From: Emily Shaffer <emilyshaffer@google.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org
Subject: Re: [PATCH] clone: teach --single-branch and --branch during --recurse
Date: Thu, 16 Jan 2020 14:38:00 -0800 [thread overview]
Message-ID: <20200116223800.GM181522@google.com> (raw)
In-Reply-To: <20200109081150.GC3978837@coredump.intra.peff.net>
On Thu, Jan 09, 2020 at 03:11:50AM -0500, Jeff King wrote:
> On Wed, Jan 08, 2020 at 03:19:00PM -0800, Emily Shaffer wrote:
>
> > Subject: clone: teach --single-branch and --branch during --recurse
>
> A minor nit, but this subject confused me for a moment. I think we'd
> usually say "teach" for a new feature being implemented, and this is
> really just about passing along the existing features. Something like:
>
> clone: pass --single-branch and --branch when recursing submodules
>
> would have been a bit more obvious (to me anyway).
>
> > Previously, performing "git clone --recurse-submodules --single-branch"
> > resulted in submodules cloning all branches even though the superproject
> > cloned only one branch. Pipe --single-branch and its friend, --branch,
> > through the submodule helper framework to make it to 'clone' later on.
>
> Since I don't really use submodules, I don't have much data or even
> intuition to go on. But could this be a regression for some situations?
> E.g., imagine I have a repo "parent" whose branch "foo" has a submodule
> "child", but "child" only has a branch "bar". What happens now if I "git
> clone --recurse-submodules --single-branch -b foo parent", and what will
> happen after this patch?
>
> I think it works before, but doesn't now.
>
> Setting up like this:
>
> git init child
> (
> cd child
> git checkout -b bar
> echo whatever >file
> git add file
> git commit -m 'child commit'
> )
>
> git init parent
> cd parent
> git checkout -b foo
> git submodule add $PWD/../child
> git commit -m 'add submodule'
>
> if I use the current tip of master, I get:
>
> $ git clone --recurse-submodules --single-branch -b foo parent cur
> Cloning into 'cur'...
> done.
> Submodule 'child' (/home/peff/tmp/parent/../child) registered for path 'child'
> Cloning into '/home/peff/tmp/cur/child'...
> done.
> Submodule path 'child': checked out 'b5cbfcc9fec3b7d67e305468624fed2ba1aa4758'
>
> $ git -C cur/child log -1 --oneline | cat
> b5cbfcc child commit
>
> with your patch, I get:
>
> $ git.compile clone --recurse-submodules --single-branch -b foo parent new
> Cloning into 'new'...
> done.
> Submodule 'child' (/home/peff/tmp/parent/../child) registered for path 'child'
> Cloning into '/home/peff/tmp/new/child'...
> warning: Could not find remote branch foo to clone.
> fatal: Remote branch foo not found in upstream origin
> fatal: clone of '/home/peff/tmp/parent/../child' into submodule path '/home/peff/tmp/new/child' failed
> Failed to clone 'child'. Retry scheduled
> Cloning into '/home/peff/tmp/new/child'...
> warning: Could not find remote branch foo to clone.
> fatal: Remote branch foo not found in upstream origin
> fatal: clone of '/home/peff/tmp/parent/../child' into submodule path '/home/peff/tmp/new/child' failed
> Failed to clone 'child' a second time, aborting
>
> $ git -C new/child log -1 --oneline | cat
> 11acb3a add submodule
>
> (there's nothing checked out in the submodule).
>
> I have no idea how common this kind of thing would be, and I expect in
> most cases your patch would do what people want. But we might need to be
> better about retrying without those options when the first clone fails.
Yeah, that's interesting. A retry sounds like a pretty solid approach,
although if someone's being cautious and using --single-branch I wonder
if that's really something they want (since that's avoiding grabbing
extraneous branches).
I suppose at the very least, --single-branch without --branch should
become recursive. Whether --branch should become recursive, I'm not
totally sure.
The two scenarios I see in conflict are this:
- Superproject branch "foo"
- submodule A branch "foo"
- submodule B branch "foo"
and
- Superproject branch "foo"
- submodule A branch "bar"
- submodule B branch "baz"
If we propagate --branch, the first scenario Just Works, and the second
scenario requires something like:
git clone --recurse-submodules=no --single-branch --branch foo https://superproject
git submodule update --init --single-branch --branch bar A/
git submodule update --init --single-branch --branch baz B/
(I guess if the superproject knows what branch it wants for all the submodules,
you could also just do "git submodule update --init --single-branch" and
have it go and ask for all of them.)
If we don't propagate --branch, the second scenario Just Works, and the
first scenario requires something like:
git clone --recurse-submodules=no --single-branch --branch foo https://superproject
git submodule update --init --single-branch --branch foo
(That is, I think as long as 'update' takes --branch, even if it's not
passed along by 'clone', it should still work OK when delegating to
everyone.)
Let me know if I misunderstood what you were worried about.
I don't use submodules heavily for myself either. I'll try and ask
around a little to see what folks want, at least here. The ergonomics
seem pretty similar, so I guess it comes down to having explicit
documentation.
>
> -Peff
next prev parent reply other threads:[~2020-01-16 22:38 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-08 23:19 [PATCH] clone: teach --single-branch and --branch during --recurse Emily Shaffer
2020-01-08 23:39 ` Emily Shaffer
2020-01-09 8:11 ` Jeff King
2020-01-16 22:38 ` Emily Shaffer [this message]
2020-01-17 21:03 ` Jeff King
2020-01-27 22:20 ` Emily Shaffer
2020-01-27 22:49 ` Emily Shaffer
2020-01-27 23:10 ` Jeff King
2020-01-28 1:08 ` Emily Shaffer
2020-01-28 1:31 ` Jeff King
2020-01-28 2:10 ` Emily Shaffer
2020-01-27 23:00 ` Jeff King
2020-01-28 22:17 ` [PATCH v2] clone: pass --single-branch during --recurse-submodules Emily Shaffer
2020-01-30 10:23 ` Jeff King
2020-02-21 2:53 ` Emily Shaffer
2020-02-21 3:16 ` Jeff King
2020-02-21 3:10 ` [PATCH v3 0/2] propagate --single-branch during clone --recurse-submodules Emily Shaffer
2020-02-21 3:10 ` [PATCH v3 1/2] submodule--helper: use C99 named initializer Emily Shaffer
2020-02-21 5:26 ` Jeff King
2020-02-22 20:13 ` Junio C Hamano
2020-02-21 3:10 ` [PATCH v3 2/2] clone: pass --single-branch during --recurse-submodules Emily Shaffer
2020-02-21 5:28 ` Jeff King
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