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Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".

From: Jason Merrill <jason at redhat dot com>
To: Zack Weinberg <zack at codesourcery dot com>
Cc: Fergus Henderson <fjh at cs dot mu dot oz dot au>, Kazu Hirata <kazu at cs dot umass dot edu>, gcc-patches at gcc dot gnu dot org
Date: Thu, 12 Jun 2003 16:25:28 -0400
Subject: Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
References: <20030612.141353.55502198.kazu@cs.umass.edu><20030612184112.GD8506@mars.cs.mu.oz.au><87of133zoz.fsf@egil.codesourcery.com><20030612185541.GE8506@mars.cs.mu.oz.au><wvlel1zcb5t.fsf@prospero.boston.redhat.com><87k7br3vem.fsf@egil.codesourcery.com>

On Thu, 12 Jun 2003 13:14:57 -0700, Zack Weinberg <zack@codesourcery.com> wrote:

> Jason Merrill <jason@redhat.com> writes:
>
>>>> > I think it would be better style to replace NULL_RTX with NULL
>>>> > rather than with 0.
>>>> 
>>>> GCC sources prefer 0 to NULL for a generic null pointer.
>>>
>>> GCC was once written in K&R C, but times change :-)
>>
>> I prefer NULL to 0.  It is both more readable and more reliable in the
>> presence of varargs.
>
> I won't argue readability (though I disagree) but NULL is *NOT* more
> reliable in the presence of varargs; there is no guarantee that NULL
> doesn't expand to "0".  In the presence of varargs one has no choice
> but to write an explicit cast.

A system that defines NULL to 0 where that is a different size from
(void*)0 is broken.  Does such brokenness actually exist?

Jason

Follow-Ups:
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Zack Weinberg
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Kaveh R. Ghazi

References:
- [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Kazu Hirata
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Fergus Henderson
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Zack Weinberg
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Fergus Henderson
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Jason Merrill
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Zack Weinberg

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