MDEV-14221 Assertion `0' failed in Item::field_type_for_temporal_comparison

mysql-test/r/type_date.result

@@ -843,5 +843,16 @@ Warning	1292	Incorrect datetime value: '1'
 Warning	1292	Incorrect datetime value: '1'
 DROP TABLE t1;
 #
+# MDEV-14221 Assertion `0' failed in Item::field_type_for_temporal_comparison
+#
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1985-05-13'),('1989-12-24');
+SELECT d, COUNT(*) FROM t1 GROUP BY d WITH ROLLUP HAVING CASE d WHEN '2017-05-25' THEN 0 ELSE 1 END;
+d	COUNT(*)
+1985-05-13	1
+1989-12-24	1
+NULL	2
+DROP TABLE t1;
+#
 # End of 10.1 tests
 #

mysql-test/t/type_date.test

@@ -576,6 +576,15 @@ SELECT DATE(a), DATE(b), DATE(c) FROM t1;
 SELECT DATE(COALESCE(a)), DATE(COALESCE(b)), DATE(COALESCE(c)) FROM t1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-14221 Assertion `0' failed in Item::field_type_for_temporal_comparison
+--echo #
+
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1985-05-13'),('1989-12-24');
+SELECT d, COUNT(*) FROM t1 GROUP BY d WITH ROLLUP HAVING CASE d WHEN '2017-05-25' THEN 0 ELSE 1 END;
+DROP TABLE t1;
+
 
 --echo #
 --echo # End of 10.1 tests

sql/item.h

@@ -2581,6 +2581,17 @@ class Item_null_result :public Item_null
   Field *result_field;
   Item_null_result(THD *thd): Item_null(thd), result_field(0) {}
   bool is_result_field() { return result_field != 0; }
+#if MARIADB_VERSION_ID < 100300
+  enum_field_types field_type() const
+  {
+    return result_field->type();
+  }
+#else
+  const Type_handler *type_handler() const
+  {
+    return result_field->type_handler();
+  }
+#endif
   void save_in_result_field(bool no_conversions)
   {
     save_in_field(result_field, no_conversions);