Custom event with reference input warning

Hi, i made a custom event in my AIController with a reference input that is called every time the pawn start overlap with a custom TriggerBox; from the pawn i call the custom event in the controller to let it decide what to do, but the custom event has a warning “Warning No value will be returned by reference.”.

What does it mean?

I tried it out wit a simple printf and it work correctly.
Any ideas?

Have the same issue on 4.11 and 4.12 preview 5. It’s working fine and this warning is really annoying.

Still a bit of an annoying problem in 4.18.

Would be good if this could be improved. Preferably just don’t show the warning for by-ref vars on custom events? Or alternately, allow us to manually right click on an event and say “Ignore compile warnings” (for this node)

Did you check “Pass-by-reference” when you created your TriggerBox input? Unchecking this fixed it for me, however you lose the fuctionality of it. You can just manually do the pass by reference by outputting TriggerBox and setting it from the blueprint that called the event.

Edit: I didn’t notice this at first, but the warning doesn’t change any funcitonality as it still works. I’ll just leave this up since personally warning messages bug the hell out of me.

Still happening on 4.26, with this declaration:

UFUNCTION(BlueprintNativeEvent, BlueprintCallable)
void OnDeath(UPARAM(ref)FVector& DamageDirection);