No warning for invalid usage of function LN()

[zhangysh1995]

Bug Report

LN(0) should result in a warning or an error

1. Minimal reproduce step (Required)

select LN(0);

2. What did you expect to see? (Required)

A warning is raised or the error is returned.

-- MySQL 5.7
mysql> select LN(0);
+-------+
| LN(0) |
+-------+
|  NULL |
+-------+
1 row in set, 1 warning (0.00 sec)

mysql> show warnings;
+---------+------+--------------------------------+
| Level   | Code | Message                        |
+---------+------+--------------------------------+
| Warning | 3020 | Invalid argument for logarithm |
+---------+------+--------------------------------+
1 row in set (0.00 sec)

3. What did you see instead (Required)

mysql> select LN(0);
+-------+
| LN(0) |
+-------+
|  NULL |
+-------+
1 row in set (0.00 sec)

4. Affected version (Required)

commit 4e74d40392e9b81f2a90cbc2f7777fd35f87b2e7 (HEAD -> master, origin/master, origin/HEAD)
Author: Arenatlx <ailinsilence4@gmail.com>
Date:   Fri Jun 12 16:58:00 2020 +0800

5. Root Cause Analysis

[g1eny0ung]

/label component/expression