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

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

// Copyright (C) 2013-2025 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;
};

#if __cpp_lib_constexpr_exceptions >= 202502L
void eat(int x)
{
}

constexpr bool test01()
{
  enum outcome_type { nothrow, caught, bad_catch };

  outcome_type outcome {};
  std::optional<value_type> o = std::nullopt;

  try
  {
    eat(o.value().i);
  }
  catch(std::bad_optional_access const& x)
  {
    outcome = caught;
    long c = x.what()[0];
    VERIFY( c == x.what()[0] );
  }
  catch(...)
  { outcome = bad_catch; }

  VERIFY( outcome == caught );
  return true;
}

static_assert( test01() );
#endif

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