When resolving conflicts during a rebase, is there a native command for accepting both changes?

Question

A merge conflict occurred during a rebase, and Git is now asking me to resolve the patch. In cases where both changes are acceptable, how do I tell Git to accept both changes without having to modify the file myself?

E.g. when both changes are acceptable:

<<<<<<< HEAD
const foo = require('./foo');
=======
const bar = require('./bar');
>>>>>>> some commit message

git: can I accept both changes in a merge conflict without editing files? suggests a way to do this for a very specific case without using Git, but I'm looking to do this with native Git commands. A comment mentions doing a union merge, but I couldn't find docs around how to do this in this scenario.

Answer 1

To do a union merge, you must first extract all three inputs:

git show :1:$path > base
git show :2:$path > ours
git show :3:$path > theirs

(these file names are purely for illustration—in practice you would need to generate a unique temporary file name for most of these file), then run git merge-file:

git merge-file --union ours base theirs

The merged result is now in the file named ours; base and theirs may be discarded.

(Git probably should include a script that does the three extractions, runs git merge-file with any of the ours, theirs, or union options, and puts the result into the work-tree for inspection. It doesn't, but I think it should.)

You must be very careful with union-merge, as it always thinks it succeeded, even if it made a mess of the result.