A really annoying new “feature” of blueprint compile checker: it will throw flags on basically ANYTHING you do involving Interface Messages.
As an example, I have an interface implemented on many actors. I use this so that I can communicate messages to them just by getting an actor reference (say, on an overlap event; this way, if a weapon overlaps an enemy, I can tell whatever actor class it happens to BE how to react). So, I call interface on Actor reference. This actually WORKS in-game… but on attempting to compile, UE4 warns me that it will “always fail” because CLASS OF “ACTOR” doesn’t implement interface! That seems like it entirely negates POINT of interface messages, which is to enable inter-actor communication when specific class of referenced object cannot be known.
I want to reiterate, functionality in-game hasn’t changed at all. UE4 just now feels like alerting me that it won’t work, even though it will.
I also get warning flags for component overlap messages, letting me know that I won’t get any data from my Sweep Result pin (which never yielded anything anyway), even if it isn’t connected to anything.