Memory leak on re-compilation of a failing statement inside a stored routine

Consider the following use case:

CREATE TABLE t1 (a INT);

CREATE PROCEDURE p1()

SELECT * FROM t1;

CALL p1();

DROP TABLE t1;

CREATE TABLE t1 (a INT);

CALL p1(); # <<=== Second call of the stored procedure p1 could lead to memory leaks

Memory leaks is caused by re-parsing of the failed statement (SELECT * FROM t1 in the mentioned case). On re-parsing, a memory is allocated on sp_head memory root that was already marked as read-only after first success execution of the stored procedure p1.

This issue is fixed by adding a new memory root to SP-instruction on starting re-parsing process and forwarding further memory allocations that will taken place on re-parsing of a SP instruction's statement to this new memory root. Please draw attention, that a memory for the new mem_root is allocated on sp_head's memory root and pointer to the new memory root is stored inside the SP-instruction class sp_lex_instr.