Fixing some compiler warnings

modules/optflow/include/opencv2/optflow/pcaflow.hpp

@@ -116,6 +116,8 @@ private:
   void getSystem( OutputArray A1Out, OutputArray A2Out, OutputArray b1Out, OutputArray b2Out,
                   const std::vector<Point2f> &features, const std::vector<Point2f> &predictedFeatures,
                   const Size size );
+
+  OpticalFlowPCAFlow& operator=( const OpticalFlowPCAFlow& ); // make it non-assignable
 };
 
 CV_EXPORTS_W Ptr<DenseOpticalFlow> createOptFlow_PCAFlow();

modules/optflow/src/pcaflow.cpp

@@ -43,6 +43,17 @@
 #include "opencv2/ximgproc/edge_filter.hpp"
 #include "precomp.hpp"
 
+/* Disable "from double to float" and "from size_t to int" warnings.
+ * Fixing these would make the code look ugly by introducing explicit cast all around.
+ * Here these warning are pointless anyway.
+ */
+#ifdef _MSC_VER
+#pragma warning( disable : 4305 4244 4267 4838 )
+#endif
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wshorten-64-to-32"
+#endif
+
 namespace cv
 {
 namespace optflow