Out-params for script hooks via Lua can now be set

UE4SS/src/Mod/LuaMod.cpp

@@ -3398,7 +3398,15 @@ No overload found for function 'FPackageName:IsValidLongPackageName'.
                             if (auto it = LuaType::StaticState::m_property_value_pushers.find(param_type_comparison_index);
                                 it != LuaType::StaticState::m_property_value_pushers.end())
                             {
-                                auto data = param->ContainerPtrToValuePtr<void>(Stack.Locals());
+                                void* data{};
+                                if (param->HasAnyPropertyFlags(Unreal::EPropertyFlags::CPF_OutParm))
+                                {
+                                    data = Unreal::FindOutParamValueAddress(Stack, param);
+                                }
+                                else
+                                {
+                                    data = param->ContainerPtrToValuePtr<void>(Stack.Locals());
+                                }
                                 const LuaType::PusherParams pusher_param{
                                         .operation = LuaType::Operation::GetParam,
                                         .lua = lua,

assets/Changelog.md

@@ -23,6 +23,7 @@ Added an optional third parameter to `RegisterHook`
 If provided, it will act as a post callback hook where out-params can be modified  
 Note that for BP-only functions, both callbacks act as post callbacks
 
+Out-params for script hooks (`RegisterCustomEvent` or `RegisterHook` on a BP-only UFunction) can now be set by doing `Param:set(<new-value>)`
 
 ### C++ API
 Finalize C++ API. - LocalCC; Truman