Re: [PATCH v3 0/6] Sparse checkout: fix bug with worktree of bare repo

[Elijah Newren <newren@gmail.com>]

On Wed, Dec 29, 2021 at 11:40 PM Eric Sunshine <sunshine@sunshineco.com> wrote:
>
> On Wed, Dec 29, 2021 at 4:40 AM Elijah Newren <newren@gmail.com> wrote:>
> > On Tue, Dec 28, 2021 at 1:32 PM Derrick Stolee via GitGitGadget
> > <gitgitgadget@gmail.com> wrote:
> > >      ++init-worktree-config::
> > >      ++
> > >      ++Initialize config settings to enable worktree-specific config settings.
> > >      ++This will set `core.repositoryFormatversion=1` and enable
> > >      ++`extensions.worktreeConfig`, which might cause some third-party tools from
> > >      ++being able to operate on your repository. See CONFIGURATION FILE for more
> > >      ++details.
> >
> > So, if users attempt to use `git worktree add` or `git sparse-checkout
> > {init,set}` without first running this, they can break other
> > worktrees.  And if they do run this new command, they potentially
> > break third-party tools or older git versions.
>
> When you say "can break other worktrees", you don't necessarily mean
> that in general but rather in regard to sparse-checkout -- in
> particular, the sparse-checkout config settings and the
> `info/sparse-checkout file` -- correct? (Genuine question; I want to
> make sure that I'm actually understanding the issues under
> discussion.)

Yes, thanks for the clarifications.

...
> > So, I'd like to reiterate my earlier suggestion which would avoid
> > these regressions while also fixing the reported bug:
> >   * If core.bare=true or core.worktree is set, then at `git worktree
> > add` time, automatically run the logic you have here for
> > init-worktree-config.  Having either of those config settings with
> > multiple worktrees is currently broken in all git versions and likely
> > in most all external tools.  As such, being aggressive in the new
> > config settings to allow new versions of git to work seems totally
> > safe to me -- we can't be any more broken than we already were.
> >   * If core.bare=false and core.worktree is not set, then:
> >     * `git sparse-checkout {init,set}` should set
> > extensions.worktreeConfig if not already set, and always set the
> > core.sparse* and index.sparse settings in worktree-specific files.
> >     * `git worktree add`, if extensions.worktreeConfig is already set,
> > will copy both the info/sparse-checkout file and the config.worktree
> > settings (module core.bare and core.worktree, if present) to the new
> > worktree
>
> Thanks for the clearly written enumeration of how you expect this to
> work. This summary pretty well (or entirely) captures the conclusions
> I arrived at, as well, after devoting a chunk of time today thinking
> through the cases. If I'm understanding everything correctly, the
> approach outlined here solves the bare-worktree problem in the least
> invasive and least dangerous way (for older Git versions and foreign
> tools). And we don't even need the `git worktree init-worktree-config`
> subcommand (though we need the underlying functionality).

I'm glad it helps, and that we appear to be moving towards consensus.  :-)