[libc++] Split allocator_traits and pointer_traits out of <memory>

[ldionne]

Summary

In addition to making the code a lot easier to grasp by localizing many
helper functions to the only file where they are actually needed, this
will allow creating helper functions that depend on allocator_traits
outside of <memory>.

This is done as part of implementing array support in allocate_shared,
which requires non-trivial array initialization algorithms that would be
better to keep out of <memory> for sanity. It's also a first step towards
splitting up our monolithic headers into finer grained ones, which will
make it easier to reuse functionality across the library. For example,
it's just weird that we had to define addressof inside <type_traits>
to avoid circular dependencies -- instead it's better to implement those
in true helper headers.

[ldionne]

Fix test

[miscco]

I love hat you start breaking up the headers.

libcxx/include/__memory/allocator_traits.h

15

Should this also be __base.h to make clear that these are purely internal headers?

35

Maybe __pointer_type_impl ?

I have never seen imp as an abreviation. That said it is kind of fitting ;)

38

I _guess_ Dp stands for decayed type but I am not even sure

Could we give it a better name so that it is more obvious for new readers what it is?

libcxx/include/__memory/base.h

73

Missing comment here

[ldionne]

I agree with your comments, however this is a split only, I'm keeping the code 100% the same to avoid mixing concerns. I actually do have a patch coming up that refactors allocator_traits, where I'll make sure to apply your comments.

libcxx/include/__memory/allocator_traits.h

15

I've put the headers in a directory that had __ in it to make it clear it was internal (and to avoid conflicting with user-provided directories as much as possible). I don't think it's necessary to have the file contain __ too IMO.

[tschuett]

Does __memory/* gets its own entry in the module.modulemap?

[ldionne]

In D93074#2449448, @tschuett wrote:

Does __memory/* gets its own entry in the module.modulemap?

I don't think that's necessary since it's an implementation detail -- kinda like the __support/ headers are not mentioned in the modulemap. Do you agree?

[tschuett]

It is not necessary, but modules are faster to parse than headers.

-> I don't care.

Clang supports "private modules".
https://clang.llvm.org/docs/Modules.html#private-module-map-files

Somehow the private module doesn't work because module.modulemap contains two modules (std_config and std).

[ldionne]

In D93074#2449638, @tschuett wrote:

It is not necessary, but modules are faster to parse than headers.

-> I don't care.

Clang supports "private modules".
https://clang.llvm.org/docs/Modules.html#private-module-map-files

Somehow the private module doesn't work because module.modulemap contains two modules (std_config and std).

Hmm, I see. Ok, well thanks for trying anyway. I guess this is going in as-is then.

[ldionne]

Rebase onto master

[ldionne]

I'll ship this once CI passes.

[• Quuxplusone]

libcxx/include/__memory/allocator_traits.h

15

FWIW, I just saw this today, and I wish the level of directory structure weren't there; I'd rather have seen <__memory_base>, <__memory_pointer_traits>, <__memory_allocator_traits>. I don't even know what's in <__memory/utilities.h>, so I probably wouldn't have split it out — just combine it into <__memory_base> if it's needed by lots of things, and otherwise leave it in <memory>.

[• Quuxplusone]

libcxx/include/__memory/allocator_traits.h

15

Worse, I have just noticed that this moves addressof out of <type_traits> and into base.h, which depends on <type_traits>; so my <type_traits> can no longer use addressof to implement swap for trivially relocatable types. In my branch, I'm moving addressof back into <type_traits>.

I do have some vague ideas re a new <__type_traits_base>, to contain declval and forward and move and addressof and swap and the helpers like _EnableIf and whatever type-traits seem most used (e.g. is_*_constructible, is_integral, is_signed). But, I don't think that's really worth pursuing, because libc++'s current philosophy is "<type_traits> goes at the root"; there's no point in trying to make other headers not include <type_traits> because everyone is going to include <type_traits> at some point anyway.

I agree with trying to extract a <__memory_base>. Also, in C++20 we'll need an <__algorithm_base> to avoid dragging all the Ranges stuff into <vector> and <string>.

libcxx/include/CMakeLists.txt

 set(files
   __availability
   __bit_reference
   __bsd_locale_defaults.h
   __bsd_locale_fallbacks.h
   __debug
   __errc
   __functional_03
   __functional_base
   __functional_base_03
   __hash_table
   __libcpp_version
   __locale
+  __memory/allocator_traits.h
+  __memory/base.h
+  __memory/pointer_traits.h
   __mutex_base
   __node_handle
   __nullptr
   __split_buffer
   __sso_allocator
   __std_stream
   __string
   __threading_support

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/base.h>
+#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
+
+template <class _Tp, class = void>
+struct __has_pointer_type : false_type {};
+
+template <class _Tp>
+struct __has_pointer_type<_Tp,
+          typename __void_t<typename _Tp::pointer>::type> : true_type {};
+
+namespace __pointer_type_imp
+{
+
+template <class _Tp, class _Dp, bool = __has_pointer_type<_Dp>::value>
+struct __pointer_type
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Dp::pointer type;
+};
+
+template <class _Tp, class _Dp>
+struct __pointer_type<_Tp, _Dp, false>
+{
+    typedef _LIBCPP_NODEBUG_TYPE _Tp* type;
+};
+
+}  // __pointer_type_imp
+
+template <class _Tp, class _Dp>
+struct __pointer_type
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename __pointer_type_imp::__pointer_type<_Tp, typename remove_reference<_Dp>::type>::type type;
+};
+
+template <class _Tp, class = void>
+struct __has_const_pointer : false_type {};
+
+template <class _Tp>
+struct __has_const_pointer<_Tp,
+            typename __void_t<typename _Tp::const_pointer>::type> : true_type {};
+
+template <class _Tp, class _Ptr, class _Alloc, bool = __has_const_pointer<_Alloc>::value>
+struct __const_pointer
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::const_pointer type;
+};
+
+template <class _Tp, class _Ptr, class _Alloc>
+struct __const_pointer<_Tp, _Ptr, _Alloc, false>
+{
+#ifndef _LIBCPP_CXX03_LANG
+    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<const _Tp> type;
+#else
+    typedef typename pointer_traits<_Ptr>::template rebind<const _Tp>::other type;
+#endif
+};
+
+template <class _Tp, class = void>
+struct __has_void_pointer : false_type {};
+
+template <class _Tp>
+struct __has_void_pointer<_Tp,
+               typename __void_t<typename _Tp::void_pointer>::type> : true_type {};
+
+template <class _Ptr, class _Alloc, bool = __has_void_pointer<_Alloc>::value>
+struct __void_pointer
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::void_pointer type;
+};
+
+template <class _Ptr, class _Alloc>
+struct __void_pointer<_Ptr, _Alloc, false>
+{
+#ifndef _LIBCPP_CXX03_LANG
+    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<void> type;
+#else
+    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<void>::other type;
+#endif
+};
+
+template <class _Tp, class = void>
+struct __has_const_void_pointer : false_type {};
+
+template <class _Tp>
+struct __has_const_void_pointer<_Tp,
+            typename __void_t<typename _Tp::const_void_pointer>::type> : true_type {};
+
+template <class _Ptr, class _Alloc, bool = __has_const_void_pointer<_Alloc>::value>
+struct __const_void_pointer
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::const_void_pointer type;
+};
+
+template <class _Ptr, class _Alloc>
+struct __const_void_pointer<_Ptr, _Alloc, false>
+{
+#ifndef _LIBCPP_CXX03_LANG
+    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<const void> type;
+#else
+    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<const void>::other type;
+#endif
+};
+
+template <class _Tp, class = void>
+struct __has_size_type : false_type {};
+
+template <class _Tp>
+struct __has_size_type<_Tp,
+               typename __void_t<typename _Tp::size_type>::type> : true_type {};
+
+template <class _Alloc, class _DiffType, bool = __has_size_type<_Alloc>::value>
+struct __size_type
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename make_unsigned<_DiffType>::type type;
+};
+
+template <class _Alloc, class _DiffType>
+struct __size_type<_Alloc, _DiffType, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::size_type type;
+};
+
+template <class _Tp, class = void>
+struct __has_propagate_on_container_copy_assignment : false_type {};
+
+template <class _Tp>
+struct __has_propagate_on_container_copy_assignment<_Tp,
+    typename __void_t<typename _Tp::propagate_on_container_copy_assignment>::type>
+        : true_type {};
+
+template <class _Alloc, bool = __has_propagate_on_container_copy_assignment<_Alloc>::value>
+struct __propagate_on_container_copy_assignment
+{
+    typedef _LIBCPP_NODEBUG_TYPE false_type type;
+};
+
+template <class _Alloc>
+struct __propagate_on_container_copy_assignment<_Alloc, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::propagate_on_container_copy_assignment type;
+};
+
+template <class _Tp, class = void>
+struct __has_propagate_on_container_move_assignment : false_type {};
+
+template <class _Tp>
+struct __has_propagate_on_container_move_assignment<_Tp,
+           typename __void_t<typename _Tp::propagate_on_container_move_assignment>::type>
+               : true_type {};
+
+template <class _Alloc, bool = __has_propagate_on_container_move_assignment<_Alloc>::value>
+struct __propagate_on_container_move_assignment
+{
+    typedef false_type type;
+};
+
+template <class _Alloc>
+struct __propagate_on_container_move_assignment<_Alloc, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::propagate_on_container_move_assignment type;
+};
+
+template <class _Tp, class = void>
+struct __has_propagate_on_container_swap : false_type {};
+
+template <class _Tp>
+struct __has_propagate_on_container_swap<_Tp,
+           typename __void_t<typename _Tp::propagate_on_container_swap>::type>
+               : true_type {};
+
+template <class _Alloc, bool = __has_propagate_on_container_swap<_Alloc>::value>
+struct __propagate_on_container_swap
+{
+    typedef false_type type;
+};
+
+template <class _Alloc>
+struct __propagate_on_container_swap<_Alloc, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::propagate_on_container_swap type;
+};
+
+template <class _Tp, class = void>
+struct __has_is_always_equal : false_type {};
+
+template <class _Tp>
+struct __has_is_always_equal<_Tp,
+           typename __void_t<typename _Tp::is_always_equal>::type>
+               : true_type {};
+
+template <class _Alloc, bool = __has_is_always_equal<_Alloc>::value>
+struct __is_always_equal
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _VSTD::is_empty<_Alloc>::type type;
+};
+
+template <class _Alloc>
+struct __is_always_equal<_Alloc, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::is_always_equal type;
+};
+
+template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
+struct __has_rebind_other
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Xp> static __two __test(...);
+    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>::other* = 0);
+    _LIBCPP_SUPPRESS_DEPRECATED_POP
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Tp, class _Up>
+struct __has_rebind_other<_Tp, _Up, false>
+{
+    static const bool value = false;
+};
+
+template <class _Tp, class _Up, bool = __has_rebind_other<_Tp, _Up>::value>
+struct __allocator_traits_rebind
+{
+    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+    typedef _LIBCPP_NODEBUG_TYPE typename _Tp::template rebind<_Up>::other type;
+    _LIBCPP_SUPPRESS_DEPRECATED_POP
+};
+
+template <template <class, class...> class _Alloc, class _Tp, class ..._Args, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _Args...>, _Up, true>
+{
+    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc<_Tp, _Args...>::template rebind<_Up>::other type;
+    _LIBCPP_SUPPRESS_DEPRECATED_POP
+};
+
+template <template <class, class...> class _Alloc, class _Tp, class ..._Args, class _Up>
+struct __allocator_traits_rebind<_Alloc<_Tp, _Args...>, _Up, false>
+{
+    typedef _LIBCPP_NODEBUG_TYPE _Alloc<_Up, _Args...> type;
+};
+
+#ifndef _LIBCPP_CXX03_LANG
+
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+auto
+__has_allocate_hint_test(_Alloc&& __a, _SizeType&& __sz, _ConstVoidPtr&& __p)
+    -> decltype((void)__a.allocate(__sz, __p), true_type());
+_LIBCPP_SUPPRESS_DEPRECATED_POP
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+auto
+__has_allocate_hint_test(const _Alloc& __a, _SizeType&& __sz, _ConstVoidPtr&& __p)
+    -> false_type;
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+struct __has_allocate_hint
+    : decltype(_VSTD::__has_allocate_hint_test(declval<_Alloc>(),
+                                               declval<_SizeType>(),
+                                               declval<_ConstVoidPtr>()))
+{
+};
+
+#else  // _LIBCPP_CXX03_LANG
+
+template <class _Alloc, class _SizeType, class _ConstVoidPtr>
+struct __has_allocate_hint
+    : true_type
+{
+};
+
+#endif  // _LIBCPP_CXX03_LANG
+
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
+template <class _Alloc, class ..._Args,
+    class = decltype(_VSTD::declval<_Alloc>().construct(_VSTD::declval<_Args>()...))>
+static true_type __test_has_construct(int);
+_LIBCPP_SUPPRESS_DEPRECATED_POP
+
+template <class _Alloc, class...>
+static false_type __test_has_construct(...);
+
+template <class _Alloc, class ..._Args>
+struct __has_construct : decltype(__test_has_construct<_Alloc, _Args...>(0)) {};
+
+#if !defined(_LIBCPP_CXX03_LANG)
+
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
+template <class _Alloc, class _Pointer>
+auto
+__has_destroy_test(_Alloc&& __a, _Pointer&& __p)
+    -> decltype(__a.destroy(__p), true_type());
+_LIBCPP_SUPPRESS_DEPRECATED_POP
+
+template <class _Alloc, class _Pointer>
+auto
+__has_destroy_test(const _Alloc& __a, _Pointer&& __p)
+    -> false_type;
+
+template <class _Alloc, class _Pointer>
+struct __has_destroy
+    : decltype(_VSTD::__has_destroy_test(declval<_Alloc>(),
+                                         declval<_Pointer>()))
+{
+};
+
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
+template <class _Alloc>
+auto
+__has_max_size_test(_Alloc&& __a)
+    -> decltype(__a.max_size(), true_type());
+_LIBCPP_SUPPRESS_DEPRECATED_POP
+
+template <class _Alloc>
+auto
+__has_max_size_test(const volatile _Alloc& __a)
+    -> false_type;
+
+template <class _Alloc>
+struct __has_max_size
+    : decltype(_VSTD::__has_max_size_test(declval<_Alloc&>()))
+{
+};
+
+template <class _Alloc>
+auto
+__has_select_on_container_copy_construction_test(_Alloc&& __a)
+    -> decltype(__a.select_on_container_copy_construction(), true_type());
+
+template <class _Alloc>
+auto
+__has_select_on_container_copy_construction_test(const volatile _Alloc& __a)
+    -> false_type;
+
+template <class _Alloc>
+struct __has_select_on_container_copy_construction
+    : decltype(_VSTD::__has_select_on_container_copy_construction_test(declval<_Alloc&>()))
+{
+};
+
+#else  // _LIBCPP_CXX03_LANG
+
+template <class _Alloc, class _Pointer, class = void>
+struct __has_destroy : false_type {};
+
+template <class _Alloc, class _Pointer>
+struct __has_destroy<_Alloc, _Pointer, typename __void_t<
+    decltype(_VSTD::declval<_Alloc>().destroy(_VSTD::declval<_Pointer>()))
+>::type> : true_type {};
+
+template <class _Alloc>
+struct __has_max_size
+    : true_type
+{
+};
+
+template <class _Alloc>
+struct __has_select_on_container_copy_construction
+    : false_type
+{
+};
+
+#endif  // _LIBCPP_CXX03_LANG
+
+template <class _Alloc, class _Ptr, bool = __has_difference_type<_Alloc>::value>
+struct __alloc_traits_difference_type
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::difference_type type;
+};
+
+template <class _Alloc, class _Ptr>
+struct __alloc_traits_difference_type<_Alloc, _Ptr, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::difference_type type;
+};
+
+template <class _Tp>
+struct __is_default_allocator : false_type {};
+
+template <class _Tp>
+struct __is_default_allocator<_VSTD::allocator<_Tp> > : true_type {};
+
+
+
+template <class _Alloc,
+    bool = __has_construct<_Alloc, typename _Alloc::value_type*,  typename _Alloc::value_type&&>::value && !__is_default_allocator<_Alloc>::value
+    >
+struct __is_cpp17_move_insertable;
+template <class _Alloc>
+struct __is_cpp17_move_insertable<_Alloc, true> : true_type {};
+template <class _Alloc>
+struct __is_cpp17_move_insertable<_Alloc, false> : is_move_constructible<typename _Alloc::value_type> {};
+
+template <class _Alloc,
+    bool = __has_construct<_Alloc, typename _Alloc::value_type*, const typename _Alloc::value_type&>::value && !__is_default_allocator<_Alloc>::value
+    >
+struct __is_cpp17_copy_insertable;
+template <class _Alloc>
+struct __is_cpp17_copy_insertable<_Alloc, true> : __is_cpp17_move_insertable<_Alloc> {};
+template <class _Alloc>
+struct __is_cpp17_copy_insertable<_Alloc, false> : integral_constant<bool,
+    is_copy_constructible<typename _Alloc::value_type>::value &&
+    __is_cpp17_move_insertable<_Alloc>::value>
+  {};
+
+
+
+template <class _Alloc>
+struct _LIBCPP_TEMPLATE_VIS allocator_traits
+{
+    typedef _Alloc                              allocator_type;
+    typedef typename allocator_type::value_type value_type;
+
+    typedef typename __pointer_type<value_type, allocator_type>::type pointer;
+    typedef typename __const_pointer<value_type, pointer, allocator_type>::type const_pointer;
+    typedef typename __void_pointer<pointer, allocator_type>::type void_pointer;
+    typedef typename __const_void_pointer<pointer, allocator_type>::type const_void_pointer;
+
+    typedef typename __alloc_traits_difference_type<allocator_type, pointer>::type difference_type;
+    typedef typename __size_type<allocator_type, difference_type>::type size_type;
+
+    typedef typename __propagate_on_container_copy_assignment<allocator_type>::type
+                     propagate_on_container_copy_assignment;
+    typedef typename __propagate_on_container_move_assignment<allocator_type>::type
+                     propagate_on_container_move_assignment;
+    typedef typename __propagate_on_container_swap<allocator_type>::type
+                     propagate_on_container_swap;
+    typedef typename __is_always_equal<allocator_type>::type
+                     is_always_equal;
+
+#ifndef _LIBCPP_CXX03_LANG
+    template <class _Tp> using rebind_alloc =
+                  typename __allocator_traits_rebind<allocator_type, _Tp>::type;
+    template <class _Tp> using rebind_traits = allocator_traits<rebind_alloc<_Tp> >;
+#else  // _LIBCPP_CXX03_LANG
+    template <class _Tp> struct rebind_alloc
+        {typedef typename __allocator_traits_rebind<allocator_type, _Tp>::type other;};
+    template <class _Tp> struct rebind_traits
+        {typedef allocator_traits<typename rebind_alloc<_Tp>::other> other;};
+#endif  // _LIBCPP_CXX03_LANG
+
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static pointer allocate(allocator_type& __a, size_type __n)
+        {return __a.allocate(__n);}
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
+        {return __allocate(__a, __n, __hint,
+            __has_allocate_hint<allocator_type, size_type, const_void_pointer>());}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static void deallocate(allocator_type& __a, pointer __p, size_type __n) _NOEXCEPT
+        {__a.deallocate(__p, __n);}
+
+    template <class _Tp, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        static void construct(allocator_type& __a, _Tp* __p, _Args&&... __args)
+            {__construct(__has_construct<allocator_type, _Tp*, _Args...>(),
+                         __a, __p, _VSTD::forward<_Args>(__args)...);}
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        static void destroy(allocator_type& __a, _Tp* __p)
+            {__destroy(__has_destroy<allocator_type, _Tp*>(), __a, __p);}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static size_type max_size(const allocator_type& __a) _NOEXCEPT
+        {return __max_size(__has_max_size<const allocator_type>(), __a);}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static allocator_type
+        select_on_container_copy_construction(const allocator_type& __a)
+            {return __select_on_container_copy_construction(
+                __has_select_on_container_copy_construction<const allocator_type>(),
+                __a);}
+
+private:
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static pointer __allocate(allocator_type& __a, size_type __n,
+        const_void_pointer __hint, true_type)
+        {
+            _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+            return __a.allocate(__n, __hint);
+            _LIBCPP_SUPPRESS_DEPRECATED_POP
+        }
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static pointer __allocate(allocator_type& __a, size_type __n,
+        const_void_pointer, false_type)
+        {return __a.allocate(__n);}
+
+    template <class _Tp, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        static void __construct(true_type, allocator_type& __a, _Tp* __p, _Args&&... __args)
+            {
+                _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+                __a.construct(__p, _VSTD::forward<_Args>(__args)...);
+                _LIBCPP_SUPPRESS_DEPRECATED_POP
+            }
+
+    template <class _Tp, class... _Args>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        static void __construct(false_type, allocator_type&, _Tp* __p, _Args&&... __args)
+            {
+#if _LIBCPP_STD_VER > 17
+                _VSTD::construct_at(__p, _VSTD::forward<_Args>(__args)...);
+#else
+                ::new ((void*)__p) _Tp(_VSTD::forward<_Args>(__args)...);
+#endif
+            }
+
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        static void __destroy(true_type, allocator_type& __a, _Tp* __p)
+            {
+                _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+                __a.destroy(__p);
+                _LIBCPP_SUPPRESS_DEPRECATED_POP
+            }
+    template <class _Tp>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        static void __destroy(false_type, allocator_type&, _Tp* __p)
+            {
+#if _LIBCPP_STD_VER > 17
+                _VSTD::destroy_at(__p);
+#else
+                __p->~_Tp();
+#endif
+            }
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static size_type __max_size(true_type, const allocator_type& __a) _NOEXCEPT
+            {
+                _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+                return __a.max_size();
+                _LIBCPP_SUPPRESS_DEPRECATED_POP
+            }
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static size_type __max_size(false_type, const allocator_type&) _NOEXCEPT
+            {return numeric_limits<size_type>::max() / sizeof(value_type);}
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static allocator_type
+        __select_on_container_copy_construction(true_type, const allocator_type& __a)
+            {return __a.select_on_container_copy_construction();}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static allocator_type
+        __select_on_container_copy_construction(false_type, const allocator_type& __a)
+            {return __a;}
+};
+
+template <class _Traits, class _Tp>
+struct __rebind_alloc_helper
+{
+#ifndef _LIBCPP_CXX03_LANG
+    typedef _LIBCPP_NODEBUG_TYPE typename _Traits::template rebind_alloc<_Tp>        type;
+#else
+    typedef typename _Traits::template rebind_alloc<_Tp>::other type;
+#endif
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_ALLOCATOR_TRAITS_H

libcxx/include/__memory/base.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_BASE_H
+#define _LIBCPP___MEMORY_BASE_H
+
+#include <__config>
+#include <__debug>
+#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
+
+// addressof
+#ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
+
+template <class _Tp>
+inline _LIBCPP_CONSTEXPR_AFTER_CXX14
+_LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
+_Tp*
+addressof(_Tp& __x) _NOEXCEPT
+{
+    return __builtin_addressof(__x);
+}
+
+#else
+
+template <class _Tp>
+inline _LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
+_Tp*
+addressof(_Tp& __x) _NOEXCEPT
+{
+  return reinterpret_cast<_Tp *>(
+      const_cast<char *>(&reinterpret_cast<const volatile char &>(__x)));
+}
+
+#endif // _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
+
+#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
+// Objective-C++ Automatic Reference Counting uses qualified pointers
+// that require special addressof() signatures. When
+// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
+// itself is providing these definitions. Otherwise, we provide them.
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__strong _Tp*
+addressof(__strong _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+
+#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__weak _Tp*
+addressof(__weak _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+#endif
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__autoreleasing _Tp*
+addressof(__autoreleasing _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+__unsafe_unretained _Tp*
+addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
+{
+  return &__x;
+}
+#endif
+
+#if !defined(_LIBCPP_CXX03_LANG)
+template <class _Tp> _Tp* addressof(const _Tp&&) noexcept = delete;
+#endif
+
+// construct_at
+
+#if _LIBCPP_STD_VER > 17
+
+template<class _Tp>
+_LIBCPP_CONSTEXPR_AFTER_CXX17 void* __voidify(_Tp& __ptr) noexcept {
+    return const_cast<void*>(static_cast<const volatile void*>(_VSTD::addressof(__ptr)));
+}
+
+template<class _Tp, class ..._Args, class = decltype(
+    ::new (_VSTD::declval<void*>()) _Tp(_VSTD::declval<_Args>()...)
+)>
+_LIBCPP_INLINE_VISIBILITY
+constexpr _Tp* construct_at(_Tp* __location, _Args&& ...__args) {
+    _LIBCPP_ASSERT(__location, "null pointer given to construct_at");
+    return ::new (_VSTD::__voidify(*__location)) _Tp(_VSTD::forward<_Args>(__args)...);
+}
+
+#endif
+
+// destroy_at
+
+#if _LIBCPP_STD_VER > 14
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void destroy_at(_Tp* __loc) {
+    _LIBCPP_ASSERT(__loc, "null pointer given to destroy_at");
+    __loc->~_Tp();
+}
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_BASE_H

libcxx/include/__memory/pointer_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_POINTER_TRAITS_H
+#define _LIBCPP___MEMORY_POINTER_TRAITS_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, class = void>
+struct __has_element_type : false_type {};
+
+template <class _Tp>
+struct __has_element_type<_Tp,
+              typename __void_t<typename _Tp::element_type>::type> : true_type {};
+
+template <class _Ptr, bool = __has_element_type<_Ptr>::value>
+struct __pointer_traits_element_type;
+
+template <class _Ptr>
+struct __pointer_traits_element_type<_Ptr, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Ptr::element_type type;
+};
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args>
+struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Sp<_Tp, _Args...>::element_type type;
+};
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args>
+struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, false>
+{
+    typedef _LIBCPP_NODEBUG_TYPE _Tp type;
+};
+
+template <class _Tp, class = void>
+struct __has_difference_type : false_type {};
+
+template <class _Tp>
+struct __has_difference_type<_Tp,
+            typename __void_t<typename _Tp::difference_type>::type> : true_type {};
+
+template <class _Ptr, bool = __has_difference_type<_Ptr>::value>
+struct __pointer_traits_difference_type
+{
+    typedef _LIBCPP_NODEBUG_TYPE ptrdiff_t type;
+};
+
+template <class _Ptr>
+struct __pointer_traits_difference_type<_Ptr, true>
+{
+    typedef _LIBCPP_NODEBUG_TYPE typename _Ptr::difference_type type;
+};
+
+template <class _Tp, class _Up>
+struct __has_rebind
+{
+private:
+    struct __two {char __lx; char __lxx;};
+    template <class _Xp> static __two __test(...);
+    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
+    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
+    _LIBCPP_SUPPRESS_DEPRECATED_POP
+public:
+    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+};
+
+template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
+struct __pointer_traits_rebind
+{
+#ifndef _LIBCPP_CXX03_LANG
+    typedef _LIBCPP_NODEBUG_TYPE typename _Tp::template rebind<_Up> type;
+#else
+    typedef _LIBCPP_NODEBUG_TYPE typename _Tp::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, true>
+{
+#ifndef _LIBCPP_CXX03_LANG
+    typedef _LIBCPP_NODEBUG_TYPE typename _Sp<_Tp, _Args...>::template rebind<_Up> type;
+#else
+    typedef _LIBCPP_NODEBUG_TYPE typename _Sp<_Tp, _Args...>::template rebind<_Up>::other type;
+#endif
+};
+
+template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
+struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, false>
+{
+    typedef _Sp<_Up, _Args...> type;
+};
+
+template <class _Ptr>
+struct _LIBCPP_TEMPLATE_VIS pointer_traits
+{
+    typedef _Ptr                                                     pointer;
+    typedef typename __pointer_traits_element_type<pointer>::type    element_type;
+    typedef typename __pointer_traits_difference_type<pointer>::type difference_type;
+
+#ifndef _LIBCPP_CXX03_LANG
+    template <class _Up> using rebind = typename __pointer_traits_rebind<pointer, _Up>::type;
+#else
+    template <class _Up> struct rebind
+        {typedef typename __pointer_traits_rebind<pointer, _Up>::type other;};
+#endif  // _LIBCPP_CXX03_LANG
+
+private:
+    struct __nat {};
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    static pointer pointer_to(typename conditional<is_void<element_type>::value,
+                                           __nat, element_type>::type& __r)
+        {return pointer::pointer_to(__r);}
+};
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS pointer_traits<_Tp*>
+{
+    typedef _Tp*      pointer;
+    typedef _Tp       element_type;
+    typedef ptrdiff_t difference_type;
+
+#ifndef _LIBCPP_CXX03_LANG
+    template <class _Up> using rebind = _Up*;
+#else
+    template <class _Up> struct rebind {typedef _Up* other;};
+#endif
+
+private:
+    struct __nat {};
+public:
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    static pointer pointer_to(typename conditional<is_void<element_type>::value,
+                                      __nat, element_type>::type& __r) _NOEXCEPT
+        {return _VSTD::addressof(__r);}
+};
+
+template <class _From, class _To>
+struct __rebind_pointer {
+#ifndef _LIBCPP_CXX03_LANG
+    typedef typename pointer_traits<_From>::template rebind<_To>        type;
+#else
+    typedef typename pointer_traits<_From>::template rebind<_To>::other type;
+#endif
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_POINTER_TRAITS_H

libcxx/include/exception

 template <class E> void rethrow_if_nested(const E& e);
 
 }  // std
 
 */
 
 #include <__config>
 #include <__availability>
+#include <__memory/base.h>
 #include <cstddef>
 #include <cstdlib>
 #include <type_traits>
 #include <version>
 
 #if defined(_LIBCPP_ABI_VCRUNTIME)
 #include <vcruntime_exception.h>
 #endif

libcxx/include/iterator

 */
 
 #include <__config>
 #include <iosfwd> // for forward declarations of vector and string.
 #include <__functional_base>
 #include <type_traits>
 #include <cstddef>
 #include <initializer_list>
+#include <__memory/base.h>
 #include <version>
 
 #include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 

libcxx/include/memory

 #include <utility>
 #include <limits>
 #include <iterator>
 #include <__functional_base>
 #include <iosfwd>
 #include <tuple>
 #include <stdexcept>
 #include <cstring>
+#include <__memory/allocator_traits.h>
+#include <__memory/base.h>
+#include <__memory/pointer_traits.h>
 #if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 #  include <atomic>
 #endif
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
#if !defined(_LIBCPP_HAS_NO_THREADS) && \
     defined(__ATOMIC_ACQUIRE) &&        \
     (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
     return __atomic_load_n(__value, __ATOMIC_ACQUIRE);
 #else
     return *__value;
 #endif
 }
 
-// addressof moved to <type_traits>
-
-template <class _Tp> class allocator;
-
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
-template <>
-class _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 allocator<void>
-{
-public:
-    typedef void*             pointer;
-    typedef const void*       const_pointer;
-    typedef void              value_type;
-
-    template <class _Up> struct rebind {typedef allocator<_Up> other;};
-};
-
-template <>
-class _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 allocator<const void>
-{
-public:
-    typedef const void*       pointer;
-    typedef const void*       const_pointer;
-    typedef const void        value_type;
-
-    template <class _Up> struct rebind {typedef allocator<_Up> other;};
-};
-#endif
-
-// pointer_traits
-
-template <class _Tp, class = void>
-struct __has_element_type : false_type {};
-
-template <class _Tp>
-struct __has_element_type<_Tp,
-              typename __void_t<typename _Tp::element_type>::type> : true_type {};
-
-template <class _Ptr, bool = __has_element_type<_Ptr>::value>
-struct __pointer_traits_element_type;
-
-template <class _Ptr>
-struct __pointer_traits_element_type<_Ptr, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Ptr::element_type type;
-};
-
-template <template <class, class...> class _Sp, class _Tp, class ..._Args>
-struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Sp<_Tp, _Args...>::element_type type;
-};
-
-template <template <class, class...> class _Sp, class _Tp, class ..._Args>
-struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, false>
-{
-    typedef _LIBCPP_NODEBUG_TYPE _Tp type;
-};
-
-template <class _Tp, class = void>
-struct __has_difference_type : false_type {};
-
-template <class _Tp>
-struct __has_difference_type<_Tp,
-            typename __void_t<typename _Tp::difference_type>::type> : true_type {};
-
-template <class _Ptr, bool = __has_difference_type<_Ptr>::value>
-struct __pointer_traits_difference_type
-{
-    typedef _LIBCPP_NODEBUG_TYPE ptrdiff_t type;
-};
-
-template <class _Ptr>
-struct __pointer_traits_difference_type<_Ptr, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Ptr::difference_type type;
-};
-
-template <class _Tp, class _Up>
-struct __has_rebind
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Xp> static __two __test(...);
-    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
-    _LIBCPP_SUPPRESS_DEPRECATED_POP
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
-
-template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
-struct __pointer_traits_rebind
-{
-#ifndef _LIBCPP_CXX03_LANG
-    typedef _LIBCPP_NODEBUG_TYPE typename _Tp::template rebind<_Up> type;
-#else
-    typedef _LIBCPP_NODEBUG_TYPE typename _Tp::template rebind<_Up>::other type;
-#endif
-};
-
-template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
-struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, true>
-{
-#ifndef _LIBCPP_CXX03_LANG
-    typedef _LIBCPP_NODEBUG_TYPE typename _Sp<_Tp, _Args...>::template rebind<_Up> type;
-#else
-    typedef _LIBCPP_NODEBUG_TYPE typename _Sp<_Tp, _Args...>::template rebind<_Up>::other type;
-#endif
-};
-
-template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
-struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, false>
-{
-    typedef _Sp<_Up, _Args...> type;
-};
-
-template <class _Ptr>
-struct _LIBCPP_TEMPLATE_VIS pointer_traits
-{
-    typedef _Ptr                                                     pointer;
-    typedef typename __pointer_traits_element_type<pointer>::type    element_type;
-    typedef typename __pointer_traits_difference_type<pointer>::type difference_type;
-
-#ifndef _LIBCPP_CXX03_LANG
-    template <class _Up> using rebind = typename __pointer_traits_rebind<pointer, _Up>::type;
-#else
-    template <class _Up> struct rebind
-        {typedef typename __pointer_traits_rebind<pointer, _Up>::type other;};
-#endif  // _LIBCPP_CXX03_LANG
-
-private:
-    struct __nat {};
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    static pointer pointer_to(typename conditional<is_void<element_type>::value,
-                                           __nat, element_type>::type& __r)
-        {return pointer::pointer_to(__r);}
-};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS pointer_traits<_Tp*>
-{
-    typedef _Tp*      pointer;
-    typedef _Tp       element_type;
-    typedef ptrdiff_t difference_type;
-
-#ifndef _LIBCPP_CXX03_LANG
-    template <class _Up> using rebind = _Up*;
-#else
-    template <class _Up> struct rebind {typedef _Up* other;};
-#endif
-
-private:
-    struct __nat {};
-public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static pointer pointer_to(typename conditional<is_void<element_type>::value,
-                                      __nat, element_type>::type& __r) _NOEXCEPT
-        {return _VSTD::addressof(__r);}
-};
-
-template <class _From, class _To>
-struct __rebind_pointer {
-#ifndef _LIBCPP_CXX03_LANG
-    typedef typename pointer_traits<_From>::template rebind<_To>        type;
-#else
-    typedef typename pointer_traits<_From>::template rebind<_To>::other type;
-#endif
-};
-
-// construct_at
-
-#if _LIBCPP_STD_VER > 17
-
-template<class _Tp>
-_LIBCPP_CONSTEXPR_AFTER_CXX17 void* __voidify(_Tp& __ptr) noexcept {
-    return const_cast<void*>(static_cast<const volatile void*>(_VSTD::addressof(__ptr)));
-}
-
-template<class _Tp, class ..._Args, class = decltype(
-    ::new (_VSTD::declval<void*>()) _Tp(_VSTD::declval<_Args>()...)
-)>
-_LIBCPP_INLINE_VISIBILITY
-constexpr _Tp* construct_at(_Tp* __location, _Args&& ...__args) {
-    _LIBCPP_ASSERT(__location, "null pointer given to construct_at");
-    return ::new (_VSTD::__voidify(*__location)) _Tp(_VSTD::forward<_Args>(__args)...);
-}
-
-#endif
-
-// destroy_at
-
-#if _LIBCPP_STD_VER > 14
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void destroy_at(_Tp* __loc) {
-    _LIBCPP_ASSERT(__loc, "null pointer given to destroy_at");
-    __loc->~_Tp();
-}
-
-#endif
-
-// allocator_traits
-
-template <class _Tp, class = void>
-struct __has_pointer_type : false_type {};
-
-template <class _Tp>
-struct __has_pointer_type<_Tp,
-          typename __void_t<typename _Tp::pointer>::type> : true_type {};
-
-namespace __pointer_type_imp
-{
-
-template <class _Tp, class _Dp, bool = __has_pointer_type<_Dp>::value>
-struct __pointer_type
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Dp::pointer type;
-};
-
-template <class _Tp, class _Dp>
-struct __pointer_type<_Tp, _Dp, false>
-{
-    typedef _LIBCPP_NODEBUG_TYPE _Tp* type;
-};
-
-}  // __pointer_type_imp
-
-template <class _Tp, class _Dp>
-struct __pointer_type
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename __pointer_type_imp::__pointer_type<_Tp, typename remove_reference<_Dp>::type>::type type;
-};
-
-template <class _Tp, class = void>
-struct __has_const_pointer : false_type {};
-
-template <class _Tp>
-struct __has_const_pointer<_Tp,
-            typename __void_t<typename _Tp::const_pointer>::type> : true_type {};
-
-template <class _Tp, class _Ptr, class _Alloc, bool = __has_const_pointer<_Alloc>::value>
-struct __const_pointer
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::const_pointer type;
-};
-
-template <class _Tp, class _Ptr, class _Alloc>
-struct __const_pointer<_Tp, _Ptr, _Alloc, false>
-{
-#ifndef _LIBCPP_CXX03_LANG
-    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<const _Tp> type;
-#else
-    typedef typename pointer_traits<_Ptr>::template rebind<const _Tp>::other type;
-#endif
-};
-
-template <class _Tp, class = void>
-struct __has_void_pointer : false_type {};
-
-template <class _Tp>
-struct __has_void_pointer<_Tp,
-               typename __void_t<typename _Tp::void_pointer>::type> : true_type {};
-
-template <class _Ptr, class _Alloc, bool = __has_void_pointer<_Alloc>::value>
-struct __void_pointer
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::void_pointer type;
-};
-
-template <class _Ptr, class _Alloc>
-struct __void_pointer<_Ptr, _Alloc, false>
-{
-#ifndef _LIBCPP_CXX03_LANG
-    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<void> type;
-#else
-    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<void>::other type;
-#endif
-};
-
-template <class _Tp, class = void>
-struct __has_const_void_pointer : false_type {};
-
-template <class _Tp>
-struct __has_const_void_pointer<_Tp,
-            typename __void_t<typename _Tp::const_void_pointer>::type> : true_type {};
-
-template <class _Ptr, class _Alloc, bool = __has_const_void_pointer<_Alloc>::value>
-struct __const_void_pointer
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::const_void_pointer type;
-};
-
-template <class _Ptr, class _Alloc>
-struct __const_void_pointer<_Ptr, _Alloc, false>
-{
-#ifndef _LIBCPP_CXX03_LANG
-    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<const void> type;
-#else
-    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::template rebind<const void>::other type;
-#endif
-};
-
-
 template <bool _UsePointerTraits> struct __to_address_helper;
 
 template <> struct __to_address_helper<true> {
     template <class _Pointer>
     using __return_type = decltype(pointer_traits<_Pointer>::to_address(_VSTD::declval<const _Pointer&>()));
 
     template <class _Pointer>
     _LIBCPP_CONSTEXPR

 inline _LIBCPP_INLINE_VISIBILITY constexpr
 auto
 to_address(const _Pointer& __p) _NOEXCEPT
 {
     return _VSTD::__to_address(__p);
 }
 #endif
 
-template <class _Tp, class = void>
-struct __has_size_type : false_type {};
-
-template <class _Tp>
-struct __has_size_type<_Tp,
-               typename __void_t<typename _Tp::size_type>::type> : true_type {};
-
-template <class _Alloc, class _DiffType, bool = __has_size_type<_Alloc>::value>
-struct __size_type
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename make_unsigned<_DiffType>::type type;
-};
-
-template <class _Alloc, class _DiffType>
-struct __size_type<_Alloc, _DiffType, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::size_type type;
-};
-
-template <class _Tp, class = void>
-struct __has_propagate_on_container_copy_assignment : false_type {};
-
-template <class _Tp>
-struct __has_propagate_on_container_copy_assignment<_Tp,
-    typename __void_t<typename _Tp::propagate_on_container_copy_assignment>::type>
-        : true_type {};
-
-template <class _Alloc, bool = __has_propagate_on_container_copy_assignment<_Alloc>::value>
-struct __propagate_on_container_copy_assignment
-{
-    typedef _LIBCPP_NODEBUG_TYPE false_type type;
-};
-
-template <class _Alloc>
-struct __propagate_on_container_copy_assignment<_Alloc, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::propagate_on_container_copy_assignment type;
-};
-
-template <class _Tp, class = void>
-struct __has_propagate_on_container_move_assignment : false_type {};
-
-template <class _Tp>
-struct __has_propagate_on_container_move_assignment<_Tp,
-           typename __void_t<typename _Tp::propagate_on_container_move_assignment>::type>
-               : true_type {};
-
-template <class _Alloc, bool = __has_propagate_on_container_move_assignment<_Alloc>::value>
-struct __propagate_on_container_move_assignment
-{
-    typedef false_type type;
-};
-
-template <class _Alloc>
-struct __propagate_on_container_move_assignment<_Alloc, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::propagate_on_container_move_assignment type;
-};
-
-template <class _Tp, class = void>
-struct __has_propagate_on_container_swap : false_type {};
-
-template <class _Tp>
-struct __has_propagate_on_container_swap<_Tp,
-           typename __void_t<typename _Tp::propagate_on_container_swap>::type>
-               : true_type {};
-
-template <class _Alloc, bool = __has_propagate_on_container_swap<_Alloc>::value>
-struct __propagate_on_container_swap
-{
-    typedef false_type type;
-};
-
-template <class _Alloc>
-struct __propagate_on_container_swap<_Alloc, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::propagate_on_container_swap type;
-};
-
-template <class _Tp, class = void>
-struct __has_is_always_equal : false_type {};
-
-template <class _Tp>
-struct __has_is_always_equal<_Tp,
-           typename __void_t<typename _Tp::is_always_equal>::type>
-               : true_type {};
-
-template <class _Alloc, bool = __has_is_always_equal<_Alloc>::value>
-struct __is_always_equal
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _VSTD::is_empty<_Alloc>::type type;
-};
-
-template <class _Alloc>
-struct __is_always_equal<_Alloc, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::is_always_equal type;
-};
+template <class _Tp> class allocator;
 
-template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
-struct __has_rebind_other
+#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
+template <>
+class _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 allocator<void>
 {
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Xp> static __two __test(...);
-    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-    template <class _Xp> static char __test(typename _Xp::template rebind<_Up>::other* = 0);
-    _LIBCPP_SUPPRESS_DEPRECATED_POP
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
-
-template <class _Tp, class _Up>
-struct __has_rebind_other<_Tp, _Up, false>
-{
-    static const bool value = false;
-};
-
-template <class _Tp, class _Up, bool = __has_rebind_other<_Tp, _Up>::value>
-struct __allocator_traits_rebind
-{
-    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-    typedef _LIBCPP_NODEBUG_TYPE typename _Tp::template rebind<_Up>::other type;
-    _LIBCPP_SUPPRESS_DEPRECATED_POP
-};
-
-template <template <class, class...> class _Alloc, class _Tp, class ..._Args, class _Up>
-struct __allocator_traits_rebind<_Alloc<_Tp, _Args...>, _Up, true>
-{
-    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc<_Tp, _Args...>::template rebind<_Up>::other type;
-    _LIBCPP_SUPPRESS_DEPRECATED_POP
-};
-
-template <template <class, class...> class _Alloc, class _Tp, class ..._Args, class _Up>
-struct __allocator_traits_rebind<_Alloc<_Tp, _Args...>, _Up, false>
-{
-    typedef _LIBCPP_NODEBUG_TYPE _Alloc<_Up, _Args...> type;
-};
-
-#ifndef _LIBCPP_CXX03_LANG
-
-_LIBCPP_SUPPRESS_DEPRECATED_PUSH
-template <class _Alloc, class _SizeType, class _ConstVoidPtr>
-auto
-__has_allocate_hint_test(_Alloc&& __a, _SizeType&& __sz, _ConstVoidPtr&& __p)
-    -> decltype((void)__a.allocate(__sz, __p), true_type());
-_LIBCPP_SUPPRESS_DEPRECATED_POP
-
-template <class _Alloc, class _SizeType, class _ConstVoidPtr>
-auto
-__has_allocate_hint_test(const _Alloc& __a, _SizeType&& __sz, _ConstVoidPtr&& __p)
-    -> false_type;
-
-template <class _Alloc, class _SizeType, class _ConstVoidPtr>
-struct __has_allocate_hint
-    : decltype(_VSTD::__has_allocate_hint_test(declval<_Alloc>(),
-                                               declval<_SizeType>(),
-                                               declval<_ConstVoidPtr>()))
-{
-};
-
-#else  // _LIBCPP_CXX03_LANG
-
-template <class _Alloc, class _SizeType, class _ConstVoidPtr>
-struct __has_allocate_hint
-    : true_type
-{
-};
-
-#endif  // _LIBCPP_CXX03_LANG
-
-_LIBCPP_SUPPRESS_DEPRECATED_PUSH
-template <class _Alloc, class ..._Args,
-    class = decltype(_VSTD::declval<_Alloc>().construct(_VSTD::declval<_Args>()...))>
-static true_type __test_has_construct(int);
-_LIBCPP_SUPPRESS_DEPRECATED_POP
-
-template <class _Alloc, class...>
-static false_type __test_has_construct(...);
-
-template <class _Alloc, class ..._Args>
-struct __has_construct : decltype(__test_has_construct<_Alloc, _Args...>(0)) {};
-
-#if !defined(_LIBCPP_CXX03_LANG)
-
-_LIBCPP_SUPPRESS_DEPRECATED_PUSH
-template <class _Alloc, class _Pointer>
-auto
-__has_destroy_test(_Alloc&& __a, _Pointer&& __p)
-    -> decltype(__a.destroy(__p), true_type());
-_LIBCPP_SUPPRESS_DEPRECATED_POP
-
-template <class _Alloc, class _Pointer>
-auto
-__has_destroy_test(const _Alloc& __a, _Pointer&& __p)
-    -> false_type;
-
-template <class _Alloc, class _Pointer>
-struct __has_destroy
-    : decltype(_VSTD::__has_destroy_test(declval<_Alloc>(),
-                                         declval<_Pointer>()))
-{
-};
-
-_LIBCPP_SUPPRESS_DEPRECATED_PUSH
-template <class _Alloc>
-auto
-__has_max_size_test(_Alloc&& __a)
-    -> decltype(__a.max_size(), true_type());
-_LIBCPP_SUPPRESS_DEPRECATED_POP
-
-template <class _Alloc>
-auto
-__has_max_size_test(const volatile _Alloc& __a)
-    -> false_type;
-
-template <class _Alloc>
-struct __has_max_size
-    : decltype(_VSTD::__has_max_size_test(declval<_Alloc&>()))
-{
-};
-
-template <class _Alloc>
-auto
-__has_select_on_container_copy_construction_test(_Alloc&& __a)
-    -> decltype(__a.select_on_container_copy_construction(), true_type());
-
-template <class _Alloc>
-auto
-__has_select_on_container_copy_construction_test(const volatile _Alloc& __a)
-    -> false_type;
-
-template <class _Alloc>
-struct __has_select_on_container_copy_construction
-    : decltype(_VSTD::__has_select_on_container_copy_construction_test(declval<_Alloc&>()))
-{
-};
-
-#else  // _LIBCPP_CXX03_LANG
-
-template <class _Alloc, class _Pointer, class = void>
-struct __has_destroy : false_type {};
-
-template <class _Alloc, class _Pointer>
-struct __has_destroy<_Alloc, _Pointer, typename __void_t<
-    decltype(_VSTD::declval<_Alloc>().destroy(_VSTD::declval<_Pointer>()))
->::type> : true_type {};
-
-template <class _Alloc>
-struct __has_max_size
-    : true_type
-{
-};
-
-template <class _Alloc>
-struct __has_select_on_container_copy_construction
-    : false_type
-{
-};
-
-#endif  // _LIBCPP_CXX03_LANG
-
-template <class _Alloc, class _Ptr, bool = __has_difference_type<_Alloc>::value>
-struct __alloc_traits_difference_type
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename pointer_traits<_Ptr>::difference_type type;
-};
+    typedef void*             pointer;
+    typedef const void*       const_pointer;
+    typedef void              value_type;
 
-template <class _Alloc, class _Ptr>
-struct __alloc_traits_difference_type<_Alloc, _Ptr, true>
-{
-    typedef _LIBCPP_NODEBUG_TYPE typename _Alloc::difference_type type;
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
 };
 
-template <class _Tp>
-struct __is_default_allocator : false_type {};
-
-template <class _Tp>
-struct __is_default_allocator<_VSTD::allocator<_Tp> > : true_type {};
-
-
-
-template <class _Alloc,
-    bool = __has_construct<_Alloc, typename _Alloc::value_type*,  typename _Alloc::value_type&&>::value && !__is_default_allocator<_Alloc>::value
-    >
-struct __is_cpp17_move_insertable;
-template <class _Alloc>
-struct __is_cpp17_move_insertable<_Alloc, true> : true_type {};
-template <class _Alloc>
-struct __is_cpp17_move_insertable<_Alloc, false> : is_move_constructible<typename _Alloc::value_type> {};
-
-template <class _Alloc,
-    bool = __has_construct<_Alloc, typename _Alloc::value_type*, const typename _Alloc::value_type&>::value && !__is_default_allocator<_Alloc>::value
-    >
-struct __is_cpp17_copy_insertable;
-template <class _Alloc>
-struct __is_cpp17_copy_insertable<_Alloc, true> : __is_cpp17_move_insertable<_Alloc> {};
-template <class _Alloc>
-struct __is_cpp17_copy_insertable<_Alloc, false> : integral_constant<bool,
-    is_copy_constructible<typename _Alloc::value_type>::value &&
-    __is_cpp17_move_insertable<_Alloc>::value>
-  {};
-
-
-
-template <class _Alloc>
-struct _LIBCPP_TEMPLATE_VIS allocator_traits
-{
-    typedef _Alloc                              allocator_type;
-    typedef typename allocator_type::value_type value_type;
-
-    typedef typename __pointer_type<value_type, allocator_type>::type pointer;
-    typedef typename __const_pointer<value_type, pointer, allocator_type>::type const_pointer;
-    typedef typename __void_pointer<pointer, allocator_type>::type void_pointer;
-    typedef typename __const_void_pointer<pointer, allocator_type>::type const_void_pointer;
-
-    typedef typename __alloc_traits_difference_type<allocator_type, pointer>::type difference_type;
-    typedef typename __size_type<allocator_type, difference_type>::type size_type;
-
-    typedef typename __propagate_on_container_copy_assignment<allocator_type>::type
-                     propagate_on_container_copy_assignment;
-    typedef typename __propagate_on_container_move_assignment<allocator_type>::type
-                     propagate_on_container_move_assignment;
-    typedef typename __propagate_on_container_swap<allocator_type>::type
-                     propagate_on_container_swap;
-    typedef typename __is_always_equal<allocator_type>::type
-                     is_always_equal;
-
-#ifndef _LIBCPP_CXX03_LANG
-    template <class _Tp> using rebind_alloc =
-                  typename __allocator_traits_rebind<allocator_type, _Tp>::type;
-    template <class _Tp> using rebind_traits = allocator_traits<rebind_alloc<_Tp> >;
-#else  // _LIBCPP_CXX03_LANG
-    template <class _Tp> struct rebind_alloc
-        {typedef typename __allocator_traits_rebind<allocator_type, _Tp>::type other;};
-    template <class _Tp> struct rebind_traits
-        {typedef allocator_traits<typename rebind_alloc<_Tp>::other> other;};
-#endif  // _LIBCPP_CXX03_LANG
-
-    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static pointer allocate(allocator_type& __a, size_type __n)
-        {return __a.allocate(__n);}
-    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
-        {return __allocate(__a, __n, __hint,
-            __has_allocate_hint<allocator_type, size_type, const_void_pointer>());}
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static void deallocate(allocator_type& __a, pointer __p, size_type __n) _NOEXCEPT
-        {__a.deallocate(__p, __n);}
-
-    template <class _Tp, class... _Args>
-        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-        static void construct(allocator_type& __a, _Tp* __p, _Args&&... __args)
-            {__construct(__has_construct<allocator_type, _Tp*, _Args...>(),
-                         __a, __p, _VSTD::forward<_Args>(__args)...);}
-
-    template <class _Tp>
-        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-        static void destroy(allocator_type& __a, _Tp* __p)
-            {__destroy(__has_destroy<allocator_type, _Tp*>(), __a, __p);}
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static size_type max_size(const allocator_type& __a) _NOEXCEPT
-        {return __max_size(__has_max_size<const allocator_type>(), __a);}
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static allocator_type
-        select_on_container_copy_construction(const allocator_type& __a)
-            {return __select_on_container_copy_construction(
-                __has_select_on_container_copy_construction<const allocator_type>(),
-                __a);}
-
-private:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static pointer __allocate(allocator_type& __a, size_type __n,
-        const_void_pointer __hint, true_type)
-        {
-            _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-            return __a.allocate(__n, __hint);
-            _LIBCPP_SUPPRESS_DEPRECATED_POP
-        }
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static pointer __allocate(allocator_type& __a, size_type __n,
-        const_void_pointer, false_type)
-        {return __a.allocate(__n);}
-
-    template <class _Tp, class... _Args>
-        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-        static void __construct(true_type, allocator_type& __a, _Tp* __p, _Args&&... __args)
-            {
-                _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-                __a.construct(__p, _VSTD::forward<_Args>(__args)...);
-                _LIBCPP_SUPPRESS_DEPRECATED_POP
-            }
-
-    template <class _Tp, class... _Args>
-        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-        static void __construct(false_type, allocator_type&, _Tp* __p, _Args&&... __args)
-            {
-#if _LIBCPP_STD_VER > 17
-                _VSTD::construct_at(__p, _VSTD::forward<_Args>(__args)...);
-#else
-                ::new ((void*)__p) _Tp(_VSTD::forward<_Args>(__args)...);
-#endif
-            }
-
-    template <class _Tp>
-        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-        static void __destroy(true_type, allocator_type& __a, _Tp* __p)
-            {
-                _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-                __a.destroy(__p);
-                _LIBCPP_SUPPRESS_DEPRECATED_POP
-            }
-    template <class _Tp>
-        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-        static void __destroy(false_type, allocator_type&, _Tp* __p)
-            {
-#if _LIBCPP_STD_VER > 17
-                _VSTD::destroy_at(__p);
-#else
-                __p->~_Tp();
-#endif
-            }
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static size_type __max_size(true_type, const allocator_type& __a) _NOEXCEPT
-            {
-                _LIBCPP_SUPPRESS_DEPRECATED_PUSH
-                return __a.max_size();
-                _LIBCPP_SUPPRESS_DEPRECATED_POP
-            }
-
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static size_type __max_size(false_type, const allocator_type&) _NOEXCEPT
-            {return numeric_limits<size_type>::max() / sizeof(value_type);}
+template <>
+class _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 allocator<const void>
+public:
+    typedef const void*       pointer;
+    typedef const void*       const_pointer;
+    typedef const void        value_type;
 
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static allocator_type
-        __select_on_container_copy_construction(true_type, const allocator_type& __a)
-            {return __a.select_on_container_copy_construction();}
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-    static allocator_type
-        __select_on_container_copy_construction(false_type, const allocator_type& __a)
-            {return __a;}
+    template <class _Up> struct rebind {typedef allocator<_Up> other;};
 };
-
-template <class _Traits, class _Tp>
-struct __rebind_alloc_helper
-{
-#ifndef _LIBCPP_CXX03_LANG
-    typedef _LIBCPP_NODEBUG_TYPE typename _Traits::template rebind_alloc<_Tp>        type;
-#else
-    typedef typename _Traits::template rebind_alloc<_Tp>::other type;
 #endif
-};
 
 // allocator
 
 template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator
 {
 public:
     typedef size_t      size_type;

libcxx/include/type_traits

 using __test_for_primary_template = _EnableIf<
     _IsSame<_Tp, typename _Tp::__primary_template>::value
   >;
 template <class _Tp>
 using __is_primary_template = _IsValidExpansion<
     __test_for_primary_template, _Tp
   >;
 
-// addressof
-#ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
-
-template <class _Tp>
-inline _LIBCPP_CONSTEXPR_AFTER_CXX14
-_LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
-_Tp*
-addressof(_Tp& __x) _NOEXCEPT
-{
-    return __builtin_addressof(__x);
-}
-
-#else
-
-template <class _Tp>
-inline _LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
-_Tp*
-addressof(_Tp& __x) _NOEXCEPT
-{
-  return reinterpret_cast<_Tp *>(
-      const_cast<char *>(&reinterpret_cast<const volatile char &>(__x)));
-}
-
-#endif // _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
-
-#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
-// Objective-C++ Automatic Reference Counting uses qualified pointers
-// that require special addressof() signatures. When
-// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
-// itself is providing these definitions. Otherwise, we provide them.
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-__strong _Tp*
-addressof(__strong _Tp& __x) _NOEXCEPT
-{
-  return &__x;
-}
-
-#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-__weak _Tp*
-addressof(__weak _Tp& __x) _NOEXCEPT
-{
-  return &__x;
-}
-#endif
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-__autoreleasing _Tp*
-addressof(__autoreleasing _Tp& __x) _NOEXCEPT
-{
-  return &__x;
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-__unsafe_unretained _Tp*
-addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
-{
-  return &__x;
-}
-#endif
-
-#if !defined(_LIBCPP_CXX03_LANG)
-template <class _Tp> _Tp* addressof(const _Tp&&) noexcept = delete;
-#endif
-
 struct __two {char __lx[2];};
 
 // helper class:
 
 // is_const
 
 #if __has_keyword(__is_const)
 

libcxx/test/std/containers/sequences/vector/vector.cons/copy.move_only.verify.cpp

struct move_only
     move_only() = default;
     move_only(move_only&&) = default;
     move_only& operator=(move_only&&) = default;
 };
 
 int main(int, char**)
 {
     std::vector<move_only> v;
-    std::vector<move_only> copy = v; // expected-error-re@memory:* {{{{(no matching function for call to 'construct_at')|(call to implicitly-deleted copy constructor of 'move_only')}}}}
+    std::vector<move_only> copy = v; // expected-error-re@* {{{{(no matching function for call to 'construct_at')|(call to implicitly-deleted copy constructor of 'move_only')}}}}
     return 0;
 }