Re: Coding Style Review and Automation

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Feb 11, 2025 at 09:10:38AM +0000, Luca Fancellu wrote:
> Hi Roger,
> 
> >> 
> >> 3) The size of the patch after applying clang-format is huge. Really. 
> >> Something
> >> like 9 MB. Even if everyone agrees that the approach is good and we can 
> >> proceed
> >> with it, it is highly unlikely anyone will be able to review it. 
> >> Considering
> >> that new patches are being added to the upstream during such a review, it 
> >> may
> >> also lead to new code style violations or require a new review of that huge
> >> patch.
> > 
> > I think this approach is difficult.  It would likely introduce a lot
> > of noise when using `git blame` (I know, it's just one extra jump,
> > but...), plus would likely break every patch that we currently have
> > in-flight.
> 
> I think we already discussed this in the past and having some churn was 
> accepted,
> also about breaking existing patches, every change merged has the potential 
> to do
> that, this one is more likely but it’s the game I guess?

Hm, maybe, I don't get rebasing issues very often TBH.  Not sure how
intrusive such patch would be.

> > 
> >> 4) Which clang-format version should we set as the one used by Xen, so it 
> >> is
> >> easy for everyone to use it on their hosts?
> >> 
> >> 5) You name it. I think many people in the community can name their points 
> >> for
> >> and against clang-format.
> > 
> > What are the parts of our coding style that clang-format cannot
> > correctly represent?  Could you make a list of what would need to
> > change in Xen coding style for it to match perfectly what clang-format
> > will check?
> 
> we already went through that route, there is no checker anywhere that matches
> the Xen coding style perfectly, so it’s either we change the coding style or 
> we
> don’t proceed further with any automatic check

I'm probably fine with changing coding style, that's why I'm asking
for a list of what needs to be changed (unless we switch to a
completely different coding style).

> > 
> > Ideally the first step would be to prepare a patch to adjust the
> > coding style so it's in line with what clang-format will do.
> 
> It’s easy to say that, but difficult to implement, if we could accept the 
> clang-format
> rules it would be easier to adopt the configuration itself as coding style, 
> maybe
> enhanced with some comments.

I'm kind of lost, why is it difficult to implement?  What I'm asking
for is a patch to CODING_STYLE that modifies it in a way that we could
use clang-format.  In any case we need to do that if we want to use
clang-format.

One question that seems to have been dropped from my previous email:
would it be feasible to apply the updated style to newly added chunks
of code only, but not to the (unmodified) surrounding context?

Thanks, Roger.