Messages in this thread | | | Subject | Re: [RFC][PATCH 0/9] -Wshadow: Making the kernel build clean with -Wshadow | From | Valdis.Kletnieks@vt ... | Date | Mon, 10 Jul 2006 09:23:48 -0400 |
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On Mon, 10 Jul 2006 14:53:19 +0200, Arjan van de Ven said:
> I'm just about always in favor of having automated tools help us find > bugs. However... can you give an indication of how many real bugs you > have encountered? If it's "mostly noise" all the time.. then it's maybe > not worth the effort... while if you find real bugs then it's obviously > worthwhile to go through this.
I started doing similar a while back, and I hadn't come across any actual bugs either. However, there's 2 aspects to this:
1) The cleanup cases that Jesper is doing (which are pretty similar to what I was doing) are mostly "function prototypes in .h files use a variable name that collides with another global variable" ('up' for example). (My nominee for patch 10/9:
include/net/tcp.h:469: warning: declaration of '__x' shadows a previous local include/net/tcp.h:469: warning: shadowed declaration is here
2) The actual *bugs* are most probably in the "variable in .c file shadows a global".
As Jesper notes, it's hard to see the latter when there's 38,000+ noise warnings....
To get a good estimate of the *actual* bug rate, grep for how many *.c files trigger the warning when built with -Wshadow - there's 695 of *those* in my current config.
When I did a bunch of cleanups a while ago to make -Wundef work, I think I scared up exactly one actual bug - but it was a subtle one in the NFS code that wouldn't have been easu to find otherwise...
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