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 // <optional>
10 // UNSUPPORTED: c++03, c++11, c++14
11 
12 // template<class T>
13 //   optional(T) -> optional<T>;
14 
15 #include <optional>
16 #include <cassert>
17 
18 #include "test_macros.h"
19 
20 struct A {};
21 
22 int main(int, char**)
23 {
24 //  Test the explicit deduction guides
25     {
26 //  optional(T)
27     std::optional opt(5);
28     static_assert(std::is_same_v<decltype(opt), std::optional<int>>, "");
29     assert(static_cast<bool>(opt));
30     assert(*opt == 5);
31     }
32 
33     {
34 //  optional(T)
35     std::optional opt(A{});
36     static_assert(std::is_same_v<decltype(opt), std::optional<A>>, "");
37     assert(static_cast<bool>(opt));
38     }
39 
40 //  Test the implicit deduction guides
41     {
42 //  optional(optional);
43     std::optional<char> source('A');
44     std::optional opt(source);
45     static_assert(std::is_same_v<decltype(opt), std::optional<char>>, "");
46     assert(static_cast<bool>(opt) == static_cast<bool>(source));
47     assert(*opt == *source);
48     }
49 
50   return 0;
51 }
52