Merge fix for MDEV-4942, 5.3->5.5

mysql-test/r/join_outer.result

@@ -2138,4 +2138,16 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t0.a	1	Using index
 drop table t0, t1;
+#
+# Bug mdev-4942: LEFT JOIN with conjunctive 
+#                <non-nullable datetime field> IS NULL in WHERE 
+#                causes an assert failure  
+#
+CREATE TABLE t1 ( i1 int, d1 date );
+INSERT INTO t1 VALUES (1,'2001-06-26'), (2,'2000-11-16');
+CREATE TABLE t2 ( i2 int, d2 date NOT NULL );
+INSERT INTO t2 VALUES (3,'2000-03-06'), (4,'2007-09-25');
+SELECT * FROM t1 LEFT JOIN t2 ON i1 = i2 WHERE d1 IS NULL AND d2 IS NULL;
+i1	d1	i2	d2
+DROP TABLE t1,t2;
 SET optimizer_switch=@save_optimizer_switch;

mysql-test/r/join_outer_jcl6.result

@@ -2149,6 +2149,18 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t0.a	1	Using index
 drop table t0, t1;
+#
+# Bug mdev-4942: LEFT JOIN with conjunctive 
+#                <non-nullable datetime field> IS NULL in WHERE 
+#                causes an assert failure  
+#
+CREATE TABLE t1 ( i1 int, d1 date );
+INSERT INTO t1 VALUES (1,'2001-06-26'), (2,'2000-11-16');
+CREATE TABLE t2 ( i2 int, d2 date NOT NULL );
+INSERT INTO t2 VALUES (3,'2000-03-06'), (4,'2007-09-25');
+SELECT * FROM t1 LEFT JOIN t2 ON i1 = i2 WHERE d1 IS NULL AND d2 IS NULL;
+i1	d1	i2	d2
+DROP TABLE t1,t2;
 SET optimizer_switch=@save_optimizer_switch;
 set join_cache_level=default;
 show variables like 'join_cache_level';

mysql-test/t/join_outer.test

@@ -1687,4 +1687,20 @@ explain select * from t1 left join t0 on t0.a=t1.pk where t0.person_id='fooo' or
 drop table t0, t1;
 
 
+--echo #
+--echo # Bug mdev-4942: LEFT JOIN with conjunctive 
+--echo #                <non-nullable datetime field> IS NULL in WHERE 
+--echo #                causes an assert failure  
+--echo #
+
+CREATE TABLE t1 ( i1 int, d1 date );
+INSERT INTO t1 VALUES (1,'2001-06-26'), (2,'2000-11-16');
+
+CREATE TABLE t2 ( i2 int, d2 date NOT NULL );
+INSERT INTO t2 VALUES (3,'2000-03-06'), (4,'2007-09-25');
+
+SELECT * FROM t1 LEFT JOIN t2 ON i1 = i2 WHERE d1 IS NULL AND d2 IS NULL;
+
+DROP TABLE t1,t2;
+
 SET optimizer_switch=@save_optimizer_switch;

sql/sql_select.cc

@@ -13642,7 +13642,8 @@ internal_remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
           In these cases the disjunct/conjunct must be merged into the
           argument list of cond.
 	*/
-        if (new_item->type() == Item::COND_ITEM)
+        if (new_item->type() == Item::COND_ITEM &&
+            item->type() == Item::COND_ITEM)
         {
           DBUG_ASSERT(((Item_cond *) cond)->functype() == 
                       ((Item_cond *) new_item)->functype());