Re: [PATCH v5 4/7] submodule: add extension to encode gitdir paths

> On Mon, Dec 08, 2025 at 11:01:33AM +0200, Adrian Ratiu wrote:
>> On Sun, 07 Dec 2025, Junio C Hamano <gitster@pobox.com> wrote:
>> > Patrick Steinhardt <ps@pks.im> writes:
>> >
>> >> Maybe the right approach would be to tell users to never manually enable
>> >> the extension and instead to provide a command that both:
>> >>
>> >>   - Persists the submodule gitdirs for any populated submodules in the
>> >>     gitconfig.
>> >>
>> >>   - Enables the repsitory extension.
>> >>
>> >> If we had that then we could count on the submodule gitdirs to exist in
>> >> the gitconfig, and if they don't we would die with an error message that
>> >> indicates that the repository is broken, maybe even with a hint for the
>> >> user on how to fix it.
>> >
>> > I personally like the simplicity of this approach.
>> >
>> > I haven't however thought about operational complexity, if one has
>> > an existing user base that have been using a custom pathname munging
>> > code that needs to be migrated to the new scheme.
>> 
>> The good news is that for all the real-world use cases I'm aware of,
>> migration to the new scheme should just work.
>> 
>> The problem we're discussing here (automatic fallback vs requiring the
>> gitdir to always exist + using a migration tool) does add a bit of
>> operational complexity, however it might be manageable.
>> 
>> I have to see how this works in practice, especially with the users
>> setting the config (likely I'll add an error to block that path) and the
>> build-config to enable the extension by default (will likely run the
>> migration tool automatically on existing repositories if enabled via the
>> build-config).
>> 
>> I will attempt this approach in v6.
>
> One suggestion: it might be sensible to move auto-migration into a
> subsequent patch series. That way we can focus on the general approach
> of the new extension at first, and the potentially-bigger discussion
> around whether or not to auto-migrate users can then be had separately.