Valid query causes invalid view definition due to syntax limitation in FOR SYSTEM_TIME

CREATE TABLE t (i INT) WITH SYSTEM VERSIONING;

CREATE VIEW v AS SELECT * FROM t FOR system_time AS OF DATE_SUB(NOW(), INTERVAL 6 SECOND);

MariaDB [test]> SHOW CREATE VIEW v;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '- interval 6 second' at line 1

TYPE=VIEW

query=select `test`.`t`.`i` AS `i` from `test`.`t` FOR SYSTEM_TIME AS OF current_timestamp() - interval 6 second

md5=7d2a1bb74cba5bc91a2c9495baf8895a

updatable=1

algorithm=0

definer_user=root

definer_host=localhost

suid=2

with_check_option=0

timestamp=2018-02-21 17:19:03

create-version=2

source=SELECT * FROM t FOR system_time AS OF DATE_SUB(NOW(), INTERVAL 6 SECOND)

client_cs_name=utf8

connection_cl_name=utf8_general_ci

view_body_utf8=select `test`.`t`.`i` AS `i` from `test`.`t` FOR SYSTEM_TIME AS OF current_timestamp() - interval 6 second

MariaDB [test]> select `test`.`t`.`i` AS `i` from `test`.`t` FOR SYSTEM_TIME AS OF current_timestamp() - interval 6 second;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '- interval 6 second' at line 1

MariaDB [test]> select `test`.`t`.`i` AS `i` from `test`.`t` FOR SYSTEM_TIME AS OF (current_timestamp() - interval 6 second);

Empty set (0.00 sec)