private static void addTypeToWorkList(ArrayList<ClassDef> worklist, Ref<? extends Type> ref) {
Type sup = Types.get(ref);
sup = Types.baseType(sup);
// can be a parameter type
if (sup instanceof ParameterType) return;
if (!(sup instanceof X10ParsedClassType)) assert sup instanceof X10ParsedClassType;
worklist.add(((X10ParsedClassType) sup).def());
}
