*  @param t1           The first argument type.
     *  @param t2           The second argument type.
     */
    public boolean checkCompatibleAbstracts(DiagnosticPosition pos,
                                            Type t1,
                                            Type t2) {
        return checkCompatibleAbstracts(pos, t1, t2,
                                        types.makeCompoundType(t1, t2));
    }