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
21template <class _Tp, bool = is_enum<_Tp>::value> struct __underlying_type_impl;
22
23template <class _Tp>
24struct __underlying_type_impl<_Tp, false> {};
25
26template <class _Tp>
27struct __underlying_type_impl<_Tp, true>
28{
29    typedef __underlying_type(_Tp) type;
30};
31
32template <class _Tp>
33struct underlying_type : __underlying_type_impl<_Tp, is_enum<_Tp>::value> {};
34
35#if _LIBCPP_STD_VER > 11
36template <class _Tp> using underlying_type_t = typename underlying_type<_Tp>::type;
37#endif
38
39_LIBCPP_END_NAMESPACE_STD
40
41#endif // _LIBCPP___TYPE_TRAITS_UNDERLYING_TYPE_H
42