https://forum.dlang.org/post/zpqpwsmzledcvvpynnfo@forum.dlang.org

It is a compile-time error if a statement cannot be executed because it is unreachable. This means that the control flow of your program can't get to that statement, but you assume that they would be. The compiler analyzes the flow, and reports these statements to you as error messages. It is a reliable indicators of logical error in your program.

When the compiler reports an unreachable statement , it typically points you to the statement. When that happens, you can follow the flow of control from top to bottom to discover why the statement can never be reached. There are quite strict rules when statements are reachable in java. These rules are design to be easily evaluated and not to be 100% accurate. It should prevent basic programming errors.

http://net-informations.com/java/err/unreachable.htm