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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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