First compile this:

    enum Color {
        red, green
    }

    class Main {
        static int f(Color c) {
            switch(c) {
            case green:
                return 2;
            case red:
                return 1;
            default:
                return 0;
            }
        }

        public static void main(String[] args) {
            f(Color.red);
        }
    }

and then this:

    enum Color {
        red
    }

and then run Main. The binary compatibility rules for enums require
the program to execute to completion with no exceptions, but the current
implementation using chained if statements does not do that.