What is Git Merge Squash?

git merge --squash is a Git operation that allows you to take all the changes from one branch and squash them into a single commit on top of the branch you're currently on. This is different from a regular merge, where all commits from the feature branch are preserved. By squashing them into one, you're essentially saying, "Take all these changes as if they happened in a single moment."

Why Use Git Merge Squash?

Clean History

One of the main reasons to use squash merging is to maintain a clean and linear project history.

Easy Reverts

Because all changes from the feature branch are condensed into a single commit, reverting changes is straightforward.

Simplified Code Reviews

When changes are packed into a single commit, it makes the code review process much easier.

How to Perform Git Merge Squash

Here are the steps to perform a squash merge:

1. Checkout to the Base Branch: Make sure you are on the branch you want to merge into.

   git checkout master

2. Perform the Squash Merge: Use the git merge --squash command followed by the feature branch name.

   git merge --squash feature-branch

3. Commit the Changes: Finally, commit the changes.

   git commit -m "Squashed commit from feature-branch"

Common Pitfalls

Conflicts

Just like regular merges, squash merges can also lead to conflicts, which you will have to resolve manually.

Not Suitable for All Scenarios

Squash merges are not ideal for branches with extensive history or for branches intended to be temporary.

When Not to Use Git Merge Squash

• When you want to preserve the context provided by multiple commits.

• When changes are too extensive and need to be reviewed individually.

Alternatives to Git Merge Squash

• Regular Merge: Keeps the entire commit history of the feature branch.

• Rebase: Moves the feature branch on top of the master, creating a linear history without squashing.

FAQ

Q: What does git merge --squash actually do?

A: The git merge --squash command takes all the commits from a feature branch and squashes them into a single commit on your current branch. This allows you to have a single commit that includes all changes, rather than a commit for each change made in the feature branch.

Q: How is git merge --squash different from git rebase?

A: While both can be used to create a linear history, git rebase moves the entire feature branch to the tip of the master branch, preserving individual commits. git merge --squash, however, squashes all changes into one single commit, making the history cleaner but losing the granularity of individual commits.

Q: Can I squash merge into any branch, or does it have to be the main branch?

A: You can squash merge into any branch, not just the main or master branch. The choice of the target branch depends on your workflow.

Q: How do I resolve conflicts during a squash merge?

A: Conflict resolution during a squash merge is similar to a regular merge. You'll need to manually edit the conflicting files, mark them as resolved, and then commit the changes.

Q: Can I undo a squash merge?

A: Yes, you can undo a squash merge by running git reset --hard <previous_commit_hash>. However, be cautious with this command, especially on shared branches, as it rewrites history.

Q: Is git merge --squash recommended for long-running branches?

A: Generally, no. Squash merges are better suited for feature branches that are relatively short-lived and will be merged and deleted soon after.

Q: Can I pick which commits to squash?

A: The git merge --squash command squashes all commits from the feature branch. If you want to pick specific commits, you should look into using git rebase -i for an interactive rebase.

Q: What happens to the feature branch after a squash merge?

A: The feature branch remains unchanged after a squash merge. You can choose to delete it manually if it's no longer needed.

Q: Can I use squash merge in GUI Git clients?

A: Yes, most GUI Git clients offer an option to perform squash merges. The exact steps can differ between clients.

Q: Is squash merging a good practice for open-source projects?

A: The use of squash merging in open-source projects can be contentious. Some maintainers prefer a clean history, while others prefer to preserve the entire history for context. It's best to check the project's contribution guidelines.