v1/__utility/to_underlying.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___UTILITY_TO_UNDERLYING_H
0011 #define _LIBCPP___UTILITY_TO_UNDERLYING_H
0012
0013 #include <__config>
0014 #include <__type_traits/underlying_type.h>
0015
0016 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0017 #  pragma GCC system_header
0018 #endif
0019
0020 _LIBCPP_BEGIN_NAMESPACE_STD
0021
0022 #ifndef _LIBCPP_CXX03_LANG
0023 template <class _Tp>
0024 _LIBCPP_HIDE_FROM_ABI constexpr typename underlying_type<_Tp>::type __to_underlying(_Tp __val) noexcept {
0025   return static_cast<typename underlying_type<_Tp>::type>(__val);
0026 }
0027 #endif // !_LIBCPP_CXX03_LANG
0028
0029 #if _LIBCPP_STD_VER >= 23
0030 template <class _Tp>
0031 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr underlying_type_t<_Tp> to_underlying(_Tp __val) noexcept {
0032   return std::__to_underlying(__val);
0033 }
0034 #endif
0035
0036 _LIBCPP_END_NAMESPACE_STD
0037
0038 #endif // _LIBCPP___UTILITY_TO_UNDERLYING_H