vs2015 cmake编译opencv3.1+opencv_contrib报错

Question

在OPENCV_EXTRA_MODULES_PATH，添加opencv_contrib目录后报错，求问是什么问题啊？
CMake Error at /Users/Documents/opencv/source/opencv-3.2.0/cmake/OpenCVUtils.cmake:1045 (file):
file DOWNLOAD cannot open file for write.
Call Stack (most recent call first):
/Users/Documents/opencv/source/opencv_contrib-master/modules/dnn/cmake/OpenCVFindLibProtobuf.cmake:32 (ocv_download)
/Users/Documents/opencv/source/opencv_contrib-master/modules/dnn/CMakeLists.txt:5 (include)

CMake Error at /Users/Documents/opencv/source/opencv-3.2.0/cmake/OpenCVUtils.cmake:1049 (message):
Failed to download . Status=
Call Stack (most recent call first):
/Users/Documents/opencv/source/opencv_contrib-master/modules/dnn/cmake/OpenCVFindLibProtobuf.cmake:32 (ocv_download)
/Users/Documents/opencv/source/opencv_contrib-master/modules/dnn/CMakeLists.txt:5 (include)

Answer 1

http://blog.csdn.net/yomo127/article/details/50474955