I'm using Git version 2.23. I have the `diff.renames` setting set to `copies`. My code base has a file named `JniPaymentManager.hpp` (and `cpp`) that had too much code in it, so I refactored this file by splitting out a significant portion of the code in it to another file, named `ZPayClient.hpp` (and `cpp`). When I diff the topic branch against the mainline, it shows it as a copy with a percentage: ``` $ git diff --name-status master...topic C055 Jni/JniPaymentManager.cpp ZPay/ZPayClient.cpp C070 Jni/JniPaymentManager.hpp ZPay/ZPayClient.hpp ``` Now my goal is to diff `ZPayClient.hpp` and see the changes to the moved-out portion of code as it relates to the original state of that code in `JniPaymentManager.hpp`. To do this, I tried this command: ``` $ git diff master...topic -- ZPay/ZPayClient.hpp ``` The unified diff header I got back is: ``` diff --git ZPay/ZPayClient.hpp ZPay/ZPayClient.hpp new file mode 100644 index 00000000..6ebc2a9a --- /dev/null +++ ZPay/ZPayClient.hpp ``` Hmm, it's treating it as a new file. Even though I have `diff.renames` set to `copies`? Even though `diff --name-status` acknowledges the relationship with the original file for the code on `master`? This is confusing... Out of curiosity, I thought I'd try this command: ``` git diff --follow master...topic -- ZPay/ZPayClient.hpp ``` And I get this unified diff header: ``` diff --git Jni/JniPaymentManager.hpp ZPay/ZPayClient.hpp similarity index 70% copy from Jni/JniPaymentManager.hpp copy to ZPay/ZPayClient.hpp index fc18e2d2..6ebc2a9a 100644 --- Jni/JniPaymentManager.hpp +++ ZPay/ZPayClient.hpp ``` Now this looks more like it. I can actually see a useful diff here, instead of everything looking like a new file. But there is a lot of confusion here: 1. `diff --follow` is not a documented[1] option. Why does it work? 2. `diff -M` doesn't actually work either. It should, though. In fact, I expected it to work as `--follow` does. But it doesn't. 3. The `diff.renames` config doesn't seem to be working here, when it should. Can someone explain the behavior I'm seeing? I really am confused about all this... [1]: https://git-scm.com/docs/git-diff
