CODEWITHSUNDEEP
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mogoh
mogoh

Reputation: 1073

Merge two branches and keep both chages in sperated dirs

I have two branches, branch_a and branch_b.

branch_a:

dir_1/a lot of files

branch_b:

dir_1/a lot of changes

I now think it would be best if instead of just merging, I keep both directories for now.

Desired result:

dir_1/a lot of files
dir_2/a lot of changes

Of cause I could just copy all the files from branch_b into dir_2, but that would lose the history. Is there a "git-way" to solve this?

Upvotes: 1

Views: 44

Answers (1)

Mad Physicist
Mad Physicist

Reputation: 114440

If possible, I would avoid having two copies of your content side-by-side at all. It will make merging the two back together more involved. However, without more information, I can not suggest an alternative, so here goes.

I am assuming that branch_a and branch_b have some common ancestor commit, but are not simple fast-forwards of each other. If they are, this likely won't work because any attempt to merge will result in a fast-forward, including the rename step.

In branch_a, which contains the "legacy" version, move dir_1 to its intended path:

$ git checkout branch_a
$ git mv dir_1 dir_1-legacy
$ git commit -m 'Created separate folder'

I would recommend making a separate branch for the merged result, so you can do something like

$ git checkout -b branch_transition branch_b

If you prefer to just update branch_b with the result, just do

$ git checkout branch_b

In either case, you can now merge in the two folders, preserving the history of each:

$ git merge branch_a
CONFLICT (modify/delete): dir_1/XXX deleted in a and modified in HEAD. Version HEAD of dir_1/XXX left in tree.
...
Automatic merge failed; fix conflicts and then commit the result.
$ git add dir_1
$ git commit -m 'Merged divergent paths'

The step git add dir_1 is necessary in response to the failed automatic merge, which happens to be exactly what you want under the circumstances.

I would also recommend bumping branch_a back one commit, so that any future changes in it do not operate on the dir_1-legacy folder:

git checkout branch_a
git reset --hard HEAD~

Re-merging

Once your transition is complete, you can re-merge the two folders using a similar technique. Let's say that you are on branch_transition, and would like to merge the two folders together. You can do this by creating a new temporary branch, deleting one version of the folder in each of the branches, renaming one, and merging:

git checkout branch_transition
# Create temp branch to hold the legacy code
git checkout -b temp_transition
git rm dir_1
git mv dir_1-legacy dir_1
git commit -m 'Converted legacy to baseline'

# Set up merge on the transition branch
git checkout branch_transition
git rm dir_1-legacy

# Do the merge
git merge --strategy ours temp_transition
git branch -d temp_transition

You will need to use --strategy ours to get the non-legacy version to trump the legacy one according to my experiments. This is not the same as doing --strategy recursive -X ours, which does not work as intended.

Upvotes: 1

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