diff a file that has been renamed?

[BatmanAoD]

How can I make jj diff show just the content changes in a file that has been renamed? jj diff <newname> shows that the entire contents are new.

[ilyagr]

Currently, the easiest way I can think of is cp <newname> <oldname>; jj diff <oldname>.

We (@fowles especially) are working on copy tracking, see e.g. #3386. It's possible that some version of it will be usable soon, diff specifically is probably one of the first copy tracking features that's going to happen.

Update: Just to be clear, there are no promises. I pinged Matt in the sense of "hey, your work is appreciated", not in the sense of "you are now responsible for doing ABC on XYZ schedule".

[fowles]

the last PR in the series is #4279 after that, it is just waiting for a new release. So I feel fairly confident in saying it will be ready in time for the next release.

If you use an external diff tool, it must be run in file-by-file mode.

[BatmanAoD]

Now that copy-tracking has been released (🎉), is there a way to configure conflict-resolution such that, when a rename happens on one or both sides of a diff, the last version of the pre-rename file is used as the $base?

I have a branch where I renamed a file, and that file changed in trunk() while I was working on the branch. I thought I could potentially make the merge easier by making a separate MR that renamed the file to match the name in my branch (so this was the "both sides of a diff" case). But conflict resolution, regardless of whether I used new or rebase, treated both sides as fully unique, with no shared content in the "base" revision.

What I ended up doing was:

• I duplicated the trunk() commit that my branch was based on (i.e. the shared ancestor commit, in which the file had the old name).
• I edited the duplicate commit by copying the file to the new name.
• I rebased my branch onto the newly edited commit, then resolved the resulting conflict in favor of my branch (i.e. I accepted all changes from my branch and ignored the "left" side of the conflict).
• I then rebased my branch again (excluding the duplicate commit), this time onto trunk(). This gave ma a proper diff to resolve.

[yuja]

is there a way to configure conflict-resolution such that, when a rename happens on one or both sides of a diff, the last version of the pre-rename file is used as the $base?

No, rename tracking isn't add to merge/rebase logic yet.