MySQL Bugs: #3671: Stored procedure crash if function has "set @variable=param"

Bug #3671	Stored procedure crash if function has "set @variable=param"
Submitted:	6 May 2004 2:27	Modified:	13 Mar 2005 7:32
Reporter:	Peter Gulutzan	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server	Severity:	S3 (Non-critical)
Version:	5.0.1-alpha-debug	OS:	Linux (SuSE 8.2)
Assigned to:	Dmitry Lenev	CPU Architecture:	Any

Description:
If a function contains "SET @system_variable = parameter", and for the parameter I pass a 
column value, then using the function in a SELECT causes a crash. 

How to repeat:
mysql> delimiter // 
mysql> create function f (p int) returns int begin set @a = 5; return 5; end;// 
Query OK, 0 rows affected (0.01 sec) 
 
mysql> create table t190 (s1 int)// 
Query OK, 0 rows affected (0.08 sec) 
 
mysql> insert into t190 values (4),(7),(5)// 
Query OK, 3 rows affected (0.00 sec) 
Records: 3  Duplicates: 0  Warnings: 0 
 
mysql> select f(s1) from t190// 
ERROR 2013 (HY000): Lost connection to MySQL server during query

I do not get the disconnect with 5.0.1-alpha (current as I write this), but the results are incorrect (6 rows: '', '5', '', '5', '', '5').

Another way to crash, still using "SET @variable ..." but with no parameter, is this: 
 
mysql> create table t7 (s1 int,s2 int)// 
Query OK, 0 rows affected (0.56 sec) 
 
mysql> insert into t7 values (1,2)// 
Query OK, 1 row affected (0.01 sec) 
 
mysql> create function f7 () returns int begin set @a = @a; return @a; end;// 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> set @a = 1;// 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> select * from t7 where s1 = f7() and s2 = f7()+1// 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> select f7()// 
ERROR 2006 (HY000): MySQL server has gone away 
No connection. Trying to reconnect... 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket 
'/tmp/mysql.sock' (111) 
ERROR: 
Can't connect to the server 
 
... 
 
Incidentally, I suppose this is less important than the crash, but: 
the "select * from t7 where s1 = f7() and s2 = f7()+1//" statement 
should have returned one row. And  if you fix that, then 
I intend to change the set statement to "set @a = @a + 1" so that 
the function is non-deterministic.

Hi, Peter!

I can not repeat these crashes with current snapshot of 5.0. All your queries work and return expected results (Except may be your example with non-deterministic function, but it is hard to say which is the correct result for it... Probably it should be reported as separate issue if the result is wrong).
Also since the time you have reported this bug I have done some fixes to the code which was the first suspect for causing these crashes.

So I am closing this bug as fixed in 5.0.3.