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, c++17, c++20
10
11// template<class U = T>
12// constexpr explicit(!is_convertible_v<U, T>) expected(U&& v);
13//
14// Constraints:
15// - is_same_v<remove_cvref_t<U>, in_place_t> is false; and
16// - is_same_v<expected, remove_cvref_t<U>> is false; and
17// - remove_cvref_t<U> is not a specialization of unexpected; and
18// - is_constructible_v<T, U> is true.
19//
20// Effects: Direct-non-list-initializes val with std::forward<U>(v).
21//
22// Postconditions: has_value() is true.
23//
24// Throws: Any exception thrown by the initialization of val.
25
26#include <cassert>
27#include <expected>
28#include <type_traits>
29#include <utility>
30
31#include "MoveOnly.h"
32#include "test_macros.h"
33#include "../../types.h"
34
35// Test Constraints:
36static_assert(std::is_constructible_v<std::expected<int, int>, int>);
37
38// is_same_v<remove_cvref_t<U>, in_place_t>
39struct FromJustInplace {
40 FromJustInplace(std::in_place_t);
41};
42static_assert(!std::is_constructible_v<std::expected<FromJustInplace, int>, std::in_place_t>);
43static_assert(!std::is_constructible_v<std::expected<FromJustInplace, int>, std::in_place_t const&>);
44
45// is_same_v<expected, remove_cvref_t<U>>
46// Note that result is true because it is covered by the constructors that take expected
47static_assert(std::is_constructible_v<std::expected<int, int>, std::expected<int, int>&>);
48
49// remove_cvref_t<U> is a specialization of unexpected
50// Note that result is true because it is covered by the constructors that take unexpected
51static_assert(std::is_constructible_v<std::expected<int, int>, std::unexpected<int>&>);
52
53// !is_constructible_v<T, U>
54struct foo {};
55static_assert(!std::is_constructible_v<std::expected<int, int>, foo>);
56
57// test explicit(!is_convertible_v<U, T>)
58struct NotConvertible {
59 explicit NotConvertible(int);
60};
61static_assert(std::is_convertible_v<int, std::expected<int, int>>);
62static_assert(!std::is_convertible_v<int, std::expected<NotConvertible, int>>);
63
64struct CopyOnly {
65 int i;
66 constexpr CopyOnly(int ii) : i(ii) {}
67 CopyOnly(const CopyOnly&) = default;
68 CopyOnly(CopyOnly&&) = delete;
69 friend constexpr bool operator==(const CopyOnly& mi, int ii) { return mi.i == ii; }
70};
71
72struct BaseError {};
73struct DerivedError : BaseError {};
74
75template <class T, class E = int>
76constexpr void testInt() {
77 std::expected<T, E> e(5);
78 assert(e.has_value());
79 assert(e.value() == 5);
80}
81
82template <class T, class E = int>
83constexpr void testLValue() {
84 T t(5);
85 std::expected<T, E> e(t);
86 assert(e.has_value());
87 assert(e.value() == 5);
88}
89
90template <class T, class E = int>
91constexpr void testRValue() {
92 std::expected<T, E> e(T(5));
93 assert(e.has_value());
94 assert(e.value() == 5);
95}
96
97constexpr bool test() {
98 testInt<int>();
99 testInt<CopyOnly>();
100 testInt<MoveOnly>();
101 testInt<TailClobberer<0>, bool>();
102 testLValue<int>();
103 testLValue<CopyOnly>();
104 testLValue<TailClobberer<0>, bool>();
105 testRValue<int>();
106 testRValue<MoveOnly>();
107 testRValue<TailClobberer<0>, bool>();
108
109 // Test default template argument.
110 // Without it, the template parameter cannot be deduced from an initializer list
111 {
112 struct Bar {
113 int i;
114 int j;
115 constexpr Bar(int ii, int jj) : i(ii), j(jj) {}
116 };
117
118 std::expected<Bar, int> e({5, 6});
119 assert(e.value().i == 5);
120 assert(e.value().j == 6);
121 }
122
123 // https://cplusplus.github.io/LWG/issue3836
124
125 // Test &
126 {
127 std::expected<bool, DerivedError> e1(false);
128 std::expected<bool, BaseError> e2(e1);
129 assert(e2.has_value());
130 assert(!e2.value()); // yes, e2 holds "false" since LWG3836
131 }
132
133 // Test &&
134 {
135 std::expected<bool, DerivedError> e1(false);
136 std::expected<bool, BaseError> e2(std::move(e1));
137 assert(e2.has_value());
138 assert(!e2.value()); // yes, e2 holds "false" since LWG3836
139 }
140
141 // Test const&
142 {
143 const std::expected<bool, DerivedError> e1(false);
144 std::expected<bool, BaseError> e2(e1);
145 assert(e2.has_value());
146 assert(!e2.value()); // yes, e2 holds "false" since LWG3836
147 }
148
149 // Test const&&
150 {
151 const std::expected<bool, DerivedError> e1(false);
152 std::expected<bool, BaseError> e2(std::move(e1));
153 assert(e2.has_value());
154 assert(!e2.value()); // yes, e2 holds "false" since LWG3836
155 }
156 return true;
157}
158
159void testException() {
160#ifndef TEST_HAS_NO_EXCEPTIONS
161 struct Throwing {
162 Throwing(int) { throw Except{}; };
163 };
164
165 try {
166 std::expected<Throwing, int> u(5);
167 assert(false);
168 } catch (Except) {
169 }
170#endif // TEST_HAS_NO_EXCEPTIONS
171}
172
173int main(int, char**) {
174 test();
175 static_assert(test());
176 testException();
177 return 0;
178}
179

source code of libcxx/test/std/utilities/expected/expected.expected/ctor/ctor.u.pass.cpp