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, c++14
10
11// <optional>
12
13// constexpr const T& optional<T>::value() const &;
14
15#include <optional>
16#include <type_traits>
17#include <cassert>
18
19#include "test_macros.h"
20
21using std::optional;
22using std::in_place_t;
23using std::in_place;
24using std::bad_optional_access;
25
26struct X
27{
28 X() = default;
29 X(const X&) = delete;
30 constexpr int test() const & {return 3;}
31 int test() & {return 4;}
32 constexpr int test() const && {return 5;}
33 int test() && {return 6;}
34};
35
36int main(int, char**)
37{
38 {
39 const optional<X> opt; ((void)opt);
40 ASSERT_NOT_NOEXCEPT(opt.value());
41 ASSERT_SAME_TYPE(decltype(opt.value()), X const&);
42 }
43 {
44 constexpr optional<X> opt(in_place);
45 static_assert(opt.value().test() == 3, "");
46 }
47 {
48 const optional<X> opt(in_place);
49 assert(opt.value().test() == 3);
50 }
51#ifndef TEST_HAS_NO_EXCEPTIONS
52 {
53 const optional<X> opt;
54 try
55 {
56 (void)opt.value();
57 assert(false);
58 }
59 catch (const bad_optional_access&)
60 {
61 }
62 }
63#endif
64
65 return 0;
66}
67

source code of libcxx/test/std/utilities/optional/optional.object/optional.object.observe/value_const.pass.cpp