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268 lines
8.6 KiB
268 lines
8.6 KiB
// nonstandard construct and destroy functions -*- C++ -*-
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// Copyright (C) 2001-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/*
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*
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* Copyright (c) 1994
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* Hewlett-Packard Company
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Hewlett-Packard Company makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*
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* Copyright (c) 1996,1997
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file bits/stl_construct.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{memory}
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*/
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#ifndef _STL_CONSTRUCT_H
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#define _STL_CONSTRUCT_H 1
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#include <new>
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#include <bits/move.h>
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#include <bits/stl_iterator_base_types.h> // for iterator_traits
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#include <bits/stl_iterator_base_funcs.h> // for advance
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/* This file provides the C++17 functions std::destroy_at, std::destroy, and
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* std::destroy_n, and the C++20 function std::construct_at.
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* It also provides std::_Construct, std::_Destroy,and std::_Destroy_n functions
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* which are defined in all standard modes and so can be used in C++98-14 code.
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* The _Destroy functions will dispatch to destroy_at during constant
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* evaluation, because calls to that function are intercepted by the compiler
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* to allow use in constant expressions.
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*/
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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#if __cplusplus >= 201703L
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template <typename _Tp>
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_GLIBCXX20_CONSTEXPR inline void
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destroy_at(_Tp* __location)
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{
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if constexpr (__cplusplus > 201703L && is_array_v<_Tp>)
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{
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for (auto& __x : *__location)
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std::destroy_at(std::__addressof(__x));
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}
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else
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__location->~_Tp();
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}
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#if __cplusplus >= 202002L
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template<typename _Tp, typename... _Args>
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constexpr auto
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construct_at(_Tp* __location, _Args&&... __args)
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noexcept(noexcept(::new((void*)0) _Tp(std::declval<_Args>()...)))
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-> decltype(::new((void*)0) _Tp(std::declval<_Args>()...))
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{ return ::new((void*)__location) _Tp(std::forward<_Args>(__args)...); }
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#endif // C++20
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#endif// C++17
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/**
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* Constructs an object in existing memory by invoking an allocated
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* object's constructor with an initializer.
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*/
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#if __cplusplus >= 201103L
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template<typename _Tp, typename... _Args>
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_GLIBCXX20_CONSTEXPR
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inline void
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_Construct(_Tp* __p, _Args&&... __args)
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{
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#if __cplusplus >= 202002L && __has_builtin(__builtin_is_constant_evaluated)
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if (__builtin_is_constant_evaluated())
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{
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// Allow std::_Construct to be used in constant expressions.
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std::construct_at(__p, std::forward<_Args>(__args)...);
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return;
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}
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#endif
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::new((void*)__p) _Tp(std::forward<_Args>(__args)...);
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}
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#else
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template<typename _T1, typename _T2>
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inline void
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_Construct(_T1* __p, const _T2& __value)
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{
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 402. wrong new expression in [some_]allocator::construct
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::new(static_cast<void*>(__p)) _T1(__value);
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}
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#endif
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template<typename _T1>
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inline void
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_Construct_novalue(_T1* __p)
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{ ::new((void*)__p) _T1; }
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template<typename _ForwardIterator>
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_GLIBCXX20_CONSTEXPR void
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_Destroy(_ForwardIterator __first, _ForwardIterator __last);
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/**
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* Destroy the object pointed to by a pointer type.
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*/
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template<typename _Tp>
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_GLIBCXX14_CONSTEXPR inline void
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_Destroy(_Tp* __pointer)
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{
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#if __cplusplus > 201703L
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std::destroy_at(__pointer);
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#else
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__pointer->~_Tp();
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#endif
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}
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template<bool>
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struct _Destroy_aux
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{
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template<typename _ForwardIterator>
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static _GLIBCXX20_CONSTEXPR void
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__destroy(_ForwardIterator __first, _ForwardIterator __last)
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{
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for (; __first != __last; ++__first)
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std::_Destroy(std::__addressof(*__first));
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}
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};
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template<>
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struct _Destroy_aux<true>
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{
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template<typename _ForwardIterator>
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static void
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__destroy(_ForwardIterator, _ForwardIterator) { }
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};
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/**
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* Destroy a range of objects. If the value_type of the object has
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* a trivial destructor, the compiler should optimize all of this
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* away, otherwise the objects' destructors must be invoked.
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*/
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template<typename _ForwardIterator>
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_GLIBCXX20_CONSTEXPR inline void
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_Destroy(_ForwardIterator __first, _ForwardIterator __last)
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{
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typedef typename iterator_traits<_ForwardIterator>::value_type
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_Value_type;
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#if __cplusplus >= 201103L
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// A deleted destructor is trivial, this ensures we reject such types:
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static_assert(is_destructible<_Value_type>::value,
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"value type is destructible");
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#endif
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#if __cplusplus > 201703L && defined __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return _Destroy_aux<false>::__destroy(__first, __last);
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#endif
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std::_Destroy_aux<__has_trivial_destructor(_Value_type)>::
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__destroy(__first, __last);
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}
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template<bool>
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struct _Destroy_n_aux
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{
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template<typename _ForwardIterator, typename _Size>
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static _GLIBCXX20_CONSTEXPR _ForwardIterator
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__destroy_n(_ForwardIterator __first, _Size __count)
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{
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for (; __count > 0; (void)++__first, --__count)
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std::_Destroy(std::__addressof(*__first));
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return __first;
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}
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};
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template<>
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struct _Destroy_n_aux<true>
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{
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template<typename _ForwardIterator, typename _Size>
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static _ForwardIterator
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__destroy_n(_ForwardIterator __first, _Size __count)
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{
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std::advance(__first, __count);
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return __first;
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}
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};
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/**
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* Destroy a range of objects. If the value_type of the object has
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* a trivial destructor, the compiler should optimize all of this
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* away, otherwise the objects' destructors must be invoked.
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*/
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template<typename _ForwardIterator, typename _Size>
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_GLIBCXX20_CONSTEXPR inline _ForwardIterator
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_Destroy_n(_ForwardIterator __first, _Size __count)
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{
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typedef typename iterator_traits<_ForwardIterator>::value_type
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_Value_type;
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#if __cplusplus >= 201103L
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// A deleted destructor is trivial, this ensures we reject such types:
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static_assert(is_destructible<_Value_type>::value,
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"value type is destructible");
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#endif
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#if __cplusplus > 201703L && defined __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return _Destroy_n_aux<false>::__destroy_n(__first, __count);
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#endif
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return std::_Destroy_n_aux<__has_trivial_destructor(_Value_type)>::
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__destroy_n(__first, __count);
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}
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#if __cplusplus >= 201703L
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template <typename _ForwardIterator>
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_GLIBCXX20_CONSTEXPR inline void
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destroy(_ForwardIterator __first, _ForwardIterator __last)
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{
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std::_Destroy(__first, __last);
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}
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template <typename _ForwardIterator, typename _Size>
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_GLIBCXX20_CONSTEXPR inline _ForwardIterator
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destroy_n(_ForwardIterator __first, _Size __count)
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{
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return std::_Destroy_n(__first, __count);
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}
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#endif // C++17
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif /* _STL_CONSTRUCT_H */
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