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

   1 // { dg-options "-std=gnu++17" }
   2 // { dg-do compile { target c++17 }  }
   3
   4 // Copyright (C) 2013-2021 Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING3.  If not see
  19 // <http://www.gnu.org/licenses/>.
  20
  21 #include <optional>
  22 #include <testsuite_hooks.h>
  23
  24 int main()
  25 {
  26   // [20.5.5] In-place construction
  27   {
  28     constexpr std::optional<int> o { std::in_place };
  29     static_assert( o, "" );
  30     static_assert( *o == int {}, "" );
  31
  32     static_assert( !std::is_convertible<std::in_place_t, std::optional<int>>(), "" );
  33   }
  34
  35   {
  36     constexpr std::optional<int> o { std::in_place, 42 };
  37     static_assert( o, "" );
  38     static_assert( *o == 42, "" );
  39   }
  40 }