MDEV-8680 Wrong result for SELECT..WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a'

The fix for MDEV-8688 fixed MDEV-8680 as well. Just adding a test case.

mysql-test/r/ctype_latin1.result

@@ -8001,5 +8001,23 @@ Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` = '10')
 DROP TABLE t1;
 #
+# MDEV-8680 Wrong result for SELECT..WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a'
+#
+SET NAMES latin1;
+CREATE TABLE t1 (a VARCHAR(10));
+INSERT INTO t1 VALUES ('a'),('A');
+SELECT * FROM t1 WHERE a IN ('a' COLLATE latin1_bin,'b');
+a
+a
+SELECT * FROM t1 WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a';
+a
+a
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 'a') and (`test`.`t1`.`a` in (<cache>(('a' collate latin1_bin)),'b')))
+DROP TABLE t1;
+#
 # End of 10.1 tests
 #

mysql-test/t/ctype_latin1.test

@@ -276,6 +276,17 @@ EXPLAIN EXTENDED SELECT * FROM t1 WHERE a='10' AND IF(a='10',1,0)=1;
 EXPLAIN EXTENDED SELECT * FROM t1 WHERE a='10' AND CASE WHEN a='10' THEN 1 ELSE 0 END;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-8680 Wrong result for SELECT..WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a'
+--echo #
+SET NAMES latin1;
+CREATE TABLE t1 (a VARCHAR(10));
+INSERT INTO t1 VALUES ('a'),('A');
+SELECT * FROM t1 WHERE a IN ('a' COLLATE latin1_bin,'b');
+SELECT * FROM t1 WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a';
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a IN ('a' COLLATE latin1_bin,'b') AND a='a';
+DROP TABLE t1;
+
 --echo #
 --echo # End of 10.1 tests
 --echo #