interface iifnest {
  in void e();
  out void a();
  out void b();
  out void c();
  behaviour {
    on e: c;
  }
}

component ifnest {
  provides iifnest p;
  behaviour {

    on p.e(): nest();

    void nest()
    {
      bool b = false;

      if (b)
      {
        if (false)
          illegal;
        else if (false)
          p.a();
      }
      else if (true)
        p.c();
      else
        illegal;
    }
  }
}