Bug #94612 Wrong results are returned with "group by"

Description:
The to_seconds() function returns the wrong answer with "group by".

How to repeat:
mysql> CREATE TABLE test_table2 (
       id bigint(20) NOT NULL,
       time_test time DEFAULT NULL,
       PRIMARY KEY (id)) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC;
mysql> insert into test_table2 values(1, '15:47:28');
mysql> select to_seconds(timediff(time_test,"19:30:00")) as col1 from test_table2;
+-------------+
| col1        |
+-------------+
| 63719209048 |
+-------------+
1 row in set (0.00 sec)
mysql> select to_seconds(timediff(time_test,"19:30:00")) as col1 from test_table2 group by col1;
+------------+
| col1       |
+------------+
| 2147483647 |
+------------+
1 row in set (0.00 sec)

Hello Lee,

Thank you for the report and test case.

regards,
Umesh

This is still an issue in MySQL 5.7.32. Example:

create table Foo (t datetime);
insert into Foo values('2020-01-01 00:00:01');
insert into Foo values('2020-01-02 00:00:01');
insert into Foo values('2020-01-03 00:00:01');
select t, to_seconds(t) from Foo;
+---------------------+---------------+
| t                   | to_seconds(t) |
+---------------------+---------------+
| 2020-01-01 00:00:01 |   63745056001 |
| 2020-01-02 00:00:01 |   63745142401 |
| 2020-01-03 00:00:01 |   63745228801 |
+---------------------+---------------+
So far so good. Now, use group by:

select t, to_seconds(t) from Foo group by t;
+---------------------+---------------+
| t                   | to_seconds(t) |
+---------------------+---------------+
| 2020-01-01 00:00:01 |    2147483647 |
| 2020-01-02 00:00:01 |    2147483647 |
| 2020-01-03 00:00:01 |    2147483647 |
+---------------------+---------------+

So the to_seconds(t) value for each row becomes 2147483647, which is equal to 2^31-1, i.e. the largest positive value representable by a signed 4-byte integer. So this looks like some kind of data conversion problem inside the MySQL server, in a situation where it ought not occur.

Interestingly, the problem is obviated if instead of to_second(t) we use to_second(max(t)), or max(to_second(t)) (which, theoretically, should produce the same result, since we group on t anyway):

 select t, to_seconds(t), max(t), to_seconds(max(t)), max(to_seconds(t)) from Foo group by t;
+---------------------+---------------+---------------------+--------------------+--------------------+
| t                   | to_seconds(t) | max(t)              | to_seconds(max(t)) | max(to_seconds(t)) |
+---------------------+---------------+---------------------+--------------------+--------------------+
| 2020-01-01 00:00:01 |    2147483647 | 2020-01-01 00:00:01 |        63745056001 |        63745056001 |
| 2020-01-02 00:00:01 |    2147483647 | 2020-01-02 00:00:01 |        63745142401 |        63745142401 |
| 2020-01-03 00:00:01 |    2147483647 | 2020-01-03 00:00:01 |        63745228801 |        63745228801 |
+---------------------+---------------+---------------------+--------------------+-