Subject: 24.3.50; dired and directory variables

From: Michael Heerdegen <[email-masked]>
Date: Sun, 06 Apr 2014 14:55:19 +0200

Hello,

dired doesn't play well with directory local variables.  The manual
(info "(emacs) Directory Variables") seems to say that they would work
with dired, but I found several problems with that (all this in emacs
-Q):

1.  In dired, they (sometimes?) take effect only in subdirectories, but
not in the directory where they are specified.

Example:  In my ~, I create a .dir-locals.el with the content

((nil . ((a .  "hallo"))))

When I now open a dired buffer of ~, `a' is undefined.  When I open any
file below ~, `a' is bound as expected.

2.  Being able to use use `dired-listing-switches' as a directory
variable would obviously be very useful.  But it has no effect, even not
in subdirectories.  OTOH, using `dired-actual-switches' has an effect,
it leads to a sorting as expected, even (contrary to 1.) in the
directory that contains the dir locals file.

3.  `dir-locals-collect-variables' "destroys" any (subdirs . nil)
specification:

I change the .dir-locals.el in my ~ to the following content:

((nil . ((a .  "hallo")
         (subdirs . nil))))

and restart Emacs.

Now I dired ~.  After that, I visit any file somewhere under ~ (this can
be a regular file or a directory).  `a' will be bound in that buffer.

This doesn't happen if I don't dired ~ before.  The cause seems to be
this line in `dir-locals-collect-variables':

  (setq alist (delq subdirs alist))

which modifies the cached alist sturcture destructively (permanently!).
The `delq' should be a `remq', I guess.

Many thanks,

Michael.

In GNU Emacs 24.3.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.7)
 of 2014-03-28 on drachen
Windowing system distributor `The X.Org Foundation', version 11.0.11500000
System Description:	Debian GNU/Linux testing (jessie)