On 2016.10.12 at 12:26 +0200, Jakub Jelinek wrote: > On Wed, Oct 12, 2016 at 11:52:02AM +0200, Bernd Schmidt wrote: > > On 10/12/2016 11:31 AM, Markus Trippelsdorf wrote: > > >On 2016.10.12 at 00:34 +0200, Bernd Schmidt wrote: > > >>It's a discussion we should have, but I agree it should be done > > >>incrementally. I would argue for =1 as the default. > > > > > >Here are some numbers for an allmodconfig Linux kernel on pcc64le: > > > > > >-Wimplicit-fallthrough=1 : 951 warnings > > >-Wimplicit-fallthrough=2 : 1087 warnings > > >-Wimplicit-fallthrough=3 : 1209 warnings > > > > > >I randomly looked at the differences and almost all additional > > >-Wimplicit-fallthrough=2 warnings are bogus (~5% are genuine). > > >And _all_ additional -Wimplicit-fallthrough=3 warnings appear > > >to be bogus. > > > > And that's for a codebase that was written in English to begin with. Would > > you mind posting one or two examples if you saw interesting ones, for > > reference? > > > > This result suggests that we should probably collapse levels 3-5 into a > > single strict one that doesn't try to be clever, and definitely make at most > > level 1 the default. > > What do you mean at most? level 0 is the warning disabled, that is the > default except for -Wextra. The difference between =1 and =2 is very small > amount of warnings, one will need to annotate or add break; to those 951 > spots anyway to make it -Wextra clean (those that don't have any kind of > comment at all), so just handling the additional 136 ones as well is not > that big deal. It would be interesting to see those 136 comments though, > whether anything in them is about the intentional fall through or if they > are just unrelated.
Here are some examples: /* Don't break */ /* drop through */ //very popular /* fall though */ /* pass through... */ /* break intentionally omitted */ /* fallthough */ /* Don't break, this is a failed frame! */ /* leave break out intentionly */ /* else: Fall trough */ /* passthrough */ /* NOBREAK */ /* follow thru */ /* go through here */ -- Markus
