Bug #21159: Optimizer: wrong result after AND with different data types

Disable const propagation for Item_hex_string.
This must be done because Item_hex_string->val_int() is not
the same as (Item_hex_string->val_str() in BINARY column)->val_int().
We cannot simply disable the replacement in a particular context (
e.g. <bin_col> = <int_col> AND <bin_col> = <hex_string>) since
Items don't know the context they are in and there are functions like 
IF (<hex_string>, 'yes', 'no').
Note that this will disable some valid cases as well 
(e.g. : <bin_col> = <hex_string> AND <bin_col2> = <bin_col>) but 
there's no way to distinguish the valid cases without having the
Item's parent say something like : Item->set_context(Item::STRING_RESULT)
and have all the Items that contain other Items do that consistently.


mysql-test/r/compare.result:
  Bug #21159: Optimizer: wrong result after AND with different data types
   - test case
mysql-test/t/compare.test:
  Bug #21159: Optimizer: wrong result after AND with different data types
   - test case
sql/sql_select.cc:
  Bug #21159: Optimizer: wrong result after AND with different data types
   - disable const propagation for Item_hex_string.

1 files changed, 7 insertions, 0 deletions

diff --git a/mysql-test/r/compare.result b/mysql-test/r/compare.result
index 6f667aabac0..da0ca8ddba1 100644
--- a/mysql-test/r/compare.result
+++ b/mysql-test/r/compare.result
@@ -42,3 +42,10 @@ CHAR(31) = ''	'' = CHAR(31)
 SELECT CHAR(30) = '', '' = CHAR(30);
 CHAR(30) = ''	'' = CHAR(30)
 0	0
+create table t1 (a tinyint(1),b binary(1));
+insert into t1 values (0x01,0x01);
+select * from t1 where a=b;
+a	b
+select * from t1 where a=b and b=0x01;
+a	b
+drop table if exists t1;