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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 15 Nov 2023, Jan Beulich wrote:
> 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@xxxxxxx>
> 
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> 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".

Done on commit