threads / discuss / 54414

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

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

## tl;dr

5 messages between Oct 14, 2020 and Oct 15, 2020.

replies: 4people: 2as markdown or json

Marc Sune· Oct 14, 2020, 10:14 UTC · lore
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

Philippe Blain· Oct 14, 2020, 13:29 UTC · re: Marc Sune · lore

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

Hi Marc,
Show 30 quoted lines
> 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
Cheers,
Philippe.
Marc Sune· Oct 14, 2020, 14:35 UTC · re: Philippe Blain · lore

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

Philippe,

Missatge de Philippe Blain <levraiphilippeblain@gmail.com> del dia dc., 14 d’oct. 2020 a les 15:29:

Show 39 quoted lines
>
> 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

Show 5 quoted lines
>
> Cheers,
>
> Philippe.
>
Philippe Blain· Oct 14, 2020, 22:51 UTC · re: Marc Sune · lore

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

Hi Marc,
Show 56 quoted lines
> Le 14 oct. 2020 à 10:35, Marc Sune <marcdevel@gmail.com> a écrit :
> 
> 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).
Did you try `git submodule foreach` ? If you are scripting, you could do:
    git diff --stat && git submodule foreach [--recursive] git diff --stat
Although here the recursion is an all-or-nothing business.
Show 9 quoted lines
> 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.

I think 'log' is useful; it's more descriptive then having just a hash, which is the default...

Show 21 quoted lines
> 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.

I'm not sure of the use case for these... The history of the submodule project can be seen with `git -C path/to/submodule log` (or just `cd` there and `git log`), and the history of the gitlink in the superproject with `git log -- path/to/submodule`...

It does not really make sense to interleave the history of the superproject and the submodule in the same output, in my opinion at least.

> Let me know if any of this resonates, and if some patches along these
> lines would be welcomed
I can't really answer that, I'm just a small time contributor :)
> (might ask some help offlist).
You should ask on the list, on the mentoring list, or on IRC (see [1]).
[1] https://git-scm.com/docs/MyFirstContribution#getting-help

Cheers, Philippe.

Marc Sune· Oct 14, 2020, 22:59 UTC · re: Philippe Blain · lore

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

Philippe,

Missatge de Philippe Blain <levraiphilippeblain@gmail.com> del dia dj., 15 d’oct. 2020 a les 0:51:

Show 63 quoted lines
>
> Hi Marc,
>
> > Le 14 oct. 2020 à 10:35, Marc Sune <marcdevel@gmail.com> a écrit :
> >
> > 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).
>
> Did you try `git submodule foreach` ? If you are scripting, you could do:
>
>     git diff --stat && git submodule foreach [--recursive] git diff --stat

Yes, ofc. There are multiple reasons for not using it in this specific case I am facing (specially performance), but this is probably offtopic.

Show 50 quoted lines
>
> Although here the recursion is an all-or-nothing business.
>
> > 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.
>
> I think 'log' is useful; it's more descriptive then having just a hash,
> which is the default...
>
> > 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.
>
> I'm not sure of the use case for these... The history
> of the submodule project can be seen with `git -C path/to/submodule log`
> (or just `cd` there and `git log`), and the history of the gitlink in the superproject
> with `git log -- path/to/submodule`...
>
> It does not really make sense to interleave the history of the superproject and
> the submodule in the same output, in my opinion at least.
>
> > Let me know if any of this resonates, and if some patches along these
> > lines would be welcomed
>
> I can't really answer that, I'm just a small time contributor :)

I will wait for some thoughts on the proposal, and to see if someone can shed some light on the reasons why `--submodule=` option works the way it does, today, in git diff.

Regards marc

Show 10 quoted lines
>
> > (might ask some help offlist).
>
> You should ask on the list, on the mentoring list, or on IRC (see [1]).
>
> [1] https://git-scm.com/docs/MyFirstContribution#getting-help
>
> Cheers,
> Philippe.
>

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