last_insert_id() should return ulonglong, but is longlong

[Dvir Azulay]

Hello, this is my first time on this mailing list so I hope I'm on the
right place.

Last night I encountered an issue with LAST_INSERT_ID(), when my ID
column is an UNSIGNED BIGINT; the return value was a SIGNED BIGINT.

So I looked at the source code and saw this line:
 longlong Item_func_last_insert_id::val_int()

When in other places, it was referred to as ulonglong, here it is
longlong. (When it should be ulonglong of course).

Is this correct or am I looking at the wrong place?