Add the ability to exclude dir-locals from subdirs. (Bug#8100)

* lisp/files.el (dir-locals-collect-variables):
Add the ability to exclude subdirectories.

* doc/emacs/custom.texi (Directory Variables):
Give an example of excluding subdirectories.

* doc/lispref/variables.texi (Directory Local Variables):
Mention `(subdirs . nil)' alist element.

* etc/NEWS: Mention this addition.

* lisp/dired-x.el (dired-omit-here-always): Add `(subdirs . nil)' to locals.

8 files changed, 51 insertions, 8 deletions

diff --git a/doc/emacs/ChangeLog b/doc/emacs/ChangeLog
index 7a9c3ae3a47..8b94bf8f6dd 100644
--- a/doc/emacs/ChangeLog
+++ b/doc/emacs/ChangeLog
@@ -1,3 +1,8 @@
+2011-03-01  Glenn Morris  <rgm@gnu.org>
+
+        * custom.texi (Directory Variables):
+        Give an example of excluding subdirectories.
+
 2011-02-28  Eli Zaretskii  <eliz@gnu.org>
 
         * search.texi (Regexp Search): Move index entries about regexps to the
diff --git a/doc/emacs/custom.texi b/doc/emacs/custom.texi
index dfd55b13f18..9304e8bef08 100644
--- a/doc/emacs/custom.texi
+++ b/doc/emacs/custom.texi
@@ -1331,7 +1331,8 @@ corresponding alist applies to all the files in that subdirectory.
          (tab-width . 4)
          (fill-column . 80)))
  (c-mode . ((c-file-style . "BSD")))
- (java-mode . ((c-file-style . "BSD")))
+ (java-mode . ((c-file-style . "BSD")
+               (subdirs . nil)))
  ("src/imported"
   . ((nil . ((change-log-default-name . "ChangeLog.local"))))))
 @end example
@@ -1340,8 +1341,10 @@ corresponding alist applies to all the files in that subdirectory.
 This example shows some settings for a hypothetical project.  It sets
 @samp{indent-tabs-mode}, @code{tab-width}, and @code{fill-column} for
 any file in the project's directory tree, and it sets the indentation
-style for any C or Java source file.  Finally, it specifies a different
-@file{ChangeLog} file name for any file in the @file{src/imported}
+style for any C or Java source file.  The special @code{subdirs} element
+indicates that the Java mode settings are only to be applied in the
+current directory, not in any subdirectories.  Finally, it specifies a
+different @file{ChangeLog} file name for any file in the @file{src/imported}
 subdirectory of the directory where you put the @file{.dir-locals.el}
 file.
 
diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index c8925715f74..1a980f14f3d 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2011-03-01  Glenn Morris  <rgm@gnu.org>
+
+        * variables.texi (Directory Local Variables):
+        Mention `(subdirs . nil)' alist element.
+
 2011-02-28  Glenn Morris  <rgm@gnu.org>
 
         * variables.texi (Directory Local Variables): Mention the optional
diff --git a/doc/lispref/variables.texi b/doc/lispref/variables.texi
index c6af304416c..a68b2b6dd4e 100644
--- a/doc/lispref/variables.texi
+++ b/doc/lispref/variables.texi
@@ -1718,7 +1718,8 @@ directory-local variables.  The name of the file is
 The MS-DOS version of Emacs uses @file{_dir-locals.el} instead, due to
 limitations of the DOS filesystems.
 }.  A file by that name in a directory causes Emacs to apply its
-settings to any file in that directory or any of its subdirectories.
+settings to any file in that directory or any of its subdirectories
+(optionally, you can exclude subdirectories; see below).
 If some of the subdirectories have their own @file{.dir-locals.el}
 files, Emacs uses the settings from the deepest file it finds starting
 from the file's directory and moving up the directory tree.  The file
@@ -1749,7 +1750,10 @@ file's buffer turns on a mode that is derived from @var{major-mode},
 then the all the variables in the associated @var{alist} are applied;
 @var{alist} should be of the form @code{(@var{name} . @var{value})}.
 A special value @code{nil} for @var{major-mode} means the settings are
-applicable to any mode.
+applicable to any mode.  In @var{alist}, you can use a special
+@var{name}: @code{subdirs}.  If the associated value is
+@code{nil}, the alist is only applied to files in the relevant
+directory, not to those in any subdirectories.
 
 With the second form of @var{variables}, if @var{directory} is the
 initial substring of the file's directory, then @var{list} is applied
diff --git a/etc/NEWS b/etc/NEWS
index cfb788940d0..0777dcc3d2a 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -353,6 +353,11 @@ Just set shell-dir-cookie-re to an appropriate regexp.
 will turn on `whitespace-mode' for *vc-diff* buffers.  Modes should
 call `hack-dir-local-variables-non-file-buffer' to support this.
 
++++
+** You can prevent directory local variables from applying to subdirectories.
+Add an element (subdirs . nil) to the alist portion of any variables
+settings to indicate said section should not be applied to subdirectories.
+
 ** ERC changes
 
 *** New vars `erc-autojoin-timing' and `erc-autojoin-delay'.
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index e5abd0b93d7..5b8a5be8280 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2011-03-01  Glenn Morris  <rgm@gnu.org>
+
+        * files.el (dir-locals-collect-variables):
+        Add the ability to exclude subdirectories.  (Bug#8100)
+
+        * dired-x.el (dired-omit-here-always): Add `(subdirs . nil)' to locals.
+
 2011-02-28  Christoph Scholtes  <cschol2112@googlemail.com>
 
         * ido.el (ido-everywhere): Doc fix.
diff --git a/lisp/dired-x.el b/lisp/dired-x.el
index 816beb0034c..9941c7a0db5 100644
--- a/lisp/dired-x.el
+++ b/lisp/dired-x.el
@@ -786,6 +786,7 @@ See also `dired-enable-local-variables'."
                'hack-dir-local-variables-non-file-buffer "24.1")
 
 ;; Not sure this is worth having a dedicated command for...
+;; See the more general features in files-x.el.
 (defun dired-omit-here-always ()
   "Create `dir-locals-file' setting `dired-omit-mode' to t in `dired-mode'.
 If in a Dired buffer, reverts it."
@@ -798,7 +799,9 @@ replace it with a dir-locals-file `./%s'"
   (if (file-exists-p dir-locals-file)
       (message "File `./%s' already exists." dir-locals-file)
     (with-temp-buffer
-      (insert "((dired-mode . ((dired-omit-mode . t))))\n")
+      (insert "\
+\((dired-mode . ((subdirs . nil)
+                (dired-omit-mode . t))))\n")
       (write-file dir-locals-file))
     ;; Run extra-hooks and revert directory.
     (when (derived-mode-p 'dired-mode)
diff --git a/lisp/files.el b/lisp/files.el
index 5890bf9b8c9..bafae814756 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3394,8 +3394,19 @@ Return the new variables list."
                                  (cdr entry) root variables))))
              ((or (not key)
                   (derived-mode-p key))
-              (setq variables (dir-locals-collect-mode-variables
-                               (cdr entry) variables))))))
+              (let* ((alist (cdr entry))
+                     (subdirs (assq 'subdirs alist)))
+                (if (or (not subdirs)
+                        (progn
+                          (setq alist (delq subdirs alist))
+                          (cdr-safe subdirs))
+                        ;; TODO someone might want to extent this to allow
+                        ;; integer values for subdir, where N means
+                        ;; variables apply to this directory and N levels
+                        ;; below it (0 == nil).
+                        (equal root default-directory))
+                    (setq variables (dir-locals-collect-mode-variables
+                                     alist variables))))))))
       (error
        ;; The file's content might be invalid (e.g. have a merge conflict), but
        ;; that shouldn't prevent the user from opening the file.