[gentoo-portage-dev] Re: [RFC PATCH gentoolkit] bin: Add merge-driver-ekeyword

[Matt Turner <mattst88@gentoo.org>]

On Wed, Dec 23, 2020 at 2:46 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Matt Turner <mattst88@gentoo.org> writes:
>
> > I want to handle conflicts automatically on lines like
> >
> >> KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86"
> >
> > where conflicts frequently happen by adding/removing ~ before the
> > architecture names or adding/removing whole architectures. I don't
> > know if I should use a custom git merge driver or a custom git merge
> > strategy.
>
> A merge strategy is about how the changes at the tree level are
> handled.  A merge driver is given three blobs (original, your
> version, and their version) and comes up with a merged blob.
>
> In your case, you'd want a custom merge driver if you want to handle
> word changes on a single line, because the default text merge driver
> is pretty much line oriented.

Thanks, that makes sense. The merge driver I've written seems to work
great for handling the KEYWORDS=... line.

If users could more simply opt into using it (e.g., on the command
line rather than enabling it via ~/.gitattributes) I think it would be
fine to use. Better yet, is there a way git can be configured to
fallback to another merge driver if the first returns a non-zero
status due to unresolved conflicts? For example, if there are changes
to other lines, how can I fall back to another merge driver?

Thank you for your advice!