Resolve git merge conflict by applying diff hunk to different file

Question

I have refactored a file by splitting into two files in one git branch, and someone else has made a different change to the original file on another git branch. This has produced a merge conflict in git when I tried to merge the second git branch into the first (which I did using magit). I have configured git to produce a 3-way diff surrounded by conflict markers in the file, and I have used C-c ^ = > to diff the original contents of the file and the second branch changes, which produces a vc-diff buffer.

How can I apply this vc-diff buffer to the second file, not the first file - either one hunk at a time, or all at once? I don't mind which way it is done, but I would prefer to do it one hunk at a time. (Bearing in mind that the line numbers will probably be different, but the surrounding text will be largely the same.)

Answer 1

Use C-c c-e in the vc-diff buffer to apply the diff to a file. Enter the target filename and press RET. This will launch ediff and attempt to apply the patch.

For me, the patch applied successfully without any hitches, so I just needed to press n a few times in the ediff frame to review the result, and then q to quit the ediff session.

Then return to the buffer for the first file and resolve the original conflict (in my case, by simply accepting my changes, as I had applied the changes from the other branch to the other file).