f599e7a789
This patch fixes the constrains on the __perfect_forward constructor and its call operators, which were incorrect. In particular, it makes sure that we closely follow [func.require], which basically says that we must deliver the bound arguments with the appropriate value category or make the call ill-formed, but not silently fall back to using a different value category. As a fly-by, this patch also: - Adds types __bind_front_t and __not_fn_t to make the result of calling bind_front and not_fn more opaque, and improve diagnostics for users. - Adds a bunch of tests for bind_front and remove some that are now redundant. - Adds some missing _LIBCPP_HIDE_FROM_ABI annotations. Immense thanks to @tcanens for raising awareness about this issue, and providing help with the = delete bits. Differential Revision: https://reviews.llvm.org/D107199
54 lines
1.6 KiB
C++
54 lines
1.6 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___FUNCTIONAL_NOT_FN_H
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#define _LIBCPP___FUNCTIONAL_NOT_FN_H
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#include <__config>
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#include <__functional/perfect_forward.h>
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#include <__functional/invoke.h>
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#include <utility>
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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_STD
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#if _LIBCPP_STD_VER > 14
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struct __not_fn_op {
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template <class... _Args>
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_LIBCPP_HIDE_FROM_ABI
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_LIBCPP_CONSTEXPR_AFTER_CXX17 auto operator()(_Args&&... __args) const
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noexcept(noexcept(!_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
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-> decltype( !_VSTD::invoke(_VSTD::forward<_Args>(__args)...))
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{ return !_VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
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};
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template <class _Fn>
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struct __not_fn_t : __perfect_forward<__not_fn_op, _Fn> {
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using __perfect_forward<__not_fn_op, _Fn>::__perfect_forward;
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};
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template <class _Fn, class = _EnableIf<
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is_constructible_v<decay_t<_Fn>, _Fn> &&
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is_move_constructible_v<decay_t<_Fn>>
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>>
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_LIBCPP_HIDE_FROM_ABI
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_LIBCPP_CONSTEXPR_AFTER_CXX17 auto not_fn(_Fn&& __f) {
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return __not_fn_t<decay_t<_Fn>>(_VSTD::forward<_Fn>(__f));
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}
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#endif // _LIBCPP_STD_VER > 14
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FUNCTIONAL_NOT_FN_H
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