opencv mouse callback with c++11 lambda and capture

opencv-mouse-callback-lambda.cpp

/* 
if you don't need to do any captures you can just do

cv::setMouseCallback("win", [] (int event, int x, int y, int flags, void*userdata) {
  std::cout << "mouse action!" << std::endl;
});

but if you need to do any captures, then you'll need to do this crap.
If you know of a better way then fork away...
*/

using MouseAction = std::function<void(int, int, int, int)>;

void setMouseAction(const std::string& winName, const MouseAction& action)
{
  cv::setMouseCallback(winName,
                       [] (int event, int x, int y, int flags, void* userdata) {
    (*(MouseAction*)userdata)(event, x, y, flags);
  }, (void*)&action);
}

void userCode()
{
  cv::namedWindow("win");
  
  setMouseAction("win", [&] (int event, int x, int y, int flags) {
    std::cout << "mouse action!" << std::endl;
  });
}

this seems to crash in unpredictable ways...