simplify code to help MSVC 19.10 and lower

modules/dnn/src/cuda/grid_stride_range.hpp

@@ -12,25 +12,29 @@
 namespace cv { namespace dnn { namespace cuda4dnn { namespace csl { namespace device {
 
     namespace detail {
-        template <int>  __device__ auto getGridDim()->decltype(dim3::x);
-        template <> inline __device__ auto getGridDim<0>()->decltype(dim3::x) { return gridDim.x; }
-        template <> inline __device__ auto getGridDim<1>()->decltype(dim3::x) { return gridDim.y; }
-        template <> inline __device__ auto getGridDim<2>()->decltype(dim3::x) { return gridDim.z; }
-
-        template <int> __device__ auto getBlockDim()->decltype(dim3::x);
-        template <> inline __device__ auto getBlockDim<0>()->decltype(dim3::x) { return blockDim.x; }
-        template <> inline __device__ auto getBlockDim<1>()->decltype(dim3::x) { return blockDim.y; }
-        template <> inline __device__ auto getBlockDim<2>()->decltype(dim3::x) { return blockDim.z; }
-
-        template <int> __device__ auto getBlockIdx()->decltype(uint3::x);
-        template <> inline __device__ auto getBlockIdx<0>()->decltype(uint3::x) { return blockIdx.x; }
-        template <> inline __device__ auto getBlockIdx<1>()->decltype(uint3::x) { return blockIdx.y; }
-        template <> inline __device__ auto getBlockIdx<2>()->decltype(uint3::x) { return blockIdx.z; }
-
-        template <int> __device__ auto getThreadIdx()->decltype(uint3::x);
-        template <> inline __device__ auto getThreadIdx<0>()->decltype(uint3::x) { return threadIdx.x; }
-        template <> inline __device__ auto getThreadIdx<1>()->decltype(uint3::x) { return threadIdx.y; }
-        template <> inline __device__ auto getThreadIdx<2>()->decltype(uint3::x) { return threadIdx.z; }
+        using dim3_member_type = decltype(dim3::x);
+
+        template <int>  __device__ dim3_member_type getGridDim();
+        template <> inline __device__ dim3_member_type getGridDim<0>() { return gridDim.x; }
+        template <> inline __device__ dim3_member_type getGridDim<1>() { return gridDim.y; }
+        template <> inline __device__ dim3_member_type getGridDim<2>() { return gridDim.z; }
+
+        template <int> __device__ dim3_member_type getBlockDim();
+        template <> inline __device__ dim3_member_type getBlockDim<0>() { return blockDim.x; }
+        template <> inline __device__ dim3_member_type getBlockDim<1>() { return blockDim.y; }
+        template <> inline __device__ dim3_member_type getBlockDim<2>() { return blockDim.z; }
+
+        using uint3_member_type = decltype(uint3::x);
+
+        template <int> __device__ uint3_member_type getBlockIdx();
+        template <> inline __device__ uint3_member_type getBlockIdx<0>() { return blockIdx.x; }
+        template <> inline __device__ uint3_member_type getBlockIdx<1>() { return blockIdx.y; }
+        template <> inline __device__ uint3_member_type getBlockIdx<2>() { return blockIdx.z; }
+
+        template <int> __device__ uint3_member_type getThreadIdx();
+        template <> inline __device__ uint3_member_type getThreadIdx<0>() { return threadIdx.x; }
+        template <> inline __device__ uint3_member_type getThreadIdx<1>() { return threadIdx.y; }
+        template <> inline __device__ uint3_member_type getThreadIdx<2>() { return threadIdx.z; }
     }
 
     template <int dim, class index_type = device::index_type, class size_type = device::size_type>

modules/dnn/src/cuda4dnn/csl/cudnn/cudnn.hpp

@@ -37,9 +37,10 @@ namespace cv { namespace dnn { namespace cuda4dnn { namespace csl { namespace cu
         }
 
         /** get_data_type<T> returns the equivalent cudnn enumeration constant for type T */
-        template <class> auto get_data_type()->decltype(CUDNN_DATA_FLOAT);
-        template <> inline auto get_data_type<half>()->decltype(CUDNN_DATA_HALF) { return CUDNN_DATA_HALF; }
-        template <> inline auto get_data_type<float>()->decltype(CUDNN_DATA_FLOAT) { return CUDNN_DATA_FLOAT; }
+        using cudnn_data_enum_type = decltype(CUDNN_DATA_FLOAT);
+        template <class> cudnn_data_enum_type get_data_type();
+        template <> inline cudnn_data_enum_type get_data_type<half>() { return CUDNN_DATA_HALF; }
+        template <> inline cudnn_data_enum_type get_data_type<float>() { return CUDNN_DATA_FLOAT; }
     }
 
     /** @brief noncopyable cuDNN smart handle