Change branch base

I've a tree like this:

(commit 1) - master
                \-- (commit 2) - (commit 3) - demo
                                                \-- (commit 4) - (commit 5) - PRO

and I have to move the PRO branch to master

(commit 1) - master
                |-- (commit 2) - (commit 3) - demo
                \-- (commit 4) - (commit 5) - PRO

I've tried a git rebase master from PRO branch, but nothing happens.

To clarify: I was working in master and then I had to make a product demo (git checkout -b demo and some commits). Then, by mistake, I create another branch from demo (git checkout -b PRO and some commits) and now I need to move PRO branch to master and leave demo intact. At the end, both demo and PRO will hang from master.

Solution 1:

Assuming newBase is the branch you want to move your commits onto, oldBase is the old basis for your branch, you can use --onto for that:

git rebase --onto newBase oldBase feature/branch

Given your case:

git checkout PRO # Just to be clear which branch to be on.
git rebase --onto master demo PRO

Basically, you take all the commits from after demo up to and including PRO, and rebase them onto the master commit.

Solution 2:

I will try to be as generic as I can be. First, be sure that you are on the desired branch:

git checkout current-branch

Then use the following command (where new-base-branch is the branch which you want to be your new base, and current-base-branch is the branch which is your current base.)

git rebase --onto new-base-branch current-base-branch

If you do not have conflicts, then great - you are done. If you do (in most cases), then please read on.

Conflicts might arise, and you will have to resolve them manually. Git now tries to do a "3-way merge" between your current-branch, current-base-branch and new-base-branch. Roughly this is how git will work internally:

1. Git will first rebase the current-base-branch on top of the new-base-branch. There might be conflicts; which you will have to resolve manually. After that is done, you usually do git add . and git rebase --continue. It will create a new temporary commit temp-commit-hash for this.

2. After this, Git will now rebase your current-branch on top of temp-commit-hash. There might be further conflicts and again you will have to resolve them manually. Once done, you continue again with git add . and git rebase --continue, after which you have successfully rebased your current-branch on top the new-base-branch.

Note: If you start to mess up, then you can do git rebase --abort anytime during the rebase process and get back to the starting point.

Solution 3:

Checkout to PRO branch, Copy the oldest (commit4) and latest (commit5) commit hashes of this branch and paste somewhere else:

$ git checkout PRO
$ git log            # see the commit history
# copy the oldest & latest commit-hash 

Delete the PRO branch (keep a backup just for safety). Create and checkout to a new PRO branch from master:

$ git branch PRO.bac    # create a new branch PRO.bac = PRO as backup

$ git checkout master
$ git branch -D PRO     # delete the local PRO branch
$ git checkout -b PRO   # create and checkout to a new 'PRO' branch from 'master'

Take (cherry-pick) the range of commits of Previous PRO branch into the new PRO branch:

$ git cherry-pick commit4^..commit5   # cherry-pick range of commits
# note the '^' after commit4

Now, if all is ok, then do force (-f) push to remote PRO branch and delete local PRO.bac branch:

$ git log                  # check the commit history

$ git push -f origin HEAD  # replace the remote PRO by local PRO branch history
# git branch -D PRO.bac    # delete local PRO.bac branch

Solution 4:

I had a slightly different approach using reset and stashes that avoids deleting and re-creating branches as well as eliminating the need to switch branches:

$ git checkout PRO
$ git reset commit4 # This will set PROs HEAD to be at commit 4, and leave the modified commit 5 files in ur working index
$ git stash save -m "Commit message"
$ git reset commit3
$ git stash save -m "Commit message"
$ git reset master --hard
$ git stash pop
$ git stash pop
$ git push --force # force if its already been push remotely

By resetting the branch on a commit-by-commit basis your basically just rewinding that branches history a commit at a time.