__cxx03/__utility/as_const.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CXX03___UTILITY_AS_CONST_H
0010 #define _LIBCPP___CXX03___UTILITY_AS_CONST_H
0011
0012 #include <__cxx03/__config>
0013 #include <__cxx03/__type_traits/add_const.h>
0014 #include <__cxx03/__utility/forward.h>
0015 #include <__cxx03/__utility/move.h>
0016
0017 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0018 #  pragma GCC system_header
0019 #endif
0020
0021 _LIBCPP_BEGIN_NAMESPACE_STD
0022
0023 #if _LIBCPP_STD_VER >= 17
0024 template <class _Tp>
0025 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept {
0026   return __t;
0027 }
0028
0029 template <class _Tp>
0030 void as_const(const _Tp&&) = delete;
0031 #endif
0032
0033 _LIBCPP_END_NAMESPACE_STD
0034
0035 #endif // _LIBCPP___CXX03___UTILITY_AS_CONST_H