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

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