Re: [XEN PATCH 10/11] xen/sched: add ASSERT_UNREACHABLE() to address MISRA C:2012 Rule 2.1

[Julien Grall <julien@xxxxxxx>]

On 08/08/2023 16:53, Nicola Vetrini wrote:
> > > ... "return" alone already tells the compiler that "break" is
> > > unreachable. You don't need unreachable() for that. As said before,
> > > "break" like this simply want purging (and Misra is wrong to demand
> > > "break" everywhere - it should instead demand no [unannotated]
> > > fall-through, which can also be achieved by return, continue, and
> > > goto).
> > My suggestion was in the context of this series where we add
> > ASSERT_UNREACHABLE() before break. From my understanding, we don't
> > have a lot of leeway here because, from what Nicola wrote, rule 16.3
> > is mandatory.
> >
> > So I think using unreachable is better if we every decide to use break
> > after return.
> >
> > Cheers,
> 16.3 is not Mandatory, just Required.
Ah I misread what you wrote. In that case...

> I was just reluctant to knowingly 
> add one more violation
> while fixing another before submitting the patch. If indeed 16.3 won't 
> likely be adopted by Xen,
> then that break should indeed go away.
>
> However, the main thing that's holding me back from doing a slimmed-down 
> v2 here is that
> evidently there's no consensus even on the ASSERT_UNREACHABLE() patches.
... I agree with the following statement from Jan:

"it should instead demand no [unannotated] fall-through, which can also 
be achieved by return, continue, and goto"
Cheers,

--
Julien Grall