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- //===----------------------------------------------------------------------===//
- //
- // 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___UTILITY_DECLVAL_H
- #define _LIBCPP___UTILITY_DECLVAL_H
- #include <__config>
- #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
- # pragma GCC system_header
- #endif
- _LIBCPP_BEGIN_NAMESPACE_STD
- // Suppress deprecation notice for volatile-qualified return type resulting
- // from volatile-qualified types _Tp.
- _LIBCPP_SUPPRESS_DEPRECATED_PUSH
- template <class _Tp>
- _Tp&& __declval(int);
- template <class _Tp>
- _Tp __declval(long);
- _LIBCPP_SUPPRESS_DEPRECATED_POP
- #ifdef _LIBCPP_COMPILER_MSVC
- template <class _Tp>
- using __declval_void = void;
- template <class _Tp, class = void>
- struct __declval_add_rvalue_reference {
- using type = _Tp;
- };
- template <class _Tp>
- struct __declval_add_rvalue_reference<_Tp, __declval_void<_Tp&>> {
- using type = _Tp&&;
- };
- #endif
- template <class _Tp>
- #ifdef _LIBCPP_COMPILER_MSVC
- typename __declval_add_rvalue_reference<_Tp>::type
- #else
- decltype(__declval<_Tp>(0))
- #endif
- declval() _NOEXCEPT;
- _LIBCPP_END_NAMESPACE_STD
- #endif // _LIBCPP___UTILITY_DECLVAL_H
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