I recently got promoted to be the manager of a guy who has literally been my best friend since we were 10. There will come a time when you will know something

I recently got promoted to be the manager of a guy who has literally been my best friend since we were 10. There will come a time when you will know something he can't know, such as layoffs are coming. Or maybe he deserves that promotion/raise but you can't give it to him because everyone knows you're friends and you open yourself to accusations of favoritism (or worse). If you really want to square this circle the only way to to get yourself moved to a different reporting line.