Re: [XEN PATCH] automation/eclair: add deviations for MISRA C:2012 Rule 16.3

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 15 Dec 2023, Federico Serafini wrote:
> MISRA C:2012 Rule 16.3 states that an unconditional break statement
> shall terminate every switch-clause.
> 
> Update ECLAIR configuration to take into account:
>   - continue, goto, return statements;
>   - functions that do not give the control back;
>   - fallthrough pseudo-keyword;
>   - macro BUG();
>   - comments.
> 
> Update docs/misra/deviations.rst accordingly.
> 
> Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>

This is much sharper and better than before, thanks Federico!


> ---
>  .../eclair_analysis/ECLAIR/deviations.ecl     | 28 +++++++++++++++++++
>  docs/misra/deviations.rst                     | 28 +++++++++++++++++++
>  2 files changed, 56 insertions(+)
> 
> diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
> b/automation/eclair_analysis/ECLAIR/deviations.ecl
> index 683f2bbfe8..e27d840fe4 100644
> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -327,6 +327,34 @@ therefore have the same behavior of a boolean"
>  -config=MC3R1.R14.4,etypes+={deliberate, 
> "stmt(child(cond,child(expr,ref(^<?domain>?::is_dying$))))","src_type(enum)"}
>  -doc_end
>  
> +#
> +# Series 16.
> +#
> +
> +-doc_begin="Switch clauses ending with continue, goto, return statements are
> +safe."
> +-config=MC3R1.R16.3,terminals+={safe, 
> "node(continue_stmt||goto_stmt||return_stmt)"}
> +-doc_end
> +
> +-doc_begin="Switch clauses ending with a call to a function that does not 
> give
> +the control back are safe."
> +-config=MC3R1.R16.3,terminals+={safe, "call(property(noreturn))"}
> +-doc_end
> +
> +-doc_begin="Switch clauses ending with pseudo-keyword \"fallthrough\" are
> +safe."
> +-config=MC3R1.R16.3,reports+={safe, 
> "any_area(end_loc(any_exp(text(/fallthrough;/))))"}
> +-doc_end
> +
> +-doc_begin="Switch clauses ending with failure method \"BUG()\" are safe."
> +-config=MC3R1.R16.3,reports+={safe, 
> "any_area(end_loc(any_exp(text(/BUG\\(\\);/))))"}
> +-doc_end
> +
> +-doc_begin="Switch clauses not ending with the break statement are safe if an
> +explicit comment indicating the fallthrough intention is present."
> +-config=MC3R1.R16.3,reports+={safe, 
> "any_area(end_loc(any_exp(text(^(?s).*/\\* [fF]all ?through.? 
> \\*/.*$,0..1))))"}
> +-doc_end
> +
>  #
>  # Series 20.
>  #
> diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
> index eda3c8100c..d593be81b9 100644
> --- a/docs/misra/deviations.rst
> +++ b/docs/misra/deviations.rst
> @@ -276,6 +276,34 @@ Deviations related to MISRA C:2012 Rules:
>         therefore have the same behavior of a boolean.
>       - Project-wide deviation; tagged as `deliberate` for ECLAIR.
>  
> +   * - R16.3
> +     - Switch clauses ending with continue, goto, return statements are safe.
> +     - Tagged as `safe` for ECLAIR.
> +
> +   * - R16.3
> +     - Switch clauses ending with a call to a function that does not give
> +       the control back are safe.

NIT: it might be good to add:

  (noreturn)

to the statement for clarity but it is good enough already


> +     - Tagged as `safe` for ECLAIR.
> +
> +   * - R16.3
> +     - Switch clauses ending with failure method \"BUG()\" are safe.
> +     - Tagged as `safe` for ECLAIR.
> +
> +   * - R16.3
> +     - Existing switch clauses not ending with the break statement are safe 
> if
> +       an explicit comment indicating the fallthrough intention is present.
> +       However, the use of such comments in new code is deprecated:
> +       pseudo-keyword "fallthrough" shall be used.

          ^NIT: the pseudo-keyword

both changes could be done on commit

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> +     - Tagged as `safe` for ECLAIR. The accepted comments are:
> +         - /\* fall through \*/
> +         - /\* fall through. \*/
> +         - /\* fallthrough \*/
> +         - /\* fallthrough. \*/
> +         - /\* Fall through \*/
> +         - /\* Fall through. \*/
> +         - /\* Fallthrough \*/
> +         - /\* Fallthrough. \*/
> +
>     * - R20.7
>       - Code violating Rule 20.7 is safe when macro parameters are used:
>         (1) as function arguments;
> -- 
> 2.34.1
>