Bug #18895: BIT values cause joins to fail

The Field::eq() considered instances of Field_bit that differ only in 
bit_ptr/bit_ofs equal. This caused equality conditions optimization 
(build_equal_items_for_cond()) to make bad field substitutions that result
in wrong predicates. 
Field_bit requires an overloaded eq() function that checks the bit_ptr/bit_ofs
in addition to Field::eq().


mysql-test/r/select.result:
  Bug #18895: BIT values cause joins to fail
  
  - test case
mysql-test/t/select.test:
  Bug #18895: BIT values cause joins to fail
  
  - test case
sql/field.h:
  Bug #18895: BIT values cause joins to fail
  
  - eq() method overloaded for Field_bit

1 files changed, 20 insertions, 0 deletions

diff --git a/mysql-test/r/select.result b/mysql-test/r/select.result
index 4c1e64cc1cb..e80e8f9ec41 100644
--- a/mysql-test/r/select.result
+++ b/mysql-test/r/select.result
@@ -3359,3 +3359,23 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	PRIMARY,b	b	5	NULL	3	Using where
 1	SIMPLE	t2	ref	c	c	5	test.t1.a	2	Using where
 DROP TABLE t1, t2;
+create table t1 (
+a int unsigned    not null auto_increment primary key,
+b bit             not null,
+c bit             not null
+);
+create table t2 (
+a int unsigned    not null auto_increment primary key,
+b bit             not null,
+c int unsigned    not null,
+d varchar(50)
+);
+insert into t1 (b,c) values (0,1), (0,1);
+insert into t2 (b,c) values (0,1);
+select t1.a, t1.b + 0, t1.c + 0, t2.a, t2.b + 0, t2.c, t2.d
+from t1 left outer join t2 on t1.a = t2.c and t2.b <> 1
+where t1.b <> 1 order by t1.a;
+a	t1.b + 0	t1.c + 0	a	t2.b + 0	c	d
+1	0	1	1	0	1	NULL
+2	0	1	NULL	NULL	NULL	NULL
+drop table t1,t2;