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

component guardifnest {
  provides iguardifnest p;
  behaviour {
    bool b = false;
    on p.e():
      {
        [b] {
          if (false)
            illegal;
          else if (false)
            p.a();
        }
        [!b]
          p.c();
        [otherwise]
          illegal;
      }
  }
}