libstdc++-v3/testsuite/20_util/optional/assignment/6.cc

   1 // { dg-do run { target c++17 }  }
   2
   3 // Copyright (C) 2013-2024 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20 #include <optional>
  21 #include <testsuite_hooks.h>
  22
  23 int counter = 0;
  24
  25 struct mixin_counter
  26 {
  27   mixin_counter() { ++counter; }
  28   mixin_counter(mixin_counter const&) { ++counter; }
  29   ~mixin_counter() { --counter; }
  30 };
  31
  32 struct value_type : private mixin_counter
  33 {
  34   value_type() = default;
  35   value_type(int) : state(1) { }
  36   value_type(std::initializer_list<char>, const char*) : state(2) { }
  37   int state = 0;
  38 };
  39
  40 int main()
  41 {
  42   using O = std::optional<value_type>;
  43
  44   // Check emplace
  45
  46   {
  47     O o;
  48     o.emplace();
  49     VERIFY( o && o->state == 0 );
  50   }
  51   {
  52     O o { std::in_place, 0 };
  53     o.emplace();
  54     VERIFY( o && o->state == 0 );
  55   }
  56
  57   {
  58     O o;
  59     o.emplace(0);
  60     VERIFY( o && o->state == 1 );
  61   }
  62   {
  63     O o { std::in_place };
  64     o.emplace(0);
  65     VERIFY( o && o->state == 1 );
  66   }
  67
  68   {
  69     O o;
  70     o.emplace({ 'a' }, "");
  71     VERIFY( o && o->state == 2 );
  72   }
  73   {
  74     O o { std::in_place };
  75     o.emplace({ 'a' }, "");
  76     VERIFY( o && o->state == 2 );
  77   }
  78   {
  79     O o;
  80     VERIFY(&o.emplace(0) == &*o);
  81     VERIFY(&o.emplace({ 'a' }, "") == &*o);
  82   }
  83
  84   static_assert( !std::is_constructible<O, std::initializer_list<int>, int>(), "" );
  85
  86   VERIFY( counter == 0 );
  87 }