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Re: Change default level for -Wimplicit-fallthrough
On 2016.11.03 at 13:32 +0100, Jakub Jelinek wrote:
> On Thu, Nov 03, 2016 at 01:22:11PM +0100, Bernd Schmidt wrote:
> > On 11/03/2016 12:58 PM, Jakub Jelinek wrote:
> > >On Thu, Nov 03, 2016 at 12:51:15PM +0100, Bernd Schmidt wrote:
> > >>I'm concerned about the number of false positives for this warning, and
> > >>judging by previous discussions, I'm not alone in this. This patch limits it
> > >>to level 1 (any comment before the case label disables the warning) for
> > >>cases where the user specified no explicit level. It'll still generate
> > >>enough noise that people will be aware of it and can choose whether to use a
> > >>higher level or not.
> > >>
> > >>Bootstrapped and tested on x86_64-linux. Ok?
> > >
> > >I disagree, I'm ok with changing it to 2, but 1 is too much.
> >
> > Well, we have data from our own sources where we had to "fix" lots of
> > perfectly good code, and also from the Linux kernel. From an earlier
> > discussion:
>
> That data wasn't really convincing on this. All it proved is that most of
> the cases are (likely) deliberate fall-throughs without any comment
> whatsoever, the rest is in the noise. As one needs to deal with those
> where comments are missing altogether, dealing with the noise is acceptable.
Without Bernd's patch to set the default to 1 you will drown in false
positives once you start using gcc-7 to build a whole distro. On my
Gentoo test box anything but level 1 is simply unacceptable, because you
will miss important other warnings in the -Wimplicit-fallthrough noise
otherwise.
--
Markus