libstdc++-v3/testsuite/20_util/optional/constexpr/observers/3.cc

   1 // { dg-options "-std=gnu++17" }
   2
   3 // Copyright (C) 2013-2018 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
  22 struct value_type
  23 {
  24   int i;
  25 };
  26
  27 int main()
  28 {
  29   constexpr std::optional<value_type> o { value_type { 51 } };
  30   static_assert( o.value().i == 51, "" );
  31   static_assert( o.value().i == (*o).i, "" );
  32   static_assert( &o.value().i == &(*o).i, "" );
  33 }