Re: [XEN PATCH] automation/eclair: add deviations for MISRA C:2012 Rule 16.4

[Jan Beulich <jbeulich@xxxxxxxx>]

On 23.04.2024 12:02, Federico Serafini wrote:
> --- a/docs/misra/deviations.rst
> +++ b/docs/misra/deviations.rst
> @@ -302,6 +302,19 @@ Deviations related to MISRA C:2012 Rules:
>         leave such files as is.
>       - Tagged as `deliberate` for ECLAIR.
>  
> +   * - R16.4
> +     - Switch statements having a controlling expression of enum type
> +       deliberately do not have a default case: gcc -Wall enables -Wswitch
> +       which warns (and breaks the build as we use -Werror) if one of the 
> enum
> +       labels is missing from the switch.
> +     - Tagged as `deliberate` for ECLAIR.
> +
> +   * - R16.4
> +     - A switch statement with a single switch clause and no default label 
> may
> +       be used in place of an equivalent if statement if it is considered to
> +       improve readability."

First a terminology related comment here: I'm afraid "switch clause" can be
interpreted multiple ways, when I think we want to leave no room for
interpretation here. It's not even clear to me whether

    switch ( x )
    {
    case 1: case 2: case 3: case 4:
        ...
        break;
    }

would be covered by the deviation, or whether the multiple case labels
wouldn't already be too much.

And then it is not clear to me why

    switch ( x )
    {
    case 1:
        ...
        break;
    default:
        ...
        break;
    }

shouldn't also be covered, as potentially a readability improvement /
future change simplification over

    if ( x == 1 )
    {
        ...
    }
    else
    {
        ...
    }

Jan