(defun make-obsolete (obsolete-name current-name &optional when)
"Make the byte-compiler warn that OBSOLETE-NAME is obsolete.
The warning will say that CURRENT-NAME should be used instead.
-If CURRENT-NAME is a string, that is the `use instead' message.
+If CURRENT-NAME is a string, that is the `use instead' message
+\(it should end with a period, and not start with a capital).
If provided, WHEN should be a string indicating when the function
was first made obsolete, for example a date or a release number."
(interactive "aMake function obsolete: \nxObsoletion replacement: ")