Appreciated. Thanks.

(Using opencv 4 and macOS)

I manually made the changes you have done @joanpepcompany
I'm getting the error - fatal error: 'cv.h' file not found"cv.

Any help ?

Hello,
I have modified the code for OpenCV3, I think the problem is because OpenCV4 does no more install the deprecated (1.0) c-api header. [ https://answers.opencv.org/question/225224/opencvcvh-not-found/ ].
The previous website presents a solution to your problem but I can't test it because I only have OpenCV 3. This solution is to change the headers from #include <opencv/cv.h> to #include <opencv2/opencv.hpp>. I have seen that the headers to change appears in: src/IO.h, src/main.cpp, src/PartiallyRecoverConnectivity.h, src/MatOperation.h, src/LineMatching.h.
If it does not work I strongly recommend that you change to the OpenCV3.
Regards,
Joan Pep

There are plenty more issues after that, especially with the C API identifiers (eg. error: use of undeclared identifier 'CV_REDUCE_SUM'; did you mean 'REDUCE_SUM'). Will get a system with OpenCV3. Also CV4 requires c++ 11 standard. Just keeping this here for any other poor soul to save some time.