GIT/DIFF - Reverse patch between a moved local file and an old commit

Question

There was a commit for a particular file, at some point that needs to be reversed

I want to create a revert patch between that old commit with hash #A1B2C3D4:

folderA/file.c

...and the file in my working folder (on main branch):

folderB/folderC/file.c

The difficulty here, for me is that the file has been moved to another directory structure

how does one use git/diff/gittools/bc to generate such a reverse patch to a file that was moved?

I checked the doc, but git revert command does not seem to do what I want

thanks for your help

[edit]

I tried

git diff A1B2C3D4 HEAD -- folderA/file.c folderB/folderC/file.c

it returned

Similarity index 100%
rename from folderA/file.c
rename from folderB/folderC/file.c

Answer 1

You could checkout A1B2C3D4, rename the file there to the name that you have now. Then you can compare the 2 commits that you care about to generate the patch

git checkout A1B2C3D4
git mv some-file some-file-new-path
git commit -m "Renamed file"
git diff the-other-commit -- some-file-new-path > some-patch-revert.patch
git diff HEAD the-other-commit -- some-file-new-path > some-patch.patch

Use the patch that best suits your needs.

Answer 2

If there is sufficient common text in the old version and the new version, Git should be able to determine that the file was renamed. Then you also receive a patch text the shows the changes with this command:

git diff old-commit HEAD -- folderA/file.c  folderB/folderC/file.c

The command instructs git diff to investigate the two files. Of course, one path is not present in HEAD the other is not present it old-commit. For this reason, add -- to the command to tell git diff: no, really, I mean that the following two arguments are file paths (more correctly: pathspec).