Re: [XEN PATCH 09/13] xen/common: address violations of MISRA C:2012 Directive 4.10

[Jan Beulich <jbeulich@xxxxxxxx>]

On 31.08.2023 12:08, Simone Ballarin wrote:
> On 29/08/23 08:50, Jan Beulich wrote:
>> On 28.08.2023 15:20, Simone Ballarin wrote:
>>> Add inclusion guards to address violations of
>>> MISRA C:2012 Directive 4.10 ("Precautions shall be taken in order
>>> to prevent the contents of a header file being included more than
>>> once").
>>>
>>> Also C files, if included somewhere, need to comply with the guideline.
>>>
>>> Mechanical change.
>>>
>>> Signed-off-by: Simone Ballarin <simone.ballarin@xxxxxxxxxxx>
>>> ---
>>>   xen/common/compat/grant_table.c | 7 +++++++
>>>   xen/common/coverage/gcc_4_7.c   | 5 +++++
>>>   xen/common/decompress.h         | 5 +++++
>>>   xen/common/event_channel.h      | 5 +++++
>>>   xen/common/multicall.c          | 5 +++++
>>>   5 files changed, 27 insertions(+)
>>
>> As already said in reply to another patch, imo .c files shouldn't gain such
>> guards. These are commonly referred to as "header guards" for a reason.
>>
> 
> This is the MISRA's definition of "header file" (MISRA C:2012 Revision 
> 1, Appendix J):
> 
>    "A header file is any file that is the subject of a #include
>     directive.
>     Note: the filename extension is not significant."

That's completely misleading terminology then.

> So, the guards are required if we want to comply with the directive, 
> otherwise we can raise a deviation.
> 
> The danger of multi-inclusion also exists for .c files, why do you want 
> to avoid guards for them?

Counter question: Why only add guards to some of them? (My personal
answer is "Because it's extra clutter.")

Jan