How does one ediff a current file--ie working tree--against an arbitrary version in some previous commit?
In this case, I'm interested in pulling in some, but not all, changes from a commit in another feature branch that was rejected.
2 Answers
I can't think of a one-step way to do this. The best I can come up with is
Type dr (
magit-diff), and set the range to the commitIf point is on the commit, you can copy it with C-w before calling dr.
In the diff buffer, go to the file you want and hit e (
magit-ediff-dwim)
Though you might consider doing away with the ediff step. You can hit v to reverse a hunk at point in the working tree.
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The twist is that the commit is in another branch; can you reverse from a commit not in the current one?– E BroCommented May 12, 2017 at 14:26
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Did you try? When you enter a commit for a range, the diff shows the changes between that commit and the working tree (with the working tree changes treated as new). Commented May 12, 2017 at 18:13
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Notably, you can now use
C-x lfrom themagit-difftransient state to enable the-Roption that reverses old and new, so that you get the diff in the order you want if you're pulling in changes selectively. Commented Aug 30, 2023 at 14:53
I am answering here because I could not find any existing answer on SO or StackExchange that solved this exact problem, but I just figured out one solution.
There are a few steps involved, but this is without custom elisp.
It depends on which buffer you're going to achieve this from, so I'll give an example of doing it from the magit-log or magit-refs buffer (i.e., instead of from a file buffer):
Optionally place point at the revision you want to diff your working tree against, then d (Diff), C-u (universal arg), w (Diff worktree) and enter a revision (default is revision at point). This will diff the entire tree and place you in a magit-diff buffer, so you can either (A) Navigate to the Magit section of the file you're interested in, or (B) Place point on one of the file paths in the first section and press e (Ediff dwim) to open an Ediff session against the file revision and the writable version of your working copy. This is the big differentiator you and I are after -- being able to pull hunks into the writable buffer visiting the working file (not being stymied by a readonly buffer populated with the blob from HEAD revision).
If you don't want to diff the entire tree, then you need to use -- (Limit to files) in the Magit Diff transient.
HTH!
