Re: [PATCH 2/3] misra: add deviation of Rule 5.5

[Jan Beulich <jbeulich@xxxxxxxx>]

On 23.04.2025 01:43, victorm.lira@xxxxxxx wrote:
> From: Federico Serafini <federico.serafini@xxxxxxxxxxx>
> 
> MISRA C Rule 5.5 states that:
> "Identifiers shall be distinct from macro names".
> 
> A common pattern in Xen is to have a function-like macro that acts as a
> "wrapper" for the function to be called:
> before calling the function, the macro adds additional checks or
> increase/decrease the number of parameters depending on the
> configuration.
> 
> Update ECLAIR configuration and deviations.rst.
> 
> Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
> Signed-off-by: Victor Lira <victorm.lira@xxxxxxx>
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> Cc: Michal Orzel <michal.orzel@xxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Julien Grall <julien@xxxxxxx>
> Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> Cc: Federico Serafini <federico.serafini@xxxxxxxxxxx>
> Cc: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> ---
>  automation/eclair_analysis/ECLAIR/deviations.ecl | 8 ++++++++
>  docs/misra/deviations.rst                        | 8 ++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
> b/automation/eclair_analysis/ECLAIR/deviations.ecl
> index ffa23b53b7..303b06203a 100644
> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -114,6 +114,14 @@ it defines would (in the common case) be already 
> defined. Peer reviewed by the c
>  -config=MC3A2.R5.5,reports+={deliberate, 
> "any_area(decl(kind(function))||any_loc(macro(name(memcpy||memset||memmove))))&&any_area(any_loc(file(^xen/common/libelf/libelf-private\\.h$)))"}
>  -doc_end
> 
> +-doc_begin="Clashes between function-like macros and function names are
> +deliberate since a common pattern in Xen is to have a function-like macro
> +that acts as a \"wrapper\" for the function to be called:
> +before calling the function, the macro adds additional checks or
> +increase/decrease the number of parameters depending on the configuration."
> +-config=MC3A2.R5.5,reports+={deliberate, 
> "all_area(macro(function_like())||decl(kind(function)))"}
> +-doc_end
> +
>  -doc_begin="The type \"ret_t\" is deliberately defined multiple times,
>  depending on the guest."
>  
> -config=MC3A2.R5.6,reports+={deliberate,"any_area(any_loc(text(^.*ret_t.*$)))"}
> diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
> index d116aca7b9..a93ef1ff44 100644
> --- a/docs/misra/deviations.rst
> +++ b/docs/misra/deviations.rst
> @@ -130,6 +130,14 @@ Deviations related to MISRA C:2012 Rules:
>         memmove.
>       - Tagged as `deliberate` for ECLAIR.
> 
> +   * - R5.5
> +     - Clashes between function-like macros and function names are
> +       deliberate

They may or may not be deliberate, depending on context. I don't think it's a
good move to deviate this more widely than necessary. If I get the expression
above (in deviations.ecl) right, even

void func1(int);
void func2(int);

#define func1() func2(0)
#define func2() func1(0)

would be deviated, which I don't think we want. Especially when, in a less
contrived scenario, the clash may not easily be visible.

Jan

> since a common pattern in Xen is to have a function-like
> +       macro that acts as a "wrapper" for the function to be called:
> +       before calling the function, the macro adds additional checks or
> +       increase/decrease the number of parameters depending on the 
> configuration.
> +     - Tagged as `deliberate` for ECLAIR.
> +
>     * - R5.6
>       - The type ret_t is deliberately defined multiple times depending on the
>         type of guest to service.
> --
> 2.47.0