libstdc++-v3/include/std/memory - gcc - Git at Google

 // <memory> -*- C++ -*-

 // Copyright (C) 2001-2020 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
 // terms of the GNU General Public License as published by the
 // Free Software Foundation; either version 3, or (at your option)
 // any later version.

 // This library is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.

 // Under Section 7 of GPL version 3, you are granted additional
 // permissions described in the GCC Runtime Library Exception, version
 // 3.1, as published by the Free Software Foundation.

 // You should have received a copy of the GNU General Public License and
 // a copy of the GCC Runtime Library Exception along with this program;
 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 // <http://www.gnu.org/licenses/>.

 /*
  * Copyright (c) 1997-1999
  * Silicon Graphics Computer Systems, Inc.
  *
  * Permission to use, copy, modify, distribute and sell this software
  * and its documentation for any purpose is hereby granted without fee,
  * provided that the above copyright notice appear in all copies and
  * that both that copyright notice and this permission notice appear
  * in supporting documentation.  Silicon Graphics makes no
  * representations about the suitability of this software for any
  * purpose.  It is provided "as is" without express or implied warranty.
  *
  */

 /** @file include/memory
  *  This is a Standard C++ Library header.
  *  @ingroup memory
  */

 #ifndef _GLIBCXX_MEMORY
 #define _GLIBCXX_MEMORY 1

 #pragma GCC system_header

 /**
  * @defgroup memory Memory
  * @ingroup utilities
  *
  * Components for memory allocation, deallocation, and management.
  */

 /**
  * @defgroup pointer_abstractions Pointer Abstractions
  * @ingroup memory
  *
  * Smart pointers, etc.
  */

 #include <bits/stl_algobase.h>
 #include <bits/allocator.h>
 #include <bits/stl_construct.h>
 #include <bits/stl_uninitialized.h>
 #include <bits/stl_tempbuf.h>
 #include <bits/stl_raw_storage_iter.h>
 #include <bits/ranges_uninitialized.h>

 #if __cplusplus >= 201103L
 #  include <exception>        	  // std::exception
 #  include <typeinfo>         	  // std::type_info in get_deleter
 #  include <iosfwd>           	  // std::basic_ostream
 #  include <ext/atomicity.h>
 #  include <ext/concurrence.h>
 #  include <bits/functexcept.h>
 #  include <bits/stl_function.h>  // std::less
 #  include <bits/uses_allocator.h>
 #  include <bits/alloc_traits.h>
 #  include <type_traits>
 #  include <debug/debug.h>
 #  include <bits/unique_ptr.h>
 #  include <bits/shared_ptr.h>
 #  include <bits/shared_ptr_atomic.h>
 #  if _GLIBCXX_USE_DEPRECATED
 #    include <backward/auto_ptr.h>
 #  endif
 #else
 #  include <backward/auto_ptr.h>
 #endif

 #if __cplusplus >= 201103L
 #include <cstdint>
 #if __cplusplus > 201703L
 # include <bit>			// for has_single_bit
 # include <new>			// for placement operator new
 # include <tuple>		// for tuple, make_tuple, make_from_tuple
 #endif
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION

 /**
  *  @brief Fit aligned storage in buffer.
  *  @ingroup memory
  *
  *  This function tries to fit @a __size bytes of storage with alignment
  *  @a __align into the buffer @a __ptr of size @a __space bytes.  If such
  *  a buffer fits then @a __ptr is changed to point to the first byte of the
  *  aligned storage and @a __space is reduced by the bytes used for alignment.
  *
  *  C++11 20.6.5 [ptr.align]
  *
  *  @param __align   A fundamental or extended alignment value.
  *  @param __size    Size of the aligned storage required.
  *  @param __ptr     Pointer to a buffer of @a __space bytes.
  *  @param __space   Size of the buffer pointed to by @a __ptr.
  *  @return the updated pointer if the aligned storage fits, otherwise nullptr.
  *
  */
 inline void*
 align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
 {
 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
   const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
 #else
   // Cannot use std::uintptr_t so assume that std::size_t can be used instead.
   static_assert(sizeof(size_t) >= sizeof(void*),
       "std::size_t must be a suitable substitute for std::uintptr_t");
   const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
 #endif
   const auto __aligned = (__intptr - 1u + __align) & -__align;
   const auto __diff = __aligned - __intptr;
   if ((__size + __diff) > __space)
     return nullptr;
   else
     {
       __space -= __diff;
       return __ptr = reinterpret_cast<void*>(__aligned);
     }
 }

 /** @defgroup ptr_safety Pointer Safety and Garbage Collection
  *  @ingroup memory
  *
  * Utilities to assist with garbage collection in an implementation
  * that supports <em>strict pointer safety</em>.
  * This implementation only supports <em>relaxed pointer safety</em>
  * and so these functions have no effect.
  *
  * C++11 20.6.4 [util.dynamic.safety], Pointer safety
  *
  * @{
  */

 /// Constants representing the different types of pointer safety.
 enum class pointer_safety { relaxed, preferred, strict };

 /// Inform a garbage collector that an object is still in use.
 inline void
 declare_reachable(void*) { }

 /// Unregister an object previously registered with declare_reachable.
 template <typename _Tp>
   inline _Tp*
   undeclare_reachable(_Tp* __p) { return __p; }

 /// Inform a garbage collector that a region of memory need not be traced.
 inline void
 declare_no_pointers(char*, size_t) { }

 /// Unregister a range previously registered with declare_no_pointers.
 inline void
 undeclare_no_pointers(char*, size_t) { }

 /// The type of pointer safety supported by the implementation.
 inline pointer_safety
 get_pointer_safety() noexcept { return pointer_safety::relaxed; }
 /// @}

 #if __cplusplus > 201703L
 #define __cpp_lib_assume_aligned 201811L
   /** @brief Inform the compiler that a pointer is aligned.
    *
    *  @tparam _Align An alignment value (i.e. a power of two)
    *  @tparam _Tp    An object type
    *  @param  __ptr  A pointer that is aligned to _Align
    *
    *  C++20 20.10.6 [ptr.align]
    *
    *  @ingroup memory
    */
   template<size_t _Align, class _Tp>
     [[nodiscard,__gnu__::__always_inline__]]
     constexpr _Tp*
     assume_aligned(_Tp* __ptr) noexcept
     {
       static_assert(std::has_single_bit(_Align));
       if (std::is_constant_evaluated())
 	return __ptr;
       else
 	{
 	  // This function is expected to be used in hot code, where
 	  // __glibcxx_assert would add unwanted overhead.
 	  _GLIBCXX_DEBUG_ASSERT((std::uintptr_t)__ptr % _Align == 0);
 	  return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
 	}
     }
 #endif // C++2a

 #if __cplusplus > 201703L
   template<typename _Tp>
     struct __is_pair : false_type { };
   template<typename _Tp, typename _Up>
     struct __is_pair<pair<_Tp, _Up>> : true_type { };
   template<typename _Tp, typename _Up>
     struct __is_pair<const pair<_Tp, _Up>> : true_type { };

 /** @addtogroup allocators
  *  @{
  */
   template<typename _Tp, typename __ = _Require<__not_<__is_pair<_Tp>>>,
 	   typename _Alloc, typename... _Args>
     constexpr auto
     __uses_alloc_args(const _Alloc& __a, _Args&&... __args) noexcept
     {
       if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
 	{
 	  if constexpr (is_constructible_v<_Tp, allocator_arg_t,
 					   const _Alloc&, _Args...>)
 	    {
 	      return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
 		  allocator_arg, __a, std::forward<_Args>(__args)...);
 	    }
 	  else
 	    {
 	      static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
 		  "construction with an allocator must be possible"
 		  " if uses_allocator is true");

 	      return tuple<_Args&&..., const _Alloc&>(
 		  std::forward<_Args>(__args)..., __a);
 	    }
 	}
       else
 	{
 	  static_assert(is_constructible_v<_Tp, _Args...>);

 	  return tuple<_Args&&...>(std::forward<_Args>(__args)...);
 	}
     }

 #if __cpp_concepts
   template<typename _Tp>
     concept _Std_pair = __is_pair<_Tp>::value;
 #endif

 // This is a temporary workaround until -fconcepts is implied by -std=gnu++2a
 #if __cpp_concepts
 # define _GLIBCXX_STD_PAIR_CONSTRAINT(T) _Std_pair T
 # define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) _Std_pair T
 #else
 # define _GLIBCXX_STD_PAIR_CONSTRAINT(T) \
       typename T, typename __ = _Require<__is_pair<T>>
 # define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) typename T, typename
 #endif

   template<typename _Tp,
 #if ! __cpp_concepts
 	   typename __ = _Require<__not_<__is_pair<_Tp>>>,
 #endif
 	   typename _Alloc, typename... _Args>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a,
 				     _Args&&... __args) noexcept
 #if __cpp_concepts
     requires (! _Std_pair<_Tp>)
 #endif
     {
       return std::__uses_alloc_args<_Tp>(__a, std::forward<_Args>(__args)...);
     }

   template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
 	   typename _Tuple1, typename _Tuple2>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
 				     _Tuple1&& __x, _Tuple2&& __y) noexcept;

   template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc>
     constexpr auto
     uses_allocator_construction_args(const _Alloc&) noexcept;

   template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
 	   typename _Up, typename _Vp>
     constexpr auto
     uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;

   template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
 	   typename _Up, typename _Vp>
     constexpr auto
     uses_allocator_construction_args(const _Alloc&,
 				     const pair<_Up, _Vp>&) noexcept;

   template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
 	   typename _Up, typename _Vp>
     constexpr auto
     uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;

   template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
 	   typename _Tuple1, typename _Tuple2>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
 				     _Tuple1&& __x, _Tuple2&& __y) noexcept
     {
       using _Tp1 = typename _Tp::first_type;
       using _Tp2 = typename _Tp::second_type;

       return std::make_tuple(piecewise_construct,
 	  std::apply([&__a](auto&&... __args1) {
 	      return std::uses_allocator_construction_args<_Tp1>(
 		  __a, std::forward<decltype(__args1)>(__args1)...);
 	  }, std::forward<_Tuple1>(__x)),
 	  std::apply([&__a](auto&&... __args2) {
 	      return std::uses_allocator_construction_args<_Tp2>(
 		  __a, std::forward<decltype(__args2)>(__args2)...);
 	  }, std::forward<_Tuple2>(__y)));
     }

   template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a) noexcept
     {
       using _Tp1 = typename _Tp::first_type;
       using _Tp2 = typename _Tp::second_type;

       return std::make_tuple(piecewise_construct,
 	  std::uses_allocator_construction_args<_Tp1>(__a),
 	  std::uses_allocator_construction_args<_Tp2>(__a));
     }

   template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
 	   typename _Up, typename _Vp>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
       noexcept
     {
       using _Tp1 = typename _Tp::first_type;
       using _Tp2 = typename _Tp::second_type;

       return std::make_tuple(piecewise_construct,
 	  std::uses_allocator_construction_args<_Tp1>(__a,
 	    std::forward<_Up>(__u)),
 	  std::uses_allocator_construction_args<_Tp2>(__a,
 	    std::forward<_Vp>(__v)));
     }

   template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
 	   typename _Up, typename _Vp>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a,
 				     const pair<_Up, _Vp>& __pr) noexcept
     {
       using _Tp1 = typename _Tp::first_type;
       using _Tp2 = typename _Tp::second_type;

       return std::make_tuple(piecewise_construct,
 	  std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
 	  std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
     }

   template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
 	   typename _Up, typename _Vp>
     constexpr auto
     uses_allocator_construction_args(const _Alloc& __a,
 				     pair<_Up, _Vp>&& __pr) noexcept
     {
       using _Tp1 = typename _Tp::first_type;
       using _Tp2 = typename _Tp::second_type;

       return std::make_tuple(piecewise_construct,
 	  std::uses_allocator_construction_args<_Tp1>(__a,
 	    std::move(__pr).first),
 	  std::uses_allocator_construction_args<_Tp2>(__a,
 	    std::move(__pr).second));
     }

   template<typename _Tp, typename _Alloc, typename... _Args>
     inline _Tp
     make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
     {
       return std::make_from_tuple<_Tp>(
 	  std::uses_allocator_construction_args<_Tp>(__a,
 	    std::forward<_Args>(__args)...));
     }

   template<typename _Tp, typename _Alloc, typename... _Args>
     inline _Tp*
     uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
 					    _Args&&... __args)
     {
       return std::apply([&](auto&&... __xs) {
 	return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
       }, std::uses_allocator_construction_args<_Tp>(__a,
 	std::forward<_Args>(__args)...));
     }
 // @}

 #endif // C++2a

 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 #endif // C++11

 #if __cplusplus > 201402L
 // Parallel STL algorithms
 # if _PSTL_EXECUTION_POLICIES_DEFINED
 // If <execution> has already been included, pull in implementations
 #  include <pstl/glue_memory_impl.h>
 # else
 // Otherwise just pull in forward declarations
 #  include <pstl/glue_memory_defs.h>
 # endif

 // Feature test macro for parallel algorithms
 # define __cpp_lib_parallel_algorithm 201603L
 #endif // C++17

 #endif /* _GLIBCXX_MEMORY */
	// <memory> -- C++ --

	// Copyright (C) 2001-2020 Free Software Foundation, Inc.
	//
	// This file is part of the GNU ISO C++ Library. This library is free
	// software; you can redistribute it and/or modify it under the
	// terms of the GNU General Public License as published by the
	// Free Software Foundation; either version 3, or (at your option)
	// any later version.

	// This library is distributed in the hope that it will be useful,
	// but WITHOUT ANY WARRANTY; without even the implied warranty of
	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	// GNU General Public License for more details.

	// Under Section 7 of GPL version 3, you are granted additional
	// permissions described in the GCC Runtime Library Exception, version
	// 3.1, as published by the Free Software Foundation.

	// You should have received a copy of the GNU General Public License and
	// a copy of the GCC Runtime Library Exception along with this program;
	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
	// <http://www.gnu.org/licenses/>.

	/*
	* Copyright (c) 1997-1999
	* Silicon Graphics Computer Systems, Inc.
	*
	* Permission to use, copy, modify, distribute and sell this software
	* and its documentation for any purpose is hereby granted without fee,
	* provided that the above copyright notice appear in all copies and
	* that both that copyright notice and this permission notice appear
	* in supporting documentation. Silicon Graphics makes no
	* representations about the suitability of this software for any
	* purpose. It is provided "as is" without express or implied warranty.
	*
	*/

	/** @file include/memory
	* This is a Standard C++ Library header.
	* @ingroup memory
	*/

	#ifndef _GLIBCXX_MEMORY
	#define _GLIBCXX_MEMORY 1

	#pragma GCC system_header

	/**
	* @defgroup memory Memory
	* @ingroup utilities
	*
	* Components for memory allocation, deallocation, and management.
	*/

	/**
	* @defgroup pointer_abstractions Pointer Abstractions
	* @ingroup memory
	*
	* Smart pointers, etc.
	*/

	#include <bits/stl_algobase.h>
	#include <bits/allocator.h>
	#include <bits/stl_construct.h>
	#include <bits/stl_uninitialized.h>
	#include <bits/stl_tempbuf.h>
	#include <bits/stl_raw_storage_iter.h>
	#include <bits/ranges_uninitialized.h>

	#if __cplusplus >= 201103L
	# include <exception> // std::exception
	# include <typeinfo> // std::type_info in get_deleter
	# include <iosfwd> // std::basic_ostream
	# include <ext/atomicity.h>
	# include <ext/concurrence.h>
	# include <bits/functexcept.h>
	# include <bits/stl_function.h> // std::less
	# include <bits/uses_allocator.h>
	# include <bits/alloc_traits.h>
	# include <type_traits>
	# include <debug/debug.h>
	# include <bits/unique_ptr.h>
	# include <bits/shared_ptr.h>
	# include <bits/shared_ptr_atomic.h>
	# if _GLIBCXX_USE_DEPRECATED
	# include <backward/auto_ptr.h>
	# endif
	#else
	# include <backward/auto_ptr.h>
	#endif

	#if __cplusplus >= 201103L
	#include <cstdint>
	#if __cplusplus > 201703L
	# include <bit> // for has_single_bit
	# include <new> // for placement operator new
	# include <tuple> // for tuple, make_tuple, make_from_tuple
	#endif
	namespace std _GLIBCXX_VISIBILITY(default)
	{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION

	/**
	* @brief Fit aligned storage in buffer.
	* @ingroup memory
	*
	* This function tries to fit @a __size bytes of storage with alignment
	* @a __align into the buffer @a __ptr of size @a __space bytes. If such
	* a buffer fits then @a __ptr is changed to point to the first byte of the
	* aligned storage and @a __space is reduced by the bytes used for alignment.
	*
	* C++11 20.6.5 [ptr.align]
	*
	* @param __align A fundamental or extended alignment value.
	* @param __size Size of the aligned storage required.
	* @param __ptr Pointer to a buffer of @a __space bytes.
	* @param __space Size of the buffer pointed to by @a __ptr.
	* @return the updated pointer if the aligned storage fits, otherwise nullptr.
	*
	*/
	inline void*
	align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
	{
	#ifdef _GLIBCXX_USE_C99_STDINT_TR1
	const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
	#else
	// Cannot use std::uintptr_t so assume that std::size_t can be used instead.
	static_assert(sizeof(size_t) >= sizeof(void*),
	"std::size_t must be a suitable substitute for std::uintptr_t");
	const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
	#endif
	const auto __aligned = (__intptr - 1u + __align) & -__align;
	const auto __diff = __aligned - __intptr;
	if ((__size + __diff) > __space)
	return nullptr;
	else
	{
	__space -= __diff;
	return __ptr = reinterpret_cast<void*>(__aligned);
	}
	}

	/** @defgroup ptr_safety Pointer Safety and Garbage Collection
	* @ingroup memory
	*
	* Utilities to assist with garbage collection in an implementation
	* that supports <em>strict pointer safety</em>.
	* This implementation only supports <em>relaxed pointer safety</em>
	* and so these functions have no effect.
	*
	* C++11 20.6.4 [util.dynamic.safety], Pointer safety
	*
	* @{
	*/

	/// Constants representing the different types of pointer safety.
	enum class pointer_safety { relaxed, preferred, strict };

	/// Inform a garbage collector that an object is still in use.
	inline void
	declare_reachable(void*) { }

	/// Unregister an object previously registered with declare_reachable.
	template <typename _Tp>
	inline _Tp*
	undeclare_reachable(_Tp* __p) { return __p; }

	/// Inform a garbage collector that a region of memory need not be traced.
	inline void
	declare_no_pointers(char*, size_t) { }

	/// Unregister a range previously registered with declare_no_pointers.
	inline void
	undeclare_no_pointers(char*, size_t) { }

	/// The type of pointer safety supported by the implementation.
	inline pointer_safety
	get_pointer_safety() noexcept { return pointer_safety::relaxed; }
	/// @}

	#if __cplusplus > 201703L
	#define __cpp_lib_assume_aligned 201811L
	/** @brief Inform the compiler that a pointer is aligned.
	*
	* @tparam _Align An alignment value (i.e. a power of two)
	* @tparam _Tp An object type
	* @param __ptr A pointer that is aligned to _Align
	*
	* C++20 20.10.6 [ptr.align]
	*
	* @ingroup memory
	*/
	template<size_t _Align, class _Tp>
	[[nodiscard,__gnu__::__always_inline__]]
	constexpr _Tp*
	assume_aligned(_Tp* __ptr) noexcept
	{
	static_assert(std::has_single_bit(_Align));
	if (std::is_constant_evaluated())
	return __ptr;
	else
	{
	// This function is expected to be used in hot code, where
	// __glibcxx_assert would add unwanted overhead.
	_GLIBCXX_DEBUG_ASSERT((std::uintptr_t)__ptr % _Align == 0);
	return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
	}
	}
	#endif // C++2a

	#if __cplusplus > 201703L
	template<typename _Tp>
	struct __is_pair : false_type { };
	template<typename _Tp, typename _Up>
	struct __is_pair<pair<_Tp, _Up>> : true_type { };
	template<typename _Tp, typename _Up>
	struct __is_pair<const pair<_Tp, _Up>> : true_type { };

	/** @addtogroup allocators
	* @{
	*/
	template<typename _Tp, typename __ = _Require<__not_<__is_pair<_Tp>>>,
	typename _Alloc, typename... _Args>
	constexpr auto
	__uses_alloc_args(const _Alloc& __a, _Args&&... __args) noexcept
	{
	if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
	{
	if constexpr (is_constructible_v<_Tp, allocator_arg_t,
	const _Alloc&, _Args...>)
	{
	return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
	allocator_arg, __a, std::forward<_Args>(__args)...);
	}
	else
	{
	static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
	"construction with an allocator must be possible"
	" if uses_allocator is true");

	return tuple<_Args&&..., const _Alloc&>(
	std::forward<_Args>(__args)..., __a);
	}
	}
	else
	{
	static_assert(is_constructible_v<_Tp, _Args...>);

	return tuple<_Args&&...>(std::forward<_Args>(__args)...);
	}
	}

	#if __cpp_concepts
	template<typename _Tp>
	concept _Std_pair = __is_pair<_Tp>::value;
	#endif

	// This is a temporary workaround until -fconcepts is implied by -std=gnu++2a
	#if __cpp_concepts
	# define _GLIBCXX_STD_PAIR_CONSTRAINT(T) _Std_pair T
	# define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) _Std_pair T
	#else
	# define _GLIBCXX_STD_PAIR_CONSTRAINT(T) \
	typename T, typename __ = _Require<__is_pair<T>>
	# define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) typename T, typename
	#endif

	template<typename _Tp,
	#if ! __cpp_concepts
	typename __ = _Require<__not_<__is_pair<_Tp>>>,
	#endif
	typename _Alloc, typename... _Args>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a,
	_Args&&... __args) noexcept
	#if __cpp_concepts
	requires (! _Std_pair<_Tp>)
	#endif
	{
	return std::__uses_alloc_args<_Tp>(__a, std::forward<_Args>(__args)...);
	}

	template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
	typename _Tuple1, typename _Tuple2>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
	_Tuple1&& __x, _Tuple2&& __y) noexcept;

	template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc>
	constexpr auto
	uses_allocator_construction_args(const _Alloc&) noexcept;

	template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
	typename _Up, typename _Vp>
	constexpr auto
	uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;

	template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
	typename _Up, typename _Vp>
	constexpr auto
	uses_allocator_construction_args(const _Alloc&,
	const pair<_Up, _Vp>&) noexcept;

	template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
	typename _Up, typename _Vp>
	constexpr auto
	uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;

	template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
	typename _Tuple1, typename _Tuple2>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
	_Tuple1&& __x, _Tuple2&& __y) noexcept
	{
	using _Tp1 = typename _Tp::first_type;
	using _Tp2 = typename _Tp::second_type;

	return std::make_tuple(piecewise_construct,
	std::apply([&__a](auto&&... __args1) {
	return std::uses_allocator_construction_args<_Tp1>(
	__a, std::forward<decltype(__args1)>(__args1)...);
	}, std::forward<_Tuple1>(__x)),
	std::apply([&__a](auto&&... __args2) {
	return std::uses_allocator_construction_args<_Tp2>(
	__a, std::forward<decltype(__args2)>(__args2)...);
	}, std::forward<_Tuple2>(__y)));
	}

	template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a) noexcept
	{
	using _Tp1 = typename _Tp::first_type;
	using _Tp2 = typename _Tp::second_type;

	return std::make_tuple(piecewise_construct,
	std::uses_allocator_construction_args<_Tp1>(__a),
	std::uses_allocator_construction_args<_Tp2>(__a));
	}

	template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
	typename _Up, typename _Vp>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
	noexcept
	{
	using _Tp1 = typename _Tp::first_type;
	using _Tp2 = typename _Tp::second_type;

	return std::make_tuple(piecewise_construct,
	std::uses_allocator_construction_args<_Tp1>(__a,
	std::forward<_Up>(__u)),
	std::uses_allocator_construction_args<_Tp2>(__a,
	std::forward<_Vp>(__v)));
	}

	template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
	typename _Up, typename _Vp>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a,
	const pair<_Up, _Vp>& __pr) noexcept
	{
	using _Tp1 = typename _Tp::first_type;
	using _Tp2 = typename _Tp::second_type;

	return std::make_tuple(piecewise_construct,
	std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
	std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
	}

	template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
	typename _Up, typename _Vp>
	constexpr auto
	uses_allocator_construction_args(const _Alloc& __a,
	pair<_Up, _Vp>&& __pr) noexcept
	{
	using _Tp1 = typename _Tp::first_type;
	using _Tp2 = typename _Tp::second_type;

	return std::make_tuple(piecewise_construct,
	std::uses_allocator_construction_args<_Tp1>(__a,
	std::move(__pr).first),
	std::uses_allocator_construction_args<_Tp2>(__a,
	std::move(__pr).second));
	}

	template<typename _Tp, typename _Alloc, typename... _Args>
	inline _Tp
	make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
	{
	return std::make_from_tuple<_Tp>(
	std::uses_allocator_construction_args<_Tp>(__a,
	std::forward<_Args>(__args)...));
	}

	template<typename _Tp, typename _Alloc, typename... _Args>
	inline _Tp*
	uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
	_Args&&... __args)
	{
	return std::apply([&](auto&&... __xs) {
	return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
	}, std::uses_allocator_construction_args<_Tp>(__a,
	std::forward<_Args>(__args)...));
	}
	// @}

	#endif // C++2a

	_GLIBCXX_END_NAMESPACE_VERSION
	} // namespace
	#endif // C++11

	#if __cplusplus > 201402L
	// Parallel STL algorithms
	# if _PSTL_EXECUTION_POLICIES_DEFINED
	// If <execution> has already been included, pull in implementations
	# include <pstl/glue_memory_impl.h>
	# else
	// Otherwise just pull in forward declarations
	# include <pstl/glue_memory_defs.h>
	# endif

	// Feature test macro for parallel algorithms
	# define __cpp_lib_parallel_algorithm 201603L
	#endif // C++17

	#endif /* _GLIBCXX_MEMORY */