The byte-compiler currently optimises various constant expressions, for
example:

  (byte-compile '(string-equal "" ""))
  ;; => t

IWBNI this was also done for proper-list-p:

  (byte-compile '(proper-list-p '(0)))
  ;; => (byte-code "\300\301!\207" [proper-list-p (0)] 2)

Is the following kosher?