*Backtrace*

;; Running on GNU Emacs 26.0.90
Debugger entered--Lisp error: (wrong-type-argument tramp-file-name nil)
  signal(wrong-type-argument (tramp-file-name nil))
    debugger-may-continue = t
    inhibit-redisplay = nil
    inhibit-debugger = t
    inhibit-changing-match-data = nil
  (or (progn (and (memq (car-safe nil) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name nil)))
    [no locals]
  (progn (or (progn (and (memq (car-safe nil) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name nil))) (nth 2 nil))
    [no locals]
  (tramp-make-tramp-file-name "sudo" (progn (or (progn (and (memq (car-safe nil) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name nil))) (nth 2 nil)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 4 vec)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 6 vec)) (format "ssh:%s@%s|" (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 2 vec)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 4 vec))))
    [no locals]
  (let ((vec (tramp-dissect-file-name tempfile))) (tramp-make-tramp-file-name "sudo" (progn (or (progn (and (memq (car-safe nil) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name nil))) (nth 2 nil)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 4 vec)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 6 vec)) (format "ssh:%s@%s|" (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 2 vec)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 4 vec)))))
    vec = (tramp-file-name "ssh" "superbil" nil "pi" nil "/etc/." nil)
  (if (file-remote-p tempfile) (let ((vec (tramp-dissect-file-name tempfile))) (tramp-make-tramp-file-name "sudo" (progn (or (progn (and (memq (car-safe nil) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name nil))) (nth 2 nil)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 4 vec)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 6 vec)) (format "ssh:%s@%s|" (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 2 vec)) (progn (or (progn (and (memq (car-safe vec) cl-struct-tramp-file-name-tags) t)) (signal 'wrong-type-argument (list 'tramp-file-name vec))) (nth 4 vec))))) (concat "/sudo:root@localhost:" tempfile))
    [no locals]
  prepare-tramp-sudo-string("/ssh:superbil@pi:/etc/.")
    tempfile = "/ssh:superbil@pi:/etc/."
  (find-alternate-file (prepare-tramp-sudo-string my-file-name))
    [no locals]
  (progn (setq my-file-name (dired-get-file-for-visit)) (find-alternate-file (prepare-tramp-sudo-string my-file-name)))
    [no locals]
  (if (equal major-mode 'dired-mode) (progn (setq my-file-name (dired-get-file-for-visit)) (find-alternate-file (prepare-tramp-sudo-string my-file-name))) (setq my-file-name (buffer-file-name) position (point)) (find-alternate-file (prepare-tramp-sudo-string my-file-name)) (goto-char position))
    [no locals]
  (let ((my-file-name) (position)) (if (equal major-mode 'dired-mode) (progn (setq my-file-name (dired-get-file-for-visit)) (find-alternate-file (prepare-tramp-sudo-string my-file-name))) (setq my-file-name (buffer-file-name) position (point)) (find-alternate-file (prepare-tramp-sudo-string my-file-name)) (goto-char position)))
    my-file-name = "/ssh:superbil@pi:/etc/."
    position = nil
  sudo-edit-current-file()
    [no locals]
  funcall-interactively(sudo-edit-current-file)
  call-interactively(sudo-edit-current-file nil nil)
  command-execute(sudo-edit-current-file)

sudo.el

  (defun prepare-tramp-sudo-string (tempfile)
    (if (file-remote-p tempfile)
        (let ((vec (tramp-dissect-file-name tempfile)))

          (tramp-make-tramp-file-name
           "sudo"
           (tramp-file-name-user nil)
           (tramp-file-name-host vec)
           (tramp-file-name-localname vec)
           (format "ssh:%s@%s|"
                   (tramp-file-name-user vec)
                   (tramp-file-name-host vec))))
      (concat "/sudo:root@localhost:" tempfile)))

  (defun sudo-edit-current-file ()
    (interactive)
    (let ((my-file-name)     ; fill this with the file to open
          (position))        ; if the file is already open save position
      (if (equal major-mode 'dired-mode) ; test if we are in dired-mode
          (progn
            (setq my-file-name (dired-get-file-for-visit))
            (find-alternate-file (prepare-tramp-sudo-string my-file-name)))
        (setq my-file-name (buffer-file-name) ; hopefully anything else is an already opened file
              position (point))
        (find-alternate-file (prepare-tramp-sudo-string my-file-name))
        (goto-char position))))

好像這樣也行…

(defun prepare-tramp-sudo-string (tempfile)
  (if (version< tramp-version "2.3")
      (if (file-remote-p tempfile)
          (let ((vec (tramp-dissect-file-name tempfile)))
            (tramp-make-tramp-file-name
             "sudo"
             (tramp-file-name-user nil)
             (tramp-file-name-host vec)
             (tramp-file-name-localname vec)
             (format "ssh:%s@%s|"
                     (tramp-file-name-user vec)
                     (tramp-file-name-host vec))))
        (concat "/sudo:root@localhost:" tempfile))
    ;; For new version tramp
    (if (file-remote-p tempfile)
        (let ((vec (tramp-dissect-file-name tempfile)))
          (tramp-make-tramp-file-name
           "sudo"
           nil
           (tramp-file-name-domain vec)
           (tramp-file-name-host vec)
           (tramp-file-name-port vec)
           (tramp-file-name-localname vec)))
      (concat "/sudo:localhost:" tempfile))))