Calling Ediff which ignores whitespaces from VC Dir

["Sebastien Vauban" <sva-news-D0wtAvR13HarG/iDocfnWg@public.gmane.org>]

Hello,

I'm trying to call my version of `vc-diff' from VC Dir. It simply is a wrapper
above `vc-diff' where I enforce the fact that whitespaces must be ignored.

I thought this would make it:

--8<---------------cut here---------------start------------->8---
    ;; hide up-to-date and unregistered files
    (add-hook  'vc-dir-mode-hook
               (lambda ()
                 (define-key vc-dir-mode-map
                   (kbd "E") 'vc-ediff-ignore-whitespace)))

    (defun vc-ediff-ignore-whitespace ()
      "Ignore regions that differ in white space & line breaks only."
      (interactive)
      (let ((ediff-ignore-similar-regions t))
        (vc-ediff)))
--8<---------------cut here---------------end--------------->8---

but I always get the error:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (wrong-number-of-arguments (1 . 2) 0)
  vc-ediff()
  (let ((ediff-ignore-similar-regions t)) (vc-ediff))
  vc-ediff-ignore-whitespace(nil t)
  call-interactively(vc-ediff-ignore-whitespace nil nil)
--8<---------------cut here---------------end--------------->8---

which I don't really understand.

With no certainty, I've tried to copy the parameters of `vc-ediff':

--8<---------------cut here---------------start------------->8---
    (defun vc-ediff-ignore-whitespace (historic &optional not-urgent)
      "Ignore regions that differ in white space & line breaks only."
      (interactive (list current-prefix-arg t))
      (let ((ediff-ignore-similar-regions t))
        (vc-ediff historic not-urgent)))
--8<---------------cut here---------------end--------------->8---

then it worked further...

Though, I now have:

    call-interactively: Symbol's value as variable is void:
    ediff-ignore-similar-regions

when pressing `n' to go to the first difference region.

Any help?

Best regards,
  Seb

-- 
Sebastien Vauban