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_VALID_EXPANSION_H
10 #define _LIBCPP___TYPE_TRAITS_IS_VALID_EXPANSION_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 <template <class...> class _Templ, class... _Args, class = _Templ<_Args...> >
22 true_type __sfinae_test_impl(int);
23 template <template <class...> class, class...>
24 false_type __sfinae_test_impl(...);
25 
26 template <template <class...> class _Templ, class... _Args>
27 using _IsValidExpansion _LIBCPP_NODEBUG = decltype(std::__sfinae_test_impl<_Templ, _Args...>(0));
28 
29 _LIBCPP_END_NAMESPACE_STD
30 
31 #endif // _LIBCPP___TYPE_TRAITS_IS_VALID_EXPANSION_H
32