1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___UTILITY_AS_CONST_H 10 #define _LIBCPP___UTILITY_AS_CONST_H 11 12 #include <__config> 13 #include <__type_traits/add_const.h> 14 #include <__utility/forward.h> 15 #include <__utility/move.h> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_BEGIN_NAMESPACE_STD 22 23 #if _LIBCPP_STD_VER >= 17 24 template <class _Tp> 25 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { 26 return __t; 27 } 28 29 template <class _Tp> 30 void as_const(const _Tp&&) = delete; 31 #endif 32 33 _LIBCPP_END_NAMESPACE_STD 34 35 #endif // _LIBCPP___UTILITY_AS_CONST_H 36