MDEV-30248 Infinite sequence of recursive calls when processing embedded CTE

This patch fixes the patch for bug MDEV-30248 that unsatisfactorily
resolved the problem of resolution of references to CTE. In some cases
when such a reference has the same table name as the name of one of
CTEs containing this reference the reference could be resolved incorrectly
that led to an invalid select tree where units could be mutually dependent.
This in its turn could lead to an infinite sequence of recursive calls or
to falls into infinite loops.

The patch also removes LEX::resolve_references_to_cte_in_hanging_cte() as
with the new code for resolution of CTE references the call of this
function is not needed anymore.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/mysql-test/main/cte_recursive.test b/mysql-test/main/cte_recursive.test
index 270a5023d31..f4dafbf9294 100644
--- a/mysql-test/main/cte_recursive.test
+++ b/mysql-test/main/cte_recursive.test
@@ -3872,5 +3872,128 @@ select * from cte;
 drop table t1,t2,t3,x;
 
 --echo #
+--echo # MDEV-30248: Embedded non-recursive CTE referring to base table 'x'
+--echo #             within a CTE with name 'x' used in a subquery from
+--echo #             select list of another CTE
+--echo #
+
+CREATE TABLE x (a int) ENGINE=MyISAM;
+INSERT INTO x VALUES (3),(7),(1);
+CREATE TABLE t1 (b int) ENGINE=MYISAM;
+INSERT INTO t1 VALUES (1);
+
+let $q1=
+WITH cte AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH x AS (SELECT a FROM x AS t) SELECT 1 AS b)
+      SELECT b FROM x AS r
+    ) AS c
+)
+SELECT cte.c FROM cte;
+eval $q1;
+
+let $q2=
+WITH cte AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH x AS (SELECT a FROM x AS t) SELECT b FROM t1)
+      SELECT b FROM x AS r
+    ) AS c
+)
+SELECT cte.c FROM cte;
+eval $q2;
+
+let $q3=
+WITH cte AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH y AS (SELECT a FROM x AS t) SELECT b FROM t1)
+      SELECT b FROM x AS r
+    ) AS c
+)
+SELECT cte.c FROM cte;
+eval $q3;
+
+
+let $q4=
+WITH cte AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH y(b) AS (SELECT a FROM x AS t LIMIT 1) SELECT b FROM y)
+      SELECT b FROM x AS r
+    ) AS c
+)
+SELECT cte.c FROM cte;
+eval $q4;
+
+let $q5=
+WITH cte AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH x(b) AS (SELECT a FROM x AS t LIMIT 1) SELECT b FROM x)
+      SELECT b FROM x AS r
+    ) AS c
+)
+SELECT cte.c FROM cte;
+eval $q5;
+
+let $q6=
+WITH x AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH x AS (SELECT a FROM x AS t) SELECT 1 AS b)
+      SELECT b FROM x AS r
+    ) AS c
+)
+SELECT x.c from x;
+eval $q6;
+
+let $q7=
+WITH cte AS
+(
+  SELECT
+    (
+      WITH x AS
+      (WITH x AS (SELECT a FROM x AS t) SELECT 2 AS b)
+      SELECT r1.b FROM x AS r1, x AS r2 WHERE r1.b=r2.b
+    ) AS c
+)
+SELECT cte.c from cte;
+eval $q7;
+
+
+DROP TABLE x;
+
+--ERROR ER_NO_SUCH_TABLE
+eval $q1;
+--ERROR ER_NO_SUCH_TABLE
+eval $q2;
+--ERROR ER_NO_SUCH_TABLE
+eval $q3;
+--ERROR ER_NO_SUCH_TABLE
+eval $q4;
+--ERROR ER_NO_SUCH_TABLE
+eval $q5;
+--ERROR ER_NO_SUCH_TABLE
+eval $q6;
+--ERROR ER_NO_SUCH_TABLE
+eval $q7;
+
+DROP TABLE t1;
+
+--echo #
 --echo # End of 10.3 tests
 --echo #