Split table index on non-int clustered index should not be allowed

[pcqz]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

mysql> CREATE TABLE `test` (`id` varchar(10) NOT NULL, primary key (`id`) /*T![clustered_index] CLUSTERED */ );
Query OK, 0 rows affected (0.08 sec)

mysql> split table test index `primary` between (0) and (1000) regions 2;
+--------------------+----------------------+
| TOTAL_SPLIT_REGION | SCATTER_FINISH_RATIO |
+--------------------+----------------------+
|                  2 |                    1 |
+--------------------+----------------------+
1 row in set (0.21 sec)

mysql> show table test regions;
+-----------+------------------------------+------------------------------+-----------+-----------------+-------+------------+---------------+------------+----------------------+------------------+------------------------+------------------+
| REGION_ID | START_KEY                    | END_KEY                      | LEADER_ID | LEADER_STORE_ID | PEERS | SCATTERING | WRITTEN_BYTES | READ_BYTES | APPROXIMATE_SIZE(MB) | APPROXIMATE_KEYS | SCHEDULING_CONSTRAINTS | SCHEDULING_STATE |
+-----------+------------------------------+------------------------------+-----------+-----------------+-------+------------+---------------+------------+----------------------+------------------+------------------------+------------------+
|        14 | t_110_i_2_                   | t_281474976710649_           |        15 |               1 | 15    |          0 |           217 |          0 |                    1 |                0 |                        |                  |
|       664 | t_110_                       | t_110_i_1_013098181800000000 |       665 |               1 | 665   |          0 |             0 |          0 |                    1 |                0 |                        |                  |
|       666 | t_110_i_1_013098181800000000 | t_110_i_2_                   |       667 |               1 | 667   |          0 |             0 |          0 |                    1 |                0 |                        |                  |
+-----------+------------------------------+------------------------------+-----------+-----------------+-------+------------+---------------+------------+----------------------+------------------+------------------------+------------------+
3 rows in set (0.01 sec)

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

The error "ERROR 1176 (42000): Key 'primary' doesn't exist in table 'test'" should be reported like int type clustered index.

3. What did you see instead (Required)

Split table index is executed without error.

4. What is your TiDB version? (Required)

v7.1.1

[pcqz]

/found gs