USE '<db>' is allowed inside a stored routine when executed via the dynamic-SQL path

CREATE DATABASE db_one;

DELIMITER $$

CREATE FUNCTION f() RETURNS INT BEGIN EXECUTE IMMEDIATE 'USE db_one'; RETURN 1; END$$

CREATE PROCEDURE p() BEGIN DECLARE v INT DEFAULT f(); END$$

DELIMITER ;

SELECT DATABASE() AS db_before;  

CALL p();

SELECT DATABASE() AS db_after; 

13.1.0-opt>CREATE DATABASE db_one;

Query OK, 1 row affected (0.001 sec)

13.1.0-opt>DELIMITER $$

13.1.0-opt>CREATE FUNCTION f() RETURNS INT BEGIN EXECUTE IMMEDIATE 'USE db_one'; RETURN 1; END$$

Query OK, 0 rows affected (0.003 sec)

13.1.0-opt>CREATE PROCEDURE p() BEGIN DECLARE v INT DEFAULT f(); END$$

Query OK, 0 rows affected (0.004 sec)

13.1.0-opt>DELIMITER ;

13.1.0-opt>SELECT DATABASE() AS db_before;

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

| db_before |

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

| test      |

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

1 row in set (0.000 sec)

13.1.0-opt>CALL p();

Query OK, 0 rows affected (0.001 sec)

13.1.0-opt>SELECT DATABASE() AS db_after;

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

| db_after |

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

| db_one   |

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

1 row in set (0.000 sec)

13.1.0-opt>

Expected Error

-----------------

13.1.0-opt>CREATE FUNCTION f() RETURNS INT BEGIN USE db_one; RETURN 1; END$$

ERROR 1314 (0A000): USE is not allowed in stored procedures

13.1.0-opt>