Re: change "microcode: Use fallthrough attribute on clang 10 and 11 too." broke the build for me

[Chris Hanson]

On 2/14/21 4:44 PM, Taylor R Campbell wrote:

> > Date: Sun, 14 Feb 2021 16:10:35 -0800
> > From: Chris Hanson <cph@chris-hanson.org>
> > References: <20210214221024.50A4F60858@jupiter.mumble.net>
> >
> > OK, we have to treat the Apple clang differently.
> That seems reasonable -- I suggested
>
> #define FALLTHROUGH() [[fallthrough]]
>
> under #ifdef __APPLE__ but I don't have a way to test and I forget
> whether that patch worked for Arthur.
That might work on Apple's clang 12, but it doesn't work on earlier 
versions. In any case, that's a syntax from C23, which seems a bit 
optimistic.
> > Prior to v12 no attribute is necessary as there are no warnings for
> > falling through. Starting with v12 the usual attribute is required and
> > works.
> That may be accurate on macOS, but it does not seem to be accurate in
> general -- this is the report with clang 10 that motivated me to the
> reduce __clang_major__ >= 12 test to __clang_major__ >= 10:
>
> https://lists.gnu.org/archive/html/mit-scheme-devel/2021-02/msg00004.html
> > I'll make the change and cherry-pick to release-11, unless you want to
> > do it.
> Go for it!

Done.

I notice that there are several other microcode changes that seem 
related to the new macs. Should those be cherry-picked too? If you agree 
could you please select the relevant ones?

I'd like to release 11.2 with working support for the new macs.