Reserved word "bit" as signal name

"bit" is a predefined type in the package standard. I'd be very surprised if that code compiled; if it does I would expect that you'd encounter weird problems down the road. Keywords are exactly that - if you start using them as signal / variable names then the compiler cannot understand what you're trying to tell it.

Even if that code does compile it's asking for trouble - I would advise that you change it. Besides, "bit" isn't very descriptive and doesn't help another programmer understand what your code is doing.

Hope this helps.