Bug#37601 Cast Is Not Done On Row Comparison

In case of ROW item each compared pair does not
check if argumet collations can be aggregated and
thus appropiriate item conversion does not happen.
The fix is to add the check and convertion for ROW
pairs.


mysql-test/r/row.result:
  test result
mysql-test/t/row.test:
  test case
sql/item.cc:
  added agg_item_set_converter() function which was a part of
  agg_item_charsets() func. The only difference is that
  agg_item_set_converter() checks and converts items 
  using already known collation.
sql/item.h:
  added agg_item_set_converter() function
sql/item_cmpfunc.cc:
  In case of ROW item each compared pair does not
  check if argumet collations can be aggregated and
  thus appropiriate item conversion does not happen.
  The fix is to add the check and convertion for ROW
  pairs.

1 files changed, 14 insertions, 0 deletions

diff --git a/mysql-test/r/row.result b/mysql-test/r/row.result
index 98c79d4bc00..9afb528b6dd 100644
--- a/mysql-test/r/row.result
+++ b/mysql-test/r/row.result
@@ -443,3 +443,17 @@ SELECT ROW(a, 1) IN (SELECT SUM(b), 3) FROM t1 GROUP BY a;
 ROW(a, 1) IN (SELECT SUM(b), 3)
 0
 DROP TABLE t1;
+create table t1 (a varchar(200),
+b int unsigned not null primary key auto_increment)
+default character set 'utf8';
+create table t2 (c varchar(200),
+d int unsigned not null primary key auto_increment)
+default character set 'latin1';
+insert into t1 (a) values('abc');
+insert into t2 (c) values('abc');
+select * from t1,t2 where (a,b) = (c,d);
+a	b	c	d
+abc	1	abc	1
+select host,user from mysql.user where (host,user) = ('localhost','test');
+host	user
+drop table t1,t2;