DEFAULT on an optional-length string column is silently truncated to the empty string

CREATE TABLE t1 (a VARCHAR DEFAULT 'x');

# shows `a` text DEFAULT '' , but expected DEFAULT 'x' in CREATE TABLE statement

SHOW CREATE TABLE t1;       

INSERT INTO t1 () VALUES ();

# returns '' , 0 , but expected result set is 'x' , 1

SELECT a, LENGTH(a) FROM t1;     

DROP TABLE t1;

13.0.1-opt>CREATE TABLE t1 (a VARCHAR DEFAULT 'x');

Query OK, 0 rows affected (0.012 sec)

13.0.1-opt>SHOW CREATE TABLE t1\G

*************************** 1. row ***************************

       Table: t1

Create Table: CREATE TABLE `t1` (

  `a` text DEFAULT ''

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci

1 row in set (0.000 sec)

13.0.1-opt>INSERT INTO t1 () VALUES ();

Query OK, 1 row affected (0.002 sec)

13.0.1-opt>SELECT a, LENGTH(a) FROM t1;

+------+-----------+

| a    | LENGTH(a) |

+------+-----------+

|      |         0 |

+------+-----------+

1 row in set (0.000 sec)

13.0.1-opt>DROP TABLE t1;

Query OK, 0 rows affected (0.007 sec)

13.0.1-opt>