|  | //===----------------------------------------------------------------------===// | 
|  | // | 
|  | // 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_AS_CONST_H | 
|  | #define _LIBCPP___UTILITY_AS_CONST_H | 
|  |  | 
|  | #include <__config> | 
|  | #include <__type_traits/add_const.h> | 
|  | #include <__utility/forward.h> | 
|  | #include <__utility/move.h> | 
|  |  | 
|  | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) | 
|  | #  pragma GCC system_header | 
|  | #endif | 
|  |  | 
|  | _LIBCPP_BEGIN_NAMESPACE_STD | 
|  |  | 
|  | #if _LIBCPP_STD_VER >= 17 | 
|  | template <class _Tp> | 
|  | [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { | 
|  | return __t; | 
|  | } | 
|  |  | 
|  | template <class _Tp> | 
|  | void as_const(const _Tp&&) = delete; | 
|  | #endif | 
|  |  | 
|  | _LIBCPP_END_NAMESPACE_STD | 
|  |  | 
|  | #endif // _LIBCPP___UTILITY_AS_CONST_H |