interface ihello
{
  in void hello();
  out void world();
  behaviour
  {
    on hello: {}
    on inevitable: world;
  }
}

interface iworld
{
  in void hello();
  out void cruel();
  out void world();

  behaviour
  {
    bool enabled = false;
    on inevitable: {enabled = true; cruel; world;}
    [enabled] on hello: enabled = false;
    [!enabled] on hello: illegal;
  }
}

component hello_inevitable_sync_out
{
  provides ihello h;
  requires iworld w;

  behaviour
  {
    on h.hello(): {}
    on w.cruel(): w.hello();
    on w.world(): h.world();
  }
}