Bug#59685 crash in String::length with date types

The crash happens because Item_cache which is result
holder for Item_subselect can't correctly convert
a DATETIME value from string to int representation.
The fix is to disable constant item convertion for
subselect(partial rollback of bug52157 fix).


mysql-test/r/type_date.result:
  test case
mysql-test/t/type_date.test:
  test case
sql/item_cmpfunc.cc:
  disable constant item convertion for subselects.

mysql-test/r/type_date.result

@@ -296,6 +296,18 @@ the_date	the_time	the_date	the_time
 2010-01-01	01:01:01	2010-01-01	01:01:01
 DROP TABLE t1;
 DROP VIEW v1;
+#
+# Bug#59685 crash in String::length with date types
+#
+CREATE TABLE t1(a DATE, b YEAR, KEY(a));
+INSERT INTO t1 VALUES ('2011-01-01',2011);
+SELECT b = (SELECT CONVERT(a, DATE) FROM t1 GROUP BY a) FROM t1;
+b = (SELECT CONVERT(a, DATE) FROM t1 GROUP BY a)
+0
+SELECT b = CONVERT((SELECT CONVERT(a, DATE) FROM t1 GROUP BY a), DATE) FROM t1;
+b = CONVERT((SELECT CONVERT(a, DATE) FROM t1 GROUP BY a), DATE)
+0
+DROP TABLE t1;
 End of 5.1 tests
 #
 # Bug #33629: last_day function can return null, but has 'not null'

mysql-test/t/type_date.test

@@ -266,6 +266,18 @@ SELECT * FROM t1 JOIN v1 ON addtime( t1.the_date, t1.the_time ) =
 DROP TABLE t1;
 DROP VIEW v1;
 
+--echo #
+--echo # Bug#59685 crash in String::length with date types
+--echo #
+
+CREATE TABLE t1(a DATE, b YEAR, KEY(a));
+INSERT INTO t1 VALUES ('2011-01-01',2011);
+
+SELECT b = (SELECT CONVERT(a, DATE) FROM t1 GROUP BY a) FROM t1;
+SELECT b = CONVERT((SELECT CONVERT(a, DATE) FROM t1 GROUP BY a), DATE) FROM t1;
+
+DROP TABLE t1;
+
 --echo End of 5.1 tests
 
 --echo #

sql/item_cmpfunc.cc

@@ -403,7 +403,7 @@ static bool convert_constant_item(THD *thd, Item_field *field_item,
   Field *field= field_item->field;
   int result= 0;
 
-  if ((*item)->const_item())
+  if (!(*item)->with_subselect && (*item)->const_item())
   {
     TABLE *table= field->table;
     ulonglong orig_sql_mode= thd->variables.sql_mode;