Re: EVENT_INIT and obs. kbd_buffer_gcpro: 'arg' init still needed?

[Adrian Robert <arobert@cogsci.ucsd.edu>]

On Jun 1, 2006, at 5:56 AM, YAMAMOTO Mitsuharu wrote:

>>>>>> On Wed, 31 May 2006 09:50:35 -0400, Adrian Robert  
>>>>>> <arobert@cogsci.ucsd.edu> said:
>
>> One use of the termhooks.h EVENT_INIT() macro in macterm.c also takes
>> care to init the event's 'arg' to "Qnil", explaining with this  
>> comment:
>
>>        /* It is necessary to set this (additional) argument slot  
>> of an
>> 	 event to nil because keyboard.c protects incompletely
>> 	 processed event from being garbage collected by placing them
>> 	 in the kbd_buffer_gcpro vector.  */
>
>> However, according to the ChangeLog this vector was removed on
>> 2004-01-21 in response to changes on 2003-06-15, including the very
>> introduction of the EVENT_INIT() macro.
>
> I removed this comment that is referring to a nonexistent variable
> from macterm.c.
>
>> My question is, is the additional call to set 'arg' to "Qnil", found
>> in w32, mac, and x terms, still needed?  I notice that macterm does
>> not have it for other calls to EVENT_INIT.  Other terms only use
>> EVENT_INIT once.
>
> Although bzero'ed Lisp_Object corresponds to integer 0 and thus it
> does not leads to a real problem, I think we should not rely on this.
> So I added some code to set `arg' to Qnil in macterm.c.

So a non-nil 'arg' CAN lead to errors?
Then is there any reason not to do the Qnil init in the EVENT_INIT  
macro?  All places using it have lisp.h.