Re: [PATCH v4 00/10] Sparse index: delete ignored files outside sparse cone

> >   8:  febef675f05 !  9:  c19d93ec5d7 sparse-checkout: clear tracked sparse dirs
> >      @@ Commit message
> >           the sparse directory. This depends on the indexed version of the file,
> >           so the sparse directory must be expanded.
> >
> >      +    We must take special care to look for untracked, non-ignored files in
> >      +    these directories before deleting them. We do not want to delete any
> >      +    meaningful work that the users were doing in those directories and
> >      +    perhaps forgot to add and commit before switching sparse-checkout
> >      +    definitions. Since those untracked files might be code files that
> >      +    generated ignored build output, also do not delete any ignored files
> >      +    from these directories in that case. The users can recover their state
> >      +    by resetting their sparse-checkout definition to include that directory
> >      +    and continue. Alternatively, they can see the warning that is presented
> >      +    and delete the directory themselves to regain the performance they
> >      +    expect.

> >      +
> >           By deleting the sparse directories when changing scope (or running 'git
> >           sparse-checkout reapply') we regain these performance benefits as if the
> >           repository was in a clean state.
> >      @@ Documentation/git-sparse-checkout.txt: case-insensitive check. This corrects for
> >        'git sparse-checkout set' command to reflect the expected cone in the working
> >        directory.
> >
> >      -+The cone mode sparse-checkout patterns will also remove ignored files that
> >      -+are not within the sparse-checkout definition. This is important behavior
> >      -+to preserve the performance of the sparse index, but also matches that
> >      -+cone mode patterns care about directories, not files. If there exist files
> >      -+that are untracked and not ignored, then Git will not delete files within
> >      -+that directory other than the tracked files that are now out of scope.
> >      -+These files should be removed manually to ensure Git can behave optimally.
> >      ++When changing the sparse-checkout patterns in cone mode, Git will inspect each
> >      ++tracked directory that is not within the sparse-checkout cone to see if it
> >      ++contains any untracked files. If all of those files are ignored due to the
> >      ++`.gitignore` patterns, then the directory will be deleted. If any of the
> >      ++untracked files within that directory is not ignored, then no deletions will
> >      ++occur within that directory and a warning message will appear. If these files
> >      ++are important, then reset your sparse-checkout definition so they are included,
> >      ++use `git add` and `git commit` to store them, then remove any remaining files
> >      ++manually to ensure Git can behave optimally.