Re: [PATCH 0/2] [RFC] Switch default merge backend from recursive to ort

[Jeff King <peff@peff.net>]

On Sun, Aug 01, 2021 at 12:07:39AM +0000, Elijah Newren via GitGitGadget wrote:

> This is an RFC series designed to spur feedback about switching the default
> merge backend (reviewing the patches is of secondary importance at this
> point). Some questions:
> 
>  * Are there things others want before this series is considered for
>    inclusion?
>  * What kind of timeline do others think is reasonable?
>  * Would it be beneficial to let this series sit in 'next' for an extended
>    duration to gain more feedback?

It looks like others gave some more specific review on the patches, but
on the meta-topic of "do we switch, and when", my response is: yes, and
soon. :)

Having watched the development of merge-ort, plus all of the weird
corner cases in merge-recursive we've seen over the years (many of which
you found and added tests for while working on merge-ort!), my gut
feeling is that the switch is _much_ more likely to fix problems people
might see in the wild rather than cause them.

It would make sense to me to do the switch in 'next' early in the
post-v2.33 cycle. It can cook there for a bit, but I think we have found
that it's much more likely to see actual use once it hits 'master'. So I
don't see a particular reason to have it sit in 'next' for a long time.
We should get as much exposure in 'master' during the v2.34 cycle as
possible.

The nice thing is that the two strategies can co-exist. So if it does
turn out to have any regressions, it's an easy revert to switch back,
and even post-release users can switch at runtime. We have pull.twohead,
but I don't think we have an equivalent that would impact a bare "git
merge" or "git rebase -m". Maybe it would be worth adding those as an
escape hatch?

-Peff