Re: Strict aliasing and pointers to functions

[malc <av1474 at comtv dot ru>]

On Sun, 26 Nov 2006, Andrew Haley wrote:


[..snip..]

> Are we talking ISO C or GNU C here?  This is OK for GNU C, and I think
> for POSIX.

You mentioned ISO C a few times. So i'd guess we are talking c89.

> > However i'm not targetting standard C
>
> So why are you using -pedantic?  -pedantic is only for strict ISO C.

Because i happen to compile with 5-6 versions of gcc on different 
platforms with different ideas of what -W[xxx] turns on and throwing
`-pedantic' into the mix generally turns on more.

[..snip..]

> ...
> * The cast below is the correct way to handle the problem.
> * The (void *) cast is to avoid a GCC warning like:
> * "warning: dereferencing type-punned pointer will break \
> * strict-aliasing rules"
> * which is wrong this code. (void *) introduces a compatible
> * intermediate type in the cast list.
> */
> count -= got, *(char **)(void *)&buffer += size * got;
>
> I'm not convinced this hackery is correct by my reading of ISO C, and
> in any case it's pointless.  It could be replaced by:
>
> count -= got, buffer = (char*)buffer + (size * got);

That's not for me to decide, not a language layer by any stretch of
imagination.

--
vale