Re: Optimizing writes to unchanged files during merges?

[Linus Torvalds <torvalds@linux-foundation.org>]

On Sun, Apr 15, 2018 at 6:44 PM, Junio C Hamano <gitster@pobox.com> wrote:
>
> I think Elijah's corrected was_tracked() also does not care "has
> this been renamed".

I'm perfectly happy with the slightly smarter patches. My patch was
really just an RFC and because I had tried it out.

> One thing that makes me curious is what happens (and what we want to
> happen) when such a "we already have the changes the side branch
> tries to bring in" path has local (i.e. not yet in the index)
> changes.  For a dirty file that trivially merges (e.g. a path we
> modified since our histories forked, while the other side didn't do
> anything, has local changes in the working tree), we try hard to
> make the merge succeed while keeping the local changes, and we
> should be able to do the same in this case, too.

I think it might be nice, but probably not really worth it.

I find the "you can merge even if some files are dirty" to be really
convenient, because I often keep stupid test patches in my tree that I
may not even intend to commit, and I then use the same tree for
merging.

For example, I sometimes end up editing the Makefile for the release
version early, but I won't *commit* that until I actually cut the
release. But if I pull some branch that has also changed the Makefile,
it's not worth any complexity to try to be nice about the dirty state.

If it's a file that actually *has* been changed in the branch I'm
merging, and I'm more than happy to just stage the patch (or throw it
away - I think it's about 50:50 for me).

So I don't think it's a big deal, and I'd rather have the merge fail
very early with "that file has seen changes in the branch you are
merging" than add any real complexity to the merge logic.

                Linus