3 files changed, 109 insertions, 6 deletions

diff --git a/src/backend/parser/parse_cte.c b/src/backend/parser/parse_cte.c
index 1fca7485ca3..b24989e4170 100644
--- a/src/backend/parser/parse_cte.c
+++ b/src/backend/parser/parse_cte.c
@@ -537,15 +537,15 @@ makeDependencyGraphWalker(Node *node, CteState *cstate)
 				 * In the non-RECURSIVE case, query names are visible to the
 				 * WITH items after them and to the main query.
 				 */
-				ListCell   *cell1;
-
 				cstate->innerwiths = lcons(NIL, cstate->innerwiths);
-				cell1 = list_head(cstate->innerwiths);
 				foreach(lc, stmt->withClause->ctes)
 				{
 					CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
+					ListCell   *cell1;
 
 					(void) makeDependencyGraphWalker(cte->ctequery, cstate);
+					/* note that recursion could mutate innerwiths list */
+					cell1 = list_head(cstate->innerwiths);
 					lfirst(cell1) = lappend((List *) lfirst(cell1), cte);
 				}
 				(void) raw_expression_tree_walker(node,
@@ -813,15 +813,15 @@ checkWellFormedRecursionWalker(Node *node, CteState *cstate)
 				 * In the non-RECURSIVE case, query names are visible to the
 				 * WITH items after them and to the main query.
 				 */
-				ListCell   *cell1;
-
 				cstate->innerwiths = lcons(NIL, cstate->innerwiths);
-				cell1 = list_head(cstate->innerwiths);
 				foreach(lc, stmt->withClause->ctes)
 				{
 					CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
+					ListCell   *cell1;
 
 					(void) checkWellFormedRecursionWalker(cte->ctequery, cstate);
+					/* note that recursion could mutate innerwiths list */
+					cell1 = list_head(cstate->innerwiths);
 					lfirst(cell1) = lappend((List *) lfirst(cell1), cte);
 				}
 				checkWellFormedSelectStmt(stmt, cstate);
diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index 67eaeb4f3ed..0d506348e1c 100644
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -167,6 +167,65 @@ ERROR:  operator does not exist: text + integer
 LINE 4:     SELECT n+1 FROM t WHERE n < 10
                     ^
 HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+-- Deeply nested WITH caused a list-munging problem in v13
+-- Detection of cross-references and self-references
+WITH RECURSIVE w1(c1) AS
+ (WITH w2(c2) AS
+  (WITH w3(c3) AS
+   (WITH w4(c4) AS
+    (WITH w5(c5) AS
+     (WITH RECURSIVE w6(c6) AS
+      (WITH w6(c6) AS
+       (WITH w8(c8) AS
+        (SELECT 1)
+        SELECT * FROM w8)
+       SELECT * FROM w6)
+      SELECT * FROM w6)
+     SELECT * FROM w5)
+    SELECT * FROM w4)
+   SELECT * FROM w3)
+  SELECT * FROM w2)
+SELECT * FROM w1;
+ c1 
+----
+  1
+(1 row)
+
+-- Detection of invalid self-references
+WITH RECURSIVE outermost(x) AS (
+ SELECT 1
+ UNION (WITH innermost1 AS (
+  SELECT 2
+  UNION (WITH innermost2 AS (
+   SELECT 3
+   UNION (WITH innermost3 AS (
+    SELECT 4
+    UNION (WITH innermost4 AS (
+     SELECT 5
+     UNION (WITH innermost5 AS (
+      SELECT 6
+      UNION (WITH innermost6 AS
+       (SELECT 7)
+       SELECT * FROM innermost6))
+      SELECT * FROM innermost5))
+     SELECT * FROM innermost4))
+    SELECT * FROM innermost3))
+   SELECT * FROM innermost2))
+  SELECT * FROM outermost
+  UNION SELECT * FROM innermost1)
+ )
+ SELECT * FROM outermost ORDER BY 1;
+ x 
+---
+ 1
+ 2
+ 3
+ 4
+ 5
+ 6
+ 7
+(7 rows)
+
 --
 -- Some examples with a tree
 --
diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
index f85645efdee..43cd2e10af3 100644
--- a/src/test/regress/sql/with.sql
+++ b/src/test/regress/sql/with.sql
@@ -87,6 +87,50 @@ UNION ALL
 )
 SELECT n, n IS OF (int) AS is_int FROM t;
 
+-- Deeply nested WITH caused a list-munging problem in v13
+-- Detection of cross-references and self-references
+WITH RECURSIVE w1(c1) AS
+ (WITH w2(c2) AS
+  (WITH w3(c3) AS
+   (WITH w4(c4) AS
+    (WITH w5(c5) AS
+     (WITH RECURSIVE w6(c6) AS
+      (WITH w6(c6) AS
+       (WITH w8(c8) AS
+        (SELECT 1)
+        SELECT * FROM w8)
+       SELECT * FROM w6)
+      SELECT * FROM w6)
+     SELECT * FROM w5)
+    SELECT * FROM w4)
+   SELECT * FROM w3)
+  SELECT * FROM w2)
+SELECT * FROM w1;
+-- Detection of invalid self-references
+WITH RECURSIVE outermost(x) AS (
+ SELECT 1
+ UNION (WITH innermost1 AS (
+  SELECT 2
+  UNION (WITH innermost2 AS (
+   SELECT 3
+   UNION (WITH innermost3 AS (
+    SELECT 4
+    UNION (WITH innermost4 AS (
+     SELECT 5
+     UNION (WITH innermost5 AS (
+      SELECT 6
+      UNION (WITH innermost6 AS
+       (SELECT 7)
+       SELECT * FROM innermost6))
+      SELECT * FROM innermost5))
+     SELECT * FROM innermost4))
+    SELECT * FROM innermost3))
+   SELECT * FROM innermost2))
+  SELECT * FROM outermost
+  UNION SELECT * FROM innermost1)
+ )
+ SELECT * FROM outermost ORDER BY 1;
+
 --
 -- Some examples with a tree
 --