MDEV-23838 Possibly wrong result or Assertion `0' failed in Item_func_round::native_op

Change history in the affected code:

- Since 10.4.8 (MDEV-20397 and MDEV-23311), functions ROUND(), CEILING(),
  FLOOR() return a TIME value for a TIME input.
- Since 10.4.14 (MDEV-23525), MIN() and MAX() calculate a result for a TIME
  input using val_native() rather than val_str().

Problem:

The patch for MDEV-23525 did not take into account combinations like
MIN(ROUND(time)), MAX(FLOOR(time)), etc.

MIN() and MAX() with ROUND(time), CEILING(time), FLOOR(time) as an argument
call the method val_native() of the undelying classes Item_func_round and
Item_func_int_val. However these classes implemented the method val_native()
as DBUG_ASSERT(0).

Fix:

This patch adds a TIME-specific code inside:
- Item_func_round::val_native()
- Item_func_int_val::val_native()
still with DBUG_ASSERT(0) for all other data types,
as other data types do not call val_native() of these classes.

We'll need a more generic solition eventualy, e.g.
turn Item_func_round and Item_func_int_val into Item_handled_func.
However, this change would be too risky for 10.4 at this point.

mysql-test/main/type_time.result

@@ -2446,5 +2446,49 @@ DROP TABLE t1;
 SET @@time_zone=DEFAULT;
 SET TIMESTAMP=DEFAULT;
 #
+# MDEV-23838 Possibly wrong result or Assertion `0' failed in Item_func_round::native_op
+#
+CREATE TABLE t1 (a TIME, b INT);
+INSERT INTO t1 VALUES ('07:26:24',NULL),('23:55:04',NULL);
+SELECT MAX(ROUND(a, 0)) FROM t1 GROUP BY 1 << b;
+MAX(ROUND(a, 0))
+23:55:04
+DROP TABLE t1;
+CREATE TABLE t1 (a TIME(6), b INT);
+INSERT INTO t1 VALUES ('07:26:24.12',NULL),('23:55:04.34',NULL);
+SELECT MAX(ROUND(a, 2)) FROM t1 GROUP BY 1 << b;
+MAX(ROUND(a, 2))
+23:55:04.34
+DROP TABLE t1;
+SET sql_mode='';
+CREATE TABLE t1 (a TIME);
+INSERT INTO t1 VALUES (0),(0);
+SELECT MAX(ROUND (a,a)) FROM t1 GROUP BY a;
+MAX(ROUND (a,a))
+00:00:00
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (a TIME, b INT);
+INSERT INTO t1 VALUES ('07:26:24',1),('23:55:04',1);
+SELECT MIN(CEILING(a)), MAX(CEILING(a)) FROM t1 GROUP BY b;
+MIN(CEILING(a))	MAX(CEILING(a))
+07:26:24	23:55:04
+SELECT MIN(FLOOR(a)), MAX(FLOOR(a)) FROM t1 GROUP BY b;
+MIN(FLOOR(a))	MAX(FLOOR(a))
+07:26:24	23:55:04
+DROP TABLE t1;
+CREATE TABLE t1 (a TIME(6), b INT);
+INSERT INTO t1 VALUES ('00:00:00.5',1),('00:01:00.5',1);
+INSERT INTO t1 VALUES ('-00:00:00.5',2),('-00:01:00.5',2);
+SELECT MIN(CEILING(a)), MAX(CEILING(a)) FROM t1 GROUP BY b;
+MIN(CEILING(a))	MAX(CEILING(a))
+00:00:01	00:01:01
+-00:01:00	00:00:00
+SELECT MIN(FLOOR(a)), MAX(FLOOR(a)) FROM t1 GROUP BY b;
+MIN(FLOOR(a))	MAX(FLOOR(a))
+00:00:00	00:01:00
+-00:01:01	-00:00:01
+DROP TABLE t1;
+#
 # End of 10.4 tests
 #

mysql-test/main/type_time.test

@@ -1585,6 +1585,41 @@ SET @@time_zone=DEFAULT;
 SET TIMESTAMP=DEFAULT;
 
 
+--echo #
+--echo # MDEV-23838 Possibly wrong result or Assertion `0' failed in Item_func_round::native_op
+--echo #
+
+CREATE TABLE t1 (a TIME, b INT);
+INSERT INTO t1 VALUES ('07:26:24',NULL),('23:55:04',NULL);
+SELECT MAX(ROUND(a, 0)) FROM t1 GROUP BY 1 << b;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a TIME(6), b INT);
+INSERT INTO t1 VALUES ('07:26:24.12',NULL),('23:55:04.34',NULL);
+SELECT MAX(ROUND(a, 2)) FROM t1 GROUP BY 1 << b;
+DROP TABLE t1;
+
+SET sql_mode='';
+CREATE TABLE t1 (a TIME);
+INSERT INTO t1 VALUES (0),(0);
+SELECT MAX(ROUND (a,a)) FROM t1 GROUP BY a;
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+CREATE TABLE t1 (a TIME, b INT);
+INSERT INTO t1 VALUES ('07:26:24',1),('23:55:04',1);
+SELECT MIN(CEILING(a)), MAX(CEILING(a)) FROM t1 GROUP BY b;
+SELECT MIN(FLOOR(a)), MAX(FLOOR(a)) FROM t1 GROUP BY b;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a TIME(6), b INT);
+INSERT INTO t1 VALUES ('00:00:00.5',1),('00:01:00.5',1);
+INSERT INTO t1 VALUES ('-00:00:00.5',2),('-00:01:00.5',2);
+SELECT MIN(CEILING(a)), MAX(CEILING(a)) FROM t1 GROUP BY b;
+SELECT MIN(FLOOR(a)), MAX(FLOOR(a)) FROM t1 GROUP BY b;
+DROP TABLE t1;
+
+
 --echo #
 --echo # End of 10.4 tests
 --echo #

sql/item_func.cc

@@ -2233,6 +2233,16 @@ bool Item_func_int_val::fix_length_and_dec()
 }
 
 
+bool Item_func_int_val::native_op(THD *thd, Native *to)
+{
+  // TODO: turn Item_func_int_val into Item_handled_func eventually.
+  if (type_handler()->mysql_timestamp_type() == MYSQL_TIMESTAMP_TIME)
+    return Time(thd, this).to_native(to, decimals);
+  DBUG_ASSERT(0);
+  return true;
+}
+
+
 longlong Item_func_ceiling::int_op()
 {
   switch (args[0]->result_type()) {
@@ -2661,6 +2671,16 @@ bool Item_func_round::date_op(THD *thd, MYSQL_TIME *to, date_mode_t fuzzydate)
 }
 
 
+bool Item_func_round::native_op(THD *thd, Native *to)
+{
+  // TODO: turn Item_func_round into Item_handled_func eventually.
+  if (type_handler()->mysql_timestamp_type() == MYSQL_TIMESTAMP_TIME)
+    return Time(thd, this).to_native(to, decimals);
+  DBUG_ASSERT(0);
+  return true;
+}
+
+
 void Item_func_rand::seed_random(Item *arg)
 {
   /*

sql/item_func.h

@@ -1748,11 +1748,7 @@ class Item_func_int_val :public Item_func_hybrid_field_type
   }
   bool fix_length_and_dec();
   String *str_op(String *str) { DBUG_ASSERT(0); return 0; }
-  bool native_op(THD *thd, Native *to)
-  {
-    DBUG_ASSERT(0);
-    return true;
-  }
+  bool native_op(THD *thd, Native *to);
 };
 
 
@@ -1804,11 +1800,7 @@ class Item_func_round :public Item_func_hybrid_field_type
   my_decimal *decimal_op(my_decimal *);
   bool date_op(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate);
   bool time_op(THD *thd, MYSQL_TIME *ltime);
-  bool native_op(THD *thd, Native *to)
-  {
-    DBUG_ASSERT(0);
-    return true;
-  }
+  bool native_op(THD *thd, Native *to);
   String *str_op(String *str)
   {
     DBUG_ASSERT(0);