Re: [Xen-devel] Re: [patch] fix void* arithmetic

[Jeff Garzik <jeff@xxxxxxxxxx>]

Hollis Blanchard wrote:
> On Tue, 2006-08-29 at 22:06 +0100, Ian Campbell wrote:
> > On Tue, 2006-08-29 at 15:24 -0500, Hollis Blanchard wrote:
> > > Hi Ian, I needed the following patch to avoid lots of these warnings:
> > >         elf.c:238: warning: pointer of type `void *' used in arithmetic
> > >
> > > Fix void* arithmetic warnings.
> > > Signed-off-by: Hollis Blanchard <hollisb@xxxxxxxxxx>
> > Looks like PPC is the only arch using -Wpointer-arith, is there a reason
> > for that?
> Is there are reason the other architectures *aren't* using it?
>
> We have some extra warnings enabled because they've helped us in the
> past (such as -Wshadow). Given that we're just playing janitor for
> everyone else's code though, I think we're about to abandon that one.
Pointer arith is quite valid on void pointers, when using gcc and most 
other modern compilers.
Point of fact, any Linux kernel-related code REQUIRES that void* arith 
be valid, and not cause warnings.
As we see from your patch, all a cast to char* does is complicate the 
code, for zero gain.
        Jeff





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