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// constexpr expected& operator=(const expected& rhs);
12//
13// Effects:
14// - If this->has_value() && rhs.has_value() is true, equivalent to val = *rhs.
15// - Otherwise, if this->has_value() is true, equivalent to:
16// reinit-expected(unex, val, rhs.error())
17// - Otherwise, if rhs.has_value() is true, equivalent to:
18// reinit-expected(val, unex, *rhs)
19// - Otherwise, equivalent to unex = rhs.error().
20//
21// - Then, if no exception was thrown, equivalent to: has_val = rhs.has_value(); return *this;
22//
23// Returns: *this.
24//
25// Remarks: This operator is defined as deleted unless:
26// - is_copy_assignable_v<T> is true and
27// - is_copy_constructible_v<T> is true and
28// - is_copy_assignable_v<E> is true and
29// - is_copy_constructible_v<E> is true and
30// - is_nothrow_move_constructible_v<T> || is_nothrow_move_constructible_v<E> is true.
31
32#include <cassert>
33#include <concepts>
34#include <expected>
35#include <type_traits>
36#include <utility>
37
38#include "../../types.h"
39#include "test_macros.h"
40
41struct NotCopyConstructible {
42 NotCopyConstructible(const NotCopyConstructible&) = delete;
43 NotCopyConstructible& operator=(const NotCopyConstructible&) = default;
44};
45
46struct NotCopyAssignable {
47 NotCopyAssignable(const NotCopyAssignable&) = default;
48 NotCopyAssignable& operator=(const NotCopyAssignable&) = delete;
49};
50
51struct MoveMayThrow {
52 MoveMayThrow(MoveMayThrow const&) = default;
53 MoveMayThrow& operator=(const MoveMayThrow&) = default;
54 MoveMayThrow(MoveMayThrow&&) noexcept(false) {}
55 MoveMayThrow& operator=(MoveMayThrow&&) noexcept(false) { return *this; }
56};
57
58// Test constraints
59static_assert(std::is_copy_assignable_v<std::expected<int, int>>);
60
61// !is_copy_assignable_v<T>
62static_assert(!std::is_copy_assignable_v<std::expected<NotCopyAssignable, int>>);
63
64// !is_copy_constructible_v<T>
65static_assert(!std::is_copy_assignable_v<std::expected<NotCopyConstructible, int>>);
66
67// !is_copy_assignable_v<E>
68static_assert(!std::is_copy_assignable_v<std::expected<int, NotCopyAssignable>>);
69
70// !is_copy_constructible_v<E>
71static_assert(!std::is_copy_assignable_v<std::expected<int, NotCopyConstructible>>);
72
73// !is_nothrow_move_constructible_v<T> && is_nothrow_move_constructible_v<E>
74static_assert(std::is_copy_assignable_v<std::expected<MoveMayThrow, int>>);
75
76// is_nothrow_move_constructible_v<T> && !is_nothrow_move_constructible_v<E>
77static_assert(std::is_copy_assignable_v<std::expected<int, MoveMayThrow>>);
78
79// !is_nothrow_move_constructible_v<T> && !is_nothrow_move_constructible_v<E>
80static_assert(!std::is_copy_assignable_v<std::expected<MoveMayThrow, MoveMayThrow>>);
81
82constexpr bool test() {
83 // If this->has_value() && rhs.has_value() is true, equivalent to val = *rhs.
84 {
85 Traced::state oldState{};
86 Traced::state newState{};
87 std::expected<Traced, int> e1(std::in_place, oldState, 5);
88 const std::expected<Traced, int> e2(std::in_place, newState, 10);
89 decltype(auto) x = (e1 = e2);
90 static_assert(std::same_as<decltype(x), std::expected<Traced, int>&>);
91 assert(&x == &e1);
92
93 assert(e1.has_value());
94 assert(e1.value().data_ == 10);
95 assert(oldState.copyAssignCalled);
96 }
97
98 // - Otherwise, if this->has_value() is true, equivalent to:
99 // reinit-expected(unex, val, rhs.error())
100 // E move is not noexcept
101 // In this case, it should call the branch
102 //
103 // U tmp(std::move(oldval));
104 // destroy_at(addressof(oldval));
105 // try {
106 // construct_at(addressof(newval), std::forward<Args>(args)...);
107 // } catch (...) {
108 // construct_at(addressof(oldval), std::move(tmp));
109 // throw;
110 // }
111 //
112 {
113 TracedNoexcept::state oldState{};
114 Traced::state newState{};
115 std::expected<TracedNoexcept, Traced> e1(std::in_place, oldState, 5);
116 const std::expected<TracedNoexcept, Traced> e2(std::unexpect, newState, 10);
117
118 decltype(auto) x = (e1 = e2);
119 static_assert(std::same_as<decltype(x), std::expected<TracedNoexcept, Traced>&>);
120 assert(&x == &e1);
121
122 assert(!e1.has_value());
123 assert(e1.error().data_ == 10);
124
125 assert(!oldState.copyAssignCalled);
126 assert(oldState.moveCtorCalled);
127 assert(oldState.dtorCalled);
128 assert(!oldState.copyCtorCalled);
129 assert(newState.copyCtorCalled);
130 assert(!newState.moveCtorCalled);
131 assert(!newState.dtorCalled);
132 }
133
134 // - Otherwise, if this->has_value() is true, equivalent to:
135 // reinit-expected(unex, val, rhs.error())
136 // E move is noexcept
137 // In this case, it should call the branch
138 //
139 // destroy_at(addressof(oldval));
140 // construct_at(addressof(newval), std::forward<Args>(args)...);
141 //
142 {
143 Traced::state oldState{};
144 TracedNoexcept::state newState{};
145 std::expected<Traced, TracedNoexcept> e1(std::in_place, oldState, 5);
146 const std::expected<Traced, TracedNoexcept> e2(std::unexpect, newState, 10);
147
148 decltype(auto) x = (e1 = e2);
149 static_assert(std::same_as<decltype(x), std::expected<Traced, TracedNoexcept>&>);
150 assert(&x == &e1);
151
152 assert(!e1.has_value());
153 assert(e1.error().data_ == 10);
154
155 assert(!oldState.copyAssignCalled);
156 assert(!oldState.moveCtorCalled);
157 assert(oldState.dtorCalled);
158 assert(!oldState.copyCtorCalled);
159 assert(newState.copyCtorCalled);
160 assert(!newState.moveCtorCalled);
161 assert(!newState.dtorCalled);
162 }
163
164 // - Otherwise, if rhs.has_value() is true, equivalent to:
165 // reinit-expected(val, unex, *rhs)
166 // T move is not noexcept
167 // In this case, it should call the branch
168 //
169 // U tmp(std::move(oldval));
170 // destroy_at(addressof(oldval));
171 // try {
172 // construct_at(addressof(newval), std::forward<Args>(args)...);
173 // } catch (...) {
174 // construct_at(addressof(oldval), std::move(tmp));
175 // throw;
176 // }
177 //
178 {
179 TracedNoexcept::state oldState{};
180 Traced::state newState{};
181 std::expected<Traced, TracedNoexcept> e1(std::unexpect, oldState, 5);
182 const std::expected<Traced, TracedNoexcept> e2(std::in_place, newState, 10);
183
184 decltype(auto) x = (e1 = e2);
185 static_assert(std::same_as<decltype(x), std::expected<Traced, TracedNoexcept>&>);
186 assert(&x == &e1);
187
188 assert(e1.has_value());
189 assert(e1.value().data_ == 10);
190
191 assert(!oldState.copyAssignCalled);
192 assert(oldState.moveCtorCalled);
193 assert(oldState.dtorCalled);
194 assert(!oldState.copyCtorCalled);
195 assert(newState.copyCtorCalled);
196 assert(!newState.moveCtorCalled);
197 assert(!newState.dtorCalled);
198 }
199
200 // - Otherwise, if rhs.has_value() is true, equivalent to:
201 // reinit-expected(val, unex, *rhs)
202 // T move is noexcept
203 // In this case, it should call the branch
204 //
205 // destroy_at(addressof(oldval));
206 // construct_at(addressof(newval), std::forward<Args>(args)...);
207 //
208 {
209 Traced::state oldState{};
210 TracedNoexcept::state newState{};
211 std::expected<TracedNoexcept, Traced> e1(std::unexpect, oldState, 5);
212 const std::expected<TracedNoexcept, Traced> e2(std::in_place, newState, 10);
213
214 decltype(auto) x = (e1 = e2);
215 static_assert(std::same_as<decltype(x), std::expected<TracedNoexcept, Traced>&>);
216 assert(&x == &e1);
217
218 assert(e1.has_value());
219 assert(e1.value().data_ == 10);
220
221 assert(!oldState.copyAssignCalled);
222 assert(!oldState.moveCtorCalled);
223 assert(oldState.dtorCalled);
224 assert(!oldState.copyCtorCalled);
225 assert(newState.copyCtorCalled);
226 assert(!newState.moveCtorCalled);
227 assert(!newState.dtorCalled);
228 }
229
230 // Otherwise, equivalent to unex = rhs.error().
231 {
232 Traced::state oldState{};
233 Traced::state newState{};
234 std::expected<int, Traced> e1(std::unexpect, oldState, 5);
235 const std::expected<int, Traced> e2(std::unexpect, newState, 10);
236 decltype(auto) x = (e1 = e2);
237 static_assert(std::same_as<decltype(x), std::expected<int, Traced>&>);
238 assert(&x == &e1);
239
240 assert(!e1.has_value());
241 assert(e1.error().data_ == 10);
242 assert(oldState.copyAssignCalled);
243 }
244
245 // CheckForInvalidWrites
246 {
247 {
248 CheckForInvalidWrites<true> e1(std::unexpect);
249 CheckForInvalidWrites<true> e2;
250
251 e1 = e2;
252
253 assert(e1.check());
254 assert(e2.check());
255 }
256 {
257 CheckForInvalidWrites<false> e1(std::unexpect);
258 CheckForInvalidWrites<false> e2;
259
260 e1 = e2;
261
262 assert(e1.check());
263 assert(e2.check());
264 }
265 }
266
267 return true;
268}
269
270void testException() {
271#ifndef TEST_HAS_NO_EXCEPTIONS
272 struct ThrowOnCopyMoveMayThrow {
273 ThrowOnCopyMoveMayThrow() = default;
274 ThrowOnCopyMoveMayThrow(const ThrowOnCopyMoveMayThrow&) { throw Except{}; };
275 ThrowOnCopyMoveMayThrow& operator=(const ThrowOnCopyMoveMayThrow&) = default;
276 ThrowOnCopyMoveMayThrow(ThrowOnCopyMoveMayThrow&&) noexcept(false) {}
277 };
278
279 // assign value throw on copy
280 {
281 std::expected<ThrowOnCopyMoveMayThrow, int> e1(std::unexpect, 5);
282 const std::expected<ThrowOnCopyMoveMayThrow, int> e2(std::in_place);
283 try {
284 e1 = e2;
285 assert(false);
286 } catch (Except) {
287 assert(!e1.has_value());
288 assert(e1.error() == 5);
289 }
290 }
291
292 // assign error throw on copy
293 {
294 std::expected<int, ThrowOnCopyMoveMayThrow> e1(5);
295 const std::expected<int, ThrowOnCopyMoveMayThrow> e2(std::unexpect);
296 try {
297 e1 = e2;
298 assert(false);
299 } catch (Except) {
300 assert(e1.has_value());
301 assert(e1.value() == 5);
302 }
303 }
304#endif // TEST_HAS_NO_EXCEPTIONS
305}
306
307int main(int, char**) {
308 test();
309 static_assert(test());
310 testException();
311 return 0;
312}
313

source code of libcxx/test/std/utilities/expected/expected.expected/assign/assign.copy.pass.cpp