Syntax error thrown when SELECT executed inside a stored procedure, where a local variable is referenced in the WHERE clause.

select `m8`.`t1`.`a` AS `a`,`m8`.`t2`.`a` AS `a` from `m8`.`t1` join `m8`.`t2` where `m8`.`t1`.`a` > x@0;

MariaDB [m8]> select `m8`.`t1`.`a` AS `a`,`m8`.`t2`.`a` AS `a` from `m8`.`t1` join `m8`.`t2` where `m8`.`t1`.`a` > x@0;

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 '@0' at line 1

create database m8;use m8;

create user u3@localhost; grant all on *.* to u3@localhost;

create table t1( a int);

create table t1(a int)  ENGINE="FEDERATED" CONNECTION='mysql://u3@127.0.0.1:3306/m8/t1';

set global federated_pushdown=ON;

DELIMITER |

CREATE PROCEDURE p(x int) BEGIN

select * from t1,t2 WHERE t1.a>x;  

END|

DELIMITER ;

CALL p(0);