Re: [PATCH][2.6.6-rc3] gcc-3.4.0 fixes

[Denis Vlasenko]

On Thursday 29 April 2004 12:30, Ihar 'Philips' Filipau wrote:
> Mikael Pettersson wrote:
> > This patch fixes three warnings from gcc-3.4.0 in 2.6.6-rc3:
> > - drivers/char/ftape/: use of cast-as-lvalue
> >  		if (get_unaligned((__u32*)ptr)) {
> > -			++(__u32*)ptr;
> > +			ptr += sizeof(__u32);
> >  		} else {
>
>    Can anyone explain what is the problem with this?
>    To me it seems pretty ligitimate code - why it was outlawed in gcc 3.4?

cast is not a lvalue. ++(__u32*)ptr is nonsense, just like ++4.

>    Previous code was agnostic to type of ptr, but you code presume ptr
> being char pointer (to effectively increment by 4 bytes).

This would be agnostic too:

ptr = (void*) ((char*)ptr + sizeof(__u32));
--
vda

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