How do I merge my local uncommitted changes into another Git branch?

Stashing, temporary commits and rebasing may all be overkill. If you haven't added the changed files to the index, yet, then you may be able to just checkout the other branch.

git checkout branch2

This will work so long as no files that you are editing are different between branch1 and branch2. It will leave you on branch2 with you working changes preserved. If they are different then you can specify that you want to merge your local changes with the changes introduced by switching branches with the -m option to checkout.

git checkout -m branch2

If you've added changes to the index then you'll want to undo these changes with a reset first. (This will preserve your working copy, it will just remove the staged changes.)

git reset

WARNING: Not for git newbies.

This comes up enough in my workflow that I've almost tried to write a new git command for it. The usual git stash flow is the way to go but is a little awkward. I usually make a new commit first since if I have been looking at the changes, all the information is fresh in my mind and it's better to just start git commit-ing what I found (usually a bugfix belonging on master that I discover while working on a feature branch) right away.

It is also helpful—if you run into situations like this a lot—to have another working directory alongside your current one that always have the master branch checked out.

So how I achieve this goes like this:

1. git commit the changes right away with a good commit message.
2. git reset HEAD~1 to undo the commit from current branch.
3. (optional) continue working on the feature.

Sometimes later (asynchronously), or immediately in another terminal window:

1. cd my-project-master which is another WD sharing the same .git
2. git reflog to find the bugfix I've just made.
3. git cherry-pick SHA1 of the commit.

Optionally (still asynchronous) you can then rebase (or merge) your feature branch to get the bugfix, usually when you are about to submit a PR and have cleaned your feature branch and WD already:

1. cd my-project which is the main WD I'm working on.
2. git rebase master to get the bugfixes.

This way I can keep working on the feature uninterrupted and not have to worry about git stash-ing anything or having to clean my WD before a git checkout (and then having the check the feature branch backout again.) and still have all my bugfixes goes to master instead of hidden in my feature branch.

IMO git stash and git checkout is a real PIA when you are in the middle of working on some big feature.

Since your files are not yet committed in branch1:

git stash
git checkout branch2
git stash pop

or

git stash
git checkout branch2
git stash list       # to check the various stash made in different branch
git stash apply x    # to select the right one

Above is the longer more explicit version of rbento's answer:

git stash
git stash branch branch2

It uses:

git stash branch <branchname> [<stash>]

• Creates and checks out a new branch named <branchname> starting from the commit at which the <stash> was originally created,
• applies the changes recorded in <stash> to the new working tree and index.

If that succeeds, and <stash> is a reference of the form stash@{<revision>}, it then drops the <stash>.

This is useful if the branch on which you ran git stash push has changed enough that git stash apply fails due to conflicts.
Since the stash entry is applied on top of the commit that was HEAD at the time git stash was run, it restores the originally stashed state with no conflicts.

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As commented by benjohn (see git stash man page):

To also stash currently untracked (newly added) files, add the argument -u, so:

git stash -u

A shorter alternative to the accepted answer would be:

Temporarily move the changes to a stash.

1. git stash

Create and switch to a new branch and then pop the stash to it in just one step.

2. git stash branch new_branch_name

Then just add and commit the changes to this new branch.