Fixed memory issue with python proxy notifications. #2318

The memory of the returned parameter was being released before it was finally read and set to the final behaviour parameter in BehaviorEBusHandler::CallResult.

Making the result parameter a member of the class so its memory in still present when read in CallResult.

Signed-off-by: moraaar moraaar@amazon.com

Gems/EditorPythonBindings/Code/Source/PythonProxyBus.cpp

@@ -264,7 +264,7 @@ namespace EditorPythonBindings
                 reinterpret_cast<PythonProxyNotificationHandler*>(userData)->OnEventGenericHook(eventName, eventIndex, result, numParameters, parameters);
             }
 
-            void OnEventGenericHook(const char* eventName, [[maybe_unused]] int eventIndex, [[maybe_unused]] AZ::BehaviorValueParameter* result, int numParameters, AZ::BehaviorValueParameter* parameters)
+            void OnEventGenericHook(const char* eventName, [[maybe_unused]] int eventIndex, AZ::BehaviorValueParameter* result, int numParameters, AZ::BehaviorValueParameter* parameters)
             {
                 // find the callback for the event
                 const auto& callbackEntry = m_callbackMap.find(eventName);
@@ -299,12 +299,17 @@ namespace EditorPythonBindings
                         // reset/prepare the stack allocator
                         m_stackVariableAllocator = {};
 
-                        AZ::BehaviorValueParameter coverted;
+                        // Reset the result parameter
+                        m_resultParam = {};
+
                         const AZ::u32 traits = result->m_traits;
-                        if (Convert::PythonToBehaviorValueParameter(*result, pyResult, coverted, m_stackVariableAllocator))
+                        if (Convert::PythonToBehaviorValueParameter(*result, pyResult, m_resultParam, m_stackVariableAllocator))
                         {
-                            result->Set(coverted);
-                            result->m_value = coverted.GetValueAddress();
+                            // Setting result parameter into the output parameter will not fix its pointers
+                            // to use output parameter's internal memory, because of this, result parameter
+                            // needs to be a member so its memory is still valid when accessed in BehaviorEBusHandler::CallResult.
+                            result->Set(m_resultParam);
+                            result->m_value = m_resultParam.GetValueAddress();
                             if ((traits & AZ::BehaviorParameter::TR_POINTER) == AZ::BehaviorParameter::TR_POINTER)
                             {
                                 result->m_value = &result->m_value;
@@ -323,6 +328,7 @@ namespace EditorPythonBindings
             AZ::BehaviorEBusHandler* m_handler = nullptr;
             AZStd::unordered_map<AZStd::string, pybind11::function> m_callbackMap;
             Convert::StackVariableAllocator m_stackVariableAllocator;
+            AZ::BehaviorValueParameter m_resultParam;
         };
     }