Re: git diff --submodule=diff and --stat/--dirstat/--name-only

[Marc Sune <marcdevel@gmail.com>]

Philippe,

Missatge de Philippe Blain <levraiphilippeblain@gmail.com> del dia
dc., 14 d’oct. 2020 a les 15:29:
>
> Hi Marc,
>
> > Le 14 oct. 2020 à 06:14, Marc Sune <marcdevel@gmail.com> a écrit :
> >
> > Hello all,
> >
> > First, thank you to the community for the great work. Worth saying it
> > from time to time, I think.
> >
> > I am dealing with a couple of big repositories that use git
> > submodules. They have nested submodules, and some of them are pretty
> > huge. I came across:
> >
> > git diff --submodule=diff
> >
> > Which is very handy for creating some tooling, but it's obviously slow
> > - in the order of tens of minutes in my case - for big diffs. I was
> > only interested in the list files that changed, in this particular
> > case, but:
> >
> > git diff --stat --submodule=diff
> >
> > doesn't seem to honour `--submodule=diff` and it doesn't go into the
> > submodule(s) nor recurses, of course. Other options like `--dirstat`
> > or `--name-only` seem to behave the same way.
> >
> > I've tried this v2.20.1 and the HEAD of master (d4a392452e) with the
> > same results. Is this a missing feature, a bug or is it just the
> > intended behaviour?
> >
> > Regards
> > marc
>
> This would indeed be useful. It's a missing feature, and so intended behaviour
> for the moment, I would say. It was discussed recently on the list [1] :
>
>
> [1] https://lore.kernel.org/git/20200924063829.GA1851751@coredump.intra.peff.net/t/#u

Thank you for the pointer and the clarification.

I am not sure extending `git diff` options (only) under
`--submodule=`, e.g. `--submodule=stat` is the way to go. It seems
redundant to me.

I am wondering if it would make sense to have basic options of git
commands, e.g. `git diff --stat`, be honoured for submodules too, and
just control whether git commands should get in the submodule(s) or
not, and perhaps the depth of the recursion (optionally).

For instance, I don't fully get the use-case(s) in which parts of the
output are --stat (supermodule) and submodules show something
different:

git diff --stat --submodule=diff
git diff --stat --submodule=log

Specially for log, this sounds to me like it should be under `git
log`, with the appropriate options. Perhaps you can shed some light on
the use-cases these combinations support.

I would think something like:

git diff --stat --submodule-follow
git diff --stat --submodule-follow-depth=4

git diff --names-only --submodule-follow
git diff --dirstat --submodule-follow

and for other commands (some sort of header line should be printed to
note the history is under the submodule X):

git log --submodule-follow
git log --submodule-follow-depth=4

and of course allowing `--` modifier:

git log --submodule-follow -- libs/library1

would be easier to use.

Let me know if any of this resonates, and if some patches along these
lines would be welcomed (might ask some help offlist).

Regards
marc

>
> Cheers,
>
> Philippe.
>