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

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

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)