On Wed, Jun 20, 2012 at 10:20 AM, Joao Paulo Rechi Vita <jprvita@xxxxxxxxxxxxx> wrote: > On Tue, Jun 19, 2012 at 6:41 PM, Lucas De Marchi > <lucas.demarchi@xxxxxxxxxxxxxx> wrote: >> On Tue, Jun 19, 2012 at 3:29 PM, Joao Paulo Rechi Vita >> <jprvita@xxxxxxxxxxxxx> wrote: >>> On Fri, Jun 15, 2012 at 9:45 AM, Henrique Dante <hdante@xxxxxxxxxxxxxx> wrote: >>>> On Fri, Jun 15, 2012 at 9:43 AM, Henrique Dante <hdante@xxxxxxxxxxxxxx> wrote: >>>>> On Fri, Jun 15, 2012 at 9:29 AM, Anderson Lizardo >>>>> <anderson.lizardo@xxxxxxxxxxxxx> wrote: >>>>>> Hi Henrique, >>>>>> >>>>>> On Fri, Jun 15, 2012 at 8:04 AM, Henrique Dante de Almeida >>>>>> <hdante@xxxxxxxxxxxxxx> wrote: >>>>>>> --- >>>>>>> gdbus/object.c | 39 +++++++++++++++++++++------------------ >>>>>>> gdbus/watch.c | 4 ++-- >>>>>>> 2 files changed, 23 insertions(+), 20 deletions(-) >>>>>> >>>>>> Would it be interesting to add this option to acinclude.m4? Or does it >>>>>> generate too much noise? >>>>> >>>>> It generates few warnings. Depending on the acceptance of this patch, >>>>> I could fix bluez as a whole and add -Wshadow to acinclude.m4. >>>> >>>> Actually, I had a partial build here. Ignore the previous answer, it >>>> generates a lot of warnings. >>>> >>> >>> If we're not going to enable -Wshadow by default, does it make sense >>> to apply this patch? Who is going to check if no new shadow warnings >>> are being inserted in new commits? >> >> I'm all for doing the following: >> >> 1) Fix all the places with shadow variables >> 2) Add -Wshadow to the warning flags >> >> There are lots of them. >> > > Yes, that makes sense. > Or not completely, as researching a little bit on what kind of warnings -Wshadow generates shows that not all of them are useful [1] (I'm quoting the relevant part of this link below). I think before getting our hands dirty to change this, we should look if we want to live with all the restrictions imposed by it. Opinions? [1] http://kerneltrap.org/node/7434 """ From: Linus Torvalds [email blocked] Subject: Re: [PATCH] Don't compare unsigned variable for <0 in sys_prctl() Date: Tue, 28 Nov 2006 16:13:05 -0800 (PST) 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. Linus """ -- João Paulo Rechi Vita Openbossa Labs - INdT -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
