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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