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

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

[Adrian Robert]

Hi,

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.  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.

Thanks.

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

[YAMAMOTO Mitsuharu]

>>>>> 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.

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp

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

[Adrian Robert]

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.