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

2 files changed, 16 insertions, 4 deletions

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);
+          }
       }
   }