[libcxx][modularisation] moves <utility> content out of <type_traits>

[cjdb]

Summary

Moves:

• std::move, std::forward, std::declval, and std::swap into __utility/${FUNCTION_NAME}.
• std::swap_ranges and std::iter_swap into __algorithm/${FUNCTION_NAME}

[cjdb]

fixes circular dep

[Mordante]

I like this direction! I assume the patch has no changes in the moved code.
LGTM modulo one minor nit.

libcxx/include/type_traits

425

Can you add the reason for the removal in the comment?

[ldionne]

I'd like to better understand the motivation for this patch - are you working towards something specific? Generally LGTM.

libcxx/include/__decay_copy.h

1 ↗

(On Diff #350011)

Why is this at the top level?

libcxx/test/std/utilities/utility/utility.swap/swap_array.pass.cpp

17

This is using is_same, so it needs <type_traits>.

[cjdb]

transitively puts std::swap definition back into <type_traits> and adds a TODO so it can be removed in a future patch dedicated to header minimisation

[cjdb]

In D103734#2805384, @ldionne wrote:

I'd like to better understand the motivation for this patch - are you working towards something specific? Generally LGTM.

I'm breaking down <functional> into appropriate units so that __functional and friends can disappear (they don't play well with the module map and are really clunky to begin with).
<utility> needs to be broken down first, in order to achieve that.

So, I guess the final destination of this patch is to see <utility> and <functional> broken down. <type_traits> will likely get taken along for the ride too, but I have no (immediate) intention of looking at that header as a whole.

libcxx/include/__decay_copy.h

1 ↗

(On Diff #350011)

I didn't really know where to put it. It's in __type_traits now, but I should probably move it to __utility before merging.

[cjdb]

In D103734#2801111, @Mordante wrote:

I like this direction! I assume the patch has no changes in the moved code.
LGTM modulo one minor nit.

I made one minor change to swap, where I replaced the return type (which was obfuscated by ifdefs) with an alias so the compiler selection doesn't screw up readability.

It's still non-functional.

[ldionne]

<utility> needs to be broken down first, in order to achieve that.

Why? Can't you split <functional> without tackling down <utility>?

Note: Generally speaking, I'm very happy to split up headers into smaller headers that make sense (I've been fighting hard for that since the beginning). But I'm struggling to see the structure in this patch. It just looks to me as though random bits are being split into headers, and also I'm not sure about the granularity. In particular, splitting up type traits this way (one trait per header, but not always) does not appear like an improvement to me.

If you're trying to split up <functional>, is it possible to do it without touching other headers? If not, let's figure out a way forward. Also, do you really have to touch anything in <type_traits> except stuff that would clearly belong elsewhere (like iter_swap and swap_ranges, which are great examples of libc++'s failure to sanely split things with monolithic headers)?

[cjdb]

In D103734#2806363, @ldionne wrote:

<utility> needs to be broken down first, in order to achieve that.

Why? Can't you split <functional> without tackling down <utility>?

Sadly, no. Assuming I've properly split <functional>, I get a circular dep between the two. IIRC it's specifically std::pair that's causing me grief right now, but that depends on a fair bit in <utility>, so I decided that would be a better starting point.

Note: Generally speaking, I'm very happy to split up headers into smaller headers that make sense (I've been fighting hard for that since the beginning). But I'm struggling to see the structure in this patch. It just looks to me as though random bits are being split into headers, and also I'm not sure about the granularity. In particular, splitting up type traits this way (one trait per header, but not always) does not appear like an improvement to me.

I make no defence for how I've split <type_traits>. I'd prefer one trait per header, but I think you had other ideas and so I kind of went "we can properly fix this when someone has the time/courage to turn to <type_traits>".

If you're trying to split up <functional>, is it possible to do it without touching other headers? If not, let's figure out a way forward.

See above. And below. It's certainly not possible to avoid touching <utility>, because that's where unary_function currently lives.

Also, do you really have to touch anything in <type_traits> except stuff that would clearly belong elsewhere (like iter_swap and swap_ranges, which are great examples of libc++'s failure to sanely split things with monolithic headers)?

I've moved out the bare minimum of <type_traits> in this patch to facilitate the things I've put into self-contained headers. std::move, std::forward, and std::swap aren't supposed to be in <type_traits>, but the monolithic header model kinda forced us to do it this way.

[ldionne]

Recording offline discussion with Chris about how to move this forward:

1. Use static_cast<T&&> instead of std::forward in <type_traits> (this should only impact the implementation of __invoke)
2. Forward declare std::swap in <type_traits> just to implement the is_XXX_swappable_with traits

Now, <type_traits> should not depend on <utility> anymore (to validate). So then:

3. Move things that should be in <utility> but that are defined in <type_traits> out of <type_traits>

This should allow us to not move anything that belongs into <type_traits> (according to the standard) outside of <type_traits>.

[• Quuxplusone]

@ldionne wrote:

Recording offline discussion with Chris about how to move this forward:

Use static_cast<T&&> instead of std::forward in <type_traits> (this should only impact the implementation of __invoke)

Yes please.

Forward declare std::swap in <type_traits> just to implement the is_XXX_swappable_with traits

This likely won't work; but also, the historical libc++ approach here is to define all of the swap, iter_swap, swap_ranges algorithms directly in <type_traits> — they operate as a cohesive unit, so it makes sense to keep them together; and they are fundamental to a lot of libc++, so it makes sense to keep them in the "root-of-the-graph" header <type_traits> rather than trying to lift them up into some less fundamental header like <utility>. I strongly recommend keeping these three fundamental swap-related algorithms together. If you want to pull them out into something like __utility/swap.h or __type_traits/swap.h, that seems fine; but I would not recommend attempting to split swap apart from swap_ranges or even iter_swap.

great examples of libc++'s failure to sanely split things with monolithic headers

I would say, great examples of WG21's failure to understand cyclic dependencies. libc++ is doing the best it can. :)

[cjdb]

• reverts moving type traits out of <type_traits>
• removes all traces of <utility> from <type_traits>

[cjdb]

rebases to get new <algorithm> split

[ldionne]

libcxx/include/__utility/swap.h

34

Could you make this change as a separate NFC commit? I really want those modularization changes to contain no change whatsoever to the code itself. By the way, did you make any other change to the code except the std::forward => static_cast<T&&> transformation?

libcxx/include/type_traits

3869

I'd like to make this change as a separate NFC change, for the reason stated above.

libcxx/test/support/poisoned_hash_helper.h

12

We should never be including implementation detail headers from the test suite. If we can't include <utility> right now, we should do the pre-requisite task before landing this patch.

[ldionne]

libcxx/test/support/poisoned_hash_helper.h

12

Nevermind this comment, I just saw https://reviews.llvm.org/D104002.

[cjdb]

splits NFC changes out

[ldionne]

LGTM w/ comment.

libcxx/include/__algorithm/swap_ranges.h

28

This forward declaration isn't using the __swap_result_t you factored out. I think you should include __utility/swap.h here.

[• Quuxplusone]

libcxx/include/__algorithm/swap_ranges.h

28

Since std::swap is implemented in terms of std::swap_ranges, which itself is implemented in terms of std::swap, I think both of them should go into the same helper header. In main right now, that header is <type_traits>. I don't object to the idea of pulling them out into a single helper header, e.g. __utility/swap.h; but they ought to stay together, because cyclic dependency.

[cjdb]

rebases to fix modules CI

libcxx/include/CMakeLists.txt

set(files
   __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/is_sorted_until.h
+  __algorithm/iter_swap.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
set(files
   __algorithm/shift_left.h
   __algorithm/shift_right.h
   __algorithm/shuffle.h
   __algorithm/sift_down.h
   __algorithm/sort.h
   __algorithm/sort_heap.h
   __algorithm/stable_partition.h
   __algorithm/stable_sort.h
+  __algorithm/swap_ranges.h
   __algorithm/transform.h
   __algorithm/unique_copy.h
   __algorithm/unique.h
   __algorithm/unwrap_iter.h
   __algorithm/upper_bound.h
   __availability
   __bit_reference
   __bits
set(files
   __ranges/subrange.h
   __split_buffer
   __std_stream
   __string
   __threading_support
   __tree
   __tuple
   __undef_macros
+  __utility/__decay_copy.h
+  __utility/declval.h
+  __utility/forward.h
+  __utility/move.h
+  __utility/swap.h
   __utility/to_underlying.h
   algorithm
   any
   array
   atomic
   barrier
   bit
   bitset

libcxx/include/__algorithm/inplace_merge.h

 #include <__config>
 #include <__algorithm/comp.h>
 #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 <__utility/swap.h>
 #include <memory>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/include/__algorithm/iter_swap.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_ITER_SWAP_H
+#define _LIBCPP___ALGORITHM_ITER_SWAP_H
+
+#include <__config>
+#include <__utility/declval.h>
+#include <__utility/swap.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>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 void iter_swap(_ForwardIterator1 __a,
+                                                                              _ForwardIterator2 __b)
+    //                                  _NOEXCEPT_(_NOEXCEPT_(swap(*__a, *__b)))
+    _NOEXCEPT_(_NOEXCEPT_(swap(*declval<_ForwardIterator1>(), *declval<_ForwardIterator2>()))) {
+  swap(*__a, *__b);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_ITER_SWAP_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 <__utility/move.h>
 #include <cstring>
 #include <utility>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 

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.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/reverse.h>
 #include <__iterator/iterator_traits.h>
-#include <type_traits> // swap
+#include <__utility/swap.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/sort.h>
 #include <__iterator/iterator_traits.h>
-#include <type_traits> // swap
+#include <__utility/swap.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

libcxx/include/__algorithm/partial_sort.h

 
 #include <__config>
 #include <__algorithm/comp.h>
 #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>
-#include <type_traits> // swap
+#include <__utility/swap.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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 <__utility/swap.h>
+#include <utility> // pair
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

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.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/sift_down.h>
 #include <__iterator/iterator_traits.h>
-#include <type_traits> // swap
+#include <__utility/swap.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/reverse.h>
 #include <__iterator/iterator_traits.h>
-#include <type_traits> // swap
+#include <__utility/swap.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__iterator/iterator_traits.h>
-#include <type_traits> // swap
+#include <__utility/move.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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 <utility>
-#include <type_traits>
+#include <__algorithm/find_if.h>
+#include <__utility/move.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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 <__algorithm/iter_swap.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>
 

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 <__algorithm/move.h>
 #include <__algorithm/move_backward.h>
+#include <__algorithm/swap_ranges.h>
 #include <__config>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/next.h>
 #include <__iterator/prev.h>
-#include <type_traits>
+#include <__utility/swap.h>
+#include <iterator>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

libcxx/include/__algorithm/shift_right.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_RIGHT_H
 #define _LIBCPP___ALGORITHM_SHIFT_RIGHT_H
 
 #include <__config>
 #include <__algorithm/move.h>
 #include <__algorithm/move_backward.h>
+#include <__algorithm/swap_ranges.h>
 #include <__iterator/iterator_traits.h>
 #include <type_traits> // swap
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

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 <__iterator/iterator_traits.h>
 #include <__random/uniform_int_distribution.h>
+#include <__utility/swap.h>
 #include <cstddef>
 #include <cstdint>
-#include <type_traits> // swap
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

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 <utility>
-#include <type_traits>
+#include <__utility/move.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

libcxx/include/__algorithm/sort.h

 #define _LIBCPP___ALGORITHM_SORT_H
 
 #include <__config>
 #include <__algorithm/comp.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/min_element.h>
 #include <__algorithm/partial_sort.h>
 #include <__algorithm/unwrap_iter.h>
+#include <__utility/swap.h>
 #include <memory>
 #include <type_traits> // swap
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

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 <__utility/swap.h>
 #include <memory>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/include/__algorithm/stable_sort.h

 #define _LIBCPP___ALGORITHM_STABLE_SORT_H
 
 #include <__config>
 #include <__algorithm/comp.h>
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/inplace_merge.h>
 #include <__algorithm/sort.h>
 #include <__iterator/iterator_traits.h>
+#include <__utility/swap.h>
 #include <memory>
 #include <type_traits> // swap
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__algorithm/swap_ranges.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_SWAP_RANGES_H
+#define _LIBCPP___ALGORITHM_SWAP_RANGES_H
+
+#include <__config>
+#include <__utility/swap.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>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator2
+swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
+  for (; __first1 != __last1; ++__first1, (void)++__first2)
+    swap(*__first1, *__first2);
+  return __first2;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_SWAP_RANGES_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/comp.h>
 #include <__algorithm/adjacent_find.h>
 #include <__iterator/iterator_traits.h>
-#include <utility>
+#include <__utility/move.h>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/include/__iterator/concepts.h

 #define _LIBCPP___ITERATOR_CONCEPTS_H
 
 #include <__config>
 #include <__iterator/incrementable_traits.h>
 #include <__iterator/iter_move.h>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/readable_traits.h>
 #include <__memory/pointer_traits.h>
+#include <__utility/forward.h>
 #include <concepts>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__iterator/iter_move.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___ITERATOR_ITER_MOVE_H
 #define _LIBCPP___ITERATOR_ITER_MOVE_H
 
 #include <__config>
 #include <__iterator/iterator_traits.h>
+#include <__utility/forward.h>
 #include <concepts> // __class_or_enum
 #include <type_traits>
 #include <utility>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 

libcxx/include/__memory/allocator.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___MEMORY_ALLOCATOR_H
 #define _LIBCPP___MEMORY_ALLOCATOR_H
 
 #include <__config>
 #include <__memory/allocator_traits.h>
+#include <__utility/forward.h>
 #include <cstddef>
 #include <new>
 #include <stdexcept>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif

libcxx/include/__memory/allocator_traits.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___MEMORY_ALLOCATOR_TRAITS_H
 #define _LIBCPP___MEMORY_ALLOCATOR_TRAITS_H
 
 #include <__config>
 #include <__memory/construct_at.h>
 #include <__memory/pointer_traits.h>
+#include <__utility/forward.h>
 #include <limits>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__memory/compressed_pair.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___MEMORY_COMPRESSED_PAIR_H
 #define _LIBCPP___MEMORY_COMPRESSED_PAIR_H
 
 #include <__config>
+#include <__utility/forward.h>
 #include <tuple> // needed in c++03 for some constructors
 #include <type_traits>
 #include <utility>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 

libcxx/include/__memory/construct_at.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___MEMORY_CONSTRUCT_AT_H
 #define _LIBCPP___MEMORY_CONSTRUCT_AT_H
 
 #include <__config>
 #include <__debug>
+#include <__utility/forward.h>
 #include <utility>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/include/__memory/shared_ptr.h

 #include <__functional_base> // std::less, std::binary_function
 #include <__memory/addressof.h>
 #include <__memory/allocation_guard.h>
 #include <__memory/allocator.h>
 #include <__memory/allocator_traits.h>
 #include <__memory/compressed_pair.h>
 #include <__memory/pointer_traits.h>
 #include <__memory/unique_ptr.h>
+#include <__utility/forward.h>
 #include <cstddef>
 #include <cstdlib> // abort
 #include <iosfwd>
 #include <stdexcept>
 #include <type_traits>
 #include <utility>
 #if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 #  include <atomic>

libcxx/include/__memory/unique_ptr.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___MEMORY_UNIQUE_PTR_H
 #define _LIBCPP___MEMORY_UNIQUE_PTR_H
 
 #include <__config>
 #include <__functional_base> // std::less
 #include <__memory/allocator_traits.h> // __pointer
 #include <__memory/compressed_pair.h>
+#include <__utility/forward.h>
 #include <cstddef>
 #include <type_traits>
 #include <utility>
 
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 #   include <__memory/auto_ptr.h>
 #endif
 

libcxx/include/__ranges/access.h

 // -*- C++ -*-
 //===------------------------ __ranges/access.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___RANGES_ACCESS_H
 #define _LIBCPP___RANGES_ACCESS_H
 
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/readable_traits.h>
 #include <__ranges/enable_borrowed_range.h>
+#include <__utility/__decay_copy.h>
+#include <__utility/forward.h>
 #include <concepts>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__ranges/all.h

 
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__ranges/access.h>
 #include <__ranges/concepts.h>
 #include <__ranges/ref_view.h>
 #include <__ranges/subrange.h>
+#include <__utility/__decay_copy.h>
+#include <__utility/forward.h>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/include/__ranges/data.h

 // -*- C++ -*-
 //===------------------------ __ranges/data.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___RANGES_DATA_H
 #define _LIBCPP___RANGES_DATA_H
 
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__memory/pointer_traits.h>
 #include <__ranges/access.h>
+#include <__utility/forward.h>
 #include <concepts>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__ranges/empty.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___RANGES_EMPTY_H
 #define _LIBCPP___RANGES_EMPTY_H
 
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__ranges/access.h>
 #include <__ranges/size.h>
+#include <__utility/forward.h>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

libcxx/include/__ranges/size.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___RANGES_SIZE_H
 #define _LIBCPP___RANGES_SIZE_H
 
 #include <__config>
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__ranges/access.h>
+#include <__utility/__decay_copy.h>
+#include <__utility/forward.h>
 #include <concepts>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__split_buffer

 // -*- C++ -*-
 #ifndef _LIBCPP_SPLIT_BUFFER
 #define _LIBCPP_SPLIT_BUFFER
 
 #include <__config>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/__tree

 // -*- 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___TREE
 #define _LIBCPP___TREE
 
 #include <__config>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <iterator>
 #include <memory>
 #include <stdexcept>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif

libcxx/include/__utility/__decay_copy.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___TYPE_TRAITS_DECAY_COPY_H
+#define _LIBCPP___TYPE_TRAITS_DECAY_COPY_H
+
+#include <__config>
+#include <__utility/forward.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 _Tp>
+inline _LIBCPP_INLINE_VISIBILITY typename decay<_Tp>::type __decay_copy(_Tp&& __t)
+#if _LIBCPP_STD_VER > 17
+    noexcept(is_nothrow_convertible_v<_Tp, remove_reference_t<_Tp> >)
+#endif
+{
+  return _VSTD::forward<_Tp>(__t);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___TYPE_TRAITS_DECAY_COPY_H

libcxx/include/__utility/declval.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___UTILITY_DECLVAL_H
+#define _LIBCPP___UTILITY_DECLVAL_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
+
+// Suppress deprecation notice for volatile-qualified return type resulting
+// from volatile-qualified types _Tp.
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
+template <class _Tp>
+_Tp&& __declval(int);
+template <class _Tp>
+_Tp __declval(long);
+_LIBCPP_SUPPRESS_DEPRECATED_POP
+
+template <class _Tp>
+decltype(__declval<_Tp>(0)) declval() _NOEXCEPT;
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___UTILITY_DECLVAL_H

libcxx/include/__utility/forward.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___UTILITY_FORWARD_H
+#define _LIBCPP___UTILITY_FORWARD_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 _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR _Tp&&
+forward(typename remove_reference<_Tp>::type& __t) _NOEXCEPT {
+  return static_cast<_Tp&&>(__t);
+}
+
+template <class _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR _Tp&&
+forward(typename remove_reference<_Tp>::type&& __t) _NOEXCEPT {
+  static_assert(!is_lvalue_reference<_Tp>::value, "cannot forward an rvalue as an lvalue");
+  return static_cast<_Tp&&>(__t);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___UTILITY_FORWARD_H

libcxx/include/__utility/move.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___UTILITY_MOVE_H
+#define _LIBCPP___UTILITY_MOVE_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 _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename remove_reference<_Tp>::type&&
+move(_Tp&& __t) _NOEXCEPT {
+  typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type _Up;
+  return static_cast<_Up&&>(__t);
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+template <class _Tp>
+using __move_if_noexcept_result_t =
+    typename conditional<!is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value, const _Tp&,
+                         _Tp&&>::type;
+#else // _LIBCPP_CXX03_LANG
+template <class _Tp>
+using __move_if_noexcept_result_t = const _Tp&;
+#endif
+
+template <class _Tp>
+_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 __move_if_noexcept_result_t<_Tp>
+move_if_noexcept(_Tp& __x) _NOEXCEPT {
+  return _VSTD::move(__x);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___UTILITY_MOVE_H

libcxx/include/__utility/swap.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___UTILITY_SWAP_H
+#define _LIBCPP___UTILITY_SWAP_H
+
+#include <__config>
+#include <__utility/declval.h>
+#include <__utility/move.h>
+#include <type_traits>
+#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
+
+#ifndef _LIBCPP_CXX03_LANG
+template <class _Tp>
+using __swap_result_t = typename enable_if<is_move_constructible<_Tp>::value && is_move_assignable<_Tp>::value>::type;
+#else
+template <class>
+using __swap_result_t = void;
+#endif
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY __swap_result_t<_Tp> _LIBCPP_CONSTEXPR_AFTER_CXX17 swap(_Tp& __x, _Tp& __y)
+    _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value&& is_nothrow_move_assignable<_Tp>::value) {
+  _Tp __t(_VSTD::move(__x));
+  __x = _VSTD::move(__y);
+  __y = _VSTD::move(__t);
+}
+
+template <class _Tp, size_t _Np>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 typename enable_if<__is_swappable<_Tp>::value>::type
+swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value) {
+  for (size_t __i = 0; __i != _Np; ++__i) {
+    swap(__a[__i], __b[__i]);
+  }
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___UTILITY_SWAP_H

libcxx/include/algorithm

 #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/is_sorted_until.h>
+#include <__algorithm/iter_swap.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/shift_left.h>
 #include <__algorithm/shift_right.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/swap_ranges.h>
 #include <__algorithm/transform.h>
 #include <__algorithm/unique_copy.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

libcxx/include/any

template<class ValueType>
     ValueType* any_cast(any* operand) noexcept;
 
 } // namespace std
 
 */
 
 #include <__availability>
 #include <__config>
+#include <__utility/forward.h>
 #include <cstdlib>
 #include <memory>
 #include <type_traits>
 #include <typeinfo>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header

libcxx/include/deque

 
 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__split_buffer>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <compare>
 #include <initializer_list>
 #include <iterator>
 #include <stdexcept>
 #include <type_traits>
 #include <version>
 

libcxx/include/exception

 template <class _Tp, class _Up, bool>
 struct __throw_with_nested;
 
 template <class _Tp, class _Up>
 struct __throw_with_nested<_Tp, _Up, true> {
     _LIBCPP_NORETURN static inline _LIBCPP_INLINE_VISIBILITY void
     __do_throw(_Tp&& __t)
     {
-        throw __nested<_Up>(_VSTD::forward<_Tp>(__t));
+        throw __nested<_Up>(static_cast<_Tp&&>(__t));
     }
 };
 
 template <class _Tp, class _Up>
 struct __throw_with_nested<_Tp, _Up, false> {
     _LIBCPP_NORETURN static inline _LIBCPP_INLINE_VISIBILITY void
 #ifndef _LIBCPP_CXX03_LANG
     __do_throw(_Tp&& __t)
 #else
     __do_throw (_Tp& __t)
 #endif // _LIBCPP_CXX03_LANG
     {
-        throw _VSTD::forward<_Tp>(__t);
+        throw static_cast<_Tp&&>(__t);
     }
 };
 #endif
 
 template <class _Tp>
 _LIBCPP_NORETURN
 void
 throw_with_nested(_Tp&& __t)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
     typedef typename decay<_Tp>::type _Up;
     static_assert( is_copy_constructible<_Up>::value, "type thrown must be CopyConstructible");
     __throw_with_nested<_Tp, _Up,
         is_class<_Up>::value &&
         !is_base_of<nested_exception, _Up>::value &&
         !__libcpp_is_final<_Up>::value>::
-            __do_throw(_VSTD::forward<_Tp>(__t));
+            __do_throw(static_cast<_Tp&&>(__t));
 #else
     ((void)__t);
     // FIXME: Make this abort
 #endif
 }
 
 template <class _From, class _To>
 struct __can_dynamic_cast : public _LIBCPP_BOOL_CONSTANT(

libcxx/include/experimental/iterator

 } // namespace std
 
 */
 
 #include <experimental/__config>
 
 #if _LIBCPP_STD_VER > 11
 
+#include <__memory/addressof.h>
+#include <__utility/move.h>
+#include <__utility/forward.h>
 #include <iterator>
 
 _LIBCPP_BEGIN_NAMESPACE_LFTS
 
 template <class _Delim, class _CharT = char, class _Traits = char_traits<_CharT>>
 class ostream_joiner {
 public:
 

libcxx/include/filesystem

 
 } }  // namespaces std::filesystem
 
 */
 
 #include <__availability>
 #include <__config>
 #include <__debug>
+#include <__utility/forward.h>
 #include <chrono>
 #include <compare>
 #include <cstddef>
 #include <cstdlib>
 #include <iosfwd>
 #include <iterator>
 #include <memory>
 #include <stack>

libcxx/include/forward_list

template <class T, class Allocator, class Predicate>
     typename forward_list<T, Allocator>::size_type
     erase_if(forward_list<T, Allocator>& c, Predicate pred);    // C++20
 
 }  // std
 
 */
 
 #include <__config>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <initializer_list>
 #include <iterator>
 #include <limits>
 #include <memory>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

libcxx/include/functional

POLICY:  For non-variadic implementations, the number of arguments is limited
          will be minimal.
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__functional_base>
 #include <__functional/search.h>
+#include <__utility/forward.h>
 #include <concepts>
 #include <exception>
 #include <memory>
 #include <tuple>
 #include <type_traits>
 #include <typeinfo>
 #include <utility>
 #include <version>

libcxx/include/future

 
 }  // std
 
 */
 
 #include <__availability>
 #include <__config>
 #include <__debug>
+#include <__utility/__decay_copy.h>
+#include <__utility/forward.h>
 #include <chrono>
 #include <exception>
 #include <memory>
 #include <mutex>
 #include <system_error>
 #include <thread>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

libcxx/include/istream

 template <class Stream, class T>
   Stream&& operator>>(Stream&& is, T&& x);
 
 }  // std
 
 */
 
 #include <__config>
+#include <__utility/forward.h>
 #include <ostream>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS

libcxx/include/iterator

 #include <__iterator/iter_swap.h>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/next.h>
 #include <__iterator/prev.h>
 #include <__iterator/projected.h>
 #include <__iterator/readable_traits.h>
 #include <__memory/addressof.h>
 #include <__memory/pointer_traits.h>
+#include <__utility/forward.h>
 #include <compare>
 #include <concepts> // Mandated by the Standard.
 #include <cstddef>
 #include <initializer_list>
 #include <iosfwd> // for forward declarations of vector and string
 #include <type_traits>
 #include <version>
 

libcxx/include/list

template <class T, class Allocator, class Predicate>
     erase_if(list<T, Allocator>& c, Predicate pred);    // C++20
 
 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <initializer_list>
 #include <iterator>
 #include <limits>
 #include <memory>
 #include <type_traits>
 #include <version>
 

libcxx/include/map

 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__node_handle>
 #include <__tree>
+#include <__utility/forward.h>
 #include <compare>
 #include <functional>
 #include <initializer_list>
 #include <iterator> // __libcpp_erase_if_container
 #include <memory>
 #include <type_traits>
 #include <utility>
 #include <version>

libcxx/include/module.modulemap

module unordered_set {
     export *
   }
   module utility {
     header "utility"
     export initializer_list
     export *
 
     module __utility {
-      module to_underlying {
-        header "__utility/to_underlying.h"
-      }
+      module __decay_copy  { header "__utility/__decay_copy.h"  }
+      module declval       { header "__utility/declval.h"       }
+      module forward       { header "__utility/forward.h"       }
+      module move          { header "__utility/move.h"          }
+      module swap          { header "__utility/swap.h"          }
+      module to_underlying { header "__utility/to_underlying.h" }
     }
   }
   module valarray {
     header "valarray"
     export initializer_list
     export *
   }
   module variant {

libcxx/include/mutex

 
 }  // std
 
 */
 
 #include <__config>
 #include <__mutex_base>
 #include <__threading_support>
+#include <__utility/forward.h>
 #include <cstdint>
 #include <functional>
 #include <memory>
 #ifndef _LIBCPP_CXX03_LANG
 # include <tuple>
 #endif
 #include <version>
 

libcxx/include/queue

void swap(priority_queue<T, Container, Compare>& x,
             priority_queue<T, Container, Compare>& y)
             noexcept(noexcept(x.swap(y)));
 
 }  // std
 
 */
 
 #include <__config>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <compare>
 #include <deque>
 #include <functional>
 #include <vector>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header

libcxx/include/scoped_allocator

template <class OuterA1, class OuterA2, class... InnerAllocs>
     operator!=(const scoped_allocator_adaptor<OuterA1, InnerAllocs...>& a,
                const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& b) noexcept;
 
 }  // std
 
 */
 
 #include <__config>
+#include <__utility/forward.h>
 #include <memory>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD

libcxx/include/set

 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__node_handle>
 #include <__tree>
+#include <__utility/forward.h>
 #include <compare>
 #include <functional>
 #include <initializer_list>
 #include <iterator> // __libcpp_erase_if_container
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header

libcxx/include/stack

template <class T, class Container>
   void swap(stack<T, Container>& x, stack<T, Container>& y)
   noexcept(noexcept(x.swap(y)));
 
 }  // std
 
 */
 
 #include <__config>
+#include <__utility/forward.h>
 #include <deque>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 

libcxx/include/thread

 
 */
 
 #include <__config>
 #include <__debug>
 #include <__functional_base>
 #include <__mutex_base>
 #include <__threading_support>
+#include <__utility/__decay_copy.h>
+#include <__utility/forward.h>
 #include <chrono>
 #include <cstddef>
 #include <functional>
 #include <iosfwd>
 #include <memory>
 #include <system_error>
 #include <tuple>
 #include <type_traits>

libcxx/include/tuple

template <class... Types>
   swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
 
 }  // std
 
 */
 
 #include <__config>
 #include <__functional_base>
+#include <__utility/forward.h>
+#include <__utility/move.h>
 #include <__tuple>
 #include <compare>
 #include <cstddef>
 #include <type_traits>
 #include <utility>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

libcxx/include/type_traits

 
 */
 #include <__config>
 #include <cstddef>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS pair;
 template <class _Tp> class _LIBCPP_TEMPLATE_VIS reference_wrapper;
 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
 
 template <class _Tp, _Tp __v>

 #if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
 template <class _Tp>
 _LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_destructible_v
     = is_destructible<_Tp>::value;
 #endif
 
 #endif // __has_keyword(__is_destructible)
 
-// move
-
-template <class _Tp>
-_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-typename remove_reference<_Tp>::type&&
-move(_Tp&& __t) _NOEXCEPT
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type _Up;
-    return static_cast<_Up&&>(__t);
-}
-
-template <class _Tp>
-_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-_Tp&&
-forward(typename remove_reference<_Tp>::type& __t) _NOEXCEPT
-{
-    return static_cast<_Tp&&>(__t);
-}
-
-template <class _Tp>
-_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-_Tp&&
-forward(typename remove_reference<_Tp>::type&& __t) _NOEXCEPT
-{
-    static_assert(!is_lvalue_reference<_Tp>::value,
-                  "cannot forward an rvalue as an lvalue");
-    return static_cast<_Tp&&>(__t);
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-typename decay<_Tp>::type
-__decay_copy(_Tp&& __t)
-#if _LIBCPP_STD_VER > 17
-noexcept(is_nothrow_convertible_v<_Tp, remove_reference_t<_Tp>>)
-#endif
-{
-    return static_cast<_Tp&&>(__t);
-}
-
 template <class _MP, bool _IsMemberFunctionPtr, bool _IsMemberObjectPtr>
 struct __member_pointer_traits_imp
 {
 };
 
 template <class _Rp, class _Class, class ..._Param>
 struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...), true, false>
 {

 
 // bullets 1, 2 and 3
 
 template <class _Fp, class _A0, class ..._Args,
           class = __enable_if_bullet1<_Fp, _A0>>
 inline _LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR_AFTER_CXX17 auto
 __invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
 _LIBCPP_INVOKE_RETURN((static_cast<_A0&&>(__a0).*__f)(static_cast<_Args&&>(__args)...))
 
 template <class _Fp, class _A0, class ..._Args,
           class = __enable_if_bullet1<_Fp, _A0>>
 inline _LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR auto
 __invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
 _LIBCPP_INVOKE_RETURN((static_cast<_A0&&>(__a0).*__f)(static_cast<_Args&&>(__args)...))
 
_LIBCPP_INLINE_VAR constexpr bool is_nothrow_invocable_v
     = is_nothrow_invocable<_Fn, _Args...>::value;
 
 template <class _Ret, class _Fn, class ..._Args>
 _LIBCPP_INLINE_VAR constexpr bool is_nothrow_invocable_r_v
     = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
 
 #endif // _LIBCPP_STD_VER > 14
 
+// __swappable
+
 template <class _Tp> struct __is_swappable;
 template <class _Tp> struct __is_nothrow_swappable;
 
-// swap, swap_ranges
 
 #ifndef _LIBCPP_CXX03_LANG
 template <class _Tp>
 using __swap_result_t = typename enable_if<is_move_constructible<_Tp>::value && is_move_assignable<_Tp>::value>::type;
 #else
 template <class>
 using __swap_result_t = void;
 #endif
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR_AFTER_CXX17 __swap_result_t<_Tp>
 swap(_Tp& __x, _Tp& __y) _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value &&
-                                    is_nothrow_move_assignable<_Tp>::value)
-{
-    _Tp __t(_VSTD::move(__x));
-    __x = _VSTD::move(__y);
-    __y = _VSTD::move(__t);
-}
+                                    is_nothrow_move_assignable<_Tp>::value);
 
 template<class _Tp, size_t _Np>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 typename enable_if<
     __is_swappable<_Tp>::value
 >::type
-swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value)
-{
-    for (size_t __i = 0; __i != _Np; ++__i) {
-        swap(__a[__i], __b[__i]);
-    }
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator2
-swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
-{
-    for(; __first1 != __last1; ++__first1, (void) ++__first2)
-        swap(*__first1, *__first2);
-    return __first2;
-}
-
-// iter_swap
-
-template <class _ForwardIterator1, class _ForwardIterator2>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
-    //                                  _NOEXCEPT_(_NOEXCEPT_(swap(*__a, *__b)))
-               _NOEXCEPT_(_NOEXCEPT_(swap(*declval<_ForwardIterator1>(),
-                                          *declval<_ForwardIterator2>())))
-{
-    swap(*__a, *__b);
-}
-
-// __swappable
+swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value);
 
 namespace __detail
 {
 // ALL generic swap overloads MUST already have a declaration available at this point.
 
 template <class _Tp, class _Up = _Tp,
           bool _NotVoid = !is_void<_Tp>::value && !is_void<_Up>::value>
 struct __swappable_with

libcxx/include/unordered_map

 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__hash_table>
 #include <__node_handle>
+#include <__utility/forward.h>
 #include <compare>
 #include <functional>
 #include <iterator> // __libcpp_erase_if_container
 #include <stdexcept>
 #include <tuple>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

libcxx/include/unordered_set

 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__hash_table>
 #include <__node_handle>
+#include <__utility/forward.h>
 #include <compare>
 #include <functional>
 #include <iterator> // __libcpp_erase_if_container
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif

libcxx/include/utility

 
 }  // std
 
 */
 
 #include <__config>
 #include <__debug>
 #include <__tuple>
+#include <__utility/declval.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+#include <__utility/swap.h>
 #include <__utility/to_underlying.h>
 #include <compare>
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <initializer_list>
 #include <limits>
 #include <type_traits>

 bool
 operator>=(const _Tp& __x, const _Tp& __y)
 {
     return !(__x < __y);
 }
 
 }  // rel_ops
 
-// swap_ranges is defined in <type_traits>`
-
-// swap is defined in <type_traits>
-
-// move_if_noexcept
-
-#ifndef _LIBCPP_CXX03_LANG
-template <class _Tp>
-using __move_if_noexcept_result_t =
-    typename conditional<!is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value, const _Tp&,
-                         _Tp&&>::type;
-#else // _LIBCPP_CXX03_LANG
-template <class _Tp>
-using __move_if_noexcept_result_t = const _Tp&;
-#endif
-
-template <class _Tp>
-_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-__move_if_noexcept_result_t<_Tp> move_if_noexcept(_Tp& __x) _NOEXCEPT
-{
-    return _VSTD::move(__x);
-}
-
 #if _LIBCPP_STD_VER > 14
 template <class _Tp>
 _LIBCPP_NODISCARD_EXT constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
 
 template <class _Tp>
 void as_const(const _Tp&&) = delete;
 #endif
 

libcxx/include/variant

namespace std {
   template <> struct hash<monostate>;
 
 } // namespace std
 
 */
 
 #include <__availability>
 #include <__config>
+#include <__utility/forward.h>
 #include <__tuple>
 #include <array>
 #include <compare>
 #include <exception>
 #include <functional>
 #include <initializer_list>
 #include <limits>
 #include <new>

libcxx/include/vector

 
 */
 
 #include <__config>
 #include <__bit_reference>
 #include <__debug>
 #include <__functional_base>
 #include <__split_buffer>
+#include <__utility/forward.h>
 #include <algorithm>
 #include <climits>
 #include <compare>
 #include <cstring>
 #include <initializer_list>
 #include <iosfwd> // for forward declaration of vector
 #include <limits>
 #include <memory>

libcxx/test/std/utilities/utility/forward/forward.fail.cpp

 
 A source() {return A();}
 const A csource() {return A();}
 
 int main(int, char**)
 {
     {
         std::forward<A&>(source());  // expected-note {{requested here}}
-        // expected-error-re@type_traits:* 1 {{static_assert failed{{.*}} "cannot forward an rvalue as an lvalue"}}
+        // expected-error-re@*:* 1 {{static_assert failed{{.*}} "cannot forward an rvalue as an lvalue"}}
     }
     {
         const A ca = A();
         std::forward<A&>(ca); // expected-error {{no matching function for call to 'forward'}}
     }
     {
         std::forward<A&>(csource());  // expected-error {{no matching function for call to 'forward'}}
     }

libcxx/test/std/utilities/utility/utility.swap/swap.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // <utility>
 
 // template<class T>
 //   requires MoveAssignable<T> && MoveConstructible<T>
 //   void
 //   swap(T& a, T& b);
 
-#include <utility>
 #include <cassert>
 #include <memory>
+#include <type_traits>
+#include <utility>
 
 #include "test_macros.h"
 
 #if TEST_STD_VER >= 11
 struct CopyOnly {
     CopyOnly() {}
     CopyOnly(CopyOnly const&) noexcept {}
     CopyOnly& operator=(CopyOnly const&) { return *this; }

libcxx/test/std/utilities/utility/utility.swap/swap_array.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // <utility>
 
 // template<ValueType T, size_t N>
 //   requires Swappable<T>
 //   void
 //   swap(T (&a)[N], T (&b)[N]);
 
-#include <utility>
+#include <algorithm>
 #include <cassert>
 #include <memory>
+#include <type_traits>
+#include <utility>
 
 #include "test_macros.h"
 
 
 #if TEST_STD_VER >= 11
 struct CopyOnly {
     CopyOnly() {}
     CopyOnly(CopyOnly const&) noexcept {}

libcxx/test/support/poisoned_hash_helper.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 SUPPORT_POISONED_HASH_HELPER_H
 #define SUPPORT_POISONED_HASH_HELPER_H
 
-#include <type_traits>
+#include <__utility/move.h> // TODO: replace with <utility> when std::hash is moved out of the header
 #include <cassert>
+#include <type_traits>
 
 #include "test_macros.h"
 #include "test_workarounds.h"
 
 #if TEST_STD_VER < 11
 #error this header may only be used in C++11 or newer
 #endif