Math overflow problem in Cool equality

overflow-eq.cl

class Main inherits IO {
    main() : SELF_TYPE {
        {
            out_eq(2147483647+2147483647, ~2);
            out_eq(2*2147483647, ~2);
        }
    };

    out_eq(a : Int, b : Int) : SELF_TYPE {
        out_int(a).out_string(" = ").out_int(b).out_string(" <==> ")
            .out_string(if a = b then "true\n" else "false\n" fi)
    };
};