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 // UNSUPPORTED: clang-5, apple-clang-9
12 // UNSUPPORTED: libcpp-no-deduction-guides
13 // Clang 5 will generate bad implicit deduction guides
14 // Specifically, for the copy constructor.
15
16
17 // template<class T>
18 // optional(T) -> optional<T>;
19
20
21 #include <optional>
22 #include <cassert>
23
24 #include "test_macros.h"
25
26 struct A {};
27
main(int,char **)28 int main(int, char**)
29 {
30 // Test the explicit deduction guides
31 {
32 // optional(T)
33 std::optional opt(5);
34 static_assert(std::is_same_v<decltype(opt), std::optional<int>>, "");
35 assert(static_cast<bool>(opt));
36 assert(*opt == 5);
37 }
38
39 {
40 // optional(T)
41 std::optional opt(A{});
42 static_assert(std::is_same_v<decltype(opt), std::optional<A>>, "");
43 assert(static_cast<bool>(opt));
44 }
45
46 // Test the implicit deduction guides
47 {
48 // optional(optional);
49 std::optional<char> source('A');
50 std::optional opt(source);
51 static_assert(std::is_same_v<decltype(opt), std::optional<char>>, "");
52 assert(static_cast<bool>(opt) == static_cast<bool>(source));
53 assert(*opt == *source);
54 }
55
56 return 0;
57 }
58