From dbc84ff96c021f9d8b5968812a416bc6890d015a Mon Sep 17 00:00:00 2001
From: Igor Babaev <igor@askmonty.org>
Date: Fri, 23 Aug 2013 22:17:02 -0700
Subject: [PATCH] Fixed bug mdev-4942. Made sure that degenerate
 conjunctions/disjunctions are obtained from AND/OR conditions.

---
 mysql-test/r/join_outer.result      | 12 ++++++++++++
 mysql-test/r/join_outer_jcl6.result | 12 ++++++++++++
 mysql-test/t/join_outer.test        | 16 ++++++++++++++++
 sql/sql_select.cc                   |  3 ++-
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/join_outer.result b/mysql-test/r/join_outer.result
index 684bfb3836e..b73edc8c52e 100644
--- a/mysql-test/r/join_outer.result
+++ b/mysql-test/r/join_outer.result
@@ -1836,4 +1836,16 @@ SELECT a.* FROM t1 a LEFT JOIN t1 b ON a.id = b.id
 WHERE a.modified > b.modified or b.modified IS NULL;
 id	modified
 DROP TABLE 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;
diff --git a/mysql-test/r/join_outer_jcl6.result b/mysql-test/r/join_outer_jcl6.result
index 4f4c16199e9..a588767d754 100644
--- a/mysql-test/r/join_outer_jcl6.result
+++ b/mysql-test/r/join_outer_jcl6.result
@@ -1847,6 +1847,18 @@ SELECT a.* FROM t1 a LEFT JOIN t1 b ON a.id = b.id
 WHERE a.modified > b.modified or b.modified IS NULL;
 id	modified
 DROP TABLE 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';
diff --git a/mysql-test/t/join_outer.test b/mysql-test/t/join_outer.test
index 8c0ee82e1fa..99f4b1e1315 100644
--- a/mysql-test/t/join_outer.test
+++ b/mysql-test/t/join_outer.test
@@ -1376,4 +1376,20 @@ SELECT a.* FROM t1 a LEFT JOIN t1 b ON a.id = b.id
 
 DROP TABLE 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;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 6b4fc70a353..52c7283b2d9 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -13350,7 +13350,8 @@ 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());