Re: [PATCH] Makefile: Convert -Wimplicit-fallthrough=3 to just -Wimplicit-fallthrough for clang

From: Nathan Chancellor <natechancellor@gmail.com>
To: Joe Perches <joe@perches.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	LKML <linux-kernel@vger.kernel.org>,
	clang-built-linux@googlegroups.com
Subject: Re: [PATCH] Makefile: Convert -Wimplicit-fallthrough=3 to just -Wimplicit-fallthrough for clang
Date: Sat, 10 Aug 2019 19:04:42 -0700	[thread overview]
Message-ID: <20190811020442.GA22736@archlinux-threadripper> (raw)
In-Reply-To: <6a5f470c1375289908c37632572c4aa60d6486fa.camel@perches.com>

On Sat, Aug 10, 2019 at 01:18:22PM -0700, Joe Perches wrote:
> On Sat, 2019-08-10 at 12:44 -0700, Linus Torvalds wrote:
> > On Sat, Aug 10, 2019 at 12:32 PM Joe Perches <joe@perches.com> wrote:
> > > What does it take for this sort of patch to be applied by you?
> > 
> > The basic rule tends to be: "normal channels".
> []
> > I pulled from Gustavo earlier today to add a few more expected switch
> > fall-through's, I guess I can take this Makefile change directly.
> 
> Thanks. It's simple enough.
> 
> There are classes of patches generated by scripts that have
> no real mechanism to be applied today.
> 
> For instance: global coccinelle scripted changes to use stracpy
> https://lore.kernel.org/lkml/alpine.DEB.2.21.1907251747560.2494@hadrien/
> 
> and trivial scripted changes to MAINTAINERS
> https://lore.kernel.org/lkml/6482e6546dc328ec47b07dba9a78a9573ebb3e56.camel@perches.com/
> 
> that are basically impossible to be applied by anyone but you.
> 
> Otherwise there are hundreds of little micro patches most of
> which would not otherwise be applied.
> 
> There should be some process available to get these treewide
> or difficult to keep up-to-date and apply patches handled.
> 
> I believe these sorts of scripted patches should ideally
> be handled immediately before an RC1 so other trees can be 
> synchronized in the simplest way possible.
> 

Hi Joe,

On a tangential note, how are you planning on doing the fallthrough
comment to attribute conversion? The reason I ask is clang does not
support the comment annotations, meaning that when Nathan Huckleberry's
patch is applied to clang (which has been accepted [1]), we are going
to get slammed by the warnings. I just ran an x86 defconfig build at
296d05cb0d3c with his patch applied and I see 27673 instances of this
warning... (mostly coming from some header files so nothing crazy but it
will be super noisy).

If you have something to share like a script or patch, I'd be happy to
test it locally.

[1]: https://reviews.llvm.org/D64838

Cheers,
Nathan