Take cypclass locking mode into account for automatic lock acquisition

Cython/Compiler/CypclassTransforms.py

@@ -445,9 +445,15 @@ class CypclassLockTransform(Visitor.EnvTransform):
                 error(lock.pos, "A writelock is required, but a readlock is manually acquired")
             return obj
         except:
-            self.autolocks += 1
-            self.autowlocks += exclusive
-            return ExprNodes.CoerceToLockedNode(obj, self.current_env(), rlock_only = not exclusive)
+            lock_mode = obj.type.lock_mode
+            if lock_mode == "autolock":
+                self.autolocks += 1
+                self.autowlocks += exclusive
+                return ExprNodes.CoerceToLockedNode(obj, self.current_env(), rlock_only = not exclusive)
+            elif lock_mode == "checklock":
+                msg = "Reference '%s' is not correctly locked in this expression (%s lock required)"
+                error(obj.pos, msg % (obj.name, "write" if exclusive else "read"))
+            return obj
 
     def __call__(self, root):
         self.locked = {}