automatically enable whitespace mode in diff mode

Question

I have googled on this but can't find any elisp script for this. Sometimes i do a whitespace-cleanup then diff-buffer-with-file to see what whitespace-cleanup has done.

Answer 1

If you want whitespace-mode enabled for all diff-mode buffers:

(add-hook 'diff-mode-hook 
          '(lambda () 
            (whitespace-mode 1)))