio
--- a/libcxx/include/cstdio
+++ b/libcxx/include/cstdio
@@ -10,90 +10,7 @@
 #ifndef _LIBCPP_CSTDIO
 #define _LIBCPP_CSTDIO
 
-/*
-    cstdio synopsis
-
-Macros:
-
-    BUFSIZ
-    EOF
-    FILENAME_MAX
-    FOPEN_MAX
-    L_tmpnam
-    NULL
-    SEEK_CUR
-    SEEK_END
-    SEEK_SET
-    TMP_MAX
-    _IOFBF
-    _IOLBF
-    _IONBF
-    stderr
-    stdin
-    stdout
-
-namespace std
-{
-
-Types:
-
-FILE
-fpos_t
-size_t
-
-int remove(const char* filename);
-int rename(const char* old, const char* new);
-FILE* tmpfile(void);
-char* tmpnam(char* s);
-int fclose(FILE* stream);
-int fflush(FILE* stream);
-FILE* fopen(const char* restrict filename, const char* restrict mode);
-FILE* freopen(const char* restrict filename, const char * restrict mode,
-              FILE * restrict stream);
-void setbuf(FILE* restrict stream, char* restrict buf);
-int setvbuf(FILE* restrict stream, char* restrict buf, int mode, size_t size);
-int fprintf(FILE* restrict stream, const char* restrict format, ...);
-int fscanf(FILE* restrict stream, const char * restrict format, ...);
-int printf(const char* restrict format, ...);
-int scanf(const char* restrict format, ...);
-int snprintf(char* restrict s, size_t n, const char* restrict format, ...);    // C99
-int sprintf(char* restrict s, const char* restrict format, ...);
-int sscanf(const char* restrict s, const char* restrict format, ...);
-int vfprintf(FILE* restrict stream, const char* restrict format, va_list arg);
-int vfscanf(FILE* restrict stream, const char* restrict format, va_list arg);  // C99
-int vprintf(const char* restrict format, va_list arg);
-int vscanf(const char* restrict format, va_list arg);                          // C99
-int vsnprintf(char* restrict s, size_t n, const char* restrict format,         // C99
-              va_list arg);
-int vsprintf(char* restrict s, const char* restrict format, va_list arg);
-int vsscanf(const char* restrict s, const char* restrict format, va_list arg); // C99
-int fgetc(FILE* stream);
-char* fgets(char* restrict s, int n, FILE* restrict stream);
-int fputc(int c, FILE* stream);
-int fputs(const char* restrict s, FILE* restrict stream);
-int getc(FILE* stream);
-int getchar(void);
-char* gets(char* s);  // removed in C++14
-int putc(int c, FILE* stream);
-int putchar(int c);
-int puts(const char* s);
-int ungetc(int c, FILE* stream);
-size_t fread(void* restrict ptr, size_t size, size_t nmemb,
-             FILE* restrict stream);
-size_t fwrite(const void* restrict ptr, size_t size, size_t nmemb,
-              FILE* restrict stream);
-int fgetpos(FILE* restrict stream, fpos_t* restrict pos);
-int fseek(FILE* stream, long offset, int whence);
-int fsetpos(FILE*stream, const fpos_t* pos);
-long ftell(FILE* stream);
-void rewind(FILE* stream);
-void clearerr(FILE* stream);
-int feof(FILE* stream);
-int ferror(FILE* stream);
-void perror(const char* s);
-
-}  // std
-*/
+// Synopsis avaiable at http://wg21.link/cstdio.syn.
 
 #include <__config>
 #include <stdio.h>
diff --git a/libcxx/include/cstdlib b/libcxx/include/cstdlib
--- a/libcxx/include/cstdlib
+++ b/libcxx/include/cstdlib
@@ -10,76 +10,7 @@
 #ifndef _LIBCPP_CSTDLIB
 #define _LIBCPP_CSTDLIB
 
-/*
-    cstdlib synopsis
-
-Macros:
-
-    EXIT_FAILURE
-    EXIT_SUCCESS
-    MB_CUR_MAX
-    NULL
-    RAND_MAX
-
-namespace std
-{
-
-Types:
-
-    size_t
-    div_t
-    ldiv_t
-    lldiv_t                                                               // C99
-
-double    atof (const char* nptr);
-int       atoi (const char* nptr);
-long      atol (const char* nptr);
-long long atoll(const char* nptr);                                        // C99
-double             strtod  (const char* restrict nptr, char** restrict endptr);
-float              strtof  (const char* restrict nptr, char** restrict endptr); // C99
-long double        strtold (const char* restrict nptr, char** restrict endptr); // C99
-long               strtol  (const char* restrict nptr, char** restrict endptr, int base);
-long long          strtoll (const char* restrict nptr, char** restrict endptr, int base); // C99
-unsigned long      strtoul (const char* restrict nptr, char** restrict endptr, int base);
-unsigned long long strtoull(const char* restrict nptr, char** restrict endptr, int base); // C99
-int rand(void);
-void srand(unsigned int seed);
-void* calloc(size_t nmemb, size_t size);
-void free(void* ptr);
-void* malloc(size_t size);
-void* realloc(void* ptr, size_t size);
-void abort(void);
-int atexit(void (*func)(void));
-void exit(int status);
-void _Exit(int status);
-char* getenv(const char* name);
-int system(const char* string);
-void* bsearch(const void* key, const void* base, size_t nmemb, size_t size,
-              int (*compar)(const void *, const void *));
-void qsort(void* base, size_t nmemb, size_t size,
-           int (*compar)(const void *, const void *));
-int         abs(      int j);
-long        abs(     long j);
-long long   abs(long long j);                                             // C++0X
-long       labs(     long j);
-long long llabs(long long j);                                             // C99
-div_t     div(      int numer,       int denom);
-ldiv_t    div(     long numer,      long denom);
-lldiv_t   div(long long numer, long long denom);                          // C++0X
-ldiv_t   ldiv(     long numer,      long denom);
-lldiv_t lldiv(long long numer, long long denom);                          // C99
-int mblen(const char* s, size_t n);
-int mbtowc(wchar_t* restrict pwc, const char* restrict s, size_t n);
-int wctomb(char* s, wchar_t wchar);
-size_t mbstowcs(wchar_t* restrict pwcs, const char* restrict s, size_t n);
-size_t wcstombs(char* restrict s, const wchar_t* restrict pwcs, size_t n);
-int at_quick_exit(void (*func)(void))                                     // C++11
-void quick_exit(int status);                                              // C++11
-void *aligned_alloc(size_t alignment, size_t size);                       // C11
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cstdlib.syn.
 
 #include <__config>
 #include <stdlib.h>
diff --git a/libcxx/include/cstring b/libcxx/include/cstring
--- a/libcxx/include/cstring
+++ b/libcxx/include/cstring
@@ -10,51 +10,7 @@
 #ifndef _LIBCPP_CSTRING
 #define _LIBCPP_CSTRING
 
-/*
-    cstring synopsis
-
-Macros:
-
-    NULL
-
-namespace std
-{
-
-Types:
-
-    size_t
-
-void* memcpy(void* restrict s1, const void* restrict s2, size_t n);
-void* memmove(void* s1, const void* s2, size_t n);
-char* strcpy (char* restrict s1, const char* restrict s2);
-char* strncpy(char* restrict s1, const char* restrict s2, size_t n);
-char* strcat (char* restrict s1, const char* restrict s2);
-char* strncat(char* restrict s1, const char* restrict s2, size_t n);
-int memcmp(const void* s1, const void* s2, size_t n);
-int strcmp (const char* s1, const char* s2);
-int strncmp(const char* s1, const char* s2, size_t n);
-int strcoll(const char* s1, const char* s2);
-size_t strxfrm(char* restrict s1, const char* restrict s2, size_t n);
-const void* memchr(const void* s, int c, size_t n);
-      void* memchr(      void* s, int c, size_t n);
-const char* strchr(const char* s, int c);
-      char* strchr(      char* s, int c);
-size_t strcspn(const char* s1, const char* s2);
-const char* strpbrk(const char* s1, const char* s2);
-      char* strpbrk(      char* s1, const char* s2);
-const char* strrchr(const char* s, int c);
-      char* strrchr(      char* s, int c);
-size_t strspn(const char* s1, const char* s2);
-const char* strstr(const char* s1, const char* s2);
-      char* strstr(      char* s1, const char* s2);
-char* strtok(char* restrict s1, const char* restrict s2);
-void* memset(void* s, int c, size_t n);
-char* strerror(int errnum);
-size_t strlen(const char* s);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cstring.syn.
 
 #include <__config>
 #include <string.h>
diff --git a/libcxx/include/ctime b/libcxx/include/ctime
--- a/libcxx/include/ctime
+++ b/libcxx/include/ctime
@@ -10,40 +10,7 @@
 #ifndef _LIBCPP_CTIME
 #define _LIBCPP_CTIME
 
-/*
-    ctime synopsis
-
-Macros:
-
-    NULL
-    CLOCKS_PER_SEC
-    TIME_UTC // C++17
-
-namespace std
-{
-
-Types:
-
-    clock_t
-    size_t
-    time_t
-    tm
-    timespec // C++17
-
-clock_t clock();
-double difftime(time_t time1, time_t time0);
-time_t mktime(tm* timeptr);
-time_t time(time_t* timer);
-char* asctime(const tm* timeptr);
-char* ctime(const time_t* timer);
-tm*    gmtime(const time_t* timer);
-tm* localtime(const time_t* timer);
-size_t strftime(char* restrict s, size_t maxsize, const char* restrict format,
-                const tm* restrict timeptr);
-int timespec_get( struct timespec *ts, int base); // C++17
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/ctime.syn.
 
 #include <__config>
 #include <time.h>
diff --git a/libcxx/include/cwchar b/libcxx/include/cwchar
--- a/libcxx/include/cwchar
+++ b/libcxx/include/cwchar
@@ -10,97 +10,7 @@
 #ifndef _LIBCPP_CWCHAR
 #define _LIBCPP_CWCHAR
 
-/*
-    cwchar synopsis
-
-Macros:
-
-    NULL
-    WCHAR_MAX
-    WCHAR_MIN
-    WEOF
-
-namespace std
-{
-
-Types:
-
-    mbstate_t
-    size_t
-    tm
-    wint_t
-
-int fwprintf(FILE* restrict stream, const wchar_t* restrict format, ...);
-int fwscanf(FILE* restrict stream, const wchar_t* restrict format, ...);
-int swprintf(wchar_t* restrict s, size_t n, const wchar_t* restrict format, ...);
-int swscanf(const wchar_t* restrict s, const wchar_t* restrict format, ...);
-int vfwprintf(FILE* restrict stream, const wchar_t* restrict format, va_list arg);
-int vfwscanf(FILE* restrict stream, const wchar_t* restrict format, va_list arg);  // C99
-int vswprintf(wchar_t* restrict s, size_t n, const wchar_t* restrict format, va_list arg);
-int vswscanf(const wchar_t* restrict s, const wchar_t* restrict format, va_list arg);  // C99
-int vwprintf(const wchar_t* restrict format, va_list arg);
-int vwscanf(const wchar_t* restrict format, va_list arg);  // C99
-int wprintf(const wchar_t* restrict format, ...);
-int wscanf(const wchar_t* restrict format, ...);
-wint_t fgetwc(FILE* stream);
-wchar_t* fgetws(wchar_t* restrict s, int n, FILE* restrict stream);
-wint_t fputwc(wchar_t c, FILE* stream);
-int fputws(const wchar_t* restrict s, FILE* restrict stream);
-int fwide(FILE* stream, int mode);
-wint_t getwc(FILE* stream);
-wint_t getwchar();
-wint_t putwc(wchar_t c, FILE* stream);
-wint_t putwchar(wchar_t c);
-wint_t ungetwc(wint_t c, FILE* stream);
-double wcstod(const wchar_t* restrict nptr, wchar_t** restrict endptr);
-float wcstof(const wchar_t* restrict nptr, wchar_t** restrict endptr);         // C99
-long double wcstold(const wchar_t* restrict nptr, wchar_t** restrict endptr);  // C99
-long wcstol(const wchar_t* restrict nptr, wchar_t** restrict endptr, int base);
-long long wcstoll(const wchar_t* restrict nptr, wchar_t** restrict endptr, int base);  // C99
-unsigned long wcstoul(const wchar_t* restrict nptr, wchar_t** restrict endptr, int base);
-unsigned long long wcstoull(const wchar_t* restrict nptr, wchar_t** restrict endptr, int base);  // C99
-wchar_t* wcscpy(wchar_t* restrict s1, const wchar_t* restrict s2);
-wchar_t* wcsncpy(wchar_t* restrict s1, const wchar_t* restrict s2, size_t n);
-wchar_t* wcscat(wchar_t* restrict s1, const wchar_t* restrict s2);
-wchar_t* wcsncat(wchar_t* restrict s1, const wchar_t* restrict s2, size_t n);
-int wcscmp(const wchar_t* s1, const wchar_t* s2);
-int wcscoll(const wchar_t* s1, const wchar_t* s2);
-int wcsncmp(const wchar_t* s1, const wchar_t* s2, size_t n);
-size_t wcsxfrm(wchar_t* restrict s1, const wchar_t* restrict s2, size_t n);
-const wchar_t* wcschr(const wchar_t* s, wchar_t c);
-      wchar_t* wcschr(      wchar_t* s, wchar_t c);
-size_t wcscspn(const wchar_t* s1, const wchar_t* s2);
-size_t wcslen(const wchar_t* s);
-const wchar_t* wcspbrk(const wchar_t* s1, const wchar_t* s2);
-      wchar_t* wcspbrk(      wchar_t* s1, const wchar_t* s2);
-const wchar_t* wcsrchr(const wchar_t* s, wchar_t c);
-      wchar_t* wcsrchr(      wchar_t* s, wchar_t c);
-size_t wcsspn(const wchar_t* s1, const wchar_t* s2);
-const wchar_t* wcsstr(const wchar_t* s1, const wchar_t* s2);
-      wchar_t* wcsstr(      wchar_t* s1, const wchar_t* s2);
-wchar_t* wcstok(wchar_t* restrict s1, const wchar_t* restrict s2, wchar_t** restrict ptr);
-const wchar_t* wmemchr(const wchar_t* s, wchar_t c, size_t n);
-      wchar_t* wmemchr(      wchar_t* s, wchar_t c, size_t n);
-int wmemcmp(wchar_t* restrict s1, const wchar_t* restrict s2, size_t n);
-wchar_t* wmemcpy(wchar_t* restrict s1, const wchar_t* restrict s2, size_t n);
-wchar_t* wmemmove(wchar_t* s1, const wchar_t* s2, size_t n);
-wchar_t* wmemset(wchar_t* s, wchar_t c, size_t n);
-size_t wcsftime(wchar_t* restrict s, size_t maxsize, const wchar_t* restrict format,
-                const tm* restrict timeptr);
-wint_t btowc(int c);
-int wctob(wint_t c);
-int mbsinit(const mbstate_t* ps);
-size_t mbrlen(const char* restrict s, size_t n, mbstate_t* restrict ps);
-size_t mbrtowc(wchar_t* restrict pwc, const char* restrict s, size_t n, mbstate_t* restrict ps);
-size_t wcrtomb(char* restrict s, wchar_t wc, mbstate_t* restrict ps);
-size_t mbsrtowcs(wchar_t* restrict dst, const char** restrict src, size_t len,
-                 mbstate_t* restrict ps);
-size_t wcsrtombs(char* restrict dst, const wchar_t** restrict src, size_t len,
-                 mbstate_t* restrict ps);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cwchar.syn.
 
 #include <__config>
 #include <cwctype>
diff --git a/libcxx/include/cwctype b/libcxx/include/cwctype
--- a/libcxx/include/cwctype
+++ b/libcxx/include/cwctype
@@ -10,44 +10,7 @@
 #ifndef _LIBCPP_CWCTYPE
 #define _LIBCPP_CWCTYPE
 
-/*
-    cwctype synopsis
-
-Macros:
-
-    WEOF
-
-namespace std
-{
-
-Types:
-
-    wint_t
-    wctrans_t
-    wctype_t
-
-int iswalnum(wint_t wc);
-int iswalpha(wint_t wc);
-int iswblank(wint_t wc);  // C99
-int iswcntrl(wint_t wc);
-int iswdigit(wint_t wc);
-int iswgraph(wint_t wc);
-int iswlower(wint_t wc);
-int iswprint(wint_t wc);
-int iswpunct(wint_t wc);
-int iswspace(wint_t wc);
-int iswupper(wint_t wc);
-int iswxdigit(wint_t wc);
-int iswctype(wint_t wc, wctype_t desc);
-wctype_t wctype(const char* property);
-wint_t towlower(wint_t wc);
-wint_t towupper(wint_t wc);
-wint_t towctrans(wint_t wc, wctrans_t desc);
-wctrans_t wctrans(const char* property);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/cwtype.syn.
 
 #include <__config>
 #include <cctype>
diff --git a/libcxx/include/deque b/libcxx/include/deque
--- a/libcxx/include/deque
+++ b/libcxx/include/deque
@@ -10,155 +10,7 @@
 #ifndef _LIBCPP_DEQUE
 #define _LIBCPP_DEQUE
 
-/*
-    deque synopsis
-
-namespace std
-{
-
-template <class T, class Allocator = allocator<T> >
-class deque
-{
-public:
-    // types:
-    typedef T value_type;
-    typedef Allocator allocator_type;
-
-    typedef typename allocator_type::reference       reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-
-    typedef typename allocator_type::pointer         pointer;
-    typedef typename allocator_type::const_pointer   const_pointer;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-
-    // construct/copy/destroy:
-    deque() noexcept(is_nothrow_default_constructible<allocator_type>::value);
-    explicit deque(const allocator_type& a);
-    explicit deque(size_type n);
-    explicit deque(size_type n, const allocator_type& a); // C++14
-    deque(size_type n, const value_type& v);
-    deque(size_type n, const value_type& v, const allocator_type& a);
-    template <class InputIterator>
-        deque(InputIterator f, InputIterator l);
-    template <class InputIterator>
-        deque(InputIterator f, InputIterator l, const allocator_type& a);
-    deque(const deque& c);
-    deque(deque&& c)
-        noexcept(is_nothrow_move_constructible<allocator_type>::value);
-    deque(initializer_list<value_type> il, const Allocator& a = allocator_type());
-    deque(const deque& c, const allocator_type& a);
-    deque(deque&& c, const allocator_type& a);
-    ~deque();
-
-    deque& operator=(const deque& c);
-    deque& operator=(deque&& c)
-        noexcept(
-             allocator_type::propagate_on_container_move_assignment::value &&
-             is_nothrow_move_assignable<allocator_type>::value);
-    deque& operator=(initializer_list<value_type> il);
-
-    template <class InputIterator>
-        void assign(InputIterator f, InputIterator l);
-    void assign(size_type n, const value_type& v);
-    void assign(initializer_list<value_type> il);
-
-    allocator_type get_allocator() const noexcept;
-
-    // iterators:
-
-    iterator       begin() noexcept;
-    const_iterator begin() const noexcept;
-    iterator       end() noexcept;
-    const_iterator end() const noexcept;
-
-    reverse_iterator       rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-    reverse_iterator       rend() noexcept;
-    const_reverse_iterator rend() const noexcept;
-
-    const_iterator         cbegin() const noexcept;
-    const_iterator         cend() const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend() const noexcept;
-
-    // capacity:
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-    void resize(size_type n);
-    void resize(size_type n, const value_type& v);
-    void shrink_to_fit();
-    bool empty() const noexcept;
-
-    // element access:
-    reference operator[](size_type i);
-    const_reference operator[](size_type i) const;
-    reference at(size_type i);
-    const_reference at(size_type i) const;
-    reference front();
-    const_reference front() const;
-    reference back();
-    const_reference back() const;
-
-    // modifiers:
-    void push_front(const value_type& v);
-    void push_front(value_type&& v);
-    void push_back(const value_type& v);
-    void push_back(value_type&& v);
-    template <class... Args> reference emplace_front(Args&&... args);  // reference in C++17
-    template <class... Args> reference emplace_back(Args&&... args);   // reference in C++17
-    template <class... Args> iterator emplace(const_iterator p, Args&&... args);
-    iterator insert(const_iterator p, const value_type& v);
-    iterator insert(const_iterator p, value_type&& v);
-    iterator insert(const_iterator p, size_type n, const value_type& v);
-    template <class InputIterator>
-        iterator insert(const_iterator p, InputIterator f, InputIterator l);
-    iterator insert(const_iterator p, initializer_list<value_type> il);
-    void pop_front();
-    void pop_back();
-    iterator erase(const_iterator p);
-    iterator erase(const_iterator f, const_iterator l);
-    void swap(deque& c)
-        noexcept(allocator_traits<allocator_type>::is_always_equal::value);  // C++17
-    void clear() noexcept;
-};
-
-template <class InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-   deque(InputIterator, InputIterator, Allocator = Allocator())
-   -> deque<typename iterator_traits<InputIterator>::value_type, Allocator>;
-
-template <class T, class Allocator>
-    bool operator==(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
-template <class T, class Allocator>
-    bool operator< (const deque<T,Allocator>& x, const deque<T,Allocator>& y);
-template <class T, class Allocator>
-    bool operator!=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
-template <class T, class Allocator>
-    bool operator> (const deque<T,Allocator>& x, const deque<T,Allocator>& y);
-template <class T, class Allocator>
-    bool operator>=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
-template <class T, class Allocator>
-    bool operator<=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
-
-// specialized algorithms:
-template <class T, class Allocator>
-    void swap(deque<T,Allocator>& x, deque<T,Allocator>& y)
-         noexcept(noexcept(x.swap(y)));
-
-template <class T, class Allocator, class U>
-    typename deque<T, Allocator>::size_type
-    erase(deque<T, Allocator>& c, const U& value);       // C++20
-template <class T, class Allocator, class Predicate>
-    typename deque<T, Allocator>::size_type
-    erase_if(deque<T, Allocator>& c, Predicate pred);    // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/deque.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/exception b/libcxx/include/exception
--- a/libcxx/include/exception
+++ b/libcxx/include/exception
@@ -10,71 +10,7 @@
 #ifndef _LIBCPP_EXCEPTION
 #define _LIBCPP_EXCEPTION
 
-/*
-    exception synopsis
-
-namespace std
-{
-
-class exception
-{
-public:
-    exception() noexcept;
-    exception(const exception&) noexcept;
-    exception& operator=(const exception&) noexcept;
-    virtual ~exception() noexcept;
-    virtual const char* what() const noexcept;
-};
-
-class bad_exception
-    : public exception
-{
-public:
-    bad_exception() noexcept;
-    bad_exception(const bad_exception&) noexcept;
-    bad_exception& operator=(const bad_exception&) noexcept;
-    virtual ~bad_exception() noexcept;
-    virtual const char* what() const noexcept;
-};
-
-typedef void (*unexpected_handler)();
-unexpected_handler set_unexpected(unexpected_handler  f ) noexcept;
-unexpected_handler get_unexpected() noexcept;
-[[noreturn]] void unexpected();
-
-typedef void (*terminate_handler)();
-terminate_handler set_terminate(terminate_handler  f ) noexcept;
-terminate_handler get_terminate() noexcept;
-[[noreturn]] void terminate() noexcept;
-
-bool uncaught_exception()  noexcept;
-int  uncaught_exceptions() noexcept;  // C++17
-
-typedef unspecified exception_ptr;
-
-exception_ptr current_exception() noexcept;
-void rethrow_exception [[noreturn]] (exception_ptr p);
-template<class E> exception_ptr make_exception_ptr(E e) noexcept;
-
-class nested_exception
-{
-public:
-    nested_exception() noexcept;
-    nested_exception(const nested_exception&) noexcept = default;
-    nested_exception& operator=(const nested_exception&) noexcept = default;
-    virtual ~nested_exception() = default;
-
-    // access functions
-    [[noreturn]] void rethrow_nested() const;
-    exception_ptr nested_ptr() const noexcept;
-};
-
-template <class T> [[noreturn]] void throw_with_nested(T&& t);
-template <class E> void rethrow_if_nested(const E& e);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/exception.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/filesystem b/libcxx/include/filesystem
--- a/libcxx/include/filesystem
+++ b/libcxx/include/filesystem
@@ -8,226 +8,8 @@
 //===----------------------------------------------------------------------===//
 #ifndef _LIBCPP_FILESYSTEM
 #define _LIBCPP_FILESYSTEM
-/*
-    filesystem synopsis
 
-    namespace std { namespace filesystem {
-
-    class path;
-
-    void swap(path& lhs, path& rhs) noexcept;
-    size_t hash_value(const path& p) noexcept;
-
-    bool operator==(const path& lhs, const path& rhs) noexcept;
-    bool operator!=(const path& lhs, const path& rhs) noexcept;
-    bool operator< (const path& lhs, const path& rhs) noexcept;
-    bool operator<=(const path& lhs, const path& rhs) noexcept;
-    bool operator> (const path& lhs, const path& rhs) noexcept;
-    bool operator>=(const path& lhs, const path& rhs) noexcept;
-
-    path operator/ (const path& lhs, const path& rhs);
-
-    // fs.path.io operators are friends of path.
-    template <class charT, class traits>
-    friend basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os, const path& p);
-
-    template <class charT, class traits>
-    friend basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is, path& p);
-
-    template <class Source>
-      path u8path(const Source& source);
-    template <class InputIterator>
-      path u8path(InputIterator first, InputIterator last);
-
-    class filesystem_error;
-    class directory_entry;
-
-    class directory_iterator;
-
-    // enable directory_iterator range-based for statements
-    directory_iterator begin(directory_iterator iter) noexcept;
-    directory_iterator end(const directory_iterator&) noexcept;
-
-    class recursive_directory_iterator;
-
-    // enable recursive_directory_iterator range-based for statements
-    recursive_directory_iterator begin(recursive_directory_iterator iter) noexcept;
-    recursive_directory_iterator end(const recursive_directory_iterator&) noexcept;
-
-    class file_status;
-
-    struct space_info
-    {
-      uintmax_t capacity;
-      uintmax_t free;
-      uintmax_t available;
-    };
-
-    enum class file_type;
-    enum class perms;
-    enum class perm_options;
-    enum class copy_options;
-    enum class directory_options;
-
-    typedef chrono::time_point<trivial-clock>  file_time_type;
-
-    // operational functions
-
-    path absolute(const path& p);
-    path absolute(const path& p, error_code &ec);
-
-    path canonical(const path& p);
-    path canonical(const path& p, error_code& ec);
-
-    void copy(const path& from, const path& to);
-    void copy(const path& from, const path& to, error_code& ec);
-    void copy(const path& from, const path& to, copy_options options);
-    void copy(const path& from, const path& to, copy_options options,
-                   error_code& ec);
-
-    bool copy_file(const path& from, const path& to);
-    bool copy_file(const path& from, const path& to, error_code& ec);
-    bool copy_file(const path& from, const path& to, copy_options option);
-    bool copy_file(const path& from, const path& to, copy_options option,
-                           error_code& ec);
-
-    void copy_symlink(const path& existing_symlink, const path& new_symlink);
-    void copy_symlink(const path& existing_symlink, const path& new_symlink,
-                              error_code& ec) noexcept;
-
-    bool create_directories(const path& p);
-    bool create_directories(const path& p, error_code& ec);
-
-    bool create_directory(const path& p);
-    bool create_directory(const path& p, error_code& ec) noexcept;
-
-    bool create_directory(const path& p, const path& attributes);
-    bool create_directory(const path& p, const path& attributes,
-                                  error_code& ec) noexcept;
-
-    void create_directory_symlink(const path& to, const path& new_symlink);
-    void create_directory_symlink(const path& to, const path& new_symlink,
-                                          error_code& ec) noexcept;
-
-    void create_hard_link(const path& to, const path& new_hard_link);
-    void create_hard_link(const path& to, const path& new_hard_link,
-                                  error_code& ec) noexcept;
-
-    void create_symlink(const path& to, const path& new_symlink);
-    void create_symlink(const path& to, const path& new_symlink,
-                                error_code& ec) noexcept;
-
-    path current_path();
-    path current_path(error_code& ec);
-    void current_path(const path& p);
-    void current_path(const path& p, error_code& ec) noexcept;
-
-    bool exists(file_status s) noexcept;
-    bool exists(const path& p);
-    bool exists(const path& p, error_code& ec) noexcept;
-
-    bool equivalent(const path& p1, const path& p2);
-    bool equivalent(const path& p1, const path& p2, error_code& ec) noexcept;
-
-    uintmax_t    file_size(const path& p);
-    uintmax_t    file_size(const path& p, error_code& ec) noexcept;
-
-    uintmax_t    hard_link_count(const path& p);
-    uintmax_t    hard_link_count(const path& p, error_code& ec) noexcept;
-
-    bool is_block_file(file_status s) noexcept;
-    bool is_block_file(const path& p);
-    bool is_block_file(const path& p, error_code& ec) noexcept;
-
-    bool is_character_file(file_status s) noexcept;
-    bool is_character_file(const path& p);
-    bool is_character_file(const path& p, error_code& ec) noexcept;
-
-    bool is_directory(file_status s) noexcept;
-    bool is_directory(const path& p);
-    bool is_directory(const path& p, error_code& ec) noexcept;
-
-    bool is_empty(const path& p);
-    bool is_empty(const path& p, error_code& ec) noexcept;
-
-    bool is_fifo(file_status s) noexcept;
-    bool is_fifo(const path& p);
-    bool is_fifo(const path& p, error_code& ec) noexcept;
-
-    bool is_other(file_status s) noexcept;
-    bool is_other(const path& p);
-    bool is_other(const path& p, error_code& ec) noexcept;
-
-    bool is_regular_file(file_status s) noexcept;
-    bool is_regular_file(const path& p);
-    bool is_regular_file(const path& p, error_code& ec) noexcept;
-
-    bool is_socket(file_status s) noexcept;
-    bool is_socket(const path& p);
-    bool is_socket(const path& p, error_code& ec) noexcept;
-
-    bool is_symlink(file_status s) noexcept;
-    bool is_symlink(const path& p);
-    bool is_symlink(const path& p, error_code& ec) noexcept;
-
-    file_time_type  last_write_time(const path& p);
-    file_time_type  last_write_time(const path& p, error_code& ec) noexcept;
-    void last_write_time(const path& p, file_time_type new_time);
-    void last_write_time(const path& p, file_time_type new_time,
-                                 error_code& ec) noexcept;
-
-    void permissions(const path& p, perms prms,
-                     perm_options opts=perm_options::replace);
-    void permissions(const path& p, perms prms, error_code& ec) noexcept;
-    void permissions(const path& p, perms prms, perm_options opts,
-                     error_code& ec);
-
-    path proximate(const path& p, error_code& ec);
-    path proximate(const path& p, const path& base = current_path());
-    path proximate(const path& p, const path& base, error_code &ec);
-
-    path read_symlink(const path& p);
-    path read_symlink(const path& p, error_code& ec);
-
-    path relative(const path& p, error_code& ec);
-    path relative(const path& p, const path& base=current_path());
-    path relative(const path& p, const path& base, error_code& ec);
-
-    bool remove(const path& p);
-    bool remove(const path& p, error_code& ec) noexcept;
-
-    uintmax_t    remove_all(const path& p);
-    uintmax_t    remove_all(const path& p, error_code& ec);
-
-    void rename(const path& from, const path& to);
-    void rename(const path& from, const path& to, error_code& ec) noexcept;
-
-    void resize_file(const path& p, uintmax_t size);
-    void resize_file(const path& p, uintmax_t size, error_code& ec) noexcept;
-
-    space_info   space(const path& p);
-    space_info   space(const path& p, error_code& ec) noexcept;
-
-    file_status  status(const path& p);
-    file_status  status(const path& p, error_code& ec) noexcept;
-
-    bool status_known(file_status s) noexcept;
-
-    file_status  symlink_status(const path& p);
-    file_status  symlink_status(const path& p, error_code& ec) noexcept;
-
-    path temp_directory_path();
-    path temp_directory_path(error_code& ec);
-
-    path weakly_canonical(path const& p);
-    path weakly_canonical(path const& p, error_code& ec);
-
-
-} }  // namespaces std::filesystem
-
-*/
+// Synopsis avaiable at http://wg21.link/fs.filesystem.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/format b/libcxx/include/format
--- a/libcxx/include/format
+++ b/libcxx/include/format
@@ -10,50 +10,7 @@
 #ifndef _LIBCPP_FORMAT
 #define _LIBCPP_FORMAT
 
-/*
-
-namespace std {
-  // [format.error], class format_error
-  class format_error : public runtime_error {
-  public:
-    explicit format_error(const string& what_arg);
-    explicit format_error(const char* what_arg);
-  };
-
-  // [format.parse.ctx], class template basic_format_parse_context
-  template<class charT>
-  class basic_format_parse_context {
-  public:
-    using char_type = charT;
-    using const_iterator = typename basic_string_view<charT>::const_iterator;
-    using iterator = const_iterator;
-
-  private:
-    iterator begin_;                                    // exposition only
-    iterator end_;                                      // exposition only
-    enum indexing { unknown, manual, automatic };       // exposition only
-    indexing indexing_;                                 // exposition only
-    size_t next_arg_id_;                                // exposition only
-    size_t num_args_;                                   // exposition only
-
-  public:
-    constexpr explicit basic_format_parse_context(basic_string_view<charT> fmt,
-                                                  size_t num_args = 0) noexcept;
-    basic_format_parse_context(const basic_format_parse_context&) = delete;
-    basic_format_parse_context& operator=(const basic_format_parse_context&) = delete;
-
-    constexpr const_iterator begin() const noexcept;
-    constexpr const_iterator end() const noexcept;
-    constexpr void advance_to(const_iterator it);
-
-    constexpr size_t next_arg_id();
-    constexpr void check_arg_id(size_t id);
-  };
-  using format_parse_context = basic_format_parse_context<char>;
-  using wformat_parse_context = basic_format_parse_context<wchar_t>;
-}
-
-*/
+// Synopsis avaiable at http://wg21.link/format.syn.
 
 #include <__config>
 #include <__format/format_error.h>
diff --git a/libcxx/include/forward_list b/libcxx/include/forward_list
--- a/libcxx/include/forward_list
+++ b/libcxx/include/forward_list
@@ -10,174 +10,7 @@
 #ifndef _LIBCPP_FORWARD_LIST
 #define _LIBCPP_FORWARD_LIST
 
-/*
-    forward_list synopsis
-
-namespace std
-{
-
-template <class T, class Allocator = allocator<T>>
-class forward_list
-{
-public:
-    typedef T         value_type;
-    typedef Allocator allocator_type;
-
-    typedef value_type&                                                reference;
-    typedef const value_type&                                          const_reference;
-    typedef typename allocator_traits<allocator_type>::pointer         pointer;
-    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
-    typedef typename allocator_traits<allocator_type>::size_type       size_type;
-    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
-
-    typedef <details> iterator;
-    typedef <details> const_iterator;
-
-    forward_list()
-        noexcept(is_nothrow_default_constructible<allocator_type>::value);
-    explicit forward_list(const allocator_type& a);
-    explicit forward_list(size_type n);
-    explicit forward_list(size_type n, const allocator_type& a); // C++14
-    forward_list(size_type n, const value_type& v);
-    forward_list(size_type n, const value_type& v, const allocator_type& a);
-    template <class InputIterator>
-        forward_list(InputIterator first, InputIterator last);
-    template <class InputIterator>
-        forward_list(InputIterator first, InputIterator last, const allocator_type& a);
-    forward_list(const forward_list& x);
-    forward_list(const forward_list& x, const allocator_type& a);
-    forward_list(forward_list&& x)
-        noexcept(is_nothrow_move_constructible<allocator_type>::value);
-    forward_list(forward_list&& x, const allocator_type& a);
-    forward_list(initializer_list<value_type> il);
-    forward_list(initializer_list<value_type> il, const allocator_type& a);
-
-    ~forward_list();
-
-    forward_list& operator=(const forward_list& x);
-    forward_list& operator=(forward_list&& x)
-        noexcept(
-             allocator_type::propagate_on_container_move_assignment::value &&
-             is_nothrow_move_assignable<allocator_type>::value);
-    forward_list& operator=(initializer_list<value_type> il);
-
-    template <class InputIterator>
-        void assign(InputIterator first, InputIterator last);
-    void assign(size_type n, const value_type& v);
-    void assign(initializer_list<value_type> il);
-
-    allocator_type get_allocator() const noexcept;
-
-    iterator       begin() noexcept;
-    const_iterator begin() const noexcept;
-    iterator       end() noexcept;
-    const_iterator end() const noexcept;
-
-    const_iterator cbegin() const noexcept;
-    const_iterator cend() const noexcept;
-
-    iterator       before_begin() noexcept;
-    const_iterator before_begin() const noexcept;
-    const_iterator cbefore_begin() const noexcept;
-
-    bool empty() const noexcept;
-    size_type max_size() const noexcept;
-
-    reference       front();
-    const_reference front() const;
-
-    template <class... Args> reference emplace_front(Args&&... args);  // reference in C++17
-    void push_front(const value_type& v);
-    void push_front(value_type&& v);
-
-    void pop_front();
-
-    template <class... Args>
-        iterator emplace_after(const_iterator p, Args&&... args);
-    iterator insert_after(const_iterator p, const value_type& v);
-    iterator insert_after(const_iterator p, value_type&& v);
-    iterator insert_after(const_iterator p, size_type n, const value_type& v);
-    template <class InputIterator>
-        iterator insert_after(const_iterator p,
-                              InputIterator first, InputIterator last);
-    iterator insert_after(const_iterator p, initializer_list<value_type> il);
-
-    iterator erase_after(const_iterator p);
-    iterator erase_after(const_iterator first, const_iterator last);
-
-    void swap(forward_list& x)
-        noexcept(allocator_traits<allocator_type>::is_always_equal::value);  // C++17
-
-    void resize(size_type n);
-    void resize(size_type n, const value_type& v);
-    void clear() noexcept;
-
-    void splice_after(const_iterator p, forward_list& x);
-    void splice_after(const_iterator p, forward_list&& x);
-    void splice_after(const_iterator p, forward_list& x, const_iterator i);
-    void splice_after(const_iterator p, forward_list&& x, const_iterator i);
-    void splice_after(const_iterator p, forward_list& x,
-                      const_iterator first, const_iterator last);
-    void splice_after(const_iterator p, forward_list&& x,
-                      const_iterator first, const_iterator last);
-    size_type remove(const value_type& v);           // void before C++20
-    template <class Predicate>
-      size_type remove_if(Predicate pred);           // void before C++20
-    size_type unique();                              // void before C++20
-    template <class BinaryPredicate>
-      size_type unique(BinaryPredicate binary_pred); // void before C++20
-    void merge(forward_list& x);
-    void merge(forward_list&& x);
-    template <class Compare> void merge(forward_list& x, Compare comp);
-    template <class Compare> void merge(forward_list&& x, Compare comp);
-    void sort();
-    template <class Compare> void sort(Compare comp);
-    void reverse() noexcept;
-};
-
-
-template <class InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-    forward_list(InputIterator, InputIterator, Allocator = Allocator())
-    -> forward_list<typename iterator_traits<InputIterator>::value_type, Allocator>;  // C++17
-
-template <class T, class Allocator>
-    bool operator==(const forward_list<T, Allocator>& x,
-                    const forward_list<T, Allocator>& y);
-
-template <class T, class Allocator>
-    bool operator< (const forward_list<T, Allocator>& x,
-                    const forward_list<T, Allocator>& y);
-
-template <class T, class Allocator>
-    bool operator!=(const forward_list<T, Allocator>& x,
-                    const forward_list<T, Allocator>& y);
-
-template <class T, class Allocator>
-    bool operator> (const forward_list<T, Allocator>& x,
-                    const forward_list<T, Allocator>& y);
-
-template <class T, class Allocator>
-    bool operator>=(const forward_list<T, Allocator>& x,
-                    const forward_list<T, Allocator>& y);
-
-template <class T, class Allocator>
-    bool operator<=(const forward_list<T, Allocator>& x,
-                    const forward_list<T, Allocator>& y);
-
-template <class T, class Allocator>
-    void swap(forward_list<T, Allocator>& x, forward_list<T, Allocator>& y)
-         noexcept(noexcept(x.swap(y)));
-
-template <class T, class Allocator, class U>
-    typename forward_list<T, Allocator>::size_type
-    erase(forward_list<T, Allocator>& c, const U& value);       // C++20
-template <class T, class Allocator, class Predicate>
-    typename forward_list<T, Allocator>::size_type
-    erase_if(forward_list<T, Allocator>& c, Predicate pred);    // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/forward.list.syn.
 
 #include <__config>
 #include <__utility/forward.h>
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
--- a/libcxx/include/fstream
+++ b/libcxx/include/fstream
@@ -10,174 +10,7 @@
 #ifndef _LIBCPP_FSTREAM
 #define _LIBCPP_FSTREAM
 
-/*
-    fstream synopsis
-
-template <class charT, class traits = char_traits<charT> >
-class basic_filebuf
-    : public basic_streambuf<charT, traits>
-{
-public:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    // 27.9.1.2 Constructors/destructor:
-    basic_filebuf();
-    basic_filebuf(basic_filebuf&& rhs);
-    virtual ~basic_filebuf();
-
-    // 27.9.1.3 Assign/swap:
-    basic_filebuf& operator=(basic_filebuf&& rhs);
-    void swap(basic_filebuf& rhs);
-
-    // 27.9.1.4 Members:
-    bool is_open() const;
-    basic_filebuf* open(const char* s, ios_base::openmode mode);
-    basic_filebuf* open(const string& s, ios_base::openmode mode);
-    basic_filebuf* open(const filesystem::path& p, ios_base::openmode mode); // C++17
-    basic_filebuf* close();
-
-protected:
-    // 27.9.1.5 Overridden virtual functions:
-    virtual streamsize showmanyc();
-    virtual int_type underflow();
-    virtual int_type uflow();
-    virtual int_type pbackfail(int_type c = traits_type::eof());
-    virtual int_type overflow (int_type c = traits_type::eof());
-    virtual basic_streambuf<char_type, traits_type>* setbuf(char_type* s, streamsize n);
-    virtual pos_type seekoff(off_type off, ios_base::seekdir way,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual pos_type seekpos(pos_type sp,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual int sync();
-    virtual void imbue(const locale& loc);
-};
-
-template <class charT, class traits>
-  void
-  swap(basic_filebuf<charT, traits>& x, basic_filebuf<charT, traits>& y);
-
-typedef basic_filebuf<char>    filebuf;
-typedef basic_filebuf<wchar_t> wfilebuf;
-
-template <class charT, class traits = char_traits<charT> >
-class basic_ifstream
-    : public basic_istream<charT,traits>
-{
-public:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    basic_ifstream();
-    explicit basic_ifstream(const char* s, ios_base::openmode mode = ios_base::in);
-    explicit basic_ifstream(const string& s, ios_base::openmode mode = ios_base::in);
-    explicit basic_ifstream(const filesystem::path& p,
-                            ios_base::openmode mode = ios_base::in); // C++17
-    basic_ifstream(basic_ifstream&& rhs);
-
-    basic_ifstream& operator=(basic_ifstream&& rhs);
-    void swap(basic_ifstream& rhs);
-
-    basic_filebuf<char_type, traits_type>* rdbuf() const;
-    bool is_open() const;
-    void open(const char* s, ios_base::openmode mode = ios_base::in);
-    void open(const string& s, ios_base::openmode mode = ios_base::in);
-    void open(const filesystem::path& s, ios_base::openmode mode = ios_base::in); // C++17
-
-    void close();
-};
-
-template <class charT, class traits>
-  void
-  swap(basic_ifstream<charT, traits>& x, basic_ifstream<charT, traits>& y);
-
-typedef basic_ifstream<char>    ifstream;
-typedef basic_ifstream<wchar_t> wifstream;
-
-template <class charT, class traits = char_traits<charT> >
-class basic_ofstream
-    : public basic_ostream<charT,traits>
-{
-public:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    basic_ofstream();
-    explicit basic_ofstream(const char* s, ios_base::openmode mode = ios_base::out);
-    explicit basic_ofstream(const string& s, ios_base::openmode mode = ios_base::out);
-    explicit basic_ofstream(const filesystem::path& p,
-                            ios_base::openmode mode = ios_base::out); // C++17
-    basic_ofstream(basic_ofstream&& rhs);
-
-    basic_ofstream& operator=(basic_ofstream&& rhs);
-    void swap(basic_ofstream& rhs);
-
-    basic_filebuf<char_type, traits_type>* rdbuf() const;
-    bool is_open() const;
-    void open(const char* s, ios_base::openmode mode = ios_base::out);
-    void open(const string& s, ios_base::openmode mode = ios_base::out);
-    void open(const filesystem::path& p,
-              ios_base::openmode mode = ios_base::out); // C++17
-
-    void close();
-};
-
-template <class charT, class traits>
-  void
-  swap(basic_ofstream<charT, traits>& x, basic_ofstream<charT, traits>& y);
-
-typedef basic_ofstream<char>    ofstream;
-typedef basic_ofstream<wchar_t> wofstream;
-
-template <class charT, class traits=char_traits<charT> >
-class basic_fstream
-    : public basic_iostream<charT,traits>
-{
-public:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    basic_fstream();
-    explicit basic_fstream(const char* s, ios_base::openmode mode = ios_base::in|ios_base::out);
-    explicit basic_fstream(const string& s, ios_base::openmode mode = ios_base::in|ios_base::out);
-    explicit basic_fstream(const filesystem::path& p,
-                           ios_base::openmode mode = ios_base::in|ios_base::out); C++17
-    basic_fstream(basic_fstream&& rhs);
-
-    basic_fstream& operator=(basic_fstream&& rhs);
-    void swap(basic_fstream& rhs);
-
-    basic_filebuf<char_type, traits_type>* rdbuf() const;
-    bool is_open() const;
-    void open(const char* s, ios_base::openmode mode = ios_base::in|ios_base::out);
-    void open(const string& s, ios_base::openmode mode = ios_base::in|ios_base::out);
-    void open(const filesystem::path& s,
-              ios_base::openmode mode = ios_base::in|ios_base::out); // C++17
-
-    void close();
-};
-
-template <class charT, class traits>
-  void swap(basic_fstream<charT, traits>& x, basic_fstream<charT, traits>& y);
-
-typedef basic_fstream<char>    fstream;
-typedef basic_fstream<wchar_t> wfstream;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/fstream.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/functional b/libcxx/include/functional
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -10,482 +10,7 @@
 #ifndef _LIBCPP_FUNCTIONAL
 #define _LIBCPP_FUNCTIONAL
 
-/*
-    functional synopsis
-
-namespace std
-{
-
-template <class Arg, class Result>
-struct unary_function
-{
-    typedef Arg    argument_type;
-    typedef Result result_type;
-};
-
-template <class Arg1, class Arg2, class Result>
-struct binary_function
-{
-    typedef Arg1   first_argument_type;
-    typedef Arg2   second_argument_type;
-    typedef Result result_type;
-};
-
-template <class T>
-class reference_wrapper
-    : public unary_function<T1, R> // if wrapping a unary functor
-    : public binary_function<T1, T2, R> // if wraping a binary functor
-{
-public:
-    // types
-    typedef T type;
-    typedef see below result_type; // Not always defined
-
-    // construct/copy/destroy
-    template<class U>
-      reference_wrapper(U&&);
-    reference_wrapper(const reference_wrapper<T>& x) noexcept;
-
-    // assignment
-    reference_wrapper& operator=(const reference_wrapper<T>& x) noexcept;
-
-    // access
-    operator T& () const noexcept;
-    T& get() const noexcept;
-
-    // invoke
-    template <class... ArgTypes>
-      typename result_of<T&(ArgTypes&&...)>::type
-          operator() (ArgTypes&&...) const;
-};
-
-template <class T>
-  reference_wrapper(T&) -> reference_wrapper<T>;
-
-template <class T> reference_wrapper<T> ref(T& t) noexcept;
-template <class T> void ref(const T&& t) = delete;
-template <class T> reference_wrapper<T> ref(reference_wrapper<T>t) noexcept;
-
-template <class T> reference_wrapper<const T> cref(const T& t) noexcept;
-template <class T> void cref(const T&& t) = delete;
-template <class T> reference_wrapper<const T> cref(reference_wrapper<T> t) noexcept;
-
-template <class T> struct unwrap_reference;                                       // since C++20
-template <class T> struct unwrap_ref_decay : unwrap_reference<decay_t<T>> { };    // since C++20
-template <class T> using unwrap_reference_t = typename unwrap_reference<T>::type; // since C++20
-template <class T> using unwrap_ref_decay_t = typename unwrap_ref_decay<T>::type; // since C++20
-
-template <class T> // <class T=void> in C++14
-struct plus {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct minus {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct multiplies {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct divides {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct modulus {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct negate {
-    T operator()(const T& x) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct equal_to {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct not_equal_to {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct greater {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct less {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct greater_equal {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct less_equal {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct logical_and {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct logical_or {
-    bool operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct logical_not {
-    bool operator()(const T& x) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct bit_and {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct bit_or {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T> // <class T=void> in C++14
-struct bit_xor {
-    T operator()(const T& x, const T& y) const;
-};
-
-template <class T=void> // C++14
-struct bit_not {
-    T operator()(const T& x) const;
-};
-
-struct identity; // C++20
-
-template <class Predicate>
-class unary_negate // deprecated in C++17, removed in C++20
-    : public unary_function<typename Predicate::argument_type, bool>
-{
-public:
-    explicit unary_negate(const Predicate& pred);
-    bool operator()(const typename Predicate::argument_type& x) const;
-};
-
-template <class Predicate> // deprecated in C++17, removed in C++20
-unary_negate<Predicate> not1(const Predicate& pred);
-
-template <class Predicate>
-class binary_negate // deprecated in C++17, removed in C++20
-    : public binary_function<typename Predicate::first_argument_type,
-                             typename Predicate::second_argument_type,
-                             bool>
-{
-public:
-    explicit binary_negate(const Predicate& pred);
-    bool operator()(const typename Predicate::first_argument_type& x,
-                    const typename Predicate::second_argument_type& y) const;
-};
-
-template <class Predicate> // deprecated in C++17, removed in C++20
-binary_negate<Predicate> not2(const Predicate& pred);
-
-template <class F>
-constexpr unspecified not_fn(F&& f); // C++17, constexpr in C++20
-
-template<class T> struct is_bind_expression;
-template<class T> struct is_placeholder;
-
-    // See C++14 20.9.9, Function object binders
-template <class T> inline constexpr bool is_bind_expression_v
-  = is_bind_expression<T>::value; // C++17
-template <class T> inline constexpr int is_placeholder_v
-  = is_placeholder<T>::value; // C++17
-
-
-template<class Fn, class... BoundArgs>
-  constexpr unspecified bind(Fn&&, BoundArgs&&...);  // constexpr in C++20
-template<class R, class Fn, class... BoundArgs>
-  constexpr unspecified bind(Fn&&, BoundArgs&&...);  // constexpr in C++20
-
-template<class F, class... Args>
- constexpr // constexpr in C++20
- invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) // C++17
-    noexcept(is_nothrow_invocable_v<F, Args...>);
-
-namespace placeholders {
-  // M is the implementation-defined number of placeholders
-  extern unspecified _1;
-  extern unspecified _2;
-  .
-  .
-  .
-  extern unspecified _Mp;
-}
-
-template <class Operation>
-class binder1st     // deprecated in C++11, removed in C++17
-    : public unary_function<typename Operation::second_argument_type,
-                            typename Operation::result_type>
-{
-protected:
-    Operation                               op;
-    typename Operation::first_argument_type value;
-public:
-    binder1st(const Operation& x, const typename Operation::first_argument_type y);
-    typename Operation::result_type operator()(      typename Operation::second_argument_type& x) const;
-    typename Operation::result_type operator()(const typename Operation::second_argument_type& x) const;
-};
-
-template <class Operation, class T>
-binder1st<Operation> bind1st(const Operation& op, const T& x);  // deprecated in C++11, removed in C++17
-
-template <class Operation>
-class binder2nd     // deprecated in C++11, removed in C++17
-    : public unary_function<typename Operation::first_argument_type,
-                            typename Operation::result_type>
-{
-protected:
-    Operation                                op;
-    typename Operation::second_argument_type value;
-public:
-    binder2nd(const Operation& x, const typename Operation::second_argument_type y);
-    typename Operation::result_type operator()(      typename Operation::first_argument_type& x) const;
-    typename Operation::result_type operator()(const typename Operation::first_argument_type& x) const;
-};
-
-template <class Operation, class T>
-binder2nd<Operation> bind2nd(const Operation& op, const T& x);  // deprecated in C++11, removed in C++17
-
-template <class Arg, class Result>      // deprecated in C++11, removed in C++17
-class pointer_to_unary_function : public unary_function<Arg, Result>
-{
-public:
-    explicit pointer_to_unary_function(Result (*f)(Arg));
-    Result operator()(Arg x) const;
-};
-
-template <class Arg, class Result>
-pointer_to_unary_function<Arg,Result> ptr_fun(Result (*f)(Arg));      // deprecated in C++11, removed in C++17
-
-template <class Arg1, class Arg2, class Result>      // deprecated in C++11, removed in C++17
-class pointer_to_binary_function : public binary_function<Arg1, Arg2, Result>
-{
-public:
-    explicit pointer_to_binary_function(Result (*f)(Arg1, Arg2));
-    Result operator()(Arg1 x, Arg2 y) const;
-};
-
-template <class Arg1, class Arg2, class Result>
-pointer_to_binary_function<Arg1,Arg2,Result> ptr_fun(Result (*f)(Arg1,Arg2));      // deprecated in C++11, removed in C++17
-
-template<class S, class T>      // deprecated in C++11, removed in C++17
-class mem_fun_t : public unary_function<T*, S>
-{
-public:
-    explicit mem_fun_t(S (T::*p)());
-    S operator()(T* p) const;
-};
-
-template<class S, class T, class A>
-class mem_fun1_t : public binary_function<T*, A, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit mem_fun1_t(S (T::*p)(A));
-    S operator()(T* p, A x) const;
-};
-
-template<class S, class T>          mem_fun_t<S,T>    mem_fun(S (T::*f)());      // deprecated in C++11, removed in C++17
-template<class S, class T, class A> mem_fun1_t<S,T,A> mem_fun(S (T::*f)(A));     // deprecated in C++11, removed in C++17
-
-template<class S, class T>
-class mem_fun_ref_t : public unary_function<T, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit mem_fun_ref_t(S (T::*p)());
-    S operator()(T& p) const;
-};
-
-template<class S, class T, class A>
-class mem_fun1_ref_t : public binary_function<T, A, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit mem_fun1_ref_t(S (T::*p)(A));
-    S operator()(T& p, A x) const;
-};
-
-template<class S, class T>          mem_fun_ref_t<S,T>    mem_fun_ref(S (T::*f)());      // deprecated in C++11, removed in C++17
-template<class S, class T, class A> mem_fun1_ref_t<S,T,A> mem_fun_ref(S (T::*f)(A));     // deprecated in C++11, removed in C++17
-
-template <class S, class T>
-class const_mem_fun_t : public unary_function<const T*, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit const_mem_fun_t(S (T::*p)() const);
-    S operator()(const T* p) const;
-};
-
-template <class S, class T, class A>
-class const_mem_fun1_t : public binary_function<const T*, A, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit const_mem_fun1_t(S (T::*p)(A) const);
-    S operator()(const T* p, A x) const;
-};
-
-template <class S, class T>          const_mem_fun_t<S,T>    mem_fun(S (T::*f)() const);      // deprecated in C++11, removed in C++17
-template <class S, class T, class A> const_mem_fun1_t<S,T,A> mem_fun(S (T::*f)(A) const);     // deprecated in C++11, removed in C++17
-
-template <class S, class T>
-class const_mem_fun_ref_t : public unary_function<T, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit const_mem_fun_ref_t(S (T::*p)() const);
-    S operator()(const T& p) const;
-};
-
-template <class S, class T, class A>
-class const_mem_fun1_ref_t : public binary_function<T, A, S>      // deprecated in C++11, removed in C++17
-{
-public:
-    explicit const_mem_fun1_ref_t(S (T::*p)(A) const);
-    S operator()(const T& p, A x) const;
-};
-
-template <class S, class T>          const_mem_fun_ref_t<S,T>    mem_fun_ref(S (T::*f)() const);   // deprecated in C++11, removed in C++17
-template <class S, class T, class A> const_mem_fun1_ref_t<S,T,A> mem_fun_ref(S (T::*f)(A) const);  // deprecated in C++11, removed in C++17
-
-template<class R, class T>
-constexpr unspecified mem_fn(R T::*); // constexpr in C++20
-
-class bad_function_call
-    : public exception
-{
-};
-
-template<class> class function; // undefined
-
-template<class R, class... ArgTypes>
-class function<R(ArgTypes...)>
-  : public unary_function<T1, R>      // iff sizeof...(ArgTypes) == 1 and
-                                      // ArgTypes contains T1
-  : public binary_function<T1, T2, R> // iff sizeof...(ArgTypes) == 2 and
-                                      // ArgTypes contains T1 and T2
-{
-public:
-    typedef R result_type;
-
-    // construct/copy/destroy:
-    function() noexcept;
-    function(nullptr_t) noexcept;
-    function(const function&);
-    function(function&&) noexcept;
-    template<class F>
-      function(F);
-    template<Allocator Alloc>
-      function(allocator_arg_t, const Alloc&) noexcept;            // removed in C++17
-    template<Allocator Alloc>
-      function(allocator_arg_t, const Alloc&, nullptr_t) noexcept; // removed in C++17
-    template<Allocator Alloc>
-      function(allocator_arg_t, const Alloc&, const function&);    // removed in C++17
-    template<Allocator Alloc>
-      function(allocator_arg_t, const Alloc&, function&&);         // removed in C++17
-    template<class F, Allocator Alloc>
-      function(allocator_arg_t, const Alloc&, F);                  // removed in C++17
-
-    function& operator=(const function&);
-    function& operator=(function&&) noexcept;
-    function& operator=(nullptr_t) noexcept;
-    template<class F>
-      function& operator=(F&&);
-    template<class F>
-      function& operator=(reference_wrapper<F>) noexcept;
-
-    ~function();
-
-    // function modifiers:
-    void swap(function&) noexcept;
-    template<class F, class Alloc>
-      void assign(F&&, const Alloc&);                 // Removed in C++17
-
-    // function capacity:
-    explicit operator bool() const noexcept;
-
-    // function invocation:
-    R operator()(ArgTypes...) const;
-
-    // function target access:
-    const std::type_info& target_type() const noexcept;
-    template <typename T>       T* target() noexcept;
-    template <typename T> const T* target() const noexcept;
-};
-
-// Deduction guides
-template<class R, class ...Args>
-function(R(*)(Args...)) -> function<R(Args...)>; // since C++17
-
-template<class F>
-function(F) -> function<see-below>; // since C++17
-
-// Null pointer comparisons:
-template <class R, class ... ArgTypes>
-  bool operator==(const function<R(ArgTypes...)>&, nullptr_t) noexcept;
-
-template <class R, class ... ArgTypes>
-  bool operator==(nullptr_t, const function<R(ArgTypes...)>&) noexcept;
-
-template <class R, class ... ArgTypes>
-  bool operator!=(const function<R(ArgTypes...)>&, nullptr_t) noexcept;
-
-template <class  R, class ... ArgTypes>
-  bool operator!=(nullptr_t, const function<R(ArgTypes...)>&) noexcept;
-
-// specialized algorithms:
-template <class  R, class ... ArgTypes>
-  void swap(function<R(ArgTypes...)>&, function<R(ArgTypes...)>&) noexcept;
-
-template <class T> struct hash;
-
-template <> struct hash<bool>;
-template <> struct hash<char>;
-template <> struct hash<signed char>;
-template <> struct hash<unsigned char>;
-template <> struct hash<char8_t>; // since C++20
-template <> struct hash<char16_t>;
-template <> struct hash<char32_t>;
-template <> struct hash<wchar_t>;
-template <> struct hash<short>;
-template <> struct hash<unsigned short>;
-template <> struct hash<int>;
-template <> struct hash<unsigned int>;
-template <> struct hash<long>;
-template <> struct hash<long long>;
-template <> struct hash<unsigned long>;
-template <> struct hash<unsigned long long>;
-
-template <> struct hash<float>;
-template <> struct hash<double>;
-template <> struct hash<long double>;
-
-template<class T> struct hash<T*>;
-template <> struct hash<nullptr_t>;  // C++17
-
-}  // std
-
-POLICY:  For non-variadic implementations, the number of arguments is limited
-         to 3.  It is hoped that the need for non-variadic implementations
-         will be minimal.
-
-*/
+// Synopsis avaiable at http://wg21.link/functional.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/future b/libcxx/include/future
--- a/libcxx/include/future
+++ b/libcxx/include/future
@@ -10,356 +10,7 @@
 #ifndef _LIBCPP_FUTURE
 #define _LIBCPP_FUTURE
 
-/*
-    future synopsis
-
-namespace std
-{
-
-enum class future_errc
-{
-    future_already_retrieved = 1,
-    promise_already_satisfied,
-    no_state,
-    broken_promise
-};
-
-enum class launch
-{
-    async = 1,
-    deferred = 2,
-    any = async | deferred
-};
-
-enum class future_status
-{
-    ready,
-    timeout,
-    deferred
-};
-
-template <> struct is_error_code_enum<future_errc> : public true_type { };
-error_code make_error_code(future_errc e) noexcept;
-error_condition make_error_condition(future_errc e) noexcept;
-
-const error_category& future_category() noexcept;
-
-class future_error
-    : public logic_error
-{
-public:
-    future_error(error_code ec);  // exposition only
-    explicit future_error(future_errc); // C++17
-    const error_code& code() const noexcept;
-    const char*       what() const noexcept;
-};
-
-template <class R>
-class promise
-{
-public:
-    promise();
-    template <class Allocator>
-        promise(allocator_arg_t, const Allocator& a);
-    promise(promise&& rhs) noexcept;
-    promise(const promise& rhs) = delete;
-    ~promise();
-
-    // assignment
-    promise& operator=(promise&& rhs) noexcept;
-    promise& operator=(const promise& rhs) = delete;
-    void swap(promise& other) noexcept;
-
-    // retrieving the result
-    future<R> get_future();
-
-    // setting the result
-    void set_value(const R& r);
-    void set_value(R&& r);
-    void set_exception(exception_ptr p);
-
-    // setting the result with deferred notification
-    void set_value_at_thread_exit(const R& r);
-    void set_value_at_thread_exit(R&& r);
-    void set_exception_at_thread_exit(exception_ptr p);
-};
-
-template <class R>
-class promise<R&>
-{
-public:
-    promise();
-    template <class Allocator>
-        promise(allocator_arg_t, const Allocator& a);
-    promise(promise&& rhs) noexcept;
-    promise(const promise& rhs) = delete;
-    ~promise();
-
-    // assignment
-    promise& operator=(promise&& rhs) noexcept;
-    promise& operator=(const promise& rhs) = delete;
-    void swap(promise& other) noexcept;
-
-    // retrieving the result
-    future<R&> get_future();
-
-    // setting the result
-    void set_value(R& r);
-    void set_exception(exception_ptr p);
-
-    // setting the result with deferred notification
-    void set_value_at_thread_exit(R&);
-    void set_exception_at_thread_exit(exception_ptr p);
-};
-
-template <>
-class promise<void>
-{
-public:
-    promise();
-    template <class Allocator>
-        promise(allocator_arg_t, const Allocator& a);
-    promise(promise&& rhs) noexcept;
-    promise(const promise& rhs) = delete;
-    ~promise();
-
-    // assignment
-    promise& operator=(promise&& rhs) noexcept;
-    promise& operator=(const promise& rhs) = delete;
-    void swap(promise& other) noexcept;
-
-    // retrieving the result
-    future<void> get_future();
-
-    // setting the result
-    void set_value();
-    void set_exception(exception_ptr p);
-
-    // setting the result with deferred notification
-    void set_value_at_thread_exit();
-    void set_exception_at_thread_exit(exception_ptr p);
-};
-
-template <class R> void swap(promise<R>& x, promise<R>& y) noexcept;
-
-template <class R, class Alloc>
-    struct uses_allocator<promise<R>, Alloc> : public true_type {};
-
-template <class R>
-class future
-{
-public:
-    future() noexcept;
-    future(future&&) noexcept;
-    future(const future& rhs) = delete;
-    ~future();
-    future& operator=(const future& rhs) = delete;
-    future& operator=(future&&) noexcept;
-    shared_future<R> share() noexcept;
-
-    // retrieving the value
-    R get();
-
-    // functions to check state
-    bool valid() const noexcept;
-
-    void wait() const;
-    template <class Rep, class Period>
-        future_status
-        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
-    template <class Clock, class Duration>
-        future_status
-        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
-};
-
-template <class R>
-class future<R&>
-{
-public:
-    future() noexcept;
-    future(future&&) noexcept;
-    future(const future& rhs) = delete;
-    ~future();
-    future& operator=(const future& rhs) = delete;
-    future& operator=(future&&) noexcept;
-    shared_future<R&> share() noexcept;
-
-    // retrieving the value
-    R& get();
-
-    // functions to check state
-    bool valid() const noexcept;
-
-    void wait() const;
-    template <class Rep, class Period>
-        future_status
-        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
-    template <class Clock, class Duration>
-        future_status
-        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
-};
-
-template <>
-class future<void>
-{
-public:
-    future() noexcept;
-    future(future&&) noexcept;
-    future(const future& rhs) = delete;
-    ~future();
-    future& operator=(const future& rhs) = delete;
-    future& operator=(future&&) noexcept;
-    shared_future<void> share() noexcept;
-
-    // retrieving the value
-    void get();
-
-    // functions to check state
-    bool valid() const noexcept;
-
-    void wait() const;
-    template <class Rep, class Period>
-        future_status
-        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
-    template <class Clock, class Duration>
-        future_status
-        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
-};
-
-template <class R>
-class shared_future
-{
-public:
-    shared_future() noexcept;
-    shared_future(const shared_future& rhs);
-    shared_future(future<R>&&) noexcept;
-    shared_future(shared_future&& rhs) noexcept;
-    ~shared_future();
-    shared_future& operator=(const shared_future& rhs);
-    shared_future& operator=(shared_future&& rhs) noexcept;
-
-    // retrieving the value
-    const R& get() const;
-
-    // functions to check state
-    bool valid() const noexcept;
-
-    void wait() const;
-    template <class Rep, class Period>
-        future_status
-        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
-    template <class Clock, class Duration>
-        future_status
-        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
-};
-
-template <class R>
-class shared_future<R&>
-{
-public:
-    shared_future() noexcept;
-    shared_future(const shared_future& rhs);
-    shared_future(future<R&>&&) noexcept;
-    shared_future(shared_future&& rhs) noexcept;
-    ~shared_future();
-    shared_future& operator=(const shared_future& rhs);
-    shared_future& operator=(shared_future&& rhs) noexcept;
-
-    // retrieving the value
-    R& get() const;
-
-    // functions to check state
-    bool valid() const noexcept;
-
-    void wait() const;
-    template <class Rep, class Period>
-        future_status
-        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
-    template <class Clock, class Duration>
-        future_status
-        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
-};
-
-template <>
-class shared_future<void>
-{
-public:
-    shared_future() noexcept;
-    shared_future(const shared_future& rhs);
-    shared_future(future<void>&&) noexcept;
-    shared_future(shared_future&& rhs) noexcept;
-    ~shared_future();
-    shared_future& operator=(const shared_future& rhs);
-    shared_future& operator=(shared_future&& rhs) noexcept;
-
-    // retrieving the value
-    void get() const;
-
-    // functions to check state
-    bool valid() const noexcept;
-
-    void wait() const;
-    template <class Rep, class Period>
-        future_status
-        wait_for(const chrono::duration<Rep, Period>& rel_time) const;
-    template <class Clock, class Duration>
-        future_status
-        wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
-};
-
-template <class F, class... Args>
-  future<typename result_of<typename decay<F>::type(typename decay<Args>::type...)>::type>
-  async(F&& f, Args&&... args);
-
-template <class F, class... Args>
-  future<typename result_of<typename decay<F>::type(typename decay<Args>::type...)>::type>
-  async(launch policy, F&& f, Args&&... args);
-
-template <class> class packaged_task; // undefined
-
-template <class R, class... ArgTypes>
-class packaged_task<R(ArgTypes...)>
-{
-public:
-    typedef R result_type; // extension
-
-    // construction and destruction
-    packaged_task() noexcept;
-    template <class F>
-        explicit packaged_task(F&& f);
-    template <class F, class Allocator>
-        packaged_task(allocator_arg_t, const Allocator& a, F&& f);
-    ~packaged_task();
-
-    // no copy
-    packaged_task(const packaged_task&) = delete;
-    packaged_task& operator=(const packaged_task&) = delete;
-
-    // move support
-    packaged_task(packaged_task&& other) noexcept;
-    packaged_task& operator=(packaged_task&& other) noexcept;
-    void swap(packaged_task& other) noexcept;
-
-    bool valid() const noexcept;
-
-    // result retrieval
-    future<R> get_future();
-
-    // execution
-    void operator()(ArgTypes... );
-    void make_ready_at_thread_exit(ArgTypes...);
-
-    void reset();
-};
-
-template <class R>
-  void swap(packaged_task<R(ArgTypes...)&, packaged_task<R(ArgTypes...)>&) noexcept;
-
-template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/future.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/initializer_list b/libcxx/include/initializer_list
--- a/libcxx/include/initializer_list
+++ b/libcxx/include/initializer_list
@@ -10,37 +10,7 @@
 #ifndef _LIBCPP_INITIALIZER_LIST
 #define _LIBCPP_INITIALIZER_LIST
 
-/*
-    initializer_list synopsis
-
-namespace std
-{
-
-template<class E>
-class initializer_list
-{
-public:
-    typedef E        value_type;
-    typedef const E& reference;
-    typedef const E& const_reference;
-    typedef size_t   size_type;
-
-    typedef const E* iterator;
-    typedef const E* const_iterator;
-
-    initializer_list() noexcept; // constexpr in C++14
-
-    size_t   size()  const noexcept; // constexpr in C++14
-    const E* begin() const noexcept; // constexpr in C++14
-    const E* end()   const noexcept; // constexpr in C++14
-};
-
-template<class E> const E* begin(initializer_list<E> il) noexcept; // constexpr in C++14
-template<class E> const E* end(initializer_list<E> il) noexcept; // constexpr in C++14
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/initializer.list.syn.
 
 #include <__config>
 #include <cstddef>
diff --git a/libcxx/include/iomanip b/libcxx/include/iomanip
--- a/libcxx/include/iomanip
+++ b/libcxx/include/iomanip
@@ -10,37 +10,7 @@
 #ifndef _LIBCPP_IOMANIP
 #define _LIBCPP_IOMANIP
 
-/*
-    iomanip synopsis
-
-namespace std {
-
-// types T1, T2, ... are unspecified implementation types
-T1 resetiosflags(ios_base::fmtflags mask);
-T2 setiosflags (ios_base::fmtflags mask);
-T3 setbase(int base);
-template<charT> T4 setfill(charT c);
-T5 setprecision(int n);
-T6 setw(int n);
-template <class moneyT> T7 get_money(moneyT& mon, bool intl = false);
-template <class charT, class moneyT> T8 put_money(const moneyT& mon, bool intl = false);
-template <class charT> T9 get_time(struct tm* tmb, const charT* fmt);
-template <class charT> T10 put_time(const struct tm* tmb, const charT* fmt);
-
-template <class charT>
-  T11 quoted(const charT* s, charT delim=charT('"'), charT escape=charT('\\')); // C++14
-
-template <class charT, class traits, class Allocator>
-  T12 quoted(const basic_string<charT, traits, Allocator>& s,
-             charT delim=charT('"'), charT escape=charT('\\')); // C++14
-
-template <class charT, class traits, class Allocator>
-  T13 quoted(basic_string<charT, traits, Allocator>& s,
-             charT delim=charT('"'), charT escape=charT('\\')); // C++14
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/iomanip.syn.
 
 #include <__config>
 #include <__string>
diff --git a/libcxx/include/ios b/libcxx/include/ios
--- a/libcxx/include/ios
+++ b/libcxx/include/ios
@@ -10,205 +10,7 @@
 #ifndef _LIBCPP_IOS
 #define _LIBCPP_IOS
 
-/*
-    ios synopsis
-
-#include <iosfwd>
-
-namespace std
-{
-
-typedef OFF_T streamoff;
-typedef SZ_T streamsize;
-template <class stateT> class fpos;
-
-class ios_base
-{
-public:
-    class failure;
-
-    typedef T1 fmtflags;
-    static constexpr fmtflags boolalpha;
-    static constexpr fmtflags dec;
-    static constexpr fmtflags fixed;
-    static constexpr fmtflags hex;
-    static constexpr fmtflags internal;
-    static constexpr fmtflags left;
-    static constexpr fmtflags oct;
-    static constexpr fmtflags right;
-    static constexpr fmtflags scientific;
-    static constexpr fmtflags showbase;
-    static constexpr fmtflags showpoint;
-    static constexpr fmtflags showpos;
-    static constexpr fmtflags skipws;
-    static constexpr fmtflags unitbuf;
-    static constexpr fmtflags uppercase;
-    static constexpr fmtflags adjustfield;
-    static constexpr fmtflags basefield;
-    static constexpr fmtflags floatfield;
-
-    typedef T2 iostate;
-    static constexpr iostate badbit;
-    static constexpr iostate eofbit;
-    static constexpr iostate failbit;
-    static constexpr iostate goodbit;
-
-    typedef T3 openmode;
-    static constexpr openmode app;
-    static constexpr openmode ate;
-    static constexpr openmode binary;
-    static constexpr openmode in;
-    static constexpr openmode out;
-    static constexpr openmode trunc;
-
-    typedef T4 seekdir;
-    static constexpr seekdir beg;
-    static constexpr seekdir cur;
-    static constexpr seekdir end;
-
-    class Init;
-
-    // 27.5.2.2 fmtflags state:
-    fmtflags flags() const;
-    fmtflags flags(fmtflags fmtfl);
-    fmtflags setf(fmtflags fmtfl);
-    fmtflags setf(fmtflags fmtfl, fmtflags mask);
-    void unsetf(fmtflags mask);
-
-    streamsize precision() const;
-    streamsize precision(streamsize prec);
-    streamsize width() const;
-    streamsize width(streamsize wide);
-
-    // 27.5.2.3 locales:
-    locale imbue(const locale& loc);
-    locale getloc() const;
-
-    // 27.5.2.5 storage:
-    static int xalloc();
-    long& iword(int index);
-    void*& pword(int index);
-
-    // destructor
-    virtual ~ios_base();
-
-    // 27.5.2.6 callbacks;
-    enum event { erase_event, imbue_event, copyfmt_event };
-    typedef void (*event_callback)(event, ios_base&, int index);
-    void register_callback(event_callback fn, int index);
-
-    ios_base(const ios_base&) = delete;
-    ios_base& operator=(const ios_base&) = delete;
-
-    static bool sync_with_stdio(bool sync = true);
-
-protected:
-    ios_base();
-};
-
-template <class charT, class traits = char_traits<charT> >
-class basic_ios
-    : public ios_base
-{
-public:
-    // types:
-    typedef charT char_type;
-    typedef typename traits::int_type int_type;  // removed in C++17
-    typedef typename traits::pos_type pos_type;  // removed in C++17
-    typedef typename traits::off_type off_type;  // removed in C++17
-    typedef traits traits_type;
-
-    operator unspecified-bool-type() const;
-    bool operator!() const;
-    iostate rdstate() const;
-    void clear(iostate state = goodbit);
-    void setstate(iostate state);
-    bool good() const;
-    bool eof() const;
-    bool fail() const;
-    bool bad() const;
-
-    iostate exceptions() const;
-    void exceptions(iostate except);
-
-    // 27.5.4.1 Constructor/destructor:
-    explicit basic_ios(basic_streambuf<charT,traits>* sb);
-    virtual ~basic_ios();
-
-    // 27.5.4.2 Members:
-    basic_ostream<charT,traits>* tie() const;
-    basic_ostream<charT,traits>* tie(basic_ostream<charT,traits>* tiestr);
-
-    basic_streambuf<charT,traits>* rdbuf() const;
-    basic_streambuf<charT,traits>* rdbuf(basic_streambuf<charT,traits>* sb);
-
-    basic_ios& copyfmt(const basic_ios& rhs);
-
-    char_type fill() const;
-    char_type fill(char_type ch);
-
-    locale imbue(const locale& loc);
-
-    char narrow(char_type c, char dfault) const;
-    char_type widen(char c) const;
-
-    basic_ios(const basic_ios& ) = delete;
-    basic_ios& operator=(const basic_ios&) = delete;
-
-protected:
-    basic_ios();
-    void init(basic_streambuf<charT,traits>* sb);
-    void move(basic_ios& rhs);
-    void swap(basic_ios& rhs) noexcept;
-    void set_rdbuf(basic_streambuf<charT, traits>* sb);
-};
-
-// 27.5.5, manipulators:
-ios_base& boolalpha (ios_base& str);
-ios_base& noboolalpha(ios_base& str);
-ios_base& showbase (ios_base& str);
-ios_base& noshowbase (ios_base& str);
-ios_base& showpoint (ios_base& str);
-ios_base& noshowpoint(ios_base& str);
-ios_base& showpos (ios_base& str);
-ios_base& noshowpos (ios_base& str);
-ios_base& skipws (ios_base& str);
-ios_base& noskipws (ios_base& str);
-ios_base& uppercase (ios_base& str);
-ios_base& nouppercase(ios_base& str);
-ios_base& unitbuf (ios_base& str);
-ios_base& nounitbuf (ios_base& str);
-
-// 27.5.5.2 adjustfield:
-ios_base& internal (ios_base& str);
-ios_base& left (ios_base& str);
-ios_base& right (ios_base& str);
-
-// 27.5.5.3 basefield:
-ios_base& dec (ios_base& str);
-ios_base& hex (ios_base& str);
-ios_base& oct (ios_base& str);
-
-// 27.5.5.4 floatfield:
-ios_base& fixed (ios_base& str);
-ios_base& scientific (ios_base& str);
-ios_base& hexfloat (ios_base& str);
-ios_base& defaultfloat(ios_base& str);
-
-// 27.5.5.5 error reporting:
-enum class io_errc
-{
-    stream = 1
-};
-
-concept_map ErrorCodeEnum<io_errc> { };
-error_code make_error_code(io_errc e) noexcept;
-error_condition make_error_condition(io_errc e) noexcept;
-storage-class-specifier const error_category& iostream_category() noexcept;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/ios.syn.
 
 #include <__config>
 #include <__locale>
diff --git a/libcxx/include/iosfwd b/libcxx/include/iosfwd
--- a/libcxx/include/iosfwd
+++ b/libcxx/include/iosfwd
@@ -10,89 +10,7 @@
 #ifndef _LIBCPP_IOSFWD
 #define _LIBCPP_IOSFWD
 
-/*
-    iosfwd synopsis
-
-namespace std
-{
-
-template<class charT> struct char_traits;
-template<>            struct char_traits<char>;
-template<>            struct char_traits<char8_t>;  // C++20
-template<>            struct char_traits<char16_t>;
-template<>            struct char_traits<char32_t>;
-template<>            struct char_traits<wchar_t>;
-
-template<class T>     class allocator;
-
-class ios_base;
-template <class charT, class traits = char_traits<charT> > class basic_ios;
-
-template <class charT, class traits = char_traits<charT> > class basic_streambuf;
-template <class charT, class traits = char_traits<charT> > class basic_istream;
-template <class charT, class traits = char_traits<charT> > class basic_ostream;
-template <class charT, class traits = char_traits<charT> > class basic_iostream;
-
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-    class basic_stringbuf;
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-    class basic_istringstream;
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-    class basic_ostringstream;
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-    class basic_stringstream;
-
-template <class charT, class traits = char_traits<charT> > class basic_filebuf;
-template <class charT, class traits = char_traits<charT> > class basic_ifstream;
-template <class charT, class traits = char_traits<charT> > class basic_ofstream;
-template <class charT, class traits = char_traits<charT> > class basic_fstream;
-
-template <class charT, class traits = char_traits<charT> > class istreambuf_iterator;
-template <class charT, class traits = char_traits<charT> > class ostreambuf_iterator;
-
-typedef basic_ios<char>              ios;
-typedef basic_ios<wchar_t>           wios;
-
-typedef basic_streambuf<char>        streambuf;
-typedef basic_istream<char>          istream;
-typedef basic_ostream<char>          ostream;
-typedef basic_iostream<char>         iostream;
-
-typedef basic_stringbuf<char>        stringbuf;
-typedef basic_istringstream<char>    istringstream;
-typedef basic_ostringstream<char>    ostringstream;
-typedef basic_stringstream<char>     stringstream;
-
-typedef basic_filebuf<char>          filebuf;
-typedef basic_ifstream<char>         ifstream;
-typedef basic_ofstream<char>         ofstream;
-typedef basic_fstream<char>          fstream;
-
-typedef basic_streambuf<wchar_t>     wstreambuf;
-typedef basic_istream<wchar_t>       wistream;
-typedef basic_ostream<wchar_t>       wostream;
-typedef basic_iostream<wchar_t>      wiostream;
-
-typedef basic_stringbuf<wchar_t>     wstringbuf;
-typedef basic_istringstream<wchar_t> wistringstream;
-typedef basic_ostringstream<wchar_t> wostringstream;
-typedef basic_stringstream<wchar_t>  wstringstream;
-
-typedef basic_filebuf<wchar_t>       wfilebuf;
-typedef basic_ifstream<wchar_t>      wifstream;
-typedef basic_ofstream<wchar_t>      wofstream;
-typedef basic_fstream<wchar_t>       wfstream;
-
-template <class state> class fpos;
-using streampos  = fpos<char_traits<char>::state_type>;
-using wstreampos = fpos<char_traits<wchar_t>::state_type>;
-using u8streampos = fpos<char_traits<char8_t>::state_type>; // C++20
-using u16streampos = fpos<char_traits<char16_t>::state_type>;
-using u32streampos = fpos<char_traits<char32_t>::state_type>;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/iosfwd.syn.
 
 #include <__config>
 #include <wchar.h>  // for mbstate_t
diff --git a/libcxx/include/iostream b/libcxx/include/iostream
--- a/libcxx/include/iostream
+++ b/libcxx/include/iostream
@@ -10,28 +10,7 @@
 #ifndef _LIBCPP_IOSTREAM
 #define _LIBCPP_IOSTREAM
 
-/*
-    iostream synopsis
-
-#include <ios>
-#include <istream>
-#include <ostream>
-#include <streambuf>
-
-namespace std {
-
-extern istream cin;
-extern ostream cout;
-extern ostream cerr;
-extern ostream clog;
-extern wistream wcin;
-extern wostream wcout;
-extern wostream wcerr;
-extern wostream wclog;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/iostream.syn.
 
 #include <__config>
 #include <ios>
diff --git a/libcxx/include/istream b/libcxx/include/istream
--- a/libcxx/include/istream
+++ b/libcxx/include/istream
@@ -10,153 +10,7 @@
 #ifndef _LIBCPP_ISTREAM
 #define _LIBCPP_ISTREAM
 
-/*
-    istream synopsis
-
-template <class charT, class traits = char_traits<charT> >
-class basic_istream
-    : virtual public basic_ios<charT,traits>
-{
-public:
-    // types (inherited from basic_ios (27.5.4)):
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    // 27.7.1.1.1 Constructor/destructor:
-    explicit basic_istream(basic_streambuf<char_type, traits_type>* sb);
-    basic_istream(basic_istream&& rhs);
-    virtual ~basic_istream();
-
-    // 27.7.1.1.2 Assign/swap:
-    basic_istream& operator=(basic_istream&& rhs);
-    void swap(basic_istream& rhs);
-
-    // 27.7.1.1.3 Prefix/suffix:
-    class sentry;
-
-    // 27.7.1.2 Formatted input:
-    basic_istream& operator>>(basic_istream& (*pf)(basic_istream&));
-    basic_istream& operator>>(basic_ios<char_type, traits_type>&
-                              (*pf)(basic_ios<char_type, traits_type>&));
-    basic_istream& operator>>(ios_base& (*pf)(ios_base&));
-    basic_istream& operator>>(basic_streambuf<char_type, traits_type>* sb);
-    basic_istream& operator>>(bool& n);
-    basic_istream& operator>>(short& n);
-    basic_istream& operator>>(unsigned short& n);
-    basic_istream& operator>>(int& n);
-    basic_istream& operator>>(unsigned int& n);
-    basic_istream& operator>>(long& n);
-    basic_istream& operator>>(unsigned long& n);
-    basic_istream& operator>>(long long& n);
-    basic_istream& operator>>(unsigned long long& n);
-    basic_istream& operator>>(float& f);
-    basic_istream& operator>>(double& f);
-    basic_istream& operator>>(long double& f);
-    basic_istream& operator>>(void*& p);
-
-    // 27.7.1.3 Unformatted input:
-    streamsize gcount() const;
-    int_type get();
-    basic_istream& get(char_type& c);
-    basic_istream& get(char_type* s, streamsize n);
-    basic_istream& get(char_type* s, streamsize n, char_type delim);
-    basic_istream& get(basic_streambuf<char_type,traits_type>& sb);
-    basic_istream& get(basic_streambuf<char_type,traits_type>& sb, char_type delim);
-
-    basic_istream& getline(char_type* s, streamsize n);
-    basic_istream& getline(char_type* s, streamsize n, char_type delim);
-
-    basic_istream& ignore(streamsize n = 1, int_type delim = traits_type::eof());
-    int_type peek();
-    basic_istream& read (char_type* s, streamsize n);
-    streamsize readsome(char_type* s, streamsize n);
-
-    basic_istream& putback(char_type c);
-    basic_istream& unget();
-    int sync();
-
-    pos_type tellg();
-    basic_istream& seekg(pos_type);
-    basic_istream& seekg(off_type, ios_base::seekdir);
-protected:
-    basic_istream(const basic_istream& rhs) = delete;
-    basic_istream(basic_istream&& rhs);
-    // 27.7.2.1.2 Assign/swap:
-    basic_istream& operator=(const basic_istream& rhs) = delete;
-    basic_istream& operator=(basic_istream&& rhs);
-    void swap(basic_istream& rhs);
-};
-
-// 27.7.1.2.3 character extraction templates:
-template<class charT, class traits>
-  basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>&, charT&);
-
-template<class traits>
-  basic_istream<char,traits>& operator>>(basic_istream<char,traits>&, unsigned char&);
-
-template<class traits>
-  basic_istream<char,traits>& operator>>(basic_istream<char,traits>&, signed char&);
-
-template<class charT, class traits>
-  basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>&, charT*);
-
-template<class traits>
-  basic_istream<char,traits>& operator>>(basic_istream<char,traits>&, unsigned char*);
-
-template<class traits>
-  basic_istream<char,traits>& operator>>(basic_istream<char,traits>&, signed char*);
-
-template <class charT, class traits>
-  void
-  swap(basic_istream<charT, traits>& x, basic_istream<charT, traits>& y);
-
-typedef basic_istream<char> istream;
-typedef basic_istream<wchar_t> wistream;
-
-template <class charT, class traits = char_traits<charT> >
-class basic_iostream :
-    public basic_istream<charT,traits>,
-    public basic_ostream<charT,traits>
-{
-public:
-    // types:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    // constructor/destructor
-    explicit basic_iostream(basic_streambuf<char_type, traits_type>* sb);
-    basic_iostream(basic_iostream&& rhs);
-    virtual ~basic_iostream();
-
-    // assign/swap
-    basic_iostream& operator=(basic_iostream&& rhs);
-    void swap(basic_iostream& rhs);
-};
-
-template <class charT, class traits>
-  void
-  swap(basic_iostream<charT, traits>& x, basic_iostream<charT, traits>& y);
-
-typedef basic_iostream<char> iostream;
-typedef basic_iostream<wchar_t> wiostream;
-
-template <class charT, class traits>
-  basic_istream<charT,traits>&
-  ws(basic_istream<charT,traits>& is);
-
-// rvalue stream extraction
-template <class Stream, class T>
-  Stream&& operator>>(Stream&& is, T&& x);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/istream.syn.
 
 #include <__config>
 #include <__utility/forward.h>
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -10,549 +10,7 @@
 #ifndef _LIBCPP_ITERATOR
 #define _LIBCPP_ITERATOR
 
-/*
-    iterator synopsis
-
-#include <concepts>
-
-namespace std
-{
-template<class> struct incrementable_traits;       // since C++20
-template<class T>
-  using iter_difference_t = see below;             // since C++20
-
-template<class> struct indirectly_readable_traits; // since C++20
-template<class T>
-  using iter_value_t = see below;                  // since C++20
-
-template<class Iterator>
-struct iterator_traits;
-
-template<class T>
-  requires is_object_v<T>                    // since C++20
-struct iterator_traits<T*>;
-
-template<dereferenceable T>
-  using iter_reference_t = decltype(*declval<T&>());
-
-namespace ranges::inline unspecified {
-    inline constexpr unspecified iter_move = unspecified; // since C++20, nodiscard as an extension
-}}
-
-template<dereferenceable T>
-  requires ...
-using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<T&>())); // since C++20
-
-// [iterator.concepts], iterator concepts
-// [iterator.concept.readable], concept indirectly_readable
-template<class In>
-  concept indirectly_readable = see below;                      // since C++20
-
-template<indirectly_readable T>
-  using iter_common_reference_t =
-    common_reference_t<iter_reference_t<T>, iter_value_t<T>&>;  // since C++20
-
-// [iterator.concept.writable], concept indirectly_writable
-template<class Out, class T>
-  concept indirectly_writable = see below;                // since C++20
-
-// [iterator.concept.winc], concept weakly_incrementable
-template<class I>
-  concept weakly_incrementable = see below;                // since C++20
-
-// [iterator.concept.inc], concept incrementable
-template<class I>
-  concept incrementable = see below;                       // since C++20
-
-// [iterator.concept.iterator], concept input_or_output_iterator
-  template<class I>
-    concept input_or_output_iterator = see below;          // since C++20
-
-// [iterator.concept.sentinel], concept sentinel_for
-template<class S, class I>
-  concept sentinel_for = see below;                        // since C++20
-
-// [iterator.concept.sizedsentinel], concept sized_sentinel_for
-template<class S, class I>
-  inline constexpr bool disable_sized_sentinel_for = false;
-
-template<class S, class I>
-  concept sized_sentinel_for = see below;
-
-// [iterator.concept.input], concept input_iterator
-template<class I>
-  concept input_iterator = see below;                      // since C++20
-
-// [iterator.concept.forward], concept forward_iterator
-template<class I>
-  concept forward_iterator = see below;                    // since C++20
-
-// [iterator.concept.bidir], concept bidirectional_iterator
-template<class I>
-  concept bidirectional_iterator = see below;              // since C++20
-
-// [iterator.concept.random.access], concept random_access_iterator
-template<class I>
-  concept random_access_iterator = see below;              // since C++20
-
-// [indirectcallable]
-// [indirectcallable.indirectinvocable]
-template<class F, class I>
-  concept indirectly_unary_invocable = see below;          // since C++20
-
-template<class F, class I>
-  concept indirectly_regular_unary_invocable = see below;  // since C++20
-
-template<class F, class I>
-  concept indirect_unary_predicate = see below;            // since C++20
-
-template<class F, class I1, class I2>
-  concept indirect_binary_predicate = see below;           // since C++20
-
-template<class F, class I1, class I2 = I1>
-  concept indirect_equivalence_relation = see below;       // since C++20
-
-template<class F, class I1, class I2 = I1>
-  concept indirect_strict_weak_order = see below;          // since C++20
-
-template<class F, class... Is>
-  using indirect_result_t = see below;                     // since C++20
-
-// [projected], projected
-template<indirectly_readable I, indirectly_regular_unary_invocable<I> Proj>
-  struct projected;                                        // since C++20
-
-template<weakly_incrementable I, indirectly_regular_unary_invocable<I> Proj>
-  struct incrementable_traits<projected<I, Proj>>;         // since C++20
-
-// [alg.req.ind.move], concept indirectly_movable
-template<class In, class Out>
-  concept indirectly_movable = see below;                  // since C++20
-
-template<class In, class Out>
-  concept indirectly_movable_storable = see below;         // since C++20
-
-template<class Category, class T, class Distance = ptrdiff_t,
-         class Pointer = T*, class Reference = T&>
-struct iterator                                            // deprecated in C++17
-{
-    typedef T         value_type;
-    typedef Distance  difference_type;
-    typedef Pointer   pointer;
-    typedef Reference reference;
-    typedef Category  iterator_category;
-};
-
-struct input_iterator_tag  {};
-struct output_iterator_tag {};
-struct forward_iterator_tag       : public input_iterator_tag         {};
-struct bidirectional_iterator_tag : public forward_iterator_tag       {};
-struct random_access_iterator_tag : public bidirectional_iterator_tag {};
-
-// 27.4.3, iterator operations
-template <class InputIterator, class Distance>  // constexpr in C++17
-  constexpr void advance(InputIterator& i, Distance n);
-
-template <class InputIterator>  // constexpr in C++17
-  constexpr typename iterator_traits<InputIterator>::difference_type
-    distance(InputIterator first, InputIterator last);
-
-template <class InputIterator>  // constexpr in C++17
-  constexpr InputIterator next(InputIterator x,
-typename iterator_traits<InputIterator>::difference_type n = 1);
-
-template <class BidirectionalIterator>  // constexpr in C++17
-  constexpr BidirectionalIterator prev(BidirectionalIterator x,
-    typename iterator_traits<BidirectionalIterator>::difference_type n = 1);
-
-// [range.iter.ops], range iterator operations
-namespace ranges {
-  // [range.iter.op.advance], ranges::advance
-  template<input_or_output_iterator I>
-    constexpr void advance(I& i, iter_difference_t<I> n);                          // since C++20
-  template<input_or_output_iterator I, sentinel_for<I> S>
-    constexpr void advance(I& i, S bound);                                         // since C++20
-  template<input_or_output_iterator I, sentinel_for<I> S>
-    constexpr iter_difference_t<I> advance(I& i, iter_difference_t<I> n, S bound); // since C++20
-}
-
-template <class Iterator>
-class reverse_iterator
-    : public iterator<typename iterator_traits<Iterator>::iterator_category, // until C++17
-                      typename iterator_traits<Iterator>::value_type,
-                      typename iterator_traits<Iterator>::difference_type,
-                      typename iterator_traits<Iterator>::pointer,
-                      typename iterator_traits<Iterator>::reference>
-{
-protected:
-    Iterator current;
-public:
-    typedef Iterator                                            iterator_type;
-    typedef typename iterator_traits<Iterator>::difference_type difference_type;
-    typedef typename iterator_traits<Iterator>::reference       reference;
-    typedef typename iterator_traits<Iterator>::pointer         pointer;
-
-    constexpr reverse_iterator();
-    constexpr explicit reverse_iterator(Iterator x);
-    template <class U> constexpr reverse_iterator(const reverse_iterator<U>& u);
-    template <class U> constexpr reverse_iterator& operator=(const reverse_iterator<U>& u);
-    constexpr Iterator base() const;
-    constexpr reference operator*() const;
-    constexpr pointer   operator->() const;
-    constexpr reverse_iterator& operator++();
-    constexpr reverse_iterator  operator++(int);
-    constexpr reverse_iterator& operator--();
-    constexpr reverse_iterator  operator--(int);
-    constexpr reverse_iterator  operator+ (difference_type n) const;
-    constexpr reverse_iterator& operator+=(difference_type n);
-    constexpr reverse_iterator  operator- (difference_type n) const;
-    constexpr reverse_iterator& operator-=(difference_type n);
-    constexpr reference         operator[](difference_type n) const;
-};
-
-template <class Iterator1, class Iterator2>
-constexpr bool                          // constexpr in C++17
-operator==(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool                          // constexpr in C++17
-operator<(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool                          // constexpr in C++17
-operator!=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool                          // constexpr in C++17
-operator>(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool                          // constexpr in C++17
-operator>=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool                          // constexpr in C++17
-operator<=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr auto
-operator-(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y)
--> decltype(__y.base() - __x.base());   // constexpr in C++17
-
-template <class Iterator>
-constexpr reverse_iterator<Iterator>
-operator+(typename reverse_iterator<Iterator>::difference_type n,
-          const reverse_iterator<Iterator>& x);   // constexpr in C++17
-
-template <class Iterator>
-constexpr reverse_iterator<Iterator> make_reverse_iterator(Iterator i); // C++14, constexpr in C++17
-
-template <class Container>
-class back_insert_iterator
-    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
-{
-protected:
-    Container* container;
-public:
-    typedef Container                   container_type;
-    typedef void                        value_type;
-    typedef void                        difference_type; // until C++20
-    typedef ptrdiff_t                   difference_type; // since C++20
-    typedef void                        reference;
-    typedef void                        pointer;
-
-    explicit back_insert_iterator(Container& x);  // constexpr in C++20
-    back_insert_iterator& operator=(const typename Container::value_type& value);  // constexpr in C++20
-    back_insert_iterator& operator*();  // constexpr in C++20
-    back_insert_iterator& operator++();  // constexpr in C++20
-    back_insert_iterator  operator++(int);  // constexpr in C++20
-};
-
-template <class Container> back_insert_iterator<Container> back_inserter(Container& x);  // constexpr in C++20
-
-template <class Container>
-class front_insert_iterator
-    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
-{
-protected:
-    Container* container;
-public:
-    typedef Container                    container_type;
-    typedef void                         value_type;
-    typedef void                         difference_type; // until C++20
-    typedef ptrdiff_t                    difference_type; // since C++20
-    typedef void                         reference;
-    typedef void                         pointer;
-
-    explicit front_insert_iterator(Container& x);  // constexpr in C++20
-    front_insert_iterator& operator=(const typename Container::value_type& value);  // constexpr in C++20
-    front_insert_iterator& operator*();  // constexpr in C++20
-    front_insert_iterator& operator++();  // constexpr in C++20
-    front_insert_iterator  operator++(int);  // constexpr in C++20
-};
-
-template <class Container> front_insert_iterator<Container> front_inserter(Container& x);  // constexpr in C++20
-
-template <class Container>
-class insert_iterator
-    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
-{
-protected:
-    Container* container;
-    typename Container::iterator iter;
-public:
-    typedef Container              container_type;
-    typedef void                   value_type;
-    typedef void                   difference_type; // until C++20
-    typedef ptrdiff_t              difference_type; // since C++20
-    typedef void                   reference;
-    typedef void                   pointer;
-
-    insert_iterator(Container& x, typename Container::iterator i);  // constexpr in C++20
-    insert_iterator& operator=(const typename Container::value_type& value);  // constexpr in C++20
-    insert_iterator& operator*();  // constexpr in C++20
-    insert_iterator& operator++();  // constexpr in C++20
-    insert_iterator& operator++(int);  // constexpr in C++20
-};
-
-template <class Container, class Iterator>
-insert_iterator<Container> inserter(Container& x, Iterator i);  // constexpr in C++20
-
-template <class Iterator>
-class move_iterator {
-public:
-    typedef Iterator                                              iterator_type;
-    typedef typename iterator_traits<Iterator>::difference_type   difference_type;
-    typedef Iterator                                              pointer;
-    typedef typename iterator_traits<Iterator>::value_type        value_type;
-    typedef typename iterator_traits<Iterator>::iterator_category iterator_category;
-    typedef value_type&&                                          reference;
-
-    constexpr move_iterator();  // all the constexprs are in C++17
-    constexpr explicit move_iterator(Iterator i);
-    template <class U>
-      constexpr move_iterator(const move_iterator<U>& u);
-    template <class U>
-      constexpr move_iterator& operator=(const move_iterator<U>& u);
-    constexpr iterator_type base() const;
-    constexpr reference operator*() const;
-    constexpr pointer operator->() const;
-    constexpr move_iterator& operator++();
-    constexpr move_iterator operator++(int);
-    constexpr move_iterator& operator--();
-    constexpr move_iterator operator--(int);
-    constexpr move_iterator operator+(difference_type n) const;
-    constexpr move_iterator& operator+=(difference_type n);
-    constexpr move_iterator operator-(difference_type n) const;
-    constexpr move_iterator& operator-=(difference_type n);
-    constexpr unspecified operator[](difference_type n) const;
-private:
-    Iterator current; // exposition only
-};
-
-template <class Iterator1, class Iterator2>
-constexpr bool   // constexpr in C++17
-operator==(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool   // constexpr in C++17
-operator!=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool   // constexpr in C++17
-operator<(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool   // constexpr in C++17
-operator<=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool   // constexpr in C++17
-operator>(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr bool   // constexpr in C++17
-operator>=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
-
-template <class Iterator1, class Iterator2>
-constexpr auto   // constexpr in C++17
-operator-(const move_iterator<Iterator1>& x,
-          const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
-
-template <class Iterator>
-constexpr move_iterator<Iterator> operator+(   // constexpr in C++17
-            typename move_iterator<Iterator>::difference_type n,
-            const move_iterator<Iterator>& x);
-
-template <class Iterator>   // constexpr in C++17
-constexpr  move_iterator<Iterator> make_move_iterator(const Iterator& i);
-
-// [default.sentinel], default sentinel
-struct default_sentinel_t;
-inline constexpr default_sentinel_t default_sentinel{};
-
-template <class T, class charT = char, class traits = char_traits<charT>, class Distance = ptrdiff_t>
-class istream_iterator
-    : public iterator<input_iterator_tag, T, Distance, const T*, const T&> // until C++17
-{
-public:
-    typedef input_iterator_tag           iterator_category;
-    typedef T                            value_type;
-    typedef Distance                     difference_type;
-    typedef const T*                     pointer;
-    typedef const T&                     reference;
-
-    typedef charT                        char_type;
-    typedef traits                       traits_type;
-    typedef basic_istream<charT, traits> istream_type;
-
-    constexpr istream_iterator();
-    istream_iterator(istream_type& s);
-    istream_iterator(const istream_iterator& x);
-    ~istream_iterator();
-
-    const T& operator*() const;
-    const T* operator->() const;
-    istream_iterator& operator++();
-    istream_iterator  operator++(int);
-};
-
-template <class T, class charT, class traits, class Distance>
-bool operator==(const istream_iterator<T,charT,traits,Distance>& x,
-                const istream_iterator<T,charT,traits,Distance>& y);
-template <class T, class charT, class traits, class Distance>
-bool operator!=(const istream_iterator<T,charT,traits,Distance>& x,
-                const istream_iterator<T,charT,traits,Distance>& y);
-
-template <class T, class charT = char, class traits = char_traits<charT> >
-class ostream_iterator
-    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
-{
-public:
-    typedef output_iterator_tag         iterator_category;
-    typedef void                        value_type;
-    typedef void                        difference_type; // until C++20
-    typedef ptrdiff_t                   difference_type; // since C++20
-    typedef void                        pointer;
-    typedef void                        reference;
-
-    typedef charT char_type;
-    typedef traits traits_type;
-    typedef basic_ostream<charT,traits> ostream_type;
-
-    ostream_iterator(ostream_type& s);
-    ostream_iterator(ostream_type& s, const charT* delimiter);
-    ostream_iterator(const ostream_iterator& x);
-    ~ostream_iterator();
-    ostream_iterator& operator=(const T& value);
-
-    ostream_iterator& operator*();
-    ostream_iterator& operator++();
-    ostream_iterator& operator++(int);
-};
-
-template<class charT, class traits = char_traits<charT> >
-class istreambuf_iterator
-    : public iterator<input_iterator_tag, charT, traits::off_type, unspecified, charT> // until C++17
-{
-public:
-    typedef input_iterator_tag              iterator_category;
-    typedef charT                           value_type;
-    typedef traits::off_type                difference_type;
-    typedef unspecified                     pointer;
-    typedef charT                           reference;
-
-    typedef charT                           char_type;
-    typedef traits                          traits_type;
-    typedef traits::int_type                int_type;
-    typedef basic_streambuf<charT, traits>  streambuf_type;
-    typedef basic_istream<charT, traits>    istream_type;
-
-    istreambuf_iterator() noexcept;
-    istreambuf_iterator(istream_type& s) noexcept;
-    istreambuf_iterator(streambuf_type* s) noexcept;
-    istreambuf_iterator(a-private-type) noexcept;
-
-    charT                operator*() const;
-    pointer operator->() const;
-    istreambuf_iterator& operator++();
-    a-private-type       operator++(int);
-
-    bool equal(const istreambuf_iterator& b) const;
-};
-
-template <class charT, class traits>
-bool operator==(const istreambuf_iterator<charT,traits>& a,
-                const istreambuf_iterator<charT,traits>& b);
-template <class charT, class traits>
-bool operator!=(const istreambuf_iterator<charT,traits>& a,
-                const istreambuf_iterator<charT,traits>& b);
-
-template <class charT, class traits = char_traits<charT> >
-class ostreambuf_iterator
-    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
-{
-public:
-    typedef output_iterator_tag            iterator_category;
-    typedef void                           value_type;
-    typedef void                           difference_type; // until C++20
-    typedef ptrdiff_t                      difference_type; // since C++20
-    typedef void                           pointer;
-    typedef void                           reference;
-
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef basic_streambuf<charT, traits> streambuf_type;
-    typedef basic_ostream<charT, traits>   ostream_type;
-
-    ostreambuf_iterator(ostream_type& s) noexcept;
-    ostreambuf_iterator(streambuf_type* s) noexcept;
-    ostreambuf_iterator& operator=(charT c);
-    ostreambuf_iterator& operator*();
-    ostreambuf_iterator& operator++();
-    ostreambuf_iterator& operator++(int);
-    bool failed() const noexcept;
-};
-
-template <class C> constexpr auto begin(C& c) -> decltype(c.begin());
-template <class C> constexpr auto begin(const C& c) -> decltype(c.begin());
-template <class C> constexpr auto end(C& c) -> decltype(c.end());
-template <class C> constexpr auto end(const C& c) -> decltype(c.end());
-template <class T, size_t N> constexpr T* begin(T (&array)[N]);
-template <class T, size_t N> constexpr T* end(T (&array)[N]);
-
-template <class C> auto constexpr cbegin(const C& c) -> decltype(std::begin(c));        // C++14
-template <class C> auto constexpr cend(const C& c) -> decltype(std::end(c));            // C++14
-template <class C> auto constexpr rbegin(C& c) -> decltype(c.rbegin());                 // C++14
-template <class C> auto constexpr rbegin(const C& c) -> decltype(c.rbegin());           // C++14
-template <class C> auto constexpr rend(C& c) -> decltype(c.rend());                     // C++14
-template <class C> constexpr auto rend(const C& c) -> decltype(c.rend());               // C++14
-template <class E> reverse_iterator<const E*> constexpr rbegin(initializer_list<E> il); // C++14
-template <class E> reverse_iterator<const E*> constexpr rend(initializer_list<E> il);   // C++14
-template <class T, size_t N> reverse_iterator<T*> constexpr rbegin(T (&array)[N]);      // C++14
-template <class T, size_t N> reverse_iterator<T*> constexpr rend(T (&array)[N]);        // C++14
-template <class C> constexpr auto crbegin(const C& c) -> decltype(std::rbegin(c));      // C++14
-template <class C> constexpr auto crend(const C& c) -> decltype(std::rend(c));          // C++14
-
-// 24.8, container access:
-template <class C> constexpr auto size(const C& c) -> decltype(c.size());         // C++17
-template <class T, size_t N> constexpr size_t size(const T (&array)[N]) noexcept; // C++17
-
-template <class C> constexpr auto ssize(const C& c)
-    -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>;                    // C++20
-template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20
-
-template <class C> constexpr auto empty(const C& c) -> decltype(c.empty());       // C++17
-template <class T, size_t N> constexpr bool empty(const T (&array)[N]) noexcept;  // C++17
-template <class E> constexpr bool empty(initializer_list<E> il) noexcept;         // C++17
-template <class C> constexpr auto data(C& c) -> decltype(c.data());               // C++17
-template <class C> constexpr auto data(const C& c) -> decltype(c.data());         // C++17
-template <class T, size_t N> constexpr T* data(T (&array)[N]) noexcept;           // C++17
-template <class E> constexpr const E* data(initializer_list<E> il) noexcept;      // C++17
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/iterator.synopsis.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/latch b/libcxx/include/latch
--- a/libcxx/include/latch
+++ b/libcxx/include/latch
@@ -10,35 +10,7 @@
 #ifndef _LIBCPP_LATCH
 #define _LIBCPP_LATCH
 
-/*
-    latch synopsis
-
-namespace std
-{
-
-  class latch
-  {
-  public:
-    static constexpr ptrdiff_t max() noexcept;
-
-    constexpr explicit latch(ptrdiff_t __expected);
-    ~latch();
-
-    latch(const latch&) = delete;
-    latch& operator=(const latch&) = delete;
-
-    void count_down(ptrdiff_t __update = 1);
-    bool try_wait() const noexcept;
-    void wait() const;
-    void arrive_and_wait(ptrdiff_t __update = 1);
-
-  private:
-    ptrdiff_t __counter; // exposition only
-  };
-
-}
-
-*/
+// Synopsis avaiable at http://wg21.link/latch.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/limits b/libcxx/include/limits
--- a/libcxx/include/limits
+++ b/libcxx/include/limits
@@ -10,97 +10,8 @@
 #ifndef _LIBCPP_LIMITS
 #define _LIBCPP_LIMITS
 
-/*
-    limits synopsis
+// Synopsis avaiable at http://wg21.link/limits.syn.
 
-namespace std
-{
-
-template<class T>
-class numeric_limits
-{
-public:
-    static constexpr bool is_specialized = false;
-    static constexpr T min() noexcept;
-    static constexpr T max() noexcept;
-    static constexpr T lowest() noexcept;
-
-    static constexpr int  digits = 0;
-    static constexpr int  digits10 = 0;
-    static constexpr int  max_digits10 = 0;
-    static constexpr bool is_signed = false;
-    static constexpr bool is_integer = false;
-    static constexpr bool is_exact = false;
-    static constexpr int  radix = 0;
-    static constexpr T epsilon() noexcept;
-    static constexpr T round_error() noexcept;
-
-    static constexpr int  min_exponent = 0;
-    static constexpr int  min_exponent10 = 0;
-    static constexpr int  max_exponent = 0;
-    static constexpr int  max_exponent10 = 0;
-
-    static constexpr bool has_infinity = false;
-    static constexpr bool has_quiet_NaN = false;
-    static constexpr bool has_signaling_NaN = false;
-    static constexpr float_denorm_style has_denorm = denorm_absent;
-    static constexpr bool has_denorm_loss = false;
-    static constexpr T infinity() noexcept;
-    static constexpr T quiet_NaN() noexcept;
-    static constexpr T signaling_NaN() noexcept;
-    static constexpr T denorm_min() noexcept;
-
-    static constexpr bool is_iec559 = false;
-    static constexpr bool is_bounded = false;
-    static constexpr bool is_modulo = false;
-
-    static constexpr bool traps = false;
-    static constexpr bool tinyness_before = false;
-    static constexpr float_round_style round_style = round_toward_zero;
-};
-
-enum float_round_style
-{
-    round_indeterminate       = -1,
-    round_toward_zero         =  0,
-    round_to_nearest          =  1,
-    round_toward_infinity     =  2,
-    round_toward_neg_infinity =  3
-};
-
-enum float_denorm_style
-{
-    denorm_indeterminate = -1,
-    denorm_absent = 0,
-    denorm_present = 1
-};
-
-template<> class numeric_limits<cv bool>;
-
-template<> class numeric_limits<cv char>;
-template<> class numeric_limits<cv signed char>;
-template<> class numeric_limits<cv unsigned char>;
-template<> class numeric_limits<cv wchar_t>;
-template<> class numeric_limits<cv char8_t>; // C++20
-template<> class numeric_limits<cv char16_t>;
-template<> class numeric_limits<cv char32_t>;
-
-template<> class numeric_limits<cv short>;
-template<> class numeric_limits<cv int>;
-template<> class numeric_limits<cv long>;
-template<> class numeric_limits<cv long long>;
-template<> class numeric_limits<cv unsigned short>;
-template<> class numeric_limits<cv unsigned int>;
-template<> class numeric_limits<cv unsigned long>;
-template<> class numeric_limits<cv unsigned long long>;
-
-template<> class numeric_limits<cv float>;
-template<> class numeric_limits<cv double>;
-template<> class numeric_limits<cv long double>;
-
-}  // std
-
-*/
 #include <__config>
 #include <type_traits>
 
diff --git a/libcxx/include/list b/libcxx/include/list
--- a/libcxx/include/list
+++ b/libcxx/include/list
@@ -10,175 +10,7 @@
 #ifndef _LIBCPP_LIST
 #define _LIBCPP_LIST
 
-/*
-    list synopsis
-
-namespace std
-{
-
-template <class T, class Alloc = allocator<T> >
-class list
-{
-public:
-
-    // types:
-    typedef T value_type;
-    typedef Alloc allocator_type;
-    typedef typename allocator_type::reference reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef typename allocator_type::pointer pointer;
-    typedef typename allocator_type::const_pointer const_pointer;
-    typedef implementation-defined iterator;
-    typedef implementation-defined const_iterator;
-    typedef implementation-defined size_type;
-    typedef implementation-defined difference_type;
-    typedef reverse_iterator<iterator> reverse_iterator;
-    typedef reverse_iterator<const_iterator> const_reverse_iterator;
-
-    list()
-        noexcept(is_nothrow_default_constructible<allocator_type>::value);
-    explicit list(const allocator_type& a);
-    explicit list(size_type n);
-    explicit list(size_type n, const allocator_type& a); // C++14
-    list(size_type n, const value_type& value);
-    list(size_type n, const value_type& value, const allocator_type& a);
-    template <class Iter>
-        list(Iter first, Iter last);
-    template <class Iter>
-        list(Iter first, Iter last, const allocator_type& a);
-    list(const list& x);
-    list(const list&, const allocator_type& a);
-    list(list&& x)
-        noexcept(is_nothrow_move_constructible<allocator_type>::value);
-    list(list&&, const allocator_type& a);
-    list(initializer_list<value_type>);
-    list(initializer_list<value_type>, const allocator_type& a);
-
-    ~list();
-
-    list& operator=(const list& x);
-    list& operator=(list&& x)
-        noexcept(
-             allocator_type::propagate_on_container_move_assignment::value &&
-             is_nothrow_move_assignable<allocator_type>::value);
-    list& operator=(initializer_list<value_type>);
-    template <class Iter>
-        void assign(Iter first, Iter last);
-    void assign(size_type n, const value_type& t);
-    void assign(initializer_list<value_type>);
-
-    allocator_type get_allocator() const noexcept;
-
-    iterator begin() noexcept;
-    const_iterator begin() const noexcept;
-    iterator end() noexcept;
-    const_iterator end() const noexcept;
-    reverse_iterator rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-    reverse_iterator rend() noexcept;
-    const_reverse_iterator rend() const noexcept;
-    const_iterator cbegin() const noexcept;
-    const_iterator cend() const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend() const noexcept;
-
-    reference front();
-    const_reference front() const;
-    reference back();
-    const_reference back() const;
-
-    bool empty() const noexcept;
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-
-    template <class... Args>
-        reference emplace_front(Args&&... args); // reference in C++17
-    void pop_front();
-    template <class... Args>
-        reference emplace_back(Args&&... args);  // reference in C++17
-    void pop_back();
-    void push_front(const value_type& x);
-    void push_front(value_type&& x);
-    void push_back(const value_type& x);
-    void push_back(value_type&& x);
-    template <class... Args>
-        iterator emplace(const_iterator position, Args&&... args);
-    iterator insert(const_iterator position, const value_type& x);
-    iterator insert(const_iterator position, value_type&& x);
-    iterator insert(const_iterator position, size_type n, const value_type& x);
-    template <class Iter>
-        iterator insert(const_iterator position, Iter first, Iter last);
-    iterator insert(const_iterator position, initializer_list<value_type> il);
-
-    iterator erase(const_iterator position);
-    iterator erase(const_iterator position, const_iterator last);
-
-    void resize(size_type sz);
-    void resize(size_type sz, const value_type& c);
-
-    void swap(list&)
-        noexcept(allocator_traits<allocator_type>::is_always_equal::value);  // C++17
-    void clear() noexcept;
-
-    void splice(const_iterator position, list& x);
-    void splice(const_iterator position, list&& x);
-    void splice(const_iterator position, list& x, const_iterator i);
-    void splice(const_iterator position, list&& x, const_iterator i);
-    void splice(const_iterator position, list& x, const_iterator first,
-                                                  const_iterator last);
-    void splice(const_iterator position, list&& x, const_iterator first,
-                                                  const_iterator last);
-
-    size_type remove(const value_type& value);       // void before C++20
-    template <class Pred>
-      size_type remove_if(Pred pred);                // void before C++20
-    size_type unique();                              // void before C++20
-    template <class BinaryPredicate>
-      size_type unique(BinaryPredicate binary_pred); // void before C++20
-    void merge(list& x);
-    void merge(list&& x);
-    template <class Compare>
-        void merge(list& x, Compare comp);
-    template <class Compare>
-        void merge(list&& x, Compare comp);
-    void sort();
-    template <class Compare>
-        void sort(Compare comp);
-    void reverse() noexcept;
-};
-
-
-template <class InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-    list(InputIterator, InputIterator, Allocator = Allocator())
-    -> list<typename iterator_traits<InputIterator>::value_type, Allocator>;  // C++17
-
-template <class T, class Alloc>
-    bool operator==(const list<T,Alloc>& x, const list<T,Alloc>& y);
-template <class T, class Alloc>
-    bool operator< (const list<T,Alloc>& x, const list<T,Alloc>& y);
-template <class T, class Alloc>
-    bool operator!=(const list<T,Alloc>& x, const list<T,Alloc>& y);
-template <class T, class Alloc>
-    bool operator> (const list<T,Alloc>& x, const list<T,Alloc>& y);
-template <class T, class Alloc>
-    bool operator>=(const list<T,Alloc>& x, const list<T,Alloc>& y);
-template <class T, class Alloc>
-    bool operator<=(const list<T,Alloc>& x, const list<T,Alloc>& y);
-
-template <class T, class Alloc>
-    void swap(list<T,Alloc>& x, list<T,Alloc>& y)
-         noexcept(noexcept(x.swap(y)));
-
-template <class T, class Allocator, class U>
-    typename list<T, Allocator>::size_type
-    erase(list<T, Allocator>& c, const U& value);       // C++20
-template <class T, class Allocator, class Predicate>
-    typename list<T, Allocator>::size_type
-    erase_if(list<T, Allocator>& c, Predicate pred);    // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/list.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/locale b/libcxx/include/locale
--- a/libcxx/include/locale
+++ b/libcxx/include/locale
@@ -10,182 +10,7 @@
 #ifndef _LIBCPP_LOCALE
 #define _LIBCPP_LOCALE
 
-/*
-    locale synopsis
-
-namespace std
-{
-
-class locale
-{
-public:
-    // types:
-    class facet;
-    class id;
-
-    typedef int category;
-    static const category // values assigned here are for exposition only
-        none     = 0x000,
-        collate  = 0x010,
-        ctype    = 0x020,
-        monetary = 0x040,
-        numeric  = 0x080,
-        time     = 0x100,
-        messages = 0x200,
-        all = collate | ctype | monetary | numeric | time | messages;
-
-    // construct/copy/destroy:
-    locale() noexcept;
-    locale(const locale& other) noexcept;
-    explicit locale(const char* std_name);
-    explicit locale(const string& std_name);
-    locale(const locale& other, const char* std_name, category);
-    locale(const locale& other, const string& std_name, category);
-    template <class Facet> locale(const locale& other, Facet* f);
-    locale(const locale& other, const locale& one, category);
-
-    ~locale(); // not virtual
-
-    const locale& operator=(const locale& other) noexcept;
-
-    template <class Facet> locale combine(const locale& other) const;
-
-    // locale operations:
-    basic_string<char> name() const;
-    bool operator==(const locale& other) const;
-    bool operator!=(const locale& other) const;
-    template <class charT, class Traits, class Allocator>
-      bool operator()(const basic_string<charT,Traits,Allocator>& s1,
-                      const basic_string<charT,Traits,Allocator>& s2) const;
-
-    // global locale objects:
-    static locale global(const locale&);
-    static const locale& classic();
-};
-
-template <class Facet> const Facet& use_facet(const locale&);
-template <class Facet> bool has_facet(const locale&) noexcept;
-
-// 22.3.3, convenience interfaces:
-template <class charT> bool isspace (charT c, const locale& loc);
-template <class charT> bool isprint (charT c, const locale& loc);
-template <class charT> bool iscntrl (charT c, const locale& loc);
-template <class charT> bool isupper (charT c, const locale& loc);
-template <class charT> bool islower (charT c, const locale& loc);
-template <class charT> bool isalpha (charT c, const locale& loc);
-template <class charT> bool isdigit (charT c, const locale& loc);
-template <class charT> bool ispunct (charT c, const locale& loc);
-template <class charT> bool isxdigit(charT c, const locale& loc);
-template <class charT> bool isalnum (charT c, const locale& loc);
-template <class charT> bool isgraph (charT c, const locale& loc);
-template <class charT> charT toupper(charT c, const locale& loc);
-template <class charT> charT tolower(charT c, const locale& loc);
-
-template<class Codecvt, class Elem = wchar_t,
-         class Wide_alloc = allocator<Elem>,
-         class Byte_alloc = allocator<char>>
-class wstring_convert
-{
-public:
-    typedef basic_string<char, char_traits<char>, Byte_alloc> byte_string;
-    typedef basic_string<Elem, char_traits<Elem>, Wide_alloc> wide_string;
-    typedef typename Codecvt::state_type                      state_type;
-    typedef typename wide_string::traits_type::int_type       int_type;
-
-    wstring_convert(Codecvt* pcvt = new Codecvt);          // before C++14
-    explicit wstring_convert(Codecvt* pcvt = new Codecvt); // before C++20
-    wstring_convert() : wstring_convert(new Codecvt) {}    // C++20
-    explicit wstring_convert(Codecvt* pcvt);               // C++20
-
-    wstring_convert(Codecvt* pcvt, state_type state);
-    explicit wstring_convert(const byte_string& byte_err,           // explicit in C++14
-                    const wide_string& wide_err = wide_string());
-    wstring_convert(const wstring_convert&) = delete;               // C++14
-    wstring_convert & operator=(const wstring_convert &) = delete;  // C++14
-    ~wstring_convert();
-
-    wide_string from_bytes(char byte);
-    wide_string from_bytes(const char* ptr);
-    wide_string from_bytes(const byte_string& str);
-    wide_string from_bytes(const char* first, const char* last);
-
-    byte_string to_bytes(Elem wchar);
-    byte_string to_bytes(const Elem* wptr);
-    byte_string to_bytes(const wide_string& wstr);
-    byte_string to_bytes(const Elem* first, const Elem* last);
-
-    size_t converted() const; // noexcept in C++14
-    state_type state() const;
-};
-
-template <class Codecvt, class Elem = wchar_t, class Tr = char_traits<Elem>>
-class wbuffer_convert
-    : public basic_streambuf<Elem, Tr>
-{
-public:
-    typedef typename Tr::state_type state_type;
-
-    wbuffer_convert(streambuf* bytebuf = 0, Codecvt* pcvt = new Codecvt,
-                    state_type state = state_type());          // before C++14
-    explicit wbuffer_convert(streambuf* bytebuf = nullptr, Codecvt* pcvt = new Codecvt,
-                            state_type state = state_type()); // before C++20
-    wbuffer_convert() : wbuffer_convert(nullptr) {} // C++20
-    explicit wbuffer_convert(streambuf* bytebuf, Codecvt* pcvt = new Codecvt,
-                            state_type state = state_type()); // C++20
-
-    wbuffer_convert(const wbuffer_convert&) = delete;               // C++14
-    wbuffer_convert & operator=(const wbuffer_convert &) = delete;  // C++14
-    ~wbuffer_convert();                                             // C++14
-
-    streambuf* rdbuf() const;
-    streambuf* rdbuf(streambuf* bytebuf);
-
-    state_type state() const;
-};
-
-// 22.4.1 and 22.4.1.3, ctype:
-class ctype_base;
-template <class charT> class ctype;
-template <> class ctype<char>; // specialization
-template <class charT> class ctype_byname;
-template <> class ctype_byname<char>; // specialization
-
-class codecvt_base;
-template <class internT, class externT, class stateT> class codecvt;
-template <class internT, class externT, class stateT> class codecvt_byname;
-
-// 22.4.2 and 22.4.3, numeric:
-template <class charT, class InputIterator> class num_get;
-template <class charT, class OutputIterator> class num_put;
-template <class charT> class numpunct;
-template <class charT> class numpunct_byname;
-
-// 22.4.4, col lation:
-template <class charT> class collate;
-template <class charT> class collate_byname;
-
-// 22.4.5, date and time:
-class time_base;
-template <class charT, class InputIterator> class time_get;
-template <class charT, class InputIterator> class time_get_byname;
-template <class charT, class OutputIterator> class time_put;
-template <class charT, class OutputIterator> class time_put_byname;
-
-// 22.4.6, money:
-class money_base;
-template <class charT, class InputIterator> class money_get;
-template <class charT, class OutputIterator> class money_put;
-template <class charT, bool Intl> class moneypunct;
-template <class charT, bool Intl> class moneypunct_byname;
-
-// 22.4.7, message retrieval:
-class messages_base;
-template <class charT> class messages;
-template <class charT> class messages_byname;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/locale.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/map b/libcxx/include/map
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -10,484 +10,7 @@
 #ifndef _LIBCPP_MAP
 #define _LIBCPP_MAP
 
-/*
-
-    map synopsis
-
-namespace std
-{
-
-template <class Key, class T, class Compare = less<Key>,
-          class Allocator = allocator<pair<const Key, T>>>
-class map
-{
-public:
-    // types:
-    typedef Key                                      key_type;
-    typedef T                                        mapped_type;
-    typedef pair<const key_type, mapped_type>        value_type;
-    typedef Compare                                  key_compare;
-    typedef Allocator                                allocator_type;
-    typedef typename allocator_type::reference       reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef typename allocator_type::pointer         pointer;
-    typedef typename allocator_type::const_pointer   const_pointer;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-    typedef unspecified                              node_type;              // C++17
-    typedef INSERT_RETURN_TYPE<iterator, node_type>  insert_return_type;     // C++17
-
-    class value_compare
-    {
-        friend class map;
-    protected:
-        key_compare comp;
-
-        value_compare(key_compare c);
-    public:
-        typedef bool result_type;  // deprecated in C++17, removed in C++20
-        typedef value_type first_argument_type;  // deprecated in C++17, removed in C++20
-        typedef value_type second_argument_type;  // deprecated in C++17, removed in C++20
-        bool operator()(const value_type& x, const value_type& y) const;
-    };
-
-    // construct/copy/destroy:
-    map()
-        noexcept(
-            is_nothrow_default_constructible<allocator_type>::value &&
-            is_nothrow_default_constructible<key_compare>::value &&
-            is_nothrow_copy_constructible<key_compare>::value);
-    explicit map(const key_compare& comp);
-    map(const key_compare& comp, const allocator_type& a);
-    template <class InputIterator>
-        map(InputIterator first, InputIterator last,
-            const key_compare& comp = key_compare());
-    template <class InputIterator>
-        map(InputIterator first, InputIterator last,
-            const key_compare& comp, const allocator_type& a);
-    map(const map& m);
-    map(map&& m)
-        noexcept(
-            is_nothrow_move_constructible<allocator_type>::value &&
-            is_nothrow_move_constructible<key_compare>::value);
-    explicit map(const allocator_type& a);
-    map(const map& m, const allocator_type& a);
-    map(map&& m, const allocator_type& a);
-    map(initializer_list<value_type> il, const key_compare& comp = key_compare());
-    map(initializer_list<value_type> il, const key_compare& comp, const allocator_type& a);
-    template <class InputIterator>
-        map(InputIterator first, InputIterator last, const allocator_type& a)
-            : map(first, last, Compare(), a) {}  // C++14
-    map(initializer_list<value_type> il, const allocator_type& a)
-        : map(il, Compare(), a) {}  // C++14
-   ~map();
-
-    map& operator=(const map& m);
-    map& operator=(map&& m)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<key_compare>::value);
-    map& operator=(initializer_list<value_type> il);
-
-    // iterators:
-          iterator begin() noexcept;
-    const_iterator begin() const noexcept;
-          iterator end() noexcept;
-    const_iterator end()   const noexcept;
-
-          reverse_iterator rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-          reverse_iterator rend() noexcept;
-    const_reverse_iterator rend()   const noexcept;
-
-    const_iterator         cbegin()  const noexcept;
-    const_iterator         cend()    const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend()   const noexcept;
-
-    // capacity:
-    bool      empty()    const noexcept;
-    size_type size()     const noexcept;
-    size_type max_size() const noexcept;
-
-    // element access:
-    mapped_type& operator[](const key_type& k);
-    mapped_type& operator[](key_type&& k);
-
-          mapped_type& at(const key_type& k);
-    const mapped_type& at(const key_type& k) const;
-
-    // modifiers:
-    template <class... Args>
-        pair<iterator, bool> emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    pair<iterator, bool> insert(const value_type& v);
-    pair<iterator, bool> insert(      value_type&& v);                                // C++17
-    template <class P>
-        pair<iterator, bool> insert(P&& p);
-    iterator insert(const_iterator position, const value_type& v);
-    iterator insert(const_iterator position,       value_type&& v);                   // C++17
-    template <class P>
-        iterator insert(const_iterator position, P&& p);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type> il);
-
-    node_type extract(const_iterator position);                                       // C++17
-    node_type extract(const key_type& x);                                             // C++17
-    insert_return_type insert(node_type&& nh);                                        // C++17
-    iterator insert(const_iterator hint, node_type&& nh);                             // C++17
-
-    template <class... Args>
-        pair<iterator, bool> try_emplace(const key_type& k, Args&&... args);          // C++17
-    template <class... Args>
-        pair<iterator, bool> try_emplace(key_type&& k, Args&&... args);               // C++17
-    template <class... Args>
-        iterator try_emplace(const_iterator hint, const key_type& k, Args&&... args); // C++17
-    template <class... Args>
-        iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args);      // C++17
-    template <class M>
-        pair<iterator, bool> insert_or_assign(const key_type& k, M&& obj);            // C++17
-    template <class M>
-        pair<iterator, bool> insert_or_assign(key_type&& k, M&& obj);                 // C++17
-    template <class M>
-        iterator insert_or_assign(const_iterator hint, const key_type& k, M&& obj);   // C++17
-    template <class M>
-        iterator insert_or_assign(const_iterator hint, key_type&& k, M&& obj);        // C++17
-
-    iterator  erase(const_iterator position);
-    iterator  erase(iterator position); // C++14
-    size_type erase(const key_type& k);
-    iterator  erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class C2>
-      void merge(map<Key, T, C2, Allocator>& source);         // C++17
-    template<class C2>
-      void merge(map<Key, T, C2, Allocator>&& source);        // C++17
-    template<class C2>
-      void merge(multimap<Key, T, C2, Allocator>& source);    // C++17
-    template<class C2>
-      void merge(multimap<Key, T, C2, Allocator>&& source);   // C++17
-
-    void swap(map& m)
-        noexcept(allocator_traits<allocator_type>::is_always_equal::value &&
-            is_nothrow_swappable<key_compare>::value); // C++17
-
-    // observers:
-    allocator_type get_allocator() const noexcept;
-    key_compare    key_comp()      const;
-    value_compare  value_comp()    const;
-
-    // map operations:
-          iterator find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);              // C++14
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++14
-
-    template<typename K>
-      size_type count(const K& x) const;        // C++14
-    size_type      count(const key_type& k) const;
-
-    bool           contains(const key_type& x) const;  // C++20
-    template<class K> bool contains(const K& x) const; // C++20
-
-          iterator lower_bound(const key_type& k);
-    const_iterator lower_bound(const key_type& k) const;
-    template<typename K>
-        iterator lower_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator lower_bound(const K& x) const;  // C++14
-
-          iterator upper_bound(const key_type& k);
-    const_iterator upper_bound(const key_type& k) const;
-    template<typename K>
-        iterator upper_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator upper_bound(const K& x) const;  // C++14
-
-    pair<iterator,iterator>             equal_range(const key_type& k);
-    pair<const_iterator,const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator,iterator>             equal_range(const K& x);        // C++14
-    template<typename K>
-        pair<const_iterator,const_iterator> equal_range(const K& x) const;  // C++14
-};
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator==(const map<Key, T, Compare, Allocator>& x,
-           const map<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator< (const map<Key, T, Compare, Allocator>& x,
-           const map<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator!=(const map<Key, T, Compare, Allocator>& x,
-           const map<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator> (const map<Key, T, Compare, Allocator>& x,
-           const map<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator>=(const map<Key, T, Compare, Allocator>& x,
-           const map<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator<=(const map<Key, T, Compare, Allocator>& x,
-           const map<Key, T, Compare, Allocator>& y);
-
-// specialized algorithms:
-template <class Key, class T, class Compare, class Allocator>
-void
-swap(map<Key, T, Compare, Allocator>& x, map<Key, T, Compare, Allocator>& y)
-    noexcept(noexcept(x.swap(y)));
-
-template <class Key, class T, class Compare, class Allocator, class Predicate>
-typename map<Key, T, Compare, Allocator>::size_type
-erase_if(map<Key, T, Compare, Allocator>& c, Predicate pred);  // C++20
-
-
-template <class Key, class T, class Compare = less<Key>,
-          class Allocator = allocator<pair<const Key, T>>>
-class multimap
-{
-public:
-    // types:
-    typedef Key                                      key_type;
-    typedef T                                        mapped_type;
-    typedef pair<const key_type,mapped_type>         value_type;
-    typedef Compare                                  key_compare;
-    typedef Allocator                                allocator_type;
-    typedef typename allocator_type::reference       reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-    typedef typename allocator_type::pointer         pointer;
-    typedef typename allocator_type::const_pointer   const_pointer;
-
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-    typedef unspecified                              node_type;              // C++17
-
-    class value_compare
-    {
-        friend class multimap;
-    protected:
-        key_compare comp;
-        value_compare(key_compare c);
-    public:
-        typedef bool result_type;  // deprecated in C++17, removed in C++20
-        typedef value_type first_argument_type;  // deprecated in C++17, removed in C++20
-        typedef value_type second_argument_type;  // deprecated in C++17, removed in C++20
-        bool operator()(const value_type& x, const value_type& y) const;
-    };
-
-    // construct/copy/destroy:
-    multimap()
-        noexcept(
-            is_nothrow_default_constructible<allocator_type>::value &&
-            is_nothrow_default_constructible<key_compare>::value &&
-            is_nothrow_copy_constructible<key_compare>::value);
-    explicit multimap(const key_compare& comp);
-    multimap(const key_compare& comp, const allocator_type& a);
-    template <class InputIterator>
-        multimap(InputIterator first, InputIterator last, const key_compare& comp);
-    template <class InputIterator>
-        multimap(InputIterator first, InputIterator last, const key_compare& comp,
-                 const allocator_type& a);
-    multimap(const multimap& m);
-    multimap(multimap&& m)
-        noexcept(
-            is_nothrow_move_constructible<allocator_type>::value &&
-            is_nothrow_move_constructible<key_compare>::value);
-    explicit multimap(const allocator_type& a);
-    multimap(const multimap& m, const allocator_type& a);
-    multimap(multimap&& m, const allocator_type& a);
-    multimap(initializer_list<value_type> il, const key_compare& comp = key_compare());
-    multimap(initializer_list<value_type> il, const key_compare& comp,
-             const allocator_type& a);
-    template <class InputIterator>
-        multimap(InputIterator first, InputIterator last, const allocator_type& a)
-            : multimap(first, last, Compare(), a) {} // C++14
-    multimap(initializer_list<value_type> il, const allocator_type& a)
-        : multimap(il, Compare(), a) {} // C++14
-    ~multimap();
-
-    multimap& operator=(const multimap& m);
-    multimap& operator=(multimap&& m)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<key_compare>::value);
-    multimap& operator=(initializer_list<value_type> il);
-
-    // iterators:
-          iterator begin() noexcept;
-    const_iterator begin() const noexcept;
-          iterator end() noexcept;
-    const_iterator end()   const noexcept;
-
-          reverse_iterator rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-          reverse_iterator rend() noexcept;
-    const_reverse_iterator rend()   const noexcept;
-
-    const_iterator         cbegin()  const noexcept;
-    const_iterator         cend()    const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend()   const noexcept;
-
-    // capacity:
-    bool      empty()    const noexcept;
-    size_type size()     const noexcept;
-    size_type max_size() const noexcept;
-
-    // modifiers:
-    template <class... Args>
-        iterator emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    iterator insert(const value_type& v);
-    iterator insert(      value_type&& v);                                            // C++17
-    template <class P>
-        iterator insert(P&& p);
-    iterator insert(const_iterator position, const value_type& v);
-    iterator insert(const_iterator position,       value_type&& v);                   // C++17
-    template <class P>
-        iterator insert(const_iterator position, P&& p);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type> il);
-
-    node_type extract(const_iterator position);                                       // C++17
-    node_type extract(const key_type& x);                                             // C++17
-    iterator insert(node_type&& nh);                                                  // C++17
-    iterator insert(const_iterator hint, node_type&& nh);                             // C++17
-
-    iterator  erase(const_iterator position);
-    iterator  erase(iterator position); // C++14
-    size_type erase(const key_type& k);
-    iterator  erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class C2>
-      void merge(multimap<Key, T, C2, Allocator>& source);    // C++17
-    template<class C2>
-      void merge(multimap<Key, T, C2, Allocator>&& source);   // C++17
-    template<class C2>
-      void merge(map<Key, T, C2, Allocator>& source);         // C++17
-    template<class C2>
-      void merge(map<Key, T, C2, Allocator>&& source);        // C++17
-
-    void swap(multimap& m)
-        noexcept(allocator_traits<allocator_type>::is_always_equal::value &&
-            is_nothrow_swappable<key_compare>::value); // C++17
-
-    // observers:
-    allocator_type get_allocator() const noexcept;
-    key_compare    key_comp()      const;
-    value_compare  value_comp()    const;
-
-    // map operations:
-          iterator find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);              // C++14
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++14
-
-    template<typename K>
-      size_type count(const K& x) const;        // C++14
-    size_type      count(const key_type& k) const;
-
-    bool           contains(const key_type& x) const;  // C++20
-    template<class K> bool contains(const K& x) const; // C++20
-
-          iterator lower_bound(const key_type& k);
-    const_iterator lower_bound(const key_type& k) const;
-    template<typename K>
-        iterator lower_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator lower_bound(const K& x) const;  // C++14
-
-          iterator upper_bound(const key_type& k);
-    const_iterator upper_bound(const key_type& k) const;
-    template<typename K>
-        iterator upper_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator upper_bound(const K& x) const;  // C++14
-
-    pair<iterator,iterator>             equal_range(const key_type& k);
-    pair<const_iterator,const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator,iterator>             equal_range(const K& x);        // C++14
-    template<typename K>
-        pair<const_iterator,const_iterator> equal_range(const K& x) const;  // C++14
-};
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator==(const multimap<Key, T, Compare, Allocator>& x,
-           const multimap<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator< (const multimap<Key, T, Compare, Allocator>& x,
-           const multimap<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator!=(const multimap<Key, T, Compare, Allocator>& x,
-           const multimap<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator> (const multimap<Key, T, Compare, Allocator>& x,
-           const multimap<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator>=(const multimap<Key, T, Compare, Allocator>& x,
-           const multimap<Key, T, Compare, Allocator>& y);
-
-template <class Key, class T, class Compare, class Allocator>
-bool
-operator<=(const multimap<Key, T, Compare, Allocator>& x,
-           const multimap<Key, T, Compare, Allocator>& y);
-
-// specialized algorithms:
-template <class Key, class T, class Compare, class Allocator>
-void
-swap(multimap<Key, T, Compare, Allocator>& x,
-     multimap<Key, T, Compare, Allocator>& y)
-    noexcept(noexcept(x.swap(y)));
-
-template <class Key, class T, class Compare, class Allocator, class Predicate>
-typename multimap<Key, T, Compare, Allocator>::size_type
-erase_if(multimap<Key, T, Compare, Allocator>& c, Predicate pred);  // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/associative.map.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/memory b/libcxx/include/memory
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -10,662 +10,7 @@
 #ifndef _LIBCPP_MEMORY
 #define _LIBCPP_MEMORY
 
-/*
-    memory synopsis
-
-namespace std
-{
-
-struct allocator_arg_t { };
-inline constexpr allocator_arg_t allocator_arg = allocator_arg_t();
-
-template <class T, class Alloc> struct uses_allocator;
-
-template <class Ptr>
-struct pointer_traits
-{
-    typedef Ptr pointer;
-    typedef <details> element_type;
-    typedef <details> difference_type;
-
-    template <class U> using rebind = <details>;
-
-    static pointer pointer_to(<details>);
-};
-
-template <class T>
-struct pointer_traits<T*>
-{
-    typedef T* pointer;
-    typedef T element_type;
-    typedef ptrdiff_t difference_type;
-
-    template <class U> using rebind = U*;
-
-    static pointer pointer_to(<details>) noexcept; // constexpr in C++20
-};
-
-template <class T> constexpr T* to_address(T* p) noexcept; // C++20
-template <class Ptr> constexpr auto to_address(const Ptr& p) noexcept; // C++20
-
-template <class Alloc>
-struct allocator_traits
-{
-    typedef Alloc                        allocator_type;
-    typedef typename allocator_type::value_type
-                                         value_type;
-
-    typedef Alloc::pointer | value_type* pointer;
-    typedef Alloc::const_pointer
-          | pointer_traits<pointer>::rebind<const value_type>
-                                         const_pointer;
-    typedef Alloc::void_pointer
-          | pointer_traits<pointer>::rebind<void>
-                                         void_pointer;
-    typedef Alloc::const_void_pointer
-          | pointer_traits<pointer>::rebind<const void>
-                                         const_void_pointer;
-    typedef Alloc::difference_type
-          | pointer_traits<pointer>::difference_type
-                                         difference_type;
-    typedef Alloc::size_type
-          | make_unsigned<difference_type>::type
-                                         size_type;
-    typedef Alloc::propagate_on_container_copy_assignment
-          | false_type                   propagate_on_container_copy_assignment;
-    typedef Alloc::propagate_on_container_move_assignment
-          | false_type                   propagate_on_container_move_assignment;
-    typedef Alloc::propagate_on_container_swap
-          | false_type                   propagate_on_container_swap;
-    typedef Alloc::is_always_equal
-          | is_empty                     is_always_equal;
-
-    template <class T> using rebind_alloc  = Alloc::rebind<T>::other | Alloc<T, Args...>;
-    template <class T> using rebind_traits = allocator_traits<rebind_alloc<T>>;
-
-    static pointer allocate(allocator_type& a, size_type n);                          // constexpr and [[nodiscard]] in C++20
-    static pointer allocate(allocator_type& a, size_type n, const_void_pointer hint); // constexpr and [[nodiscard]] in C++20
-
-    static void deallocate(allocator_type& a, pointer p, size_type n) noexcept; // constexpr in C++20
-
-    template <class T, class... Args>
-    static void construct(allocator_type& a, T* p, Args&&... args); // constexpr in C++20
-
-    template <class T>
-    static void destroy(allocator_type& a, T* p); // constexpr in C++20
-
-    static size_type max_size(const allocator_type& a); // noexcept in C++14, constexpr in C++20
-    static allocator_type select_on_container_copy_construction(const allocator_type& a); // constexpr in C++20
-};
-
-template <>
-class allocator<void> // removed in C++20
-{
-public:
-    typedef void*                                 pointer;
-    typedef const void*                           const_pointer;
-    typedef void                                  value_type;
-
-    template <class _Up> struct rebind {typedef allocator<_Up> other;};
-};
-
-template <class T>
-class allocator
-{
-public:
-    typedef size_t    size_type;
-    typedef ptrdiff_t difference_type;
-    typedef T*        pointer;                           // deprecated in C++17, removed in C++20
-    typedef const T*  const_pointer;                     // deprecated in C++17, removed in C++20
-    typedef typename add_lvalue_reference<T>::type
-                      reference;                         // deprecated in C++17, removed in C++20
-    typedef typename add_lvalue_reference<const T>::type
-                      const_reference;                   // deprecated in C++17, removed in C++20
-
-    typedef T         value_type;
-
-    template <class U> struct rebind {typedef allocator<U> other;}; // deprecated in C++17, removed in C++20
-
-    typedef true_type propagate_on_container_move_assignment;
-    typedef true_type is_always_equal;
-
-    constexpr allocator() noexcept;                      // constexpr in C++20
-    constexpr allocator(const allocator&) noexcept;      // constexpr in C++20
-    template <class U>
-      constexpr allocator(const allocator<U>&) noexcept; // constexpr in C++20
-    ~allocator();                                        // constexpr in C++20
-    pointer address(reference x) const noexcept;             // deprecated in C++17, removed in C++20
-    const_pointer address(const_reference x) const noexcept; // deprecated in C++17, removed in C++20
-    T* allocate(size_t n, const void* hint);          // deprecated in C++17, removed in C++20
-    T* allocate(size_t n);                              // constexpr in C++20
-    void deallocate(T* p, size_t n) noexcept;           // constexpr in C++20
-    size_type max_size() const noexcept;              // deprecated in C++17, removed in C++20
-    template<class U, class... Args>
-        void construct(U* p, Args&&... args);         // deprecated in C++17, removed in C++20
-    template <class U>
-        void destroy(U* p);                           // deprecated in C++17, removed in C++20
-};
-
-template <class T, class U>
-bool operator==(const allocator<T>&, const allocator<U>&) noexcept; // constexpr in C++20
-
-template <class T, class U>
-bool operator!=(const allocator<T>&, const allocator<U>&) noexcept; // constexpr in C++20
-
-template <class OutputIterator, class T>
-class raw_storage_iterator // deprecated in C++17, removed in C++20
-    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
-{
-public:
-    typedef output_iterator_tag iterator_category;
-    typedef void                value_type;
-    typedef void                difference_type; // until C++20
-    typedef ptrdiff_t           difference_type; // since C++20
-    typedef void                pointer;
-    typedef void                reference;
-
-    explicit raw_storage_iterator(OutputIterator x);
-    raw_storage_iterator& operator*();
-    raw_storage_iterator& operator=(const T& element);
-    raw_storage_iterator& operator++();
-    raw_storage_iterator  operator++(int);
-};
-
-template <class T> pair<T*,ptrdiff_t> get_temporary_buffer(ptrdiff_t n) noexcept;
-template <class T> void               return_temporary_buffer(T* p) noexcept;
-
-template <class T> T* addressof(T& r) noexcept;
-template <class T> T* addressof(const T&& r) noexcept = delete;
-
-template <class InputIterator, class ForwardIterator>
-ForwardIterator
-uninitialized_copy(InputIterator first, InputIterator last, ForwardIterator result);
-
-template <class InputIterator, class Size, class ForwardIterator>
-ForwardIterator
-uninitialized_copy_n(InputIterator first, Size n, ForwardIterator result);
-
-template <class ForwardIterator, class T>
-void uninitialized_fill(ForwardIterator first, ForwardIterator last, const T& x);
-
-template <class ForwardIterator, class Size, class T>
-ForwardIterator
-uninitialized_fill_n(ForwardIterator first, Size n, const T& x);
-
-template <class T, class ...Args>
-constexpr T* construct_at(T* location, Args&& ...args); // since C++20
-
-template <class T>
-void destroy_at(T* location); // constexpr in C++20
-
-template <class ForwardIterator>
-void destroy(ForwardIterator first, ForwardIterator last); // constexpr in C++20
-
-template <class ForwardIterator, class Size>
-ForwardIterator destroy_n(ForwardIterator first, Size n); // constexpr in C++20
-
-template <class InputIterator, class ForwardIterator>
- ForwardIterator uninitialized_move(InputIterator first, InputIterator last, ForwardIterator result);
-
-template <class InputIterator, class Size, class ForwardIterator>
- pair<InputIterator,ForwardIterator> uninitialized_move_n(InputIterator first, Size n, ForwardIterator result);
-
-template <class ForwardIterator>
- void uninitialized_value_construct(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class Size>
- ForwardIterator uninitialized_value_construct_n(ForwardIterator first, Size n);
-
-template <class ForwardIterator>
- void uninitialized_default_construct(ForwardIterator first, ForwardIterator last);
-
-template <class ForwardIterator, class Size>
- ForwardIterator uninitialized_default_construct_n(ForwardIterator first, Size n);
-
-template <class Y> struct auto_ptr_ref {};      // deprecated in C++11, removed in C++17
-
-template<class X>
-class auto_ptr                                  // deprecated in C++11, removed in C++17
-{
-public:
-    typedef X element_type;
-
-    explicit auto_ptr(X* p =0) throw();
-    auto_ptr(auto_ptr&) throw();
-    template<class Y> auto_ptr(auto_ptr<Y>&) throw();
-    auto_ptr& operator=(auto_ptr&) throw();
-    template<class Y> auto_ptr& operator=(auto_ptr<Y>&) throw();
-    auto_ptr& operator=(auto_ptr_ref<X> r) throw();
-    ~auto_ptr() throw();
-
-    typename add_lvalue_reference<X>::type operator*() const throw();
-    X* operator->() const throw();
-    X* get() const throw();
-    X* release() throw();
-    void reset(X* p =0) throw();
-
-    auto_ptr(auto_ptr_ref<X>) throw();
-    template<class Y> operator auto_ptr_ref<Y>() throw();
-    template<class Y> operator auto_ptr<Y>() throw();
-};
-
-template <class T>
-struct default_delete
-{
-    constexpr default_delete() noexcept = default;
-    template <class U> default_delete(const default_delete<U>&) noexcept;
-
-    void operator()(T*) const noexcept;
-};
-
-template <class T>
-struct default_delete<T[]>
-{
-    constexpr default_delete() noexcept = default;
-    void operator()(T*) const noexcept;
-    template <class U> void operator()(U*) const = delete;
-};
-
-template <class T, class D = default_delete<T>>
-class unique_ptr
-{
-public:
-    typedef see below pointer;
-    typedef T element_type;
-    typedef D deleter_type;
-
-    // constructors
-    constexpr unique_ptr() noexcept;
-    explicit unique_ptr(pointer p) noexcept;
-    unique_ptr(pointer p, see below d1) noexcept;
-    unique_ptr(pointer p, see below d2) noexcept;
-    unique_ptr(unique_ptr&& u) noexcept;
-    unique_ptr(nullptr_t) noexcept : unique_ptr() { }
-    template <class U, class E>
-        unique_ptr(unique_ptr<U, E>&& u) noexcept;
-    template <class U>
-        unique_ptr(auto_ptr<U>&& u) noexcept;       // removed in C++17
-
-    // destructor
-    ~unique_ptr();
-
-    // assignment
-    unique_ptr& operator=(unique_ptr&& u) noexcept;
-    template <class U, class E> unique_ptr& operator=(unique_ptr<U, E>&& u) noexcept;
-    unique_ptr& operator=(nullptr_t) noexcept;
-
-    // observers
-    typename add_lvalue_reference<T>::type operator*() const;
-    pointer operator->() const noexcept;
-    pointer get() const noexcept;
-    deleter_type& get_deleter() noexcept;
-    const deleter_type& get_deleter() const noexcept;
-    explicit operator bool() const noexcept;
-
-    // modifiers
-    pointer release() noexcept;
-    void reset(pointer p = pointer()) noexcept;
-    void swap(unique_ptr& u) noexcept;
-};
-
-template <class T, class D>
-class unique_ptr<T[], D>
-{
-public:
-    typedef implementation-defined pointer;
-    typedef T element_type;
-    typedef D deleter_type;
-
-    // constructors
-    constexpr unique_ptr() noexcept;
-    explicit unique_ptr(pointer p) noexcept;
-    unique_ptr(pointer p, see below d) noexcept;
-    unique_ptr(pointer p, see below d) noexcept;
-    unique_ptr(unique_ptr&& u) noexcept;
-    unique_ptr(nullptr_t) noexcept : unique_ptr() { }
-
-    // destructor
-    ~unique_ptr();
-
-    // assignment
-    unique_ptr& operator=(unique_ptr&& u) noexcept;
-    unique_ptr& operator=(nullptr_t) noexcept;
-
-    // observers
-    T& operator[](size_t i) const;
-    pointer get() const noexcept;
-    deleter_type& get_deleter() noexcept;
-    const deleter_type& get_deleter() const noexcept;
-    explicit operator bool() const noexcept;
-
-    // modifiers
-    pointer release() noexcept;
-    void reset(pointer p = pointer()) noexcept;
-    void reset(nullptr_t) noexcept;
-  template <class U> void reset(U) = delete;
-    void swap(unique_ptr& u) noexcept;
-};
-
-template <class T, class D>
-    void swap(unique_ptr<T, D>& x, unique_ptr<T, D>& y) noexcept;
-
-template <class T1, class D1, class T2, class D2>
-    bool operator==(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
-template <class T1, class D1, class T2, class D2>
-    bool operator!=(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
-template <class T1, class D1, class T2, class D2>
-    bool operator<(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
-template <class T1, class D1, class T2, class D2>
-    bool operator<=(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
-template <class T1, class D1, class T2, class D2>
-    bool operator>(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
-template <class T1, class D1, class T2, class D2>
-    bool operator>=(const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y);
-
-template <class T, class D>
-    bool operator==(const unique_ptr<T, D>& x, nullptr_t) noexcept;
-template <class T, class D>
-    bool operator==(nullptr_t, const unique_ptr<T, D>& y) noexcept;
-template <class T, class D>
-    bool operator!=(const unique_ptr<T, D>& x, nullptr_t) noexcept;
-template <class T, class D>
-    bool operator!=(nullptr_t, const unique_ptr<T, D>& y) noexcept;
-
-template <class T, class D>
-    bool operator<(const unique_ptr<T, D>& x, nullptr_t);
-template <class T, class D>
-    bool operator<(nullptr_t, const unique_ptr<T, D>& y);
-template <class T, class D>
-    bool operator<=(const unique_ptr<T, D>& x, nullptr_t);
-template <class T, class D>
-    bool operator<=(nullptr_t, const unique_ptr<T, D>& y);
-template <class T, class D>
-    bool operator>(const unique_ptr<T, D>& x, nullptr_t);
-template <class T, class D>
-    bool operator>(nullptr_t, const unique_ptr<T, D>& y);
-template <class T, class D>
-    bool operator>=(const unique_ptr<T, D>& x, nullptr_t);
-template <class T, class D>
-    bool operator>=(nullptr_t, const unique_ptr<T, D>& y);
-
-class bad_weak_ptr
-    : public std::exception
-{
-    bad_weak_ptr() noexcept;
-};
-
-template<class T, class... Args> unique_ptr<T> make_unique(Args&&... args);     // C++14
-template<class T>                unique_ptr<T> make_unique(size_t n);           // C++14
-template<class T, class... Args> unspecified   make_unique(Args&&...) = delete; // C++14, T == U[N]
-
-template<class E, class T, class Y, class D>
-    basic_ostream<E, T>& operator<< (basic_ostream<E, T>& os, unique_ptr<Y, D> const& p);
-
-template<class T>
-class shared_ptr
-{
-public:
-    typedef T element_type;
-    typedef weak_ptr<T> weak_type; // C++17
-
-    // constructors:
-    constexpr shared_ptr() noexcept;
-    template<class Y> explicit shared_ptr(Y* p);
-    template<class Y, class D> shared_ptr(Y* p, D d);
-    template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
-    template <class D> shared_ptr(nullptr_t p, D d);
-    template <class D, class A> shared_ptr(nullptr_t p, D d, A a);
-    template<class Y> shared_ptr(const shared_ptr<Y>& r, T *p) noexcept;
-    shared_ptr(const shared_ptr& r) noexcept;
-    template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
-    shared_ptr(shared_ptr&& r) noexcept;
-    template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
-    template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
-    template<class Y> shared_ptr(auto_ptr<Y>&& r);          // removed in C++17
-    template <class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
-    shared_ptr(nullptr_t) : shared_ptr() { }
-
-    // destructor:
-    ~shared_ptr();
-
-    // assignment:
-    shared_ptr& operator=(const shared_ptr& r) noexcept;
-    template<class Y> shared_ptr& operator=(const shared_ptr<Y>& r) noexcept;
-    shared_ptr& operator=(shared_ptr&& r) noexcept;
-    template<class Y> shared_ptr& operator=(shared_ptr<Y>&& r);
-    template<class Y> shared_ptr& operator=(auto_ptr<Y>&& r); // removed in C++17
-    template <class Y, class D> shared_ptr& operator=(unique_ptr<Y, D>&& r);
-
-    // modifiers:
-    void swap(shared_ptr& r) noexcept;
-    void reset() noexcept;
-    template<class Y> void reset(Y* p);
-    template<class Y, class D> void reset(Y* p, D d);
-    template<class Y, class D, class A> void reset(Y* p, D d, A a);
-
-    // observers:
-    T* get() const noexcept;
-    T& operator*() const noexcept;
-    T* operator->() const noexcept;
-    long use_count() const noexcept;
-    bool unique() const noexcept;
-    explicit operator bool() const noexcept;
-    template<class U> bool owner_before(shared_ptr<U> const& b) const noexcept;
-    template<class U> bool owner_before(weak_ptr<U> const& b) const noexcept;
-};
-
-template<class T>
-shared_ptr(weak_ptr<T>) -> shared_ptr<T>;
-template<class T, class D>
-shared_ptr(unique_ptr<T, D>) -> shared_ptr<T>;
-
-// shared_ptr comparisons:
-template<class T, class U>
-    bool operator==(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
-template<class T, class U>
-    bool operator!=(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
-template<class T, class U>
-    bool operator<(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
-template<class T, class U>
-    bool operator>(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
-template<class T, class U>
-    bool operator<=(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
-template<class T, class U>
-    bool operator>=(shared_ptr<T> const& a, shared_ptr<U> const& b) noexcept;
-
-template <class T>
-    bool operator==(const shared_ptr<T>& x, nullptr_t) noexcept;
-template <class T>
-    bool operator==(nullptr_t, const shared_ptr<T>& y) noexcept;
-template <class T>
-    bool operator!=(const shared_ptr<T>& x, nullptr_t) noexcept;
-template <class T>
-    bool operator!=(nullptr_t, const shared_ptr<T>& y) noexcept;
-template <class T>
-    bool operator<(const shared_ptr<T>& x, nullptr_t) noexcept;
-template <class T>
-bool operator<(nullptr_t, const shared_ptr<T>& y) noexcept;
-template <class T>
-    bool operator<=(const shared_ptr<T>& x, nullptr_t) noexcept;
-template <class T>
-    bool operator<=(nullptr_t, const shared_ptr<T>& y) noexcept;
-template <class T>
-    bool operator>(const shared_ptr<T>& x, nullptr_t) noexcept;
-template <class T>
-    bool operator>(nullptr_t, const shared_ptr<T>& y) noexcept;
-template <class T>
-    bool operator>=(const shared_ptr<T>& x, nullptr_t) noexcept;
-template <class T>
-    bool operator>=(nullptr_t, const shared_ptr<T>& y) noexcept;
-
-// shared_ptr specialized algorithms:
-template<class T> void swap(shared_ptr<T>& a, shared_ptr<T>& b) noexcept;
-
-// shared_ptr casts:
-template<class T, class U>
-    shared_ptr<T> static_pointer_cast(shared_ptr<U> const& r) noexcept;
-template<class T, class U>
-    shared_ptr<T> dynamic_pointer_cast(shared_ptr<U> const& r) noexcept;
-template<class T, class U>
-    shared_ptr<T> const_pointer_cast(shared_ptr<U> const& r) noexcept;
-
-// shared_ptr I/O:
-template<class E, class T, class Y>
-    basic_ostream<E, T>& operator<< (basic_ostream<E, T>& os, shared_ptr<Y> const& p);
-
-// shared_ptr get_deleter:
-template<class D, class T> D* get_deleter(shared_ptr<T> const& p) noexcept;
-
-template<class T, class... Args>
-    shared_ptr<T> make_shared(Args&&... args);
-template<class T, class A, class... Args>
-    shared_ptr<T> allocate_shared(const A& a, Args&&... args);
-
-template<class T>
-class weak_ptr
-{
-public:
-    typedef T element_type;
-
-    // constructors
-    constexpr weak_ptr() noexcept;
-    template<class Y> weak_ptr(shared_ptr<Y> const& r) noexcept;
-    weak_ptr(weak_ptr const& r) noexcept;
-    template<class Y> weak_ptr(weak_ptr<Y> const& r) noexcept;
-    weak_ptr(weak_ptr&& r) noexcept;                      // C++14
-    template<class Y> weak_ptr(weak_ptr<Y>&& r) noexcept; // C++14
-
-    // destructor
-    ~weak_ptr();
-
-    // assignment
-    weak_ptr& operator=(weak_ptr const& r) noexcept;
-    template<class Y> weak_ptr& operator=(weak_ptr<Y> const& r) noexcept;
-    template<class Y> weak_ptr& operator=(shared_ptr<Y> const& r) noexcept;
-    weak_ptr& operator=(weak_ptr&& r) noexcept;                      // C++14
-    template<class Y> weak_ptr& operator=(weak_ptr<Y>&& r) noexcept; // C++14
-
-    // modifiers
-    void swap(weak_ptr& r) noexcept;
-    void reset() noexcept;
-
-    // observers
-    long use_count() const noexcept;
-    bool expired() const noexcept;
-    shared_ptr<T> lock() const noexcept;
-    template<class U> bool owner_before(shared_ptr<U> const& b) const noexcept;
-    template<class U> bool owner_before(weak_ptr<U> const& b) const noexcept;
-};
-
-template<class T>
-weak_ptr(shared_ptr<T>) -> weak_ptr<T>;
-
-// weak_ptr specialized algorithms:
-template<class T> void swap(weak_ptr<T>& a, weak_ptr<T>& b) noexcept;
-
-// class owner_less:
-template<class T> struct owner_less;
-
-template<class T>
-struct owner_less<shared_ptr<T> >
-    : binary_function<shared_ptr<T>, shared_ptr<T>, bool>
-{
-    typedef bool result_type;
-    bool operator()(shared_ptr<T> const&, shared_ptr<T> const&) const noexcept;
-    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const noexcept;
-    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const noexcept;
-};
-
-template<class T>
-struct owner_less<weak_ptr<T> >
-    : binary_function<weak_ptr<T>, weak_ptr<T>, bool>
-{
-    typedef bool result_type;
-    bool operator()(weak_ptr<T> const&, weak_ptr<T> const&) const noexcept;
-    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const noexcept;
-    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const noexcept;
-};
-
-template <>  // Added in C++14
-struct owner_less<void>
-{
-    template <class _Tp, class _Up>
-    bool operator()( shared_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const noexcept;
-    template <class _Tp, class _Up>
-    bool operator()( shared_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const noexcept;
-    template <class _Tp, class _Up>
-    bool operator()(   weak_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const noexcept;
-    template <class _Tp, class _Up>
-    bool operator()(   weak_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const noexcept;
-
-    typedef void is_transparent;
-};
-
-template<class T>
-class enable_shared_from_this
-{
-protected:
-    constexpr enable_shared_from_this() noexcept;
-    enable_shared_from_this(enable_shared_from_this const&) noexcept;
-    enable_shared_from_this& operator=(enable_shared_from_this const&) noexcept;
-    ~enable_shared_from_this();
-public:
-    shared_ptr<T> shared_from_this();
-    shared_ptr<T const> shared_from_this() const;
-};
-
-template<class T>
-    bool atomic_is_lock_free(const shared_ptr<T>* p);
-template<class T>
-    shared_ptr<T> atomic_load(const shared_ptr<T>* p);
-template<class T>
-    shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);
-template<class T>
-    void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);
-template<class T>
-    void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
-template<class T>
-    shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);
-template<class T>
-    shared_ptr<T>
-    atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
-template<class T>
-    bool
-    atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
-template<class T>
-    bool
-    atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
-template<class T>
-    bool
-    atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
-                                          shared_ptr<T> w, memory_order success,
-                                          memory_order failure);
-template<class T>
-    bool
-    atomic_compare_exchange_strong_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
-                                            shared_ptr<T> w, memory_order success,
-                                            memory_order failure);
-// Hash support
-template <class T> struct hash;
-template <class T, class D> struct hash<unique_ptr<T, D> >;
-template <class T> struct hash<shared_ptr<T> >;
-
-template <class T, class Alloc>
-  inline constexpr bool uses_allocator_v = uses_allocator<T, Alloc>::value;
-
-// Pointer safety
-enum class pointer_safety { relaxed, preferred, strict }; // since C++11
-void declare_reachable(void *p);                          // since C++11
-template <class T> T *undeclare_reachable(T *p);          // since C++11
-void declare_no_pointers(char *p, size_t n);              // since C++11
-void undeclare_no_pointers(char *p, size_t n);            // since C++11
-pointer_safety get_pointer_safety() noexcept;             // since C++11
-
-void* align(size_t alignment, size_t size, void*& ptr, size_t& space);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/memory.syn.
 
 #include <__config>
 #include <__functional_base>
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -10,181 +10,7 @@
 #ifndef _LIBCPP_MUTEX
 #define _LIBCPP_MUTEX
 
-/*
-    mutex synopsis
-
-namespace std
-{
-
-class mutex
-{
-public:
-     constexpr mutex() noexcept;
-     ~mutex();
-
-    mutex(const mutex&) = delete;
-    mutex& operator=(const mutex&) = delete;
-
-    void lock();
-    bool try_lock();
-    void unlock();
-
-    typedef pthread_mutex_t* native_handle_type;
-    native_handle_type native_handle();
-};
-
-class recursive_mutex
-{
-public:
-     recursive_mutex();
-     ~recursive_mutex();
-
-    recursive_mutex(const recursive_mutex&) = delete;
-    recursive_mutex& operator=(const recursive_mutex&) = delete;
-
-    void lock();
-    bool try_lock() noexcept;
-    void unlock();
-
-    typedef pthread_mutex_t* native_handle_type;
-    native_handle_type native_handle();
-};
-
-class timed_mutex
-{
-public:
-     timed_mutex();
-     ~timed_mutex();
-
-    timed_mutex(const timed_mutex&) = delete;
-    timed_mutex& operator=(const timed_mutex&) = delete;
-
-    void lock();
-    bool try_lock();
-    template <class Rep, class Period>
-        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
-    template <class Clock, class Duration>
-        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
-    void unlock();
-};
-
-class recursive_timed_mutex
-{
-public:
-     recursive_timed_mutex();
-     ~recursive_timed_mutex();
-
-    recursive_timed_mutex(const recursive_timed_mutex&) = delete;
-    recursive_timed_mutex& operator=(const recursive_timed_mutex&) = delete;
-
-    void lock();
-    bool try_lock() noexcept;
-    template <class Rep, class Period>
-        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
-    template <class Clock, class Duration>
-        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
-    void unlock();
-};
-
-struct defer_lock_t { explicit defer_lock_t() = default; };
-struct try_to_lock_t { explicit try_to_lock_t() = default; };
-struct adopt_lock_t { explicit adopt_lock_t() = default; };
-
-inline constexpr defer_lock_t  defer_lock{};
-inline constexpr try_to_lock_t try_to_lock{};
-inline constexpr adopt_lock_t  adopt_lock{};
-
-template <class Mutex>
-class lock_guard
-{
-public:
-    typedef Mutex mutex_type;
-
-    explicit lock_guard(mutex_type& m);
-    lock_guard(mutex_type& m, adopt_lock_t);
-    ~lock_guard();
-
-    lock_guard(lock_guard const&) = delete;
-    lock_guard& operator=(lock_guard const&) = delete;
-};
-
-template <class... MutexTypes>
-class scoped_lock // C++17
-{
-public:
-    using mutex_type = Mutex;  // If MutexTypes... consists of the single type Mutex
-
-    explicit scoped_lock(MutexTypes&... m);
-    scoped_lock(adopt_lock_t, MutexTypes&... m);
-    ~scoped_lock();
-    scoped_lock(scoped_lock const&) = delete;
-    scoped_lock& operator=(scoped_lock const&) = delete;
-private:
-    tuple<MutexTypes&...> pm; // exposition only
-};
-
-template <class Mutex>
-class unique_lock
-{
-public:
-    typedef Mutex mutex_type;
-    unique_lock() noexcept;
-    explicit unique_lock(mutex_type& m);
-    unique_lock(mutex_type& m, defer_lock_t) noexcept;
-    unique_lock(mutex_type& m, try_to_lock_t);
-    unique_lock(mutex_type& m, adopt_lock_t);
-    template <class Clock, class Duration>
-        unique_lock(mutex_type& m, const chrono::time_point<Clock, Duration>& abs_time);
-    template <class Rep, class Period>
-        unique_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
-    ~unique_lock();
-
-    unique_lock(unique_lock const&) = delete;
-    unique_lock& operator=(unique_lock const&) = delete;
-
-    unique_lock(unique_lock&& u) noexcept;
-    unique_lock& operator=(unique_lock&& u) noexcept;
-
-    void lock();
-    bool try_lock();
-
-    template <class Rep, class Period>
-        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
-    template <class Clock, class Duration>
-        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
-
-    void unlock();
-
-    void swap(unique_lock& u) noexcept;
-    mutex_type* release() noexcept;
-
-    bool owns_lock() const noexcept;
-    explicit operator bool () const noexcept;
-    mutex_type* mutex() const noexcept;
-};
-
-template <class Mutex>
-  void swap(unique_lock<Mutex>& x, unique_lock<Mutex>& y) noexcept;
-
-template <class L1, class L2, class... L3>
-  int try_lock(L1&, L2&, L3&...);
-template <class L1, class L2, class... L3>
-  void lock(L1&, L2&, L3&...);
-
-struct once_flag
-{
-    constexpr once_flag() noexcept;
-
-    once_flag(const once_flag&) = delete;
-    once_flag& operator=(const once_flag&) = delete;
-};
-
-template<class Callable, class ...Args>
-  void call_once(once_flag& flag, Callable&& func, Args&&... args);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/mutex.syn.
 
 #include <__config>
 #include <__mutex_base>
diff --git a/libcxx/include/new b/libcxx/include/new
--- a/libcxx/include/new
+++ b/libcxx/include/new
@@ -10,81 +10,7 @@
 #ifndef _LIBCPP_NEW
 #define _LIBCPP_NEW
 
-/*
-    new synopsis
-
-namespace std
-{
-
-class bad_alloc
-    : public exception
-{
-public:
-    bad_alloc() noexcept;
-    bad_alloc(const bad_alloc&) noexcept;
-    bad_alloc& operator=(const bad_alloc&) noexcept;
-    virtual const char* what() const noexcept;
-};
-
-class bad_array_new_length : public bad_alloc // C++14
-{
-public:
-    bad_array_new_length() noexcept;
-};
-
-enum class align_val_t : size_t {}; // C++17
-
-struct destroying_delete_t { // C++20
-  explicit destroying_delete_t() = default;
-};
-inline constexpr destroying_delete_t destroying_delete{}; // C++20
-
-struct nothrow_t { explicit nothrow_t() = default; };
-extern const nothrow_t nothrow;
-typedef void (*new_handler)();
-new_handler set_new_handler(new_handler new_p) noexcept;
-new_handler get_new_handler() noexcept;
-
-// 21.6.4, pointer optimization barrier
-template <class T> constexpr T* launder(T* p) noexcept; // C++17
-}  // std
-
-void* operator new(std::size_t size);                                   // replaceable, nodiscard in C++20
-void* operator new(std::size_t size, std::align_val_t alignment);       // replaceable, C++17, nodiscard in C++20
-void* operator new(std::size_t size, const std::nothrow_t&) noexcept;   // replaceable, nodiscard in C++20
-void* operator new(std::size_t size, std::align_val_t alignment,
-                   const std::nothrow_t&) noexcept;                     // replaceable, C++17, nodiscard in C++20
-void  operator delete(void* ptr) noexcept;                              // replaceable
-void  operator delete(void* ptr, std::size_t size) noexcept;            // replaceable, C++14
-void  operator delete(void* ptr, std::align_val_t alignment) noexcept;  // replaceable, C++17
-void  operator delete(void* ptr, std::size_t size,
-                      std::align_val_t alignment) noexcept;             // replaceable, C++17
-void  operator delete(void* ptr, const std::nothrow_t&) noexcept;       // replaceable
-void  operator delete(void* ptr, std:align_val_t alignment,
-                      const std::nothrow_t&) noexcept;                  // replaceable, C++17
-
-void* operator new[](std::size_t size);                                 // replaceable, nodiscard in C++20
-void* operator new[](std::size_t size,
-                     std::align_val_t alignment) noexcept;              // replaceable, C++17, nodiscard in C++20
-void* operator new[](std::size_t size, const std::nothrow_t&) noexcept; // replaceable, nodiscard in C++20
-void* operator new[](std::size_t size, std::align_val_t alignment,
-                     const std::nothrow_t&) noexcept;                   // replaceable, C++17, nodiscard in C++20
-void  operator delete[](void* ptr) noexcept;                            // replaceable
-void  operator delete[](void* ptr, std::size_t size) noexcept;          // replaceable, C++14
-void  operator delete[](void* ptr,
-                        std::align_val_t alignment) noexcept;           // replaceable, C++17
-void  operator delete[](void* ptr, std::size_t size,
-                        std::align_val_t alignment) noexcept;           // replaceable, C++17
-void  operator delete[](void* ptr, const std::nothrow_t&) noexcept;     // replaceable
-void  operator delete[](void* ptr, std::align_val_t alignment,
-                        const std::nothrow_t&) noexcept;                // replaceable, C++17
-
-void* operator new  (std::size_t size, void* ptr) noexcept;             // nodiscard in C++20
-void* operator new[](std::size_t size, void* ptr) noexcept;             // nodiscard in C++20
-void  operator delete  (void* ptr, void*) noexcept;
-void  operator delete[](void* ptr, void*) noexcept;
-
-*/
+// Synopsis avaiable at http://wg21.link/new.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/numbers b/libcxx/include/numbers
--- a/libcxx/include/numbers
+++ b/libcxx/include/numbers
@@ -10,53 +10,7 @@
 #ifndef _LIBCPP_NUMBERS
 #define _LIBCPP_NUMBERS
 
-/*
-    numbers synopsis
-
-namespace std::numbers {
-  template<class T> inline constexpr T e_v          = unspecified;
-  template<class T> inline constexpr T log2e_v      = unspecified;
-  template<class T> inline constexpr T log10e_v     = unspecified;
-  template<class T> inline constexpr T pi_v         = unspecified;
-  template<class T> inline constexpr T inv_pi_v     = unspecified;
-  template<class T> inline constexpr T inv_sqrtpi_v = unspecified;
-  template<class T> inline constexpr T ln2_v        = unspecified;
-  template<class T> inline constexpr T ln10_v       = unspecified;
-  template<class T> inline constexpr T sqrt2_v      = unspecified;
-  template<class T> inline constexpr T sqrt3_v      = unspecified;
-  template<class T> inline constexpr T inv_sqrt3_v  = unspecified;
-  template<class T> inline constexpr T egamma_v     = unspecified;
-  template<class T> inline constexpr T phi_v        = unspecified;
-
-  template<floating_point T> inline constexpr T e_v<T>          = see below;
-  template<floating_point T> inline constexpr T log2e_v<T>      = see below;
-  template<floating_point T> inline constexpr T log10e_v<T>     = see below;
-  template<floating_point T> inline constexpr T pi_v<T>         = see below;
-  template<floating_point T> inline constexpr T inv_pi_v<T>     = see below;
-  template<floating_point T> inline constexpr T inv_sqrtpi_v<T> = see below;
-  template<floating_point T> inline constexpr T ln2_v<T>        = see below;
-  template<floating_point T> inline constexpr T ln10_v<T>       = see below;
-  template<floating_point T> inline constexpr T sqrt2_v<T>      = see below;
-  template<floating_point T> inline constexpr T sqrt3_v<T>      = see below;
-  template<floating_point T> inline constexpr T inv_sqrt3_v<T>  = see below;
-  template<floating_point T> inline constexpr T egamma_v<T>     = see below;
-  template<floating_point T> inline constexpr T phi_v<T>        = see below;
-
-  inline constexpr double e          = e_v<double>;
-  inline constexpr double log2e      = log2e_v<double>;
-  inline constexpr double log10e     = log10e_v<double>;
-  inline constexpr double pi         = pi_v<double>;
-  inline constexpr double inv_pi     = inv_pi_v<double>;
-  inline constexpr double inv_sqrtpi = inv_sqrtpi_v<double>;
-  inline constexpr double ln2        = ln2_v<double>;
-  inline constexpr double ln10       = ln10_v<double>;
-  inline constexpr double sqrt2      = sqrt2_v<double>;
-  inline constexpr double sqrt3      = sqrt3_v<double>;
-  inline constexpr double inv_sqrt3  = inv_sqrt3_v<double>;
-  inline constexpr double egamma     = egamma_v<double>;
-  inline constexpr double phi        = phi_v<double>;
-}
-*/
+// Synopsis avaiable at http://wg21.link/numbers.syn.
 
 #include <__config>
 #include <concepts>
diff --git a/libcxx/include/numeric b/libcxx/include/numeric
--- a/libcxx/include/numeric
+++ b/libcxx/include/numeric
@@ -10,139 +10,7 @@
 #ifndef _LIBCPP_NUMERIC
 #define _LIBCPP_NUMERIC
 
-/*
-    numeric synopsis
-
-namespace std
-{
-
-template <class InputIterator, class T>
-    constexpr T  // constexpr since C++20
-    accumulate(InputIterator first, InputIterator last, T init);
-
-template <class InputIterator, class T, class BinaryOperation>
-    constexpr T  // constexpr since C++20
-    accumulate(InputIterator first, InputIterator last, T init, BinaryOperation binary_op);
-
-template<class InputIterator>
-    constexpr typename iterator_traits<InputIterator>::value_type  // constexpr since C++20
-    reduce(InputIterator first, InputIterator last);  // C++17
-
-template<class InputIterator, class T>
-    constexpr T  // constexpr since C++20
-    reduce(InputIterator first, InputIterator last, T init);  // C++17
-
-template<class InputIterator, class T, class BinaryOperation>
-    constexpr T  // constexpr since C++20
-    reduce(InputIterator first, InputIterator last, T init, BinaryOperation binary_op);  // C++17
-
-template <class InputIterator1, class InputIterator2, class T>
-    constexpr T  // constexpr since C++20
-    inner_product(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, T init);
-
-template <class InputIterator1, class InputIterator2, class T, class BinaryOperation1, class BinaryOperation2>
-    constexpr T  // constexpr since C++20
-    inner_product(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2,
-                  T init, BinaryOperation1 binary_op1, BinaryOperation2 binary_op2);
-
-
-template<class InputIterator1, class InputIterator2, class T>
-    constexpr T  // constexpr since C++20
-    transform_reduce(InputIterator1 first1, InputIterator1 last1,
-                     InputIterator2 first2, T init);  // C++17
-
-template<class InputIterator1, class InputIterator2, class T, class BinaryOperation1, class BinaryOperation2>
-    constexpr T  // constexpr since C++20
-    transform_reduce(InputIterator1 first1, InputIterator1 last1,
-                     InputIterator2 first2, T init,
-                     BinaryOperation1 binary_op1, BinaryOperation2 binary_op2);  // C++17
-
-template<class InputIterator, class T, class BinaryOperation, class UnaryOperation>
-    constexpr T  // constexpr since C++20
-    transform_reduce(InputIterator first, InputIterator last, T init,
-                     BinaryOperation binary_op, UnaryOperation unary_op);  // C++17
-
-template <class InputIterator, class OutputIterator>
-    constexpr OutputIterator  // constexpr since C++20
-    partial_sum(InputIterator first, InputIterator last, OutputIterator result);
-
-template <class InputIterator, class OutputIterator, class BinaryOperation>
-    constexpr OutputIterator  // constexpr since C++20
-    partial_sum(InputIterator first, InputIterator last, OutputIterator result, BinaryOperation binary_op);
-
-template<class InputIterator, class OutputIterator, class T>
-    constexpr OutputIterator  // constexpr since C++20
-    exclusive_scan(InputIterator first, InputIterator last,
-                   OutputIterator result, T init); // C++17
-
-template<class InputIterator, class OutputIterator, class T, class BinaryOperation>
-    constexpr OutputIterator  // constexpr since C++20
-    exclusive_scan(InputIterator first, InputIterator last,
-                   OutputIterator result, T init, BinaryOperation binary_op); // C++17
-
-template<class InputIterator, class OutputIterator>
-    constexpr OutputIterator  // constexpr since C++20
-    inclusive_scan(InputIterator first, InputIterator last, OutputIterator result);  // C++17
-
-template<class InputIterator, class OutputIterator, class BinaryOperation>
-    constexpr OutputIterator  // constexpr since C++20
-    inclusive_scan(InputIterator first, InputIterator last,
-                   OutputIterator result, BinaryOperation binary_op);  // C++17
-
-template<class InputIterator, class OutputIterator, class BinaryOperation, class T>
-    constexpr OutputIterator  // constexpr since C++20
-    inclusive_scan(InputIterator first, InputIterator last,
-                   OutputIterator result, BinaryOperation binary_op, T init);  // C++17
-
-template<class InputIterator, class OutputIterator, class T,
-         class BinaryOperation, class UnaryOperation>
-    constexpr OutputIterator  // constexpr since C++20
-    transform_exclusive_scan(InputIterator first, InputIterator last,
-                             OutputIterator result, T init,
-                             BinaryOperation binary_op, UnaryOperation unary_op);  // C++17
-
-template<class InputIterator, class OutputIterator,
-         class BinaryOperation, class UnaryOperation>
-    constexpr OutputIterator  // constexpr since C++20
-    transform_inclusive_scan(InputIterator first, InputIterator last,
-                             OutputIterator result,
-                             BinaryOperation binary_op, UnaryOperation unary_op);  // C++17
-
-template<class InputIterator, class OutputIterator,
-         class BinaryOperation, class UnaryOperation, class T>
-    constexpr OutputIterator  // constexpr since C++20
-    transform_inclusive_scan(InputIterator first, InputIterator last,
-                             OutputIterator result,
-                             BinaryOperation binary_op, UnaryOperation unary_op,
-                             T init);  // C++17
-
-template <class InputIterator, class OutputIterator>
-    constexpr OutputIterator  // constexpr since C++20
-    adjacent_difference(InputIterator first, InputIterator last, OutputIterator result);
-
-template <class InputIterator, class OutputIterator, class BinaryOperation>
-    constexpr OutputIterator  // constexpr since C++20
-    adjacent_difference(InputIterator first, InputIterator last, OutputIterator result, BinaryOperation binary_op);
-
-template <class ForwardIterator, class T>
-    constexpr void  // constexpr since C++20
-    iota(ForwardIterator first, ForwardIterator last, T value);
-
-template <class M, class N>
-    constexpr common_type_t<M,N> gcd(M m, N n);    // C++17
-
-template <class M, class N>
-    constexpr common_type_t<M,N> lcm(M m, N n);    // C++17
-
-template<class T>
-    constexpr T midpoint(T a, T b) noexcept;  // C++20
-
-template<class T>
-    constexpr T* midpoint(T* a, T* b);        // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/numeric.ops.overview.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/optional b/libcxx/include/optional
--- a/libcxx/include/optional
+++ b/libcxx/include/optional
@@ -10,141 +10,7 @@
 #ifndef _LIBCPP_OPTIONAL
 #define _LIBCPP_OPTIONAL
 
-/*
-    optional synopsis
-
-// C++1z
-
-namespace std {
-  // 23.6.3, optional for object types
-  template <class T> class optional;
-
-  // 23.6.4, no-value state indicator
-  struct nullopt_t{see below };
-  inline constexpr nullopt_t nullopt(unspecified );
-
-  // 23.6.5, class bad_optional_access
-  class bad_optional_access;
-
-  // 23.6.6, relational operators
-  template <class T, class U>
-  constexpr bool operator==(const optional<T>&, const optional<U>&);
-  template <class T, class U>
-  constexpr bool operator!=(const optional<T>&, const optional<U>&);
-  template <class T, class U>
-  constexpr bool operator<(const optional<T>&, const optional<U>&);
-  template <class T, class U>
-  constexpr bool operator>(const optional<T>&, const optional<U>&);
-  template <class T, class U>
-  constexpr bool operator<=(const optional<T>&, const optional<U>&);
-  template <class T, class U>
-  constexpr bool operator>=(const optional<T>&, const optional<U>&);
-
-  // 23.6.7 comparison with nullopt
-  template <class T> constexpr bool operator==(const optional<T>&, nullopt_t) noexcept;
-  template <class T> constexpr bool operator==(nullopt_t, const optional<T>&) noexcept;
-  template <class T> constexpr bool operator!=(const optional<T>&, nullopt_t) noexcept;
-  template <class T> constexpr bool operator!=(nullopt_t, const optional<T>&) noexcept;
-  template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept;
-  template <class T> constexpr bool operator<(nullopt_t, const optional<T>&) noexcept;
-  template <class T> constexpr bool operator<=(const optional<T>&, nullopt_t) noexcept;
-  template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept;
-  template <class T> constexpr bool operator>(const optional<T>&, nullopt_t) noexcept;
-  template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept;
-  template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept;
-  template <class T> constexpr bool operator>=(nullopt_t, const optional<T>&) noexcept;
-
-  // 23.6.8, comparison with T
-  template <class T, class U> constexpr bool operator==(const optional<T>&, const U&);
-  template <class T, class U> constexpr bool operator==(const T&, const optional<U>&);
-  template <class T, class U> constexpr bool operator!=(const optional<T>&, const U&);
-  template <class T, class U> constexpr bool operator!=(const T&, const optional<U>&);
-  template <class T, class U> constexpr bool operator<(const optional<T>&, const U&);
-  template <class T, class U> constexpr bool operator<(const T&, const optional<U>&);
-  template <class T, class U> constexpr bool operator<=(const optional<T>&, const U&);
-  template <class T, class U> constexpr bool operator<=(const T&, const optional<U>&);
-  template <class T, class U> constexpr bool operator>(const optional<T>&, const U&);
-  template <class T, class U> constexpr bool operator>(const T&, const optional<U>&);
-  template <class T, class U> constexpr bool operator>=(const optional<T>&, const U&);
-  template <class T, class U> constexpr bool operator>=(const T&, const optional<U>&);
-
-  // 23.6.9, specialized algorithms
-  template <class T> void swap(optional<T>&, optional<T>&) noexcept(see below ); // constexpr in C++20
-  template <class T> constexpr optional<see below > make_optional(T&&);
-  template <class T, class... Args>
-    constexpr optional<T> make_optional(Args&&... args);
-  template <class T, class U, class... Args>
-    constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args);
-
-  // 23.6.10, hash support
-  template <class T> struct hash;
-  template <class T> struct hash<optional<T>>;
-
-  template <class T> class optional {
-  public:
-    using value_type = T;
-
-    // 23.6.3.1, constructors
-    constexpr optional() noexcept;
-    constexpr optional(nullopt_t) noexcept;
-    optional(const optional &);
-    optional(optional &&) noexcept(see below);
-    template <class... Args> constexpr explicit optional(in_place_t, Args &&...);
-    template <class U, class... Args>
-      constexpr explicit optional(in_place_t, initializer_list<U>, Args &&...);
-    template <class U = T>
-      constexpr EXPLICIT optional(U &&);
-    template <class U>
-      EXPLICIT optional(const optional<U> &);   // constexpr in C++20
-    template <class U>
-      EXPLICIT optional(optional<U> &&);        // constexpr in C++20
-
-    // 23.6.3.2, destructor
-    ~optional(); // constexpr in C++20
-
-    // 23.6.3.3, assignment
-    optional &operator=(nullopt_t) noexcept;                     // constexpr in C++20
-    optional &operator=(const optional &);                       // constexpr in C++20
-    optional &operator=(optional &&) noexcept(see below);        // constexpr in C++20
-    template <class U = T> optional &operator=(U &&);            // constexpr in C++20
-    template <class U> optional &operator=(const optional<U> &); // constexpr in C++20
-    template <class U> optional &operator=(optional<U> &&);      // constexpr in C++20
-    template <class... Args> T& emplace(Args &&...);             // constexpr in C++20
-    template <class U, class... Args>
-      T& emplace(initializer_list<U>, Args &&...);               // constexpr in C++20
-
-    // 23.6.3.4, swap
-    void swap(optional &) noexcept(see below ); // constexpr in C++20
-
-    // 23.6.3.5, observers
-    constexpr T const *operator->() const;
-    constexpr T *operator->();
-    constexpr T const &operator*() const &;
-    constexpr T &operator*() &;
-    constexpr T &&operator*() &&;
-    constexpr const T &&operator*() const &&;
-    constexpr explicit operator bool() const noexcept;
-    constexpr bool has_value() const noexcept;
-    constexpr T const &value() const &;
-    constexpr T &value() &;
-    constexpr T &&value() &&;
-    constexpr const T &&value() const &&;
-    template <class U> constexpr T value_or(U &&) const &;
-    template <class U> constexpr T value_or(U &&) &&;
-
-    // 23.6.3.6, modifiers
-    void reset() noexcept; // constexpr in C++20
-
-  private:
-    T *val; // exposition only
-  };
-
-template<class T>
-  optional(T) -> optional<T>;
-
-} // namespace std
-
-*/
+// Synopsis avaiable at http://wg21.link/optional.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/ostream b/libcxx/include/ostream
--- a/libcxx/include/ostream
+++ b/libcxx/include/ostream
@@ -10,128 +10,7 @@
 #ifndef _LIBCPP_OSTREAM
 #define _LIBCPP_OSTREAM
 
-/*
-    ostream synopsis
-
-template <class charT, class traits = char_traits<charT> >
-class basic_ostream
-    : virtual public basic_ios<charT,traits>
-{
-public:
-    // types (inherited from basic_ios (27.5.4)):
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    // 27.7.2.2 Constructor/destructor:
-    explicit basic_ostream(basic_streambuf<char_type,traits>* sb);
-    basic_ostream(basic_ostream&& rhs);
-    virtual ~basic_ostream();
-
-    // 27.7.2.3 Assign/swap
-    basic_ostream& operator=(const basic_ostream& rhs) = delete; // C++14
-    basic_ostream& operator=(basic_ostream&& rhs);
-    void swap(basic_ostream& rhs);
-
-    // 27.7.2.4 Prefix/suffix:
-    class sentry;
-
-    // 27.7.2.6 Formatted output:
-    basic_ostream& operator<<(basic_ostream& (*pf)(basic_ostream&));
-    basic_ostream& operator<<(basic_ios<charT, traits>& (*pf)(basic_ios<charT,traits>&));
-    basic_ostream& operator<<(ios_base& (*pf)(ios_base&));
-    basic_ostream& operator<<(bool n);
-    basic_ostream& operator<<(short n);
-    basic_ostream& operator<<(unsigned short n);
-    basic_ostream& operator<<(int n);
-    basic_ostream& operator<<(unsigned int n);
-    basic_ostream& operator<<(long n);
-    basic_ostream& operator<<(unsigned long n);
-    basic_ostream& operator<<(long long n);
-    basic_ostream& operator<<(unsigned long long n);
-    basic_ostream& operator<<(float f);
-    basic_ostream& operator<<(double f);
-    basic_ostream& operator<<(long double f);
-    basic_ostream& operator<<(const void* p);
-    basic_ostream& operator<<(basic_streambuf<char_type,traits>* sb);
-    basic_ostream& operator<<(nullptr_t);
-
-    // 27.7.2.7 Unformatted output:
-    basic_ostream& put(char_type c);
-    basic_ostream& write(const char_type* s, streamsize n);
-    basic_ostream& flush();
-
-    // 27.7.2.5 seeks:
-    pos_type tellp();
-    basic_ostream& seekp(pos_type);
-    basic_ostream& seekp(off_type, ios_base::seekdir);
-protected:
-    basic_ostream(const basic_ostream& rhs) = delete;
-    basic_ostream(basic_ostream&& rhs);
-    // 27.7.3.3 Assign/swap
-    basic_ostream& operator=(basic_ostream& rhs) = delete;
-    basic_ostream& operator=(const basic_ostream&& rhs);
-    void swap(basic_ostream& rhs);
-};
-
-// 27.7.2.6.4 character inserters
-
-template<class charT, class traits>
-  basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, charT);
-
-template<class charT, class traits>
-  basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, char);
-
-template<class traits>
-  basic_ostream<char,traits>& operator<<(basic_ostream<char,traits>&, char);
-
-// signed and unsigned
-
-template<class traits>
-  basic_ostream<char,traits>& operator<<(basic_ostream<char,traits>&, signed char);
-
-template<class traits>
-  basic_ostream<char,traits>& operator<<(basic_ostream<char,traits>&, unsigned char);
-
-// NTBS
-template<class charT, class traits>
-  basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, const charT*);
-
-template<class charT, class traits>
-  basic_ostream<charT,traits>& operator<<(basic_ostream<charT,traits>&, const char*);
-
-template<class traits>
-  basic_ostream<char,traits>& operator<<(basic_ostream<char,traits>&, const char*);
-
-// signed and unsigned
-template<class traits>
-basic_ostream<char,traits>& operator<<(basic_ostream<char,traits>&, const signed char*);
-
-template<class traits>
-  basic_ostream<char,traits>& operator<<(basic_ostream<char,traits>&, const unsigned char*);
-
-// swap:
-template <class charT, class traits>
-  void swap(basic_ostream<charT, traits>& x, basic_ostream<charT, traits>& y);
-
-template <class charT, class traits>
-  basic_ostream<charT,traits>& endl(basic_ostream<charT,traits>& os);
-
-template <class charT, class traits>
-  basic_ostream<charT,traits>& ends(basic_ostream<charT,traits>& os);
-
-template <class charT, class traits>
-  basic_ostream<charT,traits>& flush(basic_ostream<charT,traits>& os);
-
-// rvalue stream insertion
-template <class Stream, class T>
-  Stream&& operator<<(Stream&& os, const T& x);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/ostream.syn.
 
 #include <__config>
 #include <bitset>
diff --git a/libcxx/include/queue b/libcxx/include/queue
--- a/libcxx/include/queue
+++ b/libcxx/include/queue
@@ -10,173 +10,7 @@
 #ifndef _LIBCPP_QUEUE
 #define _LIBCPP_QUEUE
 
-/*
-    queue synopsis
-
-namespace std
-{
-
-template <class T, class Container = deque<T>>
-class queue
-{
-public:
-    typedef Container                                container_type;
-    typedef typename container_type::value_type      value_type;
-    typedef typename container_type::reference       reference;
-    typedef typename container_type::const_reference const_reference;
-    typedef typename container_type::size_type       size_type;
-
-protected:
-    container_type c;
-
-public:
-    queue() = default;
-    ~queue() = default;
-
-    queue(const queue& q) = default;
-    queue(queue&& q) = default;
-
-    queue& operator=(const queue& q) = default;
-    queue& operator=(queue&& q) = default;
-
-    explicit queue(const container_type& c);
-    explicit queue(container_type&& c)
-    template <class Alloc>
-        explicit queue(const Alloc& a);
-    template <class Alloc>
-        queue(const container_type& c, const Alloc& a);
-    template <class Alloc>
-        queue(container_type&& c, const Alloc& a);
-    template <class Alloc>
-        queue(const queue& q, const Alloc& a);
-    template <class Alloc>
-        queue(queue&& q, const Alloc& a);
-
-    bool      empty() const;
-    size_type size() const;
-
-    reference       front();
-    const_reference front() const;
-    reference       back();
-    const_reference back() const;
-
-    void push(const value_type& v);
-    void push(value_type&& v);
-    template <class... Args> reference emplace(Args&&... args); // reference in C++17
-    void pop();
-
-    void swap(queue& q) noexcept(is_nothrow_swappable_v<Container>)
-};
-
-template<class Container>
-  queue(Container) -> queue<typename Container::value_type, Container>; // C++17
-
-template<class Container, class Allocator>
-  queue(Container, Allocator) -> queue<typename Container::value_type, Container>; // C++17
-
-template <class T, class Container>
-  bool operator==(const queue<T, Container>& x,const queue<T, Container>& y);
-
-template <class T, class Container>
-  bool operator< (const queue<T, Container>& x,const queue<T, Container>& y);
-
-template <class T, class Container>
-  bool operator!=(const queue<T, Container>& x,const queue<T, Container>& y);
-
-template <class T, class Container>
-  bool operator> (const queue<T, Container>& x,const queue<T, Container>& y);
-
-template <class T, class Container>
-  bool operator>=(const queue<T, Container>& x,const queue<T, Container>& y);
-
-template <class T, class Container>
-  bool operator<=(const queue<T, Container>& x,const queue<T, Container>& y);
-
-template <class T, class Container>
-  void swap(queue<T, Container>& x, queue<T, Container>& y)
-  noexcept(noexcept(x.swap(y)));
-
-template <class T, class Container = vector<T>,
-          class Compare = less<typename Container::value_type>>
-class priority_queue
-{
-public:
-    typedef Container                                container_type;
-    typedef typename container_type::value_type      value_type;
-    typedef typename container_type::reference       reference;
-    typedef typename container_type::const_reference const_reference;
-    typedef typename container_type::size_type       size_type;
-
-protected:
-    container_type c;
-    Compare comp;
-
-public:
-    priority_queue() : priority_queue(Compare()) {} // C++20
-    explicit priority_queue(const Compare& x) : priority_queue(x, Container()) {}
-    priority_queue(const Compare& x, const Container&);
-    explicit priority_queue(const Compare& x = Compare(), Container&&= Container()); // before C++20
-    priority_queue(const Compare& x, Container&&); // C++20
-    template <class InputIterator>
-        priority_queue(InputIterator first, InputIterator last,
-                       const Compare& comp = Compare());
-    template <class InputIterator>
-        priority_queue(InputIterator first, InputIterator last,
-                       const Compare& comp, const container_type& c);
-    template <class InputIterator>
-        priority_queue(InputIterator first, InputIterator last,
-                       const Compare& comp, container_type&& c);
-    template <class Alloc>
-        explicit priority_queue(const Alloc& a);
-    template <class Alloc>
-        priority_queue(const Compare& comp, const Alloc& a);
-    template <class Alloc>
-        priority_queue(const Compare& comp, const container_type& c,
-                       const Alloc& a);
-    template <class Alloc>
-        priority_queue(const Compare& comp, container_type&& c,
-                       const Alloc& a);
-    template <class Alloc>
-        priority_queue(const priority_queue& q, const Alloc& a);
-    template <class Alloc>
-        priority_queue(priority_queue&& q, const Alloc& a);
-
-    bool            empty() const;
-    size_type       size() const;
-    const_reference top() const;
-
-    void push(const value_type& v);
-    void push(value_type&& v);
-    template <class... Args> void emplace(Args&&... args);
-    void pop();
-
-    void swap(priority_queue& q)
-        noexcept(is_nothrow_swappable_v<Container> &&
-                 is_nothrow_swappable_v<Comp>)
-};
-
-template <class Compare, class Container>
-priority_queue(Compare, Container)
-    -> priority_queue<typename Container::value_type, Container, Compare>; // C++17
-
-template<class InputIterator,
-         class Compare = less<typename iterator_traits<InputIterator>::value_type>,
-         class Container = vector<typename iterator_traits<InputIterator>::value_type>>
-priority_queue(InputIterator, InputIterator, Compare = Compare(), Container = Container())
-    -> priority_queue<typename iterator_traits<InputIterator>::value_type, Container, Compare>; // C++17
-
-template<class Compare, class Container, class Allocator>
-priority_queue(Compare, Container, Allocator)
-    -> priority_queue<typename Container::value_type, Container, Compare>; // C++17
-
-template <class T, class Container, class Compare>
-  void swap(priority_queue<T, Container, Compare>& x,
-            priority_queue<T, Container, Compare>& y)
-            noexcept(noexcept(x.swap(y)));
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/queue.syn.
 
 #include <__config>
 #include <__utility/forward.h>
diff --git a/libcxx/include/random b/libcxx/include/random
--- a/libcxx/include/random
+++ b/libcxx/include/random
@@ -10,1672 +10,7 @@
 #ifndef _LIBCPP_RANDOM
 #define _LIBCPP_RANDOM
 
-/*
-    random synopsis
-
-#include <initializer_list>
-
-namespace std
-{
-// [rand.req.urng], uniform random bit generator requirements
-template<class G>
-concept uniform_random_bit_generator = see below; // C++20
-
-// Engines
-
-template <class UIntType, UIntType a, UIntType c, UIntType m>
-class linear_congruential_engine
-{
-public:
-    // types
-    typedef UIntType result_type;
-
-    // engine characteristics
-    static constexpr result_type multiplier = a;
-    static constexpr result_type increment = c;
-    static constexpr result_type modulus = m;
-    static constexpr result_type min() { return c == 0u ? 1u: 0u;}
-    static constexpr result_type max() { return m - 1u;}
-    static constexpr result_type default_seed = 1u;
-
-    // constructors and seeding functions
-    explicit linear_congruential_engine(result_type s = default_seed);         // before C++20
-    linear_congruential_engine() : linear_congruential_engine(default_seed) {} // C++20
-    explicit linear_congruential_engine(result_type s);                        // C++20
-    template<class Sseq> explicit linear_congruential_engine(Sseq& q);
-    void seed(result_type s = default_seed);
-    template<class Sseq> void seed(Sseq& q);
-
-    // generating functions
-    result_type operator()();
-    void discard(unsigned long long z);
-};
-
-template <class UIntType, UIntType a, UIntType c, UIntType m>
-bool
-operator==(const linear_congruential_engine<UIntType, a, c, m>& x,
-           const linear_congruential_engine<UIntType, a, c, m>& y);
-
-template <class UIntType, UIntType a, UIntType c, UIntType m>
-bool
-operator!=(const linear_congruential_engine<UIntType, a, c, m>& x,
-           const linear_congruential_engine<UIntType, a, c, m>& y);
-
-template <class charT, class traits,
-          class UIntType, UIntType a, UIntType c, UIntType m>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os,
-           const linear_congruential_engine<UIntType, a, c, m>& x);
-
-template <class charT, class traits,
-          class UIntType, UIntType a, UIntType c, UIntType m>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is,
-           linear_congruential_engine<UIntType, a, c, m>& x);
-
-template <class UIntType, size_t w, size_t n, size_t m, size_t r,
-          UIntType a, size_t u, UIntType d, size_t s,
-          UIntType b, size_t t, UIntType c, size_t l, UIntType f>
-class mersenne_twister_engine
-{
-public:
-    // types
-    typedef UIntType result_type;
-
-    // engine characteristics
-    static constexpr size_t word_size = w;
-    static constexpr size_t state_size = n;
-    static constexpr size_t shift_size = m;
-    static constexpr size_t mask_bits = r;
-    static constexpr result_type xor_mask = a;
-    static constexpr size_t tempering_u = u;
-    static constexpr result_type tempering_d = d;
-    static constexpr size_t tempering_s = s;
-    static constexpr result_type tempering_b = b;
-    static constexpr size_t tempering_t = t;
-    static constexpr result_type tempering_c = c;
-    static constexpr size_t tempering_l = l;
-    static constexpr result_type initialization_multiplier = f;
-    static constexpr result_type min () { return 0; }
-    static constexpr result_type max() { return 2^w - 1; }
-    static constexpr result_type default_seed = 5489u;
-
-    // constructors and seeding functions
-    explicit mersenne_twister_engine(result_type s = default_seed);      // before C++20
-    mersenne_twister_engine() : mersenne_twister_engine(default_seed) {} // C++20
-    explicit mersenne_twister_engine(result_type s);                     // C++20
-    template<class Sseq> explicit mersenne_twister_engine(Sseq& q);
-    void seed(result_type value = default_seed);
-    template<class Sseq> void seed(Sseq& q);
-
-    // generating functions
-    result_type operator()();
-    void discard(unsigned long long z);
-};
-
-template <class UIntType, size_t w, size_t n, size_t m, size_t r,
-          UIntType a, size_t u, UIntType d, size_t s,
-          UIntType b, size_t t, UIntType c, size_t l, UIntType f>
-bool
-operator==(
-    const mersenne_twister_engine<UIntType, w, n, m, r, a, u, d, s, b, t, c, l, f>& x,
-    const mersenne_twister_engine<UIntType, w, n, m, r, a, u, d, s, b, t, c, l, f>& y);
-
-template <class UIntType, size_t w, size_t n, size_t m, size_t r,
-          UIntType a, size_t u, UIntType d, size_t s,
-          UIntType b, size_t t, UIntType c, size_t l, UIntType f>
-bool
-operator!=(
-    const mersenne_twister_engine<UIntType, w, n, m, r, a, u, d, s, b, t, c, l, f>& x,
-    const mersenne_twister_engine<UIntType, w, n, m, r, a, u, d, s, b, t, c, l, f>& y);
-
-template <class charT, class traits,
-          class UIntType, size_t w, size_t n, size_t m, size_t r,
-          UIntType a, size_t u, UIntType d, size_t s,
-          UIntType b, size_t t, UIntType c, size_t l, UIntType f>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os,
-           const mersenne_twister_engine<UIntType, w, n, m, r, a, u, d, s, b, t, c, l, f>& x);
-
-template <class charT, class traits,
-          class UIntType, size_t w, size_t n, size_t m, size_t r,
-          UIntType a, size_t u, UIntType d, size_t s,
-          UIntType b, size_t t, UIntType c, size_t l, UIntType f>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is,
-           mersenne_twister_engine<UIntType, w, n, m, r, a, u, d, s, b, t, c, l, f>& x);
-
-template<class UIntType, size_t w, size_t s, size_t r>
-class subtract_with_carry_engine
-{
-public:
-    // types
-    typedef UIntType result_type;
-
-    // engine characteristics
-    static constexpr size_t word_size = w;
-    static constexpr size_t short_lag = s;
-    static constexpr size_t long_lag = r;
-    static constexpr result_type min() { return 0; }
-    static constexpr result_type max() { return m-1; }
-    static constexpr result_type default_seed = 19780503u;
-
-    // constructors and seeding functions
-    explicit subtract_with_carry_engine(result_type value = default_seed);     // before C++20
-    subtract_with_carry_engine() : subtract_with_carry_engine(default_seed) {} // C++20
-    explicit subtract_with_carry_engine(result_type value);                    // C++20
-    template<class Sseq> explicit subtract_with_carry_engine(Sseq& q);
-    void seed(result_type value = default_seed);
-    template<class Sseq> void seed(Sseq& q);
-
-    // generating functions
-    result_type operator()();
-    void discard(unsigned long long z);
-};
-
-template<class UIntType, size_t w, size_t s, size_t r>
-bool
-operator==(
-    const subtract_with_carry_engine<UIntType, w, s, r>& x,
-    const subtract_with_carry_engine<UIntType, w, s, r>& y);
-
-template<class UIntType, size_t w, size_t s, size_t r>
-bool
-operator!=(
-    const subtract_with_carry_engine<UIntType, w, s, r>& x,
-    const subtract_with_carry_engine<UIntType, w, s, r>& y);
-
-template <class charT, class traits,
-          class UIntType, size_t w, size_t s, size_t r>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os,
-           const subtract_with_carry_engine<UIntType, w, s, r>& x);
-
-template <class charT, class traits,
-          class UIntType, size_t w, size_t s, size_t r>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is,
-           subtract_with_carry_engine<UIntType, w, s, r>& x);
-
-template<class Engine, size_t p, size_t r>
-class discard_block_engine
-{
-public:
-    // types
-    typedef typename Engine::result_type result_type;
-
-    // engine characteristics
-    static constexpr size_t block_size = p;
-    static constexpr size_t used_block = r;
-    static constexpr result_type min() { return Engine::min(); }
-    static constexpr result_type max() { return Engine::max(); }
-
-    // constructors and seeding functions
-    discard_block_engine();
-    explicit discard_block_engine(const Engine& e);
-    explicit discard_block_engine(Engine&& e);
-    explicit discard_block_engine(result_type s);
-    template<class Sseq> explicit discard_block_engine(Sseq& q);
-    void seed();
-    void seed(result_type s);
-    template<class Sseq> void seed(Sseq& q);
-
-    // generating functions
-    result_type operator()();
-    void discard(unsigned long long z);
-
-    // property functions
-    const Engine& base() const noexcept;
-};
-
-template<class Engine, size_t p, size_t r>
-bool
-operator==(
-    const discard_block_engine<Engine, p, r>& x,
-    const discard_block_engine<Engine, p, r>& y);
-
-template<class Engine, size_t p, size_t r>
-bool
-operator!=(
-    const discard_block_engine<Engine, p, r>& x,
-    const discard_block_engine<Engine, p, r>& y);
-
-template <class charT, class traits,
-          class Engine, size_t p, size_t r>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os,
-           const discard_block_engine<Engine, p, r>& x);
-
-template <class charT, class traits,
-          class Engine, size_t p, size_t r>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is,
-           discard_block_engine<Engine, p, r>& x);
-
-template<class Engine, size_t w, class UIntType>
-class independent_bits_engine
-{
-public:
-    // types
-    typedef UIntType result_type;
-
-    // engine characteristics
-    static constexpr result_type min() { return 0; }
-    static constexpr result_type max() { return 2^w - 1; }
-
-    // constructors and seeding functions
-    independent_bits_engine();
-    explicit independent_bits_engine(const Engine& e);
-    explicit independent_bits_engine(Engine&& e);
-    explicit independent_bits_engine(result_type s);
-    template<class Sseq> explicit independent_bits_engine(Sseq& q);
-    void seed();
-    void seed(result_type s);
-    template<class Sseq> void seed(Sseq& q);
-
-    // generating functions
-    result_type operator()(); void discard(unsigned long long z);
-
-    // property functions
-    const Engine& base() const noexcept;
-};
-
-template<class Engine, size_t w, class UIntType>
-bool
-operator==(
-    const independent_bits_engine<Engine, w, UIntType>& x,
-    const independent_bits_engine<Engine, w, UIntType>& y);
-
-template<class Engine, size_t w, class UIntType>
-bool
-operator!=(
-    const independent_bits_engine<Engine, w, UIntType>& x,
-    const independent_bits_engine<Engine, w, UIntType>& y);
-
-template <class charT, class traits,
-          class Engine, size_t w, class UIntType>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os,
-           const independent_bits_engine<Engine, w, UIntType>& x);
-
-template <class charT, class traits,
-          class Engine, size_t w, class UIntType>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is,
-           independent_bits_engine<Engine, w, UIntType>& x);
-
-template<class Engine, size_t k>
-class shuffle_order_engine
-{
-public:
-    // types
-    typedef typename Engine::result_type result_type;
-
-    // engine characteristics
-    static constexpr size_t table_size = k;
-    static constexpr result_type min() { return Engine::min; }
-    static constexpr result_type max() { return Engine::max; }
-
-    // constructors and seeding functions
-    shuffle_order_engine();
-    explicit shuffle_order_engine(const Engine& e);
-    explicit shuffle_order_engine(Engine&& e);
-    explicit shuffle_order_engine(result_type s);
-    template<class Sseq> explicit shuffle_order_engine(Sseq& q);
-    void seed();
-    void seed(result_type s);
-    template<class Sseq> void seed(Sseq& q);
-
-    // generating functions
-    result_type operator()();
-    void discard(unsigned long long z);
-
-    // property functions
-    const Engine& base() const noexcept;
-};
-
-template<class Engine, size_t k>
-bool
-operator==(
-    const shuffle_order_engine<Engine, k>& x,
-    const shuffle_order_engine<Engine, k>& y);
-
-template<class Engine, size_t k>
-bool
-operator!=(
-    const shuffle_order_engine<Engine, k>& x,
-    const shuffle_order_engine<Engine, k>& y);
-
-template <class charT, class traits,
-          class Engine, size_t k>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os,
-           const shuffle_order_engine<Engine, k>& x);
-
-template <class charT, class traits,
-          class Engine, size_t k>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is,
-           shuffle_order_engine<Engine, k>& x);
-
-typedef linear_congruential_engine<uint_fast32_t, 16807, 0, 2147483647>
-                                                                   minstd_rand0;
-typedef linear_congruential_engine<uint_fast32_t, 48271, 0, 2147483647>
-                                                                    minstd_rand;
-typedef mersenne_twister_engine<uint_fast32_t, 32, 624, 397, 31,
-                                0x9908b0df,
-                                11, 0xffffffff,
-                                7,  0x9d2c5680,
-                                15, 0xefc60000,
-                                18, 1812433253>                         mt19937;
-typedef mersenne_twister_engine<uint_fast64_t, 64, 312, 156, 31,
-                                0xb5026f5aa96619e9,
-                                29, 0x5555555555555555,
-                                17, 0x71d67fffeda60000,
-                                37, 0xfff7eee000000000,
-                                43, 6364136223846793005>             mt19937_64;
-typedef subtract_with_carry_engine<uint_fast32_t, 24, 10, 24>     ranlux24_base;
-typedef subtract_with_carry_engine<uint_fast64_t, 48,  5, 12>     ranlux48_base;
-typedef discard_block_engine<ranlux24_base, 223, 23>                   ranlux24;
-typedef discard_block_engine<ranlux48_base, 389, 11>                   ranlux48;
-typedef shuffle_order_engine<minstd_rand0, 256>                         knuth_b;
-typedef minstd_rand                                       default_random_engine;
-
-// Generators
-
-class random_device
-{
-public:
-    // types
-    typedef unsigned int result_type;
-
-    // generator characteristics
-    static constexpr result_type min() { return numeric_limits<result_type>::min(); }
-    static constexpr result_type max() { return numeric_limits<result_type>::max(); }
-
-    // constructors
-    explicit random_device(const string& token = implementation-defined); // before C++20
-    random_device() : random_device(implementation-defined) {}            // C++20
-    explicit random_device(const string& token);                          // C++20
-
-    // generating functions
-    result_type operator()();
-
-    // property functions
-    double entropy() const noexcept;
-
-    // no copy functions
-    random_device(const random_device& ) = delete;
-    void operator=(const random_device& ) = delete;
-};
-
-// Utilities
-
-class seed_seq
-{
-public:
-    // types
-    typedef uint_least32_t result_type;
-
-    // constructors
-    seed_seq();
-    template<class T>
-        seed_seq(initializer_list<T> il);
-    template<class InputIterator>
-        seed_seq(InputIterator begin, InputIterator end);
-
-    // generating functions
-    template<class RandomAccessIterator>
-        void generate(RandomAccessIterator begin, RandomAccessIterator end);
-
-    // property functions
-    size_t size() const;
-    template<class OutputIterator>
-        void param(OutputIterator dest) const;
-
-    // no copy functions
-    seed_seq(const seed_seq&) = delete;
-    void operator=(const seed_seq& ) = delete;
-};
-
-template<class RealType, size_t bits, class URNG>
-    RealType generate_canonical(URNG& g);
-
-// Distributions
-
-template<class IntType = int>
-class uniform_int_distribution
-{
-public:
-    // types
-    typedef IntType result_type;
-
-    class param_type
-    {
-    public:
-        typedef uniform_int_distribution distribution_type;
-
-        explicit param_type(IntType a = 0,
-                                    IntType b = numeric_limits<IntType>::max());
-
-        result_type a() const;
-        result_type b() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit uniform_int_distribution(IntType a = 0,
-                                      IntType b = numeric_limits<IntType>::max()); // before C++20
-    uniform_int_distribution() : uniform_int_distribution(0) {}                    // C++20
-    explicit uniform_int_distribution(IntType a,
-                                      IntType b = numeric_limits<IntType>::max()); // C++20
-    explicit uniform_int_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type a() const;
-    result_type b() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const uniform_int_distribution& x,
-                           const uniform_int_distribution& y);
-    friend bool operator!=(const uniform_int_distribution& x,
-                           const uniform_int_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const uniform_int_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               uniform_int_distribution& x);
-};
-
-template<class RealType = double>
-class uniform_real_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef uniform_real_distribution distribution_type;
-
-        explicit param_type(RealType a = 0,
-                            RealType b = 1);
-
-        result_type a() const;
-        result_type b() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit uniform_real_distribution(RealType a = 0.0, RealType b = 1.0); // before C++20
-    uniform_real_distribution() : uniform_real_distribution(0.0) {}         // C++20
-    explicit uniform_real_distribution(RealType a, RealType b = 1.0);       // C++20
-    explicit uniform_real_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type a() const;
-    result_type b() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const uniform_real_distribution& x,
-                           const uniform_real_distribution& y);
-    friend bool operator!=(const uniform_real_distribution& x,
-                           const uniform_real_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const uniform_real_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               uniform_real_distribution& x);
-};
-
-class bernoulli_distribution
-{
-public:
-    // types
-    typedef bool result_type;
-
-    class param_type
-    {
-    public:
-        typedef bernoulli_distribution distribution_type;
-
-        explicit param_type(double p = 0.5);
-
-        double p() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit bernoulli_distribution(double p = 0.5);          // before C++20
-    bernoulli_distribution() : bernoulli_distribution(0.5) {} // C++20
-    explicit bernoulli_distribution(double p);                // C++20
-    explicit bernoulli_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    double p() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const bernoulli_distribution& x,
-                           const bernoulli_distribution& y);
-    friend bool operator!=(const bernoulli_distribution& x,
-                           const bernoulli_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const bernoulli_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               bernoulli_distribution& x);
-};
-
-template<class IntType = int>
-class binomial_distribution
-{
-public:
-    // types
-    typedef IntType result_type;
-
-    class param_type
-    {
-    public:
-        typedef binomial_distribution distribution_type;
-
-        explicit param_type(IntType t = 1, double p = 0.5);
-
-        IntType t() const;
-        double p() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit binomial_distribution(IntType t = 1, double p = 0.5); // before C++20
-    binomial_distribution() : binomial_distribution(1) {}          // C++20
-    explicit binomial_distribution(IntType t, double p = 0.5);     // C++20
-    explicit binomial_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    IntType t() const;
-    double p() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const binomial_distribution& x,
-                           const binomial_distribution& y);
-    friend bool operator!=(const binomial_distribution& x,
-                           const binomial_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const binomial_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               binomial_distribution& x);
-};
-
-template<class IntType = int>
-class geometric_distribution
-{
-public:
-    // types
-    typedef IntType result_type;
-
-    class param_type
-    {
-    public:
-        typedef geometric_distribution distribution_type;
-
-        explicit param_type(double p = 0.5);
-
-        double p() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit geometric_distribution(double p = 0.5);          // before C++20
-    geometric_distribution() : geometric_distribution(0.5) {} // C++20
-    explicit geometric_distribution(double p);                // C++20
-    explicit geometric_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    double p() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const geometric_distribution& x,
-                           const geometric_distribution& y);
-    friend bool operator!=(const geometric_distribution& x,
-                           const geometric_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const geometric_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               geometric_distribution& x);
-};
-
-template<class IntType = int>
-class negative_binomial_distribution
-{
-public:
-    // types
-    typedef IntType result_type;
-
-    class param_type
-    {
-    public:
-        typedef negative_binomial_distribution distribution_type;
-
-        explicit param_type(result_type k = 1, double p = 0.5);
-
-        result_type k() const;
-        double p() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit negative_binomial_distribution(IntType k = 1, double p = 0.5); // before C++20
-    negative_binomial_distribution() : negative_binomial_distribution(1) {} // C++20
-    explicit negative_binomial_distribution(IntType k, double p = 0.5);     // C++20
-    explicit negative_binomial_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type k() const;
-    double p() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const negative_binomial_distribution& x,
-                           const negative_binomial_distribution& y);
-    friend bool operator!=(const negative_binomial_distribution& x,
-                           const negative_binomial_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const negative_binomial_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               negative_binomial_distribution& x);
-};
-
-template<class IntType = int>
-class poisson_distribution
-{
-public:
-    // types
-    typedef IntType result_type;
-
-    class param_type
-    {
-    public:
-        typedef poisson_distribution distribution_type;
-
-        explicit param_type(double mean = 1.0);
-
-        double mean() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit poisson_distribution(double mean = 1.0);     // before C++20
-    poisson_distribution() : poisson_distribution(1.0) {} // C++20
-    explicit poisson_distribution(double mean);           // C++20
-    explicit poisson_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    double mean() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const poisson_distribution& x,
-                           const poisson_distribution& y);
-    friend bool operator!=(const poisson_distribution& x,
-                           const poisson_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const poisson_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               poisson_distribution& x);
-};
-
-template<class RealType = double>
-class exponential_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef exponential_distribution distribution_type;
-
-        explicit param_type(result_type lambda = 1.0);
-
-        result_type lambda() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit exponential_distribution(RealType lambda = 1.0);     // before C++20
-    exponential_distribution() : exponential_distribution(1.0) {} // C++20
-    explicit exponential_distribution(RealType lambda);           // C++20
-    explicit exponential_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type lambda() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const exponential_distribution& x,
-                           const exponential_distribution& y);
-    friend bool operator!=(const exponential_distribution& x,
-                           const exponential_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const exponential_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               exponential_distribution& x);
-};
-
-template<class RealType = double>
-class gamma_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef gamma_distribution distribution_type;
-
-        explicit param_type(result_type alpha = 1, result_type beta = 1);
-
-        result_type alpha() const;
-        result_type beta() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit gamma_distribution(RealType alpha = 0.0, RealType beta = 1.0); // before C++20
-    gamma_distribution() : gamma_distribution(0.0) {}                       // C++20
-    explicit gamma_distribution(RealType alpha, RealType beta = 1.0);       // C++20
-    explicit gamma_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type alpha() const;
-    result_type beta() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const gamma_distribution& x,
-                           const gamma_distribution& y);
-    friend bool operator!=(const gamma_distribution& x,
-                           const gamma_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const gamma_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               gamma_distribution& x);
-};
-
-template<class RealType = double>
-class weibull_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef weibull_distribution distribution_type;
-
-        explicit param_type(result_type alpha = 1, result_type beta = 1);
-
-        result_type a() const;
-        result_type b() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit weibull_distribution(RealType a = 1.0, RealType b = 1.0); // before C++20
-    weibull_distribution() : weibull_distribution(1.0) {}              // C++20
-    explicit weibull_distribution(RealType a, RealType b = 1.0);       // C++20
-    explicit weibull_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type a() const;
-    result_type b() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const weibull_distribution& x,
-                           const weibull_distribution& y);
-    friend bool operator!=(const weibull_distribution& x,
-                           const weibull_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const weibull_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               weibull_distribution& x);
-};
-
-template<class RealType = double>
-class extreme_value_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef extreme_value_distribution distribution_type;
-
-        explicit param_type(result_type a = 0, result_type b = 1);
-
-        result_type a() const;
-        result_type b() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit extreme_value_distribution(RealType a = 0.0, RealType b = 1.0); // before C++20
-    extreme_value_distribution() : extreme_value_distribution(0.0) {}        // C++20
-    explicit extreme_value_distribution(RealType a, RealType b = 1.0);       // C++20
-    explicit extreme_value_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type a() const;
-    result_type b() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const extreme_value_distribution& x,
-                           const extreme_value_distribution& y);
-    friend bool operator!=(const extreme_value_distribution& x,
-                           const extreme_value_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const extreme_value_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               extreme_value_distribution& x);
-};
-
-template<class RealType = double>
-class normal_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef normal_distribution distribution_type;
-
-        explicit param_type(result_type mean = 0, result_type stddev = 1);
-
-        result_type mean() const;
-        result_type stddev() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructors and reset functions
-    explicit normal_distribution(RealType mean = 0.0, RealType stddev = 1.0); // before C++20
-    normal_distribution() : normal_distribution(0.0) {}                       // C++20
-    explicit normal_distribution(RealType mean, RealType stddev = 1.0);       // C++20
-    explicit normal_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type mean() const;
-    result_type stddev() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const normal_distribution& x,
-                           const normal_distribution& y);
-    friend bool operator!=(const normal_distribution& x,
-                           const normal_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const normal_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               normal_distribution& x);
-};
-
-template<class RealType = double>
-class lognormal_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef lognormal_distribution distribution_type;
-
-        explicit param_type(result_type m = 0, result_type s = 1);
-
-        result_type m() const;
-        result_type s() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit lognormal_distribution(RealType mean = 0.0, RealType stddev = 1.0); // before C++20
-    lognormal_distribution() : lognormal_distribution(0.0) {}                    // C++20
-    explicit lognormal_distribution(RealType mean, RealType stddev = 1.0);       // C++20
-    explicit lognormal_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type m() const;
-    result_type s() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const lognormal_distribution& x,
-                           const lognormal_distribution& y);
-    friend bool operator!=(const lognormal_distribution& x,
-                           const lognormal_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const lognormal_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               lognormal_distribution& x);
-};
-
-template<class RealType = double>
-class chi_squared_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef chi_squared_distribution distribution_type;
-
-        explicit param_type(result_type n = 1);
-
-        result_type n() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit chi_squared_distribution(RealType n = 1.0);          // before C++20
-    chi_squared_distribution() : chi_squared_distribution(1.0) {} // C++20
-    explicit chi_squared_distribution(RealType n);                // C++20
-    explicit chi_squared_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type n() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const chi_squared_distribution& x,
-                           const chi_squared_distribution& y);
-    friend bool operator!=(const chi_squared_distribution& x,
-                           const chi_squared_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const chi_squared_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               chi_squared_distribution& x);
-};
-
-template<class RealType = double>
-class cauchy_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef cauchy_distribution distribution_type;
-
-        explicit param_type(result_type a = 0, result_type b = 1);
-
-        result_type a() const;
-        result_type b() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit cauchy_distribution(RealType a = 0.0, RealType b = 1.0); // before C++20
-    cauchy_distribution() : cauchy_distribution(0.0) {}               // C++20
-    explicit cauchy_distribution(RealType a, RealType b = 1.0);       // C++20
-    explicit cauchy_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type a() const;
-    result_type b() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const cauchy_distribution& x,
-                           const cauchy_distribution& y);
-    friend bool operator!=(const cauchy_distribution& x,
-                           const cauchy_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const cauchy_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               cauchy_distribution& x);
-};
-
-template<class RealType = double>
-class fisher_f_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef fisher_f_distribution distribution_type;
-
-        explicit param_type(result_type m = 1, result_type n = 1);
-
-        result_type m() const;
-        result_type n() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit fisher_f_distribution(RealType m = 1.0, RealType n = 1.0); // before C++20
-    fisher_f_distribution() : fisher_f_distribution(1.0) {}             // C++20
-    explicit fisher_f_distribution(RealType m, RealType n = 1.0);       // C++20
-    explicit fisher_f_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type m() const;
-    result_type n() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const fisher_f_distribution& x,
-                           const fisher_f_distribution& y);
-    friend bool operator!=(const fisher_f_distribution& x,
-                           const fisher_f_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const fisher_f_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               fisher_f_distribution& x);
-};
-
-template<class RealType = double>
-class student_t_distribution
-{
-public:
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef student_t_distribution distribution_type;
-
-        explicit param_type(result_type n = 1);
-
-        result_type n() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    explicit student_t_distribution(RealType n = 1.0);        // before C++20
-    student_t_distribution() : student_t_distribution(1.0) {} // C++20
-    explicit student_t_distribution(RealType n);              // C++20
-    explicit student_t_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    result_type n() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const student_t_distribution& x,
-                           const student_t_distribution& y);
-    friend bool operator!=(const student_t_distribution& x,
-                           const student_t_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const student_t_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               student_t_distribution& x);
-};
-
-template<class IntType = int>
-class discrete_distribution
-{
-public:
-    // types
-    typedef IntType result_type;
-
-    class param_type
-    {
-    public:
-        typedef discrete_distribution distribution_type;
-
-        param_type();
-        template<class InputIterator>
-            param_type(InputIterator firstW, InputIterator lastW);
-        param_type(initializer_list<double> wl);
-        template<class UnaryOperation>
-            param_type(size_t nw, double xmin, double xmax, UnaryOperation fw);
-
-        vector<double> probabilities() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    discrete_distribution();
-    template<class InputIterator>
-        discrete_distribution(InputIterator firstW, InputIterator lastW);
-    discrete_distribution(initializer_list<double> wl);
-    template<class UnaryOperation>
-        discrete_distribution(size_t nw, double xmin, double xmax,
-                              UnaryOperation fw);
-    explicit discrete_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    vector<double> probabilities() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const discrete_distribution& x,
-                           const discrete_distribution& y);
-    friend bool operator!=(const discrete_distribution& x,
-                           const discrete_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const discrete_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               discrete_distribution& x);
-};
-
-template<class RealType = double>
-class piecewise_constant_distribution
-{
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef piecewise_constant_distribution distribution_type;
-
-        param_type();
-        template<class InputIteratorB, class InputIteratorW>
-            param_type(InputIteratorB firstB, InputIteratorB lastB,
-                       InputIteratorW firstW);
-        template<class UnaryOperation>
-            param_type(initializer_list<result_type> bl, UnaryOperation fw);
-        template<class UnaryOperation>
-            param_type(size_t nw, result_type xmin, result_type xmax,
-                       UnaryOperation fw);
-
-        vector<result_type> intervals() const;
-        vector<result_type> densities() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    piecewise_constant_distribution();
-    template<class InputIteratorB, class InputIteratorW>
-        piecewise_constant_distribution(InputIteratorB firstB,
-                                        InputIteratorB lastB,
-                                        InputIteratorW firstW);
-    template<class UnaryOperation>
-        piecewise_constant_distribution(initializer_list<result_type> bl,
-                                        UnaryOperation fw);
-    template<class UnaryOperation>
-        piecewise_constant_distribution(size_t nw, result_type xmin,
-                                        result_type xmax, UnaryOperation fw);
-    explicit piecewise_constant_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    vector<result_type> intervals() const;
-    vector<result_type> densities() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const piecewise_constant_distribution& x,
-                           const piecewise_constant_distribution& y);
-    friend bool operator!=(const piecewise_constant_distribution& x,
-                           const piecewise_constant_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const piecewise_constant_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               piecewise_constant_distribution& x);
-};
-
-template<class RealType = double>
-class piecewise_linear_distribution
-{
-    // types
-    typedef RealType result_type;
-
-    class param_type
-    {
-    public:
-        typedef piecewise_linear_distribution distribution_type;
-
-        param_type();
-        template<class InputIteratorB, class InputIteratorW>
-            param_type(InputIteratorB firstB, InputIteratorB lastB,
-                       InputIteratorW firstW);
-        template<class UnaryOperation>
-            param_type(initializer_list<result_type> bl, UnaryOperation fw);
-        template<class UnaryOperation>
-            param_type(size_t nw, result_type xmin, result_type xmax,
-                       UnaryOperation fw);
-
-        vector<result_type> intervals() const;
-        vector<result_type> densities() const;
-
-        friend bool operator==(const param_type& x, const param_type& y);
-        friend bool operator!=(const param_type& x, const param_type& y);
-    };
-
-    // constructor and reset functions
-    piecewise_linear_distribution();
-    template<class InputIteratorB, class InputIteratorW>
-        piecewise_linear_distribution(InputIteratorB firstB,
-                                      InputIteratorB lastB,
-                                      InputIteratorW firstW);
-
-    template<class UnaryOperation>
-        piecewise_linear_distribution(initializer_list<result_type> bl,
-                                      UnaryOperation fw);
-
-    template<class UnaryOperation>
-        piecewise_linear_distribution(size_t nw, result_type xmin,
-                                      result_type xmax, UnaryOperation fw);
-
-    explicit piecewise_linear_distribution(const param_type& parm);
-    void reset();
-
-    // generating functions
-    template<class URNG> result_type operator()(URNG& g);
-    template<class URNG> result_type operator()(URNG& g, const param_type& parm);
-
-    // property functions
-    vector<result_type> intervals() const;
-    vector<result_type> densities() const;
-
-    param_type param() const;
-    void param(const param_type& parm);
-
-    result_type min() const;
-    result_type max() const;
-
-    friend bool operator==(const piecewise_linear_distribution& x,
-                           const piecewise_linear_distribution& y);
-    friend bool operator!=(const piecewise_linear_distribution& x,
-                           const piecewise_linear_distribution& y);
-
-    template <class charT, class traits>
-    friend
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os,
-               const piecewise_linear_distribution& x);
-
-    template <class charT, class traits>
-    friend
-    basic_istream<charT, traits>&
-    operator>>(basic_istream<charT, traits>& is,
-               piecewise_linear_distribution& x);
-};
-
-} // std
-*/
+// Synopsis avaiable at http://wg21.link/rand.synopsis.
 
 #include <__config>
 #include <__random/uniform_int_distribution.h>
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -10,100 +10,7 @@
 #ifndef _LIBCPP_RANGES
 #define _LIBCPP_RANGES
 
-/*
-
-#include <compare>              // see [compare.syn]
-#include <initializer_list>     // see [initializer.list.syn]
-#include <iterator>             // see [iterator.synopsis]
-
-namespace std::ranges {
-  inline namespace unspecified {
-    // [range.access], range access
-    inline constexpr unspecified begin = unspecified;
-    inline constexpr unspecified end = unspecified;
-    inline constexpr unspecified cbegin = unspecified;
-    inline constexpr unspecified cend = unspecified;
-
-    inline constexpr unspecified size = unspecified;
-    inline constexpr unspecified ssize = unspecified;
-  }
-
-  // [range.range], ranges
-  template<class T>
-    concept range = see below;
-
-  template<class T>
-    inline constexpr bool enable_borrowed_range = false;
-
-  template<class T>
-    using iterator_t = decltype(ranges::begin(declval<T&>()));
-  template<class T>
-    using iterator_t = decltype(ranges::begin(declval<T&>()));
-  template<range R>
-    using sentinel_t = decltype(ranges::end(declval<R&>()));
-  template<range R>
-    using range_difference_t = iter_difference_t<iterator_t<R>>;
-  template<range R>
-    using range_value_t = iter_value_t<iterator_t<R>>;
-  template<range R>
-    using range_reference_t = iter_reference_t<iterator_t<R>>;
-  template<range R>
-    using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<R>>;
-
-  // [range.sized]
-  template<class>
-    inline constexpr bool disable_sized_range = false;
-
-  template<class T>
-    concept sized_range = ...;
-
-  // [range.view], views
-  template<class T>
-    inline constexpr bool enable_view = ...;
-
-  struct view_base { };
-
-  template<class T>
-    concept view = ...;
-
-  // [range.refinements], other range refinements
-  template<class T>
-    concept input_range = see below;
-
-  template<class T>
-    concept forward_range = see below;
-
-  template<class T>
-  concept bidirectional_range = see below;
-
-  template<class T>
-  concept random_access_range = see below;
-
-  template<class T>
-  concept contiguous_range = see below;
-
-  template <class _Tp>
-    concept common_range = see below;
-
-  // [view.interface], class template view_interface
-  template<class D>
-    requires is_class_v<D> && same_as<D, remove_cv_t<D>>
-  class view_interface;
-
-  // [range.empty], empty view
-  template<class T>
-    requires is_object_v<T>
-  class empty_view;
-
-  // [range.drop], drop view
-  template<view V>
-    class drop_view;
-
-  template<class T>
-    inline constexpr bool enable_borrowed_range<drop_view<T>> = enable_borrowed_range<T>;
-}
-
-*/
+// Synopsis avaiable at http://wg21.link/ranges.syn.
 
 #include <__config>
 #include <__ranges/access.h>
diff --git a/libcxx/include/ratio b/libcxx/include/ratio
--- a/libcxx/include/ratio
+++ b/libcxx/include/ratio
@@ -10,72 +10,7 @@
 #ifndef _LIBCPP_RATIO
 #define _LIBCPP_RATIO
 
-/*
-    ratio synopsis
-
-namespace std
-{
-
-template <intmax_t N, intmax_t D = 1>
-class ratio
-{
-public:
-    static constexpr intmax_t num;
-    static constexpr intmax_t den;
-    typedef ratio<num, den> type;
-};
-
-// ratio arithmetic
-template <class R1, class R2> using ratio_add = ...;
-template <class R1, class R2> using ratio_subtract = ...;
-template <class R1, class R2> using ratio_multiply = ...;
-template <class R1, class R2> using ratio_divide = ...;
-
-// ratio comparison
-template <class R1, class R2> struct ratio_equal;
-template <class R1, class R2> struct ratio_not_equal;
-template <class R1, class R2> struct ratio_less;
-template <class R1, class R2> struct ratio_less_equal;
-template <class R1, class R2> struct ratio_greater;
-template <class R1, class R2> struct ratio_greater_equal;
-
-// convenience SI typedefs
-typedef ratio<1, 1000000000000000000000000> yocto;  // not supported
-typedef ratio<1,    1000000000000000000000> zepto;  // not supported
-typedef ratio<1,       1000000000000000000> atto;
-typedef ratio<1,          1000000000000000> femto;
-typedef ratio<1,             1000000000000> pico;
-typedef ratio<1,                1000000000> nano;
-typedef ratio<1,                   1000000> micro;
-typedef ratio<1,                      1000> milli;
-typedef ratio<1,                       100> centi;
-typedef ratio<1,                        10> deci;
-typedef ratio<                       10, 1> deca;
-typedef ratio<                      100, 1> hecto;
-typedef ratio<                     1000, 1> kilo;
-typedef ratio<                  1000000, 1> mega;
-typedef ratio<               1000000000, 1> giga;
-typedef ratio<            1000000000000, 1> tera;
-typedef ratio<         1000000000000000, 1> peta;
-typedef ratio<      1000000000000000000, 1> exa;
-typedef ratio<   1000000000000000000000, 1> zetta;  // not supported
-typedef ratio<1000000000000000000000000, 1> yotta;  // not supported
-
-  // 20.11.5, ratio comparison
-  template <class R1, class R2> inline constexpr bool ratio_equal_v
-    = ratio_equal<R1, R2>::value;                                       // C++17
-  template <class R1, class R2> inline constexpr bool ratio_not_equal_v
-    = ratio_not_equal<R1, R2>::value;                                   // C++17
-  template <class R1, class R2> inline constexpr bool ratio_less_v
-    = ratio_less<R1, R2>::value;                                        // C++17
-  template <class R1, class R2> inline constexpr bool ratio_less_equal_v
-    = ratio_less_equal<R1, R2>::value;                                  // C++17
-  template <class R1, class R2> inline constexpr bool ratio_greater_v
-    = ratio_greater<R1, R2>::value;                                     // C++17
-  template <class R1, class R2> inline constexpr bool ratio_greater_equal_v
-    = ratio_greater_equal<R1, R2>::value;                               // C++17
-}
-*/
+// Synopsis avaiable at http://wg21.link/ratio.syn.
 
 #include <__config>
 #include <climits>
diff --git a/libcxx/include/regex b/libcxx/include/regex
--- a/libcxx/include/regex
+++ b/libcxx/include/regex
@@ -10,757 +10,7 @@
 #ifndef _LIBCPP_REGEX
 #define _LIBCPP_REGEX
 
-/*
-    regex synopsis
-
-#include <initializer_list>
-
-namespace std
-{
-
-namespace regex_constants
-{
-
-enum syntax_option_type
-{
-    icase      = unspecified,
-    nosubs     = unspecified,
-    optimize   = unspecified,
-    collate    = unspecified,
-    ECMAScript = unspecified,
-    basic      = unspecified,
-    extended   = unspecified,
-    awk        = unspecified,
-    grep       = unspecified,
-    egrep      = unspecified,
-    multiline  = unspecified
-};
-
-constexpr syntax_option_type operator~(syntax_option_type f);
-constexpr syntax_option_type operator&(syntax_option_type lhs, syntax_option_type rhs);
-constexpr syntax_option_type operator|(syntax_option_type lhs, syntax_option_type rhs);
-
-enum match_flag_type
-{
-    match_default     = 0,
-    match_not_bol     = unspecified,
-    match_not_eol     = unspecified,
-    match_not_bow     = unspecified,
-    match_not_eow     = unspecified,
-    match_any         = unspecified,
-    match_not_null    = unspecified,
-    match_continuous  = unspecified,
-    match_prev_avail  = unspecified,
-    format_default    = 0,
-    format_sed        = unspecified,
-    format_no_copy    = unspecified,
-    format_first_only = unspecified
-};
-
-constexpr match_flag_type operator~(match_flag_type f);
-constexpr match_flag_type operator&(match_flag_type lhs, match_flag_type rhs);
-constexpr match_flag_type operator|(match_flag_type lhs, match_flag_type rhs);
-
-enum error_type
-{
-    error_collate    = unspecified,
-    error_ctype      = unspecified,
-    error_escape     = unspecified,
-    error_backref    = unspecified,
-    error_brack      = unspecified,
-    error_paren      = unspecified,
-    error_brace      = unspecified,
-    error_badbrace   = unspecified,
-    error_range      = unspecified,
-    error_space      = unspecified,
-    error_badrepeat  = unspecified,
-    error_complexity = unspecified,
-    error_stack      = unspecified
-};
-
-}  // regex_constants
-
-class regex_error
-    : public runtime_error
-{
-public:
-    explicit regex_error(regex_constants::error_type ecode);
-    regex_constants::error_type code() const;
-};
-
-template <class charT>
-struct regex_traits
-{
-public:
-    typedef charT                   char_type;
-    typedef basic_string<char_type> string_type;
-    typedef locale                  locale_type;
-    typedef /bitmask_type/          char_class_type;
-
-    regex_traits();
-
-    static size_t length(const char_type* p);
-    charT translate(charT c) const;
-    charT translate_nocase(charT c) const;
-    template <class ForwardIterator>
-        string_type
-        transform(ForwardIterator first, ForwardIterator last) const;
-    template <class ForwardIterator>
-        string_type
-        transform_primary( ForwardIterator first, ForwardIterator last) const;
-    template <class ForwardIterator>
-        string_type
-        lookup_collatename(ForwardIterator first, ForwardIterator last) const;
-    template <class ForwardIterator>
-        char_class_type
-        lookup_classname(ForwardIterator first, ForwardIterator last,
-                         bool icase = false) const;
-    bool isctype(charT c, char_class_type f) const;
-    int value(charT ch, int radix) const;
-    locale_type imbue(locale_type l);
-    locale_type getloc()const;
-};
-
-template <class charT, class traits = regex_traits<charT>>
-class basic_regex
-{
-public:
-    // types:
-    typedef charT                               value_type;
-    typedef traits                              traits_type;
-    typedef typename traits::string_type        string_type;
-    typedef regex_constants::syntax_option_type flag_type;
-    typedef typename traits::locale_type        locale_type;
-
-    // constants:
-    static constexpr regex_constants::syntax_option_type icase = regex_constants::icase;
-    static constexpr regex_constants::syntax_option_type nosubs = regex_constants::nosubs;
-    static constexpr regex_constants::syntax_option_type optimize = regex_constants::optimize;
-    static constexpr regex_constants::syntax_option_type collate = regex_constants::collate;
-    static constexpr regex_constants::syntax_option_type ECMAScript = regex_constants::ECMAScript;
-    static constexpr regex_constants::syntax_option_type basic = regex_constants::basic;
-    static constexpr regex_constants::syntax_option_type extended = regex_constants::extended;
-    static constexpr regex_constants::syntax_option_type awk = regex_constants::awk;
-    static constexpr regex_constants::syntax_option_type grep = regex_constants::grep;
-    static constexpr regex_constants::syntax_option_type egrep = regex_constants::egrep;
-    static constexpr regex_constants::syntax_option_type multiline = regex_constants::multiline;
-
-    // construct/copy/destroy:
-    basic_regex();
-    explicit basic_regex(const charT* p, flag_type f = regex_constants::ECMAScript);
-    basic_regex(const charT* p, size_t len, flag_type f = regex_constants::ECMAScript);
-    basic_regex(const basic_regex&);
-    basic_regex(basic_regex&&) noexcept;
-    template <class ST, class SA>
-        explicit basic_regex(const basic_string<charT, ST, SA>& p,
-                             flag_type f = regex_constants::ECMAScript);
-    template <class ForwardIterator>
-        basic_regex(ForwardIterator first, ForwardIterator last,
-                    flag_type f = regex_constants::ECMAScript);
-    basic_regex(initializer_list<charT>, flag_type = regex_constants::ECMAScript);
-
-    ~basic_regex();
-
-    basic_regex& operator=(const basic_regex&);
-    basic_regex& operator=(basic_regex&&) noexcept;
-    basic_regex& operator=(const charT* ptr);
-    basic_regex& operator=(initializer_list<charT> il);
-    template <class ST, class SA>
-        basic_regex& operator=(const basic_string<charT, ST, SA>& p);
-
-    // assign:
-    basic_regex& assign(const basic_regex& that);
-    basic_regex& assign(basic_regex&& that) noexcept;
-    basic_regex& assign(const charT* ptr,           flag_type f = regex_constants::ECMAScript);
-    basic_regex& assign(const charT* p, size_t len, flag_type f = regex_constants::ECMAScript);
-    template <class string_traits, class A>
-        basic_regex& assign(const basic_string<charT, string_traits, A>& s,
-                                                    flag_type f = regex_constants::ECMAScript);
-    template <class InputIterator>
-        basic_regex& assign(InputIterator first, InputIterator last,
-                                                    flag_type f = regex_constants::ECMAScript);
-    basic_regex& assign(initializer_list<charT>,    flag_type f = regex_constants::ECMAScript);
-
-    // const operations:
-    unsigned mark_count() const;
-    flag_type flags() const;
-
-    // locale:
-    locale_type imbue(locale_type loc);
-    locale_type getloc() const;
-
-    // swap:
-    void swap(basic_regex&);
-};
-
-template<class ForwardIterator>
-basic_regex(ForwardIterator, ForwardIterator,
-            regex_constants::syntax_option_type = regex_constants::ECMAScript)
-    -> basic_regex<typename iterator_traits<ForwardIterator>::value_type>; // C++17
-
-typedef basic_regex<char>    regex;
-typedef basic_regex<wchar_t> wregex;
-
-template <class charT, class traits>
-    void swap(basic_regex<charT, traits>& e1, basic_regex<charT, traits>& e2);
-
-template <class BidirectionalIterator>
-class sub_match
-    : public pair<BidirectionalIterator, BidirectionalIterator>
-{
-public:
-    typedef typename iterator_traits<BidirectionalIterator>::value_type value_type;
-    typedef typename iterator_traits<BidirectionalIterator>::difference_type difference_type;
-    typedef BidirectionalIterator                                      iterator;
-    typedef basic_string<value_type>                                string_type;
-
-    bool matched;
-
-    constexpr sub_match();
-
-    difference_type length() const;
-    operator string_type() const;
-    string_type str() const;
-
-    int compare(const sub_match& s) const;
-    int compare(const string_type& s) const;
-    int compare(const value_type* s) const;
-};
-
-typedef sub_match<const char*>             csub_match;
-typedef sub_match<const wchar_t*>          wcsub_match;
-typedef sub_match<string::const_iterator>  ssub_match;
-typedef sub_match<wstring::const_iterator> wssub_match;
-
-template <class BiIter>
-    bool
-    operator==(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator!=(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator<(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator<=(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator>=(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator>(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator==(const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator!=(const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator<(const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& lhs,
-              const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator>(const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& lhs,
-              const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool operator>=(const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& lhs,
-                    const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator<=(const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator==(const sub_match<BiIter>& lhs,
-               const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator!=(const sub_match<BiIter>& lhs,
-               const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator<(const sub_match<BiIter>& lhs,
-              const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool operator>(const sub_match<BiIter>& lhs,
-                   const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator>=(const sub_match<BiIter>& lhs,
-               const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& rhs);
-
-template <class BiIter, class ST, class SA>
-    bool
-    operator<=(const sub_match<BiIter>& lhs,
-               const basic_string<typename iterator_traits<BiIter>::value_type, ST, SA>& rhs);
-
-template <class BiIter>
-    bool
-    operator==(typename iterator_traits<BiIter>::value_type const* lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator!=(typename iterator_traits<BiIter>::value_type const* lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator<(typename iterator_traits<BiIter>::value_type const* lhs,
-              const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator>(typename iterator_traits<BiIter>::value_type const* lhs,
-              const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator>=(typename iterator_traits<BiIter>::value_type const* lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator<=(typename iterator_traits<BiIter>::value_type const* lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator==(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const* rhs);
-
-template <class BiIter>
-    bool
-    operator!=(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const* rhs);
-
-template <class BiIter>
-    bool
-    operator<(const sub_match<BiIter>& lhs,
-              typename iterator_traits<BiIter>::value_type const* rhs);
-
-template <class BiIter>
-    bool
-    operator>(const sub_match<BiIter>& lhs,
-              typename iterator_traits<BiIter>::value_type const* rhs);
-
-template <class BiIter>
-    bool
-    operator>=(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const* rhs);
-
-template <class BiIter>
-    bool
-    operator<=(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const* rhs);
-
-template <class BiIter>
-    bool
-    operator==(typename iterator_traits<BiIter>::value_type const& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator!=(typename iterator_traits<BiIter>::value_type const& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator<(typename iterator_traits<BiIter>::value_type const& lhs,
-              const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator>(typename iterator_traits<BiIter>::value_type const& lhs,
-              const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator>=(typename iterator_traits<BiIter>::value_type const& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator<=(typename iterator_traits<BiIter>::value_type const& lhs,
-               const sub_match<BiIter>& rhs);
-
-template <class BiIter>
-    bool
-    operator==(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const& rhs);
-
-template <class BiIter>
-    bool
-    operator!=(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const& rhs);
-
-template <class BiIter>
-    bool
-    operator<(const sub_match<BiIter>& lhs,
-              typename iterator_traits<BiIter>::value_type const& rhs);
-
-template <class BiIter>
-    bool
-    operator>(const sub_match<BiIter>& lhs,
-              typename iterator_traits<BiIter>::value_type const& rhs);
-
-template <class BiIter>
-    bool
-    operator>=(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const& rhs);
-
-template <class BiIter>
-    bool
-    operator<=(const sub_match<BiIter>& lhs,
-               typename iterator_traits<BiIter>::value_type const& rhs);
-
-template <class charT, class ST, class BiIter>
-    basic_ostream<charT, ST>&
-    operator<<(basic_ostream<charT, ST>& os, const sub_match<BiIter>& m);
-
-template <class BidirectionalIterator,
-          class Allocator = allocator<sub_match<BidirectionalIterator>>>
-class match_results
-{
-public:
-    typedef sub_match<BidirectionalIterator>                  value_type;
-    typedef const value_type&                                 const_reference;
-    typedef value_type&                                       reference;
-    typedef /implementation-defined/                          const_iterator;
-    typedef const_iterator                                    iterator;
-    typedef typename iterator_traits<BidirectionalIterator>::difference_type difference_type;
-    typedef typename allocator_traits<Allocator>::size_type   size_type;
-    typedef Allocator                                         allocator_type;
-    typedef typename iterator_traits<BidirectionalIterator>::value_type char_type;
-    typedef basic_string<char_type>                           string_type;
-
-    // construct/copy/destroy:
-    explicit match_results(const Allocator& a = Allocator()); // before C++20
-    match_results() : match_results(Allocator()) {}           // C++20
-    explicit match_results(const Allocator& a);               // C++20
-    match_results(const match_results& m);
-    match_results(match_results&& m) noexcept;
-    match_results& operator=(const match_results& m);
-    match_results& operator=(match_results&& m);
-    ~match_results();
-
-    bool ready() const;
-
-    // size:
-    size_type size() const;
-    size_type max_size() const;
-    bool empty() const;
-
-    // element access:
-    difference_type length(size_type sub = 0) const;
-    difference_type position(size_type sub = 0) const;
-    string_type str(size_type sub = 0) const;
-    const_reference operator[](size_type n) const;
-
-    const_reference prefix() const;
-    const_reference suffix() const;
-
-    const_iterator begin() const;
-    const_iterator end() const;
-    const_iterator cbegin() const;
-    const_iterator cend() const;
-
-    // format:
-    template <class OutputIter>
-        OutputIter
-        format(OutputIter out, const char_type* fmt_first,
-               const char_type* fmt_last,
-               regex_constants::match_flag_type flags = regex_constants::format_default) const;
-    template <class OutputIter, class ST, class SA>
-        OutputIter
-        format(OutputIter out, const basic_string<char_type, ST, SA>& fmt,
-               regex_constants::match_flag_type flags = regex_constants::format_default) const;
-    template <class ST, class SA>
-        basic_string<char_type, ST, SA>
-        format(const basic_string<char_type, ST, SA>& fmt,
-               regex_constants::match_flag_type flags = regex_constants::format_default) const;
-    string_type
-        format(const char_type* fmt,
-               regex_constants::match_flag_type flags = regex_constants::format_default) const;
-
-    // allocator:
-    allocator_type get_allocator() const;
-
-    // swap:
-    void swap(match_results& that);
-};
-
-typedef match_results<const char*>             cmatch;
-typedef match_results<const wchar_t*>          wcmatch;
-typedef match_results<string::const_iterator>  smatch;
-typedef match_results<wstring::const_iterator> wsmatch;
-
-template <class BidirectionalIterator, class Allocator>
-    bool
-    operator==(const match_results<BidirectionalIterator, Allocator>& m1,
-               const match_results<BidirectionalIterator, Allocator>& m2);
-
-template <class BidirectionalIterator, class Allocator>
-    bool
-    operator!=(const match_results<BidirectionalIterator, Allocator>& m1,
-               const match_results<BidirectionalIterator, Allocator>& m2);
-
-template <class BidirectionalIterator, class Allocator>
-    void
-    swap(match_results<BidirectionalIterator, Allocator>& m1,
-         match_results<BidirectionalIterator, Allocator>& m2);
-
-template <class BidirectionalIterator, class Allocator, class charT, class traits>
-    bool
-    regex_match(BidirectionalIterator first, BidirectionalIterator last,
-                match_results<BidirectionalIterator, Allocator>& m,
-                const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class BidirectionalIterator, class charT, class traits>
-    bool
-    regex_match(BidirectionalIterator first, BidirectionalIterator last,
-                const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class charT, class Allocator, class traits>
-    bool
-    regex_match(const charT* str, match_results<const charT*, Allocator>& m,
-                const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class ST, class SA, class Allocator, class charT, class traits>
-    bool
-    regex_match(const basic_string<charT, ST, SA>& s,
-                match_results<typename basic_string<charT, ST, SA>::const_iterator, Allocator>& m,
-                const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class ST, class SA, class Allocator, class charT, class traits>
-    bool
-    regex_match(const basic_string<charT, ST, SA>&& s,
-                match_results<typename basic_string<charT, ST, SA>::const_iterator, Allocator>& m,
-                const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default) = delete; // C++14
-
-template <class charT, class traits>
-    bool
-    regex_match(const charT* str, const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class ST, class SA, class charT, class traits>
-    bool
-    regex_match(const basic_string<charT, ST, SA>& s,
-                const basic_regex<charT, traits>& e,
-                regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class BidirectionalIterator, class Allocator, class charT, class traits>
-    bool
-    regex_search(BidirectionalIterator first, BidirectionalIterator last,
-                 match_results<BidirectionalIterator, Allocator>& m,
-                 const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class BidirectionalIterator, class charT, class traits>
-    bool
-    regex_search(BidirectionalIterator first, BidirectionalIterator last,
-                 const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class charT, class Allocator, class traits>
-    bool
-    regex_search(const charT* str, match_results<const charT*, Allocator>& m,
-                 const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class charT, class traits>
-    bool
-    regex_search(const charT* str, const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class ST, class SA, class charT, class traits>
-    bool
-    regex_search(const basic_string<charT, ST, SA>& s,
-                 const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class ST, class SA, class Allocator, class charT, class traits>
-    bool
-    regex_search(const basic_string<charT, ST, SA>& s,
-                 match_results<typename basic_string<charT, ST, SA>::const_iterator, Allocator>& m,
-                 const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class ST, class SA, class Allocator, class charT, class traits>
-    bool
-    regex_search(const basic_string<charT, ST, SA>&& s,
-                 match_results<typename basic_string<charT, ST, SA>::const_iterator, Allocator>& m,
-                 const basic_regex<charT, traits>& e,
-                 regex_constants::match_flag_type flags = regex_constants::match_default) = delete; // C++14
-
-template <class OutputIterator, class BidirectionalIterator,
-          class traits, class charT, class ST, class SA>
-    OutputIterator
-    regex_replace(OutputIterator out,
-                  BidirectionalIterator first, BidirectionalIterator last,
-                  const basic_regex<charT, traits>& e,
-                  const basic_string<charT, ST, SA>& fmt,
-                  regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class OutputIterator, class BidirectionalIterator,
-          class traits, class charT>
-    OutputIterator
-    regex_replace(OutputIterator out,
-                  BidirectionalIterator first, BidirectionalIterator last,
-                  const basic_regex<charT, traits>& e, const charT* fmt,
-                  regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class traits, class charT, class ST, class SA, class FST, class FSA>
-    basic_string<charT, ST, SA>
-    regex_replace(const basic_string<charT, ST, SA>& s,
-                  const basic_regex<charT, traits>& e,
-                  const basic_string<charT, FST, FSA>& fmt,
-                  regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class traits, class charT, class ST, class SA>
-    basic_string<charT, ST, SA>
-    regex_replace(const basic_string<charT, ST, SA>& s,
-                  const basic_regex<charT, traits>& e, const charT* fmt,
-                  regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class traits, class charT, class ST, class SA>
-    basic_string<charT>
-    regex_replace(const charT* s,
-                  const basic_regex<charT, traits>& e,
-                  const basic_string<charT, ST, SA>& fmt,
-                  regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class traits, class charT>
-    basic_string<charT>
-    regex_replace(const charT* s,
-                  const basic_regex<charT, traits>& e,
-                  const charT* fmt,
-                  regex_constants::match_flag_type flags = regex_constants::match_default);
-
-template <class BidirectionalIterator,
-          class charT = typename iterator_traits< BidirectionalIterator>::value_type,
-          class traits = regex_traits<charT>>
-class regex_iterator
-{
-public:
-    typedef basic_regex<charT, traits>           regex_type;
-    typedef match_results<BidirectionalIterator> value_type;
-    typedef ptrdiff_t                            difference_type;
-    typedef const value_type*                    pointer;
-    typedef const value_type&                    reference;
-    typedef forward_iterator_tag                 iterator_category;
-
-    regex_iterator();
-    regex_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                   const regex_type& re,
-                   regex_constants::match_flag_type m = regex_constants::match_default);
-    regex_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                   const regex_type&& re,
-                   regex_constants::match_flag_type m
-                                     = regex_constants::match_default) = delete; // C++14
-    regex_iterator(const regex_iterator&);
-    regex_iterator& operator=(const regex_iterator&);
-
-    bool operator==(const regex_iterator&) const;
-    bool operator!=(const regex_iterator&) const;
-
-    const value_type& operator*() const;
-    const value_type* operator->() const;
-
-    regex_iterator& operator++();
-    regex_iterator operator++(int);
-};
-
-typedef regex_iterator<const char*>             cregex_iterator;
-typedef regex_iterator<const wchar_t*>          wcregex_iterator;
-typedef regex_iterator<string::const_iterator>  sregex_iterator;
-typedef regex_iterator<wstring::const_iterator> wsregex_iterator;
-
-template <class BidirectionalIterator,
-          class charT = typename iterator_traits<BidirectionalIterator>::value_type,
-          class traits = regex_traits<charT>>
-class regex_token_iterator
-{
-public:
-    typedef basic_regex<charT, traits>       regex_type;
-    typedef sub_match<BidirectionalIterator> value_type;
-    typedef ptrdiff_t                        difference_type;
-    typedef const value_type*                pointer;
-    typedef const value_type&                reference;
-    typedef forward_iterator_tag             iterator_category;
-
-    regex_token_iterator();
-    regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                         const regex_type& re, int submatch = 0,
-                         regex_constants::match_flag_type m = regex_constants::match_default);
-    regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                         const regex_type&& re, int submatch = 0,
-                         regex_constants::match_flag_type m = regex_constants::match_default) = delete; // C++14
-    regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                         const regex_type& re, const vector<int>& submatches,
-                         regex_constants::match_flag_type m = regex_constants::match_default);
-    regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                         const regex_type&& re, const vector<int>& submatches,
-                         regex_constants::match_flag_type m = regex_constants::match_default) = delete; // C++14
-    regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                         const regex_type& re, initializer_list<int> submatches,
-                         regex_constants::match_flag_type m = regex_constants::match_default);
-    regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                         const regex_type&& re, initializer_list<int> submatches,
-                         regex_constants::match_flag_type m = regex_constants::match_default) = delete; // C++14
-    template <size_t N>
-        regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                             const regex_type& re, const int (&submatches)[N],
-                             regex_constants::match_flag_type m = regex_constants::match_default);
-    template <size_t N>
-        regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
-                             const regex_type&& re, const int (&submatches)[N],
-                             regex_constants::match_flag_type m = regex_constants::match_default) = delete; // C++14
-    regex_token_iterator(const regex_token_iterator&);
-    regex_token_iterator& operator=(const regex_token_iterator&);
-
-    bool operator==(const regex_token_iterator&) const;
-    bool operator!=(const regex_token_iterator&) const;
-
-    const value_type& operator*() const;
-    const value_type* operator->() const;
-
-    regex_token_iterator& operator++();
-    regex_token_iterator operator++(int);
-};
-
-typedef regex_token_iterator<const char*>             cregex_token_iterator;
-typedef regex_token_iterator<const wchar_t*>          wcregex_token_iterator;
-typedef regex_token_iterator<string::const_iterator>  sregex_token_iterator;
-typedef regex_token_iterator<wstring::const_iterator> wsregex_token_iterator;
-
-} // std
-*/
+// Synopsis avaiable at http://wg21.link/re.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/scoped_allocator b/libcxx/include/scoped_allocator
--- a/libcxx/include/scoped_allocator
+++ b/libcxx/include/scoped_allocator
@@ -10,100 +10,7 @@
 #ifndef _LIBCPP_SCOPED_ALLOCATOR
 #define _LIBCPP_SCOPED_ALLOCATOR
 
-/*
-    scoped_allocator synopsis
-
-namespace std
-{
-
-template <class OuterAlloc, class... InnerAllocs>
-class scoped_allocator_adaptor : public OuterAlloc
-{
-    typedef allocator_traits<OuterAlloc> OuterTraits; // exposition only
-    scoped_allocator_adaptor<InnerAllocs...> inner;   // exposition only
-public:
-
-    typedef OuterAlloc outer_allocator_type;
-    typedef see below inner_allocator_type;
-
-    typedef typename OuterTraits::value_type value_type;
-    typedef typename OuterTraits::size_type size_type;
-    typedef typename OuterTraits::difference_type difference_type;
-    typedef typename OuterTraits::pointer pointer;
-    typedef typename OuterTraits::const_pointer const_pointer;
-    typedef typename OuterTraits::void_pointer void_pointer;
-    typedef typename OuterTraits::const_void_pointer const_void_pointer;
-
-    typedef see below propagate_on_container_copy_assignment;
-    typedef see below propagate_on_container_move_assignment;
-    typedef see below propagate_on_container_swap;
-    typedef see below is_always_equal;
-
-    template <class Tp>
-        struct rebind
-        {
-            typedef scoped_allocator_adaptor<
-                OuterTraits::template rebind_alloc<Tp>, InnerAllocs...> other;
-        };
-
-    scoped_allocator_adaptor();
-    template <class OuterA2>
-        scoped_allocator_adaptor(OuterA2&& outerAlloc,
-                                 const InnerAllocs&... innerAllocs) noexcept;
-    scoped_allocator_adaptor(const scoped_allocator_adaptor& other) noexcept;
-    scoped_allocator_adaptor(scoped_allocator_adaptor&& other) noexcept;
-    template <class OuterA2>
-        scoped_allocator_adaptor(const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& other) noexcept;
-    template <class OuterA2>
-        scoped_allocator_adaptor(const scoped_allocator_adaptor<OuterA2, InnerAllocs...>&& other) noexcept;
-
-    scoped_allocator_adaptor& operator=(const scoped_allocator_adaptor&) = default;
-    scoped_allocator_adaptor& operator=(scoped_allocator_adaptor&&) = default;
-    ~scoped_allocator_adaptor();
-
-    inner_allocator_type& inner_allocator() noexcept;
-    const inner_allocator_type& inner_allocator() const noexcept;
-
-    outer_allocator_type& outer_allocator() noexcept;
-    const outer_allocator_type& outer_allocator() const noexcept;
-
-    pointer allocate(size_type n);                           // [[nodiscard]] in C++20
-    pointer allocate(size_type n, const_void_pointer hint);  // [[nodiscard]] in C++20
-    void deallocate(pointer p, size_type n) noexcept;
-
-    size_type max_size() const;
-    template <class T, class... Args> void construct(T* p, Args&& args);
-    template <class T1, class T2, class... Args1, class... Args2>
-        void construct(pair<T1, T2>* p, piecewise_construct t, tuple<Args1...> x,
-                       tuple<Args2...> y);
-    template <class T1, class T2>
-        void construct(pair<T1, T2>* p);
-    template <class T1, class T2, class U, class V>
-        void construct(pair<T1, T2>* p, U&& x, V&& y);
-    template <class T1, class T2, class U, class V>
-        void construct(pair<T1, T2>* p, const pair<U, V>& x);
-    template <class T1, class T2, class U, class V>
-        void construct(pair<T1, T2>* p, pair<U, V>&& x);
-    template <class T> void destroy(T* p);
-
-    template <class T> void destroy(T* p) noexcept;
-
-    scoped_allocator_adaptor select_on_container_copy_construction() const noexcept;
-};
-
-template <class OuterA1, class OuterA2, class... InnerAllocs>
-    bool
-    operator==(const scoped_allocator_adaptor<OuterA1, InnerAllocs...>& a,
-               const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& b) noexcept;
-
-template <class OuterA1, class OuterA2, class... InnerAllocs>
-    bool
-    operator!=(const scoped_allocator_adaptor<OuterA1, InnerAllocs...>& a,
-               const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& b) noexcept;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/allocator.adaptor.syn.
 
 #include <__config>
 #include <__utility/forward.h>
diff --git a/libcxx/include/semaphore b/libcxx/include/semaphore
--- a/libcxx/include/semaphore
+++ b/libcxx/include/semaphore
@@ -9,41 +9,7 @@
 
 #ifndef _LIBCPP_SEMAPHORE
 #define _LIBCPP_SEMAPHORE
-
-/*
-    semaphore synopsis
-
-namespace std {
-
-template<ptrdiff_t least_max_value = implementation-defined>
-class counting_semaphore
-{
-public:
-static constexpr ptrdiff_t max() noexcept;
-
-constexpr explicit counting_semaphore(ptrdiff_t desired);
-~counting_semaphore();
-
-counting_semaphore(const counting_semaphore&) = delete;
-counting_semaphore& operator=(const counting_semaphore&) = delete;
-
-void release(ptrdiff_t update = 1);
-void acquire();
-bool try_acquire() noexcept;
-template<class Rep, class Period>
-    bool try_acquire_for(const chrono::duration<Rep, Period>& rel_time);
-template<class Clock, class Duration>
-    bool try_acquire_until(const chrono::time_point<Clock, Duration>& abs_time);
-
-private:
-ptrdiff_t counter; // exposition only
-};
-
-using binary_semaphore = counting_semaphore<1>;
-
-}
-
-*/
+// Synopsis avaiable at http://wg21.link/semaphore.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/set b/libcxx/include/set
--- a/libcxx/include/set
+++ b/libcxx/include/set
@@ -10,428 +10,7 @@
 #ifndef _LIBCPP_SET
 #define _LIBCPP_SET
 
-/*
-
-    set synopsis
-
-namespace std
-{
-
-template <class Key, class Compare = less<Key>,
-          class Allocator = allocator<Key>>
-class set
-{
-public:
-    // types:
-    typedef Key                                      key_type;
-    typedef key_type                                 value_type;
-    typedef Compare                                  key_compare;
-    typedef key_compare                              value_compare;
-    typedef Allocator                                allocator_type;
-    typedef typename allocator_type::reference       reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-    typedef typename allocator_type::pointer         pointer;
-    typedef typename allocator_type::const_pointer   const_pointer;
-
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-    typedef unspecified                              node_type;               // C++17
-    typedef INSERT_RETURN_TYPE<iterator, node_type>  insert_return_type;      // C++17
-
-    // construct/copy/destroy:
-    set()
-        noexcept(
-            is_nothrow_default_constructible<allocator_type>::value &&
-            is_nothrow_default_constructible<key_compare>::value &&
-            is_nothrow_copy_constructible<key_compare>::value);
-    explicit set(const value_compare& comp);
-    set(const value_compare& comp, const allocator_type& a);
-    template <class InputIterator>
-        set(InputIterator first, InputIterator last,
-            const value_compare& comp = value_compare());
-    template <class InputIterator>
-        set(InputIterator first, InputIterator last, const value_compare& comp,
-            const allocator_type& a);
-    set(const set& s);
-    set(set&& s)
-        noexcept(
-            is_nothrow_move_constructible<allocator_type>::value &&
-            is_nothrow_move_constructible<key_compare>::value);
-    explicit set(const allocator_type& a);
-    set(const set& s, const allocator_type& a);
-    set(set&& s, const allocator_type& a);
-    set(initializer_list<value_type> il, const value_compare& comp = value_compare());
-    set(initializer_list<value_type> il, const value_compare& comp,
-        const allocator_type& a);
-    template <class InputIterator>
-        set(InputIterator first, InputIterator last, const allocator_type& a)
-            : set(first, last, Compare(), a) {}  // C++14
-    set(initializer_list<value_type> il, const allocator_type& a)
-        : set(il, Compare(), a) {}  // C++14
-    ~set();
-
-    set& operator=(const set& s);
-    set& operator=(set&& s)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<key_compare>::value);
-    set& operator=(initializer_list<value_type> il);
-
-    // iterators:
-          iterator begin() noexcept;
-    const_iterator begin() const noexcept;
-          iterator end() noexcept;
-    const_iterator end()   const noexcept;
-
-          reverse_iterator rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-          reverse_iterator rend() noexcept;
-    const_reverse_iterator rend()   const noexcept;
-
-    const_iterator         cbegin()  const noexcept;
-    const_iterator         cend()    const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend()   const noexcept;
-
-    // capacity:
-    bool      empty()    const noexcept;
-    size_type size()     const noexcept;
-    size_type max_size() const noexcept;
-
-    // modifiers:
-    template <class... Args>
-        pair<iterator, bool> emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    pair<iterator,bool> insert(const value_type& v);
-    pair<iterator,bool> insert(value_type&& v);
-    iterator insert(const_iterator position, const value_type& v);
-    iterator insert(const_iterator position, value_type&& v);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type> il);
-
-    node_type extract(const_iterator position);                                       // C++17
-    node_type extract(const key_type& x);                                             // C++17
-    insert_return_type insert(node_type&& nh);                                        // C++17
-    iterator insert(const_iterator hint, node_type&& nh);                             // C++17
-
-    iterator  erase(const_iterator position);
-    iterator  erase(iterator position);  // C++14
-    size_type erase(const key_type& k);
-    iterator  erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class C2>
-      void merge(set<Key, C2, Allocator>& source);         // C++17
-    template<class C2>
-      void merge(set<Key, C2, Allocator>&& source);        // C++17
-    template<class C2>
-      void merge(multiset<Key, C2, Allocator>& source);    // C++17
-    template<class C2>
-      void merge(multiset<Key, C2, Allocator>&& source);   // C++17
-
-    void swap(set& s)
-        noexcept(
-            __is_nothrow_swappable<key_compare>::value &&
-            (!allocator_type::propagate_on_container_swap::value ||
-             __is_nothrow_swappable<allocator_type>::value));
-
-    // observers:
-    allocator_type get_allocator() const noexcept;
-    key_compare    key_comp()      const;
-    value_compare  value_comp()    const;
-
-    // set operations:
-          iterator find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++14
-
-    template<typename K>
-        size_type count(const K& x) const;        // C++14
-    size_type      count(const key_type& k) const;
-
-    bool           contains(const key_type& x) const;  // C++20
-    template<class K> bool contains(const K& x) const; // C++20
-
-          iterator lower_bound(const key_type& k);
-    const_iterator lower_bound(const key_type& k) const;
-    template<typename K>
-        iterator lower_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator lower_bound(const K& x) const;  // C++14
-
-          iterator upper_bound(const key_type& k);
-    const_iterator upper_bound(const key_type& k) const;
-    template<typename K>
-        iterator upper_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator upper_bound(const K& x) const;  // C++14
-    pair<iterator,iterator>             equal_range(const key_type& k);
-    pair<const_iterator,const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator,iterator>             equal_range(const K& x);        // C++14
-    template<typename K>
-        pair<const_iterator,const_iterator> equal_range(const K& x) const;  // C++14
-};
-
-template <class Key, class Compare, class Allocator>
-bool
-operator==(const set<Key, Compare, Allocator>& x,
-           const set<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator< (const set<Key, Compare, Allocator>& x,
-           const set<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator!=(const set<Key, Compare, Allocator>& x,
-           const set<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator> (const set<Key, Compare, Allocator>& x,
-           const set<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator>=(const set<Key, Compare, Allocator>& x,
-           const set<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator<=(const set<Key, Compare, Allocator>& x,
-           const set<Key, Compare, Allocator>& y);
-
-// specialized algorithms:
-template <class Key, class Compare, class Allocator>
-void
-swap(set<Key, Compare, Allocator>& x, set<Key, Compare, Allocator>& y)
-    noexcept(noexcept(x.swap(y)));
-
-template <class Key, class Compare, class Allocator, class Predicate>
-typename set<Key, Compare, Allocator>::size_type
-erase_if(set<Key, Compare, Allocator>& c, Predicate pred);  // C++20
-
-template <class Key, class Compare = less<Key>,
-          class Allocator = allocator<Key>>
-class multiset
-{
-public:
-    // types:
-    typedef Key                                      key_type;
-    typedef key_type                                 value_type;
-    typedef Compare                                  key_compare;
-    typedef key_compare                              value_compare;
-    typedef Allocator                                allocator_type;
-    typedef typename allocator_type::reference       reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-    typedef typename allocator_type::pointer         pointer;
-    typedef typename allocator_type::const_pointer   const_pointer;
-
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-    typedef unspecified                              node_type;               // C++17
-
-    // construct/copy/destroy:
-    multiset()
-        noexcept(
-            is_nothrow_default_constructible<allocator_type>::value &&
-            is_nothrow_default_constructible<key_compare>::value &&
-            is_nothrow_copy_constructible<key_compare>::value);
-    explicit multiset(const value_compare& comp);
-    multiset(const value_compare& comp, const allocator_type& a);
-    template <class InputIterator>
-        multiset(InputIterator first, InputIterator last,
-                 const value_compare& comp = value_compare());
-    template <class InputIterator>
-        multiset(InputIterator first, InputIterator last,
-                 const value_compare& comp, const allocator_type& a);
-    multiset(const multiset& s);
-    multiset(multiset&& s)
-        noexcept(
-            is_nothrow_move_constructible<allocator_type>::value &&
-            is_nothrow_move_constructible<key_compare>::value);
-    explicit multiset(const allocator_type& a);
-    multiset(const multiset& s, const allocator_type& a);
-    multiset(multiset&& s, const allocator_type& a);
-    multiset(initializer_list<value_type> il, const value_compare& comp = value_compare());
-    multiset(initializer_list<value_type> il, const value_compare& comp,
-             const allocator_type& a);
-    template <class InputIterator>
-        multiset(InputIterator first, InputIterator last, const allocator_type& a)
-            : set(first, last, Compare(), a) {}  // C++14
-    multiset(initializer_list<value_type> il, const allocator_type& a)
-        : set(il, Compare(), a) {}  // C++14
-    ~multiset();
-
-    multiset& operator=(const multiset& s);
-    multiset& operator=(multiset&& s)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<key_compare>::value);
-    multiset& operator=(initializer_list<value_type> il);
-
-    // iterators:
-          iterator begin() noexcept;
-    const_iterator begin() const noexcept;
-          iterator end() noexcept;
-    const_iterator end()   const noexcept;
-
-          reverse_iterator rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-          reverse_iterator rend() noexcept;
-    const_reverse_iterator rend()   const noexcept;
-
-    const_iterator         cbegin()  const noexcept;
-    const_iterator         cend()    const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend()   const noexcept;
-
-    // capacity:
-    bool      empty()    const noexcept;
-    size_type size()     const noexcept;
-    size_type max_size() const noexcept;
-
-    // modifiers:
-    template <class... Args>
-        iterator emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    iterator insert(const value_type& v);
-    iterator insert(value_type&& v);
-    iterator insert(const_iterator position, const value_type& v);
-    iterator insert(const_iterator position, value_type&& v);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type> il);
-
-    node_type extract(const_iterator position);                                       // C++17
-    node_type extract(const key_type& x);                                             // C++17
-    iterator insert(node_type&& nh);                                                  // C++17
-    iterator insert(const_iterator hint, node_type&& nh);                             // C++17
-
-    iterator  erase(const_iterator position);
-    iterator  erase(iterator position);  // C++14
-    size_type erase(const key_type& k);
-    iterator  erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class C2>
-      void merge(multiset<Key, C2, Allocator>& source);    // C++17
-    template<class C2>
-      void merge(multiset<Key, C2, Allocator>&& source);   // C++17
-    template<class C2>
-      void merge(set<Key, C2, Allocator>& source);         // C++17
-    template<class C2>
-      void merge(set<Key, C2, Allocator>&& source);        // C++17
-
-    void swap(multiset& s)
-        noexcept(
-            __is_nothrow_swappable<key_compare>::value &&
-            (!allocator_type::propagate_on_container_swap::value ||
-             __is_nothrow_swappable<allocator_type>::value));
-
-    // observers:
-    allocator_type get_allocator() const noexcept;
-    key_compare    key_comp()      const;
-    value_compare  value_comp()    const;
-
-    // set operations:
-          iterator find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++14
-
-    template<typename K>
-        size_type count(const K& x) const;      // C++14
-    size_type      count(const key_type& k) const;
-
-    bool           contains(const key_type& x) const;  // C++20
-    template<class K> bool contains(const K& x) const; // C++20
-
-          iterator lower_bound(const key_type& k);
-    const_iterator lower_bound(const key_type& k) const;
-    template<typename K>
-        iterator lower_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator lower_bound(const K& x) const;  // C++14
-
-          iterator upper_bound(const key_type& k);
-    const_iterator upper_bound(const key_type& k) const;
-    template<typename K>
-        iterator upper_bound(const K& x);              // C++14
-    template<typename K>
-        const_iterator upper_bound(const K& x) const;  // C++14
-
-    pair<iterator,iterator>             equal_range(const key_type& k);
-    pair<const_iterator,const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator,iterator>             equal_range(const K& x);        // C++14
-    template<typename K>
-        pair<const_iterator,const_iterator> equal_range(const K& x) const;  // C++14
-};
-
-template <class Key, class Compare, class Allocator>
-bool
-operator==(const multiset<Key, Compare, Allocator>& x,
-           const multiset<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator< (const multiset<Key, Compare, Allocator>& x,
-           const multiset<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator!=(const multiset<Key, Compare, Allocator>& x,
-           const multiset<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator> (const multiset<Key, Compare, Allocator>& x,
-           const multiset<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator>=(const multiset<Key, Compare, Allocator>& x,
-           const multiset<Key, Compare, Allocator>& y);
-
-template <class Key, class Compare, class Allocator>
-bool
-operator<=(const multiset<Key, Compare, Allocator>& x,
-           const multiset<Key, Compare, Allocator>& y);
-
-// specialized algorithms:
-template <class Key, class Compare, class Allocator>
-void
-swap(multiset<Key, Compare, Allocator>& x, multiset<Key, Compare, Allocator>& y)
-    noexcept(noexcept(x.swap(y)));
-
-template <class Key, class Compare, class Allocator, class Predicate>
-typename multiset<Key, Compare, Allocator>::size_type
-erase_if(multiset<Key, Compare, Allocator>& c, Predicate pred);  // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/associative.set.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/shared_mutex b/libcxx/include/shared_mutex
--- a/libcxx/include/shared_mutex
+++ b/libcxx/include/shared_mutex
@@ -10,117 +10,7 @@
 #ifndef _LIBCPP_SHARED_MUTEX
 #define _LIBCPP_SHARED_MUTEX
 
-/*
-    shared_mutex synopsis
-
-// C++1y
-
-namespace std
-{
-
-class shared_mutex      // C++17
-{
-public:
-    shared_mutex();
-    ~shared_mutex();
-
-    shared_mutex(const shared_mutex&) = delete;
-    shared_mutex& operator=(const shared_mutex&) = delete;
-
-    // Exclusive ownership
-    void lock(); // blocking
-    bool try_lock();
-    void unlock();
-
-    // Shared ownership
-    void lock_shared(); // blocking
-    bool try_lock_shared();
-    void unlock_shared();
-
-    typedef implementation-defined native_handle_type; // See 30.2.3
-    native_handle_type native_handle(); // See 30.2.3
-};
-
-class shared_timed_mutex
-{
-public:
-    shared_timed_mutex();
-    ~shared_timed_mutex();
-
-    shared_timed_mutex(const shared_timed_mutex&) = delete;
-    shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
-
-    // Exclusive ownership
-    void lock(); // blocking
-    bool try_lock();
-    template <class Rep, class Period>
-        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
-    template <class Clock, class Duration>
-        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
-    void unlock();
-
-    // Shared ownership
-    void lock_shared(); // blocking
-    bool try_lock_shared();
-    template <class Rep, class Period>
-        bool
-        try_lock_shared_for(const chrono::duration<Rep, Period>& rel_time);
-    template <class Clock, class Duration>
-        bool
-        try_lock_shared_until(const chrono::time_point<Clock, Duration>& abs_time);
-    void unlock_shared();
-};
-
-template <class Mutex>
-class shared_lock
-{
-public:
-    typedef Mutex mutex_type;
-
-    // Shared locking
-    shared_lock() noexcept;
-    explicit shared_lock(mutex_type& m); // blocking
-    shared_lock(mutex_type& m, defer_lock_t) noexcept;
-    shared_lock(mutex_type& m, try_to_lock_t);
-    shared_lock(mutex_type& m, adopt_lock_t);
-    template <class Clock, class Duration>
-        shared_lock(mutex_type& m,
-                    const chrono::time_point<Clock, Duration>& abs_time);
-    template <class Rep, class Period>
-        shared_lock(mutex_type& m,
-                    const chrono::duration<Rep, Period>& rel_time);
-    ~shared_lock();
-
-    shared_lock(shared_lock const&) = delete;
-    shared_lock& operator=(shared_lock const&) = delete;
-
-    shared_lock(shared_lock&& u) noexcept;
-    shared_lock& operator=(shared_lock&& u) noexcept;
-
-    void lock(); // blocking
-    bool try_lock();
-    template <class Rep, class Period>
-        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
-    template <class Clock, class Duration>
-        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
-    void unlock();
-
-    // Setters
-    void swap(shared_lock& u) noexcept;
-    mutex_type* release() noexcept;
-
-    // Getters
-    bool owns_lock() const noexcept;
-    explicit operator bool () const noexcept;
-    mutex_type* mutex() const noexcept;
-};
-
-template <class Mutex>
-    void swap(shared_lock<Mutex>& x, shared_lock<Mutex>& y) noexcept;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/shared.mutex.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/span b/libcxx/include/span
--- a/libcxx/include/span
+++ b/libcxx/include/span
@@ -10,122 +10,7 @@
 #ifndef _LIBCPP_SPAN
 #define _LIBCPP_SPAN
 
-/*
-    span synopsis
-
-namespace std {
-
-// constants
-inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max();
-
-// [views.span], class template span
-template <class ElementType, size_t Extent = dynamic_extent>
-    class span;
-
-template<class ElementType, size_t Extent>
-  inline constexpr bool ranges::enable_view<span<ElementType, Extent>> = true;
-
-template<class ElementType, size_t Extent>
-    inline constexpr bool ranges::enable_borrowed_range<span<ElementType, Extent>> = true;
-
-// [span.objectrep], views of object representation
-template <class ElementType, size_t Extent>
-    span<const byte, ((Extent == dynamic_extent) ? dynamic_extent :
-        (sizeof(ElementType) * Extent))> as_bytes(span<ElementType, Extent> s) noexcept;
-
-template <class ElementType, size_t Extent>
-    span<      byte, ((Extent == dynamic_extent) ? dynamic_extent :
-        (sizeof(ElementType) * Extent))> as_writable_bytes(span<ElementType, Extent> s) noexcept;
-
-
-template <class ElementType, size_t Extent = dynamic_extent>
-class span {
-public:
-    // constants and types
-    using element_type = ElementType;
-    using value_type = remove_cv_t<ElementType>;
-    using size_type = size_t;
-    using difference_type = ptrdiff_t;
-    using pointer = element_type*;
-    using const_pointer = const element_type*;
-    using reference = element_type&;
-    using const_reference = const element_type&;
-    using iterator = implementation-defined;
-    using reverse_iterator = std::reverse_iterator<iterator>;
-    static constexpr size_type extent = Extent;
-
-    // [span.cons], span constructors, copy, assignment, and destructor
-    constexpr span() noexcept;
-    constexpr explicit(Extent != dynamic_extent) span(pointer ptr, size_type count);
-    constexpr explicit(Extent != dynamic_extent) span(pointer firstElem, pointer lastElem);
-    template <size_t N>
-        constexpr span(element_type (&arr)[N]) noexcept;
-    template <size_t N>
-        constexpr span(array<value_type, N>& arr) noexcept;
-    template <size_t N>
-        constexpr span(const array<value_type, N>& arr) noexcept;
-    template <class Container>
-        constexpr explicit(Extent != dynamic_extent) span(Container& cont);
-    template <class Container>
-        constexpr explicit(Extent != dynamic_extent) span(const Container& cont);
-    constexpr span(const span& other) noexcept = default;
-    template <class OtherElementType, size_t OtherExtent>
-        constexpr explicit(Extent != dynamic_extent) span(const span<OtherElementType, OtherExtent>& s) noexcept;
-    ~span() noexcept = default;
-    constexpr span& operator=(const span& other) noexcept = default;
-
-    // [span.sub], span subviews
-    template <size_t Count>
-        constexpr span<element_type, Count> first() const;
-    template <size_t Count>
-        constexpr span<element_type, Count> last() const;
-    template <size_t Offset, size_t Count = dynamic_extent>
-        constexpr span<element_type, see below> subspan() const;
-
-    constexpr span<element_type, dynamic_extent> first(size_type count) const;
-    constexpr span<element_type, dynamic_extent> last(size_type count) const;
-    constexpr span<element_type, dynamic_extent> subspan(size_type offset, size_type count = dynamic_extent) const;
-
-    // [span.obs], span observers
-    constexpr size_type size() const noexcept;
-    constexpr size_type size_bytes() const noexcept;
-    constexpr bool empty() const noexcept;
-
-    // [span.elem], span element access
-    constexpr reference operator[](size_type idx) const;
-    constexpr reference front() const;
-    constexpr reference back() const;
-    constexpr pointer data() const noexcept;
-
-    // [span.iterators], span iterator support
-    constexpr iterator begin() const noexcept;
-    constexpr iterator end() const noexcept;
-    constexpr reverse_iterator rbegin() const noexcept;
-    constexpr reverse_iterator rend() const noexcept;
-
-private:
-    pointer data_;    // exposition only
-    size_type size_;  // exposition only
-};
-
-template<class T, size_t N>
-    span(T (&)[N]) -> span<T, N>;
-
-template<class T, size_t N>
-    span(array<T, N>&) -> span<T, N>;
-
-template<class T, size_t N>
-    span(const array<T, N>&) -> span<const T, N>;
-
-template<class Container>
-    span(Container&) -> span<typename Container::value_type>;
-
-template<class Container>
-    span(const Container&) -> span<const typename Container::value_type>;
-
-} // namespace std
-
-*/
+// Synopsis avaiable at http://wg21.link/span.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/sstream b/libcxx/include/sstream
--- a/libcxx/include/sstream
+++ b/libcxx/include/sstream
@@ -10,175 +10,7 @@
 #ifndef _LIBCPP_SSTREAM
 #define _LIBCPP_SSTREAM
 
-/*
-    sstream synopsis
-
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-class basic_stringbuf
-    : public basic_streambuf<charT, traits>
-{
-public:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-    typedef Allocator                      allocator_type;
-
-    // 27.8.1.1 [stringbuf.cons], constructors:
-    explicit basic_stringbuf(ios_base::openmode which = ios_base::in | ios_base::out); // before C++20
-    basic_stringbuf() : basic_stringbuf(ios_base::in | ios_base::out) {}               // C++20
-    explicit basic_stringbuf(ios_base::openmode which);                                // C++20
-    explicit basic_stringbuf(const basic_string<char_type, traits_type, allocator_type>& str,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    basic_stringbuf(basic_stringbuf&& rhs);
-
-    // 27.8.1.2 Assign and swap:
-    basic_stringbuf& operator=(basic_stringbuf&& rhs);
-    void swap(basic_stringbuf& rhs);
-
-    // 27.8.1.3 Get and set:
-    basic_string<char_type, traits_type, allocator_type> str() const;
-    void str(const basic_string<char_type, traits_type, allocator_type>& s);
-
-protected:
-    // 27.8.1.4 Overridden virtual functions:
-    virtual int_type underflow();
-    virtual int_type pbackfail(int_type c = traits_type::eof());
-    virtual int_type overflow (int_type c = traits_type::eof());
-    virtual basic_streambuf<char_type, traits_type>* setbuf(char_type*, streamsize);
-    virtual pos_type seekoff(off_type off, ios_base::seekdir way,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual pos_type seekpos(pos_type sp,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-};
-
-template <class charT, class traits, class Allocator>
-  void swap(basic_stringbuf<charT, traits, Allocator>& x,
-            basic_stringbuf<charT, traits, Allocator>& y);
-
-typedef basic_stringbuf<char>    stringbuf;
-typedef basic_stringbuf<wchar_t> wstringbuf;
-
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-class basic_istringstream
-    : public basic_istream<charT, traits>
-{
-public:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-    typedef Allocator                      allocator_type;
-
-    // 27.8.2.1 Constructors:
-    explicit basic_istringstream(ios_base::openmode which = ios_base::in); // before C++20
-    basic_istringstream() : basic_istringstream(ios_base::in) {}           // C++20
-    explicit basic_istringstream(ios_base::openmode which);                // C++20
-
-    explicit basic_istringstream(const basic_string<char_type, traits_type,allocator_type>& str,
-                                 ios_base::openmode which = ios_base::in);
-    basic_istringstream(basic_istringstream&& rhs);
-
-    // 27.8.2.2 Assign and swap:
-    basic_istringstream& operator=(basic_istringstream&& rhs);
-    void swap(basic_istringstream& rhs);
-
-    // 27.8.2.3 Members:
-    basic_stringbuf<char_type, traits_type, allocator_type>* rdbuf() const;
-    basic_string<char_type, traits_type, allocator_type> str() const;
-    void str(const basic_string<char_type, traits_type, allocator_type>& s);
-};
-
-template <class charT, class traits, class Allocator>
-  void swap(basic_istringstream<charT, traits, Allocator>& x,
-            basic_istringstream<charT, traits, Allocator>& y);
-
-typedef basic_istringstream<char>    istringstream;
-typedef basic_istringstream<wchar_t> wistringstream;
-
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-class basic_ostringstream
-    : public basic_ostream<charT, traits>
-{
-public:
-    // types:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-    typedef Allocator                      allocator_type;
-
-    // 27.8.3.1 Constructors/destructor:
-    explicit basic_ostringstream(ios_base::openmode which = ios_base::out); // before C++20
-    basic_ostringstream() : basic_ostringstream(ios_base::out) {}           // C++20
-    explicit basic_ostringstream(ios_base::openmode which);                 // C++20
-
-    explicit basic_ostringstream(const basic_string<char_type, traits_type, allocator_type>& str,
-                                 ios_base::openmode which = ios_base::out);
-    basic_ostringstream(basic_ostringstream&& rhs);
-
-    // 27.8.3.2 Assign/swap:
-    basic_ostringstream& operator=(basic_ostringstream&& rhs);
-    void swap(basic_ostringstream& rhs);
-
-    // 27.8.3.3 Members:
-    basic_stringbuf<char_type, traits_type, allocator_type>* rdbuf() const;
-    basic_string<char_type, traits_type, allocator_type> str() const;
-    void str(const basic_string<char_type, traits_type, allocator_type>& s);
-};
-
-template <class charT, class traits, class Allocator>
-  void swap(basic_ostringstream<charT, traits, Allocator>& x,
-            basic_ostringstream<charT, traits, Allocator>& y);
-
-typedef basic_ostringstream<char>    ostringstream;
-typedef basic_ostringstream<wchar_t> wostringstream;
-
-template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-class basic_stringstream
-    : public basic_iostream<charT, traits>
-{
-public:
-    // types:
-    typedef charT                          char_type;
-    typedef traits                         traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-    typedef Allocator                      allocator_type;
-
-    // constructors/destructor
-    explicit basic_stringstream(ios_base::openmode which = ios_base::out | ios_base::in); // before C++20
-    basic_stringstream() : basic_stringstream(ios_base::out | ios_base::in) {}            // C++20
-    explicit basic_stringstream(ios_base::openmode which);                                // C++20
-
-    explicit basic_stringstream(const basic_string<char_type, traits_type, allocator_type>& str,
-                                ios_base::openmode which = ios_base::out|ios_base::in);
-    basic_stringstream(basic_stringstream&& rhs);
-
-    // 27.8.5.1 Assign/swap:
-    basic_stringstream& operator=(basic_stringstream&& rhs);
-    void swap(basic_stringstream& rhs);
-
-    // Members:
-    basic_stringbuf<char_type, traits_type, allocator_type>* rdbuf() const;
-    basic_string<char_type, traits_type, allocator_type> str() const;
-    void str(const basic_string<char_type, traits_type, allocator_type>& str);
-};
-
-template <class charT, class traits, class Allocator>
-  void swap(basic_stringstream<charT, traits, Allocator>& x,
-            basic_stringstream<charT, traits, Allocator>& y);
-
-typedef basic_stringstream<char>    stringstream;
-typedef basic_stringstream<wchar_t> wstringstream;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/sstream.syn.
 
 #include <__config>
 #include <istream>
diff --git a/libcxx/include/stack b/libcxx/include/stack
--- a/libcxx/include/stack
+++ b/libcxx/include/stack
@@ -10,82 +10,7 @@
 #ifndef _LIBCPP_STACK
 #define _LIBCPP_STACK
 
-/*
-    stack synopsis
-
-namespace std
-{
-
-template <class T, class Container = deque<T>>
-class stack
-{
-public:
-    typedef Container                                container_type;
-    typedef typename container_type::value_type      value_type;
-    typedef typename container_type::reference       reference;
-    typedef typename container_type::const_reference const_reference;
-    typedef typename container_type::size_type       size_type;
-
-protected:
-    container_type c;
-
-public:
-    stack() = default;
-    ~stack() = default;
-
-    stack(const stack& q) = default;
-    stack(stack&& q) = default;
-
-    stack& operator=(const stack& q) = default;
-    stack& operator=(stack&& q) = default;
-
-    explicit stack(const container_type& c);
-    explicit stack(container_type&& c);
-    template <class Alloc> explicit stack(const Alloc& a);
-    template <class Alloc> stack(const container_type& c, const Alloc& a);
-    template <class Alloc> stack(container_type&& c, const Alloc& a);
-    template <class Alloc> stack(const stack& c, const Alloc& a);
-    template <class Alloc> stack(stack&& c, const Alloc& a);
-
-    bool empty() const;
-    size_type size() const;
-    reference top();
-    const_reference top() const;
-
-    void push(const value_type& x);
-    void push(value_type&& x);
-    template <class... Args> reference emplace(Args&&... args); // reference in C++17
-    void pop();
-
-    void swap(stack& c) noexcept(is_nothrow_swappable_v<Container>)
-};
-
-template<class Container>
-  stack(Container) -> stack<typename Container::value_type, Container>;  // C++17
-
-template<class Container, class Allocator>
-  stack(Container, Allocator) -> stack<typename Container::value_type, Container>; // C++17
-
-template <class T, class Container>
-  bool operator==(const stack<T, Container>& x, const stack<T, Container>& y);
-template <class T, class Container>
-  bool operator< (const stack<T, Container>& x, const stack<T, Container>& y);
-template <class T, class Container>
-  bool operator!=(const stack<T, Container>& x, const stack<T, Container>& y);
-template <class T, class Container>
-  bool operator> (const stack<T, Container>& x, const stack<T, Container>& y);
-template <class T, class Container>
-  bool operator>=(const stack<T, Container>& x, const stack<T, Container>& y);
-template <class T, class Container>
-  bool operator<=(const stack<T, Container>& x, const stack<T, Container>& y);
-
-template <class T, class Container>
-  void swap(stack<T, Container>& x, stack<T, Container>& y)
-  noexcept(noexcept(x.swap(y)));
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/stack.syn.
 
 #include <__config>
 #include <__utility/forward.h>
diff --git a/libcxx/include/stdexcept b/libcxx/include/stdexcept
--- a/libcxx/include/stdexcept
+++ b/libcxx/include/stdexcept
@@ -10,36 +10,7 @@
 #ifndef _LIBCPP_STDEXCEPT
 #define _LIBCPP_STDEXCEPT
 
-/*
-    stdexcept synopsis
-
-namespace std
-{
-
-class logic_error;
-    class domain_error;
-    class invalid_argument;
-    class length_error;
-    class out_of_range;
-class runtime_error;
-    class range_error;
-    class overflow_error;
-    class underflow_error;
-
-for each class xxx_error:
-
-class xxx_error : public exception // at least indirectly
-{
-public:
-    explicit xxx_error(const string& what_arg);
-    explicit xxx_error(const char*   what_arg);
-
-    virtual const char* what() const noexcept // returns what_arg
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/stdexcept.syn.
 
 #include <__config>
 #include <exception>
diff --git a/libcxx/include/streambuf b/libcxx/include/streambuf
--- a/libcxx/include/streambuf
+++ b/libcxx/include/streambuf
@@ -10,102 +10,7 @@
 #ifndef _LIBCPP_STREAMBUF
 #define _LIBCPP_STREAMBUF
 
-/*
-    streambuf synopsis
-
-namespace std
-{
-
-template <class charT, class traits = char_traits<charT> >
-class basic_streambuf
-{
-public:
-    // types:
-    typedef charT char_type;
-    typedef traits traits_type;
-    typedef typename traits_type::int_type int_type;
-    typedef typename traits_type::pos_type pos_type;
-    typedef typename traits_type::off_type off_type;
-
-    virtual ~basic_streambuf();
-
-    // 27.6.2.2.1 locales:
-    locale pubimbue(const locale& loc);
-    locale getloc() const;
-
-    // 27.6.2.2.2 buffer and positioning:
-    basic_streambuf* pubsetbuf(char_type* s, streamsize n);
-    pos_type pubseekoff(off_type off, ios_base::seekdir way,
-                        ios_base::openmode which = ios_base::in | ios_base::out);
-    pos_type pubseekpos(pos_type sp,
-                        ios_base::openmode which = ios_base::in | ios_base::out);
-    int pubsync();
-
-    // Get and put areas:
-    // 27.6.2.2.3 Get area:
-    streamsize in_avail();
-    int_type snextc();
-    int_type sbumpc();
-    int_type sgetc();
-    streamsize sgetn(char_type* s, streamsize n);
-
-    // 27.6.2.2.4 Putback:
-    int_type sputbackc(char_type c);
-    int_type sungetc();
-
-    // 27.6.2.2.5 Put area:
-    int_type sputc(char_type c);
-    streamsize sputn(const char_type* s, streamsize n);
-
-protected:
-    basic_streambuf();
-    basic_streambuf(const basic_streambuf& rhs);
-    basic_streambuf& operator=(const basic_streambuf& rhs);
-    void swap(basic_streambuf& rhs);
-
-    // 27.6.2.3.2 Get area:
-    char_type* eback() const;
-    char_type* gptr() const;
-    char_type* egptr() const;
-    void gbump(int n);
-    void setg(char_type* gbeg, char_type* gnext, char_type* gend);
-
-    // 27.6.2.3.3 Put area:
-    char_type* pbase() const;
-    char_type* pptr() const;
-    char_type* epptr() const;
-    void pbump(int n);
-    void setp(char_type* pbeg, char_type* pend);
-
-    // 27.6.2.4 virtual functions:
-    // 27.6.2.4.1 Locales:
-    virtual void imbue(const locale& loc);
-
-    // 27.6.2.4.2 Buffer management and positioning:
-    virtual basic_streambuf* setbuf(char_type* s, streamsize n);
-    virtual pos_type seekoff(off_type off, ios_base::seekdir way,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual pos_type seekpos(pos_type sp,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual int sync();
-
-    // 27.6.2.4.3 Get area:
-    virtual streamsize showmanyc();
-    virtual streamsize xsgetn(char_type* s, streamsize n);
-    virtual int_type underflow();
-    virtual int_type uflow();
-
-    // 27.6.2.4.4 Putback:
-    virtual int_type pbackfail(int_type c = traits_type::eof());
-
-    // 27.6.2.4.5 Put area:
-    virtual streamsize xsputn(const char_type* s, streamsize n);
-    virtual int_type overflow (int_type c = traits_type::eof());
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/streambuf.syn.
 
 #include <__config>
 #include <ios>
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -10,508 +10,7 @@
 #ifndef _LIBCPP_STRING
 #define _LIBCPP_STRING
 
-/*
-    string synopsis
-
-namespace std
-{
-
-template <class stateT>
-class fpos
-{
-private:
-    stateT st;
-public:
-    fpos(streamoff = streamoff());
-
-    operator streamoff() const;
-
-    stateT state() const;
-    void state(stateT);
-
-    fpos& operator+=(streamoff);
-    fpos  operator+ (streamoff) const;
-    fpos& operator-=(streamoff);
-    fpos  operator- (streamoff) const;
-};
-
-template <class stateT> streamoff operator-(const fpos<stateT>& x, const fpos<stateT>& y);
-
-template <class stateT> bool operator==(const fpos<stateT>& x, const fpos<stateT>& y);
-template <class stateT> bool operator!=(const fpos<stateT>& x, const fpos<stateT>& y);
-
-template <class charT>
-struct char_traits
-{
-    typedef charT     char_type;
-    typedef ...       int_type;
-    typedef streamoff off_type;
-    typedef streampos pos_type;
-    typedef mbstate_t state_type;
-
-    static void assign(char_type& c1, const char_type& c2) noexcept;
-    static constexpr bool eq(char_type c1, char_type c2) noexcept;
-    static constexpr bool lt(char_type c1, char_type c2) noexcept;
-
-    static int              compare(const char_type* s1, const char_type* s2, size_t n);
-    static size_t           length(const char_type* s);
-    static const char_type* find(const char_type* s, size_t n, const char_type& a);
-    static char_type*       move(char_type* s1, const char_type* s2, size_t n);
-    static char_type*       copy(char_type* s1, const char_type* s2, size_t n);
-    static char_type*       assign(char_type* s, size_t n, char_type a);
-
-    static constexpr int_type  not_eof(int_type c) noexcept;
-    static constexpr char_type to_char_type(int_type c) noexcept;
-    static constexpr int_type  to_int_type(char_type c) noexcept;
-    static constexpr bool      eq_int_type(int_type c1, int_type c2) noexcept;
-    static constexpr int_type  eof() noexcept;
-};
-
-template <> struct char_traits<char>;
-template <> struct char_traits<wchar_t>;
-template <> struct char_traits<char8_t>;  // C++20
-template <> struct char_traits<char16_t>;
-template <> struct char_traits<char32_t>;
-
-template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
-class basic_string
-{
-public:
-// types:
-    typedef traits traits_type;
-    typedef typename traits_type::char_type value_type;
-    typedef Allocator allocator_type;
-    typedef typename allocator_type::size_type size_type;
-    typedef typename allocator_type::difference_type difference_type;
-    typedef typename allocator_type::reference reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef typename allocator_type::pointer pointer;
-    typedef typename allocator_type::const_pointer const_pointer;
-    typedef implementation-defined iterator;
-    typedef implementation-defined const_iterator;
-    typedef std::reverse_iterator<iterator> reverse_iterator;
-    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
-
-    static const size_type npos = -1;
-
-    basic_string()
-        noexcept(is_nothrow_default_constructible<allocator_type>::value);
-    explicit basic_string(const allocator_type& a);
-    basic_string(const basic_string& str);
-    basic_string(basic_string&& str)
-        noexcept(is_nothrow_move_constructible<allocator_type>::value);
-    basic_string(const basic_string& str, size_type pos,
-                 const allocator_type& a = allocator_type());
-    basic_string(const basic_string& str, size_type pos, size_type n,
-                 const Allocator& a = Allocator());
-    template<class T>
-        basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator()); // C++17
-    template <class T>
-        explicit basic_string(const T& t, const Allocator& a = Allocator()); // C++17
-    basic_string(const value_type* s, const allocator_type& a = allocator_type());
-    basic_string(const value_type* s, size_type n, const allocator_type& a = allocator_type());
-    basic_string(size_type n, value_type c, const allocator_type& a = allocator_type());
-    template<class InputIterator>
-        basic_string(InputIterator begin, InputIterator end,
-                     const allocator_type& a = allocator_type());
-    basic_string(initializer_list<value_type>, const Allocator& = Allocator());
-    basic_string(const basic_string&, const Allocator&);
-    basic_string(basic_string&&, const Allocator&);
-
-    ~basic_string();
-
-    operator basic_string_view<charT, traits>() const noexcept;
-
-    basic_string& operator=(const basic_string& str);
-    template <class T>
-        basic_string& operator=(const T& t); // C++17
-    basic_string& operator=(basic_string&& str)
-        noexcept(
-             allocator_type::propagate_on_container_move_assignment::value ||
-             allocator_type::is_always_equal::value ); // C++17
-    basic_string& operator=(const value_type* s);
-    basic_string& operator=(value_type c);
-    basic_string& operator=(initializer_list<value_type>);
-
-    iterator       begin() noexcept;
-    const_iterator begin() const noexcept;
-    iterator       end() noexcept;
-    const_iterator end() const noexcept;
-
-    reverse_iterator       rbegin() noexcept;
-    const_reverse_iterator rbegin() const noexcept;
-    reverse_iterator       rend() noexcept;
-    const_reverse_iterator rend() const noexcept;
-
-    const_iterator         cbegin() const noexcept;
-    const_iterator         cend() const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend() const noexcept;
-
-    size_type size() const noexcept;
-    size_type length() const noexcept;
-    size_type max_size() const noexcept;
-    size_type capacity() const noexcept;
-
-    void resize(size_type n, value_type c);
-    void resize(size_type n);
-
-    void reserve(size_type res_arg);
-    void reserve(); // deprecated in C++20
-    void shrink_to_fit();
-    void clear() noexcept;
-    bool empty() const noexcept;
-
-    const_reference operator[](size_type pos) const;
-    reference       operator[](size_type pos);
-
-    const_reference at(size_type n) const;
-    reference       at(size_type n);
-
-    basic_string& operator+=(const basic_string& str);
-    template <class T>
-        basic_string& operator+=(const T& t);              // C++17
-    basic_string& operator+=(const value_type* s);
-    basic_string& operator+=(value_type c);
-    basic_string& operator+=(initializer_list<value_type>);
-
-    basic_string& append(const basic_string& str);
-    template <class T>
-        basic_string& append(const T& t);                 // C++17
-    basic_string& append(const basic_string& str, size_type pos, size_type n=npos); //C++14
-    template <class T>
-        basic_string& append(const T& t, size_type pos, size_type n=npos); // C++17
-    basic_string& append(const value_type* s, size_type n);
-    basic_string& append(const value_type* s);
-    basic_string& append(size_type n, value_type c);
-    template<class InputIterator>
-        basic_string& append(InputIterator first, InputIterator last);
-    basic_string& append(initializer_list<value_type>);
-
-    void push_back(value_type c);
-    void pop_back();
-    reference       front();
-    const_reference front() const;
-    reference       back();
-    const_reference back() const;
-
-    basic_string& assign(const basic_string& str);
-    template <class T>
-        basic_string& assign(const T& t);  // C++17
-    basic_string& assign(basic_string&& str);
-    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos); // C++14
-    template <class T>
-        basic_string& assign(const T& t, size_type pos, size_type n=npos); // C++17
-    basic_string& assign(const value_type* s, size_type n);
-    basic_string& assign(const value_type* s);
-    basic_string& assign(size_type n, value_type c);
-    template<class InputIterator>
-        basic_string& assign(InputIterator first, InputIterator last);
-    basic_string& assign(initializer_list<value_type>);
-
-    basic_string& insert(size_type pos1, const basic_string& str);
-    template <class T>
-        basic_string& insert(size_type pos1, const T& t);
-    basic_string& insert(size_type pos1, const basic_string& str,
-                         size_type pos2, size_type n);
-    template <class T>
-        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17
-    basic_string& insert(size_type pos, const value_type* s, size_type n=npos); //C++14
-    basic_string& insert(size_type pos, const value_type* s);
-    basic_string& insert(size_type pos, size_type n, value_type c);
-    iterator      insert(const_iterator p, value_type c);
-    iterator      insert(const_iterator p, size_type n, value_type c);
-    template<class InputIterator>
-        iterator insert(const_iterator p, InputIterator first, InputIterator last);
-    iterator      insert(const_iterator p, initializer_list<value_type>);
-
-    basic_string& erase(size_type pos = 0, size_type n = npos);
-    iterator      erase(const_iterator position);
-    iterator      erase(const_iterator first, const_iterator last);
-
-    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
-    template <class T>
-    basic_string& replace(size_type pos1, size_type n1, const T& t);  // C++17
-    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
-                          size_type pos2, size_type n2=npos); // C++14
-    template <class T>
-        basic_string& replace(size_type pos1, size_type n1, const T& t,
-                              size_type pos2, size_type n); // C++17
-    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);
-    basic_string& replace(size_type pos, size_type n1, const value_type* s);
-    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);
-    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
-    template <class T>
-        basic_string& replace(const_iterator i1, const_iterator i2, const T& t);  // C++17
-    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n);
-    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);
-    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);
-    template<class InputIterator>
-        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
-    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);
-
-    size_type copy(value_type* s, size_type n, size_type pos = 0) const;
-    basic_string substr(size_type pos = 0, size_type n = npos) const;
-
-    void swap(basic_string& str)
-        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
-                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
-
-    const value_type* c_str() const noexcept;
-    const value_type* data() const noexcept;
-          value_type* data()       noexcept;   // C++17
-
-    allocator_type get_allocator() const noexcept;
-
-    size_type find(const basic_string& str, size_type pos = 0) const noexcept;
-    template <class T>
-        size_type find(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
-    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;
-    size_type find(const value_type* s, size_type pos = 0) const noexcept;
-    size_type find(value_type c, size_type pos = 0) const noexcept;
-
-    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;
-    template <class T>
-        size_type rfind(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
-    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;
-    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;
-    size_type rfind(value_type c, size_type pos = npos) const noexcept;
-
-    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;
-    template <class T>
-        size_type find_first_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
-    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;
-    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;
-    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;
-
-    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;
-    template <class T>
-        size_type find_last_of(const T& t, size_type pos = npos) const noexcept noexcept; // C++17, noexcept as an extension
-    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;
-    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;
-    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;
-
-    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;
-    template <class T>
-        size_type find_first_not_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
-    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
-    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;
-    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;
-
-    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;
-    template <class T>
-        size_type find_last_not_of(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
-    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
-    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;
-    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;
-
-    int compare(const basic_string& str) const noexcept;
-    template <class T>
-        int compare(const T& t) const noexcept;  // C++17, noexcept as an extension
-    int compare(size_type pos1, size_type n1, const basic_string& str) const;
-    template <class T>
-        int compare(size_type pos1, size_type n1, const T& t) const;  // C++17
-    int compare(size_type pos1, size_type n1, const basic_string& str,
-                size_type pos2, size_type n2=npos) const; // C++14
-    template <class T>
-        int compare(size_type pos1, size_type n1, const T& t,
-                    size_type pos2, size_type n2=npos) const; // C++17
-    int compare(const value_type* s) const noexcept;
-    int compare(size_type pos1, size_type n1, const value_type* s) const;
-    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;
-
-    bool starts_with(basic_string_view<charT, traits> sv) const noexcept; // C++20
-    bool starts_with(charT c) const noexcept;                             // C++20
-    bool starts_with(const charT* s) const;                               // C++20
-    bool ends_with(basic_string_view<charT, traits> sv) const noexcept;   // C++20
-    bool ends_with(charT c) const noexcept;                               // C++20
-    bool ends_with(const charT* s) const;                                 // C++20
-
-    constexpr bool contains(basic_string_view<charT, traits> sv) const noexcept; // C++2b
-    constexpr bool contains(charT c) const noexcept;                             // C++2b
-    constexpr bool contains(const charT* s) const;                               // C++2b
-
-    bool __invariants() const;
-};
-
-template<class InputIterator,
-         class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-basic_string(InputIterator, InputIterator, Allocator = Allocator())
-   -> basic_string<typename iterator_traits<InputIterator>::value_type,
-                  char_traits<typename iterator_traits<InputIterator>::value_type>,
-                  Allocator>;   // C++17
-
-template<class charT, class traits, class Allocator>
-basic_string<charT, traits, Allocator>
-operator+(const basic_string<charT, traits, Allocator>& lhs,
-          const basic_string<charT, traits, Allocator>& rhs);
-
-template<class charT, class traits, class Allocator>
-basic_string<charT, traits, Allocator>
-operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);
-
-template<class charT, class traits, class Allocator>
-basic_string<charT, traits, Allocator>
-operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
-
-template<class charT, class traits, class Allocator>
-basic_string<charT, traits, Allocator>
-operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
-
-template<class charT, class traits, class Allocator>
-basic_string<charT, traits, Allocator>
-operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
-
-template<class charT, class traits, class Allocator>
-bool operator==(const basic_string<charT, traits, Allocator>& lhs,
-                const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
-                const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator!=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator!=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator< (const basic_string<charT, traits, Allocator>& lhs,
-                const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator< (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator> (const basic_string<charT, traits, Allocator>& lhs,
-                const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator> (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator> (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator<=(const basic_string<charT, traits, Allocator>& lhs,
-                const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator<=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator<=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator>=(const basic_string<charT, traits, Allocator>& lhs,
-                const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator>=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-bool operator>=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
-
-template<class charT, class traits, class Allocator>
-void swap(basic_string<charT, traits, Allocator>& lhs,
-          basic_string<charT, traits, Allocator>& rhs)
-            noexcept(noexcept(lhs.swap(rhs)));
-
-template<class charT, class traits, class Allocator>
-basic_istream<charT, traits>&
-operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
-
-template<class charT, class traits, class Allocator>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str);
-
-template<class charT, class traits, class Allocator>
-basic_istream<charT, traits>&
-getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str,
-        charT delim);
-
-template<class charT, class traits, class Allocator>
-basic_istream<charT, traits>&
-getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
-
-template<class charT, class traits, class Allocator, class U>
-typename basic_string<charT, traits, Allocator>::size_type
-erase(basic_string<charT, traits, Allocator>& c, const U& value);    // C++20
-template<class charT, class traits, class Allocator, class Predicate>
-typename basic_string<charT, traits, Allocator>::size_type
-erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred); // C++20
-
-typedef basic_string<char>    string;
-typedef basic_string<wchar_t> wstring;
-typedef basic_string<char8_t> u8string; // C++20
-typedef basic_string<char16_t> u16string;
-typedef basic_string<char32_t> u32string;
-
-int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
-long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
-unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
-long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
-unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);
-
-float       stof (const string& str, size_t* idx = nullptr);
-double      stod (const string& str, size_t* idx = nullptr);
-long double stold(const string& str, size_t* idx = nullptr);
-
-string to_string(int val);
-string to_string(unsigned val);
-string to_string(long val);
-string to_string(unsigned long val);
-string to_string(long long val);
-string to_string(unsigned long long val);
-string to_string(float val);
-string to_string(double val);
-string to_string(long double val);
-
-int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
-long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
-unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
-long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
-unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);
-
-float       stof (const wstring& str, size_t* idx = nullptr);
-double      stod (const wstring& str, size_t* idx = nullptr);
-long double stold(const wstring& str, size_t* idx = nullptr);
-
-wstring to_wstring(int val);
-wstring to_wstring(unsigned val);
-wstring to_wstring(long val);
-wstring to_wstring(unsigned long val);
-wstring to_wstring(long long val);
-wstring to_wstring(unsigned long long val);
-wstring to_wstring(float val);
-wstring to_wstring(double val);
-wstring to_wstring(long double val);
-
-template <> struct hash<string>;
-template <> struct hash<u8string>; // C++20
-template <> struct hash<u16string>;
-template <> struct hash<u32string>;
-template <> struct hash<wstring>;
-
-basic_string<char>     operator "" s( const char *str,     size_t len ); // C++14
-basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++14
-basic_string<char8_t>  operator "" s( const char8_t *str,  size_t len ); // C++20
-basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++14
-basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++14
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/string.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -10,179 +10,7 @@
 #ifndef _LIBCPP_STRING_VIEW
 #define _LIBCPP_STRING_VIEW
 
-/*
-string_view synopsis
-
-namespace std {
-
-    // 7.2, Class template basic_string_view
-    template<class charT, class traits = char_traits<charT>>
-        class basic_string_view;
-
-    template<class charT, class traits>
-    inline constexpr bool ranges::enable_view<basic_string_view<charT, traits>> = true;
-
-    template<class charT, class traits>
-    inline constexpr bool ranges::enable_borrowed_range<basic_string_view<charT, traits>> = true;  // C++20
-
-    // 7.9, basic_string_view non-member comparison functions
-    template<class charT, class traits>
-    constexpr bool operator==(basic_string_view<charT, traits> x,
-                              basic_string_view<charT, traits> y) noexcept;
-    template<class charT, class traits>
-    constexpr bool operator!=(basic_string_view<charT, traits> x,
-                              basic_string_view<charT, traits> y) noexcept;
-    template<class charT, class traits>
-    constexpr bool operator< (basic_string_view<charT, traits> x,
-                                 basic_string_view<charT, traits> y) noexcept;
-    template<class charT, class traits>
-    constexpr bool operator> (basic_string_view<charT, traits> x,
-                              basic_string_view<charT, traits> y) noexcept;
-    template<class charT, class traits>
-    constexpr bool operator<=(basic_string_view<charT, traits> x,
-                                 basic_string_view<charT, traits> y) noexcept;
-    template<class charT, class traits>
-    constexpr bool operator>=(basic_string_view<charT, traits> x,
-                              basic_string_view<charT, traits> y) noexcept;
-    // see below, sufficient additional overloads of comparison functions
-
-    // 7.10, Inserters and extractors
-    template<class charT, class traits>
-      basic_ostream<charT, traits>&
-        operator<<(basic_ostream<charT, traits>& os,
-                   basic_string_view<charT, traits> str);
-
-    // basic_string_view typedef names
-    typedef basic_string_view<char> string_view;
-    typedef basic_string_view<char8_t> u8string_view; // C++20
-    typedef basic_string_view<char16_t> u16string_view;
-    typedef basic_string_view<char32_t> u32string_view;
-    typedef basic_string_view<wchar_t> wstring_view;
-
-    template<class charT, class traits = char_traits<charT>>
-    class basic_string_view {
-      public:
-      // types
-      typedef traits traits_type;
-      typedef charT value_type;
-      typedef charT* pointer;
-      typedef const charT* const_pointer;
-      typedef charT& reference;
-      typedef const charT& const_reference;
-      typedef implementation-defined const_iterator;
-      typedef const_iterator iterator;
-      typedef reverse_iterator<const_iterator> const_reverse_iterator;
-      typedef const_reverse_iterator reverse_iterator;
-      typedef size_t size_type;
-      typedef ptrdiff_t difference_type;
-      static constexpr size_type npos = size_type(-1);
-
-      // 7.3, basic_string_view constructors and assignment operators
-      constexpr basic_string_view() noexcept;
-      constexpr basic_string_view(const basic_string_view&) noexcept = default;
-      basic_string_view& operator=(const basic_string_view&) noexcept = default;
-      template<class Allocator>
-      constexpr basic_string_view(const charT* str);
-      constexpr basic_string_view(const charT* str, size_type len);
-
-      // 7.4, basic_string_view iterator support
-      constexpr const_iterator begin() const noexcept;
-      constexpr const_iterator end() const noexcept;
-      constexpr const_iterator cbegin() const noexcept;
-      constexpr const_iterator cend() const noexcept;
-      const_reverse_iterator rbegin() const noexcept;
-      const_reverse_iterator rend() const noexcept;
-      const_reverse_iterator crbegin() const noexcept;
-      const_reverse_iterator crend() const noexcept;
-
-      // 7.5, basic_string_view capacity
-      constexpr size_type size() const noexcept;
-      constexpr size_type length() const noexcept;
-      constexpr size_type max_size() const noexcept;
-      constexpr bool empty() const noexcept;
-
-      // 7.6, basic_string_view element access
-      constexpr const_reference operator[](size_type pos) const;
-      constexpr const_reference at(size_type pos) const;
-      constexpr const_reference front() const;
-      constexpr const_reference back() const;
-      constexpr const_pointer data() const noexcept;
-
-      // 7.7, basic_string_view modifiers
-      constexpr void remove_prefix(size_type n);
-      constexpr void remove_suffix(size_type n);
-      constexpr void swap(basic_string_view& s) noexcept;
-
-      size_type copy(charT* s, size_type n, size_type pos = 0) const;  // constexpr in C++20
-
-      constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
-      constexpr int compare(basic_string_view s) const noexcept;
-      constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
-      constexpr int compare(size_type pos1, size_type n1,
-                            basic_string_view s, size_type pos2, size_type n2) const;
-      constexpr int compare(const charT* s) const;
-      constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
-      constexpr int compare(size_type pos1, size_type n1,
-                            const charT* s, size_type n2) const;
-      constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
-      constexpr size_type find(charT c, size_type pos = 0) const noexcept;
-      constexpr size_type find(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
-      constexpr size_type find(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
-      constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept;
-      constexpr size_type rfind(charT c, size_type pos = npos) const noexcept;
-      constexpr size_type rfind(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
-      constexpr size_type rfind(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
-      constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const noexcept;
-      constexpr size_type find_first_of(charT c, size_type pos = 0) const noexcept;
-      constexpr size_type find_first_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
-      constexpr size_type find_first_of(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
-      constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const noexcept;
-      constexpr size_type find_last_of(charT c, size_type pos = npos) const noexcept;
-      constexpr size_type find_last_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
-      constexpr size_type find_last_of(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
-      constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const noexcept;
-      constexpr size_type find_first_not_of(charT c, size_type pos = 0) const noexcept;
-      constexpr size_type find_first_not_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
-      constexpr size_type find_first_not_of(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
-      constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const noexcept;
-      constexpr size_type find_last_not_of(charT c, size_type pos = npos) const noexcept;
-      constexpr size_type find_last_not_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
-      constexpr size_type find_last_not_of(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
-
-      constexpr bool starts_with(basic_string_view s) const noexcept; // C++20
-      constexpr bool starts_with(charT c) const noexcept;             // C++20
-      constexpr bool starts_with(const charT* s) const;               // C++20
-      constexpr bool ends_with(basic_string_view s) const noexcept;   // C++20
-      constexpr bool ends_with(charT c) const noexcept;               // C++20
-      constexpr bool ends_with(const charT* s) const;                 // C++20
-
-      constexpr bool contains(basic_string_view s) const noexcept; // C++2b
-      constexpr bool contains(charT c) const noexcept;             // C++2b
-      constexpr bool contains(const charT* s) const;               // C++2b
-
-     private:
-      const_pointer data_;  // exposition only
-      size_type     size_;  // exposition only
-    };
-
-  // 7.11, Hash support
-  template <class T> struct hash;
-  template <> struct hash<string_view>;
-  template <> struct hash<u8string_view>; // C++20
-  template <> struct hash<u16string_view>;
-  template <> struct hash<u32string_view>;
-  template <> struct hash<wstring_view>;
-
-  constexpr basic_string_view<char>     operator "" sv( const char *str,     size_t len ) noexcept;
-  constexpr basic_string_view<wchar_t>  operator "" sv( const wchar_t *str,  size_t len ) noexcept;
-  constexpr basic_string_view<char8_t>  operator "" sv( const char8_t *str,  size_t len ) noexcept; // C++20
-  constexpr basic_string_view<char16_t> operator "" sv( const char16_t *str, size_t len ) noexcept;
-  constexpr basic_string_view<char32_t> operator "" sv( const char32_t *str, size_t len ) noexcept;
-
-}  // namespace std
-
-
-*/
+// Synopsis avaiable at http://wg21.link/string.view.synop.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/strstream b/libcxx/include/strstream
--- a/libcxx/include/strstream
+++ b/libcxx/include/strstream
@@ -10,124 +10,7 @@
 #ifndef _LIBCPP_STRSTREAM
 #define _LIBCPP_STRSTREAM
 
-/*
-    strstream synopsis
-
-class strstreambuf
-    : public basic_streambuf<char>
-{
-public:
-    explicit strstreambuf(streamsize alsize_arg = 0); // before C++20
-    strstreambuf() : strstreambuf(0) {}               // C++20
-    explicit strstreambuf(streamsize alsize_arg);     // C++20
-
-    strstreambuf(void* (*palloc_arg)(size_t), void (*pfree_arg)(void*));
-    strstreambuf(char* gnext_arg, streamsize n, char* pbeg_arg = nullptr);
-    strstreambuf(const char* gnext_arg, streamsize n);
-
-    strstreambuf(signed char* gnext_arg, streamsize n, signed char* pbeg_arg = nullptr);
-    strstreambuf(const signed char* gnext_arg, streamsize n);
-    strstreambuf(unsigned char* gnext_arg, streamsize n, unsigned char* pbeg_arg = nullptr);
-    strstreambuf(const unsigned char* gnext_arg, streamsize n);
-
-    strstreambuf(strstreambuf&& rhs);
-    strstreambuf& operator=(strstreambuf&& rhs);
-
-    virtual ~strstreambuf();
-
-    void swap(strstreambuf& rhs);
-
-    void freeze(bool freezefl = true);
-    char* str();
-    int pcount() const;
-
-protected:
-    virtual int_type overflow (int_type c = EOF);
-    virtual int_type pbackfail(int_type c = EOF);
-    virtual int_type underflow();
-    virtual pos_type seekoff(off_type off, ios_base::seekdir way,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual pos_type seekpos(pos_type sp,
-                             ios_base::openmode which = ios_base::in | ios_base::out);
-    virtual streambuf* setbuf(char* s, streamsize n);
-
-private:
-    typedef T1 strstate;                // exposition only
-    static const strstate allocated;    // exposition only
-    static const strstate constant;     // exposition only
-    static const strstate dynamic;      // exposition only
-    static const strstate frozen;       // exposition only
-    strstate strmode;                   // exposition only
-    streamsize alsize;                  // exposition only
-    void* (*palloc)(size_t);            // exposition only
-    void (*pfree)(void*);               // exposition only
-};
-
-class istrstream
-    : public basic_istream<char>
-{
-public:
-    explicit istrstream(const char* s);
-    explicit istrstream(char* s);
-    istrstream(const char* s, streamsize n);
-    istrstream(char* s, streamsize n);
-
-    virtual ~istrstream();
-
-    strstreambuf* rdbuf() const;
-    char *str();
-
-private:
-    strstreambuf sb; // exposition only
-};
-
-class ostrstream
-    : public basic_ostream<char>
-{
-public:
-    ostrstream();
-    ostrstream(char* s, int n, ios_base::openmode mode = ios_base::out);
-
-    virtual ~ostrstream();
-
-    strstreambuf* rdbuf() const;
-    void freeze(bool freezefl = true);
-    char* str();
-    int pcount() const;
-
-private:
-    strstreambuf sb; // exposition only
-};
-
-class strstream
-    : public basic_iostream<char>
-{
-public:
-    // Types
-    typedef char                        char_type;
-    typedef char_traits<char>::int_type int_type;
-    typedef char_traits<char>::pos_type pos_type;
-    typedef char_traits<char>::off_type off_type;
-
-    // constructors/destructor
-    strstream();
-    strstream(char* s, int n, ios_base::openmode mode = ios_base::in | ios_base::out);
-
-    virtual ~strstream();
-
-    // Members:
-    strstreambuf* rdbuf() const;
-    void freeze(bool freezefl = true);
-    int pcount() const;
-    char* str();
-
-private:
-    strstreambuf sb; // exposition only
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/depr.strstream.syn.
 
 #include <__config>
 #include <istream>
diff --git a/libcxx/include/system_error b/libcxx/include/system_error
--- a/libcxx/include/system_error
+++ b/libcxx/include/system_error
@@ -10,137 +10,7 @@
 #ifndef _LIBCPP_SYSTEM_ERROR
 #define _LIBCPP_SYSTEM_ERROR
 
-/*
-    system_error synopsis
-
-namespace std
-{
-
-class error_category
-{
-public:
-    virtual ~error_category() noexcept;
-
-    constexpr error_category();
-    error_category(const error_category&) = delete;
-    error_category& operator=(const error_category&) = delete;
-
-    virtual const char* name() const noexcept = 0;
-    virtual error_condition default_error_condition(int ev) const noexcept;
-    virtual bool equivalent(int code, const error_condition& condition) const noexcept;
-    virtual bool equivalent(const error_code& code, int condition) const noexcept;
-    virtual string message(int ev) const = 0;
-
-    bool operator==(const error_category& rhs) const noexcept;
-    bool operator!=(const error_category& rhs) const noexcept;
-    bool operator<(const error_category& rhs) const noexcept;
-};
-
-const error_category& generic_category() noexcept;
-const error_category& system_category() noexcept;
-
-template <class T> struct is_error_code_enum
-    : public false_type {};
-
-template <class T> struct is_error_condition_enum
-    : public false_type {};
-
-template <class _Tp>
-inline constexpr size_t is_error_condition_enum_v = is_error_condition_enum<_Tp>::value; // C++17
-
-template <class _Tp>
-inline constexpr size_t is_error_code_enum_v = is_error_code_enum<_Tp>::value; // C++17
-
-class error_code
-{
-public:
-    // constructors:
-    error_code() noexcept;
-    error_code(int val, const error_category& cat) noexcept;
-    template <class ErrorCodeEnum>
-        error_code(ErrorCodeEnum e) noexcept;
-
-    // modifiers:
-    void assign(int val, const error_category& cat) noexcept;
-    template <class ErrorCodeEnum>
-        error_code& operator=(ErrorCodeEnum e) noexcept;
-    void clear() noexcept;
-
-    // observers:
-    int value() const noexcept;
-    const error_category& category() const noexcept;
-    error_condition default_error_condition() const noexcept;
-    string message() const;
-    explicit operator bool() const noexcept;
-};
-
-// non-member functions:
-bool operator<(const error_code& lhs, const error_code& rhs) noexcept;
-template <class charT, class traits>
-    basic_ostream<charT,traits>&
-    operator<<(basic_ostream<charT,traits>& os, const error_code& ec);
-
-class error_condition
-{
-public:
-    // constructors:
-    error_condition() noexcept;
-    error_condition(int val, const error_category& cat) noexcept;
-    template <class ErrorConditionEnum>
-        error_condition(ErrorConditionEnum e) noexcept;
-
-    // modifiers:
-    void assign(int val, const error_category& cat) noexcept;
-    template <class ErrorConditionEnum>
-        error_condition& operator=(ErrorConditionEnum e) noexcept;
-    void clear() noexcept;
-
-    // observers:
-    int value() const noexcept;
-    const error_category& category() const noexcept;
-    string message() const noexcept;
-    explicit operator bool() const noexcept;
-};
-
-bool operator<(const error_condition& lhs, const error_condition& rhs) noexcept;
-
-class system_error
-    : public runtime_error
-{
-public:
-    system_error(error_code ec, const string& what_arg);
-    system_error(error_code ec, const char* what_arg);
-    system_error(error_code ec);
-    system_error(int ev, const error_category& ecat, const string& what_arg);
-    system_error(int ev, const error_category& ecat, const char* what_arg);
-    system_error(int ev, const error_category& ecat);
-
-    const error_code& code() const noexcept;
-    const char* what() const noexcept;
-};
-
-template <> struct is_error_condition_enum<errc>
-    : true_type { }
-
-error_code make_error_code(errc e) noexcept;
-error_condition make_error_condition(errc e) noexcept;
-
-// Comparison operators:
-bool operator==(const error_code& lhs, const error_code& rhs) noexcept;
-bool operator==(const error_code& lhs, const error_condition& rhs) noexcept;
-bool operator==(const error_condition& lhs, const error_code& rhs) noexcept;
-bool operator==(const error_condition& lhs, const error_condition& rhs) noexcept;
-bool operator!=(const error_code& lhs, const error_code& rhs) noexcept;
-bool operator!=(const error_code& lhs, const error_condition& rhs) noexcept;
-bool operator!=(const error_condition& lhs, const error_code& rhs) noexcept;
-bool operator!=(const error_condition& lhs, const error_condition& rhs) noexcept;
-
-template <> struct hash<std::error_code>;
-template <> struct hash<std::error_condition>;
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/system.error.syn.
 
 #include <__config>
 #include <__errc>
diff --git a/libcxx/include/thread b/libcxx/include/thread
--- a/libcxx/include/thread
+++ b/libcxx/include/thread
@@ -10,77 +10,7 @@
 #ifndef _LIBCPP_THREAD
 #define _LIBCPP_THREAD
 
-/*
-
-    thread synopsis
-
-namespace std
-{
-
-class thread
-{
-public:
-    class id;
-    typedef pthread_t native_handle_type;
-
-    thread() noexcept;
-    template <class F, class ...Args> explicit thread(F&& f, Args&&... args);
-    ~thread();
-
-    thread(const thread&) = delete;
-    thread(thread&& t) noexcept;
-
-    thread& operator=(const thread&) = delete;
-    thread& operator=(thread&& t) noexcept;
-
-    void swap(thread& t) noexcept;
-
-    bool joinable() const noexcept;
-    void join();
-    void detach();
-    id get_id() const noexcept;
-    native_handle_type native_handle();
-
-    static unsigned hardware_concurrency() noexcept;
-};
-
-void swap(thread& x, thread& y) noexcept;
-
-class thread::id
-{
-public:
-    id() noexcept;
-};
-
-bool operator==(thread::id x, thread::id y) noexcept;
-bool operator!=(thread::id x, thread::id y) noexcept;
-bool operator< (thread::id x, thread::id y) noexcept;
-bool operator<=(thread::id x, thread::id y) noexcept;
-bool operator> (thread::id x, thread::id y) noexcept;
-bool operator>=(thread::id x, thread::id y) noexcept;
-
-template<class charT, class traits>
-basic_ostream<charT, traits>&
-operator<<(basic_ostream<charT, traits>& out, thread::id id);
-
-namespace this_thread
-{
-
-thread::id get_id() noexcept;
-
-void yield() noexcept;
-
-template <class Clock, class Duration>
-void sleep_until(const chrono::time_point<Clock, Duration>& abs_time);
-
-template <class Rep, class Period>
-void sleep_for(const chrono::duration<Rep, Period>& rel_time);
-
-}  // this_thread
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/thread.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -10,144 +10,7 @@
 #ifndef _LIBCPP_TUPLE
 #define _LIBCPP_TUPLE
 
-/*
-    tuple synopsis
-
-namespace std
-{
-
-template <class... T>
-class tuple {
-public:
-    explicit(see-below) constexpr tuple();
-    explicit(see-below) tuple(const T&...);  // constexpr in C++14
-    template <class... U>
-        explicit(see-below) tuple(U&&...);  // constexpr in C++14
-    tuple(const tuple&) = default;
-    tuple(tuple&&) = default;
-    template <class... U>
-        explicit(see-below) tuple(const tuple<U...>&);  // constexpr in C++14
-    template <class... U>
-        explicit(see-below) tuple(tuple<U...>&&);  // constexpr in C++14
-    template <class U1, class U2>
-        explicit(see-below) tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2 // constexpr in C++14
-    template <class U1, class U2>
-        explicit(see-below) tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2  // constexpr in C++14
-
-    // allocator-extended constructors
-    template <class Alloc>
-        tuple(allocator_arg_t, const Alloc& a);
-    template <class Alloc>
-        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const T&...);          // constexpr in C++20
-    template <class Alloc, class... U>
-        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, U&&...);               // constexpr in C++20
-    template <class Alloc>
-        tuple(allocator_arg_t, const Alloc& a, const tuple&);                             // constexpr in C++20
-    template <class Alloc>
-        tuple(allocator_arg_t, const Alloc& a, tuple&&);                                  // constexpr in C++20
-    template <class Alloc, class... U>
-        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);   // constexpr in C++20
-    template <class Alloc, class... U>
-        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);        // constexpr in C++20
-    template <class Alloc, class U1, class U2>
-        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);  // constexpr in C++20
-    template <class Alloc, class U1, class U2>
-        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);       // constexpr in C++20
-
-    tuple& operator=(const tuple&);                                                       // constexpr in C++20
-    tuple& operator=(tuple&&) noexcept(is_nothrow_move_assignable_v<T> && ...);           // constexpr in C++20
-    template <class... U>
-        tuple& operator=(const tuple<U...>&);                                             // constexpr in C++20
-    template <class... U>
-        tuple& operator=(tuple<U...>&&);                                                  // constexpr in C++20
-    template <class U1, class U2>
-        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2                   // constexpr in C++20
-    template <class U1, class U2>
-        tuple& operator=(pair<U1, U2>&&); // iff sizeof...(T) == 2                        // constexpr in C++20
-
-    template<class U, size_t N>
-        tuple& operator=(array<U, N> const&) // iff sizeof...(T) == N, EXTENSION
-    template<class U, size_t N>
-        tuple& operator=(array<U, N>&&) // iff sizeof...(T) == N, EXTENSION
-
-    void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));               // constexpr in C++20
-};
-
-template <class ...T>
-tuple(T...) -> tuple<T...>;                                         // since C++17
-template <class T1, class T2>
-tuple(pair<T1, T2>) -> tuple<T1, T2>;                               // since C++17
-template <class Alloc, class ...T>
-tuple(allocator_arg_t, Alloc, T...) -> tuple<T...>;                 // since C++17
-template <class Alloc, class T1, class T2>
-tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>;       // since C++17
-template <class Alloc, class ...T>
-tuple(allocator_arg_t, Alloc, tuple<T...>) -> tuple<T...>;          // since C++17
-
-inline constexpr unspecified ignore;
-
-template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
-template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
-template <class... T> tuple<T&...> tie(T&...) noexcept; // constexpr in C++14
-template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
-
-// [tuple.apply], calling a function with a tuple of arguments:
-template <class F, class Tuple>
-  constexpr decltype(auto) apply(F&& f, Tuple&& t); // C++17
-template <class T, class Tuple>
-  constexpr T make_from_tuple(Tuple&& t); // C++17
-
-// 20.4.1.4, tuple helper classes:
-template <class T> struct tuple_size; // undefined
-template <class... T> struct tuple_size<tuple<T...>>;
-template <class T>
- inline constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17
-template <size_t I, class T> struct tuple_element; // undefined
-template <size_t I, class... T> struct tuple_element<I, tuple<T...>>;
-template <size_t I, class T>
-  using tuple_element_t = typename tuple_element <I, T>::type; // C++14
-
-// 20.4.1.5, element access:
-template <size_t I, class... T>
-    typename tuple_element<I, tuple<T...>>::type&
-    get(tuple<T...>&) noexcept; // constexpr in C++14
-template <size_t I, class... T>
-    const typename tuple_element<I, tuple<T...>>::type&
-    get(const tuple<T...>&) noexcept; // constexpr in C++14
-template <size_t I, class... T>
-    typename tuple_element<I, tuple<T...>>::type&&
-    get(tuple<T...>&&) noexcept; // constexpr in C++14
-template <size_t I, class... T>
-    const typename tuple_element<I, tuple<T...>>::type&&
-    get(const tuple<T...>&&) noexcept; // constexpr in C++14
-
-template <class T1, class... T>
-    constexpr T1& get(tuple<T...>&) noexcept;  // C++14
-template <class T1, class... T>
-    constexpr const T1& get(const tuple<T...>&) noexcept;   // C++14
-template <class T1, class... T>
-    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
-template <class T1, class... T>
-    constexpr const T1&& get(const tuple<T...>&&) noexcept;   // C++14
-
-// 20.4.1.6, relational operators:
-template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
-template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
-template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
-template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14
-template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
-template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
-
-template <class... Types, class Alloc>
-  struct uses_allocator<tuple<Types...>, Alloc>;
-
-template <class... Types>
-  void
-  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/tuple.syn.
 
 #include <__config>
 #include <__functional_base>
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -10,412 +10,8 @@
 #ifndef _LIBCPP_TYPE_TRAITS
 #define _LIBCPP_TYPE_TRAITS
 
-/*
-    type_traits synopsis
-
-namespace std
-{
-
-    // helper class:
-    template <class T, T v> struct integral_constant;
-    typedef integral_constant<bool, true>  true_type;   // C++11
-    typedef integral_constant<bool, false> false_type;  // C++11
-
-    template <bool B>                                   // C++14
-    using bool_constant = integral_constant<bool, B>;   // C++14
-    typedef bool_constant<true> true_type;              // C++14
-    typedef bool_constant<false> false_type;            // C++14
-
-    // helper traits
-    template <bool, class T = void> struct enable_if;
-    template <bool, class T, class F> struct conditional;
-
-    // Primary classification traits:
-    template <class T> struct is_void;
-    template <class T> struct is_null_pointer;  // C++14
-    template <class T> struct is_integral;
-    template <class T> struct is_floating_point;
-    template <class T> struct is_array;
-    template <class T> struct is_pointer;
-    template <class T> struct is_lvalue_reference;
-    template <class T> struct is_rvalue_reference;
-    template <class T> struct is_member_object_pointer;
-    template <class T> struct is_member_function_pointer;
-    template <class T> struct is_enum;
-    template <class T> struct is_union;
-    template <class T> struct is_class;
-    template <class T> struct is_function;
-
-    // Secondary classification traits:
-    template <class T> struct is_reference;
-    template <class T> struct is_arithmetic;
-    template <class T> struct is_fundamental;
-    template <class T> struct is_member_pointer;
-    template <class T> struct is_scoped_enum; // C++2b
-    template <class T> struct is_scalar;
-    template <class T> struct is_object;
-    template <class T> struct is_compound;
-
-    // Const-volatile properties and transformations:
-    template <class T> struct is_const;
-    template <class T> struct is_volatile;
-    template <class T> struct remove_const;
-    template <class T> struct remove_volatile;
-    template <class T> struct remove_cv;
-    template <class T> struct add_const;
-    template <class T> struct add_volatile;
-    template <class T> struct add_cv;
-
-    // Reference transformations:
-    template <class T> struct remove_reference;
-    template <class T> struct add_lvalue_reference;
-    template <class T> struct add_rvalue_reference;
-
-    // Pointer transformations:
-    template <class T> struct remove_pointer;
-    template <class T> struct add_pointer;
-
-    template<class T> struct type_identity;                     // C++20
-    template<class T>
-      using type_identity_t = typename type_identity<T>::type;  // C++20
-
-    // Integral properties:
-    template <class T> struct is_signed;
-    template <class T> struct is_unsigned;
-    template <class T> struct make_signed;
-    template <class T> struct make_unsigned;
-
-    // Array properties and transformations:
-    template <class T> struct rank;
-    template <class T, unsigned I = 0> struct extent;
-    template <class T> struct remove_extent;
-    template <class T> struct remove_all_extents;
-
-    template <class T> struct is_bounded_array;                 // C++20
-    template <class T> struct is_unbounded_array;               // C++20
-
-    // Member introspection:
-    template <class T> struct is_pod;
-    template <class T> struct is_trivial;
-    template <class T> struct is_trivially_copyable;
-    template <class T> struct is_standard_layout;
-    template <class T> struct is_literal_type;
-    template <class T> struct is_empty;
-    template <class T> struct is_polymorphic;
-    template <class T> struct is_abstract;
-    template <class T> struct is_final; // C++14
-    template <class T> struct is_aggregate; // C++17
-
-    template <class T, class... Args> struct is_constructible;
-    template <class T>                struct is_default_constructible;
-    template <class T>                struct is_copy_constructible;
-    template <class T>                struct is_move_constructible;
-    template <class T, class U>       struct is_assignable;
-    template <class T>                struct is_copy_assignable;
-    template <class T>                struct is_move_assignable;
-    template <class T, class U>       struct is_swappable_with;       // C++17
-    template <class T>                struct is_swappable;            // C++17
-    template <class T>                struct is_destructible;
-
-    template <class T, class... Args> struct is_trivially_constructible;
-    template <class T>                struct is_trivially_default_constructible;
-    template <class T>                struct is_trivially_copy_constructible;
-    template <class T>                struct is_trivially_move_constructible;
-    template <class T, class U>       struct is_trivially_assignable;
-    template <class T>                struct is_trivially_copy_assignable;
-    template <class T>                struct is_trivially_move_assignable;
-    template <class T>                struct is_trivially_destructible;
-
-    template <class T, class... Args> struct is_nothrow_constructible;
-    template <class T>                struct is_nothrow_default_constructible;
-    template <class T>                struct is_nothrow_copy_constructible;
-    template <class T>                struct is_nothrow_move_constructible;
-    template <class T, class U>       struct is_nothrow_assignable;
-    template <class T>                struct is_nothrow_copy_assignable;
-    template <class T>                struct is_nothrow_move_assignable;
-    template <class T, class U>       struct is_nothrow_swappable_with; // C++17
-    template <class T>                struct is_nothrow_swappable;      // C++17
-    template <class T>                struct is_nothrow_destructible;
-
-    template <class T> struct has_virtual_destructor;
-
-    template<class T> struct has_unique_object_representations;         // C++17
-
-    // Relationships between types:
-    template <class T, class U> struct is_same;
-    template <class Base, class Derived> struct is_base_of;
-
-    template <class From, class To> struct is_convertible;
-    template <typename From, typename To> struct is_nothrow_convertible;                  // C++20
-    template <typename From, typename To> inline constexpr bool is_nothrow_convertible_v; // C++20
-
-    template <class Fn, class... ArgTypes> struct is_invocable;
-    template <class R, class Fn, class... ArgTypes> struct is_invocable_r;
-
-    template <class Fn, class... ArgTypes> struct is_nothrow_invocable;
-    template <class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r;
-
-    // Alignment properties and transformations:
-    template <class T> struct alignment_of;
-    template <size_t Len, size_t Align = most_stringent_alignment_requirement>
-        struct aligned_storage;
-    template <size_t Len, class... Types> struct aligned_union;
-    template <class T> struct remove_cvref; // C++20
-
-    template <class T> struct decay;
-    template <class... T> struct common_type;
-    template <class T> struct underlying_type;
-    template <class> class result_of; // undefined
-    template <class Fn, class... ArgTypes> class result_of<Fn(ArgTypes...)>;
-    template <class Fn, class... ArgTypes> struct invoke_result;  // C++17
-
-    // const-volatile modifications:
-    template <class T>
-      using remove_const_t    = typename remove_const<T>::type;  // C++14
-    template <class T>
-      using remove_volatile_t = typename remove_volatile<T>::type;  // C++14
-    template <class T>
-      using remove_cv_t       = typename remove_cv<T>::type;  // C++14
-    template <class T>
-      using add_const_t       = typename add_const<T>::type;  // C++14
-    template <class T>
-      using add_volatile_t    = typename add_volatile<T>::type;  // C++14
-    template <class T>
-      using add_cv_t          = typename add_cv<T>::type;  // C++14
-
-    // reference modifications:
-    template <class T>
-      using remove_reference_t     = typename remove_reference<T>::type;  // C++14
-    template <class T>
-      using add_lvalue_reference_t = typename add_lvalue_reference<T>::type;  // C++14
-    template <class T>
-      using add_rvalue_reference_t = typename add_rvalue_reference<T>::type;  // C++14
-
-    // sign modifications:
-    template <class T>
-      using make_signed_t   = typename make_signed<T>::type;  // C++14
-    template <class T>
-      using make_unsigned_t = typename make_unsigned<T>::type;  // C++14
-
-    // array modifications:
-    template <class T>
-      using remove_extent_t      = typename remove_extent<T>::type;  // C++14
-    template <class T>
-      using remove_all_extents_t = typename remove_all_extents<T>::type;  // C++14
-
-    template <class T>
-      inline constexpr bool is_bounded_array_v
-        = is_bounded_array<T>::value;                                     // C++20
-      inline constexpr bool is_unbounded_array_v
-        = is_unbounded_array<T>::value;                                   // C++20
-
-    // pointer modifications:
-    template <class T>
-      using remove_pointer_t = typename remove_pointer<T>::type;  // C++14
-    template <class T>
-      using add_pointer_t    = typename add_pointer<T>::type;  // C++14
-
-    // other transformations:
-    template <size_t Len, size_t Align=default-alignment>
-      using aligned_storage_t = typename aligned_storage<Len,Align>::type;  // C++14
-    template <size_t Len, class... Types>
-      using aligned_union_t   = typename aligned_union<Len,Types...>::type;  // C++14
-    template <class T>
-      using remove_cvref_t    = typename remove_cvref<T>::type;  // C++20
-    template <class T>
-      using decay_t           = typename decay<T>::type;  // C++14
-    template <bool b, class T=void>
-      using enable_if_t       = typename enable_if<b,T>::type;  // C++14
-    template <bool b, class T, class F>
-      using conditional_t     = typename conditional<b,T,F>::type;  // C++14
-    template <class... T>
-      using common_type_t     = typename common_type<T...>::type;  // C++14
-    template <class T>
-      using underlying_type_t = typename underlying_type<T>::type;  // C++14
-    template <class T>
-      using result_of_t       = typename result_of<T>::type;  // C++14
-    template <class Fn, class... ArgTypes>
-      using invoke_result_t   = typename invoke_result<Fn, ArgTypes...>::type;  // C++17
-
-    template <class...>
-      using void_t = void;   // C++17
-
-      // See C++14 20.10.4.1, primary type categories
-      template <class T> inline constexpr bool is_void_v
-        = is_void<T>::value;                                             // C++17
-      template <class T> inline constexpr bool is_null_pointer_v
-        = is_null_pointer<T>::value;                                     // C++17
-      template <class T> inline constexpr bool is_integral_v
-        = is_integral<T>::value;                                         // C++17
-      template <class T> inline constexpr bool is_floating_point_v
-        = is_floating_point<T>::value;                                   // C++17
-      template <class T> inline constexpr bool is_array_v
-        = is_array<T>::value;                                            // C++17
-      template <class T> inline constexpr bool is_pointer_v
-        = is_pointer<T>::value;                                          // C++17
-      template <class T> inline constexpr bool is_lvalue_reference_v
-        = is_lvalue_reference<T>::value;                                 // C++17
-      template <class T> inline constexpr bool is_rvalue_reference_v
-        = is_rvalue_reference<T>::value;                                 // C++17
-      template <class T> inline constexpr bool is_member_object_pointer_v
-        = is_member_object_pointer<T>::value;                            // C++17
-      template <class T> inline constexpr bool is_member_function_pointer_v
-        = is_member_function_pointer<T>::value;                          // C++17
-      template <class T> inline constexpr bool is_enum_v
-        = is_enum<T>::value;                                             // C++17
-      template <class T> inline constexpr bool is_union_v
-        = is_union<T>::value;                                            // C++17
-      template <class T> inline constexpr bool is_class_v
-        = is_class<T>::value;                                            // C++17
-      template <class T> inline constexpr bool is_function_v
-        = is_function<T>::value;                                         // C++17
-
-      // See C++14 20.10.4.2, composite type categories
-      template <class T> inline constexpr bool is_reference_v
-        = is_reference<T>::value;                                        // C++17
-      template <class T> inline constexpr bool is_arithmetic_v
-        = is_arithmetic<T>::value;                                       // C++17
-      template <class T> inline constexpr bool is_fundamental_v
-        = is_fundamental<T>::value;                                      // C++17
-      template <class T> inline constexpr bool is_object_v
-        = is_object<T>::value;                                           // C++17
-      template <class T> inline constexpr bool is_scalar_v
-        = is_scalar<T>::value;                                           // C++17
-      template <class T> inline constexpr bool is_compound_v
-        = is_compound<T>::value;                                         // C++17
-      template <class T> inline constexpr bool is_member_pointer_v
-        = is_member_pointer<T>::value;                                   // C++17
-      template <class T> inline constexpr bool is_scoped_enum_v
-        = is_scoped_enum<T>::value;                                      // C++2b
-
-      // See C++14 20.10.4.3, type properties
-      template <class T> inline constexpr bool is_const_v
-        = is_const<T>::value;                                            // C++17
-      template <class T> inline constexpr bool is_volatile_v
-        = is_volatile<T>::value;                                         // C++17
-      template <class T> inline constexpr bool is_trivial_v
-        = is_trivial<T>::value;                                          // C++17
-      template <class T> inline constexpr bool is_trivially_copyable_v
-        = is_trivially_copyable<T>::value;                               // C++17
-      template <class T> inline constexpr bool is_standard_layout_v
-        = is_standard_layout<T>::value;                                  // C++17
-      template <class T> inline constexpr bool is_pod_v
-        = is_pod<T>::value;                                              // C++17
-      template <class T> inline constexpr bool is_literal_type_v
-        = is_literal_type<T>::value;                                     // C++17
-      template <class T> inline constexpr bool is_empty_v
-        = is_empty<T>::value;                                            // C++17
-      template <class T> inline constexpr bool is_polymorphic_v
-        = is_polymorphic<T>::value;                                      // C++17
-      template <class T> inline constexpr bool is_abstract_v
-        = is_abstract<T>::value;                                         // C++17
-      template <class T> inline constexpr bool is_final_v
-        = is_final<T>::value;                                            // C++17
-      template <class T> inline constexpr bool is_aggregate_v
-        = is_aggregate<T>::value;                                        // C++17
-      template <class T> inline constexpr bool is_signed_v
-        = is_signed<T>::value;                                           // C++17
-      template <class T> inline constexpr bool is_unsigned_v
-        = is_unsigned<T>::value;                                         // C++17
-      template <class T, class... Args> inline constexpr bool is_constructible_v
-        = is_constructible<T, Args...>::value;                           // C++17
-      template <class T> inline constexpr bool is_default_constructible_v
-        = is_default_constructible<T>::value;                            // C++17
-      template <class T> inline constexpr bool is_copy_constructible_v
-        = is_copy_constructible<T>::value;                               // C++17
-      template <class T> inline constexpr bool is_move_constructible_v
-        = is_move_constructible<T>::value;                               // C++17
-      template <class T, class U> inline constexpr bool is_assignable_v
-        = is_assignable<T, U>::value;                                    // C++17
-      template <class T> inline constexpr bool is_copy_assignable_v
-        = is_copy_assignable<T>::value;                                  // C++17
-      template <class T> inline constexpr bool is_move_assignable_v
-        = is_move_assignable<T>::value;                                  // C++17
-      template <class T, class U> inline constexpr bool is_swappable_with_v
-        = is_swappable_with<T, U>::value;                                // C++17
-      template <class T> inline constexpr bool is_swappable_v
-        = is_swappable<T>::value;                                        // C++17
-      template <class T> inline constexpr bool is_destructible_v
-        = is_destructible<T>::value;                                     // C++17
-      template <class T, class... Args> inline constexpr bool is_trivially_constructible_v
-        = is_trivially_constructible<T, Args...>::value;                 // C++17
-      template <class T> inline constexpr bool is_trivially_default_constructible_v
-        = is_trivially_default_constructible<T>::value;                  // C++17
-      template <class T> inline constexpr bool is_trivially_copy_constructible_v
-        = is_trivially_copy_constructible<T>::value;                     // C++17
-      template <class T> inline constexpr bool is_trivially_move_constructible_v
-        = is_trivially_move_constructible<T>::value;                     // C++17
-      template <class T, class U> inline constexpr bool is_trivially_assignable_v
-        = is_trivially_assignable<T, U>::value;                          // C++17
-      template <class T> inline constexpr bool is_trivially_copy_assignable_v
-        = is_trivially_copy_assignable<T>::value;                        // C++17
-      template <class T> inline constexpr bool is_trivially_move_assignable_v
-        = is_trivially_move_assignable<T>::value;                        // C++17
-      template <class T> inline constexpr bool is_trivially_destructible_v
-        = is_trivially_destructible<T>::value;                           // C++17
-      template <class T, class... Args> inline constexpr bool is_nothrow_constructible_v
-        = is_nothrow_constructible<T, Args...>::value;                   // C++17
-      template <class T> inline constexpr bool is_nothrow_default_constructible_v
-        = is_nothrow_default_constructible<T>::value;                    // C++17
-      template <class T> inline constexpr bool is_nothrow_copy_constructible_v
-        = is_nothrow_copy_constructible<T>::value;                       // C++17
-      template <class T> inline constexpr bool is_nothrow_move_constructible_v
-        = is_nothrow_move_constructible<T>::value;                       // C++17
-      template <class T, class U> inline constexpr bool is_nothrow_assignable_v
-        = is_nothrow_assignable<T, U>::value;                            // C++17
-      template <class T> inline constexpr bool is_nothrow_copy_assignable_v
-        = is_nothrow_copy_assignable<T>::value;                          // C++17
-      template <class T> inline constexpr bool is_nothrow_move_assignable_v
-        = is_nothrow_move_assignable<T>::value;                          // C++17
-      template <class T, class U> inline constexpr bool is_nothrow_swappable_with_v
-        = is_nothrow_swappable_with<T, U>::value;                       // C++17
-      template <class T> inline constexpr bool is_nothrow_swappable_v
-        = is_nothrow_swappable<T>::value;                               // C++17
-      template <class T> inline constexpr bool is_nothrow_destructible_v
-        = is_nothrow_destructible<T>::value;                             // C++17
-      template <class T> inline constexpr bool has_virtual_destructor_v
-        = has_virtual_destructor<T>::value;                              // C++17
-      template<class T> inline constexpr bool has_unique_object_representations_v // C++17
-        = has_unique_object_representations<T>::value;
-
-      // See C++14 20.10.5, type property queries
-      template <class T> inline constexpr size_t alignment_of_v
-        = alignment_of<T>::value;                                        // C++17
-      template <class T> inline constexpr size_t rank_v
-        = rank<T>::value;                                                // C++17
-      template <class T, unsigned I = 0> inline constexpr size_t extent_v
-        = extent<T, I>::value;                                           // C++17
-
-      // See C++14 20.10.6, type relations
-      template <class T, class U> inline constexpr bool is_same_v
-        = is_same<T, U>::value;                                          // C++17
-      template <class Base, class Derived> inline constexpr bool is_base_of_v
-        = is_base_of<Base, Derived>::value;                              // C++17
-      template <class From, class To> inline constexpr bool is_convertible_v
-        = is_convertible<From, To>::value;                               // C++17
-      template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v
-        = is_invocable<Fn, ArgTypes...>::value;                          // C++17
-      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v
-        = is_invocable_r<R, Fn, ArgTypes...>::value;                     // C++17
-      template <class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v
-        = is_nothrow_invocable<Fn, ArgTypes...>::value;                  // C++17
-      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v
-        = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value;             // C++17
-
-      // [meta.logical], logical operator traits:
-      template<class... B> struct conjunction;                           // C++17
-      template<class... B>
-        inline constexpr bool conjunction_v = conjunction<B...>::value;  // C++17
-      template<class... B> struct disjunction;                           // C++17
-      template<class... B>
-        inline constexpr bool disjunction_v = disjunction<B...>::value;  // C++17
-      template<class B> struct negation;                                 // C++17
-      template<class B>
-        inline constexpr bool negation_v = negation<B>::value;           // C++17
+// Synopsis avaiable at http://wg21.link/meta.type.synop.
 
-}
-
-*/
 #include <__config>
 #include <cstddef>
 #include <version>
diff --git a/libcxx/include/typeindex b/libcxx/include/typeindex
--- a/libcxx/include/typeindex
+++ b/libcxx/include/typeindex
@@ -10,39 +10,7 @@
 #ifndef _LIBCPP_TYPEINDEX
 #define _LIBCPP_TYPEINDEX
 
-/*
-
-    typeindex synopsis
-
-namespace std
-{
-
-class type_index
-{
-public:
-    type_index(const type_info& rhs) noexcept;
-
-    bool operator==(const type_index& rhs) const noexcept;
-    bool operator!=(const type_index& rhs) const noexcept;
-    bool operator< (const type_index& rhs) const noexcept;
-    bool operator<=(const type_index& rhs) const noexcept;
-    bool operator> (const type_index& rhs) const noexcept;
-    bool operator>=(const type_index& rhs) const noexcept;
-
-    size_t hash_code() const noexcept;
-    const char* name() const noexcept;
-};
-
-template <>
-struct hash<type_index>
-    : public unary_function<type_index, size_t>
-{
-    size_t operator()(type_index index) const noexcept;
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/type.index.synopsis.
 
 #include <__config>
 #include <__functional_base>
diff --git a/libcxx/include/typeinfo b/libcxx/include/typeinfo
--- a/libcxx/include/typeinfo
+++ b/libcxx/include/typeinfo
@@ -10,51 +10,7 @@
 #ifndef __LIBCPP_TYPEINFO
 #define __LIBCPP_TYPEINFO
 
-/*
-
-    typeinfo synopsis
-
-namespace std {
-
-class type_info
-{
-public:
-    virtual ~type_info();
-
-    bool operator==(const type_info& rhs) const noexcept;
-    bool operator!=(const type_info& rhs) const noexcept;
-
-    bool before(const type_info& rhs) const noexcept;
-    size_t hash_code() const noexcept;
-    const char* name() const noexcept;
-
-    type_info(const type_info& rhs) = delete;
-    type_info& operator=(const type_info& rhs) = delete;
-};
-
-class bad_cast
-    : public exception
-{
-public:
-    bad_cast() noexcept;
-    bad_cast(const bad_cast&) noexcept;
-    bad_cast& operator=(const bad_cast&) noexcept;
-    virtual const char* what() const noexcept;
-};
-
-class bad_typeid
-    : public exception
-{
-public:
-    bad_typeid() noexcept;
-    bad_typeid(const bad_typeid&) noexcept;
-    bad_typeid& operator=(const bad_typeid&) noexcept;
-    virtual const char* what() const noexcept;
-};
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/typeinfo.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/unordered_map b/libcxx/include/unordered_map
--- a/libcxx/include/unordered_map
+++ b/libcxx/include/unordered_map
@@ -10,426 +10,7 @@
 #ifndef _LIBCPP_UNORDERED_MAP
 #define _LIBCPP_UNORDERED_MAP
 
-/*
-
-    unordered_map synopsis
-
-#include <initializer_list>
-
-namespace std
-{
-
-template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
-          class Alloc = allocator<pair<const Key, T>>>
-class unordered_map
-{
-public:
-    // types
-    typedef Key                                                        key_type;
-    typedef T                                                          mapped_type;
-    typedef Hash                                                       hasher;
-    typedef Pred                                                       key_equal;
-    typedef Alloc                                                      allocator_type;
-    typedef pair<const key_type, mapped_type>                          value_type;
-    typedef value_type&                                                reference;
-    typedef const value_type&                                          const_reference;
-    typedef typename allocator_traits<allocator_type>::pointer         pointer;
-    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
-    typedef typename allocator_traits<allocator_type>::size_type       size_type;
-    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
-
-    typedef /unspecified/ iterator;
-    typedef /unspecified/ const_iterator;
-    typedef /unspecified/ local_iterator;
-    typedef /unspecified/ const_local_iterator;
-
-    typedef unspecified                             node_type;            // C++17
-    typedef INSERT_RETURN_TYPE<iterator, node_type> insert_return_type;   // C++17
-
-    unordered_map()
-        noexcept(
-            is_nothrow_default_constructible<hasher>::value &&
-            is_nothrow_default_constructible<key_equal>::value &&
-            is_nothrow_default_constructible<allocator_type>::value);
-    explicit unordered_map(size_type n, const hasher& hf = hasher(),
-                           const key_equal& eql = key_equal(),
-                           const allocator_type& a = allocator_type());
-    template <class InputIterator>
-        unordered_map(InputIterator f, InputIterator l,
-                      size_type n = 0, const hasher& hf = hasher(),
-                      const key_equal& eql = key_equal(),
-                      const allocator_type& a = allocator_type());
-    explicit unordered_map(const allocator_type&);
-    unordered_map(const unordered_map&);
-    unordered_map(const unordered_map&, const Allocator&);
-    unordered_map(unordered_map&&)
-        noexcept(
-            is_nothrow_move_constructible<hasher>::value &&
-            is_nothrow_move_constructible<key_equal>::value &&
-            is_nothrow_move_constructible<allocator_type>::value);
-    unordered_map(unordered_map&&, const Allocator&);
-    unordered_map(initializer_list<value_type>, size_type n = 0,
-                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
-                  const allocator_type& a = allocator_type());
-    unordered_map(size_type n, const allocator_type& a)
-      : unordered_map(n, hasher(), key_equal(), a) {}  // C++14
-    unordered_map(size_type n, const hasher& hf, const allocator_type& a)
-      : unordered_map(n, hf, key_equal(), a) {}  // C++14
-    template <class InputIterator>
-      unordered_map(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
-      : unordered_map(f, l, n, hasher(), key_equal(), a) {}  // C++14
-    template <class InputIterator>
-      unordered_map(InputIterator f, InputIterator l, size_type n, const hasher& hf,
-        const allocator_type& a)
-      : unordered_map(f, l, n, hf, key_equal(), a) {}  // C++14
-    unordered_map(initializer_list<value_type> il, size_type n, const allocator_type& a)
-      : unordered_map(il, n, hasher(), key_equal(), a) {}  // C++14
-    unordered_map(initializer_list<value_type> il, size_type n, const hasher& hf,
-      const allocator_type& a)
-      : unordered_map(il, n, hf, key_equal(), a) {}  // C++14
-    ~unordered_map();
-    unordered_map& operator=(const unordered_map&);
-    unordered_map& operator=(unordered_map&&)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<hasher>::value &&
-            is_nothrow_move_assignable<key_equal>::value);
-    unordered_map& operator=(initializer_list<value_type>);
-
-    allocator_type get_allocator() const noexcept;
-
-    bool      empty() const noexcept;
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-
-    iterator       begin() noexcept;
-    iterator       end() noexcept;
-    const_iterator begin()  const noexcept;
-    const_iterator end()    const noexcept;
-    const_iterator cbegin() const noexcept;
-    const_iterator cend()   const noexcept;
-
-    template <class... Args>
-        pair<iterator, bool> emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    pair<iterator, bool> insert(const value_type& obj);
-    template <class P>
-        pair<iterator, bool> insert(P&& obj);
-    iterator insert(const_iterator hint, const value_type& obj);
-    template <class P>
-        iterator insert(const_iterator hint, P&& obj);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type>);
-
-    node_type extract(const_iterator position);                                       // C++17
-    node_type extract(const key_type& x);                                             // C++17
-    insert_return_type insert(node_type&& nh);                                        // C++17
-    iterator           insert(const_iterator hint, node_type&& nh);                   // C++17
-
-    template <class... Args>
-        pair<iterator, bool> try_emplace(const key_type& k, Args&&... args);          // C++17
-    template <class... Args>
-        pair<iterator, bool> try_emplace(key_type&& k, Args&&... args);               // C++17
-    template <class... Args>
-        iterator try_emplace(const_iterator hint, const key_type& k, Args&&... args); // C++17
-    template <class... Args>
-        iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args);      // C++17
-    template <class M>
-        pair<iterator, bool> insert_or_assign(const key_type& k, M&& obj);            // C++17
-    template <class M>
-        pair<iterator, bool> insert_or_assign(key_type&& k, M&& obj);                 // C++17
-    template <class M>
-        iterator insert_or_assign(const_iterator hint, const key_type& k, M&& obj);   // C++17
-    template <class M>
-        iterator insert_or_assign(const_iterator hint, key_type&& k, M&& obj);        // C++17
-
-    iterator erase(const_iterator position);
-    iterator erase(iterator position);  // C++14
-    size_type erase(const key_type& k);
-    iterator erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class H2, class P2>
-      void merge(unordered_map<Key, T, H2, P2, Allocator>& source);         // C++17
-    template<class H2, class P2>
-      void merge(unordered_map<Key, T, H2, P2, Allocator>&& source);        // C++17
-    template<class H2, class P2>
-      void merge(unordered_multimap<Key, T, H2, P2, Allocator>& source);    // C++17
-    template<class H2, class P2>
-      void merge(unordered_multimap<Key, T, H2, P2, Allocator>&& source);   // C++17
-
-    void swap(unordered_map&)
-        noexcept(
-            (!allocator_type::propagate_on_container_swap::value ||
-             __is_nothrow_swappable<allocator_type>::value) &&
-            __is_nothrow_swappable<hasher>::value &&
-            __is_nothrow_swappable<key_equal>::value);
-
-    hasher hash_function() const;
-    key_equal key_eq() const;
-
-    iterator       find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);              // C++20
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++20
-    size_type count(const key_type& k) const;
-    template<typename K>
-        size_type count(const K& k) const; // C++20
-    bool contains(const key_type& k) const; // C++20
-    template<typename K>
-        bool contains(const K& k) const; // C++20
-    pair<iterator, iterator>             equal_range(const key_type& k);
-    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator, iterator>             equal_range(const K& k); // C++20
-    template<typename K>
-        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
-
-    mapped_type& operator[](const key_type& k);
-    mapped_type& operator[](key_type&& k);
-
-    mapped_type&       at(const key_type& k);
-    const mapped_type& at(const key_type& k) const;
-
-    size_type bucket_count() const noexcept;
-    size_type max_bucket_count() const noexcept;
-
-    size_type bucket_size(size_type n) const;
-    size_type bucket(const key_type& k) const;
-
-    local_iterator       begin(size_type n);
-    local_iterator       end(size_type n);
-    const_local_iterator begin(size_type n) const;
-    const_local_iterator end(size_type n) const;
-    const_local_iterator cbegin(size_type n) const;
-    const_local_iterator cend(size_type n) const;
-
-    float load_factor() const noexcept;
-    float max_load_factor() const noexcept;
-    void max_load_factor(float z);
-    void rehash(size_type n);
-    void reserve(size_type n);
-};
-
-template <class Key, class T, class Hash, class Pred, class Alloc>
-    void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x,
-              unordered_map<Key, T, Hash, Pred, Alloc>& y)
-              noexcept(noexcept(x.swap(y)));
-
-template <class Key, class T, class Hash, class Pred, class Alloc>
-    bool
-    operator==(const unordered_map<Key, T, Hash, Pred, Alloc>& x,
-               const unordered_map<Key, T, Hash, Pred, Alloc>& y);
-
-template <class Key, class T, class Hash, class Pred, class Alloc>
-    bool
-    operator!=(const unordered_map<Key, T, Hash, Pred, Alloc>& x,
-               const unordered_map<Key, T, Hash, Pred, Alloc>& y);
-
-template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
-          class Alloc = allocator<pair<const Key, T>>>
-class unordered_multimap
-{
-public:
-    // types
-    typedef Key                                                        key_type;
-    typedef T                                                          mapped_type;
-    typedef Hash                                                       hasher;
-    typedef Pred                                                       key_equal;
-    typedef Alloc                                                      allocator_type;
-    typedef pair<const key_type, mapped_type>                          value_type;
-    typedef value_type&                                                reference;
-    typedef const value_type&                                          const_reference;
-    typedef typename allocator_traits<allocator_type>::pointer         pointer;
-    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
-    typedef typename allocator_traits<allocator_type>::size_type       size_type;
-    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
-
-    typedef /unspecified/ iterator;
-    typedef /unspecified/ const_iterator;
-    typedef /unspecified/ local_iterator;
-    typedef /unspecified/ const_local_iterator;
-
-    typedef unspecified node_type;    // C++17
-
-    unordered_multimap()
-        noexcept(
-            is_nothrow_default_constructible<hasher>::value &&
-            is_nothrow_default_constructible<key_equal>::value &&
-            is_nothrow_default_constructible<allocator_type>::value);
-    explicit unordered_multimap(size_type n, const hasher& hf = hasher(),
-                           const key_equal& eql = key_equal(),
-                           const allocator_type& a = allocator_type());
-    template <class InputIterator>
-        unordered_multimap(InputIterator f, InputIterator l,
-                      size_type n = 0, const hasher& hf = hasher(),
-                      const key_equal& eql = key_equal(),
-                      const allocator_type& a = allocator_type());
-    explicit unordered_multimap(const allocator_type&);
-    unordered_multimap(const unordered_multimap&);
-    unordered_multimap(const unordered_multimap&, const Allocator&);
-    unordered_multimap(unordered_multimap&&)
-        noexcept(
-            is_nothrow_move_constructible<hasher>::value &&
-            is_nothrow_move_constructible<key_equal>::value &&
-            is_nothrow_move_constructible<allocator_type>::value);
-    unordered_multimap(unordered_multimap&&, const Allocator&);
-    unordered_multimap(initializer_list<value_type>, size_type n = 0,
-                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
-                  const allocator_type& a = allocator_type());
-    unordered_multimap(size_type n, const allocator_type& a)
-      : unordered_multimap(n, hasher(), key_equal(), a) {}  // C++14
-    unordered_multimap(size_type n, const hasher& hf, const allocator_type& a)
-      : unordered_multimap(n, hf, key_equal(), a) {}  // C++14
-    template <class InputIterator>
-      unordered_multimap(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
-      : unordered_multimap(f, l, n, hasher(), key_equal(), a) {}  // C++14
-    template <class InputIterator>
-      unordered_multimap(InputIterator f, InputIterator l, size_type n, const hasher& hf,
-        const allocator_type& a)
-      : unordered_multimap(f, l, n, hf, key_equal(), a) {}  // C++14
-    unordered_multimap(initializer_list<value_type> il, size_type n, const allocator_type& a)
-      : unordered_multimap(il, n, hasher(), key_equal(), a) {}  // C++14
-    unordered_multimap(initializer_list<value_type> il, size_type n, const hasher& hf,
-      const allocator_type& a)
-      : unordered_multimap(il, n, hf, key_equal(), a) {}  // C++14
-    ~unordered_multimap();
-    unordered_multimap& operator=(const unordered_multimap&);
-    unordered_multimap& operator=(unordered_multimap&&)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<hasher>::value &&
-            is_nothrow_move_assignable<key_equal>::value);
-    unordered_multimap& operator=(initializer_list<value_type>);
-
-    allocator_type get_allocator() const noexcept;
-
-    bool      empty() const noexcept;
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-
-    iterator       begin() noexcept;
-    iterator       end() noexcept;
-    const_iterator begin()  const noexcept;
-    const_iterator end()    const noexcept;
-    const_iterator cbegin() const noexcept;
-    const_iterator cend()   const noexcept;
-
-    template <class... Args>
-        iterator emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    iterator insert(const value_type& obj);
-    template <class P>
-        iterator insert(P&& obj);
-    iterator insert(const_iterator hint, const value_type& obj);
-    template <class P>
-        iterator insert(const_iterator hint, P&& obj);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type>);
-
-    node_type extract(const_iterator position);                // C++17
-    node_type extract(const key_type& x);                      // C++17
-    iterator insert(node_type&& nh);                           // C++17
-    iterator insert(const_iterator hint, node_type&& nh);      // C++17
-
-    iterator erase(const_iterator position);
-    iterator erase(iterator position);  // C++14
-    size_type erase(const key_type& k);
-    iterator erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class H2, class P2>
-      void merge(unordered_multimap<Key, T, H2, P2, Allocator>& source);    // C++17
-    template<class H2, class P2>
-      void merge(unordered_multimap<Key, T, H2, P2, Allocator>&& source);   // C++17
-    template<class H2, class P2>
-      void merge(unordered_map<Key, T, H2, P2, Allocator>& source);         // C++17
-    template<class H2, class P2>
-      void merge(unordered_map<Key, T, H2, P2, Allocator>&& source);        // C++17
-
-    void swap(unordered_multimap&)
-        noexcept(
-            (!allocator_type::propagate_on_container_swap::value ||
-             __is_nothrow_swappable<allocator_type>::value) &&
-            __is_nothrow_swappable<hasher>::value &&
-            __is_nothrow_swappable<key_equal>::value);
-
-    hasher hash_function() const;
-    key_equal key_eq() const;
-
-    iterator       find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);              // C++20
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++20
-    size_type count(const key_type& k) const;
-    template<typename K>
-        size_type count(const K& k) const; // C++20
-    bool contains(const key_type& k) const; // C++20
-    template<typename K>
-        bool contains(const K& k) const; // C++20
-    pair<iterator, iterator>             equal_range(const key_type& k);
-    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator, iterator>             equal_range(const K& k); // C++20
-    template<typename K>
-        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
-
-    size_type bucket_count() const noexcept;
-    size_type max_bucket_count() const noexcept;
-
-    size_type bucket_size(size_type n) const;
-    size_type bucket(const key_type& k) const;
-
-    local_iterator       begin(size_type n);
-    local_iterator       end(size_type n);
-    const_local_iterator begin(size_type n) const;
-    const_local_iterator end(size_type n) const;
-    const_local_iterator cbegin(size_type n) const;
-    const_local_iterator cend(size_type n) const;
-
-    float load_factor() const noexcept;
-    float max_load_factor() const noexcept;
-    void max_load_factor(float z);
-    void rehash(size_type n);
-    void reserve(size_type n);
-};
-
-template <class Key, class T, class Hash, class Pred, class Alloc>
-    void swap(unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
-              unordered_multimap<Key, T, Hash, Pred, Alloc>& y)
-              noexcept(noexcept(x.swap(y)));
-
-template <class K, class T, class H, class P, class A, class Predicate>
-    typename unordered_map<K, T, H, P, A>::size_type
-    erase_if(unordered_map<K, T, H, P, A>& c, Predicate pred);       // C++20
-
-template <class K, class T, class H, class P, class A, class Predicate>
-    typename unordered_multimap<K, T, H, P, A>::size_type
-    erase_if(unordered_multimap<K, T, H, P, A>& c, Predicate pred);  // C++20
-
-template <class Key, class T, class Hash, class Pred, class Alloc>
-    bool
-    operator==(const unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
-               const unordered_multimap<Key, T, Hash, Pred, Alloc>& y);
-
-template <class Key, class T, class Hash, class Pred, class Alloc>
-    bool
-    operator!=(const unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
-               const unordered_multimap<Key, T, Hash, Pred, Alloc>& y);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/unord.map.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/unordered_set b/libcxx/include/unordered_set
--- a/libcxx/include/unordered_set
+++ b/libcxx/include/unordered_set
@@ -10,381 +10,7 @@
 #ifndef _LIBCPP_UNORDERED_SET
 #define _LIBCPP_UNORDERED_SET
 
-/*
-
-    unordered_set synopsis
-
-#include <initializer_list>
-
-namespace std
-{
-
-template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
-          class Alloc = allocator<Value>>
-class unordered_set
-{
-public:
-    // types
-    typedef Value                                                      key_type;
-    typedef key_type                                                   value_type;
-    typedef Hash                                                       hasher;
-    typedef Pred                                                       key_equal;
-    typedef Alloc                                                      allocator_type;
-    typedef value_type&                                                reference;
-    typedef const value_type&                                          const_reference;
-    typedef typename allocator_traits<allocator_type>::pointer         pointer;
-    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
-    typedef typename allocator_traits<allocator_type>::size_type       size_type;
-    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
-
-    typedef /unspecified/ iterator;
-    typedef /unspecified/ const_iterator;
-    typedef /unspecified/ local_iterator;
-    typedef /unspecified/ const_local_iterator;
-
-    typedef unspecified node_type unspecified;                            // C++17
-    typedef INSERT_RETURN_TYPE<iterator, node_type> insert_return_type;   // C++17
-
-    unordered_set()
-        noexcept(
-            is_nothrow_default_constructible<hasher>::value &&
-            is_nothrow_default_constructible<key_equal>::value &&
-            is_nothrow_default_constructible<allocator_type>::value);
-    explicit unordered_set(size_type n, const hasher& hf = hasher(),
-                           const key_equal& eql = key_equal(),
-                           const allocator_type& a = allocator_type());
-    template <class InputIterator>
-        unordered_set(InputIterator f, InputIterator l,
-                      size_type n = 0, const hasher& hf = hasher(),
-                      const key_equal& eql = key_equal(),
-                      const allocator_type& a = allocator_type());
-    explicit unordered_set(const allocator_type&);
-    unordered_set(const unordered_set&);
-    unordered_set(const unordered_set&, const Allocator&);
-    unordered_set(unordered_set&&)
-        noexcept(
-            is_nothrow_move_constructible<hasher>::value &&
-            is_nothrow_move_constructible<key_equal>::value &&
-            is_nothrow_move_constructible<allocator_type>::value);
-    unordered_set(unordered_set&&, const Allocator&);
-    unordered_set(initializer_list<value_type>, size_type n = 0,
-                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
-                  const allocator_type& a = allocator_type());
-    unordered_set(size_type n, const allocator_type& a); // C++14
-    unordered_set(size_type n, const hasher& hf, const allocator_type& a); // C++14
-    template <class InputIterator>
-      unordered_set(InputIterator f, InputIterator l, size_type n, const allocator_type& a); // C++14
-    template <class InputIterator>
-      unordered_set(InputIterator f, InputIterator l, size_type n,
-                    const hasher& hf,  const allocator_type& a); // C++14
-    unordered_set(initializer_list<value_type> il, size_type n, const allocator_type& a); // C++14
-    unordered_set(initializer_list<value_type> il, size_type n,
-                  const hasher& hf,  const allocator_type& a); // C++14
-    ~unordered_set();
-    unordered_set& operator=(const unordered_set&);
-    unordered_set& operator=(unordered_set&&)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<hasher>::value &&
-            is_nothrow_move_assignable<key_equal>::value);
-    unordered_set& operator=(initializer_list<value_type>);
-
-    allocator_type get_allocator() const noexcept;
-
-    bool      empty() const noexcept;
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-
-    iterator       begin() noexcept;
-    iterator       end() noexcept;
-    const_iterator begin()  const noexcept;
-    const_iterator end()    const noexcept;
-    const_iterator cbegin() const noexcept;
-    const_iterator cend()   const noexcept;
-
-    template <class... Args>
-        pair<iterator, bool> emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    pair<iterator, bool> insert(const value_type& obj);
-    pair<iterator, bool> insert(value_type&& obj);
-    iterator insert(const_iterator hint, const value_type& obj);
-    iterator insert(const_iterator hint, value_type&& obj);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type>);
-
-    node_type extract(const_iterator position);                       // C++17
-    node_type extract(const key_type& x);                             // C++17
-    insert_return_type insert(node_type&& nh);                        // C++17
-    iterator           insert(const_iterator hint, node_type&& nh);   // C++17
-
-    iterator erase(const_iterator position);
-    iterator erase(iterator position);  // C++14
-    size_type erase(const key_type& k);
-    iterator erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class H2, class P2>
-      void merge(unordered_set<Key, H2, P2, Allocator>& source);         // C++17
-    template<class H2, class P2>
-      void merge(unordered_set<Key, H2, P2, Allocator>&& source);        // C++17
-    template<class H2, class P2>
-      void merge(unordered_multiset<Key, H2, P2, Allocator>& source);    // C++17
-    template<class H2, class P2>
-      void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);   // C++17
-
-    void swap(unordered_set&)
-       noexcept(allocator_traits<Allocator>::is_always_equal::value &&
-                 noexcept(swap(declval<hasher&>(), declval<hasher&>())) &&
-                 noexcept(swap(declval<key_equal&>(), declval<key_equal&>()))); // C++17
-
-    hasher hash_function() const;
-    key_equal key_eq() const;
-
-    iterator       find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);              // C++20
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++20
-    size_type count(const key_type& k) const;
-    template<typename K>
-        size_type count(const K& k) const; // C++20
-    bool contains(const key_type& k) const; // C++20
-    template<typename K>
-        bool contains(const K& k) const; // C++20
-    pair<iterator, iterator>             equal_range(const key_type& k);
-    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator, iterator>             equal_range(const K& k); // C++20
-    template<typename K>
-        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
-
-    size_type bucket_count() const noexcept;
-    size_type max_bucket_count() const noexcept;
-
-    size_type bucket_size(size_type n) const;
-    size_type bucket(const key_type& k) const;
-
-    local_iterator       begin(size_type n);
-    local_iterator       end(size_type n);
-    const_local_iterator begin(size_type n) const;
-    const_local_iterator end(size_type n) const;
-    const_local_iterator cbegin(size_type n) const;
-    const_local_iterator cend(size_type n) const;
-
-    float load_factor() const noexcept;
-    float max_load_factor() const noexcept;
-    void max_load_factor(float z);
-    void rehash(size_type n);
-    void reserve(size_type n);
-};
-
-template <class Value, class Hash, class Pred, class Alloc>
-    void swap(unordered_set<Value, Hash, Pred, Alloc>& x,
-              unordered_set<Value, Hash, Pred, Alloc>& y)
-              noexcept(noexcept(x.swap(y)));
-
-template <class Value, class Hash, class Pred, class Alloc>
-    bool
-    operator==(const unordered_set<Value, Hash, Pred, Alloc>& x,
-               const unordered_set<Value, Hash, Pred, Alloc>& y);
-
-template <class Value, class Hash, class Pred, class Alloc>
-    bool
-    operator!=(const unordered_set<Value, Hash, Pred, Alloc>& x,
-               const unordered_set<Value, Hash, Pred, Alloc>& y);
-
-template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
-          class Alloc = allocator<Value>>
-class unordered_multiset
-{
-public:
-    // types
-    typedef Value                                                      key_type;
-    typedef key_type                                                   value_type;
-    typedef Hash                                                       hasher;
-    typedef Pred                                                       key_equal;
-    typedef Alloc                                                      allocator_type;
-    typedef value_type&                                                reference;
-    typedef const value_type&                                          const_reference;
-    typedef typename allocator_traits<allocator_type>::pointer         pointer;
-    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
-    typedef typename allocator_traits<allocator_type>::size_type       size_type;
-    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
-
-    typedef /unspecified/ iterator;
-    typedef /unspecified/ const_iterator;
-    typedef /unspecified/ local_iterator;
-    typedef /unspecified/ const_local_iterator;
-
-    typedef unspecified node_type unspecified;   // C++17
-
-    unordered_multiset()
-        noexcept(
-            is_nothrow_default_constructible<hasher>::value &&
-            is_nothrow_default_constructible<key_equal>::value &&
-            is_nothrow_default_constructible<allocator_type>::value);
-    explicit unordered_multiset(size_type n, const hasher& hf = hasher(),
-                           const key_equal& eql = key_equal(),
-                           const allocator_type& a = allocator_type());
-    template <class InputIterator>
-        unordered_multiset(InputIterator f, InputIterator l,
-                      size_type n = 0, const hasher& hf = hasher(),
-                      const key_equal& eql = key_equal(),
-                      const allocator_type& a = allocator_type());
-    explicit unordered_multiset(const allocator_type&);
-    unordered_multiset(const unordered_multiset&);
-    unordered_multiset(const unordered_multiset&, const Allocator&);
-    unordered_multiset(unordered_multiset&&)
-        noexcept(
-            is_nothrow_move_constructible<hasher>::value &&
-            is_nothrow_move_constructible<key_equal>::value &&
-            is_nothrow_move_constructible<allocator_type>::value);
-    unordered_multiset(unordered_multiset&&, const Allocator&);
-    unordered_multiset(initializer_list<value_type>, size_type n = /see below/,
-                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
-                  const allocator_type& a = allocator_type());
-    unordered_multiset(size_type n, const allocator_type& a); // C++14
-    unordered_multiset(size_type n, const hasher& hf, const allocator_type& a); // C++14
-    template <class InputIterator>
-      unordered_multiset(InputIterator f, InputIterator l, size_type n, const allocator_type& a); // C++14
-    template <class InputIterator>
-      unordered_multiset(InputIterator f, InputIterator l, size_type n,
-                         const hasher& hf, const allocator_type& a); // C++14
-    unordered_multiset(initializer_list<value_type> il, size_type n, const allocator_type& a); // C++14
-    unordered_multiset(initializer_list<value_type> il, size_type n,
-                       const hasher& hf,  const allocator_type& a); // C++14
-    ~unordered_multiset();
-    unordered_multiset& operator=(const unordered_multiset&);
-    unordered_multiset& operator=(unordered_multiset&&)
-        noexcept(
-            allocator_type::propagate_on_container_move_assignment::value &&
-            is_nothrow_move_assignable<allocator_type>::value &&
-            is_nothrow_move_assignable<hasher>::value &&
-            is_nothrow_move_assignable<key_equal>::value);
-    unordered_multiset& operator=(initializer_list<value_type>);
-
-    allocator_type get_allocator() const noexcept;
-
-    bool      empty() const noexcept;
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-
-    iterator       begin() noexcept;
-    iterator       end() noexcept;
-    const_iterator begin()  const noexcept;
-    const_iterator end()    const noexcept;
-    const_iterator cbegin() const noexcept;
-    const_iterator cend()   const noexcept;
-
-    template <class... Args>
-        iterator emplace(Args&&... args);
-    template <class... Args>
-        iterator emplace_hint(const_iterator position, Args&&... args);
-    iterator insert(const value_type& obj);
-    iterator insert(value_type&& obj);
-    iterator insert(const_iterator hint, const value_type& obj);
-    iterator insert(const_iterator hint, value_type&& obj);
-    template <class InputIterator>
-        void insert(InputIterator first, InputIterator last);
-    void insert(initializer_list<value_type>);
-
-    node_type extract(const_iterator position);             // C++17
-    node_type extract(const key_type& x);                   // C++17
-    iterator insert(node_type&& nh);                        // C++17
-    iterator insert(const_iterator hint, node_type&& nh);   // C++17
-
-    iterator erase(const_iterator position);
-    iterator erase(iterator position);  // C++14
-    size_type erase(const key_type& k);
-    iterator erase(const_iterator first, const_iterator last);
-    void clear() noexcept;
-
-    template<class H2, class P2>
-      void merge(unordered_multiset<Key, H2, P2, Allocator>& source);    // C++17
-    template<class H2, class P2>
-      void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);   // C++17
-    template<class H2, class P2>
-      void merge(unordered_set<Key, H2, P2, Allocator>& source);         // C++17
-    template<class H2, class P2>
-      void merge(unordered_set<Key, H2, P2, Allocator>&& source);        // C++17
-
-    void swap(unordered_multiset&)
-       noexcept(allocator_traits<Allocator>::is_always_equal::value &&
-                 noexcept(swap(declval<hasher&>(), declval<hasher&>())) &&
-                 noexcept(swap(declval<key_equal&>(), declval<key_equal&>()))); // C++17
-
-    hasher hash_function() const;
-    key_equal key_eq() const;
-
-    iterator       find(const key_type& k);
-    const_iterator find(const key_type& k) const;
-    template<typename K>
-        iterator find(const K& x);              // C++20
-    template<typename K>
-        const_iterator find(const K& x) const;  // C++20
-    size_type count(const key_type& k) const;
-    template<typename K>
-        size_type count(const K& k) const; // C++20
-    bool contains(const key_type& k) const; // C++20
-    template<typename K>
-        bool contains(const K& k) const; // C++20
-    pair<iterator, iterator>             equal_range(const key_type& k);
-    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
-    template<typename K>
-        pair<iterator, iterator>             equal_range(const K& k); // C++20
-    template<typename K>
-        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
-
-    size_type bucket_count() const noexcept;
-    size_type max_bucket_count() const noexcept;
-
-    size_type bucket_size(size_type n) const;
-    size_type bucket(const key_type& k) const;
-
-    local_iterator       begin(size_type n);
-    local_iterator       end(size_type n);
-    const_local_iterator begin(size_type n) const;
-    const_local_iterator end(size_type n) const;
-    const_local_iterator cbegin(size_type n) const;
-    const_local_iterator cend(size_type n) const;
-
-    float load_factor() const noexcept;
-    float max_load_factor() const noexcept;
-    void max_load_factor(float z);
-    void rehash(size_type n);
-    void reserve(size_type n);
-};
-
-template <class Value, class Hash, class Pred, class Alloc>
-    void swap(unordered_multiset<Value, Hash, Pred, Alloc>& x,
-              unordered_multiset<Value, Hash, Pred, Alloc>& y)
-              noexcept(noexcept(x.swap(y)));
-
-template <class K, class T, class H, class P, class A, class Predicate>
-    typename unordered_set<K, T, H, P, A>::size_type
-    erase_if(unordered_set<K, T, H, P, A>& c, Predicate pred);       // C++20
-
-template <class K, class T, class H, class P, class A, class Predicate>
-    typename unordered_multiset<K, T, H, P, A>::size_type
-    erase_if(unordered_multiset<K, T, H, P, A>& c, Predicate pred);  // C++20
-
-
-template <class Value, class Hash, class Pred, class Alloc>
-    bool
-    operator==(const unordered_multiset<Value, Hash, Pred, Alloc>& x,
-               const unordered_multiset<Value, Hash, Pred, Alloc>& y);
-
-template <class Value, class Hash, class Pred, class Alloc>
-    bool
-    operator!=(const unordered_multiset<Value, Hash, Pred, Alloc>& x,
-               const unordered_multiset<Value, Hash, Pred, Alloc>& y);
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/unord.set.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/utility b/libcxx/include/utility
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -10,202 +10,7 @@
 #ifndef _LIBCPP_UTILITY
 #define _LIBCPP_UTILITY
 
-/*
-    utility synopsis
-
-#include <initializer_list>
-
-namespace std
-{
-
-template <class T>
-    void
-    swap(T& a, T& b);
-
-namespace rel_ops
-{
-    template<class T> bool operator!=(const T&, const T&);
-    template<class T> bool operator> (const T&, const T&);
-    template<class T> bool operator<=(const T&, const T&);
-    template<class T> bool operator>=(const T&, const T&);
-}
-
-template<class T>
-void
-swap(T& a, T& b) noexcept(is_nothrow_move_constructible<T>::value &&
-                          is_nothrow_move_assignable<T>::value);
-
-template <class T, size_t N>
-void
-swap(T (&a)[N], T (&b)[N]) noexcept(noexcept(swap(*a, *b)));
-
-template <class T> T&& forward(typename remove_reference<T>::type& t) noexcept;  // constexpr in C++14
-template <class T> T&& forward(typename remove_reference<T>::type&& t) noexcept; // constexpr in C++14
-
-template <class T> typename remove_reference<T>::type&& move(T&&) noexcept;      // constexpr in C++14
-
-template <class T>
-    typename conditional
-    <
-        !is_nothrow_move_constructible<T>::value && is_copy_constructible<T>::value,
-        const T&,
-        T&&
-    >::type
-    move_if_noexcept(T& x) noexcept; // constexpr in C++14
-
-template <class T> constexpr add_const_t<T>& as_const(T& t) noexcept;      // C++17
-template <class T>                      void as_const(const T&&) = delete; // C++17
-
-template <class T> typename add_rvalue_reference<T>::type declval() noexcept;
-
-template<class T, class U> constexpr bool cmp_equal(T t, U u) noexcept;         // C++20
-template<class T, class U> constexpr bool cmp_not_equal(T t, U u) noexcept;     // C++20
-template<class T, class U> constexpr bool cmp_less(T t, U u) noexcept;          // C++20
-template<class T, class U> constexpr bool cmp_greater(T t, U u) noexcept;       // C++20
-template<class T, class U> constexpr bool cmp_less_equal(T t, U u) noexcept;    // C++20
-template<class T, class U> constexpr bool cmp_greater_equal(T t, U u) noexcept; // C++20
-template<class R, class T> constexpr bool in_range(T t) noexcept;               // C++20
-
-template <class T1, class T2>
-struct pair
-{
-    typedef T1 first_type;
-    typedef T2 second_type;
-
-    T1 first;
-    T2 second;
-
-    pair(const pair&) = default;
-    pair(pair&&) = default;
-    explicit(see-below) constexpr pair();
-    explicit(see-below) pair(const T1& x, const T2& y);                          // constexpr in C++14
-    template <class U, class V> explicit(see-below) pair(U&& x, V&& y);          // constexpr in C++14
-    template <class U, class V> explicit(see-below) pair(const pair<U, V>& p);   // constexpr in C++14
-    template <class U, class V> explicit(see-below) pair(pair<U, V>&& p);        // constexpr in C++14
-    template <class... Args1, class... Args2>
-        pair(piecewise_construct_t, tuple<Args1...> first_args,
-             tuple<Args2...> second_args);                                       // constexpr in C++20
-
-    template <class U, class V> pair& operator=(const pair<U, V>& p);            // constexpr in C++20
-    pair& operator=(pair&& p) noexcept(is_nothrow_move_assignable<T1>::value &&
-                                       is_nothrow_move_assignable<T2>::value);   // constexpr in C++20
-    template <class U, class V> pair& operator=(pair<U, V>&& p);                 // constexpr in C++20
-
-    void swap(pair& p) noexcept(is_nothrow_swappable_v<T1> &&
-                                is_nothrow_swappable_v<T2>);                     // constexpr in C++20
-};
-
-template <class T1, class T2> bool operator==(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
-template <class T1, class T2> bool operator!=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
-template <class T1, class T2> bool operator< (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
-template <class T1, class T2> bool operator> (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
-template <class T1, class T2> bool operator>=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
-template <class T1, class T2> bool operator<=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
-
-template <class T1, class T2> pair<V1, V2> make_pair(T1&&, T2&&);                // constexpr in C++14
-template <class T1, class T2>
-void
-swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));            // constexpr in C++20
-
-struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
-inline constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
-
-template <class T> struct tuple_size;
-template <size_t I, class T> struct tuple_element;
-
-template <class T1, class T2> struct tuple_size<pair<T1, T2> >;
-template <class T1, class T2> struct tuple_element<0, pair<T1, T2> >;
-template <class T1, class T2> struct tuple_element<1, pair<T1, T2> >;
-
-template<size_t I, class T1, class T2>
-    typename tuple_element<I, pair<T1, T2> >::type&
-    get(pair<T1, T2>&) noexcept; // constexpr in C++14
-
-template<size_t I, class T1, class T2>
-    const typename tuple_element<I, pair<T1, T2> >::type&
-    get(const pair<T1, T2>&) noexcept; // constexpr in C++14
-
-template<size_t I, class T1, class T2>
-    typename tuple_element<I, pair<T1, T2> >::type&&
-    get(pair<T1, T2>&&) noexcept; // constexpr in C++14
-
-template<size_t I, class T1, class T2>
-    const typename tuple_element<I, pair<T1, T2> >::type&&
-    get(const pair<T1, T2>&&) noexcept; // constexpr in C++14
-
-template<class T1, class T2>
-    constexpr T1& get(pair<T1, T2>&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr const T1& get(const pair<T1, T2>&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr T1&& get(pair<T1, T2>&&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr const T1&& get(const pair<T1, T2>&&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr T1& get(pair<T2, T1>&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr const T1& get(const pair<T2, T1>&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr T1&& get(pair<T2, T1>&&) noexcept; // C++14
-
-template<class T1, class T2>
-    constexpr const T1&& get(const pair<T2, T1>&&) noexcept; // C++14
-
-// C++14
-
-template<class T, T... I>
-struct integer_sequence
-{
-    typedef T value_type;
-
-    static constexpr size_t size() noexcept;
-};
-
-template<size_t... I>
-  using index_sequence = integer_sequence<size_t, I...>;
-
-template<class T, T N>
-  using make_integer_sequence = integer_sequence<T, 0, 1, ..., N-1>;
-template<size_t N>
-  using make_index_sequence = make_integer_sequence<size_t, N>;
-
-template<class... T>
-  using index_sequence_for = make_index_sequence<sizeof...(T)>;
-
-template<class T, class U=T>
-    T exchange(T& obj, U&& new_value);
-
-// 20.2.7, in-place construction // C++17
-struct in_place_t {
-  explicit in_place_t() = default;
-};
-inline constexpr in_place_t in_place{};
-template <class T>
-  struct in_place_type_t {
-    explicit in_place_type_t() = default;
-  };
-template <class T>
-  inline constexpr in_place_type_t<T> in_place_type{};
-template <size_t I>
-  struct in_place_index_t {
-    explicit in_place_index_t() = default;
-  };
-template <size_t I>
-  inline constexpr in_place_index_t<I> in_place_index{};
-
-// [utility.underlying], to_underlying
-template <class T>
-    constexpr underlying_type_t<T> to_underlying( T value ) noexcept; // C++2b
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/utility.syn.
 
 #include <__config>
 #include <__debug>
diff --git a/libcxx/include/valarray b/libcxx/include/valarray
--- a/libcxx/include/valarray
+++ b/libcxx/include/valarray
@@ -10,334 +10,7 @@
 #ifndef _LIBCPP_VALARRAY
 #define _LIBCPP_VALARRAY
 
-/*
-    valarray synopsis
-
-namespace std
-{
-
-template<class T>
-class valarray
-{
-public:
-    typedef T value_type;
-
-    // construct/destroy:
-    valarray();
-    explicit valarray(size_t n);
-    valarray(const value_type& x, size_t n);
-    valarray(const value_type* px, size_t n);
-    valarray(const valarray& v);
-    valarray(valarray&& v) noexcept;
-    valarray(const slice_array<value_type>& sa);
-    valarray(const gslice_array<value_type>& ga);
-    valarray(const mask_array<value_type>& ma);
-    valarray(const indirect_array<value_type>& ia);
-    valarray(initializer_list<value_type> il);
-    ~valarray();
-
-    // assignment:
-    valarray& operator=(const valarray& v);
-    valarray& operator=(valarray&& v) noexcept;
-    valarray& operator=(initializer_list<value_type> il);
-    valarray& operator=(const value_type& x);
-    valarray& operator=(const slice_array<value_type>& sa);
-    valarray& operator=(const gslice_array<value_type>& ga);
-    valarray& operator=(const mask_array<value_type>& ma);
-    valarray& operator=(const indirect_array<value_type>& ia);
-
-    // element access:
-    const value_type& operator[](size_t i) const;
-    value_type&       operator[](size_t i);
-
-    // subset operations:
-    valarray                   operator[](slice s) const;
-    slice_array<value_type>    operator[](slice s);
-    valarray                   operator[](const gslice& gs) const;
-    gslice_array<value_type>   operator[](const gslice& gs);
-    valarray                   operator[](const valarray<bool>& vb) const;
-    mask_array<value_type>     operator[](const valarray<bool>& vb);
-    valarray                   operator[](const valarray<size_t>& vs) const;
-    indirect_array<value_type> operator[](const valarray<size_t>& vs);
-
-    // unary operators:
-    valarray       operator+() const;
-    valarray       operator-() const;
-    valarray       operator~() const;
-    valarray<bool> operator!() const;
-
-    // computed assignment:
-    valarray& operator*= (const value_type& x);
-    valarray& operator/= (const value_type& x);
-    valarray& operator%= (const value_type& x);
-    valarray& operator+= (const value_type& x);
-    valarray& operator-= (const value_type& x);
-    valarray& operator^= (const value_type& x);
-    valarray& operator&= (const value_type& x);
-    valarray& operator|= (const value_type& x);
-    valarray& operator<<=(const value_type& x);
-    valarray& operator>>=(const value_type& x);
-
-    valarray& operator*= (const valarray& v);
-    valarray& operator/= (const valarray& v);
-    valarray& operator%= (const valarray& v);
-    valarray& operator+= (const valarray& v);
-    valarray& operator-= (const valarray& v);
-    valarray& operator^= (const valarray& v);
-    valarray& operator|= (const valarray& v);
-    valarray& operator&= (const valarray& v);
-    valarray& operator<<=(const valarray& v);
-    valarray& operator>>=(const valarray& v);
-
-    // member functions:
-    void swap(valarray& v) noexcept;
-
-    size_t size() const;
-
-    value_type sum() const;
-    value_type min() const;
-    value_type max() const;
-
-    valarray shift (int i) const;
-    valarray cshift(int i) const;
-    valarray apply(value_type f(value_type)) const;
-    valarray apply(value_type f(const value_type&)) const;
-    void resize(size_t n, value_type x = value_type());
-};
-
-class slice
-{
-public:
-    slice();
-    slice(size_t start, size_t size, size_t stride);
-
-    size_t start()  const;
-    size_t size()   const;
-    size_t stride() const;
-};
-
-template <class T>
-class slice_array
-{
-public:
-    typedef T value_type;
-
-    const slice_array& operator=(const slice_array& sa) const;
-    void operator=  (const valarray<value_type>& v) const;
-    void operator*= (const valarray<value_type>& v) const;
-    void operator/= (const valarray<value_type>& v) const;
-    void operator%= (const valarray<value_type>& v) const;
-    void operator+= (const valarray<value_type>& v) const;
-    void operator-= (const valarray<value_type>& v) const;
-    void operator^= (const valarray<value_type>& v) const;
-    void operator&= (const valarray<value_type>& v) const;
-    void operator|= (const valarray<value_type>& v) const;
-    void operator<<=(const valarray<value_type>& v) const;
-    void operator>>=(const valarray<value_type>& v) const;
-
-    void operator=(const value_type& x) const;
-    void operator=(const valarray<T>& val_arr) const;
-
-    slice_array() = delete;
-};
-
-class gslice
-{
-public:
-    gslice();
-    gslice(size_t start, const valarray<size_t>& size,
-                         const valarray<size_t>& stride);
-
-    size_t           start()  const;
-    valarray<size_t> size()   const;
-    valarray<size_t> stride() const;
-};
-
-template <class T>
-class gslice_array
-{
-public:
-    typedef T value_type;
-
-    void operator=  (const valarray<value_type>& v) const;
-    void operator*= (const valarray<value_type>& v) const;
-    void operator/= (const valarray<value_type>& v) const;
-    void operator%= (const valarray<value_type>& v) const;
-    void operator+= (const valarray<value_type>& v) const;
-    void operator-= (const valarray<value_type>& v) const;
-    void operator^= (const valarray<value_type>& v) const;
-    void operator&= (const valarray<value_type>& v) const;
-    void operator|= (const valarray<value_type>& v) const;
-    void operator<<=(const valarray<value_type>& v) const;
-    void operator>>=(const valarray<value_type>& v) const;
-
-    gslice_array(const gslice_array& ga);
-    ~gslice_array();
-    const gslice_array& operator=(const gslice_array& ga) const;
-    void operator=(const value_type& x) const;
-
-    gslice_array() = delete;
-};
-
-template <class T>
-class mask_array
-{
-public:
-    typedef T value_type;
-
-    void operator=  (const valarray<value_type>& v) const;
-    void operator*= (const valarray<value_type>& v) const;
-    void operator/= (const valarray<value_type>& v) const;
-    void operator%= (const valarray<value_type>& v) const;
-    void operator+= (const valarray<value_type>& v) const;
-    void operator-= (const valarray<value_type>& v) const;
-    void operator^= (const valarray<value_type>& v) const;
-    void operator&= (const valarray<value_type>& v) const;
-    void operator|= (const valarray<value_type>& v) const;
-    void operator<<=(const valarray<value_type>& v) const;
-    void operator>>=(const valarray<value_type>& v) const;
-
-    mask_array(const mask_array& ma);
-    ~mask_array();
-    const mask_array& operator=(const mask_array& ma) const;
-    void operator=(const value_type& x) const;
-
-    mask_array() = delete;
-};
-
-template <class T>
-class indirect_array
-{
-public:
-    typedef T value_type;
-
-    void operator=  (const valarray<value_type>& v) const;
-    void operator*= (const valarray<value_type>& v) const;
-    void operator/= (const valarray<value_type>& v) const;
-    void operator%= (const valarray<value_type>& v) const;
-    void operator+= (const valarray<value_type>& v) const;
-    void operator-= (const valarray<value_type>& v) const;
-    void operator^= (const valarray<value_type>& v) const;
-    void operator&= (const valarray<value_type>& v) const;
-    void operator|= (const valarray<value_type>& v) const;
-    void operator<<=(const valarray<value_type>& v) const;
-    void operator>>=(const valarray<value_type>& v) const;
-
-    indirect_array(const indirect_array& ia);
-    ~indirect_array();
-    const indirect_array& operator=(const indirect_array& ia) const;
-    void operator=(const value_type& x) const;
-
-    indirect_array() = delete;
-};
-
-template<class T> void swap(valarray<T>& x, valarray<T>& y) noexcept;
-
-template<class T> valarray<T> operator* (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator* (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator* (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator/ (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator/ (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator/ (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator% (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator% (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator% (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator+ (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator+ (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator+ (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator- (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator- (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator- (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator^ (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator^ (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator^ (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator& (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator& (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator& (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator| (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator| (const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator| (const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator<<(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator<<(const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator<<(const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> operator>>(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> operator>>(const valarray<T>& x, const T& y);
-template<class T> valarray<T> operator>>(const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator&&(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator&&(const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator&&(const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator||(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator||(const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator||(const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator==(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator==(const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator==(const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator!=(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator!=(const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator!=(const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator< (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator< (const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator< (const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator> (const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator> (const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator> (const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator<=(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator<=(const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator<=(const T& x, const valarray<T>& y);
-
-template<class T> valarray<bool> operator>=(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<bool> operator>=(const valarray<T>& x, const T& y);
-template<class T> valarray<bool> operator>=(const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> abs (const valarray<T>& x);
-template<class T> valarray<T> acos (const valarray<T>& x);
-template<class T> valarray<T> asin (const valarray<T>& x);
-template<class T> valarray<T> atan (const valarray<T>& x);
-
-template<class T> valarray<T> atan2(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> atan2(const valarray<T>& x, const T& y);
-template<class T> valarray<T> atan2(const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> cos (const valarray<T>& x);
-template<class T> valarray<T> cosh (const valarray<T>& x);
-template<class T> valarray<T> exp (const valarray<T>& x);
-template<class T> valarray<T> log (const valarray<T>& x);
-template<class T> valarray<T> log10(const valarray<T>& x);
-
-template<class T> valarray<T> pow(const valarray<T>& x, const valarray<T>& y);
-template<class T> valarray<T> pow(const valarray<T>& x, const T& y);
-template<class T> valarray<T> pow(const T& x, const valarray<T>& y);
-
-template<class T> valarray<T> sin (const valarray<T>& x);
-template<class T> valarray<T> sinh (const valarray<T>& x);
-template<class T> valarray<T> sqrt (const valarray<T>& x);
-template<class T> valarray<T> tan (const valarray<T>& x);
-template<class T> valarray<T> tanh (const valarray<T>& x);
-
-template <class T> unspecified1 begin(valarray<T>& v);
-template <class T> unspecified2 begin(const valarray<T>& v);
-template <class T> unspecified1 end(valarray<T>& v);
-template <class T> unspecified2 end(const valarray<T>& v);
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/valarray.syn.
 
 #include <__config>
 #include <algorithm>
diff --git a/libcxx/include/variant b/libcxx/include/variant
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -10,194 +10,7 @@
 #ifndef _LIBCPP_VARIANT
 #define _LIBCPP_VARIANT
 
-/*
-   variant synopsis
-
-namespace std {
-
-  // 20.7.2, class template variant
-  template <class... Types>
-  class variant {
-  public:
-
-    // 20.7.2.1, constructors
-    constexpr variant() noexcept(see below);
-    variant(const variant&);                // constexpr in C++20
-    variant(variant&&) noexcept(see below); // constexpr in C++20
-
-    template <class T> constexpr variant(T&&) noexcept(see below);
-
-    template <class T, class... Args>
-    constexpr explicit variant(in_place_type_t<T>, Args&&...);
-
-    template <class T, class U, class... Args>
-    constexpr explicit variant(
-        in_place_type_t<T>, initializer_list<U>, Args&&...);
-
-    template <size_t I, class... Args>
-    constexpr explicit variant(in_place_index_t<I>, Args&&...);
-
-    template <size_t I, class U, class... Args>
-    constexpr explicit variant(
-        in_place_index_t<I>, initializer_list<U>, Args&&...);
-
-    // 20.7.2.2, destructor
-    ~variant();
-
-    // 20.7.2.3, assignment
-    variant& operator=(const variant&);                // constexpr in C++20
-    variant& operator=(variant&&) noexcept(see below); // constexpr in C++20
-
-    template <class T> variant& operator=(T&&) noexcept(see below);
-
-    // 20.7.2.4, modifiers
-    template <class T, class... Args>
-    T& emplace(Args&&...);
-
-    template <class T, class U, class... Args>
-    T& emplace(initializer_list<U>, Args&&...);
-
-    template <size_t I, class... Args>
-    variant_alternative_t<I, variant>& emplace(Args&&...);
-
-    template <size_t I, class U, class...  Args>
-    variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...);
-
-    // 20.7.2.5, value status
-    constexpr bool valueless_by_exception() const noexcept;
-    constexpr size_t index() const noexcept;
-
-    // 20.7.2.6, swap
-    void swap(variant&) noexcept(see below);
-  };
-
-  // 20.7.3, variant helper classes
-  template <class T> struct variant_size; // undefined
-
-  template <class T>
-  inline constexpr size_t variant_size_v = variant_size<T>::value;
-
-  template <class T> struct variant_size<const T>;
-  template <class T> struct variant_size<volatile T>;
-  template <class T> struct variant_size<const volatile T>;
-
-  template <class... Types>
-  struct variant_size<variant<Types...>>;
-
-  template <size_t I, class T> struct variant_alternative; // undefined
-
-  template <size_t I, class T>
-  using variant_alternative_t = typename variant_alternative<I, T>::type;
-
-  template <size_t I, class T> struct variant_alternative<I, const T>;
-  template <size_t I, class T> struct variant_alternative<I, volatile T>;
-  template <size_t I, class T> struct variant_alternative<I, const volatile T>;
-
-  template <size_t I, class... Types>
-  struct variant_alternative<I, variant<Types...>>;
-
-  inline constexpr size_t variant_npos = -1;
-
-  // 20.7.4, value access
-  template <class T, class... Types>
-  constexpr bool holds_alternative(const variant<Types...>&) noexcept;
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>>&
-  get(variant<Types...>&);
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>>&&
-  get(variant<Types...>&&);
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>> const&
-  get(const variant<Types...>&);
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>> const&&
-  get(const variant<Types...>&&);
-
-  template <class T, class...  Types>
-  constexpr T& get(variant<Types...>&);
-
-  template <class T, class... Types>
-  constexpr T&& get(variant<Types...>&&);
-
-  template <class T, class... Types>
-  constexpr const T& get(const variant<Types...>&);
-
-  template <class T, class... Types>
-  constexpr const T&& get(const variant<Types...>&&);
-
-  template <size_t I, class... Types>
-  constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
-  get_if(variant<Types...>*) noexcept;
-
-  template <size_t I, class... Types>
-  constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
-  get_if(const variant<Types...>*) noexcept;
-
-  template <class T, class... Types>
-  constexpr add_pointer_t<T>
-  get_if(variant<Types...>*) noexcept;
-
-  template <class T, class... Types>
-  constexpr add_pointer_t<const T>
-  get_if(const variant<Types...>*) noexcept;
-
-  // 20.7.5, relational operators
-  template <class... Types>
-  constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
-
-  // 20.7.6, visitation
-  template <class Visitor, class... Variants>
-  constexpr see below visit(Visitor&&, Variants&&...);
-
-  template <class R, class Visitor, class... Variants>
-  constexpr R visit(Visitor&&, Variants&&...); // since C++20
-
-  // 20.7.7, class monostate
-  struct monostate;
-
-  // 20.7.8, monostate relational operators
-  constexpr bool operator<(monostate, monostate) noexcept;
-  constexpr bool operator>(monostate, monostate) noexcept;
-  constexpr bool operator<=(monostate, monostate) noexcept;
-  constexpr bool operator>=(monostate, monostate) noexcept;
-  constexpr bool operator==(monostate, monostate) noexcept;
-  constexpr bool operator!=(monostate, monostate) noexcept;
-
-  // 20.7.9, specialized algorithms
-  template <class... Types>
-  void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
-
-  // 20.7.10, class bad_variant_access
-  class bad_variant_access;
-
-  // 20.7.11, hash support
-  template <class T> struct hash;
-  template <class... Types> struct hash<variant<Types...>>;
-  template <> struct hash<monostate>;
-
-} // namespace std
-
-*/
+// Synopsis avaiable at http://wg21.link/variant.syn.
 
 #include <__availability>
 #include <__config>
diff --git a/libcxx/include/vector b/libcxx/include/vector
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -10,266 +10,7 @@
 #ifndef _LIBCPP_VECTOR
 #define _LIBCPP_VECTOR
 
-/*
-    vector synopsis
-
-namespace std
-{
-
-template <class T, class Allocator = allocator<T> >
-class vector
-{
-public:
-    typedef T                                        value_type;
-    typedef Allocator                                allocator_type;
-    typedef typename allocator_type::reference       reference;
-    typedef typename allocator_type::const_reference const_reference;
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-    typedef typename allocator_type::pointer         pointer;
-    typedef typename allocator_type::const_pointer   const_pointer;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-
-    vector()
-        noexcept(is_nothrow_default_constructible<allocator_type>::value);
-    explicit vector(const allocator_type&);
-    explicit vector(size_type n);
-    explicit vector(size_type n, const allocator_type&); // C++14
-    vector(size_type n, const value_type& value, const allocator_type& = allocator_type());
-    template <class InputIterator>
-        vector(InputIterator first, InputIterator last, const allocator_type& = allocator_type());
-    vector(const vector& x);
-    vector(vector&& x)
-        noexcept(is_nothrow_move_constructible<allocator_type>::value);
-    vector(initializer_list<value_type> il);
-    vector(initializer_list<value_type> il, const allocator_type& a);
-    ~vector();
-    vector& operator=(const vector& x);
-    vector& operator=(vector&& x)
-        noexcept(
-             allocator_type::propagate_on_container_move_assignment::value ||
-             allocator_type::is_always_equal::value); // C++17
-    vector& operator=(initializer_list<value_type> il);
-    template <class InputIterator>
-        void assign(InputIterator first, InputIterator last);
-    void assign(size_type n, const value_type& u);
-    void assign(initializer_list<value_type> il);
-
-    allocator_type get_allocator() const noexcept;
-
-    iterator               begin() noexcept;
-    const_iterator         begin()   const noexcept;
-    iterator               end() noexcept;
-    const_iterator         end()     const noexcept;
-
-    reverse_iterator       rbegin() noexcept;
-    const_reverse_iterator rbegin()  const noexcept;
-    reverse_iterator       rend() noexcept;
-    const_reverse_iterator rend()    const noexcept;
-
-    const_iterator         cbegin()  const noexcept;
-    const_iterator         cend()    const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend()   const noexcept;
-
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-    size_type capacity() const noexcept;
-    bool empty() const noexcept;
-    void reserve(size_type n);
-    void shrink_to_fit() noexcept;
-
-    reference       operator[](size_type n);
-    const_reference operator[](size_type n) const;
-    reference       at(size_type n);
-    const_reference at(size_type n) const;
-
-    reference       front();
-    const_reference front() const;
-    reference       back();
-    const_reference back() const;
-
-    value_type*       data() noexcept;
-    const value_type* data() const noexcept;
-
-    void push_back(const value_type& x);
-    void push_back(value_type&& x);
-    template <class... Args>
-        reference emplace_back(Args&&... args); // reference in C++17
-    void pop_back();
-
-    template <class... Args> iterator emplace(const_iterator position, Args&&... args);
-    iterator insert(const_iterator position, const value_type& x);
-    iterator insert(const_iterator position, value_type&& x);
-    iterator insert(const_iterator position, size_type n, const value_type& x);
-    template <class InputIterator>
-        iterator insert(const_iterator position, InputIterator first, InputIterator last);
-    iterator insert(const_iterator position, initializer_list<value_type> il);
-
-    iterator erase(const_iterator position);
-    iterator erase(const_iterator first, const_iterator last);
-
-    void clear() noexcept;
-
-    void resize(size_type sz);
-    void resize(size_type sz, const value_type& c);
-
-    void swap(vector&)
-        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
-                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
-
-    bool __invariants() const;
-};
-
-template <class Allocator = allocator<T> >
-class vector<bool, Allocator>
-{
-public:
-    typedef bool                                     value_type;
-    typedef Allocator                                allocator_type;
-    typedef implementation-defined                   iterator;
-    typedef implementation-defined                   const_iterator;
-    typedef typename allocator_type::size_type       size_type;
-    typedef typename allocator_type::difference_type difference_type;
-    typedef iterator                                 pointer;
-    typedef const_iterator                           const_pointer;
-    typedef std::reverse_iterator<iterator>          reverse_iterator;
-    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
-
-    class reference
-    {
-    public:
-        reference(const reference&) noexcept;
-        operator bool() const noexcept;
-        reference& operator=(const bool x) noexcept;
-        reference& operator=(const reference& x) noexcept;
-        iterator operator&() const noexcept;
-        void flip() noexcept;
-    };
-
-    class const_reference
-    {
-    public:
-        const_reference(const reference&) noexcept;
-        operator bool() const noexcept;
-        const_iterator operator&() const noexcept;
-    };
-
-    vector()
-        noexcept(is_nothrow_default_constructible<allocator_type>::value);
-    explicit vector(const allocator_type&);
-    explicit vector(size_type n, const allocator_type& a = allocator_type()); // C++14
-    vector(size_type n, const value_type& value, const allocator_type& = allocator_type());
-    template <class InputIterator>
-        vector(InputIterator first, InputIterator last, const allocator_type& = allocator_type());
-    vector(const vector& x);
-    vector(vector&& x)
-        noexcept(is_nothrow_move_constructible<allocator_type>::value);
-    vector(initializer_list<value_type> il);
-    vector(initializer_list<value_type> il, const allocator_type& a);
-    ~vector();
-    vector& operator=(const vector& x);
-    vector& operator=(vector&& x)
-        noexcept(
-             allocator_type::propagate_on_container_move_assignment::value ||
-             allocator_type::is_always_equal::value); // C++17
-    vector& operator=(initializer_list<value_type> il);
-    template <class InputIterator>
-        void assign(InputIterator first, InputIterator last);
-    void assign(size_type n, const value_type& u);
-    void assign(initializer_list<value_type> il);
-
-    allocator_type get_allocator() const noexcept;
-
-    iterator               begin() noexcept;
-    const_iterator         begin()   const noexcept;
-    iterator               end() noexcept;
-    const_iterator         end()     const noexcept;
-
-    reverse_iterator       rbegin() noexcept;
-    const_reverse_iterator rbegin()  const noexcept;
-    reverse_iterator       rend() noexcept;
-    const_reverse_iterator rend()    const noexcept;
-
-    const_iterator         cbegin()  const noexcept;
-    const_iterator         cend()    const noexcept;
-    const_reverse_iterator crbegin() const noexcept;
-    const_reverse_iterator crend()   const noexcept;
-
-    size_type size() const noexcept;
-    size_type max_size() const noexcept;
-    size_type capacity() const noexcept;
-    bool empty() const noexcept;
-    void reserve(size_type n);
-    void shrink_to_fit() noexcept;
-
-    reference       operator[](size_type n);
-    const_reference operator[](size_type n) const;
-    reference       at(size_type n);
-    const_reference at(size_type n) const;
-
-    reference       front();
-    const_reference front() const;
-    reference       back();
-    const_reference back() const;
-
-    void push_back(const value_type& x);
-    template <class... Args> reference emplace_back(Args&&... args);  // C++14; reference in C++17
-    void pop_back();
-
-    template <class... Args> iterator emplace(const_iterator position, Args&&... args);  // C++14
-    iterator insert(const_iterator position, const value_type& x);
-    iterator insert(const_iterator position, size_type n, const value_type& x);
-    template <class InputIterator>
-        iterator insert(const_iterator position, InputIterator first, InputIterator last);
-    iterator insert(const_iterator position, initializer_list<value_type> il);
-
-    iterator erase(const_iterator position);
-    iterator erase(const_iterator first, const_iterator last);
-
-    void clear() noexcept;
-
-    void resize(size_type sz);
-    void resize(size_type sz, value_type x);
-
-    void swap(vector&)
-        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
-                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
-    void flip() noexcept;
-
-    bool __invariants() const;
-};
-
-template <class InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-   vector(InputIterator, InputIterator, Allocator = Allocator())
-   -> vector<typename iterator_traits<InputIterator>::value_type, Allocator>;
-
-template <class Allocator> struct hash<std::vector<bool, Allocator>>;
-
-template <class T, class Allocator> bool operator==(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
-template <class T, class Allocator> bool operator< (const vector<T,Allocator>& x, const vector<T,Allocator>& y);
-template <class T, class Allocator> bool operator!=(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
-template <class T, class Allocator> bool operator> (const vector<T,Allocator>& x, const vector<T,Allocator>& y);
-template <class T, class Allocator> bool operator>=(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
-template <class T, class Allocator> bool operator<=(const vector<T,Allocator>& x, const vector<T,Allocator>& y);
-
-template <class T, class Allocator>
-void swap(vector<T,Allocator>& x, vector<T,Allocator>& y)
-    noexcept(noexcept(x.swap(y)));
-
-template <class T, class Allocator, class U>
-typename vector<T, Allocator>::size_type
-erase(vector<T, Allocator>& c, const U& value);       // C++20
-template <class T, class Allocator, class Predicate>
-typename vector<T, Allocator>::size_type
-erase_if(vector<T, Allocator>& c, Predicate pred);    // C++20
-
-}  // std
-
-*/
+// Synopsis avaiable at http://wg21.link/vector.syn.
 
 #include <__config>
 #include <__bit_reference>
diff --git a/libcxx/include/version b/libcxx/include/version
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -10,160 +10,7 @@
 #ifndef _LIBCPP_VERSIONH
 #define _LIBCPP_VERSIONH
 
-/*
-  version synopsis
-
-Macro name                                              Value   Headers
-__cpp_lib_addressof_constexpr                           201603L <memory>
-__cpp_lib_allocator_traits_is_always_equal              201411L <deque> <forward_list> <list>
-                                                                <map> <memory> <scoped_allocator>
-                                                                <set> <string> <unordered_map>
-                                                                <unordered_set> <vector>
-__cpp_lib_any                                           201606L <any>
-__cpp_lib_apply                                         201603L <tuple>
-__cpp_lib_array_constexpr                               201811L <array> <iterator>
-                                                        201603L // C++17
-__cpp_lib_as_const                                      201510L <utility>
-__cpp_lib_assume_aligned                                201811L <memory>
-__cpp_lib_atomic_flag_test                              201907L <atomic>
-__cpp_lib_atomic_float                                  201711L <atomic>
-__cpp_lib_atomic_is_always_lock_free                    201603L <atomic>
-__cpp_lib_atomic_lock_free_type_aliases                 201907L <atomic>
-__cpp_lib_atomic_ref                                    201806L <atomic>
-__cpp_lib_atomic_shared_ptr                             201711L <atomic>
-__cpp_lib_atomic_value_initialization                   201911L <atomic> <memory>
-__cpp_lib_atomic_wait                                   201907L <atomic>
-__cpp_lib_barrier                                       201907L <barrier>
-__cpp_lib_bind_front                                    201907L <functional>
-__cpp_lib_bit_cast                                      201806L <bit>
-__cpp_lib_bitops                                        201907L <bit>
-__cpp_lib_bool_constant                                 201505L <type_traits>
-__cpp_lib_bounded_array_traits                          201902L <type_traits>
-__cpp_lib_boyer_moore_searcher                          201603L <functional>
-__cpp_lib_byte                                          201603L <cstddef>
-__cpp_lib_char8_t                                       201811L <atomic> <filesystem> <istream>
-                                                                <limits> <locale> <ostream>
-                                                                <string> <string_view>
-__cpp_lib_chrono                                        201611L <chrono>
-__cpp_lib_chrono_udls                                   201304L <chrono>
-__cpp_lib_clamp                                         201603L <algorithm>
-__cpp_lib_complex_udls                                  201309L <complex>
-__cpp_lib_concepts                                      202002L <concepts>
-__cpp_lib_constexpr_algorithms                          201806L <algorithm>
-__cpp_lib_constexpr_complex                             201711L <complex>
-__cpp_lib_constexpr_dynamic_alloc                       201907L <memory>
-__cpp_lib_constexpr_functional                          201907L <functional>
-__cpp_lib_constexpr_iterator                            201811L <iterator>
-__cpp_lib_constexpr_memory                              201811L <memory>
-__cpp_lib_constexpr_numeric                             201911L <numeric>
-__cpp_lib_constexpr_string                              201811L <string>
-__cpp_lib_constexpr_string_view                         201811L <string_view>
-__cpp_lib_constexpr_tuple                               201811L <tuple>
-__cpp_lib_constexpr_utility                             201811L <utility>
-__cpp_lib_constexpr_vector                              201907L <vector>
-__cpp_lib_coroutine                                     201902L <coroutine>
-__cpp_lib_destroying_delete                             201806L <new>
-__cpp_lib_enable_shared_from_this                       201603L <memory>
-__cpp_lib_endian                                        201907L <bit>
-__cpp_lib_erase_if                                      202002L <deque> <forward_list> <list>
-                                                                <map> <set> <string>
-                                                                <unordered_map> <unordered_set> <vector>
-__cpp_lib_exchange_function                             201304L <utility>
-__cpp_lib_execution                                     201902L <execution>
-                                                        201603L // C++17
-__cpp_lib_filesystem                                    201703L <filesystem>
-__cpp_lib_format                                        201907L <format>
-__cpp_lib_gcd_lcm                                       201606L <numeric>
-__cpp_lib_generic_associative_lookup                    201304L <map> <set>
-__cpp_lib_generic_unordered_lookup                      201811L <unordered_map> <unordered_set>
-__cpp_lib_hardware_interference_size                    201703L <new>
-__cpp_lib_has_unique_object_representations             201606L <type_traits>
-__cpp_lib_hypot                                         201603L <cmath>
-__cpp_lib_incomplete_container_elements                 201505L <forward_list> <list> <vector>
-__cpp_lib_int_pow2                                      202002L <bit>
-__cpp_lib_integer_comparison_functions                  202002L <utility>
-__cpp_lib_integer_sequence                              201304L <utility>
-__cpp_lib_integral_constant_callable                    201304L <type_traits>
-__cpp_lib_interpolate                                   201902L <cmath> <numeric>
-__cpp_lib_invoke                                        201411L <functional>
-__cpp_lib_is_aggregate                                  201703L <type_traits>
-__cpp_lib_is_constant_evaluated                         201811L <type_traits>
-__cpp_lib_is_final                                      201402L <type_traits>
-__cpp_lib_is_invocable                                  201703L <type_traits>
-__cpp_lib_is_layout_compatible                          201907L <type_traits>
-__cpp_lib_is_nothrow_convertible                        201806L <type_traits>
-__cpp_lib_is_null_pointer                               201309L <type_traits>
-__cpp_lib_is_pointer_interconvertible                   201907L <type_traits>
-__cpp_lib_is_scoped_enum                                202011L <type_traits>
-__cpp_lib_is_swappable                                  201603L <type_traits>
-__cpp_lib_jthread                                       201911L <stop_token> <thread>
-__cpp_lib_latch                                         201907L <latch>
-__cpp_lib_launder                                       201606L <new>
-__cpp_lib_list_remove_return_type                       201806L <forward_list> <list>
-__cpp_lib_logical_traits                                201510L <type_traits>
-__cpp_lib_make_from_tuple                               201606L <tuple>
-__cpp_lib_make_reverse_iterator                         201402L <iterator>
-__cpp_lib_make_unique                                   201304L <memory>
-__cpp_lib_map_try_emplace                               201411L <map>
-__cpp_lib_math_constants                                201907L <numbers>
-__cpp_lib_math_special_functions                        201603L <cmath>
-__cpp_lib_memory_resource                               201603L <memory_resource>
-__cpp_lib_node_extract                                  201606L <map> <set> <unordered_map>
-                                                                <unordered_set>
-__cpp_lib_nonmember_container_access                    201411L <array> <deque> <forward_list>
-                                                                <iterator> <list> <map>
-                                                                <regex> <set> <string>
-                                                                <unordered_map> <unordered_set> <vector>
-__cpp_lib_not_fn                                        201603L <functional>
-__cpp_lib_null_iterators                                201304L <iterator>
-__cpp_lib_optional                                      201606L <optional>
-__cpp_lib_parallel_algorithm                            201603L <algorithm> <numeric>
-__cpp_lib_polymorphic_allocator                         201902L <memory>
-__cpp_lib_quoted_string_io                              201304L <iomanip>
-__cpp_lib_ranges                                        201811L <algorithm> <functional> <iterator>
-                                                                <memory> <ranges>
-__cpp_lib_raw_memory_algorithms                         201606L <memory>
-__cpp_lib_remove_cvref                                  201711L <type_traits>
-__cpp_lib_result_of_sfinae                              201210L <functional> <type_traits>
-__cpp_lib_robust_nonmodifying_seq_ops                   201304L <algorithm>
-__cpp_lib_sample                                        201603L <algorithm>
-__cpp_lib_scoped_lock                                   201703L <mutex>
-__cpp_lib_semaphore                                     201907L <semaphore>
-__cpp_lib_shared_mutex                                  201505L <shared_mutex>
-__cpp_lib_shared_ptr_arrays                             201611L <memory>
-__cpp_lib_shared_ptr_weak_type                          201606L <memory>
-__cpp_lib_shared_timed_mutex                            201402L <shared_mutex>
-__cpp_lib_shift                                         201806L <algorithm>
-__cpp_lib_smart_ptr_for_overwrite                       202002L <memory>
-__cpp_lib_source_location                               201907L <source_location>
-__cpp_lib_span                                          202002L <span>
-__cpp_lib_ssize                                         201902L <iterator>
-__cpp_lib_stacktrace                                    202011L <stacktrace>
-__cpp_lib_starts_ends_with                              201711L <string> <string_view>
-__cpp_lib_stdatomic_h                                   202011L <stdatomic.h>
-__cpp_lib_string_contains                               202011L <string> <string_view>
-__cpp_lib_string_udls                                   201304L <string>
-__cpp_lib_string_view                                   201803L <string> <string_view>
-                                                        201606L // C++17
-__cpp_lib_syncbuf                                       201803L <syncstream>
-__cpp_lib_three_way_comparison                          201907L <compare>
-__cpp_lib_to_address                                    201711L <memory>
-__cpp_lib_to_array                                      201907L <array>
-__cpp_lib_to_chars                                      201611L <utility>
-__cpp_lib_to_underlying                                 202102L <utility>
-__cpp_lib_transformation_trait_aliases                  201304L <type_traits>
-__cpp_lib_transparent_operators                         201510L <functional> <memory>
-                                                        201210L // C++14
-__cpp_lib_tuple_element_t                               201402L <tuple>
-__cpp_lib_tuples_by_type                                201304L <tuple> <utility>
-__cpp_lib_type_trait_variable_templates                 201510L <type_traits>
-__cpp_lib_uncaught_exceptions                           201411L <exception>
-__cpp_lib_unordered_map_try_emplace                     201411L <unordered_map>
-__cpp_lib_unwrap_ref                                    201811L <functional>
-__cpp_lib_variant                                       202102L <variant>
-__cpp_lib_void_t                                        201411L <type_traits>
-
-*/
+// Synopsis avaiable at http://wg21.link/version.syn.
 
 #include <__config>