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

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

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