libcxx/test/std/utilities/utility/pairs/pairs.pair/assign_const_move_pair.pass.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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
  10
  11 // <utility>
  12
  13 // template <class T1, class T2> struct pair
  14 // constexpr const pair& operator=(pair&& p) const;
  15
  16 #include <cassert>
  17 #include <utility>
  18
  19 #include "test_macros.h"
  20 #include "copy_move_types.h"
  21
  22 // Constraints:
  23 // is_assignable<const first_type&, first_type> is true and
  24 // is_assignable<const second_type&, second_type> is true.
  25
  26 // clang-format off
  27 static_assert(std::is_assignable_v<const std::pair<int&&, int&&>&,
  28                                    std::pair<int&&, int&&>&&>);
  29 static_assert(!std::is_assignable_v<const std::pair<int, int>&,
  30                                     std::pair<int, int>&&>);
  31 static_assert(!std::is_assignable_v<const std::pair<int, int&&>&,
  32                                     std::pair<int, int&&>&&>);
  33 static_assert(!std::is_assignable_v<const std::pair<int&&, int>&,
  34                                     std::pair<int&&, int>&&>);
  35
  36 static_assert(std::is_assignable_v<const std::pair<ConstMoveAssign, ConstMoveAssign>&,
  37                                    std::pair<ConstMoveAssign, ConstMoveAssign>&&>);
  38 static_assert(!std::is_assignable_v<const std::pair<MoveAssign, MoveAssign>&,
  39                                    std::pair<MoveAssign, MoveAssign>&&>);
  40
  41 // clang-format on
  42
  43 constexpr bool test() {
  44   // reference types
  45   {
  46     int i1    = 1;
  47     int i2    = 2;
  48     double d1 = 3.0;
  49     double d2 = 5.0;
  50     std::pair<int&&, double&&> p1{std::move(i1), std::move(d1)};
  51     const std::pair<int&&, double&&> p2{std::move(i2), std::move(d2)};
  52     p2 = std::move(p1);
  53     assert(p2.first == 1);
  54     assert(p2.second == 3.0);
  55   }
  56
  57   // user defined const move assignment
  58   {
  59     std::pair<ConstMoveAssign, ConstMoveAssign> p1{1, 2};
  60     const std::pair<ConstMoveAssign, ConstMoveAssign> p2{3, 4};
  61     p2 = std::move(p1);
  62     assert(p2.first.val == 1);
  63     assert(p2.second.val == 2);
  64   }
  65
  66   // The correct assignment operator of the underlying type is used
  67   {
  68     std::pair<TracedAssignment, const TracedAssignment> t1{};
  69     const std::pair<TracedAssignment, const TracedAssignment> t2{};
  70     t2 = std::move(t1);
  71     assert(t2.first.constMoveAssign == 1);
  72     assert(t2.second.constCopyAssign == 1);
  73   }
  74
  75   return true;
  76 }
  77
  78 int main(int, char**) {
  79   test();
  80 // gcc cannot have mutable member in constant expression
  81 #if !defined(TEST_COMPILER_GCC)
  82   static_assert(test());
  83 #endif
  84   return 0;
  85 }