flet and byte-compiled primitives

gistfile1.el

;; discussed this with jlf and turbofail in #emacs

;; say we want a function face-at-pos, and we attempt to do
;; it by fletting `point' and using `face-at-point'

(defun face-at-pos (pos)
   "return the face at position p using face-at-point"
   (flet ((point () pos))
     (face-at-point))) ;; face-at-point uses `point' internally

;; that won't work if face-at-point is byte-compiled since `point' is
;; a bytecode primitive and the interpreter will bypass the symbol
;; lookup (so no flet!)
;; One can see the byte-opcode flag set in (symbol-plist 'point)