Unexpect error when cast BIT to JSON

[Deardrops]

Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

select cast(B'1' as JSON);

2. What did you expect to see?

mysql> select cast(B'1' as JSON);
+----------------------+
| cast(B'1' as JSON)   |
+----------------------+
| "base64:type15:AQ==" |
+----------------------+
1 row in set (0.00 sec)

mysql> select json_type(cast(B'1' as JSON));
+-------------------------------+
| json_type(cast(B'1' as JSON)) |
+-------------------------------+
| BLOB                          |
+-------------------------------+
1 row in set (0.00 sec)

3. What did you see instead?

mysql> select cast(B'1' as JSON);
ERROR 3140 (22032): Invalid JSON text: The document root must not be followed by other values.

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

Release Version: None
Git Commit Hash: None
Git Branch: None
UTC Build Time: None
GoVersion: None
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false

SIG slack channel

#sig-exec

Score

300

Mentor

• @lzmhhh123

[ghost]

Confirming that I can still reproduce in master:

select cast(B'1' as JSON);
select json_type(cast(B'1' as JSON));

..

mysql> select cast(B'1' as JSON);
ERROR 3140 (22032): Invalid JSON text: The document root must not be followed by other values.
mysql> select json_type(cast(B'1' as JSON));
ERROR 3140 (22032): Invalid JSON text: The document root must not be followed by other values.
mysql> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v4.0.0-beta.2-782-gb72e47e6d
Edition: Community
Git Commit Hash: b72e47e6db8863c08e47714391cf937b0f1c3269
Git Branch: master
UTC Build Time: 2020-07-15 01:26:06
GoVersion: go1.13
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false
1 row in set (0.00 sec)

[XuHuaiyu]

A duplicate issue with #9988.

Not a bug according to this comment