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     ASSERT_SAME_TYPE(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     ASSERT_SAME_TYPE(decltype(opt), std::optional<A>);
37     assert(static_cast<bool>(opt));
38     }
39 
40     {
41 //  optional(const T&);
42     const int& source = 5;
43     std::optional opt(source);
44     ASSERT_SAME_TYPE(decltype(opt), std::optional<int>);
45     assert(static_cast<bool>(opt));
46     assert(*opt == 5);
47     }
48 
49     {
50 //  optional(T*);
51     const int* source = nullptr;
52     std::optional opt(source);
53     ASSERT_SAME_TYPE(decltype(opt), std::optional<const int*>);
54     assert(static_cast<bool>(opt));
55     assert(*opt == nullptr);
56     }
57 
58     {
59 //  optional(T[]);
60     int source[] = {1, 2, 3};
61     std::optional opt(source);
62     ASSERT_SAME_TYPE(decltype(opt), std::optional<int*>);
63     assert(static_cast<bool>(opt));
64     assert((*opt)[0] == 1);
65     }
66 
67 //  Test the implicit deduction guides
68     {
69 //  optional(optional);
70     std::optional<char> source('A');
71     std::optional opt(source);
72     ASSERT_SAME_TYPE(decltype(opt), std::optional<char>);
73     assert(static_cast<bool>(opt) == static_cast<bool>(source));
74     assert(*opt == *source);
75     }
76 
77   return 0;
78 }
79