Merge pull request #4114 from alalek:ocl_generator_error_processing

cmake/OpenCVModule.cmake

@@ -662,7 +662,7 @@ macro(ocv_glob_module_sources)
     ocv_include_directories(${OPENCL_INCLUDE_DIRS})
     add_custom_command(
       OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${OCL_NAME}.cpp" "${CMAKE_CURRENT_BINARY_DIR}/${OCL_NAME}.hpp"
-      COMMAND ${CMAKE_COMMAND} -DMODULE_NAME="${name}" -DCL_DIR="${CMAKE_CURRENT_LIST_DIR}/src/opencl" -DOUTPUT="${CMAKE_CURRENT_BINARY_DIR}/${OCL_NAME}.cpp" -P "${OpenCV_SOURCE_DIR}/cmake/cl2cpp.cmake"
+      COMMAND ${CMAKE_COMMAND} "-DMODULE_NAME=${name}" "-DCL_DIR=${CMAKE_CURRENT_LIST_DIR}/src/opencl" "-DOUTPUT=${CMAKE_CURRENT_BINARY_DIR}/${OCL_NAME}.cpp" -P "${OpenCV_SOURCE_DIR}/cmake/cl2cpp.cmake"
       DEPENDS ${cl_kernels} "${OpenCV_SOURCE_DIR}/cmake/cl2cpp.cmake")
     ocv_source_group("Src\\opencl\\kernels" FILES ${cl_kernels})
     ocv_source_group("Src\\opencl\\kernels\\autogenerated" FILES "${CMAKE_CURRENT_BINARY_DIR}/${OCL_NAME}.cpp" "${CMAKE_CURRENT_BINARY_DIR}/${OCL_NAME}.hpp")

cmake/cl2cpp.cmake

+if (NOT EXISTS "${CL_DIR}")
+  message(FATAL_ERROR "Specified wrong OpenCL kernels directory: ${CL_DIR}")
+endif()
+
 file(GLOB cl_list "${CL_DIR}/*.cl" )
 list(SORT cl_list)
 
+if (NOT cl_list)
+  message(FATAL_ERROR "Can't find OpenCL kernels in directory: ${CL_DIR}")
+endif()
+
 string(REPLACE ".cpp" ".hpp" OUTPUT_HPP "${OUTPUT}")
 get_filename_component(OUTPUT_HPP_NAME "${OUTPUT_HPP}" NAME)