What's the difference between “dead code” and “unreachable code”?

Question

I thought those terms where synonymous, but a note in MISRA regarding dead code indicates this to be wrong? What\'s the difference? Is one a subset of the other?

Answer 1

Dead Code

Code that performs functions that have no effect. Basically stuff that wouldn't make a difference if removed.

Unreachable Code

Code that due to other logic will never be executed. This is usually the sign of an error.