Support for default values for PL/SQL procedure / function

Oracle PL/SQL supports default values for parameters to procedures and functions, which is not supported by SQL/PL in MariaDB. This is a commonly used PL/SQL feature and looks like this, this works fine with Oracle but doesn't compile with MariaDB (excluding SQL_MODE and delimiter, obviously):

SET SQL_MODE=Oracle;

delimiter //

CREATE OR REPLACE PROCEDURE p1(a1 INTEGER := 1)

IS

   dummy INTEGER;

BEGIN

   SELECT a1 INTO dummy FROM dual;

END;

//

CREATE OR REPLACE FUNCTION f1(a1 INTEGER := 1)

RETURN INTEGER

IS

BEGIN

   RETURN a1;

END;

//