MDEV-14217 [db crash] Recursive CTE when SELECT includes new field

mysql-test/r/cte_recursive.result

@@ -2881,3 +2881,26 @@ f
 2
 set standard_compliant_cte=default;
 DROP TABLE t;
+#
+# MDEV-14217 [db crash] Recursive CTE when SELECT includes new field
+#
+CREATE TEMPORARY TABLE a_tbl (
+a VARCHAR(33) PRIMARY KEY,
+b VARCHAR(33)
+);
+INSERT INTO a_tbl VALUES ('block0', 'block0'), ('block1', NULL);
+WITH RECURSIVE Q0 AS (
+SELECT T0.a, T0.b, 5
+FROM a_tbl T0
+WHERE b IS NULL
+UNION ALL
+SELECT T1.a, T1.b
+FROM Q0
+JOIN a_tbl T1
+ON T1.a=Q0.a
+) SELECT distinct(Q0.a), Q0.b
+FROM Q0;
+ERROR 21000: The used SELECT statements have a different number of columns
+DROP TABLE a_tbl;
+WITH RECURSIVE x AS (SELECT 1,2 UNION ALL SELECT 1 FROM x) SELECT * FROM x;
+ERROR 21000: The used SELECT statements have a different number of columns

mysql-test/t/cte_recursive.test

@@ -1928,3 +1928,31 @@ set standard_compliant_cte=default;
 
 DROP TABLE t;
 
+
+--echo #
+--echo # MDEV-14217 [db crash] Recursive CTE when SELECT includes new field
+--echo #
+
+CREATE TEMPORARY TABLE a_tbl (
+  a VARCHAR(33) PRIMARY KEY,
+  b VARCHAR(33)
+);
+
+INSERT INTO a_tbl VALUES ('block0', 'block0'), ('block1', NULL);
+
+--error ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT
+WITH RECURSIVE Q0 AS (
+  SELECT T0.a, T0.b, 5
+  FROM a_tbl T0
+  WHERE b IS NULL
+  UNION ALL
+  SELECT T1.a, T1.b
+  FROM Q0
+  JOIN a_tbl T1
+  ON T1.a=Q0.a
+) SELECT distinct(Q0.a), Q0.b
+  FROM Q0;
+DROP TABLE a_tbl;
+
+--error ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT
+WITH RECURSIVE x AS (SELECT 1,2 UNION ALL SELECT 1 FROM x) SELECT * FROM x;

sql/sql_union.cc

@@ -770,13 +770,7 @@ bool st_select_lex_unit::join_union_type_handlers(THD *thd_arg,
         holders[pos].set_handler(item_type_handler);
       else
       {
-        if (first_sl->item_list.elements != sl->item_list.elements)
-        {
-          my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
-                     ER_THD(thd_arg, ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT),
-                     MYF(0));
-          DBUG_RETURN(true);
-        }
+        DBUG_ASSERT(first_sl->item_list.elements == sl->item_list.elements);
         if (holders[pos].aggregate_for_result(item_type_handler))
         {
           my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0),
@@ -1024,6 +1018,16 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
           goto err;
       }
     }
+    else
+    {
+      if (first_sl->item_list.elements != sl->item_list.elements)
+      {
+        my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
+                   ER_THD(thd_arg, ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT),
+                   MYF(0));
+        goto err;
+      }
+    }
     if (is_recursive)
     {
       if (!with_element->is_anchor(sl))