libcxx/include/__utility/to_underlying.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___UTILITY_TO_UNDERLYING_H
  11 #define _LIBCPP___UTILITY_TO_UNDERLYING_H
  12
  13 #include <__config>
  14 #include <__type_traits/underlying_type.h>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_BEGIN_NAMESPACE_STD
  21
  22 #ifndef _LIBCPP_CXX03_LANG
  23 template <class _Tp>
  24 _LIBCPP_HIDE_FROM_ABI constexpr typename underlying_type<_Tp>::type __to_underlying(_Tp __val) noexcept {
  25   return static_cast<typename underlying_type<_Tp>::type>(__val);
  26 }
  27 #endif // !_LIBCPP_CXX03_LANG
  28
  29 #if _LIBCPP_STD_VER >= 23
  30 template <class _Tp>
  31 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr underlying_type_t<_Tp> to_underlying(_Tp __val) noexcept {
  32   return std::__to_underlying(__val);
  33 }
  34 #endif
  35
  36 _LIBCPP_END_NAMESPACE_STD
  37
  38 #endif // _LIBCPP___UTILITY_TO_UNDERLYING_H