diff --git a/libcxx/include/__functional_base b/libcxx/include/__functional_base
--- a/libcxx/include/__functional_base
+++ b/libcxx/include/__functional_base
@@ -11,10 +11,10 @@
 #define _LIBCPP_FUNCTIONAL_BASE
 
 #include <__config>
-#include <type_traits>
-#include <typeinfo>
 #include <exception>
 #include <new>
+#include <type_traits>
+#include <typeinfo>
 #include <utility>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__hash_table b/libcxx/include/__hash_table
--- a/libcxx/include/__hash_table
+++ b/libcxx/include/__hash_table
@@ -10,16 +10,16 @@
 #ifndef _LIBCPP__HASH_TABLE
 #define _LIBCPP__HASH_TABLE
 
+#include <__bits> // __libcpp_clz
 #include <__config>
-#include <initializer_list>
-#include <memory>
-#include <iterator>
+#include <__debug>
 #include <algorithm>
 #include <cmath>
-#include <utility>
+#include <initializer_list>
+#include <iterator>
+#include <memory>
 #include <type_traits>
-
-#include <__debug>
+#include <utility>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/__iterator/iterator_traits.h b/libcxx/include/__iterator/iterator_traits.h
--- a/libcxx/include/__iterator/iterator_traits.h
+++ b/libcxx/include/__iterator/iterator_traits.h
@@ -428,7 +428,7 @@
 
 template <class _Tp, class _Up, bool = __has_iterator_category<iterator_traits<_Tp> >::value>
 struct __has_iterator_category_convertible_to
-    : _BoolConstant<is_convertible<typename iterator_traits<_Tp>::iterator_category, _Up>::value>
+    : is_convertible<typename iterator_traits<_Tp>::iterator_category, _Up>
 {};
 
 template <class _Tp, class _Up>
@@ -436,7 +436,7 @@
 
 template <class _Tp, class _Up, bool = __has_iterator_concept<_Tp>::value>
 struct __has_iterator_concept_convertible_to
-    : _BoolConstant<is_convertible<typename _Tp::iterator_concept, _Up>::value>
+    : is_convertible<typename _Tp::iterator_concept, _Up>
 {};
 
 template <class _Tp, class _Up>
@@ -454,10 +454,11 @@
 template <class _Tp>
 struct __is_cpp17_random_access_iterator : public __has_iterator_category_convertible_to<_Tp, random_access_iterator_tag> {};
 
-// __is_cpp17_contiguous_iterator determines if an iterator is contiguous,
-// either because it advertises itself as such (in C++20) or because it
-// is a pointer type or a known trivial wrapper around a pointer type,
-// such as __wrap_iter<T*>.
+// __is_cpp17_contiguous_iterator determines if an iterator is known by
+// libc++ to be contiguous, either because it advertises itself as such
+// (in C++20) or because it is a pointer type or a known trivial wrapper
+// around a pointer type, such as __wrap_iter<T*>. Such iterators receive
+// special "contiguous" optimizations in std::copy and std::sort.
 //
 #if _LIBCPP_STD_VER > 17
 template <class _Tp>
diff --git a/libcxx/include/__locale b/libcxx/include/__locale
--- a/libcxx/include/__locale
+++ b/libcxx/include/__locale
@@ -10,8 +10,8 @@
 #ifndef _LIBCPP___LOCALE
 #define _LIBCPP___LOCALE
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <string>
 #include <memory>
 #include <utility>
diff --git a/libcxx/include/__mutex_base b/libcxx/include/__mutex_base
--- a/libcxx/include/__mutex_base
+++ b/libcxx/include/__mutex_base
@@ -11,9 +11,9 @@
 #define _LIBCPP___MUTEX_BASE
 
 #include <__config>
+#include <__threading_support>
 #include <chrono>
 #include <system_error>
-#include <__threading_support>
 
 #include <time.h>
 
diff --git a/libcxx/include/__split_buffer b/libcxx/include/__split_buffer
--- a/libcxx/include/__split_buffer
+++ b/libcxx/include/__split_buffer
@@ -3,8 +3,8 @@
 #define _LIBCPP_SPLIT_BUFFER
 
 #include <__config>
-#include <type_traits>
 #include <algorithm>
+#include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/__std_stream b/libcxx/include/__std_stream
--- a/libcxx/include/__std_stream
+++ b/libcxx/include/__std_stream
@@ -11,10 +11,10 @@
 #define _LIBCPP___STD_STREAM
 
 #include <__config>
-#include <ostream>
-#include <istream>
 #include <__locale>
 #include <cstdio>
+#include <istream>
+#include <ostream>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/__threading_support b/libcxx/include/__threading_support
--- a/libcxx/include/__threading_support
+++ b/libcxx/include/__threading_support
@@ -10,11 +10,11 @@
 #ifndef _LIBCPP_THREADING_SUPPORT
 #define _LIBCPP_THREADING_SUPPORT
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <chrono>
-#include <iosfwd>
 #include <errno.h>
+#include <iosfwd>
 #include <limits>
 
 #ifdef __MVS__
diff --git a/libcxx/include/__tree b/libcxx/include/__tree
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -11,10 +11,10 @@
 #define _LIBCPP___TREE
 
 #include <__config>
+#include <algorithm>
 #include <iterator>
 #include <memory>
 #include <stdexcept>
-#include <algorithm>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -646,15 +646,15 @@
 */
 
 #include <__config>
-#include <initializer_list>
-#include <type_traits>
+#include <__bits> // __libcpp_clz
+#include <cstddef>
 #include <cstring>
-#include <utility> // needed to provide swap_ranges.
-#include <memory>
 #include <functional>
+#include <initializer_list>
 #include <iterator>
-#include <cstddef>
-#include <bit>
+#include <memory>
+#include <type_traits>
+#include <utility> // swap_ranges
 #include <version>
 
 #include <__debug>
diff --git a/libcxx/include/any b/libcxx/include/any
--- a/libcxx/include/any
+++ b/libcxx/include/any
@@ -80,12 +80,12 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
+#include <cstdlib>
 #include <memory>
-#include <typeinfo>
 #include <type_traits>
-#include <cstdlib>
+#include <typeinfo>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/array b/libcxx/include/array
--- a/libcxx/include/array
+++ b/libcxx/include/array
@@ -109,25 +109,22 @@
 */
 
 #include <__config>
+#include <__debug>
 #include <__tuple>
-#include <type_traits>
-#include <utility>
-#include <iterator>
 #include <algorithm>
-#include <stdexcept>
 #include <cstdlib> // for _LIBCPP_UNREACHABLE
+#include <iterator>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
 #include <version>
-#include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
-
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-
 template <class _Tp, size_t _Size>
 struct _LIBCPP_TEMPLATE_VIS array
 {
diff --git a/libcxx/include/atomic b/libcxx/include/atomic
--- a/libcxx/include/atomic
+++ b/libcxx/include/atomic
@@ -574,8 +574,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__threading_support>
 #include <cstddef>
 #include <cstdint>
diff --git a/libcxx/include/barrier b/libcxx/include/barrier
--- a/libcxx/include/barrier
+++ b/libcxx/include/barrier
@@ -45,8 +45,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <atomic>
 #ifndef _LIBCPP_HAS_NO_TREE_BARRIER
 # include <memory>
diff --git a/libcxx/include/bit b/libcxx/include/bit
--- a/libcxx/include/bit
+++ b/libcxx/include/bit
@@ -55,7 +55,7 @@
 */
 
 #include <__config>
-#include <__bits>
+#include <__bits> // __libcpp_clz
 #include <__debug>
 #include <limits>
 #include <type_traits>
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -114,12 +114,12 @@
 
 #include <__config>
 #include <__bit_reference>
-#include <cstddef>
+#include <__functional_base>
 #include <climits>
-#include <string>
-#include <stdexcept>
+#include <cstddef>
 #include <iosfwd>
-#include <__functional_base>
+#include <stdexcept>
+#include <string>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/charconv b/libcxx/include/charconv
--- a/libcxx/include/charconv
+++ b/libcxx/include/charconv
@@ -73,8 +73,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__errc>
 #include <__utility/to_underlying.h>
 #include <cmath> // for log2f
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -823,13 +823,13 @@
 }  // std
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <compare>
 #include <ctime>
-#include <type_traits>
-#include <ratio>
 #include <limits>
+#include <ratio>
+#include <type_traits>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/complex b/libcxx/include/complex
--- a/libcxx/include/complex
+++ b/libcxx/include/complex
@@ -232,10 +232,10 @@
 */
 
 #include <__config>
-#include <type_traits>
-#include <stdexcept>
 #include <cmath>
 #include <iosfwd>
+#include <stdexcept>
+#include <type_traits>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
diff --git a/libcxx/include/exception b/libcxx/include/exception
--- a/libcxx/include/exception
+++ b/libcxx/include/exception
@@ -76,8 +76,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__memory/addressof.h>
 #include <cstddef>
 #include <cstdlib>
diff --git a/libcxx/include/filesystem b/libcxx/include/filesystem
--- a/libcxx/include/filesystem
+++ b/libcxx/include/filesystem
@@ -229,20 +229,21 @@
 
 */
 
-#include <__config>
 #include <__availability>
-#include <cstddef>
-#include <cstdlib>
+#include <__config>
+#include <__debug>
 #include <chrono>
 #include <compare>
-#include <iterator>
+#include <cstddef>
+#include <cstdlib>
 #include <iosfwd>
+#include <iterator>
 #include <memory>
 #include <stack>
 #include <string>
+#include <string_view>
 #include <system_error>
 #include <utility>
-#include <string_view>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
@@ -250,8 +251,6 @@
 # include <iomanip> // for quoted
 #endif
 
-#include <__debug>
-
 #if defined(_LIBCPP_HAS_NO_FILESYSTEM_LIBRARY)
 # error "The Filesystem library is not supported by this configuration of libc++"
 #endif
diff --git a/libcxx/include/forward_list b/libcxx/include/forward_list
--- a/libcxx/include/forward_list
+++ b/libcxx/include/forward_list
@@ -180,11 +180,11 @@
 */
 
 #include <__config>
+#include <algorithm>
 #include <initializer_list>
-#include <memory>
-#include <limits>
 #include <iterator>
-#include <algorithm>
+#include <limits>
+#include <memory>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
--- a/libcxx/include/fstream
+++ b/libcxx/include/fstream
@@ -179,8 +179,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__debug>
 #include <__locale>
 #include <cstdio>
diff --git a/libcxx/include/functional b/libcxx/include/functional
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -508,17 +508,16 @@
 
 #include <__config>
 #include <__debug>
+#include <__functional_base>
 #include <concepts>
-#include <type_traits>
-#include <typeinfo>
 #include <exception>
 #include <memory>
 #include <tuple>
+#include <type_traits>
+#include <typeinfo>
 #include <utility>
 #include <version>
 
-#include <__functional_base>
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
diff --git a/libcxx/include/future b/libcxx/include/future
--- a/libcxx/include/future
+++ b/libcxx/include/future
@@ -361,8 +361,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__debug>
 #include <chrono>
 #include <exception>
diff --git a/libcxx/include/ios b/libcxx/include/ios
--- a/libcxx/include/ios
+++ b/libcxx/include/ios
@@ -211,8 +211,8 @@
 */
 
 #include <__config>
-#include <iosfwd>
 #include <__locale>
+#include <iosfwd>
 #include <system_error>
 
 #if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
diff --git a/libcxx/include/iostream b/libcxx/include/iostream
--- a/libcxx/include/iostream
+++ b/libcxx/include/iostream
@@ -14,9 +14,9 @@
     iostream synopsis
 
 #include <ios>
-#include <streambuf>
 #include <istream>
 #include <ostream>
+#include <streambuf>
 
 namespace std {
 
@@ -35,9 +35,9 @@
 
 #include <__config>
 #include <ios>
-#include <streambuf>
 #include <istream>
 #include <ostream>
+#include <streambuf>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/istream b/libcxx/include/istream
--- a/libcxx/include/istream
+++ b/libcxx/include/istream
@@ -159,8 +159,8 @@
 */
 
 #include <__config>
-#include <version>
 #include <ostream>
+#include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -1294,8 +1294,7 @@
     typedef typename iterator_traits<iterator_type>::reference         reference;
     typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
 #if _LIBCPP_STD_VER > 17
-    typedef _If<__is_cpp17_contiguous_iterator<_Iter>::value,
-                contiguous_iterator_tag, iterator_category>            iterator_concept;
+    typedef contiguous_iterator_tag                                    iterator_concept;
 #endif
 
 private:
@@ -1473,12 +1472,12 @@
 
 #if _LIBCPP_STD_VER <= 17
 template <class _It>
-struct __is_cpp17_contiguous_iterator<__wrap_iter<_It> > : __is_cpp17_contiguous_iterator<_It> {};
+struct __is_cpp17_contiguous_iterator<__wrap_iter<_It> > : true_type {};
 #endif
 
 template <class _Iter>
 _LIBCPP_CONSTEXPR
-_EnableIf<__is_cpp17_contiguous_iterator<_Iter>::value, decltype(_VSTD::__to_address(declval<_Iter>()))>
+decltype(_VSTD::__to_address(declval<_Iter>()))
 __to_address(__wrap_iter<_Iter> __w) _NOEXCEPT {
     return _VSTD::__to_address(__w.base());
 }
diff --git a/libcxx/include/latch b/libcxx/include/latch
--- a/libcxx/include/latch
+++ b/libcxx/include/latch
@@ -40,8 +40,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <atomic>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/list b/libcxx/include/list
--- a/libcxx/include/list
+++ b/libcxx/include/list
@@ -181,17 +181,15 @@
 */
 
 #include <__config>
-
-#include <memory>
-#include <limits>
+#include <__debug>
+#include <algorithm>
 #include <initializer_list>
 #include <iterator>
-#include <algorithm>
+#include <limits>
+#include <memory>
 #include <type_traits>
 #include <version>
 
-#include <__debug>
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
diff --git a/libcxx/include/locale b/libcxx/include/locale
--- a/libcxx/include/locale
+++ b/libcxx/include/locale
@@ -188,21 +188,21 @@
 */
 
 #include <__config>
-#include <__locale>
 #include <__debug>
+#include <__locale>
 #include <algorithm>
-#include <memory>
-#include <ios>
-#include <streambuf>
-#include <iterator>
-#include <limits>
-#include <version>
 #ifndef __APPLE__
-#include <cstdarg>
+# include <cstdarg>
 #endif
+#include <cstdio>
 #include <cstdlib>
 #include <ctime>
-#include <cstdio>
+#include <ios>
+#include <iterator>
+#include <limits>
+#include <memory>
+#include <streambuf>
+#include <version>
 
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 // Most unix variants have catopen.  These are the specific ones that don't.
diff --git a/libcxx/include/map b/libcxx/include/map
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -490,13 +490,12 @@
 #include <__node_handle>
 #include <__tree>
 #include <compare>
+#include <functional>
 #include <initializer_list>
 #include <iterator> // __libcpp_erase_if_container
 #include <memory>
-#include <utility>
-#include <functional>
-#include <initializer_list>
 #include <type_traits>
+#include <utility>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/memory b/libcxx/include/memory
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -665,19 +665,7 @@
 */
 
 #include <__config>
-#include <type_traits>
-#include <typeinfo>
-#include <compare>
-#include <cstddef>
-#include <cstdint>
-#include <new>
-#include <utility>
-#include <iterator>
 #include <__functional_base>
-#include <iosfwd>
-#include <tuple>
-#include <stdexcept>
-#include <cstring>
 #include <__memory/addressof.h>
 #include <__memory/allocation_guard.h>
 #include <__memory/allocator.h>
@@ -691,6 +679,18 @@
 #include <__memory/temporary_buffer.h>
 #include <__memory/uninitialized_algorithms.h>
 #include <__memory/unique_ptr.h>
+#include <compare>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <iosfwd>
+#include <iterator>
+#include <new>
+#include <stdexcept>
+#include <tuple>
+#include <type_traits>
+#include <typeinfo>
+#include <utility>
 #include <version>
 
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -188,14 +188,14 @@
 
 #include <__config>
 #include <__mutex_base>
+#include <__threading_support>
 #include <cstdint>
 #include <functional>
 #include <memory>
 #ifndef _LIBCPP_CXX03_LANG
-#include <tuple>
+# include <tuple>
 #endif
 #include <version>
-#include <__threading_support>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/new b/libcxx/include/new
--- a/libcxx/include/new
+++ b/libcxx/include/new
@@ -86,8 +86,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <cstddef>
 #include <cstdlib>
 #include <exception>
diff --git a/libcxx/include/numbers b/libcxx/include/numbers
--- a/libcxx/include/numbers
+++ b/libcxx/include/numbers
@@ -59,13 +59,12 @@
 */
 
 #include <__config>
-
-#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
-
 #include <concepts>
 #include <type_traits>
 #include <version>
 
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
+
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
diff --git a/libcxx/include/optional b/libcxx/include/optional
--- a/libcxx/include/optional
+++ b/libcxx/include/optional
@@ -146,8 +146,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__debug>
 #include <__functional_base>
 #include <compare>
diff --git a/libcxx/include/ostream b/libcxx/include/ostream
--- a/libcxx/include/ostream
+++ b/libcxx/include/ostream
@@ -134,11 +134,11 @@
 */
 
 #include <__config>
+#include <bitset>
 #include <ios>
-#include <streambuf>
-#include <locale>
 #include <iterator>
-#include <bitset>
+#include <locale>
+#include <streambuf>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/queue b/libcxx/include/queue
--- a/libcxx/include/queue
+++ b/libcxx/include/queue
@@ -179,11 +179,11 @@
 */
 
 #include <__config>
+#include <algorithm>
 #include <compare>
 #include <deque>
-#include <vector>
 #include <functional>
-#include <algorithm>
+#include <vector>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/random b/libcxx/include/random
--- a/libcxx/include/random
+++ b/libcxx/include/random
@@ -1678,18 +1678,18 @@
 */
 
 #include <__config>
-#include <cstddef>
-#include <cstdint>
+#include <algorithm>
 #include <cmath>
 #include <concepts>
-#include <type_traits>
+#include <cstddef>
+#include <cstdint>
 #include <initializer_list>
+#include <iosfwd>
 #include <limits>
-#include <algorithm>
 #include <numeric>
-#include <vector>
 #include <string>
-#include <iosfwd>
+#include <type_traits>
+#include <vector>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -88,8 +88,8 @@
 #include <__ranges/data.h>
 #include <__ranges/empty.h>
 #include <__ranges/enable_borrowed_range.h>
-#include <__ranges/view.h>
 #include <__ranges/size.h>
+#include <__ranges/view.h>
 #include <compare>          // Required by the standard.
 #include <initializer_list> // Required by the standard.
 #include <iterator>         // Required by the standard.
diff --git a/libcxx/include/ratio b/libcxx/include/ratio
--- a/libcxx/include/ratio
+++ b/libcxx/include/ratio
@@ -78,8 +78,8 @@
 */
 
 #include <__config>
-#include <cstdint>
 #include <climits>
+#include <cstdint>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/semaphore b/libcxx/include/semaphore
--- a/libcxx/include/semaphore
+++ b/libcxx/include/semaphore
@@ -45,8 +45,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__threading_support>
 #include <atomic>
 
diff --git a/libcxx/include/shared_mutex b/libcxx/include/shared_mutex
--- a/libcxx/include/shared_mutex
+++ b/libcxx/include/shared_mutex
@@ -122,8 +122,8 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <version>
 
 _LIBCPP_PUSH_MACROS
diff --git a/libcxx/include/sstream b/libcxx/include/sstream
--- a/libcxx/include/sstream
+++ b/libcxx/include/sstream
@@ -181,8 +181,8 @@
 */
 
 #include <__config>
-#include <ostream>
 #include <istream>
+#include <ostream>
 #include <string>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/stdexcept b/libcxx/include/stdexcept
--- a/libcxx/include/stdexcept
+++ b/libcxx/include/stdexcept
@@ -42,9 +42,9 @@
 */
 
 #include <__config>
-#include <cstdlib>
 #include <exception>
 #include <iosfwd>  // for string forward decl
+#include <cstdlib>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/streambuf b/libcxx/include/streambuf
--- a/libcxx/include/streambuf
+++ b/libcxx/include/streambuf
@@ -108,8 +108,8 @@
 */
 
 #include <__config>
-#include <iosfwd>
 #include <ios>
+#include <iosfwd>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -514,27 +514,27 @@
 */
 
 #include <__config>
+#include <__debug>
+#include <__functional_base>
+#include <algorithm>
 #include <compare>
-#include <string_view>
-#include <iosfwd>
+#include <cstdio>  // EOF
 #include <cstring>
-#include <cstdio>  // For EOF.
 #include <cwchar>
-#include <algorithm>
+#include <initializer_list>
+#include <iosfwd>
 #include <iterator>
-#include <utility>
 #include <memory>
 #include <stdexcept>
+#include <string_view>
 #include <type_traits>
-#include <initializer_list>
-#include <__functional_base>
+#include <utility>
 #include <version>
+
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
-#include <cstdint>
+# include <cstdint>
 #endif
 
-#include <__debug>
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -182,16 +182,16 @@
 */
 
 #include <__config>
+#include <__debug>
 #include <__ranges/enable_borrowed_range.h>
 #include <__string>
-#include <iosfwd>
 #include <algorithm>
 #include <compare>
+#include <iosfwd>
 #include <iterator>
 #include <limits>
 #include <stdexcept>
 #include <version>
-#include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/strstream b/libcxx/include/strstream
--- a/libcxx/include/strstream
+++ b/libcxx/include/strstream
@@ -130,8 +130,8 @@
 */
 
 #include <__config>
-#include <ostream>
 #include <istream>
+#include <ostream>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/thread b/libcxx/include/thread
--- a/libcxx/include/thread
+++ b/libcxx/include/thread
@@ -83,20 +83,18 @@
 */
 
 #include <__config>
-#include <iosfwd>
+#include <__debug>
 #include <__functional_base>
-#include <type_traits>
+#include <__mutex_base>
+#include <__threading_support>
+#include <chrono>
 #include <cstddef>
 #include <functional>
+#include <iosfwd>
 #include <memory>
 #include <system_error>
-#include <chrono>
-#include <__mutex_base>
-#ifndef _LIBCPP_CXX03_LANG
 #include <tuple>
-#endif
-#include <__threading_support>
-#include <__debug>
+#include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -150,11 +150,11 @@
 */
 
 #include <__config>
+#include <__functional_base>
 #include <__tuple>
 #include <compare>
 #include <cstddef>
 #include <type_traits>
-#include <__functional_base>
 #include <utility>
 #include <version>
 
diff --git a/libcxx/include/typeindex b/libcxx/include/typeindex
--- a/libcxx/include/typeindex
+++ b/libcxx/include/typeindex
@@ -45,9 +45,9 @@
 */
 
 #include <__config>
-#include <typeinfo>
 #include <__functional_base>
 #include <compare>
+#include <typeinfo>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/typeinfo b/libcxx/include/typeinfo
--- a/libcxx/include/typeinfo
+++ b/libcxx/include/typeinfo
@@ -56,12 +56,13 @@
 
 */
 
-#include <__config>
 #include <__availability>
-#include <exception>
+#include <__config>
 #include <cstddef>
 #include <cstdint>
+#include <exception>
 #include <type_traits>
+
 #ifdef _LIBCPP_NO_EXCEPTIONS
 #include <cstdlib>
 #endif
diff --git a/libcxx/include/unordered_map b/libcxx/include/unordered_map
--- a/libcxx/include/unordered_map
+++ b/libcxx/include/unordered_map
@@ -432,6 +432,7 @@
 */
 
 #include <__config>
+#include <__debug>
 #include <__hash_table>
 #include <__node_handle>
 #include <compare>
@@ -441,8 +442,6 @@
 #include <tuple>
 #include <version>
 
-#include <__debug>
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
diff --git a/libcxx/include/unordered_set b/libcxx/include/unordered_set
--- a/libcxx/include/unordered_set
+++ b/libcxx/include/unordered_set
@@ -387,6 +387,7 @@
 */
 
 #include <__config>
+#include <__debug>
 #include <__hash_table>
 #include <__node_handle>
 #include <compare>
@@ -394,8 +395,6 @@
 #include <iterator> // __libcpp_erase_if_container
 #include <version>
 
-#include <__debug>
-
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
diff --git a/libcxx/include/utility b/libcxx/include/utility
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -208,17 +208,17 @@
 */
 
 #include <__config>
+#include <__debug>
 #include <__tuple>
 #include <__utility/to_underlying.h>
 #include <compare>
-#include <type_traits>
-#include <initializer_list>
 #include <cstddef>
-#include <cstring>
 #include <cstdint>
+#include <cstring>
+#include <initializer_list>
 #include <limits>
+#include <type_traits>
 #include <version>
-#include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/include/valarray b/libcxx/include/valarray
--- a/libcxx/include/valarray
+++ b/libcxx/include/valarray
@@ -340,11 +340,11 @@
 */
 
 #include <__config>
-#include <cstddef>
-#include <cmath>
-#include <initializer_list>
 #include <algorithm>
+#include <cmath>
+#include <cstddef>
 #include <functional>
+#include <initializer_list>
 #include <new>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -354,7 +354,6 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template<class _Tp> class _LIBCPP_TEMPLATE_VIS valarray;
diff --git a/libcxx/include/variant b/libcxx/include/variant
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -199,19 +199,19 @@
 
 */
 
-#include <__config>
 #include <__availability>
+#include <__config>
 #include <__tuple>
 #include <array>
 #include <compare>
 #include <exception>
 #include <functional>
 #include <initializer_list>
+#include <limits>
 #include <new>
 #include <tuple>
 #include <type_traits>
 #include <utility>
-#include <limits>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/vector b/libcxx/include/vector
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -272,22 +272,21 @@
 */
 
 #include <__config>
-#include <iosfwd> // for forward declaration of vector
 #include <__bit_reference>
-#include <type_traits>
+#include <__debug>
+#include <__functional_base>
+#include <__split_buffer>
+#include <algorithm>
 #include <climits>
 #include <compare>
-#include <limits>
+#include <cstring>
 #include <initializer_list>
+#include <iosfwd> // for forward declaration of vector
+#include <limits>
 #include <memory>
 #include <stdexcept>
-#include <algorithm>
-#include <cstring>
+#include <type_traits>
 #include <version>
-#include <__split_buffer>
-#include <__functional_base>
-
-#include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
diff --git a/libcxx/test/libcxx/iterators/contiguous_iterators.pass.cpp b/libcxx/test/libcxx/iterators/contiguous_iterators.pass.cpp
--- a/libcxx/test/libcxx/iterators/contiguous_iterators.pass.cpp
+++ b/libcxx/test/libcxx/iterators/contiguous_iterators.pass.cpp
@@ -138,6 +138,21 @@
 };
 #endif
 
+struct fake_deque_iterator : std::deque<int>::iterator {
+    using element_type = int;
+};
+static_assert(std::__is_cpp17_random_access_iterator<fake_deque_iterator>::value, "");
+static_assert(!std::__is_cpp17_contiguous_iterator<fake_deque_iterator>::value, "");
+
+#if TEST_STD_VER >= 20
+struct fake2_deque_iterator : std::deque<int>::iterator {
+    using iterator_concept = std::contiguous_iterator_tag;
+    using element_type = int;
+};
+static_assert(std::__is_cpp17_random_access_iterator<fake2_deque_iterator>::value, "");
+static_assert(std::__is_cpp17_contiguous_iterator<fake2_deque_iterator>::value, "");
+#endif
+
 int main(int, char**)
 {
 //  basic tests
@@ -178,21 +193,19 @@
 
     static_assert(( std::__is_cpp17_contiguous_iterator<std::__wrap_iter<T *> >::value), "");
     static_assert(( std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::__wrap_iter<T *> > >::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::reverse_iterator<T *> > >::value), "");
 
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<my_random_access_iterator> >::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::__wrap_iter<my_random_access_iterator> > >::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::reverse_iterator<my_random_access_iterator> > >::value), "");
+    // Here my_random_access_iterator is standing in for some user's fancy pointer type, written pre-C++20.
+    static_assert(( std::__is_cpp17_contiguous_iterator<std::__wrap_iter<my_random_access_iterator> >::value), "");
+    static_assert(( std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::__wrap_iter<my_random_access_iterator> > >::value), "");
 
 #if TEST_STD_VER >= 20
     static_assert(( std::__is_cpp17_contiguous_iterator<std::__wrap_iter<my_contiguous_iterator> >::value), "");
     static_assert(( std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::__wrap_iter<my_contiguous_iterator> > >::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::reverse_iterator<my_contiguous_iterator> > >::value), "");
 #endif
 
 //  iterators in the libc++ test suite
     static_assert((!std::__is_cpp17_contiguous_iterator<output_iterator       <char *> >::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<cpp17_input_iterator        <char *> >::value), "");
+    static_assert((!std::__is_cpp17_contiguous_iterator<cpp17_input_iterator  <char *> >::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<forward_iterator      <char *> >::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<bidirectional_iterator<char *> >::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<random_access_iterator<char *> >::value), "");
@@ -228,14 +241,12 @@
     static_assert((!std::__is_cpp17_contiguous_iterator<std::deque<int>::const_iterator>             ::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<std::deque<int>::reverse_iterator>           ::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<std::deque<int>::const_reverse_iterator>     ::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::deque<int>::iterator> >::value), "");
 
 //  vector<bool> is random-access but not contiguous
     static_assert((!std::__is_cpp17_contiguous_iterator<std::vector<bool>::iterator>                   ::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<std::vector<bool>::const_iterator>             ::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<std::vector<bool>::reverse_iterator>           ::value), "");
     static_assert((!std::__is_cpp17_contiguous_iterator<std::vector<bool>::const_reverse_iterator>     ::value), "");
-    static_assert((!std::__is_cpp17_contiguous_iterator<std::__wrap_iter<std::vector<bool>::iterator> >::value), "");
 
 #if TEST_STD_VER >= 11
     static_assert(( std::__is_cpp17_contiguous_iterator<std::initializer_list<int>::iterator>      ::value), "");