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 G>
12// constexpr expected& operator=(unexpected<G>&& e);
13//
14// Let GF be G
15// Constraints:
16// - is_constructible_v<E, GF> is true; and
17// - is_assignable_v<E&, GF> is true; and
18// - is_nothrow_constructible_v<E, GF> || is_nothrow_move_constructible_v<T> ||
19// is_nothrow_move_constructible_v<E> is true.
20//
21// Effects:
22// - If has_value() is true, equivalent to:
23// reinit-expected(unex, val, std::forward<GF>(e.error()));
24// has_val = false;
25// - Otherwise, equivalent to: unex = std::forward<GF>(e.error());
26// Returns: *this.
27
28#include <cassert>
29#include <concepts>
30#include <expected>
31#include <type_traits>
32#include <utility>
33
34#include "../../types.h"
35#include "test_macros.h"
36
37struct NotMoveConstructible {
38 NotMoveConstructible(NotMoveConstructible&&) = delete;
39 NotMoveConstructible& operator=(NotMoveConstructible&&) = default;
40};
41
42struct NotMoveAssignable {
43 NotMoveAssignable(NotMoveAssignable&&) = default;
44 NotMoveAssignable& operator=(NotMoveAssignable&&) = delete;
45};
46
47struct MoveMayThrow {
48 MoveMayThrow(MoveMayThrow const&) = default;
49 MoveMayThrow& operator=(const MoveMayThrow&) = default;
50 MoveMayThrow(MoveMayThrow&&) noexcept(false) {}
51 MoveMayThrow& operator=(MoveMayThrow&&) noexcept(false) { return *this; }
52};
53
54// Test constraints
55static_assert(std::is_assignable_v<std::expected<int, int>&, std::unexpected<int>&&>);
56
57// !is_constructible_v<E, GF>
58static_assert(
59 !std::is_assignable_v<std::expected<int, NotMoveConstructible>&, std::unexpected<NotMoveConstructible>&&>);
60
61// !is_assignable_v<E&, GF>
62static_assert(!std::is_assignable_v<std::expected<int, NotMoveAssignable>&, std::unexpected<NotMoveAssignable>&&>);
63
64template <bool moveNoexcept, bool convertNoexcept>
65struct MaybeNoexcept {
66 explicit MaybeNoexcept(int) noexcept(convertNoexcept);
67 MaybeNoexcept(MaybeNoexcept&&) noexcept(moveNoexcept);
68 MaybeNoexcept& operator=(MaybeNoexcept&&) = default;
69 MaybeNoexcept& operator=(int);
70};
71
72// !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> &&
73// is_nothrow_move_constructible_v<E>
74static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<true, false>>&,
75 std::unexpected<int>&&>);
76
77// is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> &&
78// !is_nothrow_move_constructible_v<E>
79static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<false, true>>&,
80 std::unexpected<int>&&>);
81
82// !is_nothrow_constructible_v<E, GF> && is_nothrow_move_constructible_v<T> &&
83// !is_nothrow_move_constructible_v<E>
84static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<true, true>, MaybeNoexcept<false, false>>&,
85 std::unexpected<int>&&>);
86
87// !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> &&
88// !is_nothrow_move_constructible_v<E>
89static_assert(!std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<false, false>>&,
90 std::unexpected<int>&&>);
91
92constexpr bool test() {
93 // - If has_value() is true, equivalent to:
94 // reinit-expected(unex, val, std::forward<GF>(e.error()));
95 // is_nothrow_constructible_v<E, GF>
96 //
97 // In this case, it should call the branch
98 // destroy_at(addressof(oldval));
99 // construct_at(addressof(newval), std::forward<Args>(args)...);
100 {
101 BothNoexcept::state oldState{};
102 std::expected<BothNoexcept, BothNoexcept> e(std::in_place, oldState, 5);
103 std::unexpected<int> un(10);
104 decltype(auto) x = (e = std::move(un));
105 static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, BothNoexcept>&>);
106 assert(&x == &e);
107
108 assert(!oldState.moveCtorCalled);
109 assert(oldState.dtorCalled);
110 assert(e.error().movedFromInt);
111 }
112
113 // - If has_value() is true, equivalent to:
114 // reinit-expected(unex, val, std::forward<GF>(e.error()));
115 // !is_nothrow_constructible_v<E, GF> && is_nothrow_move_constructible_v<E>
116 //
117 // In this case, it should call the branch
118 // T tmp(std::forward<Args>(args)...);
119 // destroy_at(addressof(oldval));
120 // construct_at(addressof(newval), std::move(tmp));
121 {
122 BothNoexcept::state oldState{};
123 std::expected<BothNoexcept, MoveNoexceptConvThrow> e(std::in_place, oldState, 5);
124 std::unexpected<int> un(10);
125 decltype(auto) x = (e = std::move(un));
126 static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, MoveNoexceptConvThrow>&>);
127 assert(&x == &e);
128
129 assert(!oldState.moveCtorCalled);
130 assert(oldState.dtorCalled);
131 assert(!e.error().movedFromInt);
132 assert(e.error().movedFromTmp);
133 }
134
135 // - If has_value() is true, equivalent to:
136 // reinit-expected(unex, val, std::forward<GF>(e.error()));
137 // !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<E>
138 // is_nothrow_move_constructible_v<T>
139 //
140 // In this case, it should call the branch
141 // U tmp(std::move(oldval));
142 // destroy_at(addressof(oldval));
143 // try {
144 // construct_at(addressof(newval), std::forward<Args>(args)...);
145 // } catch (...) {
146 // construct_at(addressof(oldval), std::move(tmp));
147 // throw;
148 // }
149 {
150 BothNoexcept::state oldState{};
151 std::expected<BothNoexcept, BothMayThrow> e(std::in_place, oldState, 5);
152 std::unexpected<int> un(10);
153 decltype(auto) x = (e = std::move(un));
154 static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, BothMayThrow>&>);
155 assert(&x == &e);
156
157 assert(oldState.moveCtorCalled);
158 assert(oldState.dtorCalled);
159 assert(e.error().movedFromInt);
160 }
161
162 // Otherwise, equivalent to: unex = std::forward<GF>(e.error());
163 {
164 Traced::state oldState{};
165 Traced::state newState{};
166 std::expected<int, Traced> e1(std::unexpect, oldState, 5);
167 std::unexpected<Traced> e(std::in_place, newState, 10);
168 decltype(auto) x = (e1 = std::move(e));
169 static_assert(std::same_as<decltype(x), std::expected<int, Traced >&>);
170 assert(&x == &e1);
171
172 assert(!e1.has_value());
173 assert(e1.error().data_ == 10);
174 assert(oldState.moveAssignCalled);
175 }
176 return true;
177}
178
179void testException() {
180#ifndef TEST_HAS_NO_EXCEPTIONS
181 std::expected<int, ThrowOnConvert> e1(std::in_place, 5);
182 std::unexpected<int> un(10);
183 try {
184 e1 = std::move(un);
185 assert(false);
186 } catch (Except) {
187 assert(e1.has_value());
188 assert(*e1 == 5);
189 }
190#endif // TEST_HAS_NO_EXCEPTIONS
191}
192
193int main(int, char**) {
194 test();
195 static_assert(test());
196 testException();
197 return 0;
198}
199

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