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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

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.


> No functional change.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> ---
>  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
>