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
20struct A {};
21
22int 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

source code of libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/deduct.pass.cpp