I'd like to enable whitespace-mode from a .dir-locals.el file such that when I open a file managed by cc-mode, I will see trailing spaces highlighted with the whitespace face.

I think I'm close. This is what I have in my .dir-locals.el, but its not quite enough.

((cc-mode . ((whitespace-style . (face trailing))            
             (whitespace-active-style . (face trailing))))

But if I M-xwhitespace-toggle-options and choose f, then the trailing whitespace is highlighted.

1 Answer 1


Use the special "variable" eval as described in Specifying File Variables.

This .dir-locals.el code enables whitespace-mode for me:

  (eval . (whitespace-mode))))

(I use Emacs 24.4.1.)

  • Except I would strongly recommend using the more readable (albeit entirely equivalent) dotted pair syntax: (eval . (whitespace-mode))
    – phils
    Dec 15, 2014 at 22:07
  • @phils: Sounds good; I'll update the answer. (Apparently add-dir-local-variable does not care about formatting.) Dec 15, 2014 at 22:11

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