NO_BACKSLASH_ESCAPES doesn't work for DDL in generated column

[YangKeao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

SET SQL_MODE='NO_BACKSLASH_ESCAPES'; CREATE TABLE t1 (s VARCHAR(10), g VARCHAR(20) AS (CONCAT(s, '\\\\c'))); INSERT INTO t1 (s) VALUES ('a\\\\b'); SELECT * FROM t1 ORDER BY s; DROP TABLE t1; SET SQL_MODE=DEFAULT;

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

mysql> SET SQL_MODE='NO_BACKSLASH_ESCAPES'; CREATE TABLE t1 (s VARCHAR(10), g VARCHAR(20) AS (CONCAT(s, '\\\\c'))); INSERT INTO t1 (s) VALUES ('a\\\\b'); SELECT * FROM t1 ORDER BY s; DROP TABLE t1; SET SQL_MODE=DEFAULT;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.06 sec)

Query OK, 1 row affected (0.01 sec)

+--------+-----------------+
| s      | g               |
+--------+-----------------+
| a\\\\b | a\\\\b\\\\\\\\c |
+--------+-----------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

Query OK, 0 rows affected (0.00 sec)

3. What did you see instead (Required)

mysql> SET SQL_MODE='NO_BACKSLASH_ESCAPES'; CREATE TABLE t1 (s VARCHAR(10), g VARCHAR(20) AS (CONCAT(s, '\\\\c'))); INSERT INTO t1 (s) VALUES ('a\\\\b'); SELECT * FROM t1 ORDER BY s; DROP TABLE t1; SET SQL_MODE=DEFAULT;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.05 sec)

Query OK, 1 row affected (0.01 sec)

+--------+-------------+
| s      | g           |
+--------+-------------+
| a\\\\b | a\\\\b\\\\c |
+--------+-------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.08 sec)

Query OK, 0 rows affected (0.00 sec)

4. What is your TiDB version? (Required)