Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1

From: Ingo Molnar
Date: Thu Jul 28 2016 - 13:04:31 EST

* Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> But that's my point, I believe the false positive rate is pretty low in fact, due
> to three factors:
> - 90% of the warnings get fixed by developers, we never see them upstream
> - I'd say a majority (say 70%) of the remaining warnings are flagging 'complexity
> bugs'
> - only a residual 3% are obnoxious ones.
> But these remaining 3% are the ones we are seeing again and again in various
> compiler output, so we tend to get a subjective impression that this warning
> produces countless false positives.

And note that I am well aware of the real risk this poses: people will ignore real
warnings if there are so many residual false positives.

I think this approach worked pretty well for perf:

> So I *think* the better option would be to do what we are doing in the perf
> tooling: force a build error for these warnings (by default, with an option
> available to make it build). That flushes them out and also makes it sure that
> those questionable sequences of code never get upstream to begin with.

... but might not be appropriate for the kernel which is a 2 orders of magnitude
larger code base.