Re: [PATCH v2 2/7] add tests for rebasing with patch-equivalence present

On Wed, May 29, 2013 at 12:09 AM, Johannes Sixt [off-list ref] wrote:

Am 5/29/2013 8:39, schrieb Martin von Zweigbergk:

quoted

+#       f
+#      /
+# a---b---c---g---h
+#      \
+#       d---G---i

...

quoted

+test_run_rebase () {
+     result=$1
+     shift
+     test_expect_$result "rebase $* --onto drops patches in onto" "
+             reset_rebase &&
+             git rebase $* --onto h f i &&
+             test_cmp_rev h HEAD~2 &&
+             test_linear_range 'd i' h..

Isn't this expectation wrong? The upstream of the rebased branch is f, and
it does not contain G. Hence, G should be replayed. Since h is the
reversal of g, the state at h is the same as at c, and applying G should
succeed (it is the same change as g). Therefore, I think the correct
expectation is:

                test_linear_range 'd G i' h..

Good question! It is really not obvious what the right answer is. Some
arguments in favor of dropping 'G':

1. Let's say origin/master points to 'b' when you start the 'd G i'
branch. You then send the 'G' patch to Junio who applies it as 'g'
(cherry-picking direction is reversed compared to figure, but same
effect). You then "git pull --rebase" when master on origin points to
'h'. Because of the cleverness in 'git pull --rebase', it issues 'git
rebase --onto h b i'. In this case it's clearly useful to have the
patch dropped.

2. In the test a little before the above one, we instead do 'git
rebase --onto f h i' and make sure that the 'G' is _not_ lost. In that
case it doesn't matter what's in $branch..$upstream. Do we agree that
$branch..$upstream should never matter (instead, $upstream is only
used to find merge base with $branch)? Do we also agree that 'git
rebase a b' should be identical to 'git rebase --onto a a b'? Because
'git rebase h i' should clearly drop 'G', then so should 'git rebase
--onto h h i'. Then, if we agreed that $branch..$upstream doesn't
matter, 'git rebase --onto h f i' should behave the same, no?


The set of commits to rebase that I was thinking of using was
"$upstream..$branch, unless equivalent with patch in $branch..$onto".
But I'm not very confident about my conclusions above :-)


Martin