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

[Simone Ballarin <simone.ballarin@xxxxxxxxxxx>]

On 31/08/23 13:10, Jan Beulich wrote:
> 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.
I might agree with you on this, but either way this is the definition to 
apply when reading the guideline. IMHO here, the best would be to use a 
separate extension for "C files intended to be included" (but that's not 
the point).
> > 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
It's not "some of them", it's exactly the ones used in an #include 
directive, so I'm not getting your objection.
By the way, if the community agrees, I can deviate all C files and
drop the changes.

--
Simone Ballarin, M.Sc.

Field Application Engineer, BUGSENG (https://bugseng.com)