Re: [PATCH 0/9] MISRA C 2012 8.1 rule fixes

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

+Roberto


Hi Roberto,

A quick question about Rule 8.1.


Michal sent a patch series to fix Xen against Rule 8.1 (here is a link
if you are interested: https://marc.info/?l=xen-devel&m=165570851227125)

Although we all generally agree that the changes are a good thing, there
was a question about the rule itself. Specifically, is the following
actually a violation?

  unsigned x;


Looking through the examples in the MISRA document I can see various
instances of more confusing and obvious violations such as:

  const x;
  extern x;

but no examples of using "unsigned" without "int". Do you know if it is
considered a violation?


Thanks!

Cheers,

Stefano



On Wed, 22 Jun 2022, Jan Beulich wrote:
> >>>>> On 22.06.2022 12:25, Jan Beulich wrote:
> >>>>>> On 20.06.2022 09:02, Michal Orzel wrote:
> >>>>>>> This series fixes all the findings for MISRA C 2012 8.1 rule, 
> >>>>>>> reported by
> >>>>>>> cppcheck 2.7 with misra addon, for Arm (arm32/arm64 - target 
> >>>>>>> allyesconfig).
> >>>>>>> Fixing this rule comes down to replacing implicit 'unsigned' with 
> >>>>>>> explicit
> >>>>>>> 'unsigned int' type as there are no other violations being part of 
> >>>>>>> that rule
> >>>>>>> in the Xen codebase.
> >>>>>>
> >>>>>> I'm puzzled, I have to admit. While I agree with all the examples in 
> >>>>>> the
> >>>>>> doc, I notice that there's no instance of "signed" or "unsigned" there.
> >>>>>> Which matches my understanding that "unsigned" and "signed" on their 
> >>>>>> own
> >>>>>> (just like "long") are proper types, and hence the omission of "int"
> >>>>>> there is not an "omission of an explicit type".

[...]

> >>>> Neither the name of the variable nor the comment clarify that this is 
> >>>> about
> >>>> the specific case of "unsigned". As said there's also the fact that they
> >>>> don't appear to point out the lack of "int" when seeing plain "long" (or
> >>>> "long long"). I fully agree that "extern x;" or "const y;" lack explicit
> >>>> "int".