Possible fix for [#36086] Activating the opencl option in the compositor causes blender crash

* Now OCL_init() returns error messages if the OpenCL library cannot be loaded.

intern/opencl/OCL_opencl.h

@@ -28,7 +28,7 @@ extern "C" {
 #endif
 
 #include "intern/clew.h"
-void OCL_init(void);
+int OCL_init(void);
 
 #ifdef __cplusplus
 }

intern/opencl/intern/OCL_opencl.c

@@ -22,7 +22,7 @@
 
 #include "OCL_opencl.h"
 
-void OCL_init(void)
+int OCL_init(void)
 {
 #ifdef _WIN32
 	const char *path = "OpenCL.dll";
@@ -32,6 +32,6 @@ void OCL_init(void)
 	const char *path = "libOpenCL.so";
 #endif
 
-	clewInit(path);
+	return (clewInit(path) == CLEW_SUCCESS);
 }
 

intern/opencl/intern/clew.c

@@ -227,6 +227,11 @@ int clewInit(const char* path)
     __oclEnqueueWaitForEvents          = (PFNCLENQUEUEWAITFOREVENTS        )CLCC_DYNLIB_IMPORT(module, "clEnqueueWaitForEvents");
     __oclEnqueueBarrier                = (PFNCLENQUEUEBARRIER              )CLCC_DYNLIB_IMPORT(module, "clEnqueueBarrier");
     __oclGetExtensionFunctionAddress   = (PFNCLGETEXTENSIONFUNCTIONADDRESS )CLCC_DYNLIB_IMPORT(module, "clGetExtensionFunctionAddress");
+	
+	if(__oclGetPlatformIDs == NULL) return CLEW_ERROR_OPEN_FAILED;
+	if(__oclGetPlatformInfo == NULL) return CLEW_ERROR_OPEN_FAILED;
+	if(__oclGetDeviceIDs == NULL) return CLEW_ERROR_OPEN_FAILED;
+	if(__oclGetDeviceInfo == NULL) return CLEW_ERROR_OPEN_FAILED;
 
     return CLEW_SUCCESS;
 }

source/blender/compositor/intern/COM_WorkScheduler.cpp

@@ -304,7 +304,8 @@ void WorkScheduler::initialize(bool use_opencl)
 		g_context = NULL;
 		g_program = NULL;
 
-		OCL_init(); /* this will check and skip if already initialized */
+		if(!OCL_init()) /* this will check for errors and skip if already initialized */
+			return;
 
 		if (clCreateContextFromType) {
 			cl_uint numberOfPlatforms = 0;