Detect mistaken Java enums / symbols in case form

[pbwolf]

Clojure's case form does not evaluate test constants. This trips folks up (CLJ-1367 and CLJ-1368) who expected case to evaluate symbols that indicate constants whose value the compiler knows. Eastwood could help by pointing out case test constants which, if evaluated, would also yield constants, the latter being perhaps what the programmer had intended for case to consider. For example, the following program ought to print 42.

(defn -main
  "I don't do a whole lot ... yet."
  [& args]
  (println
   (let [a OutputKeys/DOCTYPE_SYSTEM]
     (case a
       OutputKeys/DOCTYPE_PUBLIC :oops
       OutputKeys/DOCTYPE_SYSTEM 42
       ;;else
       :oops))))