ydb/contrib/libs/cxxsupp/libcxx/include/__utility/declval.h

//===----------------------------------------------------------------------===//
//
// 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