libstdc++-v3/testsuite/20_util/optional/in_place.cc

   1 // { dg-do run { target c++17 }  }
   2
   3 // Copyright (C) 2013-2022 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 #include <vector>
  24
  25 int main()
  26 {
  27   // [20.5.5] In-place construction
  28   {
  29     std::optional<int> o { std::in_place };
  30     VERIFY( o );
  31     VERIFY( *o == int() );
  32
  33     static_assert( !std::is_convertible<std::in_place_t, std::optional<int>>(), "" );
  34   }
  35
  36   {
  37     std::optional<int> o { std::in_place, 42 };
  38     VERIFY( o );
  39     VERIFY( *o == 42 );
  40   }
  41
  42   {
  43     std::optional<std::vector<int>> o { std::in_place, 18, 4 };
  44     VERIFY( o );
  45     VERIFY( o->size() == 18 );
  46     VERIFY( (*o)[17] == 4 );
  47   }
  48
  49   {
  50     std::optional<std::vector<int>> o { std::in_place, { 18, 4 } };
  51     VERIFY( o );
  52     VERIFY( o->size() == 2 );
  53     VERIFY( (*o)[0] == 18 );
  54   }
  55
  56   {
  57     std::optional<std::vector<int>> o { std::in_place, { 18, 4 }, std::allocator<int> {} };
  58     VERIFY( o );
  59     VERIFY( o->size() == 2 );
  60     VERIFY( (*o)[0] == 18 );
  61   }
  62 }