144 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++0310 11// <utility>12 13// template <class T1, class T2> struct pair14 15// pair& operator=(pair&& p);16 17#include <utility>18#include <memory>19#include <cassert>20 21#include "test_macros.h"22#include "archetypes.h"23 24struct CountAssign {25 int copied = 0;26 int moved = 0;27 TEST_CONSTEXPR_CXX20 CountAssign() = default;28 TEST_CONSTEXPR_CXX20 CountAssign& operator=(CountAssign const&) {29 ++copied;30 return *this;31 }32 TEST_CONSTEXPR_CXX20 CountAssign& operator=(CountAssign&&) {33 ++moved;34 return *this;35 }36};37 38struct NotAssignable {39 NotAssignable& operator=(NotAssignable const&) = delete;40 NotAssignable& operator=(NotAssignable&&) = delete;41};42 43struct MoveAssignable {44 MoveAssignable& operator=(MoveAssignable const&) = delete;45 MoveAssignable& operator=(MoveAssignable&&) = default;46};47 48struct CopyAssignable {49 CopyAssignable& operator=(CopyAssignable const&) = default;50 CopyAssignable& operator=(CopyAssignable&&) = delete;51};52 53TEST_CONSTEXPR_CXX20 bool test() {54 {55 typedef std::pair<ConstexprTestTypes::MoveOnly, int> P;56 P p1(3, 4);57 P p2;58 p2 = std::move(p1);59 assert(p2.first.value == 3);60 assert(p2.second == 4);61 }62 {63 using P = std::pair<int&, int&&>;64 int x = 42;65 int y = 101;66 int x2 = -1;67 int y2 = 300;68 P p1(x, std::move(y));69 P p2(x2, std::move(y2));70 p1 = std::move(p2);71 assert(p1.first == x2);72 assert(p1.second == y2);73 }74 {75 using P = std::pair<int, ConstexprTestTypes::DefaultOnly>;76 static_assert(!std::is_move_assignable<P>::value, "");77 }78 {79 // The move decays to the copy constructor80 using P = std::pair<CountAssign, ConstexprTestTypes::CopyOnly>;81 static_assert(std::is_move_assignable<P>::value, "");82 P p;83 P p2;84 p = std::move(p2);85 assert(p.first.moved == 0);86 assert(p.first.copied == 1);87 assert(p2.first.moved == 0);88 assert(p2.first.copied == 0);89 }90 {91 using P = std::pair<CountAssign, ConstexprTestTypes::MoveOnly>;92 static_assert(std::is_move_assignable<P>::value, "");93 P p;94 P p2;95 p = std::move(p2);96 assert(p.first.moved == 1);97 assert(p.first.copied == 0);98 assert(p2.first.moved == 0);99 assert(p2.first.copied == 0);100 }101 {102 using P1 = std::pair<int, NotAssignable>;103 using P2 = std::pair<NotAssignable, int>;104 using P3 = std::pair<NotAssignable, NotAssignable>;105 static_assert(!std::is_move_assignable<P1>::value, "");106 static_assert(!std::is_move_assignable<P2>::value, "");107 static_assert(!std::is_move_assignable<P3>::value, "");108 }109 {110 // We assign through the reference and don't move out of the incoming ref,111 // so this doesn't work (but would if the type were CopyAssignable).112 using P1 = std::pair<MoveAssignable&, int>;113 static_assert(!std::is_move_assignable<P1>::value, "");114 115 // ... works if it's CopyAssignable116 using P2 = std::pair<CopyAssignable&, int>;117 static_assert(std::is_move_assignable<P2>::value, "");118 119 // For rvalue-references, we can move-assign if the type is MoveAssignable120 // or CopyAssignable (since in the worst case the move will decay into a copy).121 using P3 = std::pair<MoveAssignable&&, int>;122 using P4 = std::pair<CopyAssignable&&, int>;123 static_assert(std::is_move_assignable<P3>::value, "");124 static_assert(std::is_move_assignable<P4>::value, "");125 126 // In all cases, we can't move-assign if the types are not assignable,127 // since we assign through the reference.128 using P5 = std::pair<NotAssignable&, int>;129 using P6 = std::pair<NotAssignable&&, int>;130 static_assert(!std::is_move_assignable<P5>::value, "");131 static_assert(!std::is_move_assignable<P6>::value, "");132 }133 return true;134}135 136int main(int, char**) {137 test();138#if TEST_STD_VER >= 20139 static_assert(test());140#endif141 142 return 0;143}144