Re: [PATCH v2] misra: add deviation of Rule 17.7

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

On 2025-08-26 09:45, Jan Beulich wrote:
> On 26.08.2025 09:36, Dmytro Prokopchuk1 wrote:
>> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
>> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
>> @@ -575,6 +575,11 @@ safe."
>>  -config=MC3A2.R17.7,calls+={safe, "any()", 
>> "decl(name(__builtin_memcpy||__builtin_memmove||__builtin_memset||cpumask_check))"}
>>  -doc_end
>> 
>> +-doc_begin="It is safe to deviate functions like 'memcpy()', 
>> 'memset()', 'memmove()', as they return a value purely for 
>> convenience,
>> +their primary functionality (memory manipulation) remains unaffected, 
>> and their return values are generally non-critical and seldom relied 
>> upon."
>> +-config=MC3A2.R17.7,calls+={safe, "any()", 
>> "decl(name(memcpy||memset||memmove))"}
>> +-doc_end
>> +
>>  #
>>  # Series 18.
>>  #
>> --- a/docs/misra/deviations.rst
>> +++ b/docs/misra/deviations.rst
>> @@ -576,6 +576,13 @@ Deviations related to MISRA C:2012 Rules:
>>           - __builtin_memset()
>>           - cpumask_check()
>> 
>> +   * - R17.7
>> +     - It is safe to deviate functions like 'memcpy()', 'memset()', 
>> 'memmove()',
>> +       as they return a value purely for convenience, their primary 
>> functionality
>> +       (memory manipulation) remains unaffected, and their return 
>> values are
>> +       generally non-critical and seldom relied upon.
>> +     - Tagged as `safe` for ECLAIR.
> 
> I realize I may be overly nitpicky here, but in files named 
> deviations.* I find it
> odd to read "It is safe to deviate ...". I further find the use of 
> "like" odd when
> you enumerate the complete set anyway.
> 
> I wonder whether the deviation wants generalizing anyway: Informational 
> return
> values are generally okay to ignore. That is, the Eclair configuration 
> would be
> limited to the three functions for now, but the text / comment could 
> already be
> broader. Then, for example, open-coded uses of the corresponding 
> builtin functions
> would also be covered right away.
> 

While I understand the pragmatic reasoning, from a MISRA compliance 
standpoint it would be better not to make the written justification and 
the actual deviation diverge, and then wide both the ECLAIR 
configuration and its justification suitably once new cases want to be 
deviated. Other than that,

Reviewed-by: Nicola Vetrini <nicola.vetrini@bugseng.com>

-- 
Nicola Vetrini, B.Sc.
Software Engineer
BUGSENG (https://bugseng.com)
LinkedIn: https://www.linkedin.com/in/nicola-vetrini-a42471253