UE 5.5 Upgrade Blocked

[Tezenari]

Description

Upgrading the UDCore plugin to support Unreal Engine 5.5 is currently blocked due to an engine change.

In the UEditorActorSubsystem.h file, UNREALED_API was removed from the Initialize function, causing the following LNK2001 error --

Module.UDCoreEditor.cpp.obj: Error LNK2001 : unresolved external symbol "public: virtual void __cdecl UEditorActorSubsystem::Initialize(class FSubsystemCollectionBase &)" (?Initialize@UEditorActorSubsystem@@UEAAXAEAVFSubsystemCollectionBase@@@Z)

While Initialize isn't being used in the conflicting UDCoreEditorActorSubsystem header file, the linker error persists.

I am currently looking into addressing this issue.

Additional Information

Essentially, the missing UNREALED_API macro is causing the linker error.

Pre Unreal Engine 5.5

UNREALED_API virtual void Initialize(FSubsystemCollectionBase& Collection) override;

Unreal Engine 5.5

virtual void Initialize(FSubsystemCollectionBase& Collection) override;

Temporary Solution

If you are not using the UDCoreEditorActorSubsystem, you may comment out the code in UDCoreEditorActorSubsystem.h and UDCoreEditorActorSubsystem.cpp to bypass this linker error.

[Tezenari]

While there's most likely a new dependency/include that is required for the change, I have not been able to hunt it down.

Regardless, I've submitted a pull request to revert the change engine side.

[Tezenari]

It appears that my engine pull request addressing this regression was accepted and will be included in the next Unreal Engine version. However, it unfortunately didn’t make it into a 5.5 hotfix.

To work around this, I added a 5.5-specific conditional that ‘hides’ the parent UEditorActorSubsystem::Initialize and applied the fix directly in UDEditorActorSubsystem.