Fixed bugs: mdev-13780 CTE not found, mdev-14184 recursive CTE not found

The support of embedded CTEs was not correct in the cases when
embedded CTEs were used multiple times. The problems occurred with
both non-recursive (bug mdev-13780) and recursive (bug mdev-14184)
embedded CTEs.

mysql-test/r/cte_nonrecursive.result

@@ -1079,3 +1079,52 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 3	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	3	Using where; Using join buffer (flat, BNL join)
 NULL	UNION RESULT	<union1,4>	ALL	NULL	NULL	NULL	NULL	NULL	
 DROP TABLE t1,t2;
+#
+# MDEV-13780: tower of embedding CTEs with multiple usage of them
+#
+create table t1 (a int);
+insert into t1 values (3), (2), (4), (7), (1), (2), (5);
+with cte_e as
+(
+with cte_o as
+(
+with cte_i as (select * from t1 where a < 7)
+select * from cte_i where a > 1
+)
+select * from cte_o as cto_o1 where a < 3
+union
+select * from cte_o as cto_o2 where a > 4
+)
+select * from cte_e as cte_e1 where a > 1
+union
+select * from cte_e as cte_e2;
+a
+2
+5
+explain extended with cte_e as
+(
+with cte_o as
+(
+with cte_i as (select * from t1 where a < 7)
+select * from cte_i where a > 1
+)
+select * from cte_o as cto_o1 where a < 3
+union
+select * from cte_o as cto_o2 where a > 4
+)
+select * from cte_e as cte_e1 where a > 1
+union
+select * from cte_e as cte_e2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	14	100.00	Using where
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	7	100.00	Using where
+5	UNION	t1	ALL	NULL	NULL	NULL	NULL	7	100.00	Using where
+NULL	UNION RESULT	<union2,5>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
+6	UNION	<derived9>	ALL	NULL	NULL	NULL	NULL	14	100.00	
+9	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	7	100.00	Using where
+12	UNION	t1	ALL	NULL	NULL	NULL	NULL	7	100.00	Using where
+NULL	UNION RESULT	<union9,12>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
+NULL	UNION RESULT	<union1,6>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
+Warnings:
+Note	1003	with cte_e as (with cte_o as (with cte_i as (select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 7)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 1)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 3 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 and `test`.`t1`.`a` > 1 union select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 4 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 and `test`.`t1`.`a` > 1)select `cte_e1`.`a` AS `a` from `cte_e` `cte_e1` where `cte_e1`.`a` > 1 union select `cte_e2`.`a` AS `a` from `cte_e` `cte_e2`
+drop table t1;

mysql-test/r/cte_recursive.result

@@ -2875,3 +2875,25 @@ f
 2
 set standard_compliant_cte=default;
 DROP TABLE t;
+#
+# mdev-14184: recursive CTE embedded into CTE with multiple references 
+#
+WITH
+cte1 AS (
+SELECT n FROM (
+WITH RECURSIVE rec_cte(n) AS (
+SELECT 1 as n1
+UNION ALL
+SELECT n+1 as n2 FROM rec_cte WHERE n < 3
+) SELECT n FROM rec_cte
+) AS X
+),
+cte2 as (
+SELECT 2 FROM cte1
+)
+SELECT *
+FROM cte1;
+n
+1
+2
+3

mysql-test/t/cte_nonrecursive.test

@@ -743,3 +743,31 @@ eval $q;
 eval explain $q;
 
 DROP TABLE t1,t2;
+
+--echo #
+--echo # MDEV-13780: tower of embedding CTEs with multiple usage of them
+--echo #
+
+create table t1 (a int);
+insert into t1 values (3), (2), (4), (7), (1), (2), (5);
+
+let $q=
+with cte_e as
+(
+  with cte_o as
+  (
+    with cte_i as (select * from t1 where a < 7)
+    select * from cte_i where a > 1
+  )
+  select * from cte_o as cto_o1 where a < 3
+  union
+  select * from cte_o as cto_o2 where a > 4
+)
+select * from cte_e as cte_e1 where a > 1
+union
+select * from cte_e as cte_e2;
+
+eval $q;
+eval explain extended $q;
+
+drop table t1;

mysql-test/t/cte_recursive.test

@@ -1928,3 +1928,22 @@ set standard_compliant_cte=default;
 
 DROP TABLE t;
 
+--echo #
+--echo # mdev-14184: recursive CTE embedded into CTE with multiple references 
+--echo #
+
+WITH
+cte1 AS (
+  SELECT n FROM (
+    WITH RECURSIVE rec_cte(n) AS (
+      SELECT 1 as n1
+      UNION ALL
+      SELECT n+1 as n2 FROM rec_cte WHERE n < 3
+    ) SELECT n FROM rec_cte
+  ) AS X
+),
+cte2 as (
+ SELECT 2 FROM cte1
+)
+SELECT *
+FROM cte1;

sql/sql_cte.cc

@@ -349,7 +349,10 @@ void With_element::check_dependencies_in_select(st_select_lex *sl,
   /* Now look for the dependencies in the subqueries of sl */
   st_select_lex_unit *inner_unit= sl->first_inner_unit();
   for (; inner_unit; inner_unit= inner_unit->next_unit())
+  {
+    if (!inner_unit->with_element)
       check_dependencies_in_unit(inner_unit, ctxt, in_subq, dep_map);
+  }
 }
 
 
@@ -838,7 +841,6 @@ st_select_lex_unit *With_element::clone_parsed_spec(THD *thd,
     with_table->next_global= spec_tables;
   }
   res= &lex->unit;
-  res->set_with_clause(owner);
   
   lex->unit.include_down(with_table->select_lex);
   lex->unit.set_slave(with_select); 
@@ -847,6 +849,8 @@ st_select_lex_unit *With_element::clone_parsed_spec(THD *thd,
 		      insert_chain_before(
 			(st_select_lex_node **) &(old_lex->all_selects_list),
                         with_select));
+  if (check_dependencies_in_with_clauses(lex->with_clauses_list))
+    res= NULL;
   lex_end(lex);
 err:
   if (arena)
@@ -990,14 +994,18 @@ With_element *st_select_lex::find_table_def_in_with_clauses(TABLE_LIST *table)
       and it was unsuccesful. Yet for units cloned from the spec it has not 
       been done yet.
     */
-    if (with_elem && sl->master_unit() == with_elem->spec)
+    With_clause *attached_with_clause=sl->get_with_clause();
+    if (attached_with_clause &&
+        (found= attached_with_clause->find_table_def(table, NULL)))
       break;
-    With_clause *with_clause=sl->get_with_clause();
-    if (with_clause)
+    if (with_elem)
     {
-      With_element *barrier= with_clause->with_recursive ? NULL : with_elem;
-      if ((found= with_clause->find_table_def(table, barrier)))
+      With_clause *containing_with_clause= with_elem->get_owner();
+      With_element *barrier= containing_with_clause->with_recursive ?
+                               NULL : with_elem;
+      if ((found= containing_with_clause->find_table_def(table, barrier)))
         break;
+      sl= sl->master_unit()->outer_select(); 
     }
     master_unit= sl->master_unit();
     /* Do not look for the table's definition beyond the scope of the view */