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

// { dg-do run { target c++17 }  }

// Copyright (C) 2013-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

#include <optional>
#include <testsuite_hooks.h>

struct value_type
{
  int i;
};

int main()
{
  {
    std::optional<value_type> o { value_type { 51 } };
    VERIFY( o.value().i == 51 );
    VERIFY( o.value().i == (*o).i );
    VERIFY( &o.value().i == &(*o).i );
  }

  {
    enum outcome_type { nothrow, caught, bad_catch };

    outcome_type outcome {};
    std::optional<value_type> o = std::nullopt;
    bool called = false;
    auto const eat = [&called](int) { called = true; };

    try
    {
      eat(o.value().i);
    }
    catch(std::bad_optional_access const&)
    { outcome = caught; }
    catch(...)
    { outcome = bad_catch; }

    VERIFY( outcome == caught );
    VERIFY( !called );
  }
}