tab-width ignored in .dir-locals.el

[Grant Edwards]

How do you set the tab width for C-mode in a .dir-locals.el file?

All the documentation I can find says this should work:

------------------------------------------------------------------------
((nil . ((indent-tabs-mode . t)
         (tab-width . 4)
              ))
 (c-mode . ((c-file-style . "BSD")
            (subdirs . t)
                        ))
 )
------------------------------------------------------------------------

But when I edit a .c file, the tab width is always 8.

What am I doing wrong?

I tried adding (subdirs . t) to the first list, but that made no difference.