There is a problem adding an index to a generated column with an expression error.

[zimulala]

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.

create table t(
  y year NOT NULL DEFAULT '2155'
)ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
insert into t values();
ALTER TABLE t ADD COLUMN y1 year as (y + 2);
ALTER TABLE t ADD INDEX idx_y(y1);

2. What did you expect to see?

mysql> create table t(
    ->   y year NOT NULL DEFAULT '2155'
    -> )ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
Query OK, 0 rows affected (0.02 sec)

mysql> insert into t values();
Query OK, 1 row affected (0.00 sec)

mysql> ALTER TABLE t ADD COLUMN y1 year as (y + 2);
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> ALTER TABLE t ADD INDEX idx_y(y1);
ERROR 1264 (22003): Out of range value for column 'y1' at row 1

3. What did you see instead?
   Executing this statement of ALTER TABLE t ADD INDEX idx_y(y1); will get stuck.

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
   Release Version: v3.0.0-beta-18-g7648317da
   Git Commit Hash: 7648317
   Git Branch: master