Re: [PATCH] git-rebase--merge: don't include absent parent as a base
- From
Ben Woosley <ben.woosley@gmail.com>
- Date
- Apr 20, 2016, 21:19 UTC
- Message-ID
- <CAC5gnOxFVT=Y-YURxQxnT3Qng162=jogoZMEYJdN1jz8SmJtCg@mail.gmail.com>
- In-Reply-To
- <xmqq1t60ugoi.fsf@gitster.mtv.corp.google.com>
It's helpful in the case where a bit of code has been detached from its history by way of copying the files and starting a new repo, where development continues. If you want to reunite the new history with the prior history, while preferring the new history, you need to `rebase -Xtheirs` the new branch onto the old.
Best, Ben
On Wed, Apr 20, 2016 at 2:13 PM, Junio C Hamano <gitster@pobox.com> wrote:
Show 71 quoted lines
> Ben Woosley <Ben.Woosley@gmail.com> writes:
>
>> From: Ben Woosley <ben.woosley@gmail.com>
>>
>> Absent this fix, attempts to rebase an orphan branch with --strategy recursive
>> will fail with:
>>
>> $ git rebase ORPHAN_TARGET_BASE -s recursive
>> First, rewinding head to replay your work on top of it...
>> fatal: Could not parse object 'ORPHAN_ROOT_SHA^'
>> Unknown exit code (128) from command: git-merge-recursive ORPHAN_ROOT_SHA^ -- HEAD ORPHAN_ROOT_SHA
>>
>> To fix, this will only include the rebase root's parent as a base if it exists,
>> so that in cases of rebasing an orphan branch, it is a simple two-way merge.
>>
>> Note the default rebase behavior does not fail:
>>
>> $ git rebase ORPHAN_TARGET_BASE
>> First, rewinding head to replay your work on top of it...
>> Applying: ORPHAN_ROOT_COMMIT_MSG
>> Using index info to reconstruct a base tree...
>>
>> Signed-off-by: Ben Woosley <ben.woosley@gmail.com>
>> ---
>> git-rebase--merge.sh | 4 +++-
>> t/t3402-rebase-merge.sh | 9 +++++++++
>> 2 files changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/git-rebase--merge.sh b/git-rebase--merge.sh
>> index 2cc2a6d..8d43db9 100644
>> --- a/git-rebase--merge.sh
>> +++ b/git-rebase--merge.sh
>> @@ -67,7 +67,9 @@ call_merge () {
>> GIT_MERGE_VERBOSITY=1 && export GIT_MERGE_VERBOSITY
>> fi
>> test -z "$strategy" && strategy=recursive
>> - eval 'git-merge-$strategy' $strategy_opts '"$cmt^" -- "$hd" "$cmt"'
>> + # If cmt doesn't have a parent, don't include it as a base
>> + base=$(git rev-parse --verify --quiet $cmt^)
>> + eval 'git-merge-$strategy' $strategy_opts $base ' -- "$hd" "$cmt"'
>
> Makes sense to me. It is not clear if such a merge without common
> ancestor is all that useful, but as it is mechanically possible,
> I do not see a reason to forbid it.
>
>> rv=$?
>> case "$rv" in
>> 0)
>> diff --git a/t/t3402-rebase-merge.sh b/t/t3402-rebase-merge.sh
>> index 8f64505..488945e 100755
>> --- a/t/t3402-rebase-merge.sh
>> +++ b/t/t3402-rebase-merge.sh
>> @@ -85,6 +85,15 @@ test_expect_success 'rebase -Xtheirs' '
>> ! grep 11 original
>> '
>>
>> +test_expect_success 'rebase -Xtheirs from orphan' '
>> + git checkout --orphan orphan-conflicting master~2 &&
>> + echo "AB $T" >> original &&
>> + git commit -morphan-conflicting original &&
>> + git rebase -Xtheirs master &&
>> + grep AB original &&
>> + ! grep 11 original
>> +'
>> +
>> test_expect_success 'merge and rebase should match' '
>> git diff-tree -r test-rebase test-merge >difference &&
>> if test -s difference
>>
>> --
>> https://github.com/git/git/pull/228