[libcxx][gardening] Move all algorithms into their own headers.

[ldionne]

Summary

This is a fairly mechanical change, it just moves each algorithm into its own header. This is a NFC.

Note: during this change, I burned down all the includes, so this follows "include only and exactly what you use."

There may be some module work that needs to happen here. Let's see what the CI thinks.

[zoecarver]

Note: this change includes D103330. I just subsumed that patch because I need to use some things form it and update it a bit. I think it's easiest to just take this one rather than trying to deal with merge conflicts and updates to that one.

[zoecarver]

Remove two unrelated files.

[cjdb]

libcxx/include/module.modulemap

220–223

You'll need to replicate what I do in D103551 for every algorithm header.

395–396

437–440

Delete.

537–540

Delete.

[• Quuxplusone]

Not a blocker, but just for curiosity's sake, could you run graph_header_deps.py before and after this patch and upload the images somewhere?
libcxx/utils/graph_header_deps.py | dot -Tpng > coolgraph.png
We expect the graph to get vastly more dotty-and-liney, but maybe less bottlenecky? It'd be interesting to look at, anyway.

[ldionne]

This LGTM, however I want to understand the recent Modules failures better before checking this in, to make sure we don't have to revert it. It has the potential to be fairly disruptive (in terms of downstream merge conflicts for people with forks and stuff like that). I just want to make sure that we get it right the first time around, so please hold on with committing until we've made sure of that.

[cjdb]

Note: during this change, I burned down all the includes, so this follows "include only and exactly what you use."

In D103330 @ldionne asked that this be done in a separate patch.

[• Quuxplusone]

libcxx/include/algorithm

648–665

(A) Why are these few headers alphabetized and then the bulk of them (below) done... below?

(B) @cjdb wrote:

Note: during this change, I burned down all the includes, so this follows "include only and exactly what you use."

In D103330 @ldionne asked that this be done in a separate patch.

The important thing @ldionne was getting at in D103330 is Hyrum's Law. We need to make sure that we don't break any of libc++'s customers who might be relying on the fact e.g. "by including <algorithm>, I also receive all of <functional>." @zoecarver's change doesn't actually affect those customers AFAICT, because he's leaving the existing includes alone here (e.g. <algorithm> does still include <functional>).

However, @zoecarver, please do triple-check this PR to make sure that the top-level <algorithm> header still includes all the facilities it used to, and that the same is true for all other top-level publicly visible headers (e.g. <functional>, <iterator>, anything else that might have changed).

[zoecarver]

• Modularize

[zoecarver]

libcxx/include/algorithm

648–665

(A) Why are these few headers alphabetized and then the bulk of them (below) done... below?

Arg. Sorry this came out of merging Chris' patch with mine. Will fix. (Come to think of it, I also need to update the cmake list.)

The important thing @ldionne was getting at in D103330 is Hyrum's Law. We need to make sure that we don't break any of libc++'s customers who might be relying on the fact e.g. "by including <algorithm>, I also receive all of <functional>." @zoecarver's change doesn't actually affect those customers AFAICT, because he's leaving the existing includes alone here (e.g. <algorithm> does still include <functional>).

However, @zoecarver, please do triple-check this PR to make sure that the top-level <algorithm> header still includes all the facilities it used to, and that the same is true for all other top-level publicly visible headers (e.g. <functional>, <iterator>, anything else that might have changed).

Yes. I haven't removed anything from <algorithm>.

[zoecarver]

• Re-alphabatize and add a few missing modules to the module map
• __search.h -> search.h

[zoecarver]

• Remove two unrealted files

[cjdb]

LGTM pending my requested deletions.

libcxx/include/module.modulemap

292–294

Delete

[zoecarver]

Rebase.

[zoecarver]

Add back half_positive.h which got removed on accident (and I didn't catch it because cmake cached it in the build directoyr).

[zoecarver]

Fix another include issue that I didn't catch thanks to ninja caching.

[• Quuxplusone]

Double-check your module.modulemap changes: I still see at least one export * in there.
Also some removed blank lines that may or may not have been on purpose. Just make sure the style we end up with is consistent across all the sections of module.modulemap.
Otherwise, sure, LGTM (modulo my usual curmudgeoning that all these little headers are gonna be icky).

Also: I assume it's intentional that you went with half_positive.h instead of __half_positive.h, and so on? (I.e., some of these files define standard algorithms and some define helpers, with no clear naming distinction between the two kinds.)

[cjdb]

In D103583#2797366, @Quuxplusone wrote:

Also: I assume it's intentional that you went with half_positive.h instead of __half_positive.h, and so on? (I.e., some of these files define standard algorithms and some define helpers, with no clear naming distinction between the two kinds.)

Agreed that we should probably get a convention going. We can do that offline, but I've been following whatever is the salient feature of the file. If it's __half_positive, then I'd make the header __half_positive.h.

libcxx/include/module.modulemap

295

This export * still needs to go.

[ldionne]

Commandeering as I'm getting ready to re-apply this change (well, really D104171 which is a mix of D103330, this and additional work).

[ldionne]

Update to https://reviews.llvm.org/D104171.

[ldionne]

@phosek Could you please apply this change locally and run whatever you ran that caused you to revert last week? I think we should have fixed our stuff, but I really want to make sure we're not going to break you again, because it's extremely painful for us to revert and re-apply such a large change (and it messes up the history pretty badly, too).

[phosek]

LGTM

libcxx/include/CMakeLists.txt

 set(files
+  __algorithm/adjacent_find.h
+  __algorithm/all_of.h
+  __algorithm/any_of.h
+  __algorithm/binary_search.h
+  __algorithm/clamp.h
+  __algorithm/comp.h
+  __algorithm/comp_ref_type.h
+  __algorithm/copy.h
+  __algorithm/count.h
+  __algorithm/count_if.h
+  __algorithm/equal.h
+  __algorithm/equal_range.h
+  __algorithm/fill.h
+  __algorithm/find.h
+  __algorithm/find_end.h
+  __algorithm/find_first_of.h
+  __algorithm/find_if.h
+  __algorithm/find_if_not.h
+  __algorithm/for_each.h
+  __algorithm/for_each_n.h
+  __algorithm/generate.h
+  __algorithm/half_positive.h
+  __algorithm/includes.h
+  __algorithm/inplace_merge.h
+  __algorithm/is_heap.h
+  __algorithm/is_heap_until.h
+  __algorithm/is_partitioned.h
+  __algorithm/is_permutation.h
+  __algorithm/is_sorted.h
+  __algorithm/lexicographical_compare.h
+  __algorithm/lower_bound.h
+  __algorithm/make_heap.h
+  __algorithm/max.h
+  __algorithm/max_element.h
+  __algorithm/merge.h
+  __algorithm/min.h
+  __algorithm/min_element.h
+  __algorithm/minmax.h
+  __algorithm/minmax_element.h
+  __algorithm/mismatch.h
+  __algorithm/move.h
+  __algorithm/next_permutation.h
+  __algorithm/none_of.h
+  __algorithm/nth_element.h
+  __algorithm/partial_sort.h
+  __algorithm/partition.h
+  __algorithm/partition_point.h
+  __algorithm/pop_heap.h
+  __algorithm/prev_permutation.h
+  __algorithm/push_heap.h
+  __algorithm/remove.h
+  __algorithm/replace.h
+  __algorithm/reverse.h
+  __algorithm/rotate.h
+  __algorithm/sample.h
+  __algorithm/search.h
+  __algorithm/search_n.h
+  __algorithm/set_difference.h
+  __algorithm/set_intersection.h
+  __algorithm/set_symmetric_difference.h
+  __algorithm/set_union.h
+  __algorithm/shift.h
+  __algorithm/shuffle.h
+  __algorithm/sift_down.h
+  __algorithm/sort.h
+  __algorithm/sort_heap.h
+  __algorithm/stable_partition.h
+  __algorithm/stable_sort.h
+  __algorithm/transform.h
+  __algorithm/uniform_int_distribution.h
+  __algorithm/unique.h
+  __algorithm/unwrap_iter.h
+  __algorithm/upper_bound.h
   __availability
   __bit_reference
   __bits
   __bsd_locale_defaults.h
   __bsd_locale_fallbacks.h
   __config
   __debug
   __errc
   __format/format_error.h
   __format/format_parse_context.h
   __function_like.h
+  __functional/search.h
   __functional_03
   __functional_base
   __functional_base_03
   __hash_table
   __iterator/advance.h
   __iterator/concepts.h
   __iterator/default_sentinel.h
   __iterator/incrementable_traits.h

libcxx/include/__algorithm/adjacent_find.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_ADJACENT_FIND_H
+#define _LIBCPP___ALGORITHM_ADJACENT_FIND_H
+
+#include <__config>
+#include <__algorithm/comp.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred) {
+  if (__first != __last) {
+    _ForwardIterator __i = __first;
+    while (++__i != __last) {
+      if (__pred(*__first, *__i))
+        return __first;
+      __first = __i;
+    }
+  }
+  return __last;
+}
+
+template <class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+adjacent_find(_ForwardIterator __first, _ForwardIterator __last) {
+  typedef typename iterator_traits<_ForwardIterator>::value_type __v;
+  return _VSTD::adjacent_find(__first, __last, __equal_to<__v>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_ADJACENT_FIND_H

libcxx/include/__algorithm/all_of.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_ALL_OF_H
+#define _LIBCPP___ALGORITHM_ALL_OF_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
+  for (; __first != __last; ++__first)
+    if (!__pred(*__first))
+      return false;
+  return true;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_ALL_OF_H

libcxx/include/__algorithm/any_of.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_ANY_OF_H
+#define _LIBCPP___ALGORITHM_ANY_OF_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
+  for (; __first != __last; ++__first)
+    if (__pred(*__first))
+      return true;
+  return false;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_ANY_OF_H

libcxx/include/__algorithm/binary_search.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_BINARY_SEARCH_H
+#define _LIBCPP___ALGORITHM_BINARY_SEARCH_H
+
+#include <__config>
+#include <__algorithm/lower_bound.h>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _ForwardIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+__binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    __first = _VSTD::__lower_bound<_Compare>(__first, __last, __value_, __comp);
+    return __first != __last && !__comp(__value_, *__first);
+}
+
+template <class _ForwardIterator, class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__binary_search<_Comp_ref>(__first, __last, __value_, __comp);
+}
+
+template <class _ForwardIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
+{
+    return _VSTD::binary_search(__first, __last, __value_,
+                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
+}
+
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_BINARY_SEARCH_H

libcxx/include/__algorithm/clamp.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_CLAMP_H
+#define _LIBCPP___ALGORITHM_CLAMP_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 14
+// clamp
+template<class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+const _Tp&
+clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi, _Compare __comp)
+{
+    _LIBCPP_ASSERT(!__comp(__hi, __lo), "Bad bounds passed to std::clamp");
+    return __comp(__v, __lo) ? __lo : __comp(__hi, __v) ? __hi : __v;
+
+}
+
+template<class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+const _Tp&
+clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi)
+{
+    return _VSTD::clamp(__v, __lo, __hi, __less<_Tp>());
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_CLAMP_H

libcxx/include/__algorithm/comp.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_COMP_H
+#define _LIBCPP___ALGORITHM_COMP_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// I'd like to replace these with _VSTD::equal_to<void>, but can't because:
+//   * That only works with C++14 and later, and
+//   * We haven't included <functional> here.
+template <class _T1, class _T2 = _T1>
+struct __equal_to
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T2& __y) const {return __x == __y;}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T1& __y) const {return __x == __y;}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T2& __y) const {return __x == __y;}
+};
+
+template <class _T1>
+struct __equal_to<_T1, _T1>
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+};
+
+template <class _T1>
+struct __equal_to<const _T1, _T1>
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+};
+
+template <class _T1>
+struct __equal_to<_T1, const _T1>
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+};
+
+template <class _T1, class _T2 = _T1>
+struct __less
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
+};
+
+template <class _T1>
+struct __less<_T1, _T1>
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+};
+
+template <class _T1>
+struct __less<const _T1, _T1>
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+};
+
+template <class _T1>
+struct __less<_T1, const _T1>
+{
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_COMP_H

libcxx/include/__algorithm/comp_ref_type.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_COMP_REF_TYPE_H
+#define _LIBCPP___ALGORITHM_COMP_REF_TYPE_H
+
+#include <__config>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef _LIBCPP_DEBUG
+
+template <class _Compare>
+struct __debug_less
+{
+    _Compare &__comp_;
+    _LIBCPP_CONSTEXPR_AFTER_CXX17
+    __debug_less(_Compare& __c) : __comp_(__c) {}
+
+    template <class _Tp, class _Up>
+    _LIBCPP_CONSTEXPR_AFTER_CXX17
+    bool operator()(const _Tp& __x,  const _Up& __y)
+    {
+        bool __r = __comp_(__x, __y);
+        if (__r)
+            __do_compare_assert(0, __y, __x);
+        return __r;
+    }
+
+    template <class _Tp, class _Up>
+    _LIBCPP_CONSTEXPR_AFTER_CXX17
+    bool operator()(_Tp& __x,  _Up& __y)
+    {
+        bool __r = __comp_(__x, __y);
+        if (__r)
+            __do_compare_assert(0, __y, __x);
+        return __r;
+    }
+
+    template <class _LHS, class _RHS>
+    _LIBCPP_CONSTEXPR_AFTER_CXX17
+    inline _LIBCPP_INLINE_VISIBILITY
+    decltype((void)declval<_Compare&>()(
+        declval<_LHS &>(), declval<_RHS &>()))
+    __do_compare_assert(int, _LHS & __l, _RHS & __r) {
+        _LIBCPP_ASSERT(!__comp_(__l, __r),
+            "Comparator does not induce a strict weak ordering");
+    }
+
+    template <class _LHS, class _RHS>
+    _LIBCPP_CONSTEXPR_AFTER_CXX17
+    inline _LIBCPP_INLINE_VISIBILITY
+    void __do_compare_assert(long, _LHS &, _RHS &) {}
+};
+
+#endif // _LIBCPP_DEBUG
+
+template <class _Comp>
+struct __comp_ref_type {
+  // Pass the comparator by lvalue reference. Or in debug mode, using a
+  // debugging wrapper that stores a reference.
+#ifndef _LIBCPP_DEBUG
+  typedef typename add_lvalue_reference<_Comp>::type type;
+#else
+  typedef __debug_less<_Comp> type;
+#endif
+};
+
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_COMP_REF_TYPE_H

libcxx/include/__algorithm/copy.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_COPY_H
+#define _LIBCPP___ALGORITHM_COPY_H
+
+#include <__config>
+#include <__algorithm/unwrap_iter.h>
+#include <__iterator/iterator_traits.h>
+#include <cstring>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// copy
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+__copy_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    for (; __first != __last; ++__first, (void) ++__result)
+        *__result = *__first;
+    return __result;
+}
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+_OutputIterator
+__copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    return _VSTD::__copy_constexpr(__first, __last, __result);
+}
+
+template <class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_same<typename remove_const<_Tp>::type, _Up>::value &&
+    is_trivially_copy_assignable<_Up>::value,
+    _Up*
+>::type
+__copy(_Tp* __first, _Tp* __last, _Up* __result)
+{
+    const size_t __n = static_cast<size_t>(__last - __first);
+    if (__n > 0)
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    return __result + __n;
+}
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    if (__libcpp_is_constant_evaluated()) {
+        return _VSTD::__copy_constexpr(__first, __last, __result);
+    } else {
+        return _VSTD::__rewrap_iter(__result,
+            _VSTD::__copy(_VSTD::__unwrap_iter(__first),
+                          _VSTD::__unwrap_iter(__last),
+                          _VSTD::__unwrap_iter(__result)));
+    }
+}
+
+// copy_backward
+
+template <class _BidirectionalIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+__copy_backward_constexpr(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
+{
+    while (__first != __last)
+        *--__result = *--__last;
+    return __result;
+}
+
+template <class _BidirectionalIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+_OutputIterator
+__copy_backward(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
+{
+    return _VSTD::__copy_backward_constexpr(__first, __last, __result);
+}
+
+template <class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    is_same<typename remove_const<_Tp>::type, _Up>::value &&
+    is_trivially_copy_assignable<_Up>::value,
+    _Up*
+>::type
+__copy_backward(_Tp* __first, _Tp* __last, _Up* __result)
+{
+    const size_t __n = static_cast<size_t>(__last - __first);
+    if (__n > 0)
+    {
+        __result -= __n;
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    }
+    return __result;
+}
+
+template <class _BidirectionalIterator1, class _BidirectionalIterator2>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_BidirectionalIterator2
+copy_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
+              _BidirectionalIterator2 __result)
+{
+    if (__libcpp_is_constant_evaluated()) {
+        return _VSTD::__copy_backward_constexpr(__first, __last, __result);
+    } else {
+        return _VSTD::__rewrap_iter(__result,
+            _VSTD::__copy_backward(_VSTD::__unwrap_iter(__first),
+                                   _VSTD::__unwrap_iter(__last),
+                                   _VSTD::__unwrap_iter(__result)));
+    }
+}
+
+// copy_if
+
+template<class _InputIterator, class _OutputIterator, class _Predicate>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+copy_if(_InputIterator __first, _InputIterator __last,
+        _OutputIterator __result, _Predicate __pred)
+{
+    for (; __first != __last; ++__first)
+    {
+        if (__pred(*__first))
+        {
+            *__result = *__first;
+            ++__result;
+        }
+    }
+    return __result;
+}
+
+// copy_n
+
+template<class _InputIterator, class _Size, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+typename enable_if
+<
+    __is_cpp17_input_iterator<_InputIterator>::value &&
+   !__is_cpp17_random_access_iterator<_InputIterator>::value,
+    _OutputIterator
+>::type
+copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
+{
+    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
+    _IntegralSize __n = __orig_n;
+    if (__n > 0)
+    {
+        *__result = *__first;
+        ++__result;
+        for (--__n; __n > 0; --__n)
+        {
+            ++__first;
+            *__result = *__first;
+            ++__result;
+        }
+    }
+    return __result;
+}
+
+template<class _InputIterator, class _Size, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+typename enable_if
+<
+    __is_cpp17_random_access_iterator<_InputIterator>::value,
+    _OutputIterator
+>::type
+copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
+{
+    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
+    _IntegralSize __n = __orig_n;
+    return _VSTD::copy(__first, __first + __n, __result);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_COPY_H

libcxx/include/__algorithm/count.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_COUNT_H
+#define _LIBCPP___ALGORITHM_COUNT_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    typename iterator_traits<_InputIterator>::difference_type
+    count(_InputIterator __first, _InputIterator __last, const _Tp& __value_) {
+  typename iterator_traits<_InputIterator>::difference_type __r(0);
+  for (; __first != __last; ++__first)
+    if (*__first == __value_)
+      ++__r;
+  return __r;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_COUNT_H

libcxx/include/__algorithm/count_if.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_COUNT_IF_H
+#define _LIBCPP___ALGORITHM_COUNT_IF_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    typename iterator_traits<_InputIterator>::difference_type
+    count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
+  typename iterator_traits<_InputIterator>::difference_type __r(0);
+  for (; __first != __last; ++__first)
+    if (__pred(*__first))
+      ++__r;
+  return __r;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_COUNT_IF_H

libcxx/include/__algorithm/equal.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_EQUAL_H
+#define _LIBCPP___ALGORITHM_EQUAL_H
+
+#include <__config>
+#include <__algorithm/comp.h>
+#include <__iterator/iterator_traits.h>
+#include <iterator> // FIXME: replace with <__iterator/distance.h> when it lands
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred) {
+  for (; __first1 != __last1; ++__first1, (void)++__first2)
+    if (!__pred(*__first1, *__first2))
+      return false;
+  return true;
+}
+
+template <class _InputIterator1, class _InputIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2) {
+  typedef typename iterator_traits<_InputIterator1>::value_type __v1;
+  typedef typename iterator_traits<_InputIterator2>::value_type __v2;
+  return _VSTD::equal(__first1, __last1, __first2, __equal_to<__v1, __v2>());
+}
+
+#if _LIBCPP_STD_VER > 11
+template <class _BinaryPredicate, class _InputIterator1, class _InputIterator2>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
+        _BinaryPredicate __pred, input_iterator_tag, input_iterator_tag) {
+  for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void)++__first2)
+    if (!__pred(*__first1, *__first2))
+      return false;
+  return __first1 == __last1 && __first2 == __last2;
+}
+
+template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
+        _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag,
+        random_access_iterator_tag) {
+  if (_VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
+    return false;
+  return _VSTD::equal<_RandomAccessIterator1, _RandomAccessIterator2,
+                      typename add_lvalue_reference<_BinaryPredicate>::type>(__first1, __last1, __first2, __pred);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
+      _BinaryPredicate __pred) {
+  return _VSTD::__equal<typename add_lvalue_reference<_BinaryPredicate>::type>(
+      __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_InputIterator1>::iterator_category(),
+      typename iterator_traits<_InputIterator2>::iterator_category());
+}
+
+template <class _InputIterator1, class _InputIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2) {
+  typedef typename iterator_traits<_InputIterator1>::value_type __v1;
+  typedef typename iterator_traits<_InputIterator2>::value_type __v2;
+  return _VSTD::__equal(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(),
+                        typename iterator_traits<_InputIterator1>::iterator_category(),
+                        typename iterator_traits<_InputIterator2>::iterator_category());
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_EQUAL_H

libcxx/include/__algorithm/equal_range.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_EQUAL_RANGE_H
+#define _LIBCPP___ALGORITHM_EQUAL_RANGE_H
+
+#include <__config>
+#include <__algorithm/lower_bound.h>
+#include <__algorithm/upper_bound.h>
+#include <__algorithm/comp_ref_type.h>
+#include <iterator>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _ForwardIterator, class _Tp>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
+__equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
+    difference_type __len = _VSTD::distance(__first, __last);
+    while (__len != 0)
+    {
+        difference_type __l2 = _VSTD::__half_positive(__len);
+        _ForwardIterator __m = __first;
+        _VSTD::advance(__m, __l2);
+        if (__comp(*__m, __value_))
+        {
+            __first = ++__m;
+            __len -= __l2 + 1;
+        }
+        else if (__comp(__value_, *__m))
+        {
+            __last = __m;
+            __len = __l2;
+        }
+        else
+        {
+            _ForwardIterator __mp1 = __m;
+            return pair<_ForwardIterator, _ForwardIterator>
+                   (
+                      _VSTD::__lower_bound<_Compare>(__first, __m, __value_, __comp),
+                      _VSTD::__upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
+                   );
+        }
+    }
+    return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
+}
+
+template <class _ForwardIterator, class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+pair<_ForwardIterator, _ForwardIterator>
+equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__equal_range<_Comp_ref>(__first, __last, __value_, __comp);
+}
+
+template <class _ForwardIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+pair<_ForwardIterator, _ForwardIterator>
+equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
+{
+    return _VSTD::equal_range(__first, __last, __value_,
+                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_EQUAL_RANGE_H

libcxx/include/__algorithm/fill.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FILL_H
+#define _LIBCPP___ALGORITHM_FILL_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// fill_n
+
+template <class _OutputIterator, class _Size, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+__fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
+{
+    for (; __n > 0; ++__first, (void) --__n)
+        *__first = __value_;
+    return __first;
+}
+
+template <class _OutputIterator, class _Size, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
+{
+   return _VSTD::__fill_n(__first, _VSTD::__convert_to_integral(__n), __value_);
+}
+
+// fill
+
+template <class _ForwardIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, forward_iterator_tag)
+{
+    for (; __first != __last; ++__first)
+        *__first = __value_;
+}
+
+template <class _RandomAccessIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value_, random_access_iterator_tag)
+{
+    _VSTD::fill_n(__first, __last - __first, __value_);
+}
+
+template <class _ForwardIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
+{
+    _VSTD::__fill(__first, __last, __value_, typename iterator_traits<_ForwardIterator>::iterator_category());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FILL_H

libcxx/include/__algorithm/find.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FIND_H
+#define _LIBCPP___ALGORITHM_FIND_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _InputIterator
+find(_InputIterator __first, _InputIterator __last, const _Tp& __value_) {
+  for (; __first != __last; ++__first)
+    if (*__first == __value_)
+      break;
+  return __first;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FIND_H

libcxx/include/__algorithm/find_end.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FIND_END_OF_H
+#define _LIBCPP___ALGORITHM_FIND_END_OF_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
+                                                           _ForwardIterator2 __first2, _ForwardIterator2 __last2,
+                                                           _BinaryPredicate __pred, forward_iterator_tag,
+                                                           forward_iterator_tag) {
+  // modeled after search algorithm
+  _ForwardIterator1 __r = __last1; // __last1 is the "default" answer
+  if (__first2 == __last2)
+    return __r;
+  while (true) {
+    while (true) {
+      if (__first1 == __last1) // if source exhausted return last correct answer
+        return __r;            //    (or __last1 if never found)
+      if (__pred(*__first1, *__first2))
+        break;
+      ++__first1;
+    }
+    // *__first1 matches *__first2, now match elements after here
+    _ForwardIterator1 __m1 = __first1;
+    _ForwardIterator2 __m2 = __first2;
+    while (true) {
+      if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one
+        __r = __first1;
+        ++__first1;
+        break;
+      }
+      if (++__m1 == __last1) // Source exhausted, return last answer
+        return __r;
+      if (!__pred(*__m1, *__m2)) // mismatch, restart with a new __first
+      {
+        ++__first1;
+        break;
+      } // else there is a match, check next elements
+    }
+  }
+}
+
+template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1 __find_end(
+    _BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1, _BidirectionalIterator2 __first2,
+    _BidirectionalIterator2 __last2, _BinaryPredicate __pred, bidirectional_iterator_tag, bidirectional_iterator_tag) {
+  // modeled after search algorithm (in reverse)
+  if (__first2 == __last2)
+    return __last1; // Everything matches an empty sequence
+  _BidirectionalIterator1 __l1 = __last1;
+  _BidirectionalIterator2 __l2 = __last2;
+  --__l2;
+  while (true) {
+    // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
+    while (true) {
+      if (__first1 == __l1) // return __last1 if no element matches *__first2
+        return __last1;
+      if (__pred(*--__l1, *__l2))
+        break;
+    }
+    // *__l1 matches *__l2, now match elements before here
+    _BidirectionalIterator1 __m1 = __l1;
+    _BidirectionalIterator2 __m2 = __l2;
+    while (true) {
+      if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
+        return __m1;
+      if (__m1 == __first1) // Otherwise if source exhaused, pattern not found
+        return __last1;
+      if (!__pred(*--__m1, *--__m2)) // if there is a mismatch, restart with a new __l1
+      {
+        break;
+      } // else there is a match, check next elements
+    }
+  }
+}
+
+template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1 __find_end(
+    _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
+    _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag, random_access_iterator_tag) {
+  // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
+  typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2;
+  if (__len2 == 0)
+    return __last1;
+  typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1;
+  if (__len1 < __len2)
+    return __last1;
+  const _RandomAccessIterator1 __s = __first1 + (__len2 - 1); // End of pattern match can't go before here
+  _RandomAccessIterator1 __l1 = __last1;
+  _RandomAccessIterator2 __l2 = __last2;
+  --__l2;
+  while (true) {
+    while (true) {
+      if (__s == __l1)
+        return __last1;
+      if (__pred(*--__l1, *__l2))
+        break;
+    }
+    _RandomAccessIterator1 __m1 = __l1;
+    _RandomAccessIterator2 __m2 = __l2;
+    while (true) {
+      if (__m2 == __first2)
+        return __m1;
+      // no need to check range on __m1 because __s guarantees we have enough source
+      if (!__pred(*--__m1, *--__m2)) {
+        break;
+      }
+    }
+  }
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
+find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2,
+         _BinaryPredicate __pred) {
+  return _VSTD::__find_end<typename add_lvalue_reference<_BinaryPredicate>::type>(
+      __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(),
+      typename iterator_traits<_ForwardIterator2>::iterator_category());
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
+find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
+  typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
+  typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
+  return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FIND_END_OF_H

libcxx/include/__algorithm/find_first_of.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FIND_FIRST_OF_H
+#define _LIBCPP___ALGORITHM_FIND_FIRST_OF_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator1 __find_first_of_ce(_ForwardIterator1 __first1,
+                                                                   _ForwardIterator1 __last1,
+                                                                   _ForwardIterator2 __first2,
+                                                                   _ForwardIterator2 __last2, _BinaryPredicate __pred) {
+  for (; __first1 != __last1; ++__first1)
+    for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
+      if (__pred(*__first1, *__j))
+        return __first1;
+  return __last1;
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
+find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
+              _ForwardIterator2 __last2, _BinaryPredicate __pred) {
+  return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __pred);
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 find_first_of(
+    _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
+  typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
+  typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
+  return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FIND_FIRST_OF_H

libcxx/include/__algorithm/find_if.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FIND_IF_H
+#define _LIBCPP___ALGORITHM_FIND_IF_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _InputIterator
+find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
+  for (; __first != __last; ++__first)
+    if (__pred(*__first))
+      break;
+  return __first;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FIND_IF_H

libcxx/include/__algorithm/find_if_not.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FIND_IF_NOT_H
+#define _LIBCPP___ALGORITHM_FIND_IF_NOT_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _InputIterator
+find_if_not(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
+  for (; __first != __last; ++__first)
+    if (!__pred(*__first))
+      break;
+  return __first;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FIND_IF_NOT_H

libcxx/include/__algorithm/for_each.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FOR_EACH_H
+#define _LIBCPP___ALGORITHM_FOR_EACH_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Function>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _Function for_each(_InputIterator __first,
+                                                                                  _InputIterator __last,
+                                                                                  _Function __f) {
+  for (; __first != __last; ++__first)
+    __f(*__first);
+  return __f;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FOR_EACH_H

libcxx/include/__algorithm/for_each_n.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FOR_EACH_N_H
+#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
+
+#include <__config>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 14
+
+template <class _InputIterator, class _Size, class _Function>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _InputIterator for_each_n(_InputIterator __first,
+                                                                                         _Size __orig_n,
+                                                                                         _Function __f) {
+  typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
+  _IntegralSize __n = __orig_n;
+  while (__n > 0) {
+    __f(*__first);
+    ++__first;
+    --__n;
+  }
+  return __first;
+}
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_FOR_EACH_N_H

libcxx/include/__algorithm/generate.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_GENERATE_H
+#define _LIBCPP___ALGORITHM_GENERATE_H
+
+#include <__config>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator, class _Generator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+generate(_ForwardIterator __first, _ForwardIterator __last, _Generator __gen)
+{
+    for (; __first != __last; ++__first)
+        *__first = __gen();
+}
+
+// generate_n
+
+template <class _OutputIterator, class _Size, class _Generator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+generate_n(_OutputIterator __first, _Size __orig_n, _Generator __gen)
+{
+    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
+    _IntegralSize __n = __orig_n;
+    for (; __n > 0; ++__first, (void) --__n)
+        *__first = __gen();
+    return __first;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_GENERATE_H

libcxx/include/__algorithm/half_positive.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_HALF_POSITIVE_H
+#define _LIBCPP___ALGORITHM_HALF_POSITIVE_H
+
+#include <__config>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Perform division by two quickly for positive integers (llvm.org/PR39129)
+
+template <typename _Integral>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+typename enable_if
+<
+    is_integral<_Integral>::value,
+    _Integral
+>::type
+__half_positive(_Integral __value)
+{
+    return static_cast<_Integral>(static_cast<typename make_unsigned<_Integral>::type>(__value) / 2);
+}
+
+template <typename _Tp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+typename enable_if
+<
+    !is_integral<_Tp>::value,
+    _Tp
+>::type
+__half_positive(_Tp __value)
+{
+    return __value / 2;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_HALF_POSITIVE_H

libcxx/include/__algorithm/includes.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_INCLUDES_H
+#define _LIBCPP___ALGORITHM_INCLUDES_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
+           _Compare __comp)
+{
+    for (; __first2 != __last2; ++__first1)
+    {
+        if (__first1 == __last1 || __comp(*__first2, *__first1))
+            return false;
+        if (!__comp(*__first1, *__first2))
+            ++__first2;
+    }
+    return true;
+}
+
+template <class _InputIterator1, class _InputIterator2, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
+         _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__includes<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2)
+{
+    return _VSTD::includes(__first1, __last1, __first2, __last2,
+                          __less<typename iterator_traits<_InputIterator1>::value_type,
+                                 typename iterator_traits<_InputIterator2>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_INCLUDES_H

libcxx/include/__algorithm/inplace_merge.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_INPLACE_MERGE_H
+#define _LIBCPP___ALGORITHM_INPLACE_MERGE_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/rotate.h>
+#include <__algorithm/lower_bound.h>
+#include <__algorithm/min.h>
+#include <__algorithm/upper_bound.h>
+#include <__iterator/iterator_traits.h>
+#include <memory>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Predicate>
+class __invert // invert the sense of a comparison
+{
+private:
+    _Predicate __p_;
+public:
+    _LIBCPP_INLINE_VISIBILITY __invert() {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __invert(_Predicate __p) : __p_(__p) {}
+
+    template <class _T1>
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(const _T1& __x) {return !__p_(__x);}
+
+    template <class _T1, class _T2>
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
+};
+
+template <class _Compare, class _InputIterator1, class _InputIterator2,
+          class _OutputIterator>
+void __half_inplace_merge(_InputIterator1 __first1, _InputIterator1 __last1,
+                          _InputIterator2 __first2, _InputIterator2 __last2,
+                          _OutputIterator __result, _Compare __comp)
+{
+    for (; __first1 != __last1; ++__result)
+    {
+        if (__first2 == __last2)
+        {
+            _VSTD::move(__first1, __last1, __result);
+            return;
+        }
+
+        if (__comp(*__first2, *__first1))
+        {
+            *__result = _VSTD::move(*__first2);
+            ++__first2;
+        }
+        else
+        {
+            *__result = _VSTD::move(*__first1);
+            ++__first1;
+        }
+    }
+    // __first2 through __last2 are already in the right spot.
+}
+
+template <class _Compare, class _BidirectionalIterator>
+void
+__buffered_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
+                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
+                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
+                typename iterator_traits<_BidirectionalIterator>::value_type* __buff)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    __destruct_n __d(0);
+    unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
+    if (__len1 <= __len2)
+    {
+        value_type* __p = __buff;
+        for (_BidirectionalIterator __i = __first; __i != __middle; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
+            ::new ((void*)__p) value_type(_VSTD::move(*__i));
+        _VSTD::__half_inplace_merge<_Compare>(__buff, __p, __middle, __last, __first, __comp);
+    }
+    else
+    {
+        value_type* __p = __buff;
+        for (_BidirectionalIterator __i = __middle; __i != __last; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
+            ::new ((void*)__p) value_type(_VSTD::move(*__i));
+        typedef reverse_iterator<_BidirectionalIterator> _RBi;
+        typedef reverse_iterator<value_type*> _Rv;
+        typedef __invert<_Compare> _Inverted;
+        _VSTD::__half_inplace_merge<_Inverted>(_Rv(__p), _Rv(__buff),
+                                    _RBi(__middle), _RBi(__first),
+                                    _RBi(__last), _Inverted(__comp));
+    }
+}
+
+template <class _Compare, class _BidirectionalIterator>
+void
+__inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
+                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
+                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
+                typename iterator_traits<_BidirectionalIterator>::value_type* __buff, ptrdiff_t __buff_size)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
+    while (true)
+    {
+        // if __middle == __last, we're done
+        if (__len2 == 0)
+            return;
+        if (__len1 <= __buff_size || __len2 <= __buff_size)
+            return _VSTD::__buffered_inplace_merge<_Compare>
+                   (__first, __middle, __last, __comp, __len1, __len2, __buff);
+        // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
+        for (; true; ++__first, (void) --__len1)
+        {
+            if (__len1 == 0)
+                return;
+            if (__comp(*__middle, *__first))
+                break;
+        }
+        // __first < __middle < __last
+        // *__first > *__middle
+        // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
+        //     all elements in:
+        //         [__first, __m1)  <= [__middle, __m2)
+        //         [__middle, __m2) <  [__m1, __middle)
+        //         [__m1, __middle) <= [__m2, __last)
+        //     and __m1 or __m2 is in the middle of its range
+        _BidirectionalIterator __m1;  // "median" of [__first, __middle)
+        _BidirectionalIterator __m2;  // "median" of [__middle, __last)
+        difference_type __len11;      // distance(__first, __m1)
+        difference_type __len21;      // distance(__middle, __m2)
+        // binary search smaller range
+        if (__len1 < __len2)
+        {   // __len >= 1, __len2 >= 2
+            __len21 = __len2 / 2;
+            __m2 = __middle;
+            _VSTD::advance(__m2, __len21);
+            __m1 = _VSTD::__upper_bound<_Compare>(__first, __middle, *__m2, __comp);
+            __len11 = _VSTD::distance(__first, __m1);
+        }
+        else
+        {
+            if (__len1 == 1)
+            {   // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
+                // It is known *__first > *__middle
+                swap(*__first, *__middle);
+                return;
+            }
+            // __len1 >= 2, __len2 >= 1
+            __len11 = __len1 / 2;
+            __m1 = __first;
+            _VSTD::advance(__m1, __len11);
+            __m2 = _VSTD::__lower_bound<_Compare>(__middle, __last, *__m1, __comp);
+            __len21 = _VSTD::distance(__middle, __m2);
+        }
+        difference_type __len12 = __len1 - __len11;  // distance(__m1, __middle)
+        difference_type __len22 = __len2 - __len21;  // distance(__m2, __last)
+        // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
+        // swap middle two partitions
+        __middle = _VSTD::rotate(__m1, __middle, __m2);
+        // __len12 and __len21 now have swapped meanings
+        // merge smaller range with recursive call and larger with tail recursion elimination
+        if (__len11 + __len21 < __len12 + __len22)
+        {
+            _VSTD::__inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
+//          _VSTD::__inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
+            __first = __middle;
+            __middle = __m2;
+            __len1 = __len12;
+            __len2 = __len22;
+        }
+        else
+        {
+            _VSTD::__inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
+//          _VSTD::__inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
+            __last = __middle;
+            __middle = __m1;
+            __len1 = __len11;
+            __len2 = __len21;
+        }
+    }
+}
+
+template <class _BidirectionalIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
+              _Compare __comp)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
+    difference_type __len1 = _VSTD::distance(__first, __middle);
+    difference_type __len2 = _VSTD::distance(__middle, __last);
+    difference_type __buf_size = _VSTD::min(__len1, __len2);
+    pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
+    unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __comp, __len1, __len2,
+                                            __buf.first, __buf.second);
+}
+
+template <class _BidirectionalIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last)
+{
+    _VSTD::inplace_merge(__first, __middle, __last,
+                        __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_INPLACE_MERGE_H

libcxx/include/__algorithm/is_heap.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_IS_HEAP_H
+#define _LIBCPP___ALGORITHM_IS_HEAP_H
+
+#include <__config>
+#include <__algorithm/is_heap_until.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _RandomAccessIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    return _VSTD::is_heap_until(__first, __last, __comp) == __last;
+}
+
+template<class _RandomAccessIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    return _VSTD::is_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_IS_HEAP_H

libcxx/include/__algorithm/is_heap_until.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_IS_HEAP_UNTIL_H
+#define _LIBCPP___ALGORITHM_IS_HEAP_UNTIL_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _RandomAccessIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
+is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    difference_type __len = __last - __first;
+    difference_type __p = 0;
+    difference_type __c = 1;
+    _RandomAccessIterator __pp = __first;
+    while (__c < __len)
+    {
+        _RandomAccessIterator __cp = __first + __c;
+        if (__comp(*__pp, *__cp))
+            return __cp;
+        ++__c;
+        ++__cp;
+        if (__c == __len)
+            return __last;
+        if (__comp(*__pp, *__cp))
+            return __cp;
+        ++__p;
+        ++__pp;
+        __c = 2 * __p + 1;
+    }
+    return __last;
+}
+
+template<class _RandomAccessIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_RandomAccessIterator
+is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    return _VSTD::is_heap_until(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_IS_HEAP_UNTIL_H

libcxx/include/__algorithm/is_partitioned.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_IS_PARTITIONED_H
+#define _LIBCPP___ALGORITHM_IS_PARTITIONED_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+is_partitioned(_InputIterator __first, _InputIterator __last, _Predicate __pred)
+{
+    for (; __first != __last; ++__first)
+        if (!__pred(*__first))
+            break;
+    if ( __first == __last )
+        return true;
+    ++__first;
+    for (; __first != __last; ++__first)
+        if (__pred(*__first))
+            return false;
+    return true;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_IS_PARTITIONED_H

libcxx/include/__algorithm/is_permutation.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_IS_PERMUTATION_H
+#define _LIBCPP___ALGORITHM_IS_PERMUTATION_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <iterator> // FIXME: replace with <__iterator/distance.h> when it lands
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
+               _BinaryPredicate __pred) {
+  //  shorten sequences as much as possible by lopping of any equal prefix
+  for (; __first1 != __last1; ++__first1, (void)++__first2)
+    if (!__pred(*__first1, *__first2))
+      break;
+  if (__first1 == __last1)
+    return true;
+
+  //  __first1 != __last1 && *__first1 != *__first2
+  typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
+  _D1 __l1 = _VSTD::distance(__first1, __last1);
+  if (__l1 == _D1(1))
+    return false;
+  _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1);
+  // For each element in [f1, l1) see if there are the same number of
+  //    equal elements in [f2, l2)
+  for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) {
+    //  Have we already counted the number of *__i in [f1, l1)?
+    _ForwardIterator1 __match = __first1;
+    for (; __match != __i; ++__match)
+      if (__pred(*__match, *__i))
+        break;
+    if (__match == __i) {
+      // Count number of *__i in [f2, l2)
+      _D1 __c2 = 0;
+      for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
+        if (__pred(*__i, *__j))
+          ++__c2;
+      if (__c2 == 0)
+        return false;
+      // Count number of *__i in [__i, l1) (we can start with 1)
+      _D1 __c1 = 1;
+      for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
+        if (__pred(*__i, *__j))
+          ++__c1;
+      if (__c1 != __c2)
+        return false;
+    }
+  }
+  return true;
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
+  typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
+  typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
+  return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>());
+}
+
+#if _LIBCPP_STD_VER > 11
+template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
+                 _ForwardIterator2 __last2, _BinaryPredicate __pred, forward_iterator_tag, forward_iterator_tag) {
+  //  shorten sequences as much as possible by lopping of any equal prefix
+  for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void)++__first2)
+    if (!__pred(*__first1, *__first2))
+      break;
+  if (__first1 == __last1)
+    return __first2 == __last2;
+  else if (__first2 == __last2)
+    return false;
+
+  typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
+  _D1 __l1 = _VSTD::distance(__first1, __last1);
+
+  typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2;
+  _D2 __l2 = _VSTD::distance(__first2, __last2);
+  if (__l1 != __l2)
+    return false;
+
+  // For each element in [f1, l1) see if there are the same number of
+  //    equal elements in [f2, l2)
+  for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) {
+    //  Have we already counted the number of *__i in [f1, l1)?
+    _ForwardIterator1 __match = __first1;
+    for (; __match != __i; ++__match)
+      if (__pred(*__match, *__i))
+        break;
+    if (__match == __i) {
+      // Count number of *__i in [f2, l2)
+      _D1 __c2 = 0;
+      for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
+        if (__pred(*__i, *__j))
+          ++__c2;
+      if (__c2 == 0)
+        return false;
+      // Count number of *__i in [__i, l1) (we can start with 1)
+      _D1 __c1 = 1;
+      for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
+        if (__pred(*__i, *__j))
+          ++__c1;
+      if (__c1 != __c2)
+        return false;
+    }
+  }
+  return true;
+}
+
+template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 bool __is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1,
+                                                    _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2,
+                                                    _BinaryPredicate __pred, random_access_iterator_tag,
+                                                    random_access_iterator_tag) {
+  if (_VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
+    return false;
+  return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2,
+                               typename add_lvalue_reference<_BinaryPredicate>::type>(__first1, __last1, __first2,
+                                                                                      __pred);
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
+               _ForwardIterator2 __last2, _BinaryPredicate __pred) {
+  return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>(
+      __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(),
+      typename iterator_traits<_ForwardIterator2>::iterator_category());
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
+               _ForwardIterator2 __last2) {
+  typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
+  typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
+  return _VSTD::__is_permutation(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(),
+                                 typename iterator_traits<_ForwardIterator1>::iterator_category(),
+                                 typename iterator_traits<_ForwardIterator2>::iterator_category());
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H

libcxx/include/__algorithm/is_sorted.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_IS_SORTED_H
+#define _LIBCPP___ALGORITHM_IS_SORTED_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// is_sorted_until
+
+template <class _ForwardIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+is_sorted_until(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+    if (__first != __last)
+    {
+        _ForwardIterator __i = __first;
+        while (++__i != __last)
+        {
+            if (__comp(*__i, *__first))
+                return __i;
+            __first = __i;
+        }
+    }
+    return __last;
+}
+
+template<class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
+{
+    return _VSTD::is_sorted_until(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
+}
+
+// is_sorted
+
+template <class _ForwardIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+is_sorted(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+    return _VSTD::is_sorted_until(__first, __last, __comp) == __last;
+}
+
+template<class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+is_sorted(_ForwardIterator __first, _ForwardIterator __last)
+{
+    return _VSTD::is_sorted(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_IS_SORTED_H

libcxx/include/__algorithm/lexicographical_compare.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_H
+#define _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
+                          _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
+{
+    for (; __first2 != __last2; ++__first1, (void) ++__first2)
+    {
+        if (__first1 == __last1 || __comp(*__first1, *__first2))
+            return true;
+        if (__comp(*__first2, *__first1))
+            return false;
+    }
+    return false;
+}
+
+template <class _InputIterator1, class _InputIterator2, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
+                        _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__lexicographical_compare<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
+                        _InputIterator2 __first2, _InputIterator2 __last2)
+{
+    return _VSTD::lexicographical_compare(__first1, __last1, __first2, __last2,
+                                         __less<typename iterator_traits<_InputIterator1>::value_type,
+                                                typename iterator_traits<_InputIterator2>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_H

libcxx/include/__algorithm/lower_bound.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_LOWER_BOUND_H
+#define _LIBCPP___ALGORITHM_LOWER_BOUND_H
+
+#include <__config>
+#include <__algorithm/half_positive.h>
+#include <__algorithm/comp.h>
+#include <iterator>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _ForwardIterator, class _Tp>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+__lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
+    difference_type __len = _VSTD::distance(__first, __last);
+    while (__len != 0)
+    {
+        difference_type __l2 = _VSTD::__half_positive(__len);
+        _ForwardIterator __m = __first;
+        _VSTD::advance(__m, __l2);
+        if (__comp(*__m, __value_))
+        {
+            __first = ++__m;
+            __len -= __l2 + 1;
+        }
+        else
+            __len = __l2;
+    }
+    return __first;
+}
+
+template <class _ForwardIterator, class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
+    return _VSTD::__lower_bound<_Comp_ref>(__first, __last, __value_, __comp);
+}
+
+template <class _ForwardIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
+{
+    return _VSTD::lower_bound(__first, __last, __value_,
+                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_LOWER_BOUND_H

libcxx/include/__algorithm/make_heap.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MAKE_HEAP_H
+#define _LIBCPP___ALGORITHM_MAKE_HEAP_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/sift_down.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 void
+__make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    difference_type __n = __last - __first;
+    if (__n > 1)
+    {
+        // start from the first parent, there is no need to consider children
+        for (difference_type __start = (__n - 2) / 2; __start >= 0; --__start)
+        {
+            _VSTD::__sift_down<_Compare>(__first, __last, __comp, __n, __first + __start);
+        }
+    }
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__make_heap<_Comp_ref>(__first, __last, __comp);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    _VSTD::make_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MAKE_HEAP_H

libcxx/include/__algorithm/max.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MAX_H
+#define _LIBCPP___ALGORITHM_MAX_H
+
+#include <__config>
+#include <__algorithm/comp.h>
+#include <__algorithm/max_element.h>
+#include <initializer_list>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const _Tp&
+max(const _Tp& __a, const _Tp& __b, _Compare __comp)
+{
+    return __comp(__a, __b) ? __b : __a;
+}
+
+template <class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const _Tp&
+max(const _Tp& __a, const _Tp& __b)
+{
+    return _VSTD::max(__a, __b, __less<_Tp>());
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template<class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_Tp
+max(initializer_list<_Tp> __t, _Compare __comp)
+{
+    return *_VSTD::max_element(__t.begin(), __t.end(), __comp);
+}
+
+template<class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_Tp
+max(initializer_list<_Tp> __t)
+{
+    return *_VSTD::max_element(__t.begin(), __t.end(), __less<_Tp>());
+}
+
+#endif // _LIBCPP_CXX03_LANG
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MAX_H

libcxx/include/__algorithm/max_element.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MAX_ELEMENT_H
+#define _LIBCPP___ALGORITHM_MAX_ELEMENT_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_ForwardIterator
+max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
+        "std::max_element requires a ForwardIterator");
+    if (__first != __last)
+    {
+        _ForwardIterator __i = __first;
+        while (++__i != __last)
+            if (__comp(*__first, *__i))
+                __first = __i;
+    }
+    return __first;
+}
+
+
+template <class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_ForwardIterator
+max_element(_ForwardIterator __first, _ForwardIterator __last)
+{
+    return _VSTD::max_element(__first, __last,
+              __less<typename iterator_traits<_ForwardIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MAX_ELEMENT_H

libcxx/include/__algorithm/merge.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MERGE_H
+#define _LIBCPP___ALGORITHM_MERGE_H
+
+#include <__config>
+#include <__algorithm/copy.h>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+__merge(_InputIterator1 __first1, _InputIterator1 __last1,
+        _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    for (; __first1 != __last1; ++__result)
+    {
+        if (__first2 == __last2)
+            return _VSTD::copy(__first1, __last1, __result);
+        if (__comp(*__first2, *__first1))
+        {
+            *__result = *__first2;
+            ++__first2;
+        }
+        else
+        {
+            *__result = *__first1;
+            ++__first1;
+        }
+    }
+    return _VSTD::copy(__first2, __last2, __result);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+merge(_InputIterator1 __first1, _InputIterator1 __last1,
+      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__merge<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+merge(_InputIterator1 __first1, _InputIterator1 __last1,
+      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
+{
+    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
+    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
+    return _VSTD::merge(__first1, __last1, __first2, __last2, __result, __less<__v1, __v2>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MERGE_H

libcxx/include/__algorithm/min.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MIN_H
+#define _LIBCPP___ALGORITHM_MIN_H
+
+#include <__config>
+#include <__algorithm/comp.h>
+#include <__algorithm/min_element.h>
+#include <initializer_list>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const _Tp&
+min(const _Tp& __a, const _Tp& __b, _Compare __comp)
+{
+    return __comp(__b, __a) ? __b : __a;
+}
+
+template <class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const _Tp&
+min(const _Tp& __a, const _Tp& __b)
+{
+    return _VSTD::min(__a, __b, __less<_Tp>());
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template<class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_Tp
+min(initializer_list<_Tp> __t, _Compare __comp)
+{
+    return *_VSTD::min_element(__t.begin(), __t.end(), __comp);
+}
+
+template<class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_Tp
+min(initializer_list<_Tp> __t)
+{
+    return *_VSTD::min_element(__t.begin(), __t.end(), __less<_Tp>());
+}
+
+#endif // _LIBCPP_CXX03_LANG
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MIN_H

libcxx/include/__algorithm/min_element.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MIN_ELEMENT_H
+#define _LIBCPP___ALGORITHM_MIN_ELEMENT_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_ForwardIterator
+min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
+        "std::min_element requires a ForwardIterator");
+    if (__first != __last)
+    {
+        _ForwardIterator __i = __first;
+        while (++__i != __last)
+            if (__comp(*__i, *__first))
+                __first = __i;
+    }
+    return __first;
+}
+
+template <class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+_ForwardIterator
+min_element(_ForwardIterator __first, _ForwardIterator __last)
+{
+    return _VSTD::min_element(__first, __last,
+              __less<typename iterator_traits<_ForwardIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MIN_ELEMENT_H

libcxx/include/__algorithm/minmax.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MINMAX_H
+#define _LIBCPP___ALGORITHM_MINMAX_H
+
+#include <__config>
+#include <utility>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template<class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<const _Tp&, const _Tp&>
+minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
+{
+    return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a) :
+                              pair<const _Tp&, const _Tp&>(__a, __b);
+}
+
+template<class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<const _Tp&, const _Tp&>
+minmax(const _Tp& __a, const _Tp& __b)
+{
+    return _VSTD::minmax(__a, __b, __less<_Tp>());
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template<class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<_Tp, _Tp>
+minmax(initializer_list<_Tp> __t, _Compare __comp)
+{
+    typedef typename initializer_list<_Tp>::const_iterator _Iter;
+    _Iter __first = __t.begin();
+    _Iter __last  = __t.end();
+    pair<_Tp, _Tp> __result(*__first, *__first);
+
+    ++__first;
+    if (__t.size() % 2 == 0)
+    {
+        if (__comp(*__first,  __result.first))
+            __result.first  = *__first;
+        else
+            __result.second = *__first;
+        ++__first;
+    }
+
+    while (__first != __last)
+    {
+        _Tp __prev = *__first++;
+        if (__comp(*__first, __prev)) {
+            if ( __comp(*__first, __result.first)) __result.first  = *__first;
+            if (!__comp(__prev, __result.second))  __result.second = __prev;
+            }
+        else {
+            if ( __comp(__prev, __result.first))    __result.first  = __prev;
+            if (!__comp(*__first, __result.second)) __result.second = *__first;
+            }
+
+        __first++;
+    }
+    return __result;
+}
+
+template<class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<_Tp, _Tp>
+minmax(initializer_list<_Tp> __t)
+{
+    return _VSTD::minmax(__t, __less<_Tp>());
+}
+
+#endif // _LIBCPP_CXX03_LANG
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MINMAX_H

libcxx/include/__algorithm/minmax_element.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H
+#define _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <utility>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator, class _Compare>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<_ForwardIterator, _ForwardIterator>
+minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+  static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
+        "std::minmax_element requires a ForwardIterator");
+  pair<_ForwardIterator, _ForwardIterator> __result(__first, __first);
+  if (__first != __last)
+  {
+      if (++__first != __last)
+      {
+          if (__comp(*__first, *__result.first))
+              __result.first = __first;
+          else
+              __result.second = __first;
+          while (++__first != __last)
+          {
+              _ForwardIterator __i = __first;
+              if (++__first == __last)
+              {
+                  if (__comp(*__i, *__result.first))
+                      __result.first = __i;
+                  else if (!__comp(*__i, *__result.second))
+                      __result.second = __i;
+                  break;
+              }
+              else
+              {
+                  if (__comp(*__first, *__i))
+                  {
+                      if (__comp(*__first, *__result.first))
+                          __result.first = __first;
+                      if (!__comp(*__i, *__result.second))
+                          __result.second = __i;
+                  }
+                  else
+                  {
+                      if (__comp(*__i, *__result.first))
+                          __result.first = __i;
+                      if (!__comp(*__first, *__result.second))
+                          __result.second = __first;
+                  }
+              }
+          }
+      }
+  }
+  return __result;
+}
+
+template <class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<_ForwardIterator, _ForwardIterator>
+minmax_element(_ForwardIterator __first, _ForwardIterator __last)
+{
+    return _VSTD::minmax_element(__first, __last,
+              __less<typename iterator_traits<_ForwardIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H

libcxx/include/__algorithm/mismatch.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MISMATCH_H
+#define _LIBCPP___ALGORITHM_MISMATCH_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <utility>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_InputIterator1, _InputIterator2>
+    mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred) {
+  for (; __first1 != __last1; ++__first1, (void)++__first2)
+    if (!__pred(*__first1, *__first2))
+      break;
+  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
+}
+
+template <class _InputIterator1, class _InputIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_InputIterator1, _InputIterator2>
+    mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2) {
+  typedef typename iterator_traits<_InputIterator1>::value_type __v1;
+  typedef typename iterator_traits<_InputIterator2>::value_type __v2;
+  return _VSTD::mismatch(__first1, __last1, __first2, __equal_to<__v1, __v2>());
+}
+
+#if _LIBCPP_STD_VER > 11
+template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_InputIterator1, _InputIterator2>
+    mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
+             _BinaryPredicate __pred) {
+  for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void)++__first2)
+    if (!__pred(*__first1, *__first2))
+      break;
+  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
+}
+
+template <class _InputIterator1, class _InputIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_InputIterator1, _InputIterator2>
+    mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2) {
+  typedef typename iterator_traits<_InputIterator1>::value_type __v1;
+  typedef typename iterator_traits<_InputIterator2>::value_type __v2;
+  return _VSTD::mismatch(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MISMATCH_H

libcxx/include/__algorithm/move.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_MOVE_H
+#define _LIBCPP___ALGORITHM_MOVE_H
+
+#include <__config>
+#include <__algorithm/unwrap_iter.h>
+#include <cstring>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// move
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+_OutputIterator
+__move_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    for (; __first != __last; ++__first, (void) ++__result)
+        *__result = _VSTD::move(*__first);
+    return __result;
+}
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+_OutputIterator
+__move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    return _VSTD::__move_constexpr(__first, __last, __result);
+}
+
+template <class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+typename enable_if
+<
+    is_same<typename remove_const<_Tp>::type, _Up>::value &&
+    is_trivially_move_assignable<_Up>::value,
+    _Up*
+>::type
+__move(_Tp* __first, _Tp* __last, _Up* __result)
+{
+    const size_t __n = static_cast<size_t>(__last - __first);
+    if (__n > 0)
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    return __result + __n;
+}
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    if (__libcpp_is_constant_evaluated()) {
+        return _VSTD::__move_constexpr(__first, __last, __result);
+    } else {
+        return _VSTD::__rewrap_iter(__result,
+            _VSTD::__move(_VSTD::__unwrap_iter(__first),
+                          _VSTD::__unwrap_iter(__last),
+                          _VSTD::__unwrap_iter(__result)));
+    }
+}
+
+// move_backward
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+_OutputIterator
+__move_backward_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    while (__first != __last)
+        *--__result = _VSTD::move(*--__last);
+    return __result;
+}
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+_OutputIterator
+__move_backward(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    return _VSTD::__move_backward_constexpr(__first, __last, __result);
+}
+
+template <class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+typename enable_if
+<
+    is_same<typename remove_const<_Tp>::type, _Up>::value &&
+    is_trivially_move_assignable<_Up>::value,
+    _Up*
+>::type
+__move_backward(_Tp* __first, _Tp* __last, _Up* __result)
+{
+    const size_t __n = static_cast<size_t>(__last - __first);
+    if (__n > 0)
+    {
+        __result -= __n;
+        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
+    }
+    return __result;
+}
+
+template <class _BidirectionalIterator1, class _BidirectionalIterator2>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_BidirectionalIterator2
+move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
+              _BidirectionalIterator2 __result)
+{
+    if (__libcpp_is_constant_evaluated()) {
+        return _VSTD::__move_backward_constexpr(__first, __last, __result);
+    } else {
+        return _VSTD::__rewrap_iter(__result,
+            _VSTD::__move_backward(_VSTD::__unwrap_iter(__first),
+                                   _VSTD::__unwrap_iter(__last),
+                                   _VSTD::__unwrap_iter(__result)));
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_MOVE_H

libcxx/include/__algorithm/next_permutation.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H
+#define _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/reverse.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _BidirectionalIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
+{
+    _BidirectionalIterator __i = __last;
+    if (__first == __last || __first == --__i)
+        return false;
+    while (true)
+    {
+        _BidirectionalIterator __ip1 = __i;
+        if (__comp(*--__i, *__ip1))
+        {
+            _BidirectionalIterator __j = __last;
+            while (!__comp(*__i, *--__j))
+                ;
+            swap(*__i, *__j);
+            _VSTD::reverse(__ip1, __last);
+            return true;
+        }
+        if (__i == __first)
+        {
+            _VSTD::reverse(__first, __last);
+            return false;
+        }
+    }
+}
+
+template <class _BidirectionalIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__next_permutation<_Comp_ref>(__first, __last, __comp);
+}
+
+template <class _BidirectionalIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
+{
+    return _VSTD::next_permutation(__first, __last,
+                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H

libcxx/include/__algorithm/none_of.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_NONE_OF_H
+#define _LIBCPP___ALGORITHM_NONE_OF_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
+  for (; __first != __last; ++__first)
+    if (__pred(*__first))
+      return false;
+  return true;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_NONE_OF_H

libcxx/include/__algorithm/nth_element.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_NTH_ELEMENT_H
+#define _LIBCPP___ALGORITHM_NTH_ELEMENT_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/sort.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template<class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 bool
+__nth_element_find_guard(_RandomAccessIterator& __i, _RandomAccessIterator& __j,
+                         _RandomAccessIterator __m, _Compare __comp)
+{
+    // manually guard downward moving __j against __i
+    while (true) {
+        if (__i == --__j) {
+            return false;
+        }
+        if (__comp(*__j, *__m)) {
+            return true;  // found guard for downward moving __j, now use unguarded partition
+        }
+    }
+}
+
+template <class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 void
+__nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
+{
+    // _Compare is known to be a reference type
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    const difference_type __limit = 7;
+    while (true)
+    {
+        if (__nth == __last)
+            return;
+        difference_type __len = __last - __first;
+        switch (__len)
+        {
+        case 0:
+        case 1:
+            return;
+        case 2:
+            if (__comp(*--__last, *__first))
+                swap(*__first, *__last);
+            return;
+        case 3:
+            {
+            _RandomAccessIterator __m = __first;
+            _VSTD::__sort3<_Compare>(__first, ++__m, --__last, __comp);
+            return;
+            }
+        }
+        if (__len <= __limit)
+        {
+            _VSTD::__selection_sort<_Compare>(__first, __last, __comp);
+            return;
+        }
+        // __len > __limit >= 3
+        _RandomAccessIterator __m = __first + __len/2;
+        _RandomAccessIterator __lm1 = __last;
+        unsigned __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, --__lm1, __comp);
+        // *__m is median
+        // partition [__first, __m) < *__m and *__m <= [__m, __last)
+        // (this inhibits tossing elements equivalent to __m around unnecessarily)
+        _RandomAccessIterator __i = __first;
+        _RandomAccessIterator __j = __lm1;
+        // j points beyond range to be tested, *__lm1 is known to be <= *__m
+        // The search going up is known to be guarded but the search coming down isn't.
+        // Prime the downward search with a guard.
+        if (!__comp(*__i, *__m))  // if *__first == *__m
+        {
+            // *__first == *__m, *__first doesn't go in first part
+            if (_VSTD::__nth_element_find_guard<_Compare>(__i, __j, __m, __comp)) {
+                swap(*__i, *__j);
+                ++__n_swaps;
+            } else {
+                // *__first == *__m, *__m <= all other elements
+                // Partition instead into [__first, __i) == *__first and *__first < [__i, __last)
+                ++__i;  // __first + 1
+                __j = __last;
+                if (!__comp(*__first, *--__j)) {  // we need a guard if *__first == *(__last-1)
+                    while (true) {
+                        if (__i == __j) {
+                            return;  // [__first, __last) all equivalent elements
+                        } else if (__comp(*__first, *__i)) {
+                            swap(*__i, *__j);
+                            ++__n_swaps;
+                            ++__i;
+                            break;
+                        }
+                        ++__i;
+                    }
+                }
+                // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
+                if (__i == __j) {
+                    return;
+                }
+                while (true) {
+                    while (!__comp(*__first, *__i))
+                        ++__i;
+                    while (__comp(*__first, *--__j))
+                        ;
+                    if (__i >= __j)
+                        break;
+                    swap(*__i, *__j);
+                    ++__n_swaps;
+                    ++__i;
+                }
+                // [__first, __i) == *__first and *__first < [__i, __last)
+                // The first part is sorted,
+                if (__nth < __i) {
+                    return;
+                }
+                // __nth_element the second part
+                // _VSTD::__nth_element<_Compare>(__i, __nth, __last, __comp);
+                __first = __i;
+                continue;
+            }
+        }
+        ++__i;
+        // j points beyond range to be tested, *__lm1 is known to be <= *__m
+        // if not yet partitioned...
+        if (__i < __j)
+        {
+            // known that *(__i - 1) < *__m
+            while (true)
+            {
+                // __m still guards upward moving __i
+                while (__comp(*__i, *__m))
+                    ++__i;
+                // It is now known that a guard exists for downward moving __j
+                while (!__comp(*--__j, *__m))
+                    ;
+                if (__i >= __j)
+                    break;
+                swap(*__i, *__j);
+                ++__n_swaps;
+                // It is known that __m != __j
+                // If __m just moved, follow it
+                if (__m == __i)
+                    __m = __j;
+                ++__i;
+            }
+        }
+        // [__first, __i) < *__m and *__m <= [__i, __last)
+        if (__i != __m && __comp(*__m, *__i))
+        {
+            swap(*__i, *__m);
+            ++__n_swaps;
+        }
+        // [__first, __i) < *__i and *__i <= [__i+1, __last)
+        if (__nth == __i)
+            return;
+        if (__n_swaps == 0)
+        {
+            // We were given a perfectly partitioned sequence.  Coincidence?
+            if (__nth < __i)
+            {
+                // Check for [__first, __i) already sorted
+                __j = __m = __first;
+                while (true) {
+                    if (++__j == __i) {
+                        // [__first, __i) sorted
+                        return;
+                    }
+                    if (__comp(*__j, *__m)) {
+                        // not yet sorted, so sort
+                        break;
+                    }
+                    __m = __j;
+                }
+            }
+            else
+            {
+                // Check for [__i, __last) already sorted
+                __j = __m = __i;
+                while (true) {
+                    if (++__j == __last) {
+                        // [__i, __last) sorted
+                        return;
+                    }
+                    if (__comp(*__j, *__m)) {
+                        // not yet sorted, so sort
+                        break;
+                    }
+                    __m = __j;
+                }
+            }
+        }
+        // __nth_element on range containing __nth
+        if (__nth < __i)
+        {
+            // _VSTD::__nth_element<_Compare>(__first, __nth, __i, __comp);
+            __last = __i;
+        }
+        else
+        {
+            // _VSTD::__nth_element<_Compare>(__i+1, __nth, __last, __comp);
+            __first = ++__i;
+        }
+    }
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__nth_element<_Comp_ref>(__first, __nth, __last, __comp);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last)
+{
+    _VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_NTH_ELEMENT_H

libcxx/include/__algorithm/partial_sort.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PARTIAL_SORT_H
+#define _LIBCPP___ALGORITHM_PARTIAL_SORT_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/make_heap.h>
+#include <__algorithm/sift_down.h>
+#include <__algorithm/sort_heap.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 void
+__partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
+             _Compare __comp)
+{
+    _VSTD::__make_heap<_Compare>(__first, __middle, __comp);
+    typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
+    for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
+    {
+        if (__comp(*__i, *__first))
+        {
+            swap(*__i, *__first);
+            _VSTD::__sift_down<_Compare>(__first, __middle, __comp, __len, __first);
+        }
+    }
+    _VSTD::__sort_heap<_Compare>(__first, __middle, __comp);
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
+             _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
+{
+    _VSTD::partial_sort(__first, __middle, __last,
+                       __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+// partial_sort_copy
+
+template <class _Compare, class _InputIterator, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
+__partial_sort_copy(_InputIterator __first, _InputIterator __last,
+                    _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
+{
+    _RandomAccessIterator __r = __result_first;
+    if (__r != __result_last)
+    {
+        for (; __first != __last && __r != __result_last; ++__first, (void) ++__r)
+            *__r = *__first;
+        _VSTD::__make_heap<_Compare>(__result_first, __r, __comp);
+        typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
+        for (; __first != __last; ++__first)
+            if (__comp(*__first, *__result_first))
+            {
+                *__result_first = *__first;
+                _VSTD::__sift_down<_Compare>(__result_first, __r, __comp, __len, __result_first);
+            }
+        _VSTD::__sort_heap<_Compare>(__result_first, __r, __comp);
+    }
+    return __r;
+}
+
+template <class _InputIterator, class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_RandomAccessIterator
+partial_sort_copy(_InputIterator __first, _InputIterator __last,
+                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __comp);
+}
+
+template <class _InputIterator, class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_RandomAccessIterator
+partial_sort_copy(_InputIterator __first, _InputIterator __last,
+                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
+{
+    return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
+                                   __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_H

libcxx/include/__algorithm/partition.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PARTITION_H
+#define _LIBCPP___ALGORITHM_PARTITION_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// partition
+
+template <class _Predicate, class _ForwardIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+__partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag)
+{
+    while (true)
+    {
+        if (__first == __last)
+            return __first;
+        if (!__pred(*__first))
+            break;
+        ++__first;
+    }
+    for (_ForwardIterator __p = __first; ++__p != __last;)
+    {
+        if (__pred(*__p))
+        {
+            swap(*__first, *__p);
+            ++__first;
+        }
+    }
+    return __first;
+}
+
+template <class _Predicate, class _BidirectionalIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator
+__partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
+            bidirectional_iterator_tag)
+{
+    while (true)
+    {
+        while (true)
+        {
+            if (__first == __last)
+                return __first;
+            if (!__pred(*__first))
+                break;
+            ++__first;
+        }
+        do
+        {
+            if (__first == --__last)
+                return __first;
+        } while (!__pred(*__last));
+        swap(*__first, *__last);
+        ++__first;
+    }
+}
+
+template <class _ForwardIterator, class _Predicate>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
+{
+    return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type>
+                            (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
+}
+
+// partition_copy
+
+template <class _InputIterator, class _OutputIterator1,
+          class _OutputIterator2, class _Predicate>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_OutputIterator1, _OutputIterator2>
+partition_copy(_InputIterator __first, _InputIterator __last,
+               _OutputIterator1 __out_true, _OutputIterator2 __out_false,
+               _Predicate __pred)
+{
+    for (; __first != __last; ++__first)
+    {
+        if (__pred(*__first))
+        {
+            *__out_true = *__first;
+            ++__out_true;
+        }
+        else
+        {
+            *__out_false = *__first;
+            ++__out_false;
+        }
+    }
+    return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_PARTITION_H

libcxx/include/__algorithm/partition_point.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PARTITION_POINT_H
+#define _LIBCPP___ALGORITHM_PARTITION_POINT_H
+
+#include <__config>
+#include <__algorithm/half_positive.h>
+#include <iterator>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template<class _ForwardIterator, class _Predicate>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
+{
+    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
+    difference_type __len = _VSTD::distance(__first, __last);
+    while (__len != 0)
+    {
+        difference_type __l2 = _VSTD::__half_positive(__len);
+        _ForwardIterator __m = __first;
+        _VSTD::advance(__m, __l2);
+        if (__pred(*__m))
+        {
+            __first = ++__m;
+            __len -= __l2 + 1;
+        }
+        else
+            __len = __l2;
+    }
+    return __first;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_PARTITION_POINT_H

libcxx/include/__algorithm/pop_heap.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_POP_HEAP_H
+#define _LIBCPP___ALGORITHM_POP_HEAP_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/sift_down.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+__pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
+           typename iterator_traits<_RandomAccessIterator>::difference_type __len)
+{
+    if (__len > 1)
+    {
+        swap(*__first, *--__last);
+        _VSTD::__sift_down<_Compare>(__first, __last, __comp, __len - 1, __first);
+    }
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__pop_heap<_Comp_ref>(__first, __last, __comp, __last - __first);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    _VSTD::pop_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_POP_HEAP_H

libcxx/include/__algorithm/prev_permutation.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
+#define _LIBCPP___ALGORITHM_PREV_PERMUTATION_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/comp.h>
+#include <__algorithm/reverse.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _BidirectionalIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
+__prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
+{
+    _BidirectionalIterator __i = __last;
+    if (__first == __last || __first == --__i)
+        return false;
+    while (true)
+    {
+        _BidirectionalIterator __ip1 = __i;
+        if (__comp(*__ip1, *--__i))
+        {
+            _BidirectionalIterator __j = __last;
+            while (!__comp(*--__j, *__i))
+                ;
+            swap(*__i, *__j);
+            _VSTD::reverse(__ip1, __last);
+            return true;
+        }
+        if (__i == __first)
+        {
+            _VSTD::reverse(__first, __last);
+            return false;
+        }
+    }
+}
+
+template <class _BidirectionalIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__prev_permutation<_Comp_ref>(__first, __last, __comp);
+}
+
+template <class _BidirectionalIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+bool
+prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
+{
+    return _VSTD::prev_permutation(__first, __last,
+                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_PREV_PERMUTATION_H

libcxx/include/__algorithm/push_heap.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_PUSH_HEAP_H
+#define _LIBCPP___ALGORITHM_PUSH_HEAP_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 void
+__sift_up(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
+          typename iterator_traits<_RandomAccessIterator>::difference_type __len)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    if (__len > 1)
+    {
+        __len = (__len - 2) / 2;
+        _RandomAccessIterator __ptr = __first + __len;
+        if (__comp(*__ptr, *--__last))
+        {
+            value_type __t(_VSTD::move(*__last));
+            do
+            {
+                *__last = _VSTD::move(*__ptr);
+                __last = __ptr;
+                if (__len == 0)
+                    break;
+                __len = (__len - 1) / 2;
+                __ptr = __first + __len;
+            } while (__comp(*__ptr, __t));
+            *__last = _VSTD::move(__t);
+        }
+    }
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__sift_up<_Comp_ref>(__first, __last, __comp, __last - __first);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    _VSTD::push_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_PUSH_HEAP_H

libcxx/include/__algorithm/remove.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_REMOVE_H
+#define _LIBCPP___ALGORITHM_REMOVE_H
+
+#include <__config>
+#include <__algorithm/find.h>
+#include <__algorithm/find_if.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// remove
+
+template <class _ForwardIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+remove(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
+{
+    __first = _VSTD::find(__first, __last, __value_);
+    if (__first != __last)
+    {
+        _ForwardIterator __i = __first;
+        while (++__i != __last)
+        {
+            if (!(*__i == __value_))
+            {
+                *__first = _VSTD::move(*__i);
+                ++__first;
+            }
+        }
+    }
+    return __first;
+}
+
+// remove_if
+
+template <class _ForwardIterator, class _Predicate>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+remove_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
+{
+    __first = _VSTD::find_if<_ForwardIterator, typename add_lvalue_reference<_Predicate>::type>
+                           (__first, __last, __pred);
+    if (__first != __last)
+    {
+        _ForwardIterator __i = __first;
+        while (++__i != __last)
+        {
+            if (!__pred(*__i))
+            {
+                *__first = _VSTD::move(*__i);
+                ++__first;
+            }
+        }
+    }
+    return __first;
+}
+
+// remove_copy
+
+template <class _InputIterator, class _OutputIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+remove_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, const _Tp& __value_)
+{
+    for (; __first != __last; ++__first)
+    {
+        if (!(*__first == __value_))
+        {
+            *__result = *__first;
+            ++__result;
+        }
+    }
+    return __result;
+}
+
+// remove_copy_if
+
+template <class _InputIterator, class _OutputIterator, class _Predicate>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+remove_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _Predicate __pred)
+{
+    for (; __first != __last; ++__first)
+    {
+        if (!__pred(*__first))
+        {
+            *__result = *__first;
+            ++__result;
+        }
+    }
+    return __result;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_REMOVE_H

libcxx/include/__algorithm/replace.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_REPLACE_H
+#define _LIBCPP___ALGORITHM_REPLACE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// replace
+
+template <class _ForwardIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+replace(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __old_value, const _Tp& __new_value)
+{
+    for (; __first != __last; ++__first)
+        if (*__first == __old_value)
+            *__first = __new_value;
+}
+
+// replace_if
+
+template <class _ForwardIterator, class _Predicate, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+replace_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, const _Tp& __new_value)
+{
+    for (; __first != __last; ++__first)
+        if (__pred(*__first))
+            *__first = __new_value;
+}
+
+// replace_copy
+
+template <class _InputIterator, class _OutputIterator, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+replace_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
+             const _Tp& __old_value, const _Tp& __new_value)
+{
+    for (; __first != __last; ++__first, (void) ++__result)
+        if (*__first == __old_value)
+            *__result = __new_value;
+        else
+            *__result = *__first;
+    return __result;
+}
+
+// replace_copy_if
+
+template <class _InputIterator, class _OutputIterator, class _Predicate, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+replace_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
+                _Predicate __pred, const _Tp& __new_value)
+{
+    for (; __first != __last; ++__first, (void) ++__result)
+        if (__pred(*__first))
+            *__result = __new_value;
+        else
+            *__result = *__first;
+    return __result;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_REPLACE_H

libcxx/include/__algorithm/reverse.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_REVERSE_H
+#define _LIBCPP___ALGORITHM_REVERSE_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// reverse
+
+template <class _BidirectionalIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
+{
+    while (__first != __last)
+    {
+        if (__first == --__last)
+            break;
+        _VSTD::iter_swap(__first, __last);
+        ++__first;
+    }
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
+{
+    if (__first != __last)
+        for (; __first < --__last; ++__first)
+            _VSTD::iter_swap(__first, __last);
+}
+
+template <class _BidirectionalIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
+{
+    _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
+}
+
+// reverse_copy
+
+template <class _BidirectionalIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
+{
+    for (; __first != __last; ++__result)
+        *__result = *--__last;
+    return __result;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_REVERSE_H

libcxx/include/__algorithm/rotate.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_ROTATE_H
+#define _LIBCPP___ALGORITHM_ROTATE_H
+
+#include <__config>
+#include <iterator>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// rotate
+
+template <class _ForwardIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator
+__rotate_left(_ForwardIterator __first, _ForwardIterator __last)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+    value_type __tmp = _VSTD::move(*__first);
+    _ForwardIterator __lm1 = _VSTD::move(_VSTD::next(__first), __last, __first);
+    *__lm1 = _VSTD::move(__tmp);
+    return __lm1;
+}
+
+template <class _BidirectionalIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _BidirectionalIterator
+__rotate_right(_BidirectionalIterator __first, _BidirectionalIterator __last)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    _BidirectionalIterator __lm1 = _VSTD::prev(__last);
+    value_type __tmp = _VSTD::move(*__lm1);
+    _BidirectionalIterator __fp1 = _VSTD::move_backward(__first, __lm1, __last);
+    *__first = _VSTD::move(__tmp);
+    return __fp1;
+}
+
+template <class _ForwardIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX14 _ForwardIterator
+__rotate_forward(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
+{
+    _ForwardIterator __i = __middle;
+    while (true)
+    {
+        swap(*__first, *__i);
+        ++__first;
+        if (++__i == __last)
+            break;
+        if (__first == __middle)
+            __middle = __i;
+    }
+    _ForwardIterator __r = __first;
+    if (__first != __middle)
+    {
+        __i = __middle;
+        while (true)
+        {
+            swap(*__first, *__i);
+            ++__first;
+            if (++__i == __last)
+            {
+                if (__first == __middle)
+                    break;
+                __i = __middle;
+            }
+            else if (__first == __middle)
+                __middle = __i;
+        }
+    }
+    return __r;
+}
+
+template<typename _Integral>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR_AFTER_CXX14 _Integral
+__algo_gcd(_Integral __x, _Integral __y)
+{
+    do
+    {
+        _Integral __t = __x % __y;
+        __x = __y;
+        __y = __t;
+    } while (__y);
+    return __x;
+}
+
+template<typename _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX14 _RandomAccessIterator
+__rotate_gcd(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+
+    const difference_type __m1 = __middle - __first;
+    const difference_type __m2 = __last - __middle;
+    if (__m1 == __m2)
+    {
+        _VSTD::swap_ranges(__first, __middle, __middle);
+        return __middle;
+    }
+    const difference_type __g = _VSTD::__algo_gcd(__m1, __m2);
+    for (_RandomAccessIterator __p = __first + __g; __p != __first;)
+    {
+        value_type __t(_VSTD::move(*--__p));
+        _RandomAccessIterator __p1 = __p;
+        _RandomAccessIterator __p2 = __p1 + __m1;
+        do
+        {
+            *__p1 = _VSTD::move(*__p2);
+            __p1 = __p2;
+            const difference_type __d = __last - __p2;
+            if (__m1 < __d)
+                __p2 += __m1;
+            else
+                __p2 = __first + (__m1 - __d);
+        } while (__p2 != __p);
+        *__p1 = _VSTD::move(__t);
+    }
+    return __first + __m2;
+}
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator
+__rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
+         _VSTD::forward_iterator_tag)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+    if (is_trivially_move_assignable<value_type>::value)
+    {
+        if (_VSTD::next(__first) == __middle)
+            return _VSTD::__rotate_left(__first, __last);
+    }
+    return _VSTD::__rotate_forward(__first, __middle, __last);
+}
+
+template <class _BidirectionalIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _BidirectionalIterator
+__rotate(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
+         bidirectional_iterator_tag)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    if (is_trivially_move_assignable<value_type>::value)
+    {
+        if (_VSTD::next(__first) == __middle)
+            return _VSTD::__rotate_left(__first, __last);
+        if (_VSTD::next(__middle) == __last)
+            return _VSTD::__rotate_right(__first, __last);
+    }
+    return _VSTD::__rotate_forward(__first, __middle, __last);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator
+__rotate(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
+         random_access_iterator_tag)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    if (is_trivially_move_assignable<value_type>::value)
+    {
+        if (_VSTD::next(__first) == __middle)
+            return _VSTD::__rotate_left(__first, __last);
+        if (_VSTD::next(__middle) == __last)
+            return _VSTD::__rotate_right(__first, __last);
+        return _VSTD::__rotate_gcd(__first, __middle, __last);
+    }
+    return _VSTD::__rotate_forward(__first, __middle, __last);
+}
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
+{
+    if (__first == __middle)
+        return __last;
+    if (__middle == __last)
+        return __first;
+    return _VSTD::__rotate(__first, __middle, __last,
+                           typename iterator_traits<_ForwardIterator>::iterator_category());
+}
+
+// rotate_copy
+
+template <class _ForwardIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+rotate_copy(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last, _OutputIterator __result)
+{
+    return _VSTD::copy(__first, __middle, _VSTD::copy(__middle, __last, __result));
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_ROTATE_H

libcxx/include/__algorithm/sample.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SAMPLE_H
+#define _LIBCPP___ALGORITHM_SAMPLE_H
+
+#include <__config>
+#include <__algorithm/min.h>
+#include <__algorithm/uniform_int_distribution.h>
+#include <iterator>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _PopulationIterator, class _SampleIterator, class _Distance,
+          class _UniformRandomNumberGenerator>
+_LIBCPP_INLINE_VISIBILITY
+_SampleIterator __sample(_PopulationIterator __first,
+                         _PopulationIterator __last, _SampleIterator __output_iter,
+                         _Distance __n,
+                         _UniformRandomNumberGenerator & __g,
+                         input_iterator_tag) {
+
+  _Distance __k = 0;
+  for (; __first != __last && __k < __n; ++__first, (void) ++__k)
+    __output_iter[__k] = *__first;
+  _Distance __sz = __k;
+  for (; __first != __last; ++__first, (void) ++__k) {
+    _Distance __r = uniform_int_distribution<_Distance>(0, __k)(__g);
+    if (__r < __sz)
+      __output_iter[__r] = *__first;
+  }
+  return __output_iter + _VSTD::min(__n, __k);
+}
+
+template <class _PopulationIterator, class _SampleIterator, class _Distance,
+          class _UniformRandomNumberGenerator>
+_LIBCPP_INLINE_VISIBILITY
+_SampleIterator __sample(_PopulationIterator __first,
+                         _PopulationIterator __last, _SampleIterator __output_iter,
+                         _Distance __n,
+                         _UniformRandomNumberGenerator& __g,
+                         forward_iterator_tag) {
+  _Distance __unsampled_sz = _VSTD::distance(__first, __last);
+  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
+    _Distance __r = uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
+    if (__r < __n) {
+      *__output_iter++ = *__first;
+      --__n;
+    }
+  }
+  return __output_iter;
+}
+
+template <class _PopulationIterator, class _SampleIterator, class _Distance,
+          class _UniformRandomNumberGenerator>
+_LIBCPP_INLINE_VISIBILITY
+_SampleIterator __sample(_PopulationIterator __first,
+                         _PopulationIterator __last, _SampleIterator __output_iter,
+                         _Distance __n, _UniformRandomNumberGenerator& __g) {
+  typedef typename iterator_traits<_PopulationIterator>::iterator_category
+        _PopCategory;
+  typedef typename iterator_traits<_PopulationIterator>::difference_type
+        _Difference;
+  static_assert(__is_cpp17_forward_iterator<_PopulationIterator>::value ||
+                __is_cpp17_random_access_iterator<_SampleIterator>::value,
+                "SampleIterator must meet the requirements of RandomAccessIterator");
+  typedef typename common_type<_Distance, _Difference>::type _CommonType;
+  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
+  return _VSTD::__sample(
+      __first, __last, __output_iter, _CommonType(__n),
+      __g, _PopCategory());
+}
+
+#if _LIBCPP_STD_VER > 14
+template <class _PopulationIterator, class _SampleIterator, class _Distance,
+          class _UniformRandomNumberGenerator>
+inline _LIBCPP_INLINE_VISIBILITY
+_SampleIterator sample(_PopulationIterator __first,
+                       _PopulationIterator __last, _SampleIterator __output_iter,
+                       _Distance __n, _UniformRandomNumberGenerator&& __g) {
+    return _VSTD::__sample(__first, __last, __output_iter, __n, __g);
+}
+#endif // _LIBCPP_STD_VER > 14
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SAMPLE_H

libcxx/include/__algorithm/search.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SEARCH_H
+#define _LIBCPP___ALGORITHM_SEARCH_H
+
+#include <__config>
+#include <__functional/search.h>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
+search(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2,
+       _BinaryPredicate __pred) {
+  return _VSTD::__search<typename add_lvalue_reference<_BinaryPredicate>::type>(
+             __first1, __last1, __first2, __last2, __pred,
+             typename iterator_traits<_ForwardIterator1>::iterator_category(),
+             typename iterator_traits<_ForwardIterator2>::iterator_category())
+      .first;
+}
+
+template <class _ForwardIterator1, class _ForwardIterator2>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
+search(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
+  typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
+  typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
+  return _VSTD::search(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
+}
+
+#if _LIBCPP_STD_VER > 14
+template <class _ForwardIterator, class _Searcher>
+_LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher& __s) {
+  return __s(__f, __l).first;
+}
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SEARCH_H

libcxx/include/__algorithm/search_n.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SEARCH_N_H
+#define _LIBCPP___ALGORITHM_SEARCH_N_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _BinaryPredicate, class _ForwardIterator, class _Size, class _Tp>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator __search_n(_ForwardIterator __first, _ForwardIterator __last,
+                                                          _Size __count, const _Tp& __value_, _BinaryPredicate __pred,
+                                                          forward_iterator_tag) {
+  if (__count <= 0)
+    return __first;
+  while (true) {
+    // Find first element in sequence that matchs __value_, with a mininum of loop checks
+    while (true) {
+      if (__first == __last) // return __last if no element matches __value_
+        return __last;
+      if (__pred(*__first, __value_))
+        break;
+      ++__first;
+    }
+    // *__first matches __value_, now match elements after here
+    _ForwardIterator __m = __first;
+    _Size __c(0);
+    while (true) {
+      if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
+        return __first;
+      if (++__m == __last) // Otherwise if source exhaused, pattern not found
+        return __last;
+      if (!__pred(*__m, __value_)) // if there is a mismatch, restart with a new __first
+      {
+        __first = __m;
+        ++__first;
+        break;
+      } // else there is a match, check next elements
+    }
+  }
+}
+
+template <class _BinaryPredicate, class _RandomAccessIterator, class _Size, class _Tp>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator __search_n(_RandomAccessIterator __first,
+                                                               _RandomAccessIterator __last, _Size __count,
+                                                               const _Tp& __value_, _BinaryPredicate __pred,
+                                                               random_access_iterator_tag) {
+  if (__count <= 0)
+    return __first;
+  _Size __len = static_cast<_Size>(__last - __first);
+  if (__len < __count)
+    return __last;
+  const _RandomAccessIterator __s = __last - (__count - 1); // Start of pattern match can't go beyond here
+  while (true) {
+    // Find first element in sequence that matchs __value_, with a mininum of loop checks
+    while (true) {
+      if (__first >= __s) // return __last if no element matches __value_
+        return __last;
+      if (__pred(*__first, __value_))
+        break;
+      ++__first;
+    }
+    // *__first matches __value_, now match elements after here
+    _RandomAccessIterator __m = __first;
+    _Size __c(0);
+    while (true) {
+      if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
+        return __first;
+      ++__m;                       // no need to check range on __m because __s guarantees we have enough source
+      if (!__pred(*__m, __value_)) // if there is a mismatch, restart with a new __first
+      {
+        __first = __m;
+        ++__first;
+        break;
+      } // else there is a match, check next elements
+    }
+  }
+}
+
+template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator search_n(
+    _ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_, _BinaryPredicate __pred) {
+  return _VSTD::__search_n<typename add_lvalue_reference<_BinaryPredicate>::type>(
+      __first, __last, _VSTD::__convert_to_integral(__count), __value_, __pred,
+      typename iterator_traits<_ForwardIterator>::iterator_category());
+}
+
+template <class _ForwardIterator, class _Size, class _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_) {
+  typedef typename iterator_traits<_ForwardIterator>::value_type __v;
+  return _VSTD::search_n(__first, __last, _VSTD::__convert_to_integral(__count), __value_, __equal_to<__v, _Tp>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SEARCH_N_H

libcxx/include/__algorithm/set_difference.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SET_DIFFERENCE_H
+#define _LIBCPP___ALGORITHM_SET_DIFFERENCE_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/copy.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
+__set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
+                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    while (__first1 != __last1)
+    {
+        if (__first2 == __last2)
+            return _VSTD::copy(__first1, __last1, __result);
+        if (__comp(*__first1, *__first2))
+        {
+            *__result = *__first1;
+            ++__result;
+            ++__first1;
+        }
+        else
+        {
+            if (!__comp(*__first2, *__first1))
+                ++__first1;
+            ++__first2;
+        }
+    }
+    return __result;
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
+               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__set_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
+               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
+{
+    return _VSTD::set_difference(__first1, __last1, __first2, __last2, __result,
+                                __less<typename iterator_traits<_InputIterator1>::value_type,
+                                       typename iterator_traits<_InputIterator2>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SET_DIFFERENCE_H

libcxx/include/__algorithm/set_intersection.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SET_INTERSECTION_H
+#define _LIBCPP___ALGORITHM_SET_INTERSECTION_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
+__set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
+                   _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    while (__first1 != __last1 && __first2 != __last2)
+    {
+        if (__comp(*__first1, *__first2))
+            ++__first1;
+        else
+        {
+            if (!__comp(*__first2, *__first1))
+            {
+                *__result = *__first1;
+                ++__result;
+                ++__first1;
+            }
+            ++__first2;
+        }
+    }
+    return __result;
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
+                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__set_intersection<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
+                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
+{
+    return _VSTD::set_intersection(__first1, __last1, __first2, __last2, __result,
+                                  __less<typename iterator_traits<_InputIterator1>::value_type,
+                                         typename iterator_traits<_InputIterator2>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SET_INTERSECTION_H

libcxx/include/__algorithm/set_symmetric_difference.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SET_SYMMETRIC_DIFFERENCE_H
+#define _LIBCPP___ALGORITHM_SET_SYMMETRIC_DIFFERENCE_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/copy.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
+__set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
+                           _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    while (__first1 != __last1)
+    {
+        if (__first2 == __last2)
+            return _VSTD::copy(__first1, __last1, __result);
+        if (__comp(*__first1, *__first2))
+        {
+            *__result = *__first1;
+            ++__result;
+            ++__first1;
+        }
+        else
+        {
+            if (__comp(*__first2, *__first1))
+            {
+                *__result = *__first2;
+                ++__result;
+            }
+            else
+                ++__first1;
+            ++__first2;
+        }
+    }
+    return _VSTD::copy(__first2, __last2, __result);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
+                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__set_symmetric_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
+                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
+{
+    return _VSTD::set_symmetric_difference(__first1, __last1, __first2, __last2, __result,
+                                          __less<typename iterator_traits<_InputIterator1>::value_type,
+                                                 typename iterator_traits<_InputIterator2>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SET_SYMMETRIC_DIFFERENCE_H

libcxx/include/__algorithm/set_union.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SET_UNION_H
+#define _LIBCPP___ALGORITHM_SET_UNION_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/copy.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
+__set_union(_InputIterator1 __first1, _InputIterator1 __last1,
+            _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    for (; __first1 != __last1; ++__result)
+    {
+        if (__first2 == __last2)
+            return _VSTD::copy(__first1, __last1, __result);
+        if (__comp(*__first2, *__first1))
+        {
+            *__result = *__first2;
+            ++__first2;
+        }
+        else
+        {
+            if (!__comp(*__first1, *__first2))
+                ++__first2;
+            *__result = *__first1;
+            ++__first1;
+        }
+    }
+    return _VSTD::copy(__first2, __last2, __result);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_union(_InputIterator1 __first1, _InputIterator1 __last1,
+          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    return _VSTD::__set_union<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+set_union(_InputIterator1 __first1, _InputIterator1 __last1,
+          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
+{
+    return _VSTD::set_union(__first1, __last1, __first2, __last2, __result,
+                          __less<typename iterator_traits<_InputIterator1>::value_type,
+                                 typename iterator_traits<_InputIterator2>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SET_UNION_H

libcxx/include/__algorithm/shift.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SHIFT_H
+#define _LIBCPP___ALGORITHM_SHIFT_H
+
+#include <__config>
+#include <__algorithm/move.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// shift_left, shift_right
+
+#if _LIBCPP_STD_VER > 17
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY constexpr
+_ForwardIterator
+shift_left(_ForwardIterator __first, _ForwardIterator __last,
+           typename iterator_traits<_ForwardIterator>::difference_type __n)
+{
+    if (__n == 0) {
+        return __last;
+    }
+
+    _ForwardIterator __m = __first;
+    if constexpr (__is_cpp17_random_access_iterator<_ForwardIterator>::value) {
+        if (__n >= __last - __first) {
+            return __first;
+        }
+        __m += __n;
+    } else {
+        for (; __n > 0; --__n) {
+            if (__m == __last) {
+                return __first;
+            }
+            ++__m;
+        }
+    }
+    return _VSTD::move(__m, __last, __first);
+}
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY constexpr
+_ForwardIterator
+shift_right(_ForwardIterator __first, _ForwardIterator __last,
+            typename iterator_traits<_ForwardIterator>::difference_type __n)
+{
+    if (__n == 0) {
+        return __first;
+    }
+
+    if constexpr (__is_cpp17_random_access_iterator<_ForwardIterator>::value) {
+        decltype(__n) __d = __last - __first;
+        if (__n >= __d) {
+            return __last;
+        }
+        _ForwardIterator __m = __first + (__d - __n);
+        return _VSTD::move_backward(__first, __m, __last);
+    } else if constexpr (__is_cpp17_bidirectional_iterator<_ForwardIterator>::value) {
+        _ForwardIterator __m = __last;
+        for (; __n > 0; --__n) {
+            if (__m == __first) {
+                return __last;
+            }
+            --__m;
+        }
+        return _VSTD::move_backward(__first, __m, __last);
+    } else {
+        _ForwardIterator __ret = __first;
+        for (; __n > 0; --__n) {
+            if (__ret == __last) {
+                return __last;
+            }
+            ++__ret;
+        }
+
+        // We have an __n-element scratch space from __first to __ret.
+        // Slide an __n-element window [__trail, __lead) from left to right.
+        // We're essentially doing swap_ranges(__first, __ret, __trail, __lead)
+        // over and over; but once __lead reaches __last we needn't bother
+        // to save the values of elements [__trail, __last).
+
+        auto __trail = __first;
+        auto __lead = __ret;
+        while (__trail != __ret) {
+            if (__lead == __last) {
+                _VSTD::move(__first, __trail, __ret);
+                return __ret;
+            }
+            ++__trail;
+            ++__lead;
+        }
+
+        _ForwardIterator __mid = __first;
+        while (true) {
+            if (__lead == __last) {
+                __trail = _VSTD::move(__mid, __ret, __trail);
+                _VSTD::move(__first, __mid, __trail);
+                return __ret;
+            }
+            swap(*__mid, *__trail);
+            ++__mid;
+            ++__trail;
+            ++__lead;
+            if (__mid == __ret) {
+                __mid = __first;
+            }
+        }
+    }
+}
+
+#endif // _LIBCPP_STD_VER > 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SHIFT_H

libcxx/include/__algorithm/shuffle.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SHUFFLE_H
+#define _LIBCPP___ALGORITHM_SHUFFLE_H
+
+#include <__config>
+#include <__algorithm/uniform_int_distribution.h>
+#include <__iterator/iterator_traits.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE) \
+  || defined(_LIBCPP_BUILDING_LIBRARY)
+class _LIBCPP_TYPE_VIS __rs_default;
+
+_LIBCPP_FUNC_VIS __rs_default __rs_get();
+
+class _LIBCPP_TYPE_VIS __rs_default
+{
+    static unsigned __c_;
+
+    __rs_default();
+public:
+    typedef uint_fast32_t result_type;
+
+    static const result_type _Min = 0;
+    static const result_type _Max = 0xFFFFFFFF;
+
+    __rs_default(const __rs_default&);
+    ~__rs_default();
+
+    result_type operator()();
+
+    static _LIBCPP_CONSTEXPR result_type min() {return _Min;}
+    static _LIBCPP_CONSTEXPR result_type max() {return _Max;}
+
+    friend _LIBCPP_FUNC_VIS __rs_default __rs_get();
+};
+
+_LIBCPP_FUNC_VIS __rs_default __rs_get();
+
+template <class _RandomAccessIterator>
+_LIBCPP_DEPRECATED_IN_CXX14 void
+random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    typedef uniform_int_distribution<ptrdiff_t> _Dp;
+    typedef typename _Dp::param_type _Pp;
+    difference_type __d = __last - __first;
+    if (__d > 1)
+    {
+        _Dp __uid;
+        __rs_default __g = __rs_get();
+        for (--__last, (void) --__d; __first < __last; ++__first, (void) --__d)
+        {
+            difference_type __i = __uid(__g, _Pp(0, __d));
+            if (__i != difference_type(0))
+                swap(*__first, *(__first + __i));
+        }
+    }
+}
+
+template <class _RandomAccessIterator, class _RandomNumberGenerator>
+_LIBCPP_DEPRECATED_IN_CXX14 void
+random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
+#ifndef _LIBCPP_CXX03_LANG
+               _RandomNumberGenerator&& __rand)
+#else
+               _RandomNumberGenerator& __rand)
+#endif
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    difference_type __d = __last - __first;
+    if (__d > 1)
+    {
+        for (--__last; __first < __last; ++__first, (void) --__d)
+        {
+            difference_type __i = __rand(__d);
+            if (__i != difference_type(0))
+              swap(*__first, *(__first + __i));
+        }
+    }
+}
+#endif
+
+template<class _RandomAccessIterator, class _UniformRandomNumberGenerator>
+    void shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
+                 _UniformRandomNumberGenerator&& __g)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    typedef uniform_int_distribution<ptrdiff_t> _Dp;
+    typedef typename _Dp::param_type _Pp;
+    difference_type __d = __last - __first;
+    if (__d > 1)
+    {
+        _Dp __uid;
+        for (--__last, (void) --__d; __first < __last; ++__first, (void) --__d)
+        {
+            difference_type __i = __uid(__g, _Pp(0, __d));
+            if (__i != difference_type(0))
+                swap(*__first, *(__first + __i));
+        }
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SHUFFLE_H

libcxx/include/__algorithm/sift_down.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SIFT_DOWN_H
+#define _LIBCPP___ALGORITHM_SIFT_DOWN_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 void
+__sift_down(_RandomAccessIterator __first, _RandomAccessIterator /*__last*/,
+            _Compare __comp,
+            typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+            _RandomAccessIterator __start)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    // left-child of __start is at 2 * __start + 1
+    // right-child of __start is at 2 * __start + 2
+    difference_type __child = __start - __first;
+
+    if (__len < 2 || (__len - 2) / 2 < __child)
+        return;
+
+    __child = 2 * __child + 1;
+    _RandomAccessIterator __child_i = __first + __child;
+
+    if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
+        // right-child exists and is greater than left-child
+        ++__child_i;
+        ++__child;
+    }
+
+    // check if we are in heap-order
+    if (__comp(*__child_i, *__start))
+        // we are, __start is larger than it's largest child
+        return;
+
+    value_type __top(_VSTD::move(*__start));
+    do
+    {
+        // we are not in heap-order, swap the parent with its largest child
+        *__start = _VSTD::move(*__child_i);
+        __start = __child_i;
+
+        if ((__len - 2) / 2 < __child)
+            break;
+
+        // recompute the child based off of the updated parent
+        __child = 2 * __child + 1;
+        __child_i = __first + __child;
+
+        if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
+            // right-child exists and is greater than left-child
+            ++__child_i;
+            ++__child;
+        }
+
+        // check if we are in heap-order
+    } while (!__comp(*__child_i, __top));
+    *__start = _VSTD::move(__top);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SIFT_DOWN_H

libcxx/include/__algorithm/sort.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SORT_H
+#define _LIBCPP___ALGORITHM_SORT_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/comp.h>
+#include <__algorithm/min_element.h>
+#include <__algorithm/partial_sort.h>
+#include <__algorithm/unwrap_iter.h>
+#include <memory>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// stable, 2-3 compares, 0-2 swaps
+
+template <class _Compare, class _ForwardIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 unsigned
+__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
+{
+    unsigned __r = 0;
+    if (!__c(*__y, *__x))          // if x <= y
+    {
+        if (!__c(*__z, *__y))      // if y <= z
+            return __r;            // x <= y && y <= z
+                                   // x <= y && y > z
+        swap(*__y, *__z);          // x <= z && y < z
+        __r = 1;
+        if (__c(*__y, *__x))       // if x > y
+        {
+            swap(*__x, *__y);      // x < y && y <= z
+            __r = 2;
+        }
+        return __r;                // x <= y && y < z
+    }
+    if (__c(*__z, *__y))           // x > y, if y > z
+    {
+        swap(*__x, *__z);          // x < y && y < z
+        __r = 1;
+        return __r;
+    }
+    swap(*__x, *__y);              // x > y && y <= z
+    __r = 1;                       // x < y && x <= z
+    if (__c(*__z, *__y))           // if y > z
+    {
+        swap(*__y, *__z);          // x <= y && y < z
+        __r = 2;
+    }
+    return __r;
+}                                  // x <= y && y <= z
+
+// stable, 3-6 compares, 0-5 swaps
+
+template <class _Compare, class _ForwardIterator>
+unsigned
+__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
+            _ForwardIterator __x4, _Compare __c)
+{
+    unsigned __r = _VSTD::__sort3<_Compare>(__x1, __x2, __x3, __c);
+    if (__c(*__x4, *__x3))
+    {
+        swap(*__x3, *__x4);
+        ++__r;
+        if (__c(*__x3, *__x2))
+        {
+            swap(*__x2, *__x3);
+            ++__r;
+            if (__c(*__x2, *__x1))
+            {
+                swap(*__x1, *__x2);
+                ++__r;
+            }
+        }
+    }
+    return __r;
+}
+
+// stable, 4-10 compares, 0-9 swaps
+
+template <class _Compare, class _ForwardIterator>
+_LIBCPP_HIDDEN
+unsigned
+__sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
+            _ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
+{
+    unsigned __r = _VSTD::__sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
+    if (__c(*__x5, *__x4))
+    {
+        swap(*__x4, *__x5);
+        ++__r;
+        if (__c(*__x4, *__x3))
+        {
+            swap(*__x3, *__x4);
+            ++__r;
+            if (__c(*__x3, *__x2))
+            {
+                swap(*__x2, *__x3);
+                ++__r;
+                if (__c(*__x2, *__x1))
+                {
+                    swap(*__x1, *__x2);
+                    ++__r;
+                }
+            }
+        }
+    }
+    return __r;
+}
+
+// Assumes size > 0
+template <class _Compare, class _BidirectionalIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 void
+__selection_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
+{
+    _BidirectionalIterator __lm1 = __last;
+    for (--__lm1; __first != __lm1; ++__first)
+    {
+        _BidirectionalIterator __i = _VSTD::min_element<_BidirectionalIterator,
+                                                        typename add_lvalue_reference<_Compare>::type>
+                                                       (__first, __last, __comp);
+        if (__i != __first)
+            swap(*__first, *__i);
+    }
+}
+
+template <class _Compare, class _BidirectionalIterator>
+void
+__insertion_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    if (__first != __last)
+    {
+        _BidirectionalIterator __i = __first;
+        for (++__i; __i != __last; ++__i)
+        {
+            _BidirectionalIterator __j = __i;
+            value_type __t(_VSTD::move(*__j));
+            for (_BidirectionalIterator __k = __i; __k != __first && __comp(__t,  *--__k); --__j)
+                *__j = _VSTD::move(*__k);
+            *__j = _VSTD::move(__t);
+        }
+    }
+}
+
+template <class _Compare, class _RandomAccessIterator>
+void
+__insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    _RandomAccessIterator __j = __first+2;
+    _VSTD::__sort3<_Compare>(__first, __first+1, __j, __comp);
+    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
+    {
+        if (__comp(*__i, *__j))
+        {
+            value_type __t(_VSTD::move(*__i));
+            _RandomAccessIterator __k = __j;
+            __j = __i;
+            do
+            {
+                *__j = _VSTD::move(*__k);
+                __j = __k;
+            } while (__j != __first && __comp(__t, *--__k));
+            *__j = _VSTD::move(__t);
+        }
+        __j = __i;
+    }
+}
+
+template <class _Compare, class _RandomAccessIterator>
+bool
+__insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    switch (__last - __first)
+    {
+    case 0:
+    case 1:
+        return true;
+    case 2:
+        if (__comp(*--__last, *__first))
+            swap(*__first, *__last);
+        return true;
+    case 3:
+        _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
+        return true;
+    case 4:
+        _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
+        return true;
+    case 5:
+        _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
+        return true;
+    }
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    _RandomAccessIterator __j = __first+2;
+    _VSTD::__sort3<_Compare>(__first, __first+1, __j, __comp);
+    const unsigned __limit = 8;
+    unsigned __count = 0;
+    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
+    {
+        if (__comp(*__i, *__j))
+        {
+            value_type __t(_VSTD::move(*__i));
+            _RandomAccessIterator __k = __j;
+            __j = __i;
+            do
+            {
+                *__j = _VSTD::move(*__k);
+                __j = __k;
+            } while (__j != __first && __comp(__t, *--__k));
+            *__j = _VSTD::move(__t);
+            if (++__count == __limit)
+                return ++__i == __last;
+        }
+        __j = __i;
+    }
+    return true;
+}
+
+template <class _Compare, class _BidirectionalIterator>
+void
+__insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
+                      typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    if (__first1 != __last1)
+    {
+        __destruct_n __d(0);
+        unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
+        value_type* __last2 = __first2;
+        ::new ((void*)__last2) value_type(_VSTD::move(*__first1));
+        __d.template __incr<value_type>();
+        for (++__last2; ++__first1 != __last1; ++__last2)
+        {
+            value_type* __j2 = __last2;
+            value_type* __i2 = __j2;
+            if (__comp(*__first1, *--__i2))
+            {
+                ::new ((void*)__j2) value_type(_VSTD::move(*__i2));
+                __d.template __incr<value_type>();
+                for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
+                    *__j2 = _VSTD::move(*__i2);
+                *__j2 = _VSTD::move(*__first1);
+            }
+            else
+            {
+                ::new ((void*)__j2) value_type(_VSTD::move(*__first1));
+                __d.template __incr<value_type>();
+            }
+        }
+        __h.release();
+    }
+}
+
+template <class _Compare, class _RandomAccessIterator>
+void
+__sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
+                                    is_trivially_copy_assignable<value_type>::value ? 30 : 6;
+    while (true)
+    {
+    __restart:
+        difference_type __len = __last - __first;
+        switch (__len)
+        {
+        case 0:
+        case 1:
+            return;
+        case 2:
+            if (__comp(*--__last, *__first))
+                swap(*__first, *__last);
+            return;
+        case 3:
+            _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
+            return;
+        case 4:
+            _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
+            return;
+        case 5:
+            _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
+            return;
+        }
+        if (__len <= __limit)
+        {
+            _VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
+            return;
+        }
+        // __len > 5
+        _RandomAccessIterator __m = __first;
+        _RandomAccessIterator __lm1 = __last;
+        --__lm1;
+        unsigned __n_swaps;
+        {
+        difference_type __delta;
+        if (__len >= 1000)
+        {
+            __delta = __len/2;
+            __m += __delta;
+            __delta /= 2;
+            __n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
+        }
+        else
+        {
+            __delta = __len/2;
+            __m += __delta;
+            __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
+        }
+        }
+        // *__m is median
+        // partition [__first, __m) < *__m and *__m <= [__m, __last)
+        // (this inhibits tossing elements equivalent to __m around unnecessarily)
+        _RandomAccessIterator __i = __first;
+        _RandomAccessIterator __j = __lm1;
+        // j points beyond range to be tested, *__m is known to be <= *__lm1
+        // The search going up is known to be guarded but the search coming down isn't.
+        // Prime the downward search with a guard.
+        if (!__comp(*__i, *__m))  // if *__first == *__m
+        {
+            // *__first == *__m, *__first doesn't go in first part
+            // manually guard downward moving __j against __i
+            while (true)
+            {
+                if (__i == --__j)
+                {
+                    // *__first == *__m, *__m <= all other elements
+                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
+                    ++__i;  // __first + 1
+                    __j = __last;
+                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
+                    {
+                        while (true)
+                        {
+                            if (__i == __j)
+                                return;  // [__first, __last) all equivalent elements
+                            if (__comp(*__first, *__i))
+                            {
+                                swap(*__i, *__j);
+                                ++__n_swaps;
+                                ++__i;
+                                break;
+                            }
+                            ++__i;
+                        }
+                    }
+                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
+                    if (__i == __j)
+                        return;
+                    while (true)
+                    {
+                        while (!__comp(*__first, *__i))
+                            ++__i;
+                        while (__comp(*__first, *--__j))
+                            ;
+                        if (__i >= __j)
+                            break;
+                        swap(*__i, *__j);
+                        ++__n_swaps;
+                        ++__i;
+                    }
+                    // [__first, __i) == *__first and *__first < [__i, __last)
+                    // The first part is sorted, sort the second part
+                    // _VSTD::__sort<_Compare>(__i, __last, __comp);
+                    __first = __i;
+                    goto __restart;
+                }
+                if (__comp(*__j, *__m))
+                {
+                    swap(*__i, *__j);
+                    ++__n_swaps;
+                    break;  // found guard for downward moving __j, now use unguarded partition
+                }
+            }
+        }
+        // It is known that *__i < *__m
+        ++__i;
+        // j points beyond range to be tested, *__m is known to be <= *__lm1
+        // if not yet partitioned...
+        if (__i < __j)
+        {
+            // known that *(__i - 1) < *__m
+            // known that __i <= __m
+            while (true)
+            {
+                // __m still guards upward moving __i
+                while (__comp(*__i, *__m))
+                    ++__i;
+                // It is now known that a guard exists for downward moving __j
+                while (!__comp(*--__j, *__m))
+                    ;
+                if (__i > __j)
+                    break;
+                swap(*__i, *__j);
+                ++__n_swaps;
+                // It is known that __m != __j
+                // If __m just moved, follow it
+                if (__m == __i)
+                    __m = __j;
+                ++__i;
+            }
+        }
+        // [__first, __i) < *__m and *__m <= [__i, __last)
+        if (__i != __m && __comp(*__m, *__i))
+        {
+            swap(*__i, *__m);
+            ++__n_swaps;
+        }
+        // [__first, __i) < *__i and *__i <= [__i+1, __last)
+        // If we were given a perfect partition, see if insertion sort is quick...
+        if (__n_swaps == 0)
+        {
+            bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
+            if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+1, __last, __comp))
+            {
+                if (__fs)
+                    return;
+                __last = __i;
+                continue;
+            }
+            else
+            {
+                if (__fs)
+                {
+                    __first = ++__i;
+                    continue;
+                }
+            }
+        }
+        // sort smaller range with recursive call and larger with tail recursion elimination
+        if (__i - __first < __last - __i)
+        {
+            _VSTD::__sort<_Compare>(__first, __i, __comp);
+            // _VSTD::__sort<_Compare>(__i+1, __last, __comp);
+            __first = ++__i;
+        }
+        else
+        {
+            _VSTD::__sort<_Compare>(__i+1, __last, __comp);
+            // _VSTD::__sort<_Compare>(__first, __i, __comp);
+            __last = __i;
+        }
+    }
+}
+
+template <class _Compare, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+__sort(_Tp** __first, _Tp** __last, __less<_Tp*>&)
+{
+    __less<uintptr_t> __comp;
+    _VSTD::__sort<__less<uintptr_t>&, uintptr_t*>((uintptr_t*)__first, (uintptr_t*)__last, __comp);
+}
+
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
+
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
+
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&))
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    if (__libcpp_is_constant_evaluated()) {
+        _VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
+    } else {
+        _VSTD::__sort<_Comp_ref>(_VSTD::__unwrap_iter(__first), _VSTD::__unwrap_iter(__last), _Comp_ref(__comp));
+    }
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SORT_H

libcxx/include/__algorithm/sort_heap.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_SORT_HEAP_H
+#define _LIBCPP___ALGORITHM_SORT_HEAP_H
+
+#include <__config>
+#include <__algorithm/pop_heap.h>
+#include <__algorithm/comp_ref_type.h>
+#include <__iterator/iterator_traits.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _RandomAccessIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 void
+__sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    for (difference_type __n = __last - __first; __n > 1; --__last, (void) --__n)
+        _VSTD::__pop_heap<_Compare>(__first, __last, __comp, __n);
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__sort_heap<_Comp_ref>(__first, __last, __comp);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    _VSTD::sort_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SORT_HEAP_H

libcxx/include/__algorithm/stable_partition.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_STABLE_PARTITION_H
+#define _LIBCPP___ALGORITHM_STABLE_PARTITION_H
+
+#include <__config>
+#include <__algorithm/rotate.h>
+#include <__iterator/iterator_traits.h>
+#include <memory>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Predicate, class _ForwardIterator, class _Distance, class _Pair>
+_ForwardIterator
+__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
+                   _Distance __len, _Pair __p, forward_iterator_tag __fit)
+{
+    // *__first is known to be false
+    // __len >= 1
+    if (__len == 1)
+        return __first;
+    if (__len == 2)
+    {
+        _ForwardIterator __m = __first;
+        if (__pred(*++__m))
+        {
+            swap(*__first, *__m);
+            return __m;
+        }
+        return __first;
+    }
+    if (__len <= __p.second)
+    {   // The buffer is big enough to use
+        typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+        __destruct_n __d(0);
+        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
+        // Move the falses into the temporary buffer, and the trues to the front of the line
+        // Update __first to always point to the end of the trues
+        value_type* __t = __p.first;
+        ::new ((void*)__t) value_type(_VSTD::move(*__first));
+        __d.template __incr<value_type>();
+        ++__t;
+        _ForwardIterator __i = __first;
+        while (++__i != __last)
+        {
+            if (__pred(*__i))
+            {
+                *__first = _VSTD::move(*__i);
+                ++__first;
+            }
+            else
+            {
+                ::new ((void*)__t) value_type(_VSTD::move(*__i));
+                __d.template __incr<value_type>();
+                ++__t;
+            }
+        }
+        // All trues now at start of range, all falses in buffer
+        // Move falses back into range, but don't mess up __first which points to first false
+        __i = __first;
+        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, (void) ++__i)
+            *__i = _VSTD::move(*__t2);
+        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
+        return __first;
+    }
+    // Else not enough buffer, do in place
+    // __len >= 3
+    _ForwardIterator __m = __first;
+    _Distance __len2 = __len / 2;  // __len2 >= 2
+    _VSTD::advance(__m, __len2);
+    // recurse on [__first, __m), *__first know to be false
+    // F?????????????????
+    // f       m         l
+    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
+    _ForwardIterator __first_false = _VSTD::__stable_partition<_PredRef>(__first, __m, __pred, __len2, __p, __fit);
+    // TTTFFFFF??????????
+    // f  ff   m         l
+    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
+    _ForwardIterator __m1 = __m;
+    _ForwardIterator __second_false = __last;
+    _Distance __len_half = __len - __len2;
+    while (__pred(*__m1))
+    {
+        if (++__m1 == __last)
+            goto __second_half_done;
+        --__len_half;
+    }
+    // TTTFFFFFTTTF??????
+    // f  ff   m  m1     l
+    __second_false = _VSTD::__stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __fit);
+__second_half_done:
+    // TTTFFFFFTTTTTFFFFF
+    // f  ff   m    sf   l
+    return _VSTD::rotate(__first_false, __m, __second_false);
+    // TTTTTTTTFFFFFFFFFF
+    //         |
+}
+
+template <class _Predicate, class _ForwardIterator>
+_ForwardIterator
+__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
+                   forward_iterator_tag)
+{
+    const unsigned __alloc_limit = 3;  // might want to make this a function of trivial assignment
+    // Either prove all true and return __first or point to first false
+    while (true)
+    {
+        if (__first == __last)
+            return __first;
+        if (!__pred(*__first))
+            break;
+        ++__first;
+    }
+    // We now have a reduced range [__first, __last)
+    // *__first is known to be false
+    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+    difference_type __len = _VSTD::distance(__first, __last);
+    pair<value_type*, ptrdiff_t> __p(0, 0);
+    unique_ptr<value_type, __return_temporary_buffer> __h;
+    if (__len >= __alloc_limit)
+    {
+        __p = _VSTD::get_temporary_buffer<value_type>(__len);
+        __h.reset(__p.first);
+    }
+    return _VSTD::__stable_partition<typename add_lvalue_reference<_Predicate>::type>
+                             (__first, __last, __pred, __len, __p, forward_iterator_tag());
+}
+
+template <class _Predicate, class _BidirectionalIterator, class _Distance, class _Pair>
+_BidirectionalIterator
+__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
+                   _Distance __len, _Pair __p, bidirectional_iterator_tag __bit)
+{
+    // *__first is known to be false
+    // *__last is known to be true
+    // __len >= 2
+    if (__len == 2)
+    {
+        swap(*__first, *__last);
+        return __last;
+    }
+    if (__len == 3)
+    {
+        _BidirectionalIterator __m = __first;
+        if (__pred(*++__m))
+        {
+            swap(*__first, *__m);
+            swap(*__m, *__last);
+            return __last;
+        }
+        swap(*__m, *__last);
+        swap(*__first, *__m);
+        return __m;
+    }
+    if (__len <= __p.second)
+    {   // The buffer is big enough to use
+        typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+        __destruct_n __d(0);
+        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
+        // Move the falses into the temporary buffer, and the trues to the front of the line
+        // Update __first to always point to the end of the trues
+        value_type* __t = __p.first;
+        ::new ((void*)__t) value_type(_VSTD::move(*__first));
+        __d.template __incr<value_type>();
+        ++__t;
+        _BidirectionalIterator __i = __first;
+        while (++__i != __last)
+        {
+            if (__pred(*__i))
+            {
+                *__first = _VSTD::move(*__i);
+                ++__first;
+            }
+            else
+            {
+                ::new ((void*)__t) value_type(_VSTD::move(*__i));
+                __d.template __incr<value_type>();
+                ++__t;
+            }
+        }
+        // move *__last, known to be true
+        *__first = _VSTD::move(*__i);
+        __i = ++__first;
+        // All trues now at start of range, all falses in buffer
+        // Move falses back into range, but don't mess up __first which points to first false
+        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, (void) ++__i)
+            *__i = _VSTD::move(*__t2);
+        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
+        return __first;
+    }
+    // Else not enough buffer, do in place
+    // __len >= 4
+    _BidirectionalIterator __m = __first;
+    _Distance __len2 = __len / 2;  // __len2 >= 2
+    _VSTD::advance(__m, __len2);
+    // recurse on [__first, __m-1], except reduce __m-1 until *(__m-1) is true, *__first know to be false
+    // F????????????????T
+    // f       m        l
+    _BidirectionalIterator __m1 = __m;
+    _BidirectionalIterator __first_false = __first;
+    _Distance __len_half = __len2;
+    while (!__pred(*--__m1))
+    {
+        if (__m1 == __first)
+            goto __first_half_done;
+        --__len_half;
+    }
+    // F???TFFF?????????T
+    // f   m1  m        l
+    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
+    __first_false = _VSTD::__stable_partition<_PredRef>(__first, __m1, __pred, __len_half, __p, __bit);
+__first_half_done:
+    // TTTFFFFF?????????T
+    // f  ff   m        l
+    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
+    __m1 = __m;
+    _BidirectionalIterator __second_false = __last;
+    ++__second_false;
+    __len_half = __len - __len2;
+    while (__pred(*__m1))
+    {
+        if (++__m1 == __last)
+            goto __second_half_done;
+        --__len_half;
+    }
+    // TTTFFFFFTTTF?????T
+    // f  ff   m  m1    l
+    __second_false = _VSTD::__stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __bit);
+__second_half_done:
+    // TTTFFFFFTTTTTFFFFF
+    // f  ff   m    sf  l
+    return _VSTD::rotate(__first_false, __m, __second_false);
+    // TTTTTTTTFFFFFFFFFF
+    //         |
+}
+
+template <class _Predicate, class _BidirectionalIterator>
+_BidirectionalIterator
+__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
+                   bidirectional_iterator_tag)
+{
+    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
+    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
+    const difference_type __alloc_limit = 4;  // might want to make this a function of trivial assignment
+    // Either prove all true and return __first or point to first false
+    while (true)
+    {
+        if (__first == __last)
+            return __first;
+        if (!__pred(*__first))
+            break;
+        ++__first;
+    }
+    // __first points to first false, everything prior to __first is already set.
+    // Either prove [__first, __last) is all false and return __first, or point __last to last true
+    do
+    {
+        if (__first == --__last)
+            return __first;
+    } while (!__pred(*__last));
+    // We now have a reduced range [__first, __last]
+    // *__first is known to be false
+    // *__last is known to be true
+    // __len >= 2
+    difference_type __len = _VSTD::distance(__first, __last) + 1;
+    pair<value_type*, ptrdiff_t> __p(0, 0);
+    unique_ptr<value_type, __return_temporary_buffer> __h;
+    if (__len >= __alloc_limit)
+    {
+        __p = _VSTD::get_temporary_buffer<value_type>(__len);
+        __h.reset(__p.first);
+    }
+    return _VSTD::__stable_partition<typename add_lvalue_reference<_Predicate>::type>
+                             (__first, __last, __pred, __len, __p, bidirectional_iterator_tag());
+}
+
+template <class _ForwardIterator, class _Predicate>
+inline _LIBCPP_INLINE_VISIBILITY
+_ForwardIterator
+stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
+{
+    return _VSTD::__stable_partition<typename add_lvalue_reference<_Predicate>::type>
+                             (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_STABLE_PARTITION_H

libcxx/include/__algorithm/stable_sort.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_STABLE_SORT_H
+#define _LIBCPP___ALGORITHM_STABLE_SORT_H
+
+#include <__config>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/sort.h>
+#include <__algorithm/inplace_merge.h>
+#include <__iterator/iterator_traits.h>
+#include <memory>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _InputIterator1, class _InputIterator2>
+void
+__merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
+        _InputIterator2 __first2, _InputIterator2 __last2,
+        typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
+{
+    typedef typename iterator_traits<_InputIterator1>::value_type value_type;
+    __destruct_n __d(0);
+    unique_ptr<value_type, __destruct_n&> __h(__result, __d);
+    for (; true; ++__result)
+    {
+        if (__first1 == __last1)
+        {
+            for (; __first2 != __last2; ++__first2, ++__result, (void)__d.template __incr<value_type>())
+                ::new ((void*)__result) value_type(_VSTD::move(*__first2));
+            __h.release();
+            return;
+        }
+        if (__first2 == __last2)
+        {
+            for (; __first1 != __last1; ++__first1, ++__result, (void)__d.template __incr<value_type>())
+                ::new ((void*)__result) value_type(_VSTD::move(*__first1));
+            __h.release();
+            return;
+        }
+        if (__comp(*__first2, *__first1))
+        {
+            ::new ((void*)__result) value_type(_VSTD::move(*__first2));
+            __d.template __incr<value_type>();
+            ++__first2;
+        }
+        else
+        {
+            ::new ((void*)__result) value_type(_VSTD::move(*__first1));
+            __d.template __incr<value_type>();
+            ++__first1;
+        }
+    }
+}
+
+template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
+void
+__merge_move_assign(_InputIterator1 __first1, _InputIterator1 __last1,
+        _InputIterator2 __first2, _InputIterator2 __last2,
+        _OutputIterator __result, _Compare __comp)
+{
+    for (; __first1 != __last1; ++__result)
+    {
+        if (__first2 == __last2)
+        {
+            for (; __first1 != __last1; ++__first1, (void) ++__result)
+                *__result = _VSTD::move(*__first1);
+            return;
+        }
+        if (__comp(*__first2, *__first1))
+        {
+            *__result = _VSTD::move(*__first2);
+            ++__first2;
+        }
+        else
+        {
+            *__result = _VSTD::move(*__first1);
+            ++__first1;
+        }
+    }
+    for (; __first2 != __last2; ++__first2, (void) ++__result)
+        *__result = _VSTD::move(*__first2);
+}
+
+template <class _Compare, class _RandomAccessIterator>
+void
+__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
+              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size);
+
+template <class _Compare, class _RandomAccessIterator>
+void
+__stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Compare __comp,
+                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+                   typename iterator_traits<_RandomAccessIterator>::value_type* __first2)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    switch (__len)
+    {
+    case 0:
+        return;
+    case 1:
+        ::new ((void*)__first2) value_type(_VSTD::move(*__first1));
+        return;
+    case 2:
+        __destruct_n __d(0);
+        unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
+        if (__comp(*--__last1, *__first1))
+        {
+            ::new ((void*)__first2) value_type(_VSTD::move(*__last1));
+            __d.template __incr<value_type>();
+            ++__first2;
+            ::new ((void*)__first2) value_type(_VSTD::move(*__first1));
+        }
+        else
+        {
+            ::new ((void*)__first2) value_type(_VSTD::move(*__first1));
+            __d.template __incr<value_type>();
+            ++__first2;
+            ::new ((void*)__first2) value_type(_VSTD::move(*__last1));
+        }
+        __h2.release();
+        return;
+    }
+    if (__len <= 8)
+    {
+        _VSTD::__insertion_sort_move<_Compare>(__first1, __last1, __first2, __comp);
+        return;
+    }
+    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
+    _RandomAccessIterator __m = __first1 + __l2;
+    _VSTD::__stable_sort<_Compare>(__first1, __m, __comp, __l2, __first2, __l2);
+    _VSTD::__stable_sort<_Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
+    _VSTD::__merge_move_construct<_Compare>(__first1, __m, __m, __last1, __first2, __comp);
+}
+
+template <class _Tp>
+struct __stable_sort_switch
+{
+    static const unsigned value = 128*is_trivially_copy_assignable<_Tp>::value;
+};
+
+template <class _Compare, class _RandomAccessIterator>
+void
+__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
+              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    switch (__len)
+    {
+    case 0:
+    case 1:
+        return;
+    case 2:
+        if (__comp(*--__last, *__first))
+            swap(*__first, *__last);
+        return;
+    }
+    if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value))
+    {
+        _VSTD::__insertion_sort<_Compare>(__first, __last, __comp);
+        return;
+    }
+    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
+    _RandomAccessIterator __m = __first + __l2;
+    if (__len <= __buff_size)
+    {
+        __destruct_n __d(0);
+        unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
+        _VSTD::__stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
+        __d.__set(__l2, (value_type*)nullptr);
+        _VSTD::__stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
+        __d.__set(__len, (value_type*)nullptr);
+        _VSTD::__merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
+//         _VSTD::__merge<_Compare>(move_iterator<value_type*>(__buff),
+//                                  move_iterator<value_type*>(__buff + __l2),
+//                                  move_iterator<_RandomAccessIterator>(__buff + __l2),
+//                                  move_iterator<_RandomAccessIterator>(__buff + __len),
+//                                  __first, __comp);
+        return;
+    }
+    _VSTD::__stable_sort<_Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
+    _VSTD::__stable_sort<_Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
+    _VSTD::__inplace_merge<_Compare>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
+}
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
+    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
+    difference_type __len = __last - __first;
+    pair<value_type*, ptrdiff_t> __buf(0, 0);
+    unique_ptr<value_type, __return_temporary_buffer> __h;
+    if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value))
+    {
+        __buf = _VSTD::get_temporary_buffer<value_type>(__len);
+        __h.reset(__buf.first);
+    }
+    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+    _VSTD::__stable_sort<_Comp_ref>(__first, __last, __comp, __len, __buf.first, __buf.second);
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+    _VSTD::stable_sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_STABLE_SORT_H

libcxx/include/__algorithm/transform.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_TRANSFORM_H
+#define _LIBCPP___ALGORITHM_TRANSFORM_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _InputIterator, class _OutputIterator, class _UnaryOperation>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+transform(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _UnaryOperation __op)
+{
+    for (; __first != __last; ++__first, (void) ++__result)
+        *__result = __op(*__first);
+    return __result;
+}
+
+template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _BinaryOperation>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+transform(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2,
+          _OutputIterator __result, _BinaryOperation __binary_op)
+{
+    for (; __first1 != __last1; ++__first1, (void) ++__first2, ++__result)
+        *__result = __binary_op(*__first1, *__first2);
+    return __result;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_TRANSFORM_H

libcxx/include/__algorithm/uniform_int_distribution.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_UNIFORM_INT_DISTRIBUTION_H
+#define _LIBCPP___ALGORITHM_UNIFORM_INT_DISTRIBUTION_H
+
+#include <__config>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// __independent_bits_engine
+
+template <unsigned long long _Xp, size_t _Rp>
+struct __log2_imp
+{
+    static const size_t value = _Xp & ((unsigned long long)(1) << _Rp) ? _Rp
+                                           : __log2_imp<_Xp, _Rp - 1>::value;
+};
+
+template <unsigned long long _Xp>
+struct __log2_imp<_Xp, 0>
+{
+    static const size_t value = 0;
+};
+
+template <size_t _Rp>
+struct __log2_imp<0, _Rp>
+{
+    static const size_t value = _Rp + 1;
+};
+
+template <class _UIntType, _UIntType _Xp>
+struct __log2
+{
+    static const size_t value = __log2_imp<_Xp,
+                                         sizeof(_UIntType) * __CHAR_BIT__ - 1>::value;
+};
+
+template<class _Engine, class _UIntType>
+class __independent_bits_engine
+{
+public:
+    // types
+    typedef _UIntType result_type;
+
+private:
+    typedef typename _Engine::result_type _Engine_result_type;
+    typedef typename conditional
+        <
+            sizeof(_Engine_result_type) <= sizeof(result_type),
+                result_type,
+                _Engine_result_type
+        >::type _Working_result_type;
+
+    _Engine& __e_;
+    size_t __w_;
+    size_t __w0_;
+    size_t __n_;
+    size_t __n0_;
+    _Working_result_type __y0_;
+    _Working_result_type __y1_;
+    _Engine_result_type __mask0_;
+    _Engine_result_type __mask1_;
+
+#ifdef _LIBCPP_CXX03_LANG
+    static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
+                                          + _Working_result_type(1);
+#else
+    static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
+                                                      + _Working_result_type(1);
+#endif
+    static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
+    static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
+    static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
+
+public:
+    // constructors and seeding functions
+    __independent_bits_engine(_Engine& __e, size_t __w);
+
+    // generating functions
+    result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
+
+private:
+    result_type __eval(false_type);
+    result_type __eval(true_type);
+};
+
+template<class _Engine, class _UIntType>
+__independent_bits_engine<_Engine, _UIntType>
+    ::__independent_bits_engine(_Engine& __e, size_t __w)
+        : __e_(__e),
+          __w_(__w)
+{
+    __n_ = __w_ / __m + (__w_ % __m != 0);
+    __w0_ = __w_ / __n_;
+    if (_Rp == 0)
+        __y0_ = _Rp;
+    else if (__w0_ < _WDt)
+        __y0_ = (_Rp >> __w0_) << __w0_;
+    else
+        __y0_ = 0;
+    if (_Rp - __y0_ > __y0_ / __n_)
+    {
+        ++__n_;
+        __w0_ = __w_ / __n_;
+        if (__w0_ < _WDt)
+            __y0_ = (_Rp >> __w0_) << __w0_;
+        else
+            __y0_ = 0;
+    }
+    __n0_ = __n_ - __w_ % __n_;
+    if (__w0_ < _WDt - 1)
+        __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
+    else
+        __y1_ = 0;
+    __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) :
+                          _Engine_result_type(0);
+    __mask1_ = __w0_ < _EDt - 1 ?
+                               _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) :
+                               _Engine_result_type(~0);
+}
+
+template<class _Engine, class _UIntType>
+inline
+_UIntType
+__independent_bits_engine<_Engine, _UIntType>::__eval(false_type)
+{
+    return static_cast<result_type>(__e_() & __mask0_);
+}
+
+template<class _Engine, class _UIntType>
+_UIntType
+__independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
+{
+    const size_t _WRt = numeric_limits<result_type>::digits;
+    result_type _Sp = 0;
+    for (size_t __k = 0; __k < __n0_; ++__k)
+    {
+        _Engine_result_type __u;
+        do
+        {
+            __u = __e_() - _Engine::min();
+        } while (__u >= __y0_);
+        if (__w0_ < _WRt)
+            _Sp <<= __w0_;
+        else
+            _Sp = 0;
+        _Sp += __u & __mask0_;
+    }
+    for (size_t __k = __n0_; __k < __n_; ++__k)
+    {
+        _Engine_result_type __u;
+        do
+        {
+            __u = __e_() - _Engine::min();
+        } while (__u >= __y1_);
+        if (__w0_ < _WRt - 1)
+            _Sp <<= __w0_ + 1;
+        else
+            _Sp = 0;
+        _Sp += __u & __mask1_;
+    }
+    return _Sp;
+}
+
+template<class _IntType = int>
+class uniform_int_distribution
+{
+public:
+    // types
+    typedef _IntType result_type;
+
+    class param_type
+    {
+        result_type __a_;
+        result_type __b_;
+    public:
+        typedef uniform_int_distribution distribution_type;
+
+        explicit param_type(result_type __a = 0,
+                            result_type __b = numeric_limits<result_type>::max())
+            : __a_(__a), __b_(__b) {}
+
+        result_type a() const {return __a_;}
+        result_type b() const {return __b_;}
+
+        friend bool operator==(const param_type& __x, const param_type& __y)
+            {return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
+        friend bool operator!=(const param_type& __x, const param_type& __y)
+            {return !(__x == __y);}
+    };
+
+private:
+    param_type __p_;
+
+public:
+    // constructors and reset functions
+#ifndef _LIBCPP_CXX03_LANG
+    uniform_int_distribution() : uniform_int_distribution(0) {}
+    explicit uniform_int_distribution(
+        result_type __a, result_type __b = numeric_limits<result_type>::max())
+        : __p_(param_type(__a, __b)) {}
+#else
+    explicit uniform_int_distribution(
+        result_type __a = 0,
+        result_type __b = numeric_limits<result_type>::max())
+        : __p_(param_type(__a, __b)) {}
+#endif
+    explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
+    void reset() {}
+
+    // generating functions
+    template<class _URNG> result_type operator()(_URNG& __g)
+        {return (*this)(__g, __p_);}
+    template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
+
+    // property functions
+    result_type a() const {return __p_.a();}
+    result_type b() const {return __p_.b();}
+
+    param_type param() const {return __p_;}
+    void param(const param_type& __p) {__p_ = __p;}
+
+    result_type min() const {return a();}
+    result_type max() const {return b();}
+
+    friend bool operator==(const uniform_int_distribution& __x,
+                           const uniform_int_distribution& __y)
+        {return __x.__p_ == __y.__p_;}
+    friend bool operator!=(const uniform_int_distribution& __x,
+                           const uniform_int_distribution& __y)
+            {return !(__x == __y);}
+};
+
+template<class _IntType>
+template<class _URNG>
+typename uniform_int_distribution<_IntType>::result_type
+uniform_int_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
+_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+{
+    typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t),
+                                            uint32_t, uint64_t>::type _UIntType;
+    const _UIntType _Rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
+    if (_Rp == 1)
+        return __p.a();
+    const size_t _Dt = numeric_limits<_UIntType>::digits;
+    typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
+    if (_Rp == 0)
+        return static_cast<result_type>(_Eng(__g, _Dt)());
+    size_t __w = _Dt - __libcpp_clz(_Rp) - 1;
+    if ((_Rp & (numeric_limits<_UIntType>::max() >> (_Dt - __w))) != 0)
+        ++__w;
+    _Eng __e(__g, __w);
+    _UIntType __u;
+    do
+    {
+        __u = __e();
+    } while (__u >= _Rp);
+    return static_cast<result_type>(__u + __p.a());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_UNIFORM_INT_DISTRIBUTION_H

libcxx/include/__algorithm/unique.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_UNIQUE_H
+#define _LIBCPP___ALGORITHM_UNIQUE_H
+
+#include <__config>
+#include <__algorithm/adjacent_find.h>
+#include <__iterator/iterator_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// unique
+
+template <class _ForwardIterator, class _BinaryPredicate>
+_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
+{
+    __first = _VSTD::adjacent_find<_ForwardIterator, typename add_lvalue_reference<_BinaryPredicate>::type>
+                                 (__first, __last, __pred);
+    if (__first != __last)
+    {
+        // ...  a  a  ?  ...
+        //      f     i
+        _ForwardIterator __i = __first;
+        for (++__i; ++__i != __last;)
+            if (!__pred(*__first, *__i))
+                *++__first = _VSTD::move(*__i);
+        ++__first;
+    }
+    return __first;
+}
+
+template <class _ForwardIterator>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+unique(_ForwardIterator __first, _ForwardIterator __last)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
+    return _VSTD::unique(__first, __last, __equal_to<__v>());
+}
+
+// unique_copy
+
+template <class _BinaryPredicate, class _InputIterator, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
+__unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
+              input_iterator_tag, output_iterator_tag)
+{
+    if (__first != __last)
+    {
+        typename iterator_traits<_InputIterator>::value_type __t(*__first);
+        *__result = __t;
+        ++__result;
+        while (++__first != __last)
+        {
+            if (!__pred(__t, *__first))
+            {
+                __t = *__first;
+                *__result = __t;
+                ++__result;
+            }
+        }
+    }
+    return __result;
+}
+
+template <class _BinaryPredicate, class _ForwardIterator, class _OutputIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
+__unique_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
+              forward_iterator_tag, output_iterator_tag)
+{
+    if (__first != __last)
+    {
+        _ForwardIterator __i = __first;
+        *__result = *__i;
+        ++__result;
+        while (++__first != __last)
+        {
+            if (!__pred(*__i, *__first))
+            {
+                *__result = *__first;
+                ++__result;
+                __i = __first;
+            }
+        }
+    }
+    return __result;
+}
+
+template <class _BinaryPredicate, class _InputIterator, class _ForwardIterator>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+__unique_copy(_InputIterator __first, _InputIterator __last, _ForwardIterator __result, _BinaryPredicate __pred,
+              input_iterator_tag, forward_iterator_tag)
+{
+    if (__first != __last)
+    {
+        *__result = *__first;
+        while (++__first != __last)
+            if (!__pred(*__result, *__first))
+                *++__result = *__first;
+        ++__result;
+    }
+    return __result;
+}
+
+template <class _InputIterator, class _OutputIterator, class _BinaryPredicate>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred)
+{
+    return _VSTD::__unique_copy<typename add_lvalue_reference<_BinaryPredicate>::type>
+                              (__first, __last, __result, __pred,
+                               typename iterator_traits<_InputIterator>::iterator_category(),
+                               typename iterator_traits<_OutputIterator>::iterator_category());
+}
+
+template <class _InputIterator, class _OutputIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_OutputIterator
+unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
+{
+    typedef typename iterator_traits<_InputIterator>::value_type __v;
+    return _VSTD::unique_copy(__first, __last, __result, __equal_to<__v>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_UNIQUE_H

libcxx/include/__algorithm/unwrap_iter.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_UNWRAP_ITER_H
+#define _LIBCPP___ALGORITHM_UNWRAP_ITER_H
+
+#include <__config>
+#include <iterator>
+#include <__memory/pointer_traits.h>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// The job of __unwrap_iter is to lower contiguous iterators (such as
+// vector<T>::iterator) into pointers, to reduce the number of template
+// instantiations and to enable pointer-based optimizations e.g. in std::copy.
+// For iterators that are not contiguous, it must be a no-op.
+// In debug mode, we don't do this.
+//
+// __unwrap_iter is non-constexpr for user-defined iterators whose
+// `to_address` and/or `operator->` is non-constexpr. This is okay; but we
+// try to avoid doing __unwrap_iter in constant-evaluated contexts anyway.
+//
+// Some algorithms (e.g. std::copy, but not std::sort) need to convert an
+// "unwrapped" result back into a contiguous iterator. Since contiguous iterators
+// are random-access, we can do this portably using iterator arithmetic; this
+// is the job of __rewrap_iter.
+
+template <class _Iter, bool = __is_cpp17_contiguous_iterator<_Iter>::value>
+struct __unwrap_iter_impl {
+    static _LIBCPP_CONSTEXPR _Iter
+    __apply(_Iter __i) _NOEXCEPT {
+        return __i;
+    }
+};
+
+#if _LIBCPP_DEBUG_LEVEL < 2
+
+template <class _Iter>
+struct __unwrap_iter_impl<_Iter, true> {
+    static _LIBCPP_CONSTEXPR decltype(_VSTD::__to_address(declval<_Iter>()))
+    __apply(_Iter __i) _NOEXCEPT {
+        return _VSTD::__to_address(__i);
+    }
+};
+
+#endif // _LIBCPP_DEBUG_LEVEL < 2
+
+template<class _Iter, class _Impl = __unwrap_iter_impl<_Iter> >
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+decltype(_Impl::__apply(declval<_Iter>()))
+__unwrap_iter(_Iter __i) _NOEXCEPT
+{
+    return _Impl::__apply(__i);
+}
+
+template<class _OrigIter>
+_OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
+{
+    return __result;
+}
+
+template<class _OrigIter, class _UnwrappedIter>
+_OrigIter __rewrap_iter(_OrigIter __first, _UnwrappedIter __result)
+{
+    // Precondition: __result is reachable from __first
+    // Precondition: _OrigIter is a contiguous iterator
+    return __first + (__result - _VSTD::__unwrap_iter(__first));
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_UNWRAP_ITER_H

libcxx/include/__algorithm/upper_bound.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_UPPER_BOUND_H
+#define _LIBCPP___ALGORITHM_UPPER_BOUND_H
+
+#include <__config>
+#include <__algorithm/half_positive.h>
+#include <iterator>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Compare, class _ForwardIterator, class _Tp>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
+__upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
+    difference_type __len = _VSTD::distance(__first, __last);
+    while (__len != 0)
+    {
+        difference_type __l2 = _VSTD::__half_positive(__len);
+        _ForwardIterator __m = __first;
+        _VSTD::advance(__m, __l2);
+        if (__comp(__value_, *__m))
+            __len = __l2;
+        else
+        {
+            __first = ++__m;
+            __len -= __l2 + 1;
+        }
+    }
+    return __first;
+}
+
+template <class _ForwardIterator, class _Tp, class _Compare>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
+{
+    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
+    return _VSTD::__upper_bound<_Comp_ref>(__first, __last, __value_, __comp);
+}
+
+template <class _ForwardIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator
+upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
+{
+    return _VSTD::upper_bound(__first, __last, __value_,
+                             __less<_Tp, typename iterator_traits<_ForwardIterator>::value_type>());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_UPPER_BOUND_H

libcxx/include/__functional/search.h

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___FUNCTIONAL___SEARCH_H
+#define _LIBCPP___FUNCTIONAL___SEARCH_H
+
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <utility>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
+pair<_ForwardIterator1, _ForwardIterator1>
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 __search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
+                                           _ForwardIterator2 __first2, _ForwardIterator2 __last2,
+                                           _BinaryPredicate __pred, forward_iterator_tag, forward_iterator_tag) {
+  if (__first2 == __last2)
+    return _VSTD::make_pair(__first1, __first1); // Everything matches an empty sequence
+  while (true) {
+    // Find first element in sequence 1 that matchs *__first2, with a mininum of loop checks
+    while (true) {
+      if (__first1 == __last1) // return __last1 if no element matches *__first2
+        return _VSTD::make_pair(__last1, __last1);
+      if (__pred(*__first1, *__first2))
+        break;
+      ++__first1;
+    }
+    // *__first1 matches *__first2, now match elements after here
+    _ForwardIterator1 __m1 = __first1;
+    _ForwardIterator2 __m2 = __first2;
+    while (true) {
+      if (++__m2 == __last2) // If pattern exhausted, __first1 is the answer (works for 1 element pattern)
+        return _VSTD::make_pair(__first1, __m1);
+      if (++__m1 == __last1) // Otherwise if source exhaused, pattern not found
+        return _VSTD::make_pair(__last1, __last1);
+      if (!__pred(*__m1, *__m2)) // if there is a mismatch, restart with a new __first1
+      {
+        ++__first1;
+        break;
+      } // else there is a match, check next elements
+    }
+  }
+}
+
+template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 pair<_RandomAccessIterator1, _RandomAccessIterator1>
+__search(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
+         _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag,
+         random_access_iterator_tag) {
+  typedef typename iterator_traits<_RandomAccessIterator1>::difference_type _D1;
+  typedef typename iterator_traits<_RandomAccessIterator2>::difference_type _D2;
+  // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
+  const _D2 __len2 = __last2 - __first2;
+  if (__len2 == 0)
+    return _VSTD::make_pair(__first1, __first1);
+  const _D1 __len1 = __last1 - __first1;
+  if (__len1 < __len2)
+    return _VSTD::make_pair(__last1, __last1);
+  const _RandomAccessIterator1 __s = __last1 - (__len2 - 1); // Start of pattern match can't go beyond here
+
+  while (true) {
+    while (true) {
+      if (__first1 == __s)
+        return _VSTD::make_pair(__last1, __last1);
+      if (__pred(*__first1, *__first2))
+        break;
+      ++__first1;
+    }
+
+    _RandomAccessIterator1 __m1 = __first1;
+    _RandomAccessIterator2 __m2 = __first2;
+    while (true) {
+      if (++__m2 == __last2)
+        return _VSTD::make_pair(__first1, __first1 + __len2);
+      ++__m1; // no need to check range on __m1 because __s guarantees we have enough source
+      if (!__pred(*__m1, *__m2)) {
+        ++__first1;
+        break;
+      }
+    }
+  }
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___FUNCTIONAL___SEARCH_H

libcxx/include/__memory/temporary_buffer.h

 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 void return_temporary_buffer(_Tp* __p) _NOEXCEPT
 {
   _VSTD::__libcpp_deallocate_unsized((void*)__p, _LIBCPP_ALIGNOF(_Tp));
 }
 
+struct __return_temporary_buffer
+{
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
+};
+
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___MEMORY_TEMPORARY_BUFFER_H

libcxx/include/algorithm

 template <class BidirectionalIterator, class Compare>
     constexpr bool     // constexpr in C++20
     prev_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
 
 }  // std
 
 */
 
 #include <__config>
+#include <__debug>
 #include <__bits> // __libcpp_clz
 #include <cstddef>
 #include <cstring>
 #include <functional>
 #include <initializer_list>
+#include <utility> // needed to provide swap_ranges.
+#include <memory>
 #include <iterator>
 #include <memory>
 #include <type_traits>
 #include <utility> // swap_ranges
 #include <version>
 
-#include <__debug>
+#include <__algorithm/adjacent_find.h>
+#include <__algorithm/all_of.h>
+#include <__algorithm/any_of.h>
+#include <__algorithm/binary_search.h>
+#include <__algorithm/clamp.h>
+#include <__algorithm/comp.h>
+#include <__algorithm/comp_ref_type.h>
+#include <__algorithm/copy.h>
+#include <__algorithm/count.h>
+#include <__algorithm/count_if.h>
+#include <__algorithm/equal.h>
+#include <__algorithm/equal_range.h>
+#include <__algorithm/fill.h>
+#include <__algorithm/find.h>
+#include <__algorithm/find_end.h>
+#include <__algorithm/find_first_of.h>
+#include <__algorithm/find_if.h>
+#include <__algorithm/find_if_not.h>
+#include <__algorithm/for_each.h>
+#include <__algorithm/for_each_n.h>
+#include <__algorithm/generate.h>
+#include <__algorithm/half_positive.h>
+#include <__algorithm/includes.h>
+#include <__algorithm/inplace_merge.h>
+#include <__algorithm/is_heap.h>
+#include <__algorithm/is_heap_until.h>
+#include <__algorithm/is_partitioned.h>
+#include <__algorithm/is_permutation.h>
+#include <__algorithm/is_sorted.h>
+#include <__algorithm/lexicographical_compare.h>
+#include <__algorithm/lower_bound.h>
+#include <__algorithm/make_heap.h>
+#include <__algorithm/max.h>
+#include <__algorithm/max_element.h>
+#include <__algorithm/merge.h>
+#include <__algorithm/min.h>
+#include <__algorithm/min_element.h>
+#include <__algorithm/minmax.h>
+#include <__algorithm/minmax_element.h>
+#include <__algorithm/mismatch.h>
+#include <__algorithm/move.h>
+#include <__algorithm/next_permutation.h>
+#include <__algorithm/none_of.h>
+#include <__algorithm/nth_element.h>
+#include <__algorithm/partial_sort.h>
+#include <__algorithm/partition.h>
+#include <__algorithm/partition_point.h>
+#include <__algorithm/pop_heap.h>
+#include <__algorithm/prev_permutation.h>
+#include <__algorithm/push_heap.h>
+#include <__algorithm/remove.h>
+#include <__algorithm/replace.h>
+#include <__algorithm/reverse.h>
+#include <__algorithm/rotate.h>
+#include <__algorithm/sample.h>
+#include <__algorithm/search.h>
+#include <__algorithm/search_n.h>
+#include <__algorithm/set_difference.h>
+#include <__algorithm/set_intersection.h>
+#include <__algorithm/set_symmetric_difference.h>
+#include <__algorithm/set_union.h>
+#include <__algorithm/shift.h>
+#include <__algorithm/shuffle.h>
+#include <__algorithm/sift_down.h>
+#include <__algorithm/sort.h>
+#include <__algorithm/sort_heap.h>
+#include <__algorithm/stable_partition.h>
+#include <__algorithm/stable_sort.h>
+#include <__algorithm/transform.h>
+#include <__algorithm/uniform_int_distribution.h>
+#include <__algorithm/unique.h>
+#include <__algorithm/unwrap_iter.h>
+#include <__algorithm/upper_bound.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-// I'd like to replace these with _VSTD::equal_to<void>, but can't because:
-//   * That only works with C++14 and later, and
-//   * We haven't included <functional> here.
-template <class _T1, class _T2 = _T1>
-struct __equal_to
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T2& __y) const {return __x == __y;}
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T1& __y) const {return __x == __y;}
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T2& __y) const {return __x == __y;}
-};
-
-template <class _T1>
-struct __equal_to<_T1, _T1>
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
-};
-
-template <class _T1>
-struct __equal_to<const _T1, _T1>
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
-};
-
-template <class _T1>
-struct __equal_to<_T1, const _T1>
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
-};
-
-template <class _T1, class _T2 = _T1>
-struct __less
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
-};
-
-template <class _T1>
-struct __less<_T1, _T1>
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
-};
-
-template <class _T1>
-struct __less<const _T1, _T1>
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
-};
-
-template <class _T1>
-struct __less<_T1, const _T1>
-{
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
-};
-
-template <class _Predicate>
-class __invert // invert the sense of a comparison
-{
-private:
-    _Predicate __p_;
-public:
-    _LIBCPP_INLINE_VISIBILITY __invert() {}
-
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __invert(_Predicate __p) : __p_(__p) {}
-
-    template <class _T1>
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(const _T1& __x) {return !__p_(__x);}
-
-    template <class _T1, class _T2>
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
-};
-
-// Perform division by two quickly for positive integers (llvm.org/PR39129)
-
-template <typename _Integral>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-typename enable_if
-<
-    is_integral<_Integral>::value,
-    _Integral
->::type
-__half_positive(_Integral __value)
-{
-    return static_cast<_Integral>(static_cast<typename make_unsigned<_Integral>::type>(__value) / 2);
-}
-
-template <typename _Tp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-typename enable_if
-<
-    !is_integral<_Tp>::value,
-    _Tp
->::type
-__half_positive(_Tp __value)
-{
-    return __value / 2;
-}
-
-#ifdef _LIBCPP_DEBUG
-
-template <class _Compare>
-struct __debug_less
-{
-    _Compare &__comp_;
-    _LIBCPP_CONSTEXPR_AFTER_CXX17
-    __debug_less(_Compare& __c) : __comp_(__c) {}
-
-    template <class _Tp, class _Up>
-    _LIBCPP_CONSTEXPR_AFTER_CXX17
-    bool operator()(const _Tp& __x,  const _Up& __y)
-    {
-        bool __r = __comp_(__x, __y);
-        if (__r)
-            __do_compare_assert(0, __y, __x);
-        return __r;
-    }
-
-    template <class _Tp, class _Up>
-    _LIBCPP_CONSTEXPR_AFTER_CXX17
-    bool operator()(_Tp& __x,  _Up& __y)
-    {
-        bool __r = __comp_(__x, __y);
-        if (__r)
-            __do_compare_assert(0, __y, __x);
-        return __r;
-    }
-
-    template <class _LHS, class _RHS>
-    _LIBCPP_CONSTEXPR_AFTER_CXX17
-    inline _LIBCPP_INLINE_VISIBILITY
-    decltype((void)declval<_Compare&>()(
-        declval<_LHS &>(), declval<_RHS &>()))
-    __do_compare_assert(int, _LHS & __l, _RHS & __r) {
-        _LIBCPP_ASSERT(!__comp_(__l, __r),
-            "Comparator does not induce a strict weak ordering");
-    }
-
-    template <class _LHS, class _RHS>
-    _LIBCPP_CONSTEXPR_AFTER_CXX17
-    inline _LIBCPP_INLINE_VISIBILITY
-    void __do_compare_assert(long, _LHS &, _RHS &) {}
-};
-
-#endif // _LIBCPP_DEBUG
-
-template <class _Comp>
-struct __comp_ref_type {
-  // Pass the comparator by lvalue reference. Or in debug mode, using a
-  // debugging wrapper that stores a reference.
-#ifndef _LIBCPP_DEBUG
-  typedef typename add_lvalue_reference<_Comp>::type type;
-#else
-  typedef __debug_less<_Comp> type;
-#endif
-};
-
-// all_of
-
-template <class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-        if (!__pred(*__first))
-            return false;
-    return true;
-}
-
-// any_of
-
-template <class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-        if (__pred(*__first))
-            return true;
-    return false;
-}
-
-// none_of
-
-template <class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-        if (__pred(*__first))
-            return false;
-    return true;
-}
-
-// for_each
-
-template <class _InputIterator, class _Function>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_Function
-for_each(_InputIterator __first, _InputIterator __last, _Function __f)
-{
-    for (; __first != __last; ++__first)
-        __f(*__first);
-    return __f;
-}
-
-#if _LIBCPP_STD_VER > 14
-// for_each_n
-
-template <class _InputIterator, class _Size, class _Function>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_InputIterator
-for_each_n(_InputIterator __first, _Size __orig_n, _Function __f)
-{
-    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
-    _IntegralSize __n = __orig_n;
-    while (__n > 0)
-    {
-         __f(*__first);
-         ++__first;
-         --__n;
-    }
-    return __first;
-}
-#endif
-
-// find
-
-template <class _InputIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_InputIterator
-find(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
-{
-    for (; __first != __last; ++__first)
-        if (*__first == __value_)
-            break;
-    return __first;
-}
-
-// find_if
-
-template <class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_InputIterator
-find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-        if (__pred(*__first))
-            break;
-    return __first;
-}
-
-// find_if_not
-
-template<class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_InputIterator
-find_if_not(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-        if (!__pred(*__first))
-            break;
-    return __first;
-}
-
-// find_end
-
-template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
-__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-           _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred,
-           forward_iterator_tag, forward_iterator_tag)
-{
-    // modeled after search algorithm
-    _ForwardIterator1 __r = __last1;  // __last1 is the "default" answer
-    if (__first2 == __last2)
-        return __r;
-    while (true)
-    {
-        while (true)
-        {
-            if (__first1 == __last1)         // if source exhausted return last correct answer
-                return __r;                  //    (or __last1 if never found)
-            if (__pred(*__first1, *__first2))
-                break;
-            ++__first1;
-        }
-        // *__first1 matches *__first2, now match elements after here
-        _ForwardIterator1 __m1 = __first1;
-        _ForwardIterator2 __m2 = __first2;
-        while (true)
-        {
-            if (++__m2 == __last2)
-            {                         // Pattern exhaused, record answer and search for another one
-                __r = __first1;
-                ++__first1;
-                break;
-            }
-            if (++__m1 == __last1)     // Source exhausted, return last answer
-                return __r;
-            if (!__pred(*__m1, *__m2))  // mismatch, restart with a new __first
-            {
-                ++__first1;
-                break;
-            }  // else there is a match, check next elements
-        }
-    }
-}
-
-template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1
-__find_end(_BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1,
-           _BidirectionalIterator2 __first2, _BidirectionalIterator2 __last2, _BinaryPredicate __pred,
-           bidirectional_iterator_tag, bidirectional_iterator_tag)
-{
-    // modeled after search algorithm (in reverse)
-    if (__first2 == __last2)
-        return __last1;  // Everything matches an empty sequence
-    _BidirectionalIterator1 __l1 = __last1;
-    _BidirectionalIterator2 __l2 = __last2;
-    --__l2;
-    while (true)
-    {
-        // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
-        while (true)
-        {
-            if (__first1 == __l1)  // return __last1 if no element matches *__first2
-                return __last1;
-            if (__pred(*--__l1, *__l2))
-                break;
-        }
-        // *__l1 matches *__l2, now match elements before here
-        _BidirectionalIterator1 __m1 = __l1;
-        _BidirectionalIterator2 __m2 = __l2;
-        while (true)
-        {
-            if (__m2 == __first2)  // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
-                return __m1;
-            if (__m1 == __first1)  // Otherwise if source exhaused, pattern not found
-                return __last1;
-            if (!__pred(*--__m1, *--__m2))  // if there is a mismatch, restart with a new __l1
-            {
-                break;
-            }  // else there is a match, check next elements
-        }
-    }
-}
-
-template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1
-__find_end(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
-           _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
-           random_access_iterator_tag, random_access_iterator_tag)
-{
-    // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
-    typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2;
-    if (__len2 == 0)
-        return __last1;
-    typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1;
-    if (__len1 < __len2)
-        return __last1;
-    const _RandomAccessIterator1 __s = __first1 + (__len2 - 1);  // End of pattern match can't go before here
-    _RandomAccessIterator1 __l1 = __last1;
-    _RandomAccessIterator2 __l2 = __last2;
-    --__l2;
-    while (true)
-    {
-        while (true)
-        {
-            if (__s == __l1)
-                return __last1;
-            if (__pred(*--__l1, *__l2))
-                break;
-        }
-        _RandomAccessIterator1 __m1 = __l1;
-        _RandomAccessIterator2 __m2 = __l2;
-        while (true)
-        {
-            if (__m2 == __first2)
-                return __m1;
-                                 // no need to check range on __m1 because __s guarantees we have enough source
-            if (!__pred(*--__m1, *--__m2))
-            {
-                break;
-            }
-        }
-    }
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator1
-find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
-{
-    return _VSTD::__find_end<typename add_lvalue_reference<_BinaryPredicate>::type>
-                         (__first1, __last1, __first2, __last2, __pred,
-                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
-                          typename iterator_traits<_ForwardIterator2>::iterator_category());
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator1
-find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2, _ForwardIterator2 __last2)
-{
-    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
-    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
-    return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
-}
-
-// find_first_of
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator1
-__find_first_of_ce(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
-{
-    for (; __first1 != __last1; ++__first1)
-        for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
-            if (__pred(*__first1, *__j))
-                return __first1;
-    return __last1;
-}
-
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator1
-find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
-{
-    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __pred);
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator1
-find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-              _ForwardIterator2 __first2, _ForwardIterator2 __last2)
-{
-    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
-    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
-    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
-}
-
-// adjacent_find
-
-template <class _ForwardIterator, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
-{
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-        {
-            if (__pred(*__first, *__i))
-                return __first;
-            __first = __i;
-        }
-    }
-    return __last;
-}
-
-template <class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
-    return _VSTD::adjacent_find(__first, __last, __equal_to<__v>());
-}
-
-// count
-
-template <class _InputIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-typename iterator_traits<_InputIterator>::difference_type
-count(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
-{
-    typename iterator_traits<_InputIterator>::difference_type __r(0);
-    for (; __first != __last; ++__first)
-        if (*__first == __value_)
-            ++__r;
-    return __r;
-}
-
-// count_if
-
-template <class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-typename iterator_traits<_InputIterator>::difference_type
-count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    typename iterator_traits<_InputIterator>::difference_type __r(0);
-    for (; __first != __last; ++__first)
-        if (__pred(*__first))
-            ++__r;
-    return __r;
-}
-
-// mismatch
-
-template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-pair<_InputIterator1, _InputIterator2>
-mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
-         _InputIterator2 __first2, _BinaryPredicate __pred)
-{
-    for (; __first1 != __last1; ++__first1, (void) ++__first2)
-        if (!__pred(*__first1, *__first2))
-            break;
-    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
-}
-
-template <class _InputIterator1, class _InputIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-pair<_InputIterator1, _InputIterator2>
-mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
-{
-    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
-    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
-    return _VSTD::mismatch(__first1, __last1, __first2, __equal_to<__v1, __v2>());
-}
-
-#if _LIBCPP_STD_VER > 11
-template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-pair<_InputIterator1, _InputIterator2>
-mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
-         _InputIterator2 __first2, _InputIterator2 __last2,
-         _BinaryPredicate __pred)
-{
-    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
-        if (!__pred(*__first1, *__first2))
-            break;
-    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
-}
-
-template <class _InputIterator1, class _InputIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-pair<_InputIterator1, _InputIterator2>
-mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
-         _InputIterator2 __first2, _InputIterator2 __last2)
-{
-    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
-    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
-    return _VSTD::mismatch(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
-}
-#endif
-
-// equal
-
-template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred)
-{
-    for (; __first1 != __last1; ++__first1, (void) ++__first2)
-        if (!__pred(*__first1, *__first2))
-            return false;
-    return true;
-}
-
-template <class _InputIterator1, class _InputIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
-{
-    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
-    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
-    return _VSTD::equal(__first1, __last1, __first2, __equal_to<__v1, __v2>());
-}
-
-#if _LIBCPP_STD_VER > 11
-template <class _BinaryPredicate, class _InputIterator1, class _InputIterator2>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-__equal(_InputIterator1 __first1, _InputIterator1 __last1,
-        _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred,
-        input_iterator_tag, input_iterator_tag )
-{
-    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
-        if (!__pred(*__first1, *__first2))
-            return false;
-    return __first1 == __last1 && __first2 == __last2;
-}
-
-template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-__equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
-        _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
-      random_access_iterator_tag, random_access_iterator_tag )
-{
-    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
-        return false;
-    return _VSTD::equal<_RandomAccessIterator1, _RandomAccessIterator2,
-                        typename add_lvalue_reference<_BinaryPredicate>::type>
-                       (__first1, __last1, __first2, __pred );
-}
-
-template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-equal(_InputIterator1 __first1, _InputIterator1 __last1,
-      _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred )
-{
-    return _VSTD::__equal<typename add_lvalue_reference<_BinaryPredicate>::type>
-       (__first1, __last1, __first2, __last2, __pred,
-        typename iterator_traits<_InputIterator1>::iterator_category(),
-        typename iterator_traits<_InputIterator2>::iterator_category());
-}
-
-template <class _InputIterator1, class _InputIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-equal(_InputIterator1 __first1, _InputIterator1 __last1,
-      _InputIterator2 __first2, _InputIterator2 __last2)
-{
-    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
-    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
-    return _VSTD::__equal(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(),
-        typename iterator_traits<_InputIterator1>::iterator_category(),
-        typename iterator_traits<_InputIterator2>::iterator_category());
-}
-#endif
-
-// is_permutation
-
-template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-               _ForwardIterator2 __first2, _BinaryPredicate __pred)
-{
-//  shorten sequences as much as possible by lopping of any equal prefix
-    for (; __first1 != __last1; ++__first1, (void) ++__first2)
-        if (!__pred(*__first1, *__first2))
-            break;
-    if (__first1 == __last1)
-        return true;
-
-//  __first1 != __last1 && *__first1 != *__first2
-    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
-    _D1 __l1 = _VSTD::distance(__first1, __last1);
-    if (__l1 == _D1(1))
-        return false;
-    _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1);
-    // For each element in [f1, l1) see if there are the same number of
-    //    equal elements in [f2, l2)
-    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
-    {
-    //  Have we already counted the number of *__i in [f1, l1)?
-        _ForwardIterator1 __match = __first1;
-        for (; __match != __i; ++__match)
-            if (__pred(*__match, *__i))
-                break;
-        if (__match == __i) {
-            // Count number of *__i in [f2, l2)
-            _D1 __c2 = 0;
-            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
-                if (__pred(*__i, *__j))
-                    ++__c2;
-            if (__c2 == 0)
-                return false;
-            // Count number of *__i in [__i, l1) (we can start with 1)
-            _D1 __c1 = 1;
-            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
-                if (__pred(*__i, *__j))
-                    ++__c1;
-            if (__c1 != __c2)
-                return false;
-        }
-    }
-    return true;
-}
-
-template<class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-               _ForwardIterator2 __first2)
-{
-    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
-    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
-    return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>());
-}
-
-#if _LIBCPP_STD_VER > 11
-template<class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-__is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-                 _ForwardIterator2 __first2, _ForwardIterator2 __last2,
-                 _BinaryPredicate __pred,
-                 forward_iterator_tag, forward_iterator_tag )
-{
-//  shorten sequences as much as possible by lopping of any equal prefix
-    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
-        if (!__pred(*__first1, *__first2))
-            break;
-    if (__first1 == __last1)
-        return __first2 == __last2;
-    else if (__first2 == __last2)
-        return false;
-
-    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
-    _D1 __l1 = _VSTD::distance(__first1, __last1);
-
-    typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2;
-    _D2 __l2 = _VSTD::distance(__first2, __last2);
-    if (__l1 != __l2)
-        return false;
-
-    // For each element in [f1, l1) see if there are the same number of
-    //    equal elements in [f2, l2)
-    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
-    {
-    //  Have we already counted the number of *__i in [f1, l1)?
-        _ForwardIterator1 __match = __first1;
-        for (; __match != __i; ++__match)
-            if (__pred(*__match, *__i))
-                break;
-        if (__match == __i) {
-            // Count number of *__i in [f2, l2)
-            _D1 __c2 = 0;
-            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
-                if (__pred(*__i, *__j))
-                    ++__c2;
-            if (__c2 == 0)
-                return false;
-            // Count number of *__i in [__i, l1) (we can start with 1)
-            _D1 __c1 = 1;
-            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
-                if (__pred(*__i, *__j))
-                    ++__c1;
-            if (__c1 != __c2)
-                return false;
-        }
-    }
-    return true;
-}
-
-template<class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-__is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1,
-               _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2,
-               _BinaryPredicate __pred,
-               random_access_iterator_tag, random_access_iterator_tag )
-{
-    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
-        return false;
-    return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2,
-                                 typename add_lvalue_reference<_BinaryPredicate>::type>
-                                (__first1, __last1, __first2, __pred );
-}
-
-template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-               _ForwardIterator2 __first2, _ForwardIterator2 __last2,
-               _BinaryPredicate __pred )
-{
-    return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>
-       (__first1, __last1, __first2, __last2, __pred,
-        typename iterator_traits<_ForwardIterator1>::iterator_category(),
-        typename iterator_traits<_ForwardIterator2>::iterator_category());
-}
-
-template<class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-               _ForwardIterator2 __first2, _ForwardIterator2 __last2)
-{
-    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
-    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
-    return _VSTD::__is_permutation(__first1, __last1, __first2, __last2,
-        __equal_to<__v1, __v2>(),
-        typename iterator_traits<_ForwardIterator1>::iterator_category(),
-        typename iterator_traits<_ForwardIterator2>::iterator_category());
-}
-#endif
-
-// search
-// __search is in <functional>
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator1
-search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-       _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
-{
-    return _VSTD::__search<typename add_lvalue_reference<_BinaryPredicate>::type>
-                         (__first1, __last1, __first2, __last2, __pred,
-                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
-                          typename iterator_traits<_ForwardIterator2>::iterator_category())
-            .first;
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator1
-search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-       _ForwardIterator2 __first2, _ForwardIterator2 __last2)
-{
-    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
-    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
-    return _VSTD::search(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
-}
-
-
-#if _LIBCPP_STD_VER > 14
-template <class _ForwardIterator, class _Searcher>
-_LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
-{ return __s(__f, __l).first; }
-#endif
-
-// search_n
-
-template <class _BinaryPredicate, class _ForwardIterator, class _Size, class _Tp>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-__search_n(_ForwardIterator __first, _ForwardIterator __last,
-           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, forward_iterator_tag)
-{
-    if (__count <= 0)
-        return __first;
-    while (true)
-    {
-        // Find first element in sequence that matchs __value_, with a mininum of loop checks
-        while (true)
-        {
-            if (__first == __last)  // return __last if no element matches __value_
-                return __last;
-            if (__pred(*__first, __value_))
-                break;
-            ++__first;
-        }
-        // *__first matches __value_, now match elements after here
-        _ForwardIterator __m = __first;
-        _Size __c(0);
-        while (true)
-        {
-            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
-                return __first;
-            if (++__m == __last)  // Otherwise if source exhaused, pattern not found
-                return __last;
-            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
-            {
-                __first = __m;
-                ++__first;
-                break;
-            }  // else there is a match, check next elements
-        }
-    }
-}
-
-template <class _BinaryPredicate, class _RandomAccessIterator, class _Size, class _Tp>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
-__search_n(_RandomAccessIterator __first, _RandomAccessIterator __last,
-           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, random_access_iterator_tag)
-{
-    if (__count <= 0)
-        return __first;
-    _Size __len = static_cast<_Size>(__last - __first);
-    if (__len < __count)
-        return __last;
-    const _RandomAccessIterator __s = __last - (__count - 1);  // Start of pattern match can't go beyond here
-    while (true)
-    {
-        // Find first element in sequence that matchs __value_, with a mininum of loop checks
-        while (true)
-        {
-            if (__first >= __s)  // return __last if no element matches __value_
-                return __last;
-            if (__pred(*__first, __value_))
-                break;
-            ++__first;
-        }
-        // *__first matches __value_, now match elements after here
-        _RandomAccessIterator __m = __first;
-        _Size __c(0);
-        while (true)
-        {
-            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
-                return __first;
-             ++__m;          // no need to check range on __m because __s guarantees we have enough source
-            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
-            {
-                __first = __m;
-                ++__first;
-                break;
-            }  // else there is a match, check next elements
-        }
-    }
-}
-
-template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-search_n(_ForwardIterator __first, _ForwardIterator __last,
-         _Size __count, const _Tp& __value_, _BinaryPredicate __pred)
-{
-    return _VSTD::__search_n<typename add_lvalue_reference<_BinaryPredicate>::type>
-           (__first, __last, _VSTD::__convert_to_integral(__count), __value_, __pred,
-           typename iterator_traits<_ForwardIterator>::iterator_category());
-}
-
-template <class _ForwardIterator, class _Size, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
-    return _VSTD::search_n(__first, __last, _VSTD::__convert_to_integral(__count),
-                           __value_, __equal_to<__v, _Tp>());
-}
-
-// __unwrap_iter, __rewrap_iter
-
-// The job of __unwrap_iter is to lower contiguous iterators (such as
-// vector<T>::iterator) into pointers, to reduce the number of template
-// instantiations and to enable pointer-based optimizations e.g. in std::copy.
-// For iterators that are not contiguous, it must be a no-op.
-// In debug mode, we don't do this.
-//
-// __unwrap_iter is non-constexpr for user-defined iterators whose
-// `to_address` and/or `operator->` is non-constexpr. This is okay; but we
-// try to avoid doing __unwrap_iter in constant-evaluated contexts anyway.
-//
-// Some algorithms (e.g. std::copy, but not std::sort) need to convert an
-// "unwrapped" result back into a contiguous iterator. Since contiguous iterators
-// are random-access, we can do this portably using iterator arithmetic; this
-// is the job of __rewrap_iter.
-
-template <class _Iter, bool = __is_cpp17_contiguous_iterator<_Iter>::value>
-struct __unwrap_iter_impl {
-    static _LIBCPP_CONSTEXPR _Iter
-    __apply(_Iter __i) _NOEXCEPT {
-        return __i;
-    }
-};
-
-#if _LIBCPP_DEBUG_LEVEL < 2
-
-template <class _Iter>
-struct __unwrap_iter_impl<_Iter, true> {
-    static _LIBCPP_CONSTEXPR decltype(_VSTD::__to_address(declval<_Iter>()))
-    __apply(_Iter __i) _NOEXCEPT {
-        return _VSTD::__to_address(__i);
-    }
-};
-
-#endif // _LIBCPP_DEBUG_LEVEL < 2
-
-template<class _Iter, class _Impl = __unwrap_iter_impl<_Iter> >
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-decltype(_Impl::__apply(declval<_Iter>()))
-__unwrap_iter(_Iter __i) _NOEXCEPT
-{
-    return _Impl::__apply(__i);
-}
-
-template<class _OrigIter>
-_OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
-{
-    return __result;
-}
-
-template<class _OrigIter, class _UnwrappedIter>
-_OrigIter __rewrap_iter(_OrigIter __first, _UnwrappedIter __result)
-{
-    // Precondition: __result is reachable from __first
-    // Precondition: _OrigIter is a contiguous iterator
-    return __first + (__result - _VSTD::__unwrap_iter(__first));
-}
-
-// copy
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-__copy_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    for (; __first != __last; ++__first, (void) ++__result)
-        *__result = *__first;
-    return __result;
-}
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-_OutputIterator
-__copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    return _VSTD::__copy_constexpr(__first, __last, __result);
-}
-
-template <class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
-<
-    is_same<typename remove_const<_Tp>::type, _Up>::value &&
-    is_trivially_copy_assignable<_Up>::value,
-    _Up*
->::type
-__copy(_Tp* __first, _Tp* __last, _Up* __result)
-{
-    const size_t __n = static_cast<size_t>(__last - __first);
-    if (__n > 0)
-        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
-    return __result + __n;
-}
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    if (__libcpp_is_constant_evaluated()) {
-        return _VSTD::__copy_constexpr(__first, __last, __result);
-    } else {
-        return _VSTD::__rewrap_iter(__result,
-            _VSTD::__copy(_VSTD::__unwrap_iter(__first),
-                          _VSTD::__unwrap_iter(__last),
-                          _VSTD::__unwrap_iter(__result)));
-    }
-}
-
-// copy_backward
-
-template <class _BidirectionalIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-__copy_backward_constexpr(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
-{
-    while (__first != __last)
-        *--__result = *--__last;
-    return __result;
-}
-
-template <class _BidirectionalIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-_OutputIterator
-__copy_backward(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
-{
-    return _VSTD::__copy_backward_constexpr(__first, __last, __result);
-}
-
-template <class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
-<
-    is_same<typename remove_const<_Tp>::type, _Up>::value &&
-    is_trivially_copy_assignable<_Up>::value,
-    _Up*
->::type
-__copy_backward(_Tp* __first, _Tp* __last, _Up* __result)
-{
-    const size_t __n = static_cast<size_t>(__last - __first);
-    if (__n > 0)
-    {
-        __result -= __n;
-        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
-    }
-    return __result;
-}
-
-template <class _BidirectionalIterator1, class _BidirectionalIterator2>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_BidirectionalIterator2
-copy_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
-              _BidirectionalIterator2 __result)
-{
-    if (__libcpp_is_constant_evaluated()) {
-        return _VSTD::__copy_backward_constexpr(__first, __last, __result);
-    } else {
-        return _VSTD::__rewrap_iter(__result,
-            _VSTD::__copy_backward(_VSTD::__unwrap_iter(__first),
-                                   _VSTD::__unwrap_iter(__last),
-                                   _VSTD::__unwrap_iter(__result)));
-    }
-}
-
-// copy_if
-
-template<class _InputIterator, class _OutputIterator, class _Predicate>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-copy_if(_InputIterator __first, _InputIterator __last,
-        _OutputIterator __result, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-    {
-        if (__pred(*__first))
-        {
-            *__result = *__first;
-            ++__result;
-        }
-    }
-    return __result;
-}
-
-// copy_n
-
-template<class _InputIterator, class _Size, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-typename enable_if
-<
-    __is_cpp17_input_iterator<_InputIterator>::value &&
-   !__is_cpp17_random_access_iterator<_InputIterator>::value,
-    _OutputIterator
->::type
-copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
-{
-    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
-    _IntegralSize __n = __orig_n;
-    if (__n > 0)
-    {
-        *__result = *__first;
-        ++__result;
-        for (--__n; __n > 0; --__n)
-        {
-            ++__first;
-            *__result = *__first;
-            ++__result;
-        }
-    }
-    return __result;
-}
-
-template<class _InputIterator, class _Size, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-typename enable_if
-<
-    __is_cpp17_random_access_iterator<_InputIterator>::value,
-    _OutputIterator
->::type
-copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
-{
-    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
-    _IntegralSize __n = __orig_n;
-    return _VSTD::copy(__first, __first + __n, __result);
-}
-
-// move
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-_OutputIterator
-__move_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    for (; __first != __last; ++__first, (void) ++__result)
-        *__result = _VSTD::move(*__first);
-    return __result;
-}
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-_OutputIterator
-__move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    return _VSTD::__move_constexpr(__first, __last, __result);
-}
-
-template <class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-typename enable_if
-<
-    is_same<typename remove_const<_Tp>::type, _Up>::value &&
-    is_trivially_move_assignable<_Up>::value,
-    _Up*
->::type
-__move(_Tp* __first, _Tp* __last, _Up* __result)
-{
-    const size_t __n = static_cast<size_t>(__last - __first);
-    if (__n > 0)
-        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
-    return __result + __n;
-}
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    if (__libcpp_is_constant_evaluated()) {
-        return _VSTD::__move_constexpr(__first, __last, __result);
-    } else {
-        return _VSTD::__rewrap_iter(__result,
-            _VSTD::__move(_VSTD::__unwrap_iter(__first),
-                          _VSTD::__unwrap_iter(__last),
-                          _VSTD::__unwrap_iter(__result)));
-    }
-}
-
-// move_backward
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-_OutputIterator
-__move_backward_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    while (__first != __last)
-        *--__result = _VSTD::move(*--__last);
-    return __result;
-}
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-_OutputIterator
-__move_backward(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    return _VSTD::__move_backward_constexpr(__first, __last, __result);
-}
-
-template <class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-typename enable_if
-<
-    is_same<typename remove_const<_Tp>::type, _Up>::value &&
-    is_trivially_move_assignable<_Up>::value,
-    _Up*
->::type
-__move_backward(_Tp* __first, _Tp* __last, _Up* __result)
-{
-    const size_t __n = static_cast<size_t>(__last - __first);
-    if (__n > 0)
-    {
-        __result -= __n;
-        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
-    }
-    return __result;
-}
-
-template <class _BidirectionalIterator1, class _BidirectionalIterator2>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_BidirectionalIterator2
-move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
-              _BidirectionalIterator2 __result)
-{
-    if (__libcpp_is_constant_evaluated()) {
-        return _VSTD::__move_backward_constexpr(__first, __last, __result);
-    } else {
-        return _VSTD::__rewrap_iter(__result,
-            _VSTD::__move_backward(_VSTD::__unwrap_iter(__first),
-                                   _VSTD::__unwrap_iter(__last),
-                                   _VSTD::__unwrap_iter(__result)));
-    }
-}
-
-// iter_swap
-
-// moved to <type_traits> for better swap / noexcept support
-
-// transform
-
-template <class _InputIterator, class _OutputIterator, class _UnaryOperation>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-transform(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _UnaryOperation __op)
-{
-    for (; __first != __last; ++__first, (void) ++__result)
-        *__result = __op(*__first);
-    return __result;
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _BinaryOperation>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-transform(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2,
-          _OutputIterator __result, _BinaryOperation __binary_op)
-{
-    for (; __first1 != __last1; ++__first1, (void) ++__first2, ++__result)
-        *__result = __binary_op(*__first1, *__first2);
-    return __result;
-}
-
-// replace
-
-template <class _ForwardIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-replace(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __old_value, const _Tp& __new_value)
-{
-    for (; __first != __last; ++__first)
-        if (*__first == __old_value)
-            *__first = __new_value;
-}
-
-// replace_if
-
-template <class _ForwardIterator, class _Predicate, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-replace_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, const _Tp& __new_value)
-{
-    for (; __first != __last; ++__first)
-        if (__pred(*__first))
-            *__first = __new_value;
-}
-
-// replace_copy
-
-template <class _InputIterator, class _OutputIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-replace_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
-             const _Tp& __old_value, const _Tp& __new_value)
-{
-    for (; __first != __last; ++__first, (void) ++__result)
-        if (*__first == __old_value)
-            *__result = __new_value;
-        else
-            *__result = *__first;
-    return __result;
-}
-
-// replace_copy_if
-
-template <class _InputIterator, class _OutputIterator, class _Predicate, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-replace_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
-                _Predicate __pred, const _Tp& __new_value)
-{
-    for (; __first != __last; ++__first, (void) ++__result)
-        if (__pred(*__first))
-            *__result = __new_value;
-        else
-            *__result = *__first;
-    return __result;
-}
-
-// fill_n
-
-template <class _OutputIterator, class _Size, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-__fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
-{
-    for (; __n > 0; ++__first, (void) --__n)
-        *__first = __value_;
-    return __first;
-}
-
-template <class _OutputIterator, class _Size, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
-{
-   return _VSTD::__fill_n(__first, _VSTD::__convert_to_integral(__n), __value_);
-}
-
-// fill
-
-template <class _ForwardIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, forward_iterator_tag)
-{
-    for (; __first != __last; ++__first)
-        *__first = __value_;
-}
-
-template <class _RandomAccessIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value_, random_access_iterator_tag)
-{
-    _VSTD::fill_n(__first, __last - __first, __value_);
-}
-
-template <class _ForwardIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
-{
-    _VSTD::__fill(__first, __last, __value_, typename iterator_traits<_ForwardIterator>::iterator_category());
-}
-
-// generate
-
-template <class _ForwardIterator, class _Generator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-generate(_ForwardIterator __first, _ForwardIterator __last, _Generator __gen)
-{
-    for (; __first != __last; ++__first)
-        *__first = __gen();
-}
-
-// generate_n
-
-template <class _OutputIterator, class _Size, class _Generator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-generate_n(_OutputIterator __first, _Size __orig_n, _Generator __gen)
-{
-    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
-    _IntegralSize __n = __orig_n;
-    for (; __n > 0; ++__first, (void) --__n)
-        *__first = __gen();
-    return __first;
-}
-
-// remove
-
-template <class _ForwardIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-remove(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
-{
-    __first = _VSTD::find(__first, __last, __value_);
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-        {
-            if (!(*__i == __value_))
-            {
-                *__first = _VSTD::move(*__i);
-                ++__first;
-            }
-        }
-    }
-    return __first;
-}
-
-// remove_if
-
-template <class _ForwardIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-remove_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
-{
-    __first = _VSTD::find_if<_ForwardIterator, typename add_lvalue_reference<_Predicate>::type>
-                           (__first, __last, __pred);
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-        {
-            if (!__pred(*__i))
-            {
-                *__first = _VSTD::move(*__i);
-                ++__first;
-            }
-        }
-    }
-    return __first;
-}
-
-// remove_copy
-
-template <class _InputIterator, class _OutputIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-remove_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, const _Tp& __value_)
-{
-    for (; __first != __last; ++__first)
-    {
-        if (!(*__first == __value_))
-        {
-            *__result = *__first;
-            ++__result;
-        }
-    }
-    return __result;
-}
-
-// remove_copy_if
-
-template <class _InputIterator, class _OutputIterator, class _Predicate>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-remove_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-    {
-        if (!__pred(*__first))
-        {
-            *__result = *__first;
-            ++__result;
-        }
-    }
-    return __result;
-}
-
-// unique
-
-template <class _ForwardIterator, class _BinaryPredicate>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
-{
-    __first = _VSTD::adjacent_find<_ForwardIterator, typename add_lvalue_reference<_BinaryPredicate>::type>
-                                 (__first, __last, __pred);
-    if (__first != __last)
-    {
-        // ...  a  a  ?  ...
-        //      f     i
-        _ForwardIterator __i = __first;
-        for (++__i; ++__i != __last;)
-            if (!__pred(*__first, *__i))
-                *++__first = _VSTD::move(*__i);
-        ++__first;
-    }
-    return __first;
-}
-
-template <class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-unique(_ForwardIterator __first, _ForwardIterator __last)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
-    return _VSTD::unique(__first, __last, __equal_to<__v>());
-}
-
-// unique_copy
-
-template <class _BinaryPredicate, class _InputIterator, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
-__unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
-              input_iterator_tag, output_iterator_tag)
-{
-    if (__first != __last)
-    {
-        typename iterator_traits<_InputIterator>::value_type __t(*__first);
-        *__result = __t;
-        ++__result;
-        while (++__first != __last)
-        {
-            if (!__pred(__t, *__first))
-            {
-                __t = *__first;
-                *__result = __t;
-                ++__result;
-            }
-        }
-    }
-    return __result;
-}
-
-template <class _BinaryPredicate, class _ForwardIterator, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
-__unique_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
-              forward_iterator_tag, output_iterator_tag)
-{
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        *__result = *__i;
-        ++__result;
-        while (++__first != __last)
-        {
-            if (!__pred(*__i, *__first))
-            {
-                *__result = *__first;
-                ++__result;
-                __i = __first;
-            }
-        }
-    }
-    return __result;
-}
-
-template <class _BinaryPredicate, class _InputIterator, class _ForwardIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-__unique_copy(_InputIterator __first, _InputIterator __last, _ForwardIterator __result, _BinaryPredicate __pred,
-              input_iterator_tag, forward_iterator_tag)
-{
-    if (__first != __last)
-    {
-        *__result = *__first;
-        while (++__first != __last)
-            if (!__pred(*__result, *__first))
-                *++__result = *__first;
-        ++__result;
-    }
-    return __result;
-}
-
-template <class _InputIterator, class _OutputIterator, class _BinaryPredicate>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred)
-{
-    return _VSTD::__unique_copy<typename add_lvalue_reference<_BinaryPredicate>::type>
-                              (__first, __last, __result, __pred,
-                               typename iterator_traits<_InputIterator>::iterator_category(),
-                               typename iterator_traits<_OutputIterator>::iterator_category());
-}
-
-template <class _InputIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
-{
-    typedef typename iterator_traits<_InputIterator>::value_type __v;
-    return _VSTD::unique_copy(__first, __last, __result, __equal_to<__v>());
-}
-
-// reverse
-
-template <class _BidirectionalIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
-{
-    while (__first != __last)
-    {
-        if (__first == --__last)
-            break;
-        _VSTD::iter_swap(__first, __last);
-        ++__first;
-    }
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
-{
-    if (__first != __last)
-        for (; __first < --__last; ++__first)
-            _VSTD::iter_swap(__first, __last);
-}
-
-template <class _BidirectionalIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
-{
-    _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
-}
-
-// reverse_copy
-
-template <class _BidirectionalIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
-{
-    for (; __first != __last; ++__result)
-        *__result = *--__last;
-    return __result;
-}
-
-// rotate
-
-template <class _ForwardIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator
-__rotate_left(_ForwardIterator __first, _ForwardIterator __last)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-    value_type __tmp = _VSTD::move(*__first);
-    _ForwardIterator __lm1 = _VSTD::move(_VSTD::next(__first), __last, __first);
-    *__lm1 = _VSTD::move(__tmp);
-    return __lm1;
-}
-
-template <class _BidirectionalIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _BidirectionalIterator
-__rotate_right(_BidirectionalIterator __first, _BidirectionalIterator __last)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    _BidirectionalIterator __lm1 = _VSTD::prev(__last);
-    value_type __tmp = _VSTD::move(*__lm1);
-    _BidirectionalIterator __fp1 = _VSTD::move_backward(__first, __lm1, __last);
-    *__first = _VSTD::move(__tmp);
-    return __fp1;
-}
-
-template <class _ForwardIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX14 _ForwardIterator
-__rotate_forward(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
-{
-    _ForwardIterator __i = __middle;
-    while (true)
-    {
-        swap(*__first, *__i);
-        ++__first;
-        if (++__i == __last)
-            break;
-        if (__first == __middle)
-            __middle = __i;
-    }
-    _ForwardIterator __r = __first;
-    if (__first != __middle)
-    {
-        __i = __middle;
-        while (true)
-        {
-            swap(*__first, *__i);
-            ++__first;
-            if (++__i == __last)
-            {
-                if (__first == __middle)
-                    break;
-                __i = __middle;
-            }
-            else if (__first == __middle)
-                __middle = __i;
-        }
-    }
-    return __r;
-}
-
-template<typename _Integral>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_CONSTEXPR_AFTER_CXX14 _Integral
-__algo_gcd(_Integral __x, _Integral __y)
-{
-    do
-    {
-        _Integral __t = __x % __y;
-        __x = __y;
-        __y = __t;
-    } while (__y);
-    return __x;
-}
-
-template<typename _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX14 _RandomAccessIterator
-__rotate_gcd(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-
-    const difference_type __m1 = __middle - __first;
-    const difference_type __m2 = __last - __middle;
-    if (__m1 == __m2)
-    {
-        _VSTD::swap_ranges(__first, __middle, __middle);
-        return __middle;
-    }
-    const difference_type __g = _VSTD::__algo_gcd(__m1, __m2);
-    for (_RandomAccessIterator __p = __first + __g; __p != __first;)
-    {
-        value_type __t(_VSTD::move(*--__p));
-        _RandomAccessIterator __p1 = __p;
-        _RandomAccessIterator __p2 = __p1 + __m1;
-        do
-        {
-            *__p1 = _VSTD::move(*__p2);
-            __p1 = __p2;
-            const difference_type __d = __last - __p2;
-            if (__m1 < __d)
-                __p2 += __m1;
-            else
-                __p2 = __first + (__m1 - __d);
-        } while (__p2 != __p);
-        *__p1 = _VSTD::move(__t);
-    }
-    return __first + __m2;
-}
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator
-__rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
-         _VSTD::forward_iterator_tag)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-    if (is_trivially_move_assignable<value_type>::value)
-    {
-        if (_VSTD::next(__first) == __middle)
-            return _VSTD::__rotate_left(__first, __last);
-    }
-    return _VSTD::__rotate_forward(__first, __middle, __last);
-}
-
-template <class _BidirectionalIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _BidirectionalIterator
-__rotate(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
-         bidirectional_iterator_tag)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    if (is_trivially_move_assignable<value_type>::value)
-    {
-        if (_VSTD::next(__first) == __middle)
-            return _VSTD::__rotate_left(__first, __last);
-        if (_VSTD::next(__middle) == __last)
-            return _VSTD::__rotate_right(__first, __last);
-    }
-    return _VSTD::__rotate_forward(__first, __middle, __last);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator
-__rotate(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
-         random_access_iterator_tag)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    if (is_trivially_move_assignable<value_type>::value)
-    {
-        if (_VSTD::next(__first) == __middle)
-            return _VSTD::__rotate_left(__first, __last);
-        if (_VSTD::next(__middle) == __last)
-            return _VSTD::__rotate_right(__first, __last);
-        return _VSTD::__rotate_gcd(__first, __middle, __last);
-    }
-    return _VSTD::__rotate_forward(__first, __middle, __last);
-}
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
-{
-    if (__first == __middle)
-        return __last;
-    if (__middle == __last)
-        return __first;
-    return _VSTD::__rotate(__first, __middle, __last,
-                           typename iterator_traits<_ForwardIterator>::iterator_category());
-}
-
-// rotate_copy
-
-template <class _ForwardIterator, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-rotate_copy(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last, _OutputIterator __result)
-{
-    return _VSTD::copy(__first, __middle, _VSTD::copy(__middle, __last, __result));
-}
-
-// min_element
-
-template <class _ForwardIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_ForwardIterator
-min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
-{
-    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
-        "std::min_element requires a ForwardIterator");
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-            if (__comp(*__i, *__first))
-                __first = __i;
-    }
-    return __first;
-}
-
-template <class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_ForwardIterator
-min_element(_ForwardIterator __first, _ForwardIterator __last)
-{
-    return _VSTD::min_element(__first, __last,
-              __less<typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// min
-
-template <class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const _Tp&
-min(const _Tp& __a, const _Tp& __b, _Compare __comp)
-{
-    return __comp(__b, __a) ? __b : __a;
-}
-
-template <class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const _Tp&
-min(const _Tp& __a, const _Tp& __b)
-{
-    return _VSTD::min(__a, __b, __less<_Tp>());
-}
-
-#ifndef _LIBCPP_CXX03_LANG
-
-template<class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp
-min(initializer_list<_Tp> __t, _Compare __comp)
-{
-    return *_VSTD::min_element(__t.begin(), __t.end(), __comp);
-}
-
-template<class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp
-min(initializer_list<_Tp> __t)
-{
-    return *_VSTD::min_element(__t.begin(), __t.end(), __less<_Tp>());
-}
-
-#endif // _LIBCPP_CXX03_LANG
-
-// max_element
-
-template <class _ForwardIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_ForwardIterator
-max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
-{
-    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
-        "std::max_element requires a ForwardIterator");
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-            if (__comp(*__first, *__i))
-                __first = __i;
-    }
-    return __first;
-}
-
-
-template <class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_ForwardIterator
-max_element(_ForwardIterator __first, _ForwardIterator __last)
-{
-    return _VSTD::max_element(__first, __last,
-              __less<typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// max
-
-template <class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const _Tp&
-max(const _Tp& __a, const _Tp& __b, _Compare __comp)
-{
-    return __comp(__a, __b) ? __b : __a;
-}
-
-template <class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const _Tp&
-max(const _Tp& __a, const _Tp& __b)
-{
-    return _VSTD::max(__a, __b, __less<_Tp>());
-}
-
-#ifndef _LIBCPP_CXX03_LANG
-
-template<class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp
-max(initializer_list<_Tp> __t, _Compare __comp)
-{
-    return *_VSTD::max_element(__t.begin(), __t.end(), __comp);
-}
-
-template<class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp
-max(initializer_list<_Tp> __t)
-{
-    return *_VSTD::max_element(__t.begin(), __t.end(), __less<_Tp>());
-}
-
-#endif // _LIBCPP_CXX03_LANG
-
-#if _LIBCPP_STD_VER > 14
-// clamp
-template<class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-const _Tp&
-clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi, _Compare __comp)
-{
-    _LIBCPP_ASSERT(!__comp(__hi, __lo), "Bad bounds passed to std::clamp");
-    return __comp(__v, __lo) ? __lo : __comp(__hi, __v) ? __hi : __v;
-
-}
-
-template<class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-const _Tp&
-clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi)
-{
-    return _VSTD::clamp(__v, __lo, __hi, __less<_Tp>());
-}
-#endif
-
-// minmax_element
-
-template <class _ForwardIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<_ForwardIterator, _ForwardIterator>
-minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
-{
-  static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
-        "std::minmax_element requires a ForwardIterator");
-  pair<_ForwardIterator, _ForwardIterator> __result(__first, __first);
-  if (__first != __last)
-  {
-      if (++__first != __last)
-      {
-          if (__comp(*__first, *__result.first))
-              __result.first = __first;
-          else
-              __result.second = __first;
-          while (++__first != __last)
-          {
-              _ForwardIterator __i = __first;
-              if (++__first == __last)
-              {
-                  if (__comp(*__i, *__result.first))
-                      __result.first = __i;
-                  else if (!__comp(*__i, *__result.second))
-                      __result.second = __i;
-                  break;
-              }
-              else
-              {
-                  if (__comp(*__first, *__i))
-                  {
-                      if (__comp(*__first, *__result.first))
-                          __result.first = __first;
-                      if (!__comp(*__i, *__result.second))
-                          __result.second = __i;
-                  }
-                  else
-                  {
-                      if (__comp(*__i, *__result.first))
-                          __result.first = __i;
-                      if (!__comp(*__first, *__result.second))
-                          __result.second = __first;
-                  }
-              }
-          }
-      }
-  }
-  return __result;
-}
-
-template <class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<_ForwardIterator, _ForwardIterator>
-minmax_element(_ForwardIterator __first, _ForwardIterator __last)
-{
-    return _VSTD::minmax_element(__first, __last,
-              __less<typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// minmax
-
-template<class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<const _Tp&, const _Tp&>
-minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
-{
-    return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a) :
-                              pair<const _Tp&, const _Tp&>(__a, __b);
-}
-
-template<class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<const _Tp&, const _Tp&>
-minmax(const _Tp& __a, const _Tp& __b)
-{
-    return _VSTD::minmax(__a, __b, __less<_Tp>());
-}
-
-#ifndef _LIBCPP_CXX03_LANG
-
-template<class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<_Tp, _Tp>
-minmax(initializer_list<_Tp> __t, _Compare __comp)
-{
-    typedef typename initializer_list<_Tp>::const_iterator _Iter;
-    _Iter __first = __t.begin();
-    _Iter __last  = __t.end();
-    pair<_Tp, _Tp> __result(*__first, *__first);
-
-    ++__first;
-    if (__t.size() % 2 == 0)
-    {
-        if (__comp(*__first,  __result.first))
-            __result.first  = *__first;
-        else
-            __result.second = *__first;
-        ++__first;
-    }
-
-    while (__first != __last)
-    {
-        _Tp __prev = *__first++;
-        if (__comp(*__first, __prev)) {
-            if ( __comp(*__first, __result.first)) __result.first  = *__first;
-            if (!__comp(__prev, __result.second))  __result.second = __prev;
-            }
-        else {
-            if ( __comp(__prev, __result.first))    __result.first  = __prev;
-            if (!__comp(*__first, __result.second)) __result.second = *__first;
-            }
-
-        __first++;
-    }
-    return __result;
-}
-
-template<class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<_Tp, _Tp>
-minmax(initializer_list<_Tp> __t)
-{
-    return _VSTD::minmax(__t, __less<_Tp>());
-}
-
-#endif // _LIBCPP_CXX03_LANG
-
-// random_shuffle
-
-// __independent_bits_engine
-
-template <unsigned long long _Xp, size_t _Rp>
-struct __log2_imp
-{
-    static const size_t value = _Xp & ((unsigned long long)(1) << _Rp) ? _Rp
-                                           : __log2_imp<_Xp, _Rp - 1>::value;
-};
-
-template <unsigned long long _Xp>
-struct __log2_imp<_Xp, 0>
-{
-    static const size_t value = 0;
-};
-
-template <size_t _Rp>
-struct __log2_imp<0, _Rp>
-{
-    static const size_t value = _Rp + 1;
-};
-
-template <class _UIntType, _UIntType _Xp>
-struct __log2
-{
-    static const size_t value = __log2_imp<_Xp,
-                                         sizeof(_UIntType) * __CHAR_BIT__ - 1>::value;
-};
-
-template<class _Engine, class _UIntType>
-class __independent_bits_engine
-{
-public:
-    // types
-    typedef _UIntType result_type;
-
-private:
-    typedef typename _Engine::result_type _Engine_result_type;
-    typedef typename conditional
-        <
-            sizeof(_Engine_result_type) <= sizeof(result_type),
-                result_type,
-                _Engine_result_type
-        >::type _Working_result_type;
-
-    _Engine& __e_;
-    size_t __w_;
-    size_t __w0_;
-    size_t __n_;
-    size_t __n0_;
-    _Working_result_type __y0_;
-    _Working_result_type __y1_;
-    _Engine_result_type __mask0_;
-    _Engine_result_type __mask1_;
-
-#ifdef _LIBCPP_CXX03_LANG
-    static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
-                                          + _Working_result_type(1);
-#else
-    static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
-                                                      + _Working_result_type(1);
-#endif
-    static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
-    static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
-    static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
-
-public:
-    // constructors and seeding functions
-    __independent_bits_engine(_Engine& __e, size_t __w);
-
-    // generating functions
-    result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
-
-private:
-    result_type __eval(false_type);
-    result_type __eval(true_type);
-};
-
-template<class _Engine, class _UIntType>
-__independent_bits_engine<_Engine, _UIntType>
-    ::__independent_bits_engine(_Engine& __e, size_t __w)
-        : __e_(__e),
-          __w_(__w)
-{
-    __n_ = __w_ / __m + (__w_ % __m != 0);
-    __w0_ = __w_ / __n_;
-    if (_Rp == 0)
-        __y0_ = _Rp;
-    else if (__w0_ < _WDt)
-        __y0_ = (_Rp >> __w0_) << __w0_;
-    else
-        __y0_ = 0;
-    if (_Rp - __y0_ > __y0_ / __n_)
-    {
-        ++__n_;
-        __w0_ = __w_ / __n_;
-        if (__w0_ < _WDt)
-            __y0_ = (_Rp >> __w0_) << __w0_;
-        else
-            __y0_ = 0;
-    }
-    __n0_ = __n_ - __w_ % __n_;
-    if (__w0_ < _WDt - 1)
-        __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
-    else
-        __y1_ = 0;
-    __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) :
-                          _Engine_result_type(0);
-    __mask1_ = __w0_ < _EDt - 1 ?
-                               _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) :
-                               _Engine_result_type(~0);
-}
-
-template<class _Engine, class _UIntType>
-inline
-_UIntType
-__independent_bits_engine<_Engine, _UIntType>::__eval(false_type)
-{
-    return static_cast<result_type>(__e_() & __mask0_);
-}
-
-template<class _Engine, class _UIntType>
-_UIntType
-__independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
-{
-    const size_t _WRt = numeric_limits<result_type>::digits;
-    result_type _Sp = 0;
-    for (size_t __k = 0; __k < __n0_; ++__k)
-    {
-        _Engine_result_type __u;
-        do
-        {
-            __u = __e_() - _Engine::min();
-        } while (__u >= __y0_);
-        if (__w0_ < _WRt)
-            _Sp <<= __w0_;
-        else
-            _Sp = 0;
-        _Sp += __u & __mask0_;
-    }
-    for (size_t __k = __n0_; __k < __n_; ++__k)
-    {
-        _Engine_result_type __u;
-        do
-        {
-            __u = __e_() - _Engine::min();
-        } while (__u >= __y1_);
-        if (__w0_ < _WRt - 1)
-            _Sp <<= __w0_ + 1;
-        else
-            _Sp = 0;
-        _Sp += __u & __mask1_;
-    }
-    return _Sp;
-}
-
-// uniform_int_distribution
-
-template<class _IntType = int>
-class uniform_int_distribution
-{
-public:
-    // types
-    typedef _IntType result_type;
-
-    class param_type
-    {
-        result_type __a_;
-        result_type __b_;
-    public:
-        typedef uniform_int_distribution distribution_type;
-
-        explicit param_type(result_type __a = 0,
-                            result_type __b = numeric_limits<result_type>::max())
-            : __a_(__a), __b_(__b) {}
-
-        result_type a() const {return __a_;}
-        result_type b() const {return __b_;}
-
-        friend bool operator==(const param_type& __x, const param_type& __y)
-            {return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
-        friend bool operator!=(const param_type& __x, const param_type& __y)
-            {return !(__x == __y);}
-    };
-
-private:
-    param_type __p_;
-
-public:
-    // constructors and reset functions
-#ifndef _LIBCPP_CXX03_LANG
-    uniform_int_distribution() : uniform_int_distribution(0) {}
-    explicit uniform_int_distribution(
-        result_type __a, result_type __b = numeric_limits<result_type>::max())
-        : __p_(param_type(__a, __b)) {}
-#else
-    explicit uniform_int_distribution(
-        result_type __a = 0,
-        result_type __b = numeric_limits<result_type>::max())
-        : __p_(param_type(__a, __b)) {}
-#endif
-    explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
-    void reset() {}
-
-    // generating functions
-    template<class _URNG> result_type operator()(_URNG& __g)
-        {return (*this)(__g, __p_);}
-    template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
-
-    // property functions
-    result_type a() const {return __p_.a();}
-    result_type b() const {return __p_.b();}
-
-    param_type param() const {return __p_;}
-    void param(const param_type& __p) {__p_ = __p;}
-
-    result_type min() const {return a();}
-    result_type max() const {return b();}
-
-    friend bool operator==(const uniform_int_distribution& __x,
-                           const uniform_int_distribution& __y)
-        {return __x.__p_ == __y.__p_;}
-    friend bool operator!=(const uniform_int_distribution& __x,
-                           const uniform_int_distribution& __y)
-            {return !(__x == __y);}
-};
-
-template<class _IntType>
-template<class _URNG>
-typename uniform_int_distribution<_IntType>::result_type
-uniform_int_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
-_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
-{
-    typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t),
-                                            uint32_t, uint64_t>::type _UIntType;
-    const _UIntType _Rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
-    if (_Rp == 1)
-        return __p.a();
-    const size_t _Dt = numeric_limits<_UIntType>::digits;
-    typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
-    if (_Rp == 0)
-        return static_cast<result_type>(_Eng(__g, _Dt)());
-    size_t __w = _Dt - __libcpp_clz(_Rp) - 1;
-    if ((_Rp & (numeric_limits<_UIntType>::max() >> (_Dt - __w))) != 0)
-        ++__w;
-    _Eng __e(__g, __w);
-    _UIntType __u;
-    do
-    {
-        __u = __e();
-    } while (__u >= _Rp);
-    return static_cast<result_type>(__u + __p.a());
-}
-
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE) \
-  || defined(_LIBCPP_BUILDING_LIBRARY)
-class _LIBCPP_TYPE_VIS __rs_default;
-
-_LIBCPP_FUNC_VIS __rs_default __rs_get();
-
-class _LIBCPP_TYPE_VIS __rs_default
-{
-    static unsigned __c_;
-
-    __rs_default();
-public:
-    typedef uint_fast32_t result_type;
-
-    static const result_type _Min = 0;
-    static const result_type _Max = 0xFFFFFFFF;
-
-    __rs_default(const __rs_default&);
-    ~__rs_default();
-
-    result_type operator()();
-
-    static _LIBCPP_CONSTEXPR result_type min() {return _Min;}
-    static _LIBCPP_CONSTEXPR result_type max() {return _Max;}
-
-    friend _LIBCPP_FUNC_VIS __rs_default __rs_get();
-};
-
-_LIBCPP_FUNC_VIS __rs_default __rs_get();
-
-template <class _RandomAccessIterator>
-_LIBCPP_DEPRECATED_IN_CXX14 void
-random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    typedef uniform_int_distribution<ptrdiff_t> _Dp;
-    typedef typename _Dp::param_type _Pp;
-    difference_type __d = __last - __first;
-    if (__d > 1)
-    {
-        _Dp __uid;
-        __rs_default __g = __rs_get();
-        for (--__last, (void) --__d; __first < __last; ++__first, (void) --__d)
-        {
-            difference_type __i = __uid(__g, _Pp(0, __d));
-            if (__i != difference_type(0))
-                swap(*__first, *(__first + __i));
-        }
-    }
-}
-
-template <class _RandomAccessIterator, class _RandomNumberGenerator>
-_LIBCPP_DEPRECATED_IN_CXX14 void
-random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
-#ifndef _LIBCPP_CXX03_LANG
-               _RandomNumberGenerator&& __rand)
-#else
-               _RandomNumberGenerator& __rand)
-#endif
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    difference_type __d = __last - __first;
-    if (__d > 1)
-    {
-        for (--__last; __first < __last; ++__first, (void) --__d)
-        {
-            difference_type __i = __rand(__d);
-            if (__i != difference_type(0))
-              swap(*__first, *(__first + __i));
-        }
-    }
-}
-#endif
-
-template <class _PopulationIterator, class _SampleIterator, class _Distance,
-          class _UniformRandomNumberGenerator>
-_LIBCPP_INLINE_VISIBILITY
-_SampleIterator __sample(_PopulationIterator __first,
-                         _PopulationIterator __last, _SampleIterator __output_iter,
-                         _Distance __n,
-                         _UniformRandomNumberGenerator & __g,
-                         input_iterator_tag) {
-
-  _Distance __k = 0;
-  for (; __first != __last && __k < __n; ++__first, (void) ++__k)
-    __output_iter[__k] = *__first;
-  _Distance __sz = __k;
-  for (; __first != __last; ++__first, (void) ++__k) {
-    _Distance __r = uniform_int_distribution<_Distance>(0, __k)(__g);
-    if (__r < __sz)
-      __output_iter[__r] = *__first;
-  }
-  return __output_iter + _VSTD::min(__n, __k);
-}
-
-template <class _PopulationIterator, class _SampleIterator, class _Distance,
-          class _UniformRandomNumberGenerator>
-_LIBCPP_INLINE_VISIBILITY
-_SampleIterator __sample(_PopulationIterator __first,
-                         _PopulationIterator __last, _SampleIterator __output_iter,
-                         _Distance __n,
-                         _UniformRandomNumberGenerator& __g,
-                         forward_iterator_tag) {
-  _Distance __unsampled_sz = _VSTD::distance(__first, __last);
-  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
-    _Distance __r = uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
-    if (__r < __n) {
-      *__output_iter++ = *__first;
-      --__n;
-    }
-  }
-  return __output_iter;
-}
-
-template <class _PopulationIterator, class _SampleIterator, class _Distance,
-          class _UniformRandomNumberGenerator>
-_LIBCPP_INLINE_VISIBILITY
-_SampleIterator __sample(_PopulationIterator __first,
-                         _PopulationIterator __last, _SampleIterator __output_iter,
-                         _Distance __n, _UniformRandomNumberGenerator& __g) {
-  typedef typename iterator_traits<_PopulationIterator>::iterator_category
-        _PopCategory;
-  typedef typename iterator_traits<_PopulationIterator>::difference_type
-        _Difference;
-  static_assert(__is_cpp17_forward_iterator<_PopulationIterator>::value ||
-                __is_cpp17_random_access_iterator<_SampleIterator>::value,
-                "SampleIterator must meet the requirements of RandomAccessIterator");
-  typedef typename common_type<_Distance, _Difference>::type _CommonType;
-  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
-  return _VSTD::__sample(
-      __first, __last, __output_iter, _CommonType(__n),
-      __g, _PopCategory());
-}
-
-#if _LIBCPP_STD_VER > 14
-template <class _PopulationIterator, class _SampleIterator, class _Distance,
-          class _UniformRandomNumberGenerator>
-inline _LIBCPP_INLINE_VISIBILITY
-_SampleIterator sample(_PopulationIterator __first,
-                       _PopulationIterator __last, _SampleIterator __output_iter,
-                       _Distance __n, _UniformRandomNumberGenerator&& __g) {
-    return _VSTD::__sample(__first, __last, __output_iter, __n, __g);
-}
-#endif // _LIBCPP_STD_VER > 14
-
-template<class _RandomAccessIterator, class _UniformRandomNumberGenerator>
-    void shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
-                 _UniformRandomNumberGenerator&& __g)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    typedef uniform_int_distribution<ptrdiff_t> _Dp;
-    typedef typename _Dp::param_type _Pp;
-    difference_type __d = __last - __first;
-    if (__d > 1)
-    {
-        _Dp __uid;
-        for (--__last, (void) --__d; __first < __last; ++__first, (void) --__d)
-        {
-            difference_type __i = __uid(__g, _Pp(0, __d));
-            if (__i != difference_type(0))
-                swap(*__first, *(__first + __i));
-        }
-    }
-}
-
-#if _LIBCPP_STD_VER > 17
-
-// shift_left, shift_right
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY constexpr
-_ForwardIterator
-shift_left(_ForwardIterator __first, _ForwardIterator __last,
-           typename iterator_traits<_ForwardIterator>::difference_type __n)
-{
-    if (__n == 0) {
-        return __last;
-    }
-
-    _ForwardIterator __m = __first;
-    if constexpr (__is_cpp17_random_access_iterator<_ForwardIterator>::value) {
-        if (__n >= __last - __first) {
-            return __first;
-        }
-        __m += __n;
-    } else {
-        for (; __n > 0; --__n) {
-            if (__m == __last) {
-                return __first;
-            }
-            ++__m;
-        }
-    }
-    return _VSTD::move(__m, __last, __first);
-}
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY constexpr
-_ForwardIterator
-shift_right(_ForwardIterator __first, _ForwardIterator __last,
-            typename iterator_traits<_ForwardIterator>::difference_type __n)
-{
-    if (__n == 0) {
-        return __first;
-    }
-
-    if constexpr (__is_cpp17_random_access_iterator<_ForwardIterator>::value) {
-        decltype(__n) __d = __last - __first;
-        if (__n >= __d) {
-            return __last;
-        }
-        _ForwardIterator __m = __first + (__d - __n);
-        return _VSTD::move_backward(__first, __m, __last);
-    } else if constexpr (__is_cpp17_bidirectional_iterator<_ForwardIterator>::value) {
-        _ForwardIterator __m = __last;
-        for (; __n > 0; --__n) {
-            if (__m == __first) {
-                return __last;
-            }
-            --__m;
-        }
-        return _VSTD::move_backward(__first, __m, __last);
-    } else {
-        _ForwardIterator __ret = __first;
-        for (; __n > 0; --__n) {
-            if (__ret == __last) {
-                return __last;
-            }
-            ++__ret;
-        }
-
-        // We have an __n-element scratch space from __first to __ret.
-        // Slide an __n-element window [__trail, __lead) from left to right.
-        // We're essentially doing swap_ranges(__first, __ret, __trail, __lead)
-        // over and over; but once __lead reaches __last we needn't bother
-        // to save the values of elements [__trail, __last).
-
-        auto __trail = __first;
-        auto __lead = __ret;
-        while (__trail != __ret) {
-            if (__lead == __last) {
-                _VSTD::move(__first, __trail, __ret);
-                return __ret;
-            }
-            ++__trail;
-            ++__lead;
-        }
-
-        _ForwardIterator __mid = __first;
-        while (true) {
-            if (__lead == __last) {
-                __trail = _VSTD::move(__mid, __ret, __trail);
-                _VSTD::move(__first, __mid, __trail);
-                return __ret;
-            }
-            swap(*__mid, *__trail);
-            ++__mid;
-            ++__trail;
-            ++__lead;
-            if (__mid == __ret) {
-                __mid = __first;
-            }
-        }
-    }
-}
-
-#endif // _LIBCPP_STD_VER > 17
-
-// is_partitioned
-
-template <class _InputIterator, class _Predicate>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-is_partitioned(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-        if (!__pred(*__first))
-            break;
-    if ( __first == __last )
-        return true;
-    ++__first;
-    for (; __first != __last; ++__first)
-        if (__pred(*__first))
-            return false;
-    return true;
-}
-
-// partition
-
-template <class _Predicate, class _ForwardIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-__partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag)
-{
-    while (true)
-    {
-        if (__first == __last)
-            return __first;
-        if (!__pred(*__first))
-            break;
-        ++__first;
-    }
-    for (_ForwardIterator __p = __first; ++__p != __last;)
-    {
-        if (__pred(*__p))
-        {
-            swap(*__first, *__p);
-            ++__first;
-        }
-    }
-    return __first;
-}
-
-template <class _Predicate, class _BidirectionalIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator
-__partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
-            bidirectional_iterator_tag)
-{
-    while (true)
-    {
-        while (true)
-        {
-            if (__first == __last)
-                return __first;
-            if (!__pred(*__first))
-                break;
-            ++__first;
-        }
-        do
-        {
-            if (__first == --__last)
-                return __first;
-        } while (!__pred(*__last));
-        swap(*__first, *__last);
-        ++__first;
-    }
-}
-
-template <class _ForwardIterator, class _Predicate>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
-{
-    return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type>
-                            (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
-}
-
-// partition_copy
-
-template <class _InputIterator, class _OutputIterator1,
-          class _OutputIterator2, class _Predicate>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_OutputIterator1, _OutputIterator2>
-partition_copy(_InputIterator __first, _InputIterator __last,
-               _OutputIterator1 __out_true, _OutputIterator2 __out_false,
-               _Predicate __pred)
-{
-    for (; __first != __last; ++__first)
-    {
-        if (__pred(*__first))
-        {
-            *__out_true = *__first;
-            ++__out_true;
-        }
-        else
-        {
-            *__out_false = *__first;
-            ++__out_false;
-        }
-    }
-    return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
-}
-
-// partition_point
-
-template<class _ForwardIterator, class _Predicate>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
-{
-    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
-    difference_type __len = _VSTD::distance(__first, __last);
-    while (__len != 0)
-    {
-        difference_type __l2 = _VSTD::__half_positive(__len);
-        _ForwardIterator __m = __first;
-        _VSTD::advance(__m, __l2);
-        if (__pred(*__m))
-        {
-            __first = ++__m;
-            __len -= __l2 + 1;
-        }
-        else
-            __len = __l2;
-    }
-    return __first;
-}
-
-// stable_partition
-
-template <class _Predicate, class _ForwardIterator, class _Distance, class _Pair>
-_ForwardIterator
-__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
-                   _Distance __len, _Pair __p, forward_iterator_tag __fit)
-{
-    // *__first is known to be false
-    // __len >= 1
-    if (__len == 1)
-        return __first;
-    if (__len == 2)
-    {
-        _ForwardIterator __m = __first;
-        if (__pred(*++__m))
-        {
-            swap(*__first, *__m);
-            return __m;
-        }
-        return __first;
-    }
-    if (__len <= __p.second)
-    {   // The buffer is big enough to use
-        typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-        __destruct_n __d(0);
-        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
-        // Move the falses into the temporary buffer, and the trues to the front of the line
-        // Update __first to always point to the end of the trues
-        value_type* __t = __p.first;
-        ::new ((void*)__t) value_type(_VSTD::move(*__first));
-        __d.template __incr<value_type>();
-        ++__t;
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-        {
-            if (__pred(*__i))
-            {
-                *__first = _VSTD::move(*__i);
-                ++__first;
-            }
-            else
-            {
-                ::new ((void*)__t) value_type(_VSTD::move(*__i));
-                __d.template __incr<value_type>();
-                ++__t;
-            }
-        }
-        // All trues now at start of range, all falses in buffer
-        // Move falses back into range, but don't mess up __first which points to first false
-        __i = __first;
-        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, (void) ++__i)
-            *__i = _VSTD::move(*__t2);
-        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
-        return __first;
-    }
-    // Else not enough buffer, do in place
-    // __len >= 3
-    _ForwardIterator __m = __first;
-    _Distance __len2 = __len / 2;  // __len2 >= 2
-    _VSTD::advance(__m, __len2);
-    // recurse on [__first, __m), *__first know to be false
-    // F?????????????????
-    // f       m         l
-    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
-    _ForwardIterator __first_false = _VSTD::__stable_partition<_PredRef>(__first, __m, __pred, __len2, __p, __fit);
-    // TTTFFFFF??????????
-    // f  ff   m         l
-    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
-    _ForwardIterator __m1 = __m;
-    _ForwardIterator __second_false = __last;
-    _Distance __len_half = __len - __len2;
-    while (__pred(*__m1))
-    {
-        if (++__m1 == __last)
-            goto __second_half_done;
-        --__len_half;
-    }
-    // TTTFFFFFTTTF??????
-    // f  ff   m  m1     l
-    __second_false = _VSTD::__stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __fit);
-__second_half_done:
-    // TTTFFFFFTTTTTFFFFF
-    // f  ff   m    sf   l
-    return _VSTD::rotate(__first_false, __m, __second_false);
-    // TTTTTTTTFFFFFFFFFF
-    //         |
-}
-
-struct __return_temporary_buffer
-{
-    template <class _Tp>
-    _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
-};
-
-template <class _Predicate, class _ForwardIterator>
-_ForwardIterator
-__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
-                   forward_iterator_tag)
-{
-    const unsigned __alloc_limit = 3;  // might want to make this a function of trivial assignment
-    // Either prove all true and return __first or point to first false
-    while (true)
-    {
-        if (__first == __last)
-            return __first;
-        if (!__pred(*__first))
-            break;
-        ++__first;
-    }
-    // We now have a reduced range [__first, __last)
-    // *__first is known to be false
-    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-    difference_type __len = _VSTD::distance(__first, __last);
-    pair<value_type*, ptrdiff_t> __p(0, 0);
-    unique_ptr<value_type, __return_temporary_buffer> __h;
-    if (__len >= __alloc_limit)
-    {
-        __p = _VSTD::get_temporary_buffer<value_type>(__len);
-        __h.reset(__p.first);
-    }
-    return _VSTD::__stable_partition<typename add_lvalue_reference<_Predicate>::type>
-                             (__first, __last, __pred, __len, __p, forward_iterator_tag());
-}
-
-template <class _Predicate, class _BidirectionalIterator, class _Distance, class _Pair>
-_BidirectionalIterator
-__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
-                   _Distance __len, _Pair __p, bidirectional_iterator_tag __bit)
-{
-    // *__first is known to be false
-    // *__last is known to be true
-    // __len >= 2
-    if (__len == 2)
-    {
-        swap(*__first, *__last);
-        return __last;
-    }
-    if (__len == 3)
-    {
-        _BidirectionalIterator __m = __first;
-        if (__pred(*++__m))
-        {
-            swap(*__first, *__m);
-            swap(*__m, *__last);
-            return __last;
-        }
-        swap(*__m, *__last);
-        swap(*__first, *__m);
-        return __m;
-    }
-    if (__len <= __p.second)
-    {   // The buffer is big enough to use
-        typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-        __destruct_n __d(0);
-        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
-        // Move the falses into the temporary buffer, and the trues to the front of the line
-        // Update __first to always point to the end of the trues
-        value_type* __t = __p.first;
-        ::new ((void*)__t) value_type(_VSTD::move(*__first));
-        __d.template __incr<value_type>();
-        ++__t;
-        _BidirectionalIterator __i = __first;
-        while (++__i != __last)
-        {
-            if (__pred(*__i))
-            {
-                *__first = _VSTD::move(*__i);
-                ++__first;
-            }
-            else
-            {
-                ::new ((void*)__t) value_type(_VSTD::move(*__i));
-                __d.template __incr<value_type>();
-                ++__t;
-            }
-        }
-        // move *__last, known to be true
-        *__first = _VSTD::move(*__i);
-        __i = ++__first;
-        // All trues now at start of range, all falses in buffer
-        // Move falses back into range, but don't mess up __first which points to first false
-        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, (void) ++__i)
-            *__i = _VSTD::move(*__t2);
-        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
-        return __first;
-    }
-    // Else not enough buffer, do in place
-    // __len >= 4
-    _BidirectionalIterator __m = __first;
-    _Distance __len2 = __len / 2;  // __len2 >= 2
-    _VSTD::advance(__m, __len2);
-    // recurse on [__first, __m-1], except reduce __m-1 until *(__m-1) is true, *__first know to be false
-    // F????????????????T
-    // f       m        l
-    _BidirectionalIterator __m1 = __m;
-    _BidirectionalIterator __first_false = __first;
-    _Distance __len_half = __len2;
-    while (!__pred(*--__m1))
-    {
-        if (__m1 == __first)
-            goto __first_half_done;
-        --__len_half;
-    }
-    // F???TFFF?????????T
-    // f   m1  m        l
-    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
-    __first_false = _VSTD::__stable_partition<_PredRef>(__first, __m1, __pred, __len_half, __p, __bit);
-__first_half_done:
-    // TTTFFFFF?????????T
-    // f  ff   m        l
-    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
-    __m1 = __m;
-    _BidirectionalIterator __second_false = __last;
-    ++__second_false;
-    __len_half = __len - __len2;
-    while (__pred(*__m1))
-    {
-        if (++__m1 == __last)
-            goto __second_half_done;
-        --__len_half;
-    }
-    // TTTFFFFFTTTF?????T
-    // f  ff   m  m1    l
-    __second_false = _VSTD::__stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __bit);
-__second_half_done:
-    // TTTFFFFFTTTTTFFFFF
-    // f  ff   m    sf  l
-    return _VSTD::rotate(__first_false, __m, __second_false);
-    // TTTTTTTTFFFFFFFFFF
-    //         |
-}
-
-template <class _Predicate, class _BidirectionalIterator>
-_BidirectionalIterator
-__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
-                   bidirectional_iterator_tag)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    const difference_type __alloc_limit = 4;  // might want to make this a function of trivial assignment
-    // Either prove all true and return __first or point to first false
-    while (true)
-    {
-        if (__first == __last)
-            return __first;
-        if (!__pred(*__first))
-            break;
-        ++__first;
-    }
-    // __first points to first false, everything prior to __first is already set.
-    // Either prove [__first, __last) is all false and return __first, or point __last to last true
-    do
-    {
-        if (__first == --__last)
-            return __first;
-    } while (!__pred(*__last));
-    // We now have a reduced range [__first, __last]
-    // *__first is known to be false
-    // *__last is known to be true
-    // __len >= 2
-    difference_type __len = _VSTD::distance(__first, __last) + 1;
-    pair<value_type*, ptrdiff_t> __p(0, 0);
-    unique_ptr<value_type, __return_temporary_buffer> __h;
-    if (__len >= __alloc_limit)
-    {
-        __p = _VSTD::get_temporary_buffer<value_type>(__len);
-        __h.reset(__p.first);
-    }
-    return _VSTD::__stable_partition<typename add_lvalue_reference<_Predicate>::type>
-                             (__first, __last, __pred, __len, __p, bidirectional_iterator_tag());
-}
-
-template <class _ForwardIterator, class _Predicate>
-inline _LIBCPP_INLINE_VISIBILITY
-_ForwardIterator
-stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
-{
-    return _VSTD::__stable_partition<typename add_lvalue_reference<_Predicate>::type>
-                             (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
-}
-
-// is_sorted_until
-
-template <class _ForwardIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-is_sorted_until(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
-{
-    if (__first != __last)
-    {
-        _ForwardIterator __i = __first;
-        while (++__i != __last)
-        {
-            if (__comp(*__i, *__first))
-                return __i;
-            __first = __i;
-        }
-    }
-    return __last;
-}
-
-template<class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
-{
-    return _VSTD::is_sorted_until(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// is_sorted
-
-template <class _ForwardIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_sorted(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
-{
-    return _VSTD::is_sorted_until(__first, __last, __comp) == __last;
-}
-
-template<class _ForwardIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_sorted(_ForwardIterator __first, _ForwardIterator __last)
-{
-    return _VSTD::is_sorted(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// sort
-
-// stable, 2-3 compares, 0-2 swaps
-
-template <class _Compare, class _ForwardIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 unsigned
-__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
-{
-    unsigned __r = 0;
-    if (!__c(*__y, *__x))          // if x <= y
-    {
-        if (!__c(*__z, *__y))      // if y <= z
-            return __r;            // x <= y && y <= z
-                                   // x <= y && y > z
-        swap(*__y, *__z);          // x <= z && y < z
-        __r = 1;
-        if (__c(*__y, *__x))       // if x > y
-        {
-            swap(*__x, *__y);      // x < y && y <= z
-            __r = 2;
-        }
-        return __r;                // x <= y && y < z
-    }
-    if (__c(*__z, *__y))           // x > y, if y > z
-    {
-        swap(*__x, *__z);          // x < y && y < z
-        __r = 1;
-        return __r;
-    }
-    swap(*__x, *__y);              // x > y && y <= z
-    __r = 1;                       // x < y && x <= z
-    if (__c(*__z, *__y))           // if y > z
-    {
-        swap(*__y, *__z);          // x <= y && y < z
-        __r = 2;
-    }
-    return __r;
-}                                  // x <= y && y <= z
-
-// stable, 3-6 compares, 0-5 swaps
-
-template <class _Compare, class _ForwardIterator>
-unsigned
-__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
-            _ForwardIterator __x4, _Compare __c)
-{
-    unsigned __r = _VSTD::__sort3<_Compare>(__x1, __x2, __x3, __c);
-    if (__c(*__x4, *__x3))
-    {
-        swap(*__x3, *__x4);
-        ++__r;
-        if (__c(*__x3, *__x2))
-        {
-            swap(*__x2, *__x3);
-            ++__r;
-            if (__c(*__x2, *__x1))
-            {
-                swap(*__x1, *__x2);
-                ++__r;
-            }
-        }
-    }
-    return __r;
-}
-
-// stable, 4-10 compares, 0-9 swaps
-
-template <class _Compare, class _ForwardIterator>
-_LIBCPP_HIDDEN
-unsigned
-__sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
-            _ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
-{
-    unsigned __r = _VSTD::__sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
-    if (__c(*__x5, *__x4))
-    {
-        swap(*__x4, *__x5);
-        ++__r;
-        if (__c(*__x4, *__x3))
-        {
-            swap(*__x3, *__x4);
-            ++__r;
-            if (__c(*__x3, *__x2))
-            {
-                swap(*__x2, *__x3);
-                ++__r;
-                if (__c(*__x2, *__x1))
-                {
-                    swap(*__x1, *__x2);
-                    ++__r;
-                }
-            }
-        }
-    }
-    return __r;
-}
-
-// Assumes size > 0
-template <class _Compare, class _BidirectionalIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 void
-__selection_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
-{
-    _BidirectionalIterator __lm1 = __last;
-    for (--__lm1; __first != __lm1; ++__first)
-    {
-        _BidirectionalIterator __i = _VSTD::min_element<_BidirectionalIterator,
-                                                        typename add_lvalue_reference<_Compare>::type>
-                                                       (__first, __last, __comp);
-        if (__i != __first)
-            swap(*__first, *__i);
-    }
-}
-
-template <class _Compare, class _BidirectionalIterator>
-void
-__insertion_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    if (__first != __last)
-    {
-        _BidirectionalIterator __i = __first;
-        for (++__i; __i != __last; ++__i)
-        {
-            _BidirectionalIterator __j = __i;
-            value_type __t(_VSTD::move(*__j));
-            for (_BidirectionalIterator __k = __i; __k != __first && __comp(__t,  *--__k); --__j)
-                *__j = _VSTD::move(*__k);
-            *__j = _VSTD::move(__t);
-        }
-    }
-}
-
-template <class _Compare, class _RandomAccessIterator>
-void
-__insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    _RandomAccessIterator __j = __first+2;
-    _VSTD::__sort3<_Compare>(__first, __first+1, __j, __comp);
-    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
-    {
-        if (__comp(*__i, *__j))
-        {
-            value_type __t(_VSTD::move(*__i));
-            _RandomAccessIterator __k = __j;
-            __j = __i;
-            do
-            {
-                *__j = _VSTD::move(*__k);
-                __j = __k;
-            } while (__j != __first && __comp(__t, *--__k));
-            *__j = _VSTD::move(__t);
-        }
-        __j = __i;
-    }
-}
-
-template <class _Compare, class _RandomAccessIterator>
-bool
-__insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    switch (__last - __first)
-    {
-    case 0:
-    case 1:
-        return true;
-    case 2:
-        if (__comp(*--__last, *__first))
-            swap(*__first, *__last);
-        return true;
-    case 3:
-        _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
-        return true;
-    case 4:
-        _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
-        return true;
-    case 5:
-        _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
-        return true;
-    }
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    _RandomAccessIterator __j = __first+2;
-    _VSTD::__sort3<_Compare>(__first, __first+1, __j, __comp);
-    const unsigned __limit = 8;
-    unsigned __count = 0;
-    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
-    {
-        if (__comp(*__i, *__j))
-        {
-            value_type __t(_VSTD::move(*__i));
-            _RandomAccessIterator __k = __j;
-            __j = __i;
-            do
-            {
-                *__j = _VSTD::move(*__k);
-                __j = __k;
-            } while (__j != __first && __comp(__t, *--__k));
-            *__j = _VSTD::move(__t);
-            if (++__count == __limit)
-                return ++__i == __last;
-        }
-        __j = __i;
-    }
-    return true;
-}
-
-template <class _Compare, class _BidirectionalIterator>
-void
-__insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
-                      typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    if (__first1 != __last1)
-    {
-        __destruct_n __d(0);
-        unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
-        value_type* __last2 = __first2;
-        ::new ((void*)__last2) value_type(_VSTD::move(*__first1));
-        __d.template __incr<value_type>();
-        for (++__last2; ++__first1 != __last1; ++__last2)
-        {
-            value_type* __j2 = __last2;
-            value_type* __i2 = __j2;
-            if (__comp(*__first1, *--__i2))
-            {
-                ::new ((void*)__j2) value_type(_VSTD::move(*__i2));
-                __d.template __incr<value_type>();
-                for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
-                    *__j2 = _VSTD::move(*__i2);
-                *__j2 = _VSTD::move(*__first1);
-            }
-            else
-            {
-                ::new ((void*)__j2) value_type(_VSTD::move(*__first1));
-                __d.template __incr<value_type>();
-            }
-        }
-        __h.release();
-    }
-}
-
-template <class _Compare, class _RandomAccessIterator>
-void
-__sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
-                                    is_trivially_copy_assignable<value_type>::value ? 30 : 6;
-    while (true)
-    {
-    __restart:
-        difference_type __len = __last - __first;
-        switch (__len)
-        {
-        case 0:
-        case 1:
-            return;
-        case 2:
-            if (__comp(*--__last, *__first))
-                swap(*__first, *__last);
-            return;
-        case 3:
-            _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
-            return;
-        case 4:
-            _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
-            return;
-        case 5:
-            _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
-            return;
-        }
-        if (__len <= __limit)
-        {
-            _VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
-            return;
-        }
-        // __len > 5
-        _RandomAccessIterator __m = __first;
-        _RandomAccessIterator __lm1 = __last;
-        --__lm1;
-        unsigned __n_swaps;
-        {
-        difference_type __delta;
-        if (__len >= 1000)
-        {
-            __delta = __len/2;
-            __m += __delta;
-            __delta /= 2;
-            __n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
-        }
-        else
-        {
-            __delta = __len/2;
-            __m += __delta;
-            __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
-        }
-        }
-        // *__m is median
-        // partition [__first, __m) < *__m and *__m <= [__m, __last)
-        // (this inhibits tossing elements equivalent to __m around unnecessarily)
-        _RandomAccessIterator __i = __first;
-        _RandomAccessIterator __j = __lm1;
-        // j points beyond range to be tested, *__m is known to be <= *__lm1
-        // The search going up is known to be guarded but the search coming down isn't.
-        // Prime the downward search with a guard.
-        if (!__comp(*__i, *__m))  // if *__first == *__m
-        {
-            // *__first == *__m, *__first doesn't go in first part
-            // manually guard downward moving __j against __i
-            while (true)
-            {
-                if (__i == --__j)
-                {
-                    // *__first == *__m, *__m <= all other elements
-                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
-                    ++__i;  // __first + 1
-                    __j = __last;
-                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
-                    {
-                        while (true)
-                        {
-                            if (__i == __j)
-                                return;  // [__first, __last) all equivalent elements
-                            if (__comp(*__first, *__i))
-                            {
-                                swap(*__i, *__j);
-                                ++__n_swaps;
-                                ++__i;
-                                break;
-                            }
-                            ++__i;
-                        }
-                    }
-                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
-                    if (__i == __j)
-                        return;
-                    while (true)
-                    {
-                        while (!__comp(*__first, *__i))
-                            ++__i;
-                        while (__comp(*__first, *--__j))
-                            ;
-                        if (__i >= __j)
-                            break;
-                        swap(*__i, *__j);
-                        ++__n_swaps;
-                        ++__i;
-                    }
-                    // [__first, __i) == *__first and *__first < [__i, __last)
-                    // The first part is sorted, sort the second part
-                    // _VSTD::__sort<_Compare>(__i, __last, __comp);
-                    __first = __i;
-                    goto __restart;
-                }
-                if (__comp(*__j, *__m))
-                {
-                    swap(*__i, *__j);
-                    ++__n_swaps;
-                    break;  // found guard for downward moving __j, now use unguarded partition
-                }
-            }
-        }
-        // It is known that *__i < *__m
-        ++__i;
-        // j points beyond range to be tested, *__m is known to be <= *__lm1
-        // if not yet partitioned...
-        if (__i < __j)
-        {
-            // known that *(__i - 1) < *__m
-            // known that __i <= __m
-            while (true)
-            {
-                // __m still guards upward moving __i
-                while (__comp(*__i, *__m))
-                    ++__i;
-                // It is now known that a guard exists for downward moving __j
-                while (!__comp(*--__j, *__m))
-                    ;
-                if (__i > __j)
-                    break;
-                swap(*__i, *__j);
-                ++__n_swaps;
-                // It is known that __m != __j
-                // If __m just moved, follow it
-                if (__m == __i)
-                    __m = __j;
-                ++__i;
-            }
-        }
-        // [__first, __i) < *__m and *__m <= [__i, __last)
-        if (__i != __m && __comp(*__m, *__i))
-        {
-            swap(*__i, *__m);
-            ++__n_swaps;
-        }
-        // [__first, __i) < *__i and *__i <= [__i+1, __last)
-        // If we were given a perfect partition, see if insertion sort is quick...
-        if (__n_swaps == 0)
-        {
-            bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
-            if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+1, __last, __comp))
-            {
-                if (__fs)
-                    return;
-                __last = __i;
-                continue;
-            }
-            else
-            {
-                if (__fs)
-                {
-                    __first = ++__i;
-                    continue;
-                }
-            }
-        }
-        // sort smaller range with recursive call and larger with tail recursion elimination
-        if (__i - __first < __last - __i)
-        {
-            _VSTD::__sort<_Compare>(__first, __i, __comp);
-            // _VSTD::__sort<_Compare>(__i+1, __last, __comp);
-            __first = ++__i;
-        }
-        else
-        {
-            _VSTD::__sort<_Compare>(__i+1, __last, __comp);
-            // _VSTD::__sort<_Compare>(__first, __i, __comp);
-            __last = __i;
-        }
-    }
-}
-
-template <class _Compare, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-__sort(_Tp** __first, _Tp** __last, __less<_Tp*>&)
-{
-    __less<uintptr_t> __comp;
-    _VSTD::__sort<__less<uintptr_t>&, uintptr_t*>((uintptr_t*)__first, (uintptr_t*)__last, __comp);
-}
-
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
-
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
-
-_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&))
-
-// lower_bound
-
-template <class _Compare, class _ForwardIterator, class _Tp>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-__lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
-    difference_type __len = _VSTD::distance(__first, __last);
-    while (__len != 0)
-    {
-        difference_type __l2 = _VSTD::__half_positive(__len);
-        _ForwardIterator __m = __first;
-        _VSTD::advance(__m, __l2);
-        if (__comp(*__m, __value_))
-        {
-            __first = ++__m;
-            __len -= __l2 + 1;
-        }
-        else
-            __len = __l2;
-    }
-    return __first;
-}
-
-template <class _ForwardIterator, class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
-    return _VSTD::__lower_bound<_Comp_ref>(__first, __last, __value_, __comp);
-}
-
-template <class _ForwardIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
-{
-    return _VSTD::lower_bound(__first, __last, __value_,
-                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
-}
-
-// upper_bound
-
-template <class _Compare, class _ForwardIterator, class _Tp>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
-__upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
-    difference_type __len = _VSTD::distance(__first, __last);
-    while (__len != 0)
-    {
-        difference_type __l2 = _VSTD::__half_positive(__len);
-        _ForwardIterator __m = __first;
-        _VSTD::advance(__m, __l2);
-        if (__comp(__value_, *__m))
-            __len = __l2;
-        else
-        {
-            __first = ++__m;
-            __len -= __l2 + 1;
-        }
-    }
-    return __first;
-}
-
-template <class _ForwardIterator, class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
-    return _VSTD::__upper_bound<_Comp_ref>(__first, __last, __value_, __comp);
-}
-
-template <class _ForwardIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator
-upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
-{
-    return _VSTD::upper_bound(__first, __last, __value_,
-                             __less<_Tp, typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// equal_range
-
-template <class _Compare, class _ForwardIterator, class _Tp>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
-__equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
-    difference_type __len = _VSTD::distance(__first, __last);
-    while (__len != 0)
-    {
-        difference_type __l2 = _VSTD::__half_positive(__len);
-        _ForwardIterator __m = __first;
-        _VSTD::advance(__m, __l2);
-        if (__comp(*__m, __value_))
-        {
-            __first = ++__m;
-            __len -= __l2 + 1;
-        }
-        else if (__comp(__value_, *__m))
-        {
-            __last = __m;
-            __len = __l2;
-        }
-        else
-        {
-            _ForwardIterator __mp1 = __m;
-            return pair<_ForwardIterator, _ForwardIterator>
-                   (
-                      _VSTD::__lower_bound<_Compare>(__first, __m, __value_, __comp),
-                      _VSTD::__upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
-                   );
-        }
-    }
-    return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
-}
-
-template <class _ForwardIterator, class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-pair<_ForwardIterator, _ForwardIterator>
-equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__equal_range<_Comp_ref>(__first, __last, __value_, __comp);
-}
-
-template <class _ForwardIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-pair<_ForwardIterator, _ForwardIterator>
-equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
-{
-    return _VSTD::equal_range(__first, __last, __value_,
-                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
-}
-
-// binary_search
-
-template <class _Compare, class _ForwardIterator, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-__binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    __first = _VSTD::__lower_bound<_Compare>(__first, __last, __value_, __comp);
-    return __first != __last && !__comp(__value_, *__first);
-}
-
-template <class _ForwardIterator, class _Tp, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__binary_search<_Comp_ref>(__first, __last, __value_, __comp);
-}
-
-template <class _ForwardIterator, class _Tp>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
-{
-    return _VSTD::binary_search(__first, __last, __value_,
-                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
-}
-
-// merge
-
-template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-__merge(_InputIterator1 __first1, _InputIterator1 __last1,
-        _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    for (; __first1 != __last1; ++__result)
-    {
-        if (__first2 == __last2)
-            return _VSTD::copy(__first1, __last1, __result);
-        if (__comp(*__first2, *__first1))
-        {
-            *__result = *__first2;
-            ++__first2;
-        }
-        else
-        {
-            *__result = *__first1;
-            ++__first1;
-        }
-    }
-    return _VSTD::copy(__first2, __last2, __result);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-merge(_InputIterator1 __first1, _InputIterator1 __last1,
-      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__merge<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-merge(_InputIterator1 __first1, _InputIterator1 __last1,
-      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
-{
-    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
-    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
-    return _VSTD::merge(__first1, __last1, __first2, __last2, __result, __less<__v1, __v2>());
-}
-
-// inplace_merge
-
-template <class _Compare, class _InputIterator1, class _InputIterator2,
-          class _OutputIterator>
-void __half_inplace_merge(_InputIterator1 __first1, _InputIterator1 __last1,
-                          _InputIterator2 __first2, _InputIterator2 __last2,
-                          _OutputIterator __result, _Compare __comp)
-{
-    for (; __first1 != __last1; ++__result)
-    {
-        if (__first2 == __last2)
-        {
-            _VSTD::move(__first1, __last1, __result);
-            return;
-        }
-
-        if (__comp(*__first2, *__first1))
-        {
-            *__result = _VSTD::move(*__first2);
-            ++__first2;
-        }
-        else
-        {
-            *__result = _VSTD::move(*__first1);
-            ++__first1;
-        }
-    }
-    // __first2 through __last2 are already in the right spot.
-}
-
-template <class _Compare, class _BidirectionalIterator>
-void
-__buffered_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
-                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
-                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
-                typename iterator_traits<_BidirectionalIterator>::value_type* __buff)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    __destruct_n __d(0);
-    unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
-    if (__len1 <= __len2)
-    {
-        value_type* __p = __buff;
-        for (_BidirectionalIterator __i = __first; __i != __middle; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
-            ::new ((void*)__p) value_type(_VSTD::move(*__i));
-        _VSTD::__half_inplace_merge<_Compare>(__buff, __p, __middle, __last, __first, __comp);
-    }
-    else
-    {
-        value_type* __p = __buff;
-        for (_BidirectionalIterator __i = __middle; __i != __last; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
-            ::new ((void*)__p) value_type(_VSTD::move(*__i));
-        typedef reverse_iterator<_BidirectionalIterator> _RBi;
-        typedef reverse_iterator<value_type*> _Rv;
-        typedef __invert<_Compare> _Inverted;
-        _VSTD::__half_inplace_merge<_Inverted>(_Rv(__p), _Rv(__buff),
-                                    _RBi(__middle), _RBi(__first),
-                                    _RBi(__last), _Inverted(__comp));
-    }
-}
-
-template <class _Compare, class _BidirectionalIterator>
-void
-__inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
-                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
-                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
-                typename iterator_traits<_BidirectionalIterator>::value_type* __buff, ptrdiff_t __buff_size)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
-    while (true)
-    {
-        // if __middle == __last, we're done
-        if (__len2 == 0)
-            return;
-        if (__len1 <= __buff_size || __len2 <= __buff_size)
-            return _VSTD::__buffered_inplace_merge<_Compare>
-                   (__first, __middle, __last, __comp, __len1, __len2, __buff);
-        // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
-        for (; true; ++__first, (void) --__len1)
-        {
-            if (__len1 == 0)
-                return;
-            if (__comp(*__middle, *__first))
-                break;
-        }
-        // __first < __middle < __last
-        // *__first > *__middle
-        // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
-        //     all elements in:
-        //         [__first, __m1)  <= [__middle, __m2)
-        //         [__middle, __m2) <  [__m1, __middle)
-        //         [__m1, __middle) <= [__m2, __last)
-        //     and __m1 or __m2 is in the middle of its range
-        _BidirectionalIterator __m1;  // "median" of [__first, __middle)
-        _BidirectionalIterator __m2;  // "median" of [__middle, __last)
-        difference_type __len11;      // distance(__first, __m1)
-        difference_type __len21;      // distance(__middle, __m2)
-        // binary search smaller range
-        if (__len1 < __len2)
-        {   // __len >= 1, __len2 >= 2
-            __len21 = __len2 / 2;
-            __m2 = __middle;
-            _VSTD::advance(__m2, __len21);
-            __m1 = _VSTD::__upper_bound<_Compare>(__first, __middle, *__m2, __comp);
-            __len11 = _VSTD::distance(__first, __m1);
-        }
-        else
-        {
-            if (__len1 == 1)
-            {   // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
-                // It is known *__first > *__middle
-                swap(*__first, *__middle);
-                return;
-            }
-            // __len1 >= 2, __len2 >= 1
-            __len11 = __len1 / 2;
-            __m1 = __first;
-            _VSTD::advance(__m1, __len11);
-            __m2 = _VSTD::__lower_bound<_Compare>(__middle, __last, *__m1, __comp);
-            __len21 = _VSTD::distance(__middle, __m2);
-        }
-        difference_type __len12 = __len1 - __len11;  // distance(__m1, __middle)
-        difference_type __len22 = __len2 - __len21;  // distance(__m2, __last)
-        // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
-        // swap middle two partitions
-        __middle = _VSTD::rotate(__m1, __middle, __m2);
-        // __len12 and __len21 now have swapped meanings
-        // merge smaller range with recursive call and larger with tail recursion elimination
-        if (__len11 + __len21 < __len12 + __len22)
-        {
-            _VSTD::__inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
-//          _VSTD::__inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
-            __first = __middle;
-            __middle = __m2;
-            __len1 = __len12;
-            __len2 = __len22;
-        }
-        else
-        {
-            _VSTD::__inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
-//          _VSTD::__inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
-            __last = __middle;
-            __middle = __m1;
-            __len1 = __len11;
-            __len2 = __len21;
-        }
-    }
-}
-
-template <class _BidirectionalIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
-              _Compare __comp)
-{
-    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
-    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
-    difference_type __len1 = _VSTD::distance(__first, __middle);
-    difference_type __len2 = _VSTD::distance(__middle, __last);
-    difference_type __buf_size = _VSTD::min(__len1, __len2);
-    pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
-    unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __comp, __len1, __len2,
-                                            __buf.first, __buf.second);
-}
-
-template <class _BidirectionalIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last)
-{
-    _VSTD::inplace_merge(__first, __middle, __last,
-                        __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
-}
-
-// stable_sort
-
-template <class _Compare, class _InputIterator1, class _InputIterator2>
-void
-__merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
-        _InputIterator2 __first2, _InputIterator2 __last2,
-        typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
-{
-    typedef typename iterator_traits<_InputIterator1>::value_type value_type;
-    __destruct_n __d(0);
-    unique_ptr<value_type, __destruct_n&> __h(__result, __d);
-    for (; true; ++__result)
-    {
-        if (__first1 == __last1)
-        {
-            for (; __first2 != __last2; ++__first2, ++__result, (void)__d.template __incr<value_type>())
-                ::new ((void*)__result) value_type(_VSTD::move(*__first2));
-            __h.release();
-            return;
-        }
-        if (__first2 == __last2)
-        {
-            for (; __first1 != __last1; ++__first1, ++__result, (void)__d.template __incr<value_type>())
-                ::new ((void*)__result) value_type(_VSTD::move(*__first1));
-            __h.release();
-            return;
-        }
-        if (__comp(*__first2, *__first1))
-        {
-            ::new ((void*)__result) value_type(_VSTD::move(*__first2));
-            __d.template __incr<value_type>();
-            ++__first2;
-        }
-        else
-        {
-            ::new ((void*)__result) value_type(_VSTD::move(*__first1));
-            __d.template __incr<value_type>();
-            ++__first1;
-        }
-    }
-}
-
-template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
-void
-__merge_move_assign(_InputIterator1 __first1, _InputIterator1 __last1,
-        _InputIterator2 __first2, _InputIterator2 __last2,
-        _OutputIterator __result, _Compare __comp)
-{
-    for (; __first1 != __last1; ++__result)
-    {
-        if (__first2 == __last2)
-        {
-            for (; __first1 != __last1; ++__first1, (void) ++__result)
-                *__result = _VSTD::move(*__first1);
-            return;
-        }
-        if (__comp(*__first2, *__first1))
-        {
-            *__result = _VSTD::move(*__first2);
-            ++__first2;
-        }
-        else
-        {
-            *__result = _VSTD::move(*__first1);
-            ++__first1;
-        }
-    }
-    for (; __first2 != __last2; ++__first2, (void) ++__result)
-        *__result = _VSTD::move(*__first2);
-}
-
-template <class _Compare, class _RandomAccessIterator>
-void
-__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
-              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size);
-
-template <class _Compare, class _RandomAccessIterator>
-void
-__stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Compare __comp,
-                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-                   typename iterator_traits<_RandomAccessIterator>::value_type* __first2)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    switch (__len)
-    {
-    case 0:
-        return;
-    case 1:
-        ::new ((void*)__first2) value_type(_VSTD::move(*__first1));
-        return;
-    case 2:
-        __destruct_n __d(0);
-        unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
-        if (__comp(*--__last1, *__first1))
-        {
-            ::new ((void*)__first2) value_type(_VSTD::move(*__last1));
-            __d.template __incr<value_type>();
-            ++__first2;
-            ::new ((void*)__first2) value_type(_VSTD::move(*__first1));
-        }
-        else
-        {
-            ::new ((void*)__first2) value_type(_VSTD::move(*__first1));
-            __d.template __incr<value_type>();
-            ++__first2;
-            ::new ((void*)__first2) value_type(_VSTD::move(*__last1));
-        }
-        __h2.release();
-        return;
-    }
-    if (__len <= 8)
-    {
-        _VSTD::__insertion_sort_move<_Compare>(__first1, __last1, __first2, __comp);
-        return;
-    }
-    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
-    _RandomAccessIterator __m = __first1 + __l2;
-    _VSTD::__stable_sort<_Compare>(__first1, __m, __comp, __l2, __first2, __l2);
-    _VSTD::__stable_sort<_Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
-    _VSTD::__merge_move_construct<_Compare>(__first1, __m, __m, __last1, __first2, __comp);
-}
-
-template <class _Tp>
-struct __stable_sort_switch
-{
-    static const unsigned value = 128*is_trivially_copy_assignable<_Tp>::value;
-};
-
-template <class _Compare, class _RandomAccessIterator>
-void
-__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
-              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    switch (__len)
-    {
-    case 0:
-    case 1:
-        return;
-    case 2:
-        if (__comp(*--__last, *__first))
-            swap(*__first, *__last);
-        return;
-    }
-    if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value))
-    {
-        _VSTD::__insertion_sort<_Compare>(__first, __last, __comp);
-        return;
-    }
-    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
-    _RandomAccessIterator __m = __first + __l2;
-    if (__len <= __buff_size)
-    {
-        __destruct_n __d(0);
-        unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
-        _VSTD::__stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
-        __d.__set(__l2, (value_type*)nullptr);
-        _VSTD::__stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
-        __d.__set(__len, (value_type*)nullptr);
-        _VSTD::__merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
-//         _VSTD::__merge<_Compare>(move_iterator<value_type*>(__buff),
-//                                  move_iterator<value_type*>(__buff + __l2),
-//                                  move_iterator<_RandomAccessIterator>(__buff + __l2),
-//                                  move_iterator<_RandomAccessIterator>(__buff + __len),
-//                                  __first, __comp);
-        return;
-    }
-    _VSTD::__stable_sort<_Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
-    _VSTD::__stable_sort<_Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
-    _VSTD::__inplace_merge<_Compare>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    difference_type __len = __last - __first;
-    pair<value_type*, ptrdiff_t> __buf(0, 0);
-    unique_ptr<value_type, __return_temporary_buffer> __h;
-    if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value))
-    {
-        __buf = _VSTD::get_temporary_buffer<value_type>(__len);
-        __h.reset(__buf.first);
-    }
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__stable_sort<_Comp_ref>(__first, __last, __comp, __len, __buf.first, __buf.second);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    _VSTD::stable_sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// is_heap_until
-
-template <class _RandomAccessIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
-is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    difference_type __len = __last - __first;
-    difference_type __p = 0;
-    difference_type __c = 1;
-    _RandomAccessIterator __pp = __first;
-    while (__c < __len)
-    {
-        _RandomAccessIterator __cp = __first + __c;
-        if (__comp(*__pp, *__cp))
-            return __cp;
-        ++__c;
-        ++__cp;
-        if (__c == __len)
-            return __last;
-        if (__comp(*__pp, *__cp))
-            return __cp;
-        ++__p;
-        ++__pp;
-        __c = 2 * __p + 1;
-    }
-    return __last;
-}
-
-template<class _RandomAccessIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_RandomAccessIterator
-is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    return _VSTD::is_heap_until(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// is_heap
-
-template <class _RandomAccessIterator, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    return _VSTD::is_heap_until(__first, __last, __comp) == __last;
-}
-
-template<class _RandomAccessIterator>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    return _VSTD::is_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// push_heap
-
-template <class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 void
-__sift_up(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
-          typename iterator_traits<_RandomAccessIterator>::difference_type __len)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    if (__len > 1)
-    {
-        __len = (__len - 2) / 2;
-        _RandomAccessIterator __ptr = __first + __len;
-        if (__comp(*__ptr, *--__last))
-        {
-            value_type __t(_VSTD::move(*__last));
-            do
-            {
-                *__last = _VSTD::move(*__ptr);
-                __last = __ptr;
-                if (__len == 0)
-                    break;
-                __len = (__len - 1) / 2;
-                __ptr = __first + __len;
-            } while (__comp(*__ptr, __t));
-            *__last = _VSTD::move(__t);
-        }
-    }
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__sift_up<_Comp_ref>(__first, __last, __comp, __last - __first);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    _VSTD::push_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// pop_heap
-
-template <class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 void
-__sift_down(_RandomAccessIterator __first, _RandomAccessIterator /*__last*/,
-            _Compare __comp,
-            typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-            _RandomAccessIterator __start)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
-    // left-child of __start is at 2 * __start + 1
-    // right-child of __start is at 2 * __start + 2
-    difference_type __child = __start - __first;
-
-    if (__len < 2 || (__len - 2) / 2 < __child)
-        return;
-
-    __child = 2 * __child + 1;
-    _RandomAccessIterator __child_i = __first + __child;
-
-    if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
-        // right-child exists and is greater than left-child
-        ++__child_i;
-        ++__child;
-    }
-
-    // check if we are in heap-order
-    if (__comp(*__child_i, *__start))
-        // we are, __start is larger than it's largest child
-        return;
-
-    value_type __top(_VSTD::move(*__start));
-    do
-    {
-        // we are not in heap-order, swap the parent with its largest child
-        *__start = _VSTD::move(*__child_i);
-        __start = __child_i;
-
-        if ((__len - 2) / 2 < __child)
-            break;
-
-        // recompute the child based off of the updated parent
-        __child = 2 * __child + 1;
-        __child_i = __first + __child;
-
-        if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
-            // right-child exists and is greater than left-child
-            ++__child_i;
-            ++__child;
-        }
-
-        // check if we are in heap-order
-    } while (!__comp(*__child_i, __top));
-    *__start = _VSTD::move(__top);
-}
-
-template <class _Compare, class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-__pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
-           typename iterator_traits<_RandomAccessIterator>::difference_type __len)
-{
-    if (__len > 1)
-    {
-        swap(*__first, *--__last);
-        _VSTD::__sift_down<_Compare>(__first, __last, __comp, __len - 1, __first);
-    }
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__pop_heap<_Comp_ref>(__first, __last, __comp, __last - __first);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    _VSTD::pop_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// make_heap
-
-template <class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 void
-__make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    difference_type __n = __last - __first;
-    if (__n > 1)
-    {
-        // start from the first parent, there is no need to consider children
-        for (difference_type __start = (__n - 2) / 2; __start >= 0; --__start)
-        {
-            _VSTD::__sift_down<_Compare>(__first, __last, __comp, __n, __first + __start);
-        }
-    }
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__make_heap<_Comp_ref>(__first, __last, __comp);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    _VSTD::make_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// sort_heap
-
-template <class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 void
-__sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    for (difference_type __n = __last - __first; __n > 1; --__last, (void) --__n)
-        _VSTD::__pop_heap<_Compare>(__first, __last, __comp, __n);
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__sort_heap<_Comp_ref>(__first, __last, __comp);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    _VSTD::sort_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// partial_sort
-
-template <class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 void
-__partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
-             _Compare __comp)
-{
-    _VSTD::__make_heap<_Compare>(__first, __middle, __comp);
-    typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
-    for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
-    {
-        if (__comp(*__i, *__first))
-        {
-            swap(*__i, *__first);
-            _VSTD::__sift_down<_Compare>(__first, __middle, __comp, __len, __first);
-        }
-    }
-    _VSTD::__sort_heap<_Compare>(__first, __middle, __comp);
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
-             _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
-{
-    _VSTD::partial_sort(__first, __middle, __last,
-                       __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// partial_sort_copy
-
-template <class _Compare, class _InputIterator, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
-__partial_sort_copy(_InputIterator __first, _InputIterator __last,
-                    _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
-{
-    _RandomAccessIterator __r = __result_first;
-    if (__r != __result_last)
-    {
-        for (; __first != __last && __r != __result_last; ++__first, (void) ++__r)
-            *__r = *__first;
-        _VSTD::__make_heap<_Compare>(__result_first, __r, __comp);
-        typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
-        for (; __first != __last; ++__first)
-            if (__comp(*__first, *__result_first))
-            {
-                *__result_first = *__first;
-                _VSTD::__sift_down<_Compare>(__result_first, __r, __comp, __len, __result_first);
-            }
-        _VSTD::__sort_heap<_Compare>(__result_first, __r, __comp);
-    }
-    return __r;
-}
-
-template <class _InputIterator, class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_RandomAccessIterator
-partial_sort_copy(_InputIterator __first, _InputIterator __last,
-                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __comp);
-}
-
-template <class _InputIterator, class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_RandomAccessIterator
-partial_sort_copy(_InputIterator __first, _InputIterator __last,
-                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
-{
-    return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
-                                   __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// nth_element
-
-template<class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 bool
-__nth_element_find_guard(_RandomAccessIterator& __i, _RandomAccessIterator& __j,
-                         _RandomAccessIterator __m, _Compare __comp)
-{
-    // manually guard downward moving __j against __i
-    while (true) {
-        if (__i == --__j) {
-            return false;
-        }
-        if (__comp(*__j, *__m)) {
-            return true;  // found guard for downward moving __j, now use unguarded partition
-        }
-    }
-}
-
-template <class _Compare, class _RandomAccessIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX11 void
-__nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
-{
-    // _Compare is known to be a reference type
-    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-    const difference_type __limit = 7;
-    while (true)
-    {
-        if (__nth == __last)
-            return;
-        difference_type __len = __last - __first;
-        switch (__len)
-        {
-        case 0:
-        case 1:
-            return;
-        case 2:
-            if (__comp(*--__last, *__first))
-                swap(*__first, *__last);
-            return;
-        case 3:
-            {
-            _RandomAccessIterator __m = __first;
-            _VSTD::__sort3<_Compare>(__first, ++__m, --__last, __comp);
-            return;
-            }
-        }
-        if (__len <= __limit)
-        {
-            _VSTD::__selection_sort<_Compare>(__first, __last, __comp);
-            return;
-        }
-        // __len > __limit >= 3
-        _RandomAccessIterator __m = __first + __len/2;
-        _RandomAccessIterator __lm1 = __last;
-        unsigned __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, --__lm1, __comp);
-        // *__m is median
-        // partition [__first, __m) < *__m and *__m <= [__m, __last)
-        // (this inhibits tossing elements equivalent to __m around unnecessarily)
-        _RandomAccessIterator __i = __first;
-        _RandomAccessIterator __j = __lm1;
-        // j points beyond range to be tested, *__lm1 is known to be <= *__m
-        // The search going up is known to be guarded but the search coming down isn't.
-        // Prime the downward search with a guard.
-        if (!__comp(*__i, *__m))  // if *__first == *__m
-        {
-            // *__first == *__m, *__first doesn't go in first part
-            if (_VSTD::__nth_element_find_guard<_Compare>(__i, __j, __m, __comp)) {
-                swap(*__i, *__j);
-                ++__n_swaps;
-            } else {
-                // *__first == *__m, *__m <= all other elements
-                // Partition instead into [__first, __i) == *__first and *__first < [__i, __last)
-                ++__i;  // __first + 1
-                __j = __last;
-                if (!__comp(*__first, *--__j)) {  // we need a guard if *__first == *(__last-1)
-                    while (true) {
-                        if (__i == __j) {
-                            return;  // [__first, __last) all equivalent elements
-                        } else if (__comp(*__first, *__i)) {
-                            swap(*__i, *__j);
-                            ++__n_swaps;
-                            ++__i;
-                            break;
-                        }
-                        ++__i;
-                    }
-                }
-                // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
-                if (__i == __j) {
-                    return;
-                }
-                while (true) {
-                    while (!__comp(*__first, *__i))
-                        ++__i;
-                    while (__comp(*__first, *--__j))
-                        ;
-                    if (__i >= __j)
-                        break;
-                    swap(*__i, *__j);
-                    ++__n_swaps;
-                    ++__i;
-                }
-                // [__first, __i) == *__first and *__first < [__i, __last)
-                // The first part is sorted,
-                if (__nth < __i) {
-                    return;
-                }
-                // __nth_element the second part
-                // _VSTD::__nth_element<_Compare>(__i, __nth, __last, __comp);
-                __first = __i;
-                continue;
-            }
-        }
-        ++__i;
-        // j points beyond range to be tested, *__lm1 is known to be <= *__m
-        // if not yet partitioned...
-        if (__i < __j)
-        {
-            // known that *(__i - 1) < *__m
-            while (true)
-            {
-                // __m still guards upward moving __i
-                while (__comp(*__i, *__m))
-                    ++__i;
-                // It is now known that a guard exists for downward moving __j
-                while (!__comp(*--__j, *__m))
-                    ;
-                if (__i >= __j)
-                    break;
-                swap(*__i, *__j);
-                ++__n_swaps;
-                // It is known that __m != __j
-                // If __m just moved, follow it
-                if (__m == __i)
-                    __m = __j;
-                ++__i;
-            }
-        }
-        // [__first, __i) < *__m and *__m <= [__i, __last)
-        if (__i != __m && __comp(*__m, *__i))
-        {
-            swap(*__i, *__m);
-            ++__n_swaps;
-        }
-        // [__first, __i) < *__i and *__i <= [__i+1, __last)
-        if (__nth == __i)
-            return;
-        if (__n_swaps == 0)
-        {
-            // We were given a perfectly partitioned sequence.  Coincidence?
-            if (__nth < __i)
-            {
-                // Check for [__first, __i) already sorted
-                __j = __m = __first;
-                while (true) {
-                    if (++__j == __i) {
-                        // [__first, __i) sorted
-                        return;
-                    }
-                    if (__comp(*__j, *__m)) {
-                        // not yet sorted, so sort
-                        break;
-                    }
-                    __m = __j;
-                }
-            }
-            else
-            {
-                // Check for [__i, __last) already sorted
-                __j = __m = __i;
-                while (true) {
-                    if (++__j == __last) {
-                        // [__i, __last) sorted
-                        return;
-                    }
-                    if (__comp(*__j, *__m)) {
-                        // not yet sorted, so sort
-                        break;
-                    }
-                    __m = __j;
-                }
-            }
-        }
-        // __nth_element on range containing __nth
-        if (__nth < __i)
-        {
-            // _VSTD::__nth_element<_Compare>(__first, __nth, __i, __comp);
-            __last = __i;
-        }
-        else
-        {
-            // _VSTD::__nth_element<_Compare>(__i+1, __nth, __last, __comp);
-            __first = ++__i;
-        }
-    }
-}
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    _VSTD::__nth_element<_Comp_ref>(__first, __nth, __last, __comp);
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last)
-{
-    _VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// sort
-
-template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    if (__libcpp_is_constant_evaluated()) {
-        _VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
-    } else {
-        _VSTD::__sort<_Comp_ref>(_VSTD::__unwrap_iter(__first), _VSTD::__unwrap_iter(__last), _Comp_ref(__comp));
-    }
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
-    _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-// includes
-
-template <class _Compare, class _InputIterator1, class _InputIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-__includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
-           _Compare __comp)
-{
-    for (; __first2 != __last2; ++__first1)
-    {
-        if (__first1 == __last1 || __comp(*__first2, *__first1))
-            return false;
-        if (!__comp(*__first1, *__first2))
-            ++__first2;
-    }
-    return true;
-}
-
-template <class _InputIterator1, class _InputIterator2, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
-         _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__includes<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2)
-{
-    return _VSTD::includes(__first1, __last1, __first2, __last2,
-                          __less<typename iterator_traits<_InputIterator1>::value_type,
-                                 typename iterator_traits<_InputIterator2>::value_type>());
-}
-
-// set_union
-
-template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
-__set_union(_InputIterator1 __first1, _InputIterator1 __last1,
-            _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    for (; __first1 != __last1; ++__result)
-    {
-        if (__first2 == __last2)
-            return _VSTD::copy(__first1, __last1, __result);
-        if (__comp(*__first2, *__first1))
-        {
-            *__result = *__first2;
-            ++__first2;
-        }
-        else
-        {
-            if (!__comp(*__first1, *__first2))
-                ++__first2;
-            *__result = *__first1;
-            ++__first1;
-        }
-    }
-    return _VSTD::copy(__first2, __last2, __result);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_union(_InputIterator1 __first1, _InputIterator1 __last1,
-          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__set_union<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_union(_InputIterator1 __first1, _InputIterator1 __last1,
-          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
-{
-    return _VSTD::set_union(__first1, __last1, __first2, __last2, __result,
-                          __less<typename iterator_traits<_InputIterator1>::value_type,
-                                 typename iterator_traits<_InputIterator2>::value_type>());
-}
-
-// set_intersection
-
-template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
-__set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
-                   _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    while (__first1 != __last1 && __first2 != __last2)
-    {
-        if (__comp(*__first1, *__first2))
-            ++__first1;
-        else
-        {
-            if (!__comp(*__first2, *__first1))
-            {
-                *__result = *__first1;
-                ++__result;
-                ++__first1;
-            }
-            ++__first2;
-        }
-    }
-    return __result;
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
-                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__set_intersection<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
-                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
-{
-    return _VSTD::set_intersection(__first1, __last1, __first2, __last2, __result,
-                                  __less<typename iterator_traits<_InputIterator1>::value_type,
-                                         typename iterator_traits<_InputIterator2>::value_type>());
-}
-
-// set_difference
-
-template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
-__set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
-                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    while (__first1 != __last1)
-    {
-        if (__first2 == __last2)
-            return _VSTD::copy(__first1, __last1, __result);
-        if (__comp(*__first1, *__first2))
-        {
-            *__result = *__first1;
-            ++__result;
-            ++__first1;
-        }
-        else
-        {
-            if (!__comp(*__first2, *__first1))
-                ++__first1;
-            ++__first2;
-        }
-    }
-    return __result;
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
-               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__set_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
-               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
-{
-    return _VSTD::set_difference(__first1, __last1, __first2, __last2, __result,
-                                __less<typename iterator_traits<_InputIterator1>::value_type,
-                                       typename iterator_traits<_InputIterator2>::value_type>());
-}
-
-// set_symmetric_difference
-
-template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
-__set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
-                           _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    while (__first1 != __last1)
-    {
-        if (__first2 == __last2)
-            return _VSTD::copy(__first1, __last1, __result);
-        if (__comp(*__first1, *__first2))
-        {
-            *__result = *__first1;
-            ++__result;
-            ++__first1;
-        }
-        else
-        {
-            if (__comp(*__first2, *__first1))
-            {
-                *__result = *__first2;
-                ++__result;
-            }
-            else
-                ++__first1;
-            ++__first2;
-        }
-    }
-    return _VSTD::copy(__first2, __last2, __result);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
-                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__set_symmetric_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_OutputIterator
-set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
-                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
-{
-    return _VSTD::set_symmetric_difference(__first1, __last1, __first2, __last2, __result,
-                                          __less<typename iterator_traits<_InputIterator1>::value_type,
-                                                 typename iterator_traits<_InputIterator2>::value_type>());
-}
-
-// lexicographical_compare
-
-template <class _Compare, class _InputIterator1, class _InputIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-__lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
-                          _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
-{
-    for (; __first2 != __last2; ++__first1, (void) ++__first2)
-    {
-        if (__first1 == __last1 || __comp(*__first1, *__first2))
-            return true;
-        if (__comp(*__first2, *__first1))
-            return false;
-    }
-    return false;
-}
-
-template <class _InputIterator1, class _InputIterator2, class _Compare>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
-                        _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__lexicographical_compare<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
-}
-
-template <class _InputIterator1, class _InputIterator2>
-_LIBCPP_NODISCARD_EXT inline
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
-                        _InputIterator2 __first2, _InputIterator2 __last2)
-{
-    return _VSTD::lexicographical_compare(__first1, __last1, __first2, __last2,
-                                         __less<typename iterator_traits<_InputIterator1>::value_type,
-                                                typename iterator_traits<_InputIterator2>::value_type>());
-}
-
-// next_permutation
-
-template <class _Compare, class _BidirectionalIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-__next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
-{
-    _BidirectionalIterator __i = __last;
-    if (__first == __last || __first == --__i)
-        return false;
-    while (true)
-    {
-        _BidirectionalIterator __ip1 = __i;
-        if (__comp(*--__i, *__ip1))
-        {
-            _BidirectionalIterator __j = __last;
-            while (!__comp(*__i, *--__j))
-                ;
-            swap(*__i, *__j);
-            _VSTD::reverse(__ip1, __last);
-            return true;
-        }
-        if (__i == __first)
-        {
-            _VSTD::reverse(__first, __last);
-            return false;
-        }
-    }
-}
-
-template <class _BidirectionalIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__next_permutation<_Comp_ref>(__first, __last, __comp);
-}
-
-template <class _BidirectionalIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
-{
-    return _VSTD::next_permutation(__first, __last,
-                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
-}
-
-// prev_permutation
-
-template <class _Compare, class _BidirectionalIterator>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
-__prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
-{
-    _BidirectionalIterator __i = __last;
-    if (__first == __last || __first == --__i)
-        return false;
-    while (true)
-    {
-        _BidirectionalIterator __ip1 = __i;
-        if (__comp(*__ip1, *--__i))
-        {
-            _BidirectionalIterator __j = __last;
-            while (!__comp(*--__j, *__i))
-                ;
-            swap(*__i, *__j);
-            _VSTD::reverse(__ip1, __last);
-            return true;
-        }
-        if (__i == __first)
-        {
-            _VSTD::reverse(__first, __last);
-            return false;
-        }
-    }
-}
-
-template <class _BidirectionalIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
-{
-    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
-    return _VSTD::__prev_permutation<_Comp_ref>(__first, __last, __comp);
-}
-
-template <class _BidirectionalIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-bool
-prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
-{
-    return _VSTD::prev_permutation(__first, __last,
-                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
-}
-
-_LIBCPP_END_NAMESPACE_STD
-
 _LIBCPP_POP_MACROS
 
 #if defined(_LIBCPP_HAS_PARALLEL_ALGORITHMS) && _LIBCPP_STD_VER >= 17
 #   include <__pstl_algorithm>
 #endif
 
 #endif // _LIBCPP_ALGORITHM

libcxx/include/experimental/functional

inline namespace fundamentals_v1 {
 
   template<class R, class... ArgTypes, class Alloc>
   struct uses_allocator<experimental::function<R(ArgTypes...)>, Alloc>;
 
 } // namespace std
 
 */
 
+#include <__functional/search.h>
 #include <experimental/__config>
 #include <functional>
 #include <algorithm>
 #include <type_traits>
 #include <vector>
 #include <array>
 #include <unordered_map>
 

libcxx/include/functional

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.
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__functional_base>
+#include <__functional/search.h>
 #include <concepts>
 #include <exception>
 #include <memory>
 #include <tuple>
 #include <type_traits>
 #include <typeinfo>
 #include <utility>
 #include <version>
constexpr auto bind_front(_Fn&& __f, _Args&&... __args)
     return __perfect_forward<__bind_front_op, _Fn, _Args...>(_VSTD::forward<_Fn>(__f),
                                                              _VSTD::forward<_Args>(__args)...);
 }
 
 #endif // _LIBCPP_STD_VER > 17
 
 // struct hash<T*> in <memory>
 
-template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
-pair<_ForwardIterator1, _ForwardIterator1> _LIBCPP_CONSTEXPR_AFTER_CXX11
-__search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred,
-         forward_iterator_tag, forward_iterator_tag)
-{
-    if (__first2 == __last2)
-        return _VSTD::make_pair(__first1, __first1);  // Everything matches an empty sequence
-    while (true)
-    {
-        // Find first element in sequence 1 that matchs *__first2, with a mininum of loop checks
-        while (true)
-        {
-            if (__first1 == __last1)  // return __last1 if no element matches *__first2
-                return _VSTD::make_pair(__last1, __last1);
-            if (__pred(*__first1, *__first2))
-                break;
-            ++__first1;
-        }
-        // *__first1 matches *__first2, now match elements after here
-        _ForwardIterator1 __m1 = __first1;
-        _ForwardIterator2 __m2 = __first2;
-        while (true)
-        {
-            if (++__m2 == __last2)  // If pattern exhausted, __first1 is the answer (works for 1 element pattern)
-                return _VSTD::make_pair(__first1, __m1);
-            if (++__m1 == __last1)  // Otherwise if source exhaused, pattern not found
-                return _VSTD::make_pair(__last1, __last1);
-            if (!__pred(*__m1, *__m2))  // if there is a mismatch, restart with a new __first1
-            {
-                ++__first1;
-                break;
-            }  // else there is a match, check next elements
-        }
-    }
-}
-
-template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
-_LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<_RandomAccessIterator1, _RandomAccessIterator1>
-__search(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
-         _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
-           random_access_iterator_tag, random_access_iterator_tag)
-{
-    typedef typename iterator_traits<_RandomAccessIterator1>::difference_type _D1;
-    typedef typename iterator_traits<_RandomAccessIterator2>::difference_type _D2;
-    // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
-    const _D2 __len2 = __last2 - __first2;
-    if (__len2 == 0)
-        return _VSTD::make_pair(__first1, __first1);
-    const _D1 __len1 = __last1 - __first1;
-    if (__len1 < __len2)
-        return _VSTD::make_pair(__last1, __last1);
-    const _RandomAccessIterator1 __s = __last1 - (__len2 - 1);  // Start of pattern match can't go beyond here
-
-    while (true)
-    {
-        while (true)
-        {
-            if (__first1 == __s)
-                return _VSTD::make_pair(__last1, __last1);
-            if (__pred(*__first1, *__first2))
-                break;
-            ++__first1;
-        }
-
-        _RandomAccessIterator1 __m1 = __first1;
-        _RandomAccessIterator2 __m2 = __first2;
-         while (true)
-         {
-             if (++__m2 == __last2)
-                 return _VSTD::make_pair(__first1, __first1 + __len2);
-             ++__m1;          // no need to check range on __m1 because __s guarantees we have enough source
-             if (!__pred(*__m1, *__m2))
-             {
-                 ++__first1;
-                 break;
-             }
-         }
-    }
-}
-
 #if _LIBCPP_STD_VER > 14
 
 // default searcher
 template<class _ForwardIterator, class _BinaryPredicate = equal_to<>>
 class _LIBCPP_TEMPLATE_VIS default_searcher {
 public:
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     default_searcher(_ForwardIterator __f, _ForwardIterator __l,

libcxx/include/module.modulemap

module cwctype {
       export *
     }
   }
 
   module algorithm {
     header "algorithm"
     export initializer_list
     export *
+    module __algorithm {
+      module adjacent_find { header "__algorithm/adjacent_find.h" }
+      module all_of { header "__algorithm/all_of.h" }
+      module any_of { header "__algorithm/any_of.h" }
+      module binary_search { header "__algorithm/binary_search.h" }
+      module clamp { header "__algorithm/clamp.h" }
+      module comp { header "__algorithm/comp.h" }
+      module comp_ref_type { header "__algorithm/comp_ref_type.h" }
+      module copy { header "__algorithm/copy.h" }
+      module count { header "__algorithm/count.h" }
+      module count_if { header "__algorithm/count_if.h" }
+      module equal { header "__algorithm/equal.h" }
+      module equal_range { header "__algorithm/equal_range.h" }
+      module fill { header "__algorithm/fill.h" }
+      module find { header "__algorithm/find.h" }
+      module find_end { header "__algorithm/find_end.h" }
+      module find_first_of { header "__algorithm/find_first_of.h" }
+      module find_if { header "__algorithm/find_if.h" }
+      module find_if_not { header "__algorithm/find_if_not.h" }
+      module for_each { header "__algorithm/for_each.h" }
+      module for_each_n { header "__algorithm/for_each_n.h" }
+      module generate { header "__algorithm/generate.h" }
+      module half_positive { header "__algorithm/half_positive.h" }
+      module includes { header "__algorithm/includes.h" }
+      module inplace_merge { header "__algorithm/inplace_merge.h" }
+      module is_heap { header "__algorithm/is_heap.h" }
+      module is_heap_until { header "__algorithm/is_heap_until.h" }
+      module is_partitioned { header "__algorithm/is_partitioned.h" }
+      module is_permutation { header "__algorithm/is_permutation.h" }
+      module is_sorted { header "__algorithm/is_sorted.h" }
+      module lexicographical_compare { header "__algorithm/lexicographical_compare.h" }
+      module lower_bound { header "__algorithm/lower_bound.h" }
+      module make_heap { header "__algorithm/make_heap.h" }
+      module max { header "__algorithm/max.h" }
+      module max_element { header "__algorithm/max_element.h" }
+      module merge { header "__algorithm/merge.h" }
+      module min { header "__algorithm/min.h" }
+      module min_element { header "__algorithm/min_element.h" }
+      module minmax { header "__algorithm/minmax.h" }
+      module minmax_element { header "__algorithm/minmax_element.h" }
+      module mismatch { header "__algorithm/mismatch.h" }
+      module move { header "__algorithm/move.h" }
+      module next_permutation { header "__algorithm/next_permutation.h" }
+      module none_of { header "__algorithm/none_of.h" }
+      module nth_element { header "__algorithm/nth_element.h" }
+      module partial_sort { header "__algorithm/partial_sort.h" }
+      module partition { header "__algorithm/partition.h" }
+      module partition_point { header "__algorithm/partition_point.h" }
+      module pop_heap { header "__algorithm/pop_heap.h" }
+      module prev_permutation { header "__algorithm/prev_permutation.h" }
+      module push_heap { header "__algorithm/push_heap.h" }
+      module remove { header "__algorithm/remove.h" }
+      module replace { header "__algorithm/replace.h" }
+      module reverse { header "__algorithm/reverse.h" }
+      module rotate { header "__algorithm/rotate.h" }
+      module sample { header "__algorithm/sample.h" }
+      module search { header "__algorithm/search.h" }
+      module search_n { header "__algorithm/search_n.h" }
+      module set_difference { header "__algorithm/set_difference.h" }
+      module set_intersection { header "__algorithm/set_intersection.h" }
+      module set_symmetric_difference { header "__algorithm/set_symmetric_difference.h" }
+      module set_union { header "__algorithm/set_union.h" }
+      module shift { header "__algorithm/shift.h" }
+      module shuffle { header "__algorithm/shuffle.h" }
+      module sift_down { header "__algorithm/sift_down.h" }
+      module sort { header "__algorithm/sort.h" }
+      module sort_heap { header "__algorithm/sort_heap.h" }
+      module stable_partition { header "__algorithm/stable_partition.h" }
+      module stable_sort { header "__algorithm/stable_sort.h" }
+      module transform { header "__algorithm/transform.h" }
+      module uniform_int_distribution { header "__algorithm/uniform_int_distribution.h" }
+      module unique { header "__algorithm/unique.h" }
+      module unwrap_iter { header "__algorithm/unwrap_iter.h" }
+      module upper_bound { header "__algorithm/upper_bound.h" }
+
+      export *
+    }
   }
   module any {
     header "any"
     export *
   }
   module array {
     header "array"
     export initializer_list
module forward_list {
     export *
   }
   module fstream {
     header "fstream"
     export *
   }
   module functional {
     header "functional"
     export *
+    module __functional {
+      module search { header "__functional/search.h" }
+    }
   }
   module future {
     header "future"
     export *
   }
   module initializer_list {
     header "initializer_list"
     export *
module std [system] {
   module istream {
     header "istream"
     // FIXME: should re-export ios, streambuf?
     export *
   }
   module iterator {
     header "iterator"
     export *
-
     module __iterator {
       module advance              { header "__iterator/advance.h"              }
       module concepts             { header "__iterator/concepts.h"             }
       module default_sentinel     { header "__iterator/default_sentinel.h"     }
       module incrementable_traits { header "__iterator/incrementable_traits.h" }
       module indirect_concepts    { header "__iterator/indirect_concepts.h"    }
       module iter_move            { header "__iterator/iter_move.h"            }
       module iterator_traits      { header "__iterator/iterator_traits.h"      }
       module next                 { header "__iterator/next.h"                 }
       module prev                 { header "__iterator/prev.h"                 }
       module projected            { header "__iterator/projected.h"            }
       module readable_traits      { header "__iterator/readable_traits.h"      }
module std [system] {
   }
   module ranges {
     requires cplusplus20
     header "ranges"
     export compare
     export initializer_list
     export iterator
     export *
-
     module __ranges {
       module access                 { header "__ranges/access.h"                 }
       module concepts               { header "__ranges/concepts.h"               }
       module data                   { header "__ranges/data.h"                   }
       module empty                  { header "__ranges/empty.h"                  }
       module enabled_borrowed_range { header "__ranges/enabled_borrowed_range.h" }
       module size                   { header "__ranges/size.h"                   }
       module view_interface         { header "__ranges/view_interface.h"         }
       module view                   { header "__ranges/view.h"                   }
     }
   }
   module ratio {

libcxx/include/regex

 typedef regex_token_iterator<string::const_iterator>  sregex_token_iterator;
 typedef regex_token_iterator<wstring::const_iterator> wsregex_token_iterator;
 
 } // std
 */
 
 #include <__config>
 #include <__debug>
+#include <__functional/search.h>
 #include <__locale>
 #include <compare>
 #include <deque>
 #include <initializer_list>
 #include <iterator>
 #include <memory>
 #include <stdexcept>
 #include <string>

libcxx/test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.fail.cpp

template <class PopulationIterator, class SampleIterator> void test() {
   const unsigned os = 4;
   int oa[os];
   std::minstd_rand g;
   std::sample(PopulationIterator(ia), PopulationIterator(ia + is),
                             SampleIterator(oa), os, g);
 }
 
 int main(int, char**) {
-  // expected-error-re@algorithm:* {{static_assert failed{{( due to requirement '.*')?}} "SampleIterator must meet the requirements of RandomAccessIterator"}}
-  // expected-error@algorithm:* 2 {{does not provide a subscript operator}}
-  // expected-error@algorithm:* {{invalid operands}}
+  // expected-error-re@*:* {{static_assert failed{{( due to requirement '.*')?}} "SampleIterator must meet the requirements of RandomAccessIterator"}}
+  // expected-error@*:* 2 {{does not provide a subscript operator}}
+  // expected-error@*:* {{invalid operands}}
   test<cpp17_input_iterator<int *>, output_iterator<int *> >();
 
   return 0;
 }

libcxx/test/std/algorithms/alg.sorting/alg.min.max/requires_forward_iterator.fail.cpp

 
 #include "test_iterators.h"
 
 int main(int, char**) {
   int arr[] = {1, 2, 3};
   const int *b = std::begin(arr), *e = std::end(arr);
   typedef cpp17_input_iterator<const int*> Iter;
   {
-    // expected-error@algorithm:* {{"std::min_element requires a ForwardIterator"}}
+    // expected-error@*:* {{"std::min_element requires a ForwardIterator"}}
     std::min_element(Iter(b), Iter(e));
   }
   {
-    // expected-error@algorithm:* {{"std::max_element requires a ForwardIterator"}}
+    // expected-error@*:* {{"std::max_element requires a ForwardIterator"}}
     std::max_element(Iter(b), Iter(e));
   }
   {
-    // expected-error@algorithm:* {{"std::minmax_element requires a ForwardIterator"}}
+    // expected-error@*:* {{"std::minmax_element requires a ForwardIterator"}}
     std::minmax_element(Iter(b), Iter(e));
   }
 
 
   return 0;
 }

libcxx/test/std/containers/sequences/array/compare.fail.cpp

 template <int Dummy> struct NoCompare {};
 
 int main(int, char**)
 {
   {
     typedef NoCompare<0> T;
     typedef std::array<T, 3> C;
     C c1 = {{}};
-    // expected-error@algorithm:* 2 {{invalid operands to binary expression}}
+    // expected-error@*:* 2 {{invalid operands to binary expression}}
     TEST_IGNORE_NODISCARD (c1 == c1);
     TEST_IGNORE_NODISCARD (c1 < c1);
   }
   {
     typedef NoCompare<1> T;
     typedef std::array<T, 3> C;
     C c1 = {{}};
-    // expected-error@algorithm:* 2 {{invalid operands to binary expression}}
+    // expected-error@*:* 2 {{invalid operands to binary expression}}
     TEST_IGNORE_NODISCARD (c1 != c1);
     TEST_IGNORE_NODISCARD (c1 > c1);
   }
   {
     typedef NoCompare<2> T;
     typedef std::array<T, 0> C;
     C c1 = {{}};
-    // expected-error@algorithm:* 2 {{invalid operands to binary expression}}
+    // expected-error@*:* 2 {{invalid operands to binary expression}}
     TEST_IGNORE_NODISCARD (c1 == c1);
     TEST_IGNORE_NODISCARD (c1 < c1);
   }
 
   return 0;
 }