* lisp.h (XCONS, XSTRING, XSYMBOL, XFLOAT, XPROCESS, XWINDOW, XSUBR, XBUFFER):

Verify correct object type before returning pointer, using eassert.
* frame.h (XFRAME): Likewise.

* buffer.c (Frename_buffer, Fset_buffer_multibyte,
swap_out_buffer_local_variables, Fmove_overlay): Don't apply XSYMBOL, XBUFFER,
etc, to values that may be nil or of the wrong type.
* data.c (set_internal): Likewise.
* dispextern.h (WINDOW_WANTS_MODELINE_P, WINDOW_WANTS_HEADER_LINE_P): Likewise.
* fileio.c (auto_save_1): Likewise.
* insdel.c (check_markers): Likewise.
* marker.c (buf_charpos_to_bytepos, unchain_marker): Likewise.
* undo.c (record_insert): Likewise.
* vmsproc.c (child_sig): Likewise.
* window.c (unshow_buffer, window_loop): Likewise.
* xterm.c (x_erase_phys_cursor): Likewise.

13 files changed, 63 insertions, 32 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index ed700166530..1d09e191d7d 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,25 @@
+2000-03-30  Ken Raeburn  <raeburn@gnu.org>
+
+        * lisp.h (XCONS, XSTRING, XSYMBOL, XFLOAT, XPROCESS, XWINDOW,
+        XSUBR, XBUFFER): Verify correct object type before returning
+        pointer, using eassert.
+        * frame.h (XFRAME): Likewise.
+
+        * buffer.c (Frename_buffer, Fset_buffer_multibyte,
+        swap_out_buffer_local_variables, Fmove_overlay): Don't apply
+        XSYMBOL, XBUFFER, etc, to values that may be nil or of the wrong
+        type.
+        * data.c (set_internal): Likewise.
+        * dispextern.h (WINDOW_WANTS_MODELINE_P,
+        WINDOW_WANTS_HEADER_LINE_P): Likewise.
+        * fileio.c (auto_save_1): Likewise.
+        * insdel.c (check_markers): Likewise.
+        * marker.c (buf_charpos_to_bytepos, unchain_marker): Likewise.
+        * undo.c (record_insert): Likewise.
+        * vmsproc.c (child_sig): Likewise.
+        * window.c (unshow_buffer, window_loop): Likewise.
+        * xterm.c (x_erase_phys_cursor): Likewise.
+
 2000-03-30  Gerd Moellmann  <gerd@gnu.org>
 
         * xfns.c (free_image_cache): Free the cache structure itself
diff --git a/src/buffer.c b/src/buffer.c
index d54555d3242..848e9990776 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -887,14 +887,14 @@ This does not change the name of the visited file (if any).")
     error ("Empty string is invalid as a buffer name");
 
   tem = Fget_buffer (newname);
-  /* Don't short-circuit if UNIQUE is t.  That is a useful way to rename
-     the buffer automatically so you can create another with the original name.
-     It makes UNIQUE equivalent to
-     (rename-buffer (generate-new-buffer-name NEWNAME)).  */
-  if (NILP (unique) && XBUFFER (tem) == current_buffer)
-    return current_buffer->name;
   if (!NILP (tem))
     {
+      /* Don't short-circuit if UNIQUE is t.  That is a useful way to
+         rename the buffer automatically so you can create another
+         with the original name.  It makes UNIQUE equivalent to
+         (rename-buffer (generate-new-buffer-name NEWNAME)).  */
+      if (NILP (unique) && XBUFFER (tem) == current_buffer)
+        return current_buffer->name;
       if (!NILP (unique))
         newname = Fgenerate_new_buffer_name (newname, current_buffer->name);
       else
@@ -1815,7 +1815,7 @@ but the contents viewed as characters do change.")
       TEMP_SET_PT_BOTH (PT_BYTE, PT_BYTE);
 
       tail = BUF_MARKERS (current_buffer);
-      while (XSYMBOL (tail) != XSYMBOL (Qnil))
+      while (! NILP (tail))
         {
           XMARKER (tail)->charpos = XMARKER (tail)->bytepos;
           tail = XMARKER (tail)->chain;
@@ -1880,7 +1880,7 @@ but the contents viewed as characters do change.")
          It is also a signal that it should never create a marker.  */
       BUF_MARKERS (current_buffer) = Qnil;
 
-      while (XSYMBOL (tail) != XSYMBOL (Qnil))
+      while (! NILP (tail))
         {
           XMARKER (tail)->bytepos
             = advance_to_char_boundary (XMARKER (tail)->bytepos);
@@ -1996,7 +1996,7 @@ swap_out_buffer_local_variables (b)
 
       /* Need not do anything if some other buffer's binding is now encached.  */
       tem = XBUFFER_LOCAL_VALUE (XSYMBOL (sym)->value)->buffer;
-      if (XBUFFER (tem) == current_buffer)
+      if (BUFFERP (tem) && XBUFFER (tem) == current_buffer)
         {
           /* Symbol is set up for this buffer's old local value.
              Set it up for the current buffer with the default value.  */
@@ -3166,7 +3166,7 @@ buffer.")
 
   obuffer = Fmarker_buffer (OVERLAY_START (overlay));
   b = XBUFFER (buffer);
-  ob = XBUFFER (obuffer);
+  ob = BUFFERP (obuffer) ? XBUFFER (obuffer) : (struct buffer *) 0;
 
   /* If the overlay has changed buffers, do a thorough redisplay.  */
   if (!EQ (buffer, obuffer))
diff --git a/src/data.c b/src/data.c
index f736f7f6c81..c267c5540f0 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1012,7 +1012,8 @@ set_internal (symbol, newval, buf, bindflag)
          isn't the right one, or if it's a Lisp_Buffer_Local_Value and
          the default binding is loaded, the loaded binding may be the
          wrong one.  */
-      if (buf != XBUFFER (XBUFFER_LOCAL_VALUE (valcontents)->buffer)
+      if (!BUFFERP (XBUFFER_LOCAL_VALUE (valcontents)->buffer)
+          || buf != XBUFFER (XBUFFER_LOCAL_VALUE (valcontents)->buffer)
           || (XBUFFER_LOCAL_VALUE (valcontents)->check_frame
               && !EQ (selected_frame, XBUFFER_LOCAL_VALUE (valcontents)->frame))
           || (BUFFER_LOCAL_VALUEP (valcontents)
diff --git a/src/dispextern.h b/src/dispextern.h
index 76578b8fde4..2665cf38d3a 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1066,6 +1066,7 @@ extern struct glyph_row scratch_glyph_row;
      (!MINI_WINDOW_P (W)                                                \
       && !(W)->pseudo_window_p                                          \
       && FRAME_WANTS_MODELINE_P (XFRAME (WINDOW_FRAME (W)))             \
+      && BUFFERP ((W)->buffer)                                          \
       && !NILP (XBUFFER ((W)->buffer)->mode_line_format))
 
 /* Value is non-zero if window W wants a top line.  */
@@ -1074,6 +1075,7 @@ extern struct glyph_row scratch_glyph_row;
      (!MINI_WINDOW_P (W)                                                \
       && !(W)->pseudo_window_p                                          \
       && FRAME_WANTS_MODELINE_P (XFRAME (WINDOW_FRAME (W)))             \
+      && BUFFERP ((W)->buffer)                                          \
       && !NILP (XBUFFER ((W)->buffer)->header_line_format))
 
      
diff --git a/src/fileio.c b/src/fileio.c
index 726d3fca803..b68ebfc5b71 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5144,7 +5144,8 @@ auto_save_1 ()
   struct stat st;
 
   /* Get visited file's mode to become the auto save file's mode.  */
-  if (stat (XSTRING (current_buffer->filename)->data, &st) >= 0)
+  if (! NILP (current_buffer->filename)
+      && stat (XSTRING (current_buffer->filename)->data, &st) >= 0)
     /* But make sure we can overwrite it later!  */
     auto_save_mode_bits = st.st_mode | 0600;
   else
diff --git a/src/frame.h b/src/frame.h
index 724a9ee916b..8183b516608 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -383,7 +383,7 @@ struct frame
 
 typedef struct frame *FRAME_PTR;
 
-#define XFRAME(p) ((struct frame *) XPNTR (p))
+#define XFRAME(p) (eassert (GC_FRAMEP(p)),(struct frame *) XPNTR (p))
 #define XSETFRAME(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FRAME))
 
 /* Given a window, return its frame as a Lisp_Object.  */
diff --git a/src/insdel.c b/src/insdel.c
index 3cab83711ba..9facec4cf34 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -83,7 +83,7 @@ check_markers ()
 
   tail = BUF_MARKERS (current_buffer);
 
-  while (XSYMBOL (tail) != XSYMBOL (Qnil))
+  while (! NILP (tail))
     {
       if (XMARKER (tail)->buffer->text != current_buffer->text)
         abort ();
diff --git a/src/lisp.h b/src/lisp.h
index 54a3bdd5855..13e734a73ea 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -432,11 +432,11 @@ extern Lisp_Object make_number ();
 
 /* Extract a value or address from a Lisp_Object.  */
 
-#define XCONS(a) ((struct Lisp_Cons *) XPNTR(a))
+#define XCONS(a) (eassert (GC_CONSP(a)),(struct Lisp_Cons *) XPNTR(a))
 #define XVECTOR(a) ((struct Lisp_Vector *) XPNTR(a))
-#define XSTRING(a) ((struct Lisp_String *) XPNTR(a))
-#define XSYMBOL(a) ((struct Lisp_Symbol *) XPNTR(a))
-#define XFLOAT(a) ((struct Lisp_Float *) XPNTR(a))
+#define XSTRING(a) (eassert (GC_STRINGP(a)),(struct Lisp_String *) XPNTR(a))
+#define XSYMBOL(a) (eassert (GC_SYMBOLP(a)),(struct Lisp_Symbol *) XPNTR(a))
+#define XFLOAT(a) (eassert (GC_FLOATP(a)),(struct Lisp_Float *) XPNTR(a))
 
 /* Misc types.  */
 #define XMISC(a)   ((union Lisp_Misc *) XPNTR(a))
@@ -451,10 +451,10 @@ extern Lisp_Object make_number ();
 #define XKBOARD_OBJFWD(a) (&(XMISC(a)->u_kboard_objfwd))
 
 /* Pseudovector types.  */
-#define XPROCESS(a) ((struct Lisp_Process *) XPNTR(a))
-#define XWINDOW(a) ((struct window *) XPNTR(a))
-#define XSUBR(a) ((struct Lisp_Subr *) XPNTR(a))
-#define XBUFFER(a) ((struct buffer *) XPNTR(a))
+#define XPROCESS(a) (eassert (GC_PROCESSP(a)),(struct Lisp_Process *) XPNTR(a))
+#define XWINDOW(a) (eassert (GC_WINDOWP(a)),(struct window *) XPNTR(a))
+#define XSUBR(a) (eassert (GC_SUBRP(a)),(struct Lisp_Subr *) XPNTR(a))
+#define XBUFFER(a) (eassert (GC_BUFFERP(a)),(struct buffer *) XPNTR(a))
 #define XCHAR_TABLE(a) ((struct Lisp_Char_Table *) XPNTR(a))
 #define XBOOL_VECTOR(a) ((struct Lisp_Bool_Vector *) XPNTR(a))
 
diff --git a/src/marker.c b/src/marker.c
index 7e4cd4fa343..5b01738cf9d 100644
--- a/src/marker.c
+++ b/src/marker.c
@@ -168,7 +168,7 @@ buf_charpos_to_bytepos (b, charpos)
     CONSIDER (cached_charpos, cached_bytepos);
 
   tail = BUF_MARKERS (b);
-  while (XSYMBOL (tail) != XSYMBOL (Qnil))
+  while (! NILP (tail))
     {
       CONSIDER (XMARKER (tail)->charpos, XMARKER (tail)->bytepos);
 
@@ -336,7 +336,7 @@ buf_bytepos_to_charpos (b, bytepos)
     CONSIDER (cached_bytepos, cached_charpos);
 
   tail = BUF_MARKERS (b);
-  while (XSYMBOL (tail) != XSYMBOL (Qnil))
+  while (! NILP (tail))
     {
       CONSIDER (XMARKER (tail)->bytepos, XMARKER (tail)->charpos);
 
@@ -747,7 +747,7 @@ unchain_marker (marker)
 
   tail = BUF_MARKERS (b);
   prev = Qnil;
-  while (XSYMBOL (tail) != XSYMBOL (Qnil))
+  while (! GC_NILP (tail))
     {
       next = XMARKER (tail)->chain;
       XUNMARK (next);
diff --git a/src/undo.c b/src/undo.c
index 96e3eeb687c..a498f2aae72 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -54,7 +54,8 @@ record_insert (beg, length)
   if (NILP (pending_boundary))
     pending_boundary = Fcons (Qnil, Qnil);
 
-  if (current_buffer != XBUFFER (last_undo_buffer))
+  if (!BUFFERP (last_undo_buffer)
+      || current_buffer != XBUFFER (last_undo_buffer))
     Fundo_boundary ();
   XSETBUFFER (last_undo_buffer, current_buffer);
 
diff --git a/src/vmsproc.c b/src/vmsproc.c
index 122cf08bd36..15e2c9d5e61 100644
--- a/src/vmsproc.c
+++ b/src/vmsproc.c
@@ -758,7 +758,7 @@ child_sig (vs)
   pid = vs->pid;
   sys$setef (vs->eventFlag);
 
-  for (tail = Vprocess_alist; XSYMBOL (tail) != XSYMBOL (Qnil); tail = XCDR (tail))
+  for (tail = Vprocess_alist; ! NILP (tail); tail = XCDR (tail))
     {
       proc = XCDR (XCAR (tail));
       p = XPROCESS (proc);
@@ -766,7 +766,7 @@ child_sig (vs)
         break;
     }
 
-  if (XSYMBOL (tail) == XSYMBOL (Qnil))
+  if (NILP (tail))
     return;
 
   p->status = Fcons (Qexit, Fcons (make_number (vs->exitStatus), Qnil))
diff --git a/src/window.c b/src/window.c
index 95edbf8e13e..72547cad4b1 100644
--- a/src/window.c
+++ b/src/window.c
@@ -905,7 +905,8 @@ unshow_buffer (w)
      So don't clobber point in that buffer.  */
   if (! EQ (buf, XWINDOW (selected_window)->buffer)
       /* This line helps to fix Horsley's testbug.el bug.  */
-      && !(w != XWINDOW (b->last_selected_window)
+      && !(WINDOWP (b->last_selected_window)
+           && w != XWINDOW (b->last_selected_window)
            && EQ (buf, XWINDOW (b->last_selected_window)->buffer)))
     temp_set_point_both (b,
                          clip_to_bounds (BUF_BEGV (b),
@@ -915,7 +916,8 @@ unshow_buffer (w)
                                          marker_byte_position (w->pointm),
                                          BUF_ZV_BYTE (b)));
   
-  if (w == XWINDOW (b->last_selected_window))
+  if (WINDOWP (b->last_selected_window)
+      && w == XWINDOW (b->last_selected_window))
     b->last_selected_window = Qnil;
 }
 
@@ -1633,7 +1635,8 @@ window_loop (type, obj, mini, frames)
           case GET_LARGEST_WINDOW:
             /* Ignore dedicated windows and minibuffers.  */
             if (MINI_WINDOW_P (XWINDOW (w))
-                || !NILP (XWINDOW (w)->dedicated))
+                || !NILP (XWINDOW (w)->dedicated)
+                || NILP (best_window))
               break;
             {
               struct window *best_window_ptr = XWINDOW (best_window);
diff --git a/src/xterm.c b/src/xterm.c
index 216c633a584..ed08485904d 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -10225,7 +10225,8 @@ x_erase_phys_cursor (w)
          
   /* If the cursor is in the mouse face area, redisplay that when
      we clear the cursor.  */
-  if (w == XWINDOW (dpyinfo->mouse_face_window)
+  if (! NILP (dpyinfo->mouse_face_window)
+      && w == XWINDOW (dpyinfo->mouse_face_window)
       && (vpos > dpyinfo->mouse_face_beg_row
           || (vpos == dpyinfo->mouse_face_beg_row
               && hpos >= dpyinfo->mouse_face_beg_col))