void attribBounds(List<JCTypeParameter> typarams) {
        for (JCTypeParameter typaram : typarams) {
            Type bound = typaram.type.getUpperBound();
            if (bound != null && bound.tsym instanceof ClassSymbol) {
                ClassSymbol c = (ClassSymbol)bound.tsym;
                if ((c.flags_field & COMPOUND) != 0) {
                    assert (c.flags_field & UNATTRIBUTED) != 0 : c;
                    attribClass(typaram.pos(), c);
                }
            }
        }
    }