Fixed bug #19816.

This bug was introduced when the patch resolving the
performance problem 17164 was applied. As a result
of that modification the not_null_tables attributes
were calculated incorrectly for constant OR conditions.
This triggered invalid conversion of outer joins into
inner joins.

mysql-test/r/join_outer.result

@@ -1151,8 +1151,8 @@ EXPLAIN
 SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t2.fkey = t1.id 
 WHERE t1.name LIKE 'A%' OR FALSE;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	PRIMARY,name	name	23	NULL	3	Using where; Using index
-1	SIMPLE	t2	ref	fkey	fkey	5	test.t1.id	1	Using where; Using index
+1	SIMPLE	t2	index	NULL	fkey	5	NULL	5	Using index
+1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.fkey	1	Using where
 DROP TABLE t1,t2;
 DROP VIEW IF EXISTS v1,v2;
 DROP TABLE IF EXISTS t1,t2;
@@ -1176,3 +1176,38 @@ a	b
 3	3
 DROP VIEW v1,v2;
 DROP TABLE t1,t2;
+CREATE TABLE t1 (a int);
+CREATE TABLE t2 (b int);
+INSERT INTO t1 VALUES (1), (2), (3), (4);
+INSERT INTO t2 VALUES (2), (3);
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1);
+a	b
+1	NULL
+2	2
+3	3
+4	NULL
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1 OR 1);
+a	b
+1	NULL
+2	2
+3	3
+4	NULL
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (0 OR 1);
+a	b
+1	NULL
+2	2
+3	3
+4	NULL
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 2=2);
+a	b
+1	NULL
+2	2
+3	3
+4	NULL
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 1=0);
+a	b
+1	NULL
+2	2
+3	3
+4	NULL
+DROP TABLE t1,t2;

mysql-test/t/join_outer.test

@@ -805,3 +805,21 @@ SELECT v1.a, v2. b
 
 DROP VIEW v1,v2;
 DROP TABLE t1,t2;
+
+#
+# Bug 19816: LEFT OUTER JOIN with constant ORed predicates in WHERE clause
+# 
+
+CREATE TABLE t1 (a int);
+CREATE TABLE t2 (b int);
+INSERT INTO t1 VALUES (1), (2), (3), (4);
+INSERT INTO t2 VALUES (2), (3);
+
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1);
+
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1 OR 1);
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (0 OR 1);
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 2=2);
+SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 1=0);
+
+DROP TABLE t1,t2;

sql/item_cmpfunc.cc

@@ -2570,7 +2570,9 @@ Item_cond::fix_fields(THD *thd, Item **ref)
 	(item= *li.ref())->check_cols(1))
       return TRUE; /* purecov: inspected */
     used_tables_cache|=     item->used_tables();
-    if (!item->const_item())
+    if (item->const_item())
+      and_tables_cache= (table_map) 0;
+    else
     {
       tmp_table_map= item->not_null_tables();
       not_null_tables_cache|= tmp_table_map;