Re: Integrating submodules with no side effects

From: Stefan Beller <sbeller@google.com>
Date: Oct 19, 2016, 19:45 UTC
Message-ID: <CAGZ79kZWaShG9iG565bD3aVYFcb53+opbpnJH-v3G6hrQL2tzA@mail.gmail.com>
In-Reply-To: <CAHd499D_fehBHsNdH9PLQj+H_WAJqbbMhDwv_nCT3fZcX60ENA@mail.gmail.com>

On Wed, Oct 19, 2016 at 12:19 PM, Robert Dailey <rcdailey.lists@gmail.com> wrote:

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> On Wed, Oct 19, 2016 at 11:23 AM, Stefan Beller <sbeller@google.com> wrote:
>> You could try this patch series:
>> https://github.com/jlehmann/git-submod-enhancements/tree/git-checkout-recurse-submodules
>> (rebased to a newer version; no functional changes:)
>> https://github.com/stefanbeller/git/tree/submodule-co
>> (I'll rebase that later to origin/master)
>>
>>>
>>> Do you have any info on how I can prevent that error? Ideally I want
>>> the integration to go smoothly and transparently, not just for the
>>> person doing the actual transition (me) but for everyone else that
>>> gets those changes from upstream. They should not even notice that it
>>> happened (i.e. no failed commands, awkward behavior, or manual steps).
>>
>> It depends on how long you want to postpone the transition, but I plan to
>> upstream the series referenced above in the near future,
>> which would enable your situation to Just Work (tm). ;)
>
> At first glance, what you've linked to essentially looks like
> automated `git submodule update` for every `git checkout`. Am I
> misunderstanding?

Essentially yes, except with stricter rules than the actual submodule update IIRC.

>
> If I'm correct, this is not the same as what I'm talking about. The
> problem appears to be more internal: When a submodule is removed, the
> physical files that were there are not removed by Git.

That is also done by that series: submodules ought to be treated as files: If you checkout a new version where a file is deleted, the checkout command will actually remove the file for you (and e.g. solve any directory/file conflicts that may happen in the transition.)

> It leaves them
> there in the working copy as untracked files.

That is the current behavior as checkout tries hard to ignore submodules.

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> The next step Git takes
> (again, just from outside observation) is to add those very same files
> to the working copy, since they were added to a commit. However, at
> this point Git fails because it's trying to create (write) files to
> the working copy when an exact file of that name already exists there.
> Git will not overwrite untracked files, so at this point it fails.
>
> What needs to happen, somehow, is Git sees that the files were
> actually part of a submodule (which was removed) and remove the
> physical files as well, assuming that they were not modified in the
> submodule itself. This will ensure that the next step (creating the
> files) will succeed since the files no longer block it.

Yep.