Can I move lines when committing parts of a hunk in magit?

Question

I prefer to have small and focused commits but don't always code that way. I've got a code section to the effect of

if abc:
    def
etc

I edited def and etc, and the hunk in magit shows both as removed and then the edited parts as inserted.

@@ -1,3 +1,3 @@
 if abc:
-    def
-etc
+    ghi
+etc...

I want to make one commit with just the def edit, but as it is it removes def and inserts the new version after etc when I select those lines manually.

How can I create one commit that results in code

if abc:
    ghi
etc...

instead of

if abc:
etc...
    ghi

Would committing the remove of def and ammending with the add of ghi be the only way to do it?

Answer 1

It's possible in Magit, though how to do so isn't obvious or straightforward. Call magit-ediff-dwim (e) on the unstaged hunk. This will bring up three windows. One of them (B, at least for me) is labeled as the index. Switch to the index window and change the content to match what you want to stage. For example, change it to

if abc:
    ghi
etc

to stage just the "def" -> "ghi" change.

Then switch back to the ediff control panel buffer and quit the ediff session with q, confirming the update the index when you are asked.

After you commit those staged changes, your unstaged changes will be

 if abc:
     ghi
-etc
+etc...

which you can stage and commit as usual.

---

Note that there's been some previous discussion related to this on the Magit issue tracker (gh-2165, gh-2173, gh-2718). There's also an open feature request to add support for editing diffs (gh-2938), which would provide an alternative way to achieve what you're after.