_utf8 not supported

[jackysp]

Please answer these questions before submitting your issue. Thanks!

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

select left(_utf8 0xD0B0D0B1D0B2,1) 

2. What did you expect to see?

mysql> select left(_utf8 0xD0B0D0B1D0B2,1);
+------------------------------+
| left(_utf8 0xD0B0D0B1D0B2,1) |
+------------------------------+
| а                            |
+------------------------------+
1 row in set (0.01 sec)

3. What did you see instead?

mysql> select left(_utf8 0xD0B0D0B1D0B2,1);
ERROR 1105 (HY000): line 0 column 32 near ",1)" (total length 35)

4. What version of TiDB are you using (tidb-server -V)?

[morgo]

Confirming that this issue can still be reproduced:

mysql57> select left(_utf8 0xD0B0D0B1D0B2,1);
+------------------------------+
| left(_utf8 0xD0B0D0B1D0B2,1) |
+------------------------------+
| а                            |
+------------------------------+
1 row in set (0.00 sec)

tidb> select left(_utf8 0xD0B0D0B1D0B2,1);
ERROR 1105 (HY000): line 1 column 32 near ",1)" (total length 35)
mysql> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v2.1.0-rc.3-219-g1e0876fe8-dirty
Git Commit Hash: 1e0876fe810a832721aac52275dd2b7792fd2892
Git Branch: flush
UTC Build Time: 2018-11-24 01:12:47
GoVersion: go version go1.11 linux/amd64
Race Enabled: false
TiKV Min Version: 2.1.0-alpha.1-ff3dd160846b7d1aed9079c389fc188f7f5ea13e
Check Table Before Drop: false
1 row in set (0.00 sec)

[ghost]

Still present in master:

..
mysql> SELECT tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v4.0.0-beta.2-852-g1e7454c81
Edition: Community
Git Commit Hash: 1e7454c81d1f4fae464e835d1a4023a911cfa87b
Git Branch: master
UTC Build Time: 2020-07-28 01:36:23
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)

mysql> select left(_utf8 0xD0B0D0B1D0B2,1) 
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 32 near "0xD0B0D0B1D0B2,1)" 

[tangenta]

Fixed by pingcap/parser#926.