Due to sample issues, Future had to settle for releasing “Rock Star” as a free leak. Outside of a Nicki feature, nothing much was lost for this not being included on Future’s Honest. And considering the sample source, I can understand why George Michael didn’t care for Future’s dying cat vocals butchering a classic 80s ballad.
Source: Rap Boost
“ROCK STAR”
Beats, Boxing and Mayhem 
Nice.