mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 11:37:35 +00:00
38 lines
1.2 KiB
C++
38 lines
1.2 KiB
C++
//===----------------------------------------------------------------------===//
|
|
//
|
|
// 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
|
|
|
|
template <class _Tp>
|
|
_LIBCPP_HIDE_FROM_ABI decltype(std::__declval<_Tp>(0)) declval() _NOEXCEPT {
|
|
static_assert(!__is_same(_Tp, _Tp),
|
|
"std::declval can only be used in an unevaluated context. "
|
|
"It's likely that your current usage is trying to extract a value from the function.");
|
|
}
|
|
|
|
_LIBCPP_END_NAMESPACE_STD
|
|
|
|
#endif // _LIBCPP___UTILITY_DECLVAL_H
|