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_IS_SAME_H
10 #define _LIBCPP___TYPE_TRAITS_IS_SAME_H
11 
12 #include <__config>
13 #include <__type_traits/integral_constant.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, class _Up>
22 struct _LIBCPP_TEMPLATE_VIS is_same : _BoolConstant<__is_same(_Tp, _Up)> {};
23 
24 #if _LIBCPP_STD_VER >= 17
25 template <class _Tp, class _Up>
26 inline constexpr bool is_same_v = __is_same(_Tp, _Up);
27 #endif
28 
29 // _IsSame<T,U> has the same effect as is_same<T,U> but instantiates fewer types:
30 // is_same<A,B> and is_same<C,D> are guaranteed to be different types, but
31 // _IsSame<A,B> and _IsSame<C,D> are the same type (namely, false_type).
32 // Neither GCC nor Clang can mangle the __is_same builtin, so _IsSame
33 // mustn't be directly used anywhere that contributes to name-mangling
34 // (such as in a dependent return type).
35 
36 template <class _Tp, class _Up>
37 using _IsSame = _BoolConstant<__is_same(_Tp, _Up)>;
38 
39 template <class _Tp, class _Up>
40 using _IsNotSame = _BoolConstant<!__is_same(_Tp, _Up)>;
41 
42 _LIBCPP_END_NAMESPACE_STD
43 
44 #endif // _LIBCPP___TYPE_TRAITS_IS_SAME_H
45