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 // Older Clangs do not support the C++20 feature to constrain destructors 11 // XFAIL: clang-14, apple-clang-14 12 13 // template<class G> 14 // constexpr expected& operator=(unexpected<G>&& e); 15 // 16 // Let GF be G 17 // Constraints: 18 // - is_constructible_v<E, GF> is true; and 19 // - is_assignable_v<E&, GF> is true; and 20 // - is_nothrow_constructible_v<E, GF> || is_nothrow_move_constructible_v<T> || 21 // is_nothrow_move_constructible_v<E> is true. 22 // 23 // Effects: 24 // - If has_value() is true, equivalent to: 25 // reinit-expected(unex, val, std::forward<GF>(e.error())); 26 // has_val = false; 27 // - Otherwise, equivalent to: unex = std::forward<GF>(e.error()); 28 // Returns: *this. 29 30 #include <cassert> 31 #include <concepts> 32 #include <expected> 33 #include <type_traits> 34 #include <utility> 35 36 #include "../../types.h" 37 #include "test_macros.h" 38 39 struct NotMoveConstructible { 40 NotMoveConstructible(NotMoveConstructible&&) = delete; 41 NotMoveConstructible& operator=(NotMoveConstructible&&) = default; 42 }; 43 44 struct NotMoveAssignable { 45 NotMoveAssignable(NotMoveAssignable&&) = default; 46 NotMoveAssignable& operator=(NotMoveAssignable&&) = delete; 47 }; 48 49 struct MoveMayThrow { 50 MoveMayThrow(MoveMayThrow const&) = default; 51 MoveMayThrow& operator=(const MoveMayThrow&) = default; 52 MoveMayThrow(MoveMayThrow&&) noexcept(false) {} 53 MoveMayThrow& operator=(MoveMayThrow&&) noexcept(false) { return *this; } 54 }; 55 56 // Test constraints 57 static_assert(std::is_assignable_v<std::expected<int, int>&, std::unexpected<int>&&>); 58 59 // !is_constructible_v<E, GF> 60 static_assert( 61 !std::is_assignable_v<std::expected<int, NotMoveConstructible>&, std::unexpected<NotMoveConstructible>&&>); 62 63 // !is_assignable_v<E&, GF> 64 static_assert(!std::is_assignable_v<std::expected<int, NotMoveAssignable>&, std::unexpected<NotMoveAssignable>&&>); 65 66 template <bool moveNoexcept, bool convertNoexcept> 67 struct MaybeNoexcept { 68 explicit MaybeNoexcept(int) noexcept(convertNoexcept); 69 MaybeNoexcept(MaybeNoexcept&&) noexcept(moveNoexcept); 70 MaybeNoexcept& operator=(MaybeNoexcept&&) = default; 71 MaybeNoexcept& operator=(int); 72 }; 73 74 // !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> && 75 // is_nothrow_move_constructible_v<E> 76 static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<true, false>>&, 77 std::unexpected<int>&&>); 78 79 // is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> && 80 // !is_nothrow_move_constructible_v<E> 81 static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<false, true>>&, 82 std::unexpected<int>&&>); 83 84 // !is_nothrow_constructible_v<E, GF> && is_nothrow_move_constructible_v<T> && 85 // !is_nothrow_move_constructible_v<E> 86 static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<true, true>, MaybeNoexcept<false, false>>&, 87 std::unexpected<int>&&>); 88 89 // !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> && 90 // !is_nothrow_move_constructible_v<E> 91 static_assert(!std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<false, false>>&, 92 std::unexpected<int>&&>); 93 94 constexpr bool test() { 95 // - If has_value() is true, equivalent to: 96 // reinit-expected(unex, val, std::forward<GF>(e.error())); 97 // is_nothrow_constructible_v<E, GF> 98 // 99 // In this case, it should call the branch 100 // destroy_at(addressof(oldval)); 101 // construct_at(addressof(newval), std::forward<Args>(args)...); 102 { 103 BothNoexcept::state oldState{}; 104 std::expected<BothNoexcept, BothNoexcept> e(std::in_place, oldState, 5); 105 std::unexpected<int> un(10); 106 decltype(auto) x = (e = std::move(un)); 107 static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, BothNoexcept>&>); 108 assert(&x == &e); 109 110 assert(!oldState.moveCtorCalled); 111 assert(oldState.dtorCalled); 112 assert(e.error().movedFromInt); 113 } 114 115 // - If has_value() is true, equivalent to: 116 // reinit-expected(unex, val, std::forward<GF>(e.error())); 117 // !is_nothrow_constructible_v<E, GF> && is_nothrow_move_constructible_v<E> 118 // 119 // In this case, it should call the branch 120 // T tmp(std::forward<Args>(args)...); 121 // destroy_at(addressof(oldval)); 122 // construct_at(addressof(newval), std::move(tmp)); 123 { 124 BothNoexcept::state oldState{}; 125 std::expected<BothNoexcept, MoveNoexceptConvThrow> e(std::in_place, oldState, 5); 126 std::unexpected<int> un(10); 127 decltype(auto) x = (e = std::move(un)); 128 static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, MoveNoexceptConvThrow>&>); 129 assert(&x == &e); 130 131 assert(!oldState.moveCtorCalled); 132 assert(oldState.dtorCalled); 133 assert(!e.error().movedFromInt); 134 assert(e.error().movedFromTmp); 135 } 136 137 // - If has_value() is true, equivalent to: 138 // reinit-expected(unex, val, std::forward<GF>(e.error())); 139 // !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<E> 140 // is_nothrow_move_constructible_v<T> 141 // 142 // In this case, it should call the branch 143 // U tmp(std::move(oldval)); 144 // destroy_at(addressof(oldval)); 145 // try { 146 // construct_at(addressof(newval), std::forward<Args>(args)...); 147 // } catch (...) { 148 // construct_at(addressof(oldval), std::move(tmp)); 149 // throw; 150 // } 151 { 152 BothNoexcept::state oldState{}; 153 std::expected<BothNoexcept, BothMayThrow> e(std::in_place, oldState, 5); 154 std::unexpected<int> un(10); 155 decltype(auto) x = (e = std::move(un)); 156 static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, BothMayThrow>&>); 157 assert(&x == &e); 158 159 assert(oldState.moveCtorCalled); 160 assert(oldState.dtorCalled); 161 assert(e.error().movedFromInt); 162 } 163 164 // Otherwise, equivalent to: unex = std::forward<GF>(e.error()); 165 { 166 Traced::state oldState{}; 167 Traced::state newState{}; 168 std::expected<int, Traced> e1(std::unexpect, oldState, 5); 169 std::unexpected<Traced> e(std::in_place, newState, 10); 170 decltype(auto) x = (e1 = std::move(e)); 171 static_assert(std::same_as<decltype(x), std::expected<int, Traced >&>); 172 assert(&x == &e1); 173 174 assert(!e1.has_value()); 175 assert(e1.error().data_ == 10); 176 assert(oldState.moveAssignCalled); 177 } 178 return true; 179 } 180 181 void testException() { 182 #ifndef TEST_HAS_NO_EXCEPTIONS 183 std::expected<void, ThrowOnMoveConstruct> e1(std::in_place); 184 std::unexpected<ThrowOnMoveConstruct> un(std::in_place); 185 try { 186 e1 = std::move(un); 187 assert(false); 188 } catch (Except) { 189 assert(e1.has_value()); 190 } 191 #endif // TEST_HAS_NO_EXCEPTIONS 192 } 193 194 int main(int, char**) { 195 test(); 196 static_assert(test()); 197 testException(); 198 return 0; 199 } 200