Re: [PATCH 2/2] xdiff: implement empty line chunk heuristic

[Jeff King <peff@peff.net>]

On Wed, Apr 20, 2016 at 12:18:27AM -0400, Jeff King wrote:

> My earlier tests with the perl script were all done with "git log -p",
> which will not show anything at all for merges (and my script wouldn't
> know how to deal with combined diffs anyway). But I think this new patch
> _will_ kick in for combined diffs (because it is built on individual
> diffs). It will be interesting to see if this has any effect there, and
> what it looks like.
> 
> We should be able to see it (on a small enough repository) with:
> 
>   git log --format='commit %H' --cc --merges
> 
> and comparing the before/after.

Add in "-p" if you are testing the tip of jk/diff-compact-heuristic. It
is based on the older maintenance track in which "--cc" does not imply
"-p".

Looking over the results, it's about what you'd expect (comment blocks
shifted by one as we want, and then there happens to be a one-line
conflict resolved later in the hunk).

The most interesting thing I found was db65f0fc3b1e. There we have two
functions being added in the same spot, and the resolution obviously is
to put one after the other. So both sides do the usual comment-block
thing, and the resulting combined diff carries through that improvement
as you'd expect.

-Peff