xref: /llvm-project/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_or.pass.cpp (revision 31cbe0f240f660f15602c96b787c58a26f17e179)
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 // UNSUPPORTED: c++03, c++11
10 // <experimental/type_traits>
11 
12 #include <experimental/type_traits>
13 #include <string>
14 
15 #include "test_macros.h"
16 
17 namespace ex = std::experimental;
18 
19 template <typename T>
20   using hasFoo = typename T::Foo;
21 
22 struct yesFoo {
23     using Foo = int;
24 };
25 
26 struct noFoo {
27 };
28 
29 
30 template <typename T, typename Res>
test()31 void test() {
32     static_assert( std::is_same<Res, typename ex::detected_or  <double, hasFoo, T>::type>::value, "" );
33     static_assert( std::is_same<Res, typename ex::detected_or_t<double, hasFoo, T>      >::value, "" );
34 }
35 
main(int,char **)36 int main(int, char**) {
37     test<yesFoo, int>();
38     test<noFoo, double>();
39 
40   return 0;
41 }
42