Fix and doc-fix for `buffer-local-variables'.

* src/buffer.c (Fbuffer_local_variables)
(buffer_lisp_local_variables): Handle unbound vars correctly;
don't let Qunbound leak into Lisp.

* doc/lispref/variables.texi (Creating Buffer-Local): Minor clarification
to buffer-local-variables doc.

Fixes: debbugs:10715

5 files changed, 38 insertions, 9 deletions

diff --git a/admin/notes/bugtracker b/admin/notes/bugtracker
index dd1ea46ceb2..3c24212ea10 100644
--- a/admin/notes/bugtracker
+++ b/admin/notes/bugtracker
@@ -640,3 +640,14 @@ I think you also have to add them to 'tags' and 'tags_single_letter'
 in /usr/share/perl5/Debbugs/Config.pm.
 And update /var/www/Developer.html with a description of what the tag means.
 And the "valid tags" list in /var/www/index.html.
+
+** Backups
+
+The FSF sysadmins handle multi-generational backups of the filesystem
+on debbugs.gnu.org.  But if you really want to have your own backup of
+the bug database, you can use rsync (this requires login access to
+debbugs.gnu.org):
+
+ rsync -azvv -e ssh USER@debbugs.gnu.org:/var/lib/debbugs/ DEST
+
+Note that this occupies well over 1G of disk space.
diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 1a7c71232c6..04d1234be06 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2012-02-07  Chong Yidong  <cyd@gnu.org>
+
+        * variables.texi (Creating Buffer-Local): Minor clarification
+        to buffer-local-variables doc (Bug#10715).
+
 2012-02-07  Glenn Morris  <rgm@gnu.org>
 
         * display.texi (ImageMagick Images): General update.
diff --git a/doc/lispref/variables.texi b/doc/lispref/variables.texi
index bdb16cd10a8..ab3a4edc0ac 100644
--- a/doc/lispref/variables.texi
+++ b/doc/lispref/variables.texi
@@ -1317,11 +1317,12 @@ value (@pxref{Default Value}) of @var{variable} instead.
 
 @defun buffer-local-variables &optional buffer
 This function returns a list describing the buffer-local variables in
-buffer @var{buffer}.  (If @var{buffer} is omitted, the current buffer is
-used.)  It returns an association list (@pxref{Association Lists}) in
-which each element contains one buffer-local variable and its value.
-However, when a variable's buffer-local binding in @var{buffer} is void,
-then the variable appears directly in the resulting list.
+buffer @var{buffer}.  (If @var{buffer} is omitted, the current buffer
+is used.)  Normally, each list element has the form
+@w{@code{(@var{sym} . @var{val})}}, where @var{sym} is a buffer-local
+variable (a symbol) and @var{val} is its buffer-local value.  But when
+a variable's buffer-local binding in @var{buffer} is void, its list
+element is just @var{sym}.
 
 @example
 @group
diff --git a/src/ChangeLog b/src/ChangeLog
index 5e4d995d857..71af862cdac 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2012-02-07  Chong Yidong  <cyd@gnu.org>
+
+        * buffer.c (Fbuffer_local_variables)
+        (buffer_lisp_local_variables): Handle unbound vars correctly;
+        don't let Qunbound leak into Lisp.
+
 2012-02-07  Glenn Morris  <rgm@gnu.org>
 
         * image.c (Fimagemagick_types): Doc fix.
diff --git a/src/buffer.c b/src/buffer.c
index 01418956c8d..a6f61a1936a 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1022,7 +1022,10 @@ buffer_lisp_local_variables (struct buffer *buf)
       if (buf != current_buffer)
         val = XCDR (elt);
 
-      result = Fcons (Fcons (XCAR (elt), val), result);
+      result = Fcons (EQ (val, Qunbound)
+                      ? XCAR (elt)
+                      : Fcons (XCAR (elt), val),
+                      result);
     }
 
   return result;
@@ -1064,9 +1067,12 @@ No argument or nil as argument means use current buffer as BUFFER.  */)
         idx = PER_BUFFER_IDX (offset);
         if ((idx == -1 || PER_BUFFER_VALUE_P (buf, idx))
             && SYMBOLP (PER_BUFFER_SYMBOL (offset)))
-          result = Fcons (Fcons (PER_BUFFER_SYMBOL (offset),
-                                 PER_BUFFER_VALUE (buf, offset)),
-                          result);
+          {
+            Lisp_Object sym = PER_BUFFER_SYMBOL (offset);
+            Lisp_Object val = PER_BUFFER_VALUE (buf, offset);
+            result = Fcons (EQ (val, Qunbound) ? sym : Fcons (sym, val),
+                            result);
+          }
       }
   }