Re: Wanted: shallow submodule clones with --no-single-branch.

From: Stefan Beller <sbeller@google.com>
Date: Jan 3, 2017, 19:21 UTC
Message-ID: <CAGZ79kYZwSM78FoytDm9VhFY0D=Z1tzoq=tW7h65kSCYSr0grQ@mail.gmail.com>
In-Reply-To: <CAAmwXB=M8yZY2sFLwavrrQSEW9bipFhNZyLduwYXtZNK6-Ppxg@mail.gmail.com>

On Fri, Dec 30, 2016 at 2:50 AM, Tor Andersson <tor@ccxvii.net> wrote:

Show 5 quoted lines

> Hi,
>
> When adding submodules with --depth=1 only the master branch is
> cloned. This often leaves the submodule pointing to a non-existing
> commit.

You can also use the "--branch=not_master" flag to track another branch. This however doesn't clone the correct branch. I would have expected that it cloned the correct branch instead.

>
> It would be useful if I could pass the --no-single-branch argument to
> the submodule clone process, since then a submodule can point to any
> tag or branch without ending up in this situation.

Adding --no-single-branch sounds like a good idea for general use, but it seems like a clunky workaround when looking for a specific branch, i.e. fixing the --branch flag sounds like the right approach for this issue here?

> I've got a local
> patch to hardwire the --no-single-branch argument in the
> builtin/submodule--helper.c clone_submodule function, but I'm not sure
> if this will have any other adverse effects?

Well, when asking for depth=1, the user usually actually wants to have the least amount of data, which is why --depth implies --single-branch in clone.

So adding it unconditionally is a bad idea IMHO, we'd need to have a flag for that propagated from git-submodule.sh (function cmd_add) to the submodule--helpers module_clone.

>
> Better yet would be for the shallow submodule clone to automatically
> retrieve and graft the actual commit the submodule points to, but
> that's probably wishing for too much.

I think fixing the branch option comes a bit closer, but still doesn't fix this root problem. "submodule update" tries to fetch by sha1 directly in the hope that the server has uploadpack.\ allowReachableSHA1InWant configured.

In "submodule add" I think it is sufficient to take the current remotes $branch and record that, so I do not see the need in the add code to support direct sha1s unlike the update command?

Thanks, Stefan