ERROR: permission info at index 1 ....

   After a61b1f74823c commit, below query reports error:

 create table perm_test1(a int);

 create table perm_test2(b int);

 select subq.c0

from (select (select a from perm_test1 order by a limit 1) as c0, b as c1 from perm_test2 where false order by c0, c1) as subq where false;

Below codes can fix this:

--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -512,11 +512,16 @@ flatten_rtes_walker(Node *node, flatten_rtes_walker_context *cxt)
                 * Recurse into subselects.  Must update cxt->query to this query so
                 * that the rtable and rteperminfos correspond with each other.
                 */
+               Query *current_query = cxt->query;
+               bool result;
+
                cxt->query = (Query *) node;
-               return query_tree_walker((Query *) node,
+               result = query_tree_walker((Query *) node,
                                                                 flatten_rtes_walker,
                                                                 (void *) cxt,
                                                                 QTW_EXAMINE_RTES_BEFORE);
+               cxt->query = current_query;
+               return result;
        }

                                                                                     regards, tender wang