emacs - Using ediff as git mergetool

Question

I would like to be able to use ediff with "git mergetool".

I found some patches that alter the source code, which I don't want to do. Instead, I'd like to add ediff support with my .gitconfig.

I know git has builtin support for emerge, but I prefer ediff.

I attempted to add these lines to my .gitconfig:

[mergetool "ediff"]
    cmd = emacs --eval "(ediff-merge-files-with-ancestor "$LOCAL" "$REMOTE" "$BASE" nil "$MERGED")"

But when I try to run this with "git mergetool --tool=ediff", I get this:

eval: 1: Syntax error: "(" unexpected

What am I doing wrong?

Answer 1

I use a a more complicated command. As far as I remember I got it from this thread http://kerneltrap.org/mailarchive/git/2007/6/28/250230 (probably the same as what you are referring to).

[mergetool.ediff]
    cmd = emacs --eval "
(progn
  (defun ediff-write-merge-buffer ()
    (let ((file ediff-merge-store-file))
      (set-buffer ediff-buffer-C)
      (write-region (point-min) (point-max) file)
      (message "Merge buffer saved in: %s" file)
      (set-buffer-modified-p nil)
      (sit-for 1)))
  (setq ediff-quit-hook 'kill-emacs
        ediff-quit-merge-hook 'ediff-write-merge-buffer)
  (ediff-merge-files-with-ancestor "$LOCAL" "$REMOTE"
                                   "$BASE" nil "$MERGED"))"

Note that I have split this across several lines to increase readability and escaped the newline with so git config considers it as a single line.

I usually use emacsclient to edit e.g. commit messages. The above mergetool configuration unfortunately does not use emacsclient, and when I tried to get it to work with emacsclient I ran in to various problems including the fact that emacsclient returned right away.

But you just reminded me of that issue, so I might work on fixing that problem soon. However if someone else already found a solution that would be great of course ;-)