Re: [PATCH v2] misra: add R21.1 R21.2

[Jan Beulich <jbeulich@suse.com>]

On 14.11.2023 23:59, Stefano Stabellini wrote:
> Add 21.1 and 21.2, with a longer comment to explain how strategy with
> leading underscores and why we think we are safe today.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
with one nit:

> --- a/docs/misra/rules.rst
> +++ b/docs/misra/rules.rst
> @@ -519,6 +519,28 @@ maintainers if you want to suggest a change.
>         they are related
>       -
>  
> +   * - `Rule 21.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_01.c>`_
> +     - Required
> +     - #define and #undef shall not be used on a reserved identifier or
> +       reserved macro name
> +     - Identifiers starting with an underscore followed by another underscore
> +       or an upper-case letter are reserved. Today Xen uses many, such as
> +       header guards and bitwise manipulation functions. Upon analysis it turns
> +       out Xen identifiers do not clash with the identifiers used by modern
> +       GCC, but that is not a guarantee that there won't be a naming clash in
> +       the future or with another compiler.  For these reasons we discourage
> +       the introduction of new reserved identifiers in Xen, and we see it as
> +       positive the reduction of reserved identifiers. At the same time,
> +       certain identifiers starting with an underscore are also commonly used
> +       in Linux (e.g. __set_bit) and we don't think it would be an improvement
> +       to rename them.

I think this last sentence would also better say "two underscores".

Jan