List<Type> attribExprs(List<JCExpression> trees, Env<AttrContext> env, Type pt) {
        ListBuffer<Type> ts = new ListBuffer<Type>();
        for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)
            ts.append(attribExpr(l.head, env, pt));
        return ts.toList();
    }