Re: Improving merge of tricky conflicts

[Martin von Zweigbergk <martinvonz@gmail.com>]

On Thu, Jan 21, 2021 at 4:28 AM Jeff King <peff@peff.net> wrote:
>
> On Fri, Jan 15, 2021 at 04:50:08PM -1000, Martin von Zweigbergk wrote:
>
> > > > I do this often enough to wonder if I should write a small "filter"
> > > > that I can pipe a whole "diff3" <<< ... ||| ... === ... >>> region
> > > > to and convert it into to diffs, but not often enough to motivate
> > > > me to actually write one ;-).
> > >
> > > I would definitely have found that useful before (usually when one side
> > > made a tiny one-line change and the other side deleted or drastically
> > > changed a huge chunk).
> >
> > FYI, I added something similar to Mercurial recently. Instead of two
> > diffs, it shows one snapshot and one diff. See
> > https://phab.mercurial-scm.org/D9551 for details. I've used it for a
> > few weeks and it seems to be working pretty well. The drawback is
> > mostly when you want to keep the side with the diff and ignore the
> > other side, since you'll then have to drop the lines prefixed with "-"
> > and then enter column-selection mode or something and delete the first
> > character on each remaining line.
>
> I've used the script I posted earlier in the thread several times in the
> last 6 months or so, by replacing the conflict markers in the file I'm
> resolving with the new output (basically "%!magic-diff3" in vim).
>
> It is helpful. My biggest complaint is cleaning up the diff from the
> marker after viewing it. In most cases where it's helpful, one side made
> a large change (say, deleting or moving a big chunk of code) and the
> other made a small one (tweaking one line in the moved chunk). The small
> diff is useful, but the big one is not. And then after having viewed it,
> I have to remove the whole big diff in my editor.
>
> (It sounds like yours _replaces_ the conflict marker with the diff,
> which is why you have to edit the diff. Mine is showing it in addition,
> so you have to delete the diff).

Yes, that's correct. It replaces the base and one side of the conflict
marker by a diff (and leaves the other side as a snapshot).

> I think rather than thinking of these as expanded conflict markers, it
> would probably be a more useful workflow to just look at the diff in a
> separate command (so just show the conflicts, not everything else, and
> just show the diff). I suspect it could be made pretty nice with some
> simple editor support (e.g., open a new buffer in the editor showing the
> diff for just the current hunk, or even the current _half_ of the hunk
> you're on).

At some point it seems better to delegate to a proper merge tool. You
said that you use vim, so I'm a little surprised that you use conflict
markers instead of using vimdiff. I don't use vim and I've never
really used vimdiff. I still use conflict markers, mostly out of
habit, but also because I usually run in a tmux session on a remote
machine. I feel like I should try to switch to meld.