Yeah… it’s behavior that’s controlled by GNU make. We haven’t found a better solution across platforms and we don’t have the expertise to build out a separate make process for Windows, so for the foreseeable future, we’re reliant on make’s behavior for Windows.
It’s amazing that it can recognize backslashes for the target once it’s built, but not for compiling. I have no idea why that is.
Thanks for posting back after figuring this out. We probably only need one user who knows the right approach on Windows and the world would be a better place.