Re: Confusing (maybe wrong?) conflict output with ort

Excerpts from Elijah Newren's message of December 2, 2021 6:58 pm:

Hi,

On Thu, Dec 2, 2021 at 11:08 AM Alex Xu (Hello71) [off-list ref] wrote:

quoted

Hi all,

After upgrading to git 2.34.1, I tried to rebase [0] onto [1], but
encountered "strange" conflict results.

git rebase -s recursive main produces [[RECURSIVE]]. It is roughly what
I expected to be output. If I take all the changes from the upper
section of the conflict, my changes will be effectively undone. If I
take all the changes from the lower section, then the upstream changes
will be undone.

In general, this does not work.  The only time it can work is if every
region of the code considered by the three-way content merge ended up
with conflicts.  (If any of those regions had automatically resolvable
changes, then after taking just the upper section(s) or just the lower
section(s) of each conflict would still result in a file that is a
mixture of changes from both sides due to the automatically resolvable
chunks that the merge already handled.)

quoted

On the other hand, running git rebase -s ort main produces [[ORT]]. I am
unsure if it is wrong, strictly speaking, but it is certainly unexpected
and difficult for me to resolve. Selecting the upper section of the
conflict does erase my changes, as before, but selecting the lower
section results in syntactically incorrect code (foreach is ended by
endif). The diff3 output makes even less sense to me.

The output from using ort is identical to that obtained by

   git rebase -s recursive -Xdiff-algorithm=histogram ...

on your testcase; i.e. this is due to a difference between the
histogram and myers diff algorithms.
(recursive defaults to using myers diff; ort uses histogram diff.)

[ ... ]

Does that help explain things?

Hm, I did try both default and patience and it didn't make a difference. 
git rebase -s recursive -Xdiff-algorithm=histogram master does produce 
the same result as ort though. I probably should have tried that first. 
Thanks for the explanation though, that's very helpful!

Cheers,
Alex.