Hi all
On 15/07/2020 04:20, Denton Liu wrote:
Hi all,
On Tue, Jul 14, 2020 at 10:38:23PM +0200, Johannes Schindelin wrote:
To me the question is why are we looking at the upstream commits at all
with `--keep-base`? I had expected `rebase --keep-base` to be the same
as `rebase $(git merge-base [--fork-point] @{upstream} HEAD)` but
looking at the code it seems to be `rebase --onto $(git merge-base
@{upstream} HEAD) @{upstream}`. I didn't really follow the development
of this feature - is there a reason we don't just use the merge-base as
the upstream commit?
It behaves this way mostly for unimportant reasons. The first is that my
workflow before implementing this feature invoked running
`git rebase --onto master... master` and I wanted to replicate that.
More importantly, one feature of using the upstream I considered is
documented in t3431. Essentially, if we have the following graph,
A---B---D---E (master)
\
C*---F---G (side)
C was formerly part of master but master was rewound to remove C
running `git rebase --keep-base --fork-point master` would drop C.
Those are interesting questions, indeed.
And I dare to suspect that the answer is indeed: `--keep-base` really
should not only substitute `onto` but also `upstream` with the merge base.
I would be open to changing the behaviour since the commit dropping
isn't really a feature that I use very often. However, I am worried
about pulling the rug out from other people if they use it since this is
a documented feature in git-rebase.txt.
I think changing it to behave like
git rebase --onto $(git merge-base @{upstream} HEAD) \
$(git merge-base --fork-point @{upstream} HEAD)
when --fork-point is given would keep the existing behavior of dropping
commits when @{upstream} has been rewound without dropping cherry-picks.
--fork-point seems less useful when combined with --keep-base than when
used with a normal rebase as if @{upstream} has rewritten the commit
that the branch is based on rather than just dropping it we end up
dropping the original commit without getting the new version from
upstream as we would with a normal rebase. This could be surprising to
users if we keep --fork-point on by default with --keep-base.
Best Wishes
Phillip
Thanks,
Denton
Ciao,
Dscho
