lkml.org 
[lkml]   [2006]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Don't compare unsigned variable for <0 in sys_prctl()
On 29/11/06, Linus Torvalds <torvalds@osdl.org> wrote:
>
>
> On Wed, 29 Nov 2006, Jesper Juhl wrote:
> >
> > I would venture that "-Wshadow" is another one of those.
>
> I'd agree, except for the fact that gcc does a horribly _bad_ job of
> -Wshadow, making it (again) totally unusable.
>
> For example, it's often entirely interesting to hear about local variables
> that shadow each other. No question about it.
>
> HOWEVER. It's _not_ really interesting to hear about a local variable that
> happens to have a common name that is also shared by a extern function.
>
> There just isn't any room for confusion, and it's actually not even that
> unusual - I tried using -Wshadow on real programs, and it was just
> horribly irritating.
>
> In the kernel, we had obvious things like local use of "jiffies" that just
> make _total_ sense in a small inline function, and the fact that there
> happens to be an extern declaration for "jiffies" just isn't very
> interesting.
>
> Similarly, with nested macro expansion, even the "local variable shadows
> another local variable" case - that looks like it should have an obvious
> warning on the face of it - really isn't always necessarily that
> interesting after all. Maybe it is a bug, maybe it isn't, but it's no
> longer _obviously_ bogus any more.
>
> So I'm not convinced about the usefulness of "-Wshadow". ESPECIALLY the
> way that gcc implements it, it's almost totally useless in real life.
>
> For example, I tried it on "git" one time, and this is a perfect example
> of why "-Wshadow" is totally broken:
>
> diff-delta.c: In function 'create_delta_index':
> diff-delta.c:142: warning: declaration of 'index' shadows a global declaration
>
> (and there's a _lot_ of those). If I'm not allowed to use "index" as a
> local variable and include <string.h> at the same time, something is
> simply SERIOUSLY WRONG with the warning.
>
> So the fact is, the C language has scoping rules for a reason. Can you
> screw yourself by usign them badly? Sure. But that does NOT mean that the
> same name in different scopes is a bad thing that should be warned about.
>
> If I wanted a language that didn't allow me to do anything wrong, I'd be
> using Pascal. As it is, it turns out that things that "look" wrong on a
> local level are often not wrong after all.
>

I can't really say anything else at this point but, point conceded...

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please http://www.expita.com/nomime.html
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-11-29 02:13    [W:0.046 / U:3.828 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site