Re: [XEN PATCH][for-4.19 v2 1/1] xen: introduce a deviation for Rule 11.9

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 17/10/2023 08:51, Jan Beulich wrote:
> On 16.10.2023 18:49, Nicola Vetrini wrote:
> > On 16/10/2023 15:43, Jan Beulich wrote:
> > > On 11.10.2023 14:46, Nicola Vetrini wrote:
> > > > --- a/xen/include/xen/compiler.h
> > > > +++ b/xen/include/xen/compiler.h
> > > > @@ -109,13 +109,16 @@
> > > >
> > > >  #define offsetof(a,b) __builtin_offsetof(a,b)
> > > >
> > > > +/* Access the field of structure type, without defining a local
> > > > variable */
> > > > +#define access_field(type, member) (((type *)NULL)->member)
> > > This is not a field access, so I consider the macro misnamed. 
> > > Question
> > > is
> > > whether such a helper macro is needed in the first place.
> > >
> > > > +#define typeof_field(type, member) typeof(access_field(type, 
> > > > member))
> > > If this needs adding, it wants to come ...
> > >
> > > >  /**
> > > >   * sizeof_field(TYPE, MEMBER)
> > > >   *
> > > >   * @TYPE: The structure containing the field of interest
> > > >   * @MEMBER: The field to return the size of
> > > >   */
> > > > -#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
> > > > +#define sizeof_field(TYPE, MEMBER) sizeof(access_field(TYPE, 
> > > > MEMBER))
> > > ... with a commend similar as this one has. (Or the commend could be
> > > slightly altered to cover both).
> > I added access_field since it's possibly useful on its own in the
> > future,
> > but that may not be the case. Not a real field access, perhaps a
> > fake_access_field?
> I don't like this either, I'm afraid: This isn't a fake access. Maybe
> field_of() or field_of_type()? Yet at this point I'd still prefer for
> this to not be a separate macro in the first place.
>
> Jan
Ok, no problem.

--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)