Errors on CCL when a structure slot name has a macro function

[guicho271828]

(defstruct slice begin end step)
...
(match x
  ((slice begin end step)
    ...))

This will try to funcall (symbol-function step), but since step is a macro function "an object of implementation-dependent nature and identity is returned". http://clhs.lisp.se/Body/f_symb_1.htm