On Tue, Nov 24, 2020 at 11:24 PM Finn Thain <[email protected]> wrote:
>
> These statements are not "missing" unless you presume that code written
> before the latest de facto language spec was written should somehow be
> held to that spec.
There is no "language spec" the kernel adheres to. Even if it did,
kernel code is not frozen. If an improvement is found, it should be
applied.
> If the 'fallthrough' statement is not part of the latest draft spec then
> we should ask why not before we embrace it. Being that the kernel still
> prefers -std=gnu89 you might want to consider what has prevented
> -std=gnu99 or -std=gnu2x etc.
The C standard has nothing to do with this. We use compiler extensions
of several kinds, for many years. Even discounting those extensions,
the kernel is not even conforming to C due to e.g. strict aliasing. I
am not sure what you are trying to argue here.
But, since you insist: yes, the `fallthrough` attribute is in the
current C2x draft.
Cheers,
Miguel
On Wed, 25 Nov 2020, Miguel Ojeda wrote:
>
> The C standard has nothing to do with this. We use compiler extensions
> of several kinds, for many years. Even discounting those extensions, the
> kernel is not even conforming to C due to e.g. strict aliasing. I am not
> sure what you are trying to argue here.
>
I'm saying that supporting the official language spec makes more sense
than attempting to support a multitude of divergent interpretations of the
spec (i.e. gcc, clang, coverity etc.)
I'm also saying that the reason why we use -std=gnu89 is that existing
code was written in that language, not in ad hoc languages comprised of
collections of extensions that change with every release.
> But, since you insist: yes, the `fallthrough` attribute is in the
> current C2x draft.
>
Thank you for checking. I found a free version that's only 6 weeks old:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2583.pdf
It will be interesting to see whether 6.7.11.5 changes once the various
implementations reach agreement.