具体如下:

CMake Warning at cmake/OpenCVDetectCXXCompiler.cmake:182 (message):
  OpenCV does not recognize MSVC_VERSION "1940".  Cannot set OpenCV_RUNTIME
Call Stack (most recent call first):
  CMakeLists.txt:174 (include)

打开源码\opencv\sources\cmake找到OpenCVDetectCXXCompiler.cmake

修改vc17内容 

  elseif(MSVC_VERSION MATCHES "^193[0-9]$")
    set(OpenCV_RUNTIME vc17)


  elseif(MSVC_VERSION MATCHES "^19[34][0-9]$")
    set(OpenCV_RUNTIME vc17)