Procedure call not modifying data is affected by strict SQL mode

create procedure pr(a int) select a;

set sql_mode='';

call pr('foo');

set sql_mode='STRICT_ALL_TABLES';

call pr('foo');

drop procedure pr;

MariaDB [test]> set sql_mode='';

Query OK, 0 rows affected (0.000 sec)

MariaDB [test]> call pr('foo');

+------+

| a    |

+------+

|    0 |

+------+

1 row in set (0.000 sec)

Query OK, 0 rows affected, 1 warning (0.000 sec)

MariaDB [test]> set sql_mode='STRICT_ALL_TABLES';

Query OK, 0 rows affected (0.000 sec)

MariaDB [test]> call pr('foo');

ERROR 1366 (22007): Incorrect integer value: 'foo' for column ``.``.`a` at row 1