libstdc++-v3/testsuite/30_threads/call_once/call_once1.cc

// { dg-do run { target c++11 } }
// { dg-additional-options "-pthread" { target pthread } }

// Copyright (C) 2008-2023 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 <mutex>
#include <system_error>
#include <testsuite_hooks.h>

std::once_flag value_flag;
int value = 1;

void add_to_value(int i)
{
  value += i;
}

int main()
{
  try
    {
      std::call_once(value_flag, add_to_value, 2);
      std::call_once(value_flag, add_to_value, 2);
    }
  catch (const std::system_error& e)
    {
      VERIFY( false );
    }
  catch (...)
    {
      VERIFY( false );
    }

  VERIFY( value == 3 );

  return 0;
}