1//===----------------------------------------------------------------------===//
2// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3// See https://llvm.org/LICENSE.txt for license information.
4// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5//
6//===----------------------------------------------------------------------===//
7
8// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
9
10// constexpr const T& value() const &;
11// constexpr T& value() &;
12// constexpr T&& value() &&;
13// constexpr const T&& value() const &&;
14
15#include <cassert>
16#include <concepts>
17#include <expected>
18#include <type_traits>
19#include <utility>
20
21#include "test_macros.h"
22
23constexpr bool test() {
24 // non-const &
25 {
26 std::expected<int, int> e(5);
27 decltype(auto) x = e.value();
28 static_assert(std::same_as<decltype(x), int&>);
29 assert(&x == &(*e));
30 assert(x == 5);
31 }
32
33 // const &
34 {
35 const std::expected<int, int> e(5);
36 decltype(auto) x = e.value();
37 static_assert(std::same_as<decltype(x), const int&>);
38 assert(&x == &(*e));
39 assert(x == 5);
40 }
41
42 // non-const &&
43 {
44 std::expected<int, int> e(5);
45 decltype(auto) x = std::move(e).value();
46 static_assert(std::same_as<decltype(x), int&&>);
47 assert(&x == &(*e));
48 assert(x == 5);
49 }
50
51 // const &&
52 {
53 const std::expected<int, int> e(5);
54 decltype(auto) x = std::move(e).value();
55 static_assert(std::same_as<decltype(x), const int&&>);
56 assert(&x == &(*e));
57 assert(x == 5);
58 }
59
60 return true;
61}
62
63void testException() {
64#ifndef TEST_HAS_NO_EXCEPTIONS
65
66 // int
67 {
68 const std::expected<int, int> e(std::unexpect, 5);
69 try {
70 (void) e.value();
71 assert(false);
72 } catch (const std::bad_expected_access<int>& ex) {
73 assert(ex.error() == 5);
74 }
75 }
76
77#endif // TEST_HAS_NO_EXCEPTIONS
78}
79
80void testAsConst() {
81#ifndef TEST_HAS_NO_EXCEPTIONS
82 struct Error {
83 enum { Default, MutableRefCalled, ConstRefCalled } From = Default;
84 Error() = default;
85 Error(const Error&) { From = ConstRefCalled; }
86 Error(Error&) { From = MutableRefCalled; }
87 Error(Error&& e) { From = e.From; }
88 };
89
90 // Test & overload
91 {
92 std::expected<int, Error> e(std::unexpect, Error());
93 try {
94 (void)e.value();
95 assert(false);
96 } catch (const std::bad_expected_access<Error>& ex) {
97 assert(ex.error().From == Error::ConstRefCalled);
98 }
99 }
100
101 // There are no effects for `const &` overload.
102
103#endif // TEST_HAS_NO_EXCEPTIONS
104}
105
106int main(int, char**) {
107 test();
108 static_assert(test());
109 testException();
110 testAsConst();
111
112 return 0;
113}
114

source code of libcxx/test/std/utilities/expected/expected.expected/observers/value.pass.cpp