eval.c:1676
static VALUE
ev_const_get(cref, id, self)
    NODE *cref;
    ID id;
    VALUE self;
{
    NODE *cbase = cref;
    VALUE result;

    while (cbase && cbase->nd_next) {
	VALUE klass = cbase->nd_clss;

	if (NIL_P(klass)) return rb_const_get(CLASS_OF(self), id);
	while (RCLASS(klass)->iv_tbl && st_lookup(RCLASS(klass)->iv_tbl, id, &result)) {
	    if (result == Qundef) {
		rb_autoload_load(klass, id);
		continue;
	    }
	    return result;
	}
	cbase = cbase->nd_next;
    }
    return rb_const_get(cref->nd_clss, id);
}
