将两个合并提交压缩为一个合并提交？

Question

I have the following scenario:

* a278b6b (HEAD -> feature1) Change i to j
| * c9550d0 (feature3) Print only odds
|/
| * befb5e9 (feature2) 2*z in baz loop
|/
* aa36658 Print only evens

Now, what I would like to do is merge the feature1 , feature2 , and feature3 branches together into a new branch, so that this new commit contains all information from the 3 branches. Normally you could just do an octopus merge and get exactly what I'm looking for, but in this case, there are merge conflicts between the three branches that need to be resolved manually. So, after merging the branches one at a time in order to resolve all merge conflicts, I'm left with:

*   6679d6c (HEAD -> DI) merge feature3
|\
| * c9550d0 (feature3) Print only odds
* |   5b03abb merge feature2
|\ \
| * | befb5e9 (feature2) 2*z in baz loop
| |/
* / a278b6b (feature1) Change i to j
|/
* aa36658 Print only evens

where DI is the branch that all three feature branches will be merged into.

The problem is that now I have two merge commits here: 5b03abb and 6679d6c . I'd like for there to only be a single merge commit (for cleanliness & maintenance), but the merge conflicts mean that I can't just do a straight octopus merge. Is there a way to somehow squash the two merge commits into the same commit like you would do for standard commits, or some other merge strategy that I should be using in order to get a single merge commit with 3 parents?

Answer 1

Create a commit from thin air using the original branches as parents and the final tree as.... the tree :

git commit-tree -p a278b6b -p c9550d0 -p befb5e9 -m "some merge" 6679d6c^{tree}

That will print a commit ID. Set the branch you want there, say, main:

git branch -f main the-id-from-previous-command