datastart must be non-const in CUDA.

modules/core/include/opencv2/core/cuda.hpp

@@ -261,7 +261,7 @@ public:
     int* refcount;
 
     //! helper fields used in locateROI and adjustROI
-    const uchar* datastart;
+    uchar* datastart;
     const uchar* dataend;
 
     //! allocator
@@ -349,7 +349,7 @@ public:
     uchar* data;
     int* refcount;
 
-    const uchar* datastart;
+    uchar* datastart;
     const uchar* dataend;
 
     AllocType alloc_type;

modules/core/src/cuda/gpu_mat.cu

@@ -160,7 +160,7 @@ void cv::cuda::GpuMat::release()
     if (refcount && CV_XADD(refcount, -1) == 1)
         allocator->free(this);
 
-    data = datastart = dataend = 0;
+    dataend = data = datastart = 0;
     step = rows = cols = 0;
     refcount = 0;
 }

modules/core/src/cuda_gpu_mat.cpp

@@ -49,7 +49,7 @@ using namespace cv::cuda;
 cv::cuda::GpuMat::GpuMat(int rows_, int cols_, int type_, void* data_, size_t step_) :
     flags(Mat::MAGIC_VAL + (type_ & Mat::TYPE_MASK)), rows(rows_), cols(cols_),
     step(step_), data((uchar*)data_), refcount(0),
-    datastart((uchar*)data_), dataend((uchar*)data_),
+    datastart((uchar*)data_), dataend((const uchar*)data_),
     allocator(defaultAllocator())
 {
     size_t minstep = cols * elemSize();
@@ -75,7 +75,7 @@ cv::cuda::GpuMat::GpuMat(int rows_, int cols_, int type_, void* data_, size_t st
 cv::cuda::GpuMat::GpuMat(Size size_, int type_, void* data_, size_t step_) :
     flags(Mat::MAGIC_VAL + (type_ & Mat::TYPE_MASK)), rows(size_.height), cols(size_.width),
     step(step_), data((uchar*)data_), refcount(0),
-    datastart((uchar*)data_), dataend((uchar*)data_),
+    datastart((uchar*)data_), dataend((const uchar*)data_),
     allocator(defaultAllocator())
 {
     size_t minstep = cols * elemSize();

modules/core/src/cuda_host_mem.cpp

@@ -175,7 +175,7 @@ void cv::cuda::CudaMem::release()
         fastFree(refcount);
     }
 
-    data = datastart = dataend = 0;
+    dataend = data = datastart = 0;
     step = rows = cols = 0;
     refcount = 0;
 #endif