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___TYPE_TRAITS_UNDERLYING_TYPE_H
10 #define _LIBCPP___TYPE_TRAITS_UNDERLYING_TYPE_H
11 
12 #include <__config>
13 #include <__type_traits/is_enum.h>
14 
15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16 #  pragma GCC system_header
17 #endif
18 
19 _LIBCPP_BEGIN_NAMESPACE_STD
20 
21 template <class _Tp, bool = is_enum<_Tp>::value>
22 struct __underlying_type_impl;
23 
24 template <class _Tp>
25 struct __underlying_type_impl<_Tp, false> {};
26 
27 template <class _Tp>
28 struct __underlying_type_impl<_Tp, true> {
29   typedef __underlying_type(_Tp) type;
30 };
31 
32 template <class _Tp>
33 struct underlying_type : __underlying_type_impl<_Tp, is_enum<_Tp>::value> {};
34 
35 #if _LIBCPP_STD_VER >= 14
36 template <class _Tp>
37 using underlying_type_t = typename underlying_type<_Tp>::type;
38 #endif
39 
40 _LIBCPP_END_NAMESPACE_STD
41 
42 #endif // _LIBCPP___TYPE_TRAITS_UNDERLYING_TYPE_H
43