Re: [RFC/PATCH 00/18] Add --index-only option to git merge

[Michael J Gruber <git@drmicha.warpmail.net>]

Elijah Newren venit, vidit, dixit 08.04.2016 08:58:
> This patch series adds an --index-only flag to git merge, the idea
> being to allow a merge to be performed entirely in the index without
> touching (or even needing) a working tree.
> 
> The core fix, to merge-recursive, was actually quite easy.  The
> recursive merge logic already had the ability to ignore the working
> directory and operate entirely on the index -- it needed to do this
> when creating a virtual merge base, i.e. when o->call_depth > 0.  It's
> just that o->call_depth was also used for other purposes, so I just
> needed to introduce a new flag to disambiguate and switch all the
> necessary index-only-related call sites to use it.  It actually seems
> to make the code slightly easier to read too, which is a nice bonus.
> That was all done in patch 12 of this series.
> 
> Adding all the necessary testcases and switching over the other merge
> strategies turned out to be the harder part...and still has a problem,
> as I'll mention below.

I haven't looked at your series thoroughly but immediately had to think
of 'tr/remerge-diff' (on 'pu'), see
http://permalink.gmane.org/gmane.comp.version-control.git/256591

There, Thomas used index-only merge to reproduce an automatic merge as
the base for a useful "remerge-diff".

I've been rebasing (and using) that series on 'next' for a while now
without any problems; some reasons kept it from being merged on next,
see the thread.

So, it would be interesting whether you solve the same problem
differently, or face the same problems ;)

Michael