Re: [XEN PATCH 03/10] automation/eclair_analysis: deviate macro count_args_ for MISRA Rule 20.7

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

On 2024-04-25 02:28, Stefano Stabellini wrote:
> On Tue, 23 Apr 2024, Nicola Vetrini wrote:
>> The count_args_ macro violates Rule 20.7, but it can't be made
>> compliant with Rule 20.7 without breaking its functionality. Since
>> it's very unlikely for this macro to be misused, it is deviated.
> 
> That is OK but can't we use the SAF- framework to do it, given that it
> is just one macro?
> 
> If not, this is also OK.
> 
> 

It would be more fragile, for no substantial gain

>> No functional change.
>> 
>> Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
>> ---
>>  automation/eclair_analysis/ECLAIR/deviations.ecl | 6 ++++++
>>  docs/misra/deviations.rst                        | 6 ++++++
>>  2 files changed, 12 insertions(+)
>> 
>> diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
>> b/automation/eclair_analysis/ECLAIR/deviations.ecl
>> index d21f112a9b94..c17e2f5a0886 100644
>> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
>> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
>> @@ -445,6 +445,12 @@ not to parenthesize their arguments."
>>  -config=MC3R1.R20.7,reports+={safe, 
>> "any_area(any_loc(any_exp(macro(^alternative_(v)?call[0-9]$))))"}
>>  -doc_end
>> 
>> +-doc_begin="The argument 'x' of the count_args_ macro can't be 
>> parenthesized as
>> +the rule would require, without breaking the functionality of the 
>> macro. The uses
>> +of this macro do not lead to developer confusion, and can thus be 
>> deviated."
>> +-config=MC3R1.R20.7,reports+={safe, 
>> "any_area(any_loc(any_exp(macro(^count_args_$))))"}
>> +-doc_end
>> +
>>  -doc_begin="Uses of variadic macros that have one of their arguments 
>> defined as
>>  a macro and used within the body for both ordinary parameter 
>> expansion and as an
>>  operand to the # or ## operators have a behavior that is 
>> well-understood and
>> diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
>> index ed0c1e8ed0bf..e228ae2e715f 100644
>> --- a/docs/misra/deviations.rst
>> +++ b/docs/misra/deviations.rst
>> @@ -371,6 +371,12 @@ Deviations related to MISRA C:2012 Rules:
>>         sanity checks in place.
>>       - Tagged as `safe` for ECLAIR.
>> 
>> +   * - R20.7
>> +     - The macro `count_args_` is not compliant with the rule, but is 
>> not likely
>> +       to incur in the risk of being misused or lead to developer 
>> confusion, and
>> +       refactoring it to add parentheses breaks its functionality.
>> +     - Tagged as `safe` for ECLAIR.
>> +
>>     * - R20.12
>>       - Variadic macros that use token pasting often employ the gcc 
>> extension
>>         `ext_paste_comma`, as detailed in `C-language-toolchain.rst`, 
>> which is
>> --
>> 2.34.1
>> 

-- 
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)