libcxx/include/__utility/as_const.h

   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
  14 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  15 #  pragma GCC system_header
  16 #endif
  17
  18 _LIBCPP_BEGIN_NAMESPACE_STD
  19
  20 #if _LIBCPP_STD_VER >= 17
  21 template <class _Tp>
  22 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& as_const(_Tp& __t) noexcept {
  23   return __t;
  24 }
  25
  26 template <class _Tp>
  27 void as_const(const _Tp&&) = delete;
  28 #endif
  29
  30 _LIBCPP_END_NAMESPACE_STD
  31
  32 #endif // _LIBCPP___UTILITY_AS_CONST_H