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c0cde79e9e
As explained in the release note, libc++ used to provide various global variables as an extension in C++03 mode. Unfortunately, that made our definition non-conforming in all standard modes. This was never a big problem until recently, since we are trying to support C++20 Modules in libc++, and that requires cleaning up the definition of these variables. This change is the first in a series of changes to achieve our end goal. This patch removes the ability for users to rely on the (incorrect) definition of those global variables inside the shared library. The plan is to then remove those definitions from the shared library (which is an ABI break but I don't think it will have impact), and finally to make our definition of those variables conforming in all standard modes. Differential Revision: https://reviews.llvm.org/D145422
121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP_EXPERIMENTAL___MEMORY
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#define _LIBCPP_EXPERIMENTAL___MEMORY
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#include <__memory/allocator_arg_t.h>
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#include <__memory/uses_allocator.h>
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#include <__type_traits/conditional.h>
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#include <__type_traits/is_constructible.h>
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#include <__type_traits/is_convertible.h>
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#include <__type_traits/is_same.h>
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#include <experimental/__config>
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#include <experimental/utility> // for erased_type
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_LFTS
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template <
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class _Tp, class _Alloc
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, bool = uses_allocator<_Tp, _Alloc>::value
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, bool = __has_allocator_type<_Tp>::value
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>
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struct __lfts_uses_allocator : public false_type {};
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template <class _Tp, class _Alloc>
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struct __lfts_uses_allocator<_Tp, _Alloc, false, false> : public false_type {};
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template <class _Tp, class _Alloc, bool HasAlloc>
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struct __lfts_uses_allocator<_Tp, _Alloc, true, HasAlloc> : public true_type {};
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template <class _Tp, class _Alloc>
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struct __lfts_uses_allocator<_Tp, _Alloc, false, true>
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: public integral_constant<bool
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, is_convertible<_Alloc, typename _Tp::allocator_type>::value
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|| is_same<erased_type, typename _Tp::allocator_type>::value
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>
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{};
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template <bool _UsesAlloc, class _Tp, class _Alloc, class ..._Args>
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struct __lfts_uses_alloc_ctor_imp
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{
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static const int value = 0;
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};
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template <class _Tp, class _Alloc, class ..._Args>
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struct __lfts_uses_alloc_ctor_imp<true, _Tp, _Alloc, _Args...>
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{
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static const bool __ic_first
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= is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value;
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static const bool __ic_second =
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__conditional_t<
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__ic_first,
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false_type,
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is_constructible<_Tp, _Args..., _Alloc>
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>::value;
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static_assert(__ic_first || __ic_second,
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"Request for uses allocator construction is ill-formed");
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static const int value = __ic_first ? 1 : 2;
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};
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template <class _Tp, class _Alloc, class ..._Args>
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struct __lfts_uses_alloc_ctor
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: integral_constant<int,
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__lfts_uses_alloc_ctor_imp<
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__lfts_uses_allocator<_Tp, _Alloc>::value
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, _Tp, _Alloc, _Args...
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>::value
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>
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{};
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template <class _Tp, class _Allocator, class... _Args>
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inline _LIBCPP_INLINE_VISIBILITY
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void __user_alloc_construct_impl (integral_constant<int, 0>, _Tp *__storage, const _Allocator &, _Args &&... __args )
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{
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new (__storage) _Tp (_VSTD::forward<_Args>(__args)...);
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}
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// FIXME: This should have a version which takes a non-const alloc.
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template <class _Tp, class _Allocator, class... _Args>
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inline _LIBCPP_INLINE_VISIBILITY
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void __user_alloc_construct_impl (integral_constant<int, 1>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
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{
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new (__storage) _Tp (allocator_arg_t(), __a, _VSTD::forward<_Args>(__args)...);
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}
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// FIXME: This should have a version which takes a non-const alloc.
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template <class _Tp, class _Allocator, class... _Args>
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inline _LIBCPP_INLINE_VISIBILITY
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void __user_alloc_construct_impl (integral_constant<int, 2>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
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{
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new (__storage) _Tp (_VSTD::forward<_Args>(__args)..., __a);
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}
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template <class _Tp, class _Alloc, class ..._Args>
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inline _LIBCPP_INLINE_VISIBILITY
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void __lfts_user_alloc_construct(
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_Tp * __store, const _Alloc & __a, _Args &&... __args)
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{
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::std::experimental::fundamentals_v1::__user_alloc_construct_impl(
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typename __lfts_uses_alloc_ctor<_Tp, _Alloc, _Args...>::type()
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, __store, __a, _VSTD::forward<_Args>(__args)...
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);
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}
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_LIBCPP_END_NAMESPACE_LFTS
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#endif /* _LIBCPP_EXPERIMENTAL___MEMORY */
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