Date: Thu, 22 Aug 2002 22:31:01 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Garrett Wollman <wollman@lcs.mit.edu> Cc: archie@dellroad.org, <arch@FreeBSD.ORG> Subject: Re: NULL Message-ID: <20020822221905.H3508-100000@gamplex.bde.org> In-Reply-To: <200208220245.g7M2jD8A004461@khavrinen.lcs.mit.edu>
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On Wed, 21 Aug 2002, Garrett Wollman wrote:
> In article <200208212358.g7LNw8l08243@arch20m.dellroad.org> you write:
> >Seems like the same is true of "0".. e.g., suppose that pointers
> >are larger than integers, and you call a variadic function with
> >"NULL" as one of the extra parameters:
> >
> > printf("foo=%p num=%d\n", NULL, 123);
> >
> >This would get screwed with NULL=0 but work right with NULL=(void *)0.
>
> That's a feature. (Unfortunately, this feature is not implemented on
> ILP32 architectures. Is 0LL allowed as a null pointer constant? That
> would break everyone equally in this case.)
I think it is not implemented on many I32LP64 arches either, since most
arches with 64-bit pointers have pass all args as 64-bit. Everything
between ((signed char)0) and ((uintmax_t)0) is allowed. uintmax_t
would have to be > 64 bits to break the 64-bit arches equally.
Bruce
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