[Cocci] Fwd: Re: sizeof (struct tYpO *) : it is just a typo or rather a bug ?

[julia.lawall@lip6.fr (Julia Lawall)]

On Mon, 28 Jul 2014, Toralf F?rster wrote:

> On 07/28/2014 10:13 PM, Julia Lawall wrote:
> > Thanks for the forward.  It should be possible to do something with 
> > Coccinelle.
> > 
> > How did you use grep, though?
> > 
> > julia
> > 
> 1:
> 	grep -Hr "sizeof[ *(]struct .* \*.)"  | cut -f2- -d':' | tee ~/tmp/out
> 
> 2:
> 	cat ~/tmp/out | perl -wane 'chomp(); my ($left, $right) = split (/sizeof\(/); print $right, "\n";' | cut -f2 -d' ' | sort -u | cut -f1 -d')' | grep -v '^+' | while read i; do echo $i; git grep -q "struct $i {" || echo error; echo; done
> 
> 3:
> 	ignore false positives

OK :)

julia

> 
> 
> > On Mon, 28 Jul 2014, Toralf F?rster wrote:
> > 
> >> Hi Dear cocci,
> >>
> >> may I forward to you this email from the LKML, Henrique thinks, that that issue worth a coccinelle patch
> >> :-D
> >>
> >>
> >> -------- Original Message --------
> >> Subject: Re: sizeof (struct tYpO *) : it is just a typo or rather a bug ?
> >> Date: Fri, 25 Jul 2014 08:20:39 -0300
> >> From: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
> >> To: Toralf F?rster <toralf.foerster@gmx.de>
> >> CC: linux-ia64 at vger.kernel.org, ceph-devel at vger.kernel.org, Linux Kernel <linux-kernel@vger.kernel.org>
> >>
> >> On Thu, 24 Jul 2014, Toralf F?rster wrote:
> >>> Inspired by this "typo" fix 
> >>> http://article.gmane.org/gmane.linux.kernel/1754640
> >>> I grep'ed the current git tree of linus for similar issues.
> >>
> >> I wonder if we couldn't use Coccinelle to do that?  I would say it would be
> >> not as cool as deep grep magick, but Coccinelle is cool by definition and
> >> therefore immune from any such comparisons :-)
> >>
> >>> Nevertheless I was told, that gcc doesn't complain about such things due
> >>> to eventually evaluating it to "sizeof(null)". I'm however curious if at
> >>> least a warning should be emitted in such a case, or?
> >>
> >> Well, it cannot become a real bug because the moment the code changes to
> >> actually access/derreference such a typo, it will cause the compiler to
> >> abort with an error.  If gcc will have to waste a measurable amount of time
> >> to issue such a warning, it is not worth it.
> >>
> >> OTOH, such typos could confuse someone reading the code into thinking
> >> they're dealing with a different structure or something, and it _is_
> >> incorrect code no matter how harmless, so it makes sense to fix all such
> >> typos eventually.
> >>
> >> -- 
> >>   "One disk to rule them all, One disk to find them. One disk to bring
> >>   them all and in the darkness grind them. In the Land of Redmond
> >>   where the shadows lie." -- The Silicon Valley Tarot
> >>   Henrique Holschuh
> >>
> >>
> >>
> >> _______________________________________________
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> >> Cocci at systeme.lip6.fr
> >> https://systeme.lip6.fr/mailman/listinfo/cocci
> 
> 
> -- 
> Toralf
> 
>