libcxx/test/std/utilities/utility/pairs/pairs.pair/assign_pair_cxx03.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 // REQUIRES: c++03
  10
  11 // <utility>
  12
  13 // template <class T1, class T2> struct pair
  14
  15 // pair& operator=(pair const& p);
  16
  17 #include <utility>
  18 #include <memory>
  19 #include <cassert>
  20
  21 #include "test_macros.h"
  22
  23 struct NonAssignable {
  24   NonAssignable() {}
  25 private:
  26   NonAssignable& operator=(NonAssignable const&);
  27 };
  28
  29 struct Incomplete;
  30 extern Incomplete inc_obj;
  31
  32 struct ConstructibleFromInt {
  33   ConstructibleFromInt() : value(-1) { }
  34   explicit ConstructibleFromInt(int v) : value(v) { }
  35   int value;
  36 };
  37
  38 int main(int, char**)
  39 {
  40     {
  41       // Test that we don't constrain the assignment operator in C++03 mode.
  42       // Since we don't have access control SFINAE having pair evaluate SFINAE
  43       // may cause a hard error.
  44       typedef std::pair<int, NonAssignable> P;
  45       static_assert(std::is_copy_assignable<P>::value, "");
  46     }
  47     {
  48       typedef std::pair<int, Incomplete&> P;
  49       static_assert(std::is_copy_assignable<P>::value, "");
  50       P p(42, inc_obj);
  51       assert(&p.second == &inc_obj);
  52     }
  53     {
  54       // The type is constructible from int, but not assignable from int.
  55       // This ensures that operator=(pair const&) can be used in conjunction with
  56       // pair(pair<U, V> const&) to mimic operator=(pair<U, V> const&) in C++03.
  57       // This is weird but valid in C++03.
  58       std::pair<ConstructibleFromInt, char> p;
  59       std::pair<int, char> from(11, 'x');
  60       p = from;
  61       assert(p.first.value == 11);
  62       assert(p.second == 'x');
  63     }
  64
  65   return 0;
  66 }
  67
  68 struct Incomplete {};
  69 Incomplete inc_obj;