2 files changed, 25 insertions, 14 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 5e78a64a0ba..0e8d8f6961a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2009-08-15  Chong Yidong  <cyd@stupidchicken.com>
+
+        * buffer.c (set_buffer_internal_1)
+        (swap_out_buffer_local_variables): Check for unbound local
+        variables (Bug#4138).
+
 2009-08-14  Eli Zaretskii  <eliz@gnu.org>
 
         * process.c (create_pty): Fix last change.
diff --git a/src/buffer.c b/src/buffer.c
index f811f162ef2..580d5f004cd 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1921,12 +1921,14 @@ set_buffer_internal_1 (b)
 
   for (tail = b->local_var_alist; CONSP (tail); tail = XCDR (tail))
     {
-      valcontents = SYMBOL_VALUE (XCAR (XCAR (tail)));
-      if ((BUFFER_LOCAL_VALUEP (valcontents))
+      if (CONSP (XCAR (tail))
+          && SYMBOLP (XCAR (XCAR (tail)))
+          && (valcontents = SYMBOL_VALUE (XCAR (XCAR (tail))),
+              (BUFFER_LOCAL_VALUEP (valcontents)))
           && (tem = XBUFFER_LOCAL_VALUE (valcontents)->realvalue,
               (BOOLFWDP (tem) || INTFWDP (tem) || OBJFWDP (tem))))
-        /* Just reference the variable
-             to cause it to become set for this buffer.  */
+        /* Just reference the variable to cause it to become set for
+           this buffer.  */
         Fsymbol_value (XCAR (XCAR (tail)));
     }
 
@@ -1935,12 +1937,14 @@ set_buffer_internal_1 (b)
   if (old_buf)
     for (tail = old_buf->local_var_alist; CONSP (tail); tail = XCDR (tail))
       {
-        valcontents = SYMBOL_VALUE (XCAR (XCAR (tail)));
-        if ((BUFFER_LOCAL_VALUEP (valcontents))
+        if (CONSP (tail)
+            && SYMBOLP (XCAR (XCAR (tail)))
+            && (valcontents = SYMBOL_VALUE (XCAR (XCAR (tail))),
+                (BUFFER_LOCAL_VALUEP (valcontents)))
             && (tem = XBUFFER_LOCAL_VALUE (valcontents)->realvalue,
                 (BOOLFWDP (tem) || INTFWDP (tem) || OBJFWDP (tem))))
-          /* Just reference the variable
-               to cause it to become set for this buffer.  */
+          /* Just reference the variable to cause it to become set for
+             this buffer.  */
           Fsymbol_value (XCAR (XCAR (tail)));
       }
 }
@@ -2653,18 +2657,19 @@ static void
 swap_out_buffer_local_variables (b)
      struct buffer *b;
 {
-  Lisp_Object oalist, alist, sym, tem, buffer;
+  Lisp_Object oalist, alist, sym, buffer;
 
   XSETBUFFER (buffer, b);
   oalist = b->local_var_alist;
 
   for (alist = oalist; CONSP (alist); alist = XCDR (alist))
     {
-      sym = XCAR (XCAR (alist));
-
-      /* Need not do anything if some other buffer's binding is now encached.  */
-      tem = XBUFFER_LOCAL_VALUE (SYMBOL_VALUE (sym))->buffer;
-      if (EQ (tem, buffer))
+      if (CONSP (XCAR (alist))
+          && (sym = XCAR (XCAR (alist)), SYMBOLP (sym))
+          /* Need not do anything if some other buffer's binding is
+             now encached.  */
+          && EQ (XBUFFER_LOCAL_VALUE (SYMBOL_VALUE (sym))->buffer,
+                 buffer))
         {
           /* Symbol is set up for this buffer's old local value:
              swap it out!  */