Fixing PRs after rebasing

TODO: collapasable, copyable, download, etc

I had a long feature branch feature-base. I then made a branch fix1 against feature-base. Then I made a branch fix2 against fix1. Lastly I made another PR in fix3 that is based off of fix2.

I wanted to update all of these branches with the newest code from main.

I did this:

Locally in feature-base I did fetch origin, git rebase origin/main.

Next, in fix1 locally, I did git rebase feature-base. Next, in fix2 locally, I did git rebase fix1. Next, in fix3 locally, I did git rebase fix2.

I pushed these branches up...

The different PRs build on each other, so the PR for fix3 has it's base as fix2, etc.

My pull request for feature-base says "65" commits, when I only had one. Somehow the rebase commits are showing up. Files changed is a list of many files otuside of what I did.

Same for fix1 - fix3.

How can I get this back so that the PR only shows the commits and files that are actually part of that branch? It seems like the rebasing process has caused commits from the main branch to be replayed in your feature and fix branches, leading to the pull requests displaying an inflated number of commits and potentially including changes that were not part of your original work. This is a common scenario when rebasing branches that have diverged significantly from their new base.

Here's how you can clean this up to ensure that each PR only shows the commits and files that are actually part of that branch:

1. Reset your branches to their state before the rebase

First, if you haven't pushed the rebased branches to the remote or if you can force push safely (ensuring no one else is working on the same branches), you might want to reset your branches to the state before the rebase. You can use git reflog to find the commit SHA of the state before the rebase for each branch and then reset it:

# For each branch, find the commit to reset to
git reflog feature-base
# Reset the branch to the desired state
git reset --hard <commit-sha-before-rebase>

# Repeat for fix1, fix2, and fix3

2. Cherry-pick your changes onto new branches from the updated main

Instead of rebasing directly, especially if the branches have been pushed and the history is complex, consider creating new branches from the updated main and cherry-pick your changes onto these new branches. This gives you more control and avoids the complexity of a rebase gone wrong.

# Update your local main and create a new branch
git checkout main
git pull origin main
git checkout -b feature-base-new

# Find the SHA of the commits you want to move
git log --oneline feature-base

# Cherry-pick your commits onto the new branch
git cherry-pick <commit-sha>

# Repeat the process for fix1, fix2, and fix3, basing each new branch on the updated predecessor

3. Force push the corrected branches

Once you have your branches corrected locally with only the commits that belong to them, you can force push these changes to update the remote branches. Note that force pushing can disrupt others working on the same branch, so communicate with your team before doing this.

git push origin feature-base-new:feature-base --force
# Repeat for fix1, fix2, and fix3 with their respective new branches

4. Update your pull requests

If your PRs are automatically closed due to the branch changes or if they still don't look correct, you may need to open new PRs from your corrected branches. Ensure the base of each PR is set correctly (e.g., the base of fix1 should be feature-base, fix2 should be based on fix1, etc.).

Conclusion

This approach lets you cleanly apply your changes on top of an updated main without the messy history that rebasing can sometimes introduce. Remember, rebasing rewrites history, which is useful for keeping a linear project history but can cause issues like you've experienced when branches have already been pushed or shared with others.I have already pushed to the remoteGiven that you've already pushed the rebased branches to the remote, and assuming force pushing is an option (with caution and after coordinating with your team), you can still clean up your branches to reflect only the changes you've made, relative to the updated main branch. The approach involves resetting your local branches to a correct state and then force pushing these changes.

Step 1: Creating Correctly Based Branches

You can still follow the cherry-pick approach to create new branches off the updated main and then cherry-pick your changes onto these branches. This way, you ensure each branch only contains the commits that are relevant to that branch's work.

For Each Branch:

1. Create a new branch from the updated main:

   git checkout main
   git pull origin main
   git checkout -b <branch-name>-new
   

2. Cherry-pick your changes:

   Identify the commits in your original branch (e.g., feature-base, fix1, etc.) that are unique to your work and not part of the rebase noise.

   git log --oneline <original-branch-name>
   

   Then cherry-pick these commits onto your new branch:

   git cherry-pick <commit-sha>
   

   Repeat this for each commit that belongs to your changes. Resolve any conflicts as they arise.

3. Force push the new branch to replace the old one:

   After you've successfully cherry-picked your commits and have the branch in the state you want it:

   git push origin <branch-name>-new:<original-branch-name> --force
   

   This command replaces the remote branch with your newly created branch.

Step 2: Updating Pull Requests

After force pushing:

• If your PRs remain open, they should automatically reflect the new state of the branches. Ensure the base of each PR is correctly set to chain your changes as intended (e.g., fix1 → feature-base, fix2 → fix1, etc.).
• If you encounter any issues with the PRs, such as them not updating correctly or showing incorrect comparisons, consider closing the existing PRs and opening new ones with the correct bases and branches.

Communication and Coordination

Force pushing can alter the project history and potentially disrupt your team's workflow, especially if others have checked out or based their work on the branches you're modifying. It's essential to:

• Communicate your plans with your team before force pushing. Make sure everyone is aware of the changes and can prepare accordingly (e.g., resetting their local branches or checking out the new branch state).
• Coordinate the timing of your force pushes to minimize disruption, especially if your team is actively using the branches or if your repository has CI/CD pipelines that might be triggered by these changes.

Conclusion

This approach allows you to clean up your pull requests so that they only show the commits and files actually part of each branch's work. It requires careful handling and coordination but will result in a clearer, more manageable set of pull requests that accurately reflect your contributions.Instead... could I use merge to fix this instead?Yes, using merge instead of rebase to integrate the latest changes from main into your feature and fix branches can be a viable alternative, especially after you've already pushed the branches to remote and want to avoid the complexities of rewriting history. Merging keeps the history intact and can help avoid some of the pitfalls associated with rebasing already-pushed branches.

Here's how you can use merge to bring your branches up to date with main, while aiming to minimize confusion in your pull requests:

1. Merge main into Each Branch Sequentially

Starting with the base of your branch hierarchy (feature-base), merge the updated main into each branch in sequence, resolving any conflicts as they arise. This keeps each branch updated with the latest from main without altering the existing commits' SHA values.

For feature-base:

git checkout feature-base
git merge origin/main
# Resolve any conflicts if they exist
git push origin feature-base

Then for fix1, fix2, and fix3 sequentially:

# Assuming you're now moving to fix1
git checkout fix1
git merge feature-base
# Resolve any conflicts if they exist
git push origin fix1

# Repeat for fix2 and fix3, merging the immediately preceding branch

2. Handling Pull Requests

Since you're merging and not rebasing, your pull requests should automatically reflect the merge commits along with any conflict resolutions. The advantage here is that your PRs will not show an inflated commit count from main since those commits are merged, not rebased onto your branch. This approach keeps a linear progression of your work on top of the merged main changes, making it clear which changes are part of your feature and fix work.

3. Conflict Resolution

Merging might lead to conflicts, especially if the same parts of the code were modified in main and your branches. You'll need to carefully resolve these conflicts in each branch during the merge process. This step is crucial for ensuring that your changes are correctly applied on top of the latest main.

4. Benefits and Considerations

• Maintains History: Merging keeps the history of both branches, making it easier to understand the context of changes over time.
• Simplifies Collaboration: Since the commit history is not rewritten, it's safer for collaboration. Team members working on the same branches will not encounter issues due to rewritten history.
• Potentially More Merge Commits: One downside is the potential for more merge commits in your branch history, which can clutter your project history but also provides a complete picture of the integration points.

Conclusion

Merging is a more collaborative-friendly approach compared to rebasing for integrating changes from main into your work branches, especially after changes have been pushed. It preserves history and avoids the complications associated with force pushing rebased branches. However, it's essential to manage the merges carefully, resolve conflicts diligently, and communicate with your team about the changes to ensure a smooth integration process.Why did rebase pull in all these commits? Should I have used merge originally?The reason your rebase operation pulled in all those commits from main and caused confusion in your pull requests is rooted in how git rebase works and the state of your branch history. Understanding the differences between merge and rebase can help clarify why this happened and guide your decision on which to use in the future.

How git rebase Works

git rebase takes the commits in your branch and "replays" them on top of the branch you're rebasing onto. Here's why it pulled in all those commits:

1. Linear History: Rebasing is designed to create a linear project history. When you rebase feature-base onto origin/main, every commit from feature-base that does not exist in origin/main is reapplied, making it as if your work was done directly on top of the latest main.

2. Diverged Histories: If main has progressed significantly since feature-base branched off, rebasing feature-base onto origin/main will place all the new commits from main before your feature-base commits. This can make it look like there are many more commits in your branch, especially if main has a lot of activity.

3. Repeated Rebase: When you subsequently rebase fix1 on feature-base, fix2 on fix1, and so on, you're effectively layering these changes on top of each other. If feature-base now includes all recent main commits (due to its rebase), each subsequent rebase propagates these commits through your chain of branches.

Should You Have Used Merge Originally?

Whether to use merge or rebase depends on your workflow, project policies, and the specific situation. Here's a brief comparison to guide this decision:

• Merge:

  • Preserves the history as it happened, with merge commits showing points of integration.
  • Easier for collaborative branches since it doesn't rewrite history.
  • Can lead to a more complex history graph, making it harder to follow the project timeline.

• Rebase:

  • Creates a cleaner, linear history, as if you've been working on the latest version of the base branch all along.
  • Useful for local branch management before pushing, making your changes easier to integrate into a shared repository.
  • Riskier for shared branches since it rewrites history, potentially causing confusion or conflicts if not carefully managed.

Conclusion

• Rebase is powerful for maintaining a clean, linear history and simplifying the integration of local changes into a shared branch. It's particularly effective before sharing your work (pushing) or in workflows where a clean history is prioritized, and collaborators are comfortable managing the potential complexities of history rewriting.

• Merge is safer for integrating changes when branches have been shared or when preserving the exact history of changes and collaboration is important. It's the default choice for many workflows, especially when working on features collaboratively or when branches have a long life before integration.

In retrospect, if maintaining a straightforward history in your pull requests was a priority without showing all intervening commits from main, starting with a merge strategy for your feature and fix branches might have been more appropriate. This approach would have preserved the context of your changes relative to main without the overhead of dealing with rebase-induced complexities in the PR view.

Fixing PRs after rebasing created at Tue Jan 20 1970 18:05:45 GMT+0000 (Coordinated Universal Time)