'git diff': Show only diff for files that exist in both commits

Question

Is there a way to use git diff to get a diff between two commits, but only show the diff for the files that exist in both commits?

I have a branch I created a couple of weeks ago, and our main code has diverged quite a bit from it by now. As a result, if I do a diff between my current HEAD and the tip of the old branch, I get dozens of changed files, but it's mostly just noise.

I really want to see a diff that shows only the files that exist in both branches. I know one way to do this would be to cherry-pick the other branch's commits on top of the current HEAD, but is there a way to do it just using git diff?

Answer 1

The following may do what you want:

git diff --diff-filter=M commitA commitB 

The M option to --diff-filter says only to include files that appear to be modified between the two commits - ones that only exist in one branch or the other would be selected with A ("added") or D ("deleted").

You can see which files would be selected with these letter codes by doing:

git diff --name-status commitA commitB 

... and there's more information about all of that in the git diff documentation.