Re: [PATCH 1/2] docs/misra: introduce rules.rst

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.05.2022 03:02, Stefano Stabellini wrote:
> On Wed, 25 May 2022, Julien Grall wrote:
>> On 25/05/2022 01:35, Stefano Stabellini wrote:
>>> +- Rule: Dir 4.7
>>> +  - Severity:  Required
>>> +  - Summary:  If a function returns error information then that error
>>> information shall be tested
>>> +  - Link:
>>> https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_07.c
>>
>>
>> ... this one. We are using (void) + a comment when the return is ignored on
>> purpose. This is technically not-compliant with MISRA but the best we can do
>> in some situation.
>>
>> With your proposed wording, we would technically have to remove them (or not
>> introduce new one). So I think we need to document that we are allowing
>> deviations so long they are commented.
> 
> Absolutely yes. All of these rules can have deviations as long as they
> make sense and they are commented. Note that we still have to work out
> a good tagging system so that ECLAIR and cppcheck can recognize the
> deviations automatically but for now saying that they need to be
> commented is sufficient I think.
> 
> So I'll add the following on top of the file:
> 
> """
> It is possible that in specific circumstances it is best not to follow a
> rule because it is not possible or because the alternative leads to
> better code quality. Those cases are called "deviations". They are
> permissible as long as they are documented with an in-code comment.
> """

Hmm, so you really mean in-code comments. I don't think this will scale
well (see e.g. the DCE related intended deviation), and it also goes
against the "no special casing for every static analysis tool" concern
I did voice on the call.

Jan