Re: [PATCH v3 0/4] rebase: teach rebase --keep-base

[Denton Liu <liu.denton@gmail.com>]

On Sat, Apr 06, 2019 at 09:44:49PM +0200, Ævar Arnfjörð Bjarmason wrote:
> 
> On Mon, Apr 01 2019, Denton Liu wrote:
> 
> > Thanks again for your feedback, Ævar! I think we're both on the same page now.
> > Hopefully I've addressed all of your high-level concerns with this patchset and
> > we can move into a discussion on implementation detail.
> 
> Late in replying to this, have been off-list. This also applies for your
> v4.
> 
> The current version you have still doesn't explain the "Why would we
> redundantly rebase every time in this case..." question I had in
> https://public-inbox.org/git/87tvfma8yt.fsf@evledraar.gmail.com/
> 
> I *think* it's closer to "it was easier to implement this in terms of
> --onto, which happens to behave that way now" than "it must work this
> way for --keep-base", which is fair enough.

Correct, the reason why --keep-base was not lazy initially was because
"--onto did it that way". You are correct in that --keep-base should be
lazily rebasing so I changed --onto's behaviour in 3/4 because it would
also benefit from laziness. Thus, now --keep-base lazily rebases because
--onto also does.

> 
> Although I see when I forward-port my POC patch from that E-Mail that
> one test fails now, which is good, that wasn't the case before, but it
> looks like that might be testing something else than just the lazy
> behavior.

The test fails because the patch disables fork_point if --keep-base is
set. So, with the patch applied, C is rebased even though it is excluded
when fork_point is set.

> 
> It would be good to know in terms of commit message or (better) explicit
> tests so that if we teach these various rebase modes the same lazyness
> --fork-point uses in the future it's clear if that's OK or not.

Sorry, could you please clarify what you mean by the "lazyness
--fork-point uses"? I don't understand what laziness is introduced by
using --fork-point. Also, are the tests in t3432 not sufficient for
testing fast-forwarding (aka lazy) behaviour?

Thanks,

Denton