How to inject a commit between some two arbitrary commits in the past when there is multiple branch above?

Question

Suppose I have the following commit history on my local-only branch:

A -- B -- C -- D  
            \- E

How do I insert a new commit between A and B and keep both D and E above C?

yes, in the answer I need to choose what branch (let say E or D) I want to rebase on A. But I want to rebase D and E at the same time, to avoid breaking the two branches and keep the common C. I know I can choose E and rebase -i on A, and then rebase --onto to add the E branches on C, but when there is lot of above branches, it's a lot of work. — jota, Dec 02 '18 at 21:33
Yes, it is a lot of work because git does not directly support this kind of workflow. — Lasse V. Karlsen, Dec 02 '18 at 21:39
I thought git allow history rewritting to have a clean project. So this is only true when I am on a single branch? after diverging there is no way to easily alter the history? — jota, Dec 02 '18 at 21:55
Your solution is to use `git replace` and then `git filter-branch` (but hash of all the commits after A will change) — Philippe, Dec 02 '18 at 22:09
git replace may solve the problem, but the goal here is to have a clean history that may be transferable to other project. I'm a bit afraid of the mess of replace. I Will try anyway. — jota, Dec 02 '18 at 22:53

score 1 · Answer 1 · edited Jan 15 '21 at 17:03

1

You can do an interactive rebase on your first branch to inject your commit and then do a rebase onto to apply this changes to your other branch.

Assuming you have:

A -- B -- C -- D  
           \-- E

After injecting your commit into your first branch (following the How to inject a commit between some two arbitrary commits in the past) you would have something like:

A -- A2 -- B' -- C' -- D'
 \-- B  -- C  -- E

Than you can do a rebase --onto from your another branch, to apply the changes it:

git rebase --onto C' E branch2

So you final result would be:

A -- A2 -- B' -- C' -- D'
                   \-- E'

edited Jan 15 '21 at 17:03

abarisone

answered Dec 02 '18 at 22:15

Aurora Wang

To better understand `rebase --onto` you can read [here](https://stackoverflow.com/q/29914052/10657880). – Aurora Wang Dec 02 '18 at 22:17
1

Thank you for the answer, but as I said in this comment https://stackoverflow.com/questions/53584752/how-to-inject-a-commit-between-some-two-arbitrary-commits-in-the-past-when-there/53585114#comment94033440_53584752 I know this solution, but it can be a huge work if there is lot of branches above C. I'm looking for a solution that does the same, but whithout the "104 branches, 104 rebase to do". Maybe the only solution is scripting. – jota Dec 02 '18 at 22:21
Have you seen [How can I rebase multiple branches at once?](https://stackoverflow.com/q/23386318/10657880)? There are some utilities made for this purpose. – Aurora Wang Dec 02 '18 at 22:23
thanks, that's may be a solution, but I can't manage to make it work. Assertion failed, some name are undefined. May be it's an unfinished work. – jota Dec 02 '18 at 22:58

score 0 · Answer 2 · answered Dec 03 '18 at 00:16

0

Stop the madness :) and just add the commit to D and then either merge or cherry-pick it to E

A -- B -- C -- D -- X 
           \-- E -- X

answered Dec 03 '18 at 00:16

tymtam

Yes I now that your solution is the productive one, where I can go back to work after two cherry-pick. But what if the ABC commit are common to hundreds of branches?can't I extend the ABC root to ABB'C in one operation? – jota Dec 03 '18 at 12:59
Yes it's true, but what if there is 23 branches aboce C? – jota Dec 03 '18 at 17:15
...than it's even more risky to do it before C. How would you test a change in 23 branches? – tymtam Dec 04 '18 at 06:20
Ok I agree that seem to be a bad idea. But in this precise case I try to insert a commit that does an add in the makefile, and I want this new little feature everywhere when I crusing my history. But in a more general situation the intergration test are here for that, right? – jota Dec 04 '18 at 16:23

2 Answers2