Thanks for report! I was able to reproduce this in 4.8.3, 4.9.0, and our internal build, so I’ve entered a bug report for issue (UE-21008). I’ll post here if I see any update on it. Thanks again!
As a note for anyone else out there running into this: this DOES cause a compiler error, so keep an eye out for that.
You can find this report on public bug database here. At moment, this is marked as “To do” so it will be looked at but I can’t give any kind of estimate as to when it will be fixed.