wrong results when CASE...WHEN function along with float argument

[SunRunAway]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

2. What did you expect to see?

W/ MySQL 5.7

mysql> select case when 0.1 then 1 else 2 end;
+---------------------------------+
| case when 0.1 then 1 else 2 end |
+---------------------------------+
|                               1 |
+---------------------------------+
1 row in set (0.00 sec)

3. What did you see instead?

W/ TiDB,

mysql> select case when 0.1 then 1 else 2 end;
+---------------------------------+
| case when 0.1 then 1 else 2 end |
+---------------------------------+
|                               2 |
+---------------------------------+
1 row in set (0.00 sec)

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

b504d37

[SunRunAway]

@lance6716
Would you like to take a look?

[lance6716]

@lance6716
Would you like to take a look?

OK, since CASE function has a seperated issue, I'm going to let #15016 close #11601