[lkml]   [2020]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 000/141] Fix fall-through warnings for Clang
On Fri, Nov 20, 2020 at 10:53:44AM -0800, Jakub Kicinski wrote:
> On Fri, 20 Nov 2020 12:21:39 -0600 Gustavo A. R. Silva wrote:
> > This series aims to fix almost all remaining fall-through warnings in
> > order to enable -Wimplicit-fallthrough for Clang.
> >
> > In preparation to enable -Wimplicit-fallthrough for Clang, explicitly
> > add multiple break/goto/return/fallthrough statements instead of just
> > letting the code fall through to the next case.
> >
> > Notice that in order to enable -Wimplicit-fallthrough for Clang, this
> > change[1] is meant to be reverted at some point. So, this patch helps
> > to move in that direction.
> >
> > Something important to mention is that there is currently a discrepancy
> > between GCC and Clang when dealing with switch fall-through to empty case
> > statements or to cases that only contain a break/continue/return
> > statement[2][3][4].
> Are we sure we want to make this change? Was it discussed before?
> Are there any bugs Clangs puritanical definition of fallthrough helped
> find?
> IMVHO compiler warnings are supposed to warn about issues that could
> be bugs. Falling through to default: break; can hardly be a bug?!

It's certainly a place where the intent is not always clear. I think
this makes all the cases unambiguous, and doesn't impact the machine
code, since the compiler will happily optimize away any behavioral

Kees Cook

 \ /
  Last update: 2020-11-20 20:33    [W:2.888 / U:0.828 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site