Use INTERNAL_FIELD for conses and overlays.

* src/lisp.h (struct Lisp_Cons): Use INTERNAL_FIELD.
Remove obsolete comment.
(MVAR): New macro.
(struct Lisp_Overlay): Use INTERNAL_FIELD.
* src/alloc.c, src/buffer.c, src/buffer.h, src/fns.c: Adjust users.
* admin/coccinelle/overlay.cocci: Semantic patch to replace direct
access to Lisp_Object members of struct Lisp_Overlay to MVAR.

6 files changed, 60 insertions, 39 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 3bb9c2b4eef..a6913d1ad78 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,14 @@
 2012-08-01  Dmitry Antipov  <dmantipov@yandex.ru>
 
+        Use INTERNAL_FIELD for conses and overlays.
+        * lisp.h (struct Lisp_Cons): Use INTERNAL_FIELD.
+        Remove obsolete comment.
+        (MVAR): New macro.
+        (struct Lisp_Overlay): Use INTERNAL_FIELD.
+        * alloc.c, buffer.c, buffer.h, fns.c: Adjust users.
+
+2012-08-01  Dmitry Antipov  <dmantipov@yandex.ru>
+
         Use INTERNAL_FIELD for symbols.
         * lisp.h (SVAR): New macro.  Adjust users.
         * alloc.c, bytecode.c, cmds.c, data.c, doc.c, eval.c:
diff --git a/src/alloc.c b/src/alloc.c
index 8207f022a12..2d5149a6772 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2686,7 +2686,7 @@ free_cons (struct Lisp_Cons *ptr)
 {
   ptr->u.chain = cons_free_list;
 #if GC_MARK_STACK
-  ptr->car = Vdead;
+  CVAR (ptr, car) = Vdead;
 #endif
   cons_free_list = ptr;
   consing_since_gc -= sizeof *ptr;
@@ -4295,7 +4295,7 @@ live_cons_p (struct mem_node *m, void *p)
               && offset < (CONS_BLOCK_SIZE * sizeof b->conses[0])
               && (b != cons_block
                   || offset / sizeof b->conses[0] < cons_block_index)
-              && !EQ (((struct Lisp_Cons *) p)->car, Vdead));
+              && !EQ (CVAR ((struct Lisp_Cons *) p, car), Vdead));
     }
   else
     return 0;
@@ -5837,9 +5837,9 @@ mark_overlay (struct Lisp_Overlay *ptr)
   for (; ptr && !ptr->gcmarkbit; ptr = ptr->next)
     {
       ptr->gcmarkbit = 1;
-      mark_object (ptr->start);
-      mark_object (ptr->end);
-      mark_object (ptr->plist);
+      mark_object (MVAR (ptr, start));
+      mark_object (MVAR (ptr, end));
+      mark_object (MVAR (ptr, plist));
     }
 }
 
@@ -6169,14 +6169,14 @@ mark_object (Lisp_Object arg)
         CHECK_ALLOCATED_AND_LIVE (live_cons_p);
         CONS_MARK (ptr);
         /* If the cdr is nil, avoid recursion for the car.  */
-        if (EQ (ptr->u.cdr, Qnil))
+        if (EQ (CVAR (ptr, u.cdr), Qnil))
           {
-            obj = ptr->car;
+            obj = CVAR (ptr, car);
             cdr_count = 0;
             goto loop;
           }
-        mark_object (ptr->car);
-        obj = ptr->u.cdr;
+        mark_object (CVAR (ptr, car));
+        obj = CVAR (ptr, u.cdr);
         cdr_count++;
         if (cdr_count == mark_object_loop_halt)
           abort ();
@@ -6325,7 +6325,7 @@ gc_sweep (void)
                         cblk->conses[pos].u.chain = cons_free_list;
                         cons_free_list = &cblk->conses[pos];
 #if GC_MARK_STACK
-                        cons_free_list->car = Vdead;
+                        CVAR (cons_free_list, car) = Vdead;
 #endif
                       }
                     else
diff --git a/src/buffer.c b/src/buffer.c
index e70360f5173..8b7f524e27a 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -417,17 +417,17 @@ copy_overlays (struct buffer *b, struct Lisp_Overlay *list)
       Lisp_Object overlay, start, end;
       struct Lisp_Marker *m;
 
-      eassert (MARKERP (list->start));
-      m = XMARKER (list->start);
+      eassert (MARKERP (MVAR (list, start)));
+      m = XMARKER (MVAR (list, start));
       start = build_marker (b, m->charpos, m->bytepos);
       XMARKER (start)->insertion_type = m->insertion_type;
 
-      eassert (MARKERP (list->end));
-      m = XMARKER (list->end);
+      eassert (MARKERP (MVAR (list, end)));
+      m = XMARKER (MVAR (list, end));
       end = build_marker (b, m->charpos, m->bytepos);
       XMARKER (end)->insertion_type = m->insertion_type;
 
-      overlay = build_overlay (start, end, Fcopy_sequence (list->plist));
+      overlay = build_overlay (start, end, Fcopy_sequence (MVAR (list, plist)));
       if (tail)
         tail = tail->next = XOVERLAY (overlay);
       else
@@ -657,10 +657,11 @@ CLONE nil means the indirect buffer's state is reset to default values.  */)
 static void
 drop_overlay (struct buffer *b, struct Lisp_Overlay *ov)
 {
-  eassert (b == XBUFFER (Fmarker_buffer (ov->start)));
-  modify_overlay (b, marker_position (ov->start), marker_position (ov->end));
-  Fset_marker (ov->start, Qnil, Qnil);
-  Fset_marker (ov->end, Qnil, Qnil);
+  eassert (b == XBUFFER (Fmarker_buffer (MVAR (ov, start))));
+  modify_overlay (b, marker_position (MVAR (ov, start)),
+                  marker_position (MVAR (ov, end)));
+  Fset_marker (MVAR (ov, start), Qnil, Qnil);
+  Fset_marker (MVAR (ov, end), Qnil, Qnil);
 
 }
 
@@ -3886,7 +3887,7 @@ OVERLAY.  */)
 {
   CHECK_OVERLAY (overlay);
 
-  return Fcopy_sequence (XOVERLAY (overlay)->plist);
+  return Fcopy_sequence (MVAR (XOVERLAY (overlay), plist));
 }
 
 
@@ -4062,7 +4063,7 @@ DEFUN ("overlay-get", Foverlay_get, Soverlay_get, 2, 2, 0,
   (Lisp_Object overlay, Lisp_Object prop)
 {
   CHECK_OVERLAY (overlay);
-  return lookup_char_property (XOVERLAY (overlay)->plist, prop, 0);
+  return lookup_char_property (MVAR (XOVERLAY (overlay), plist), prop, 0);
 }
 
 DEFUN ("overlay-put", Foverlay_put, Soverlay_put, 3, 3, 0,
@@ -4077,7 +4078,7 @@ VALUE will be returned.*/)
 
   buffer = Fmarker_buffer (OVERLAY_START (overlay));
 
-  for (tail = XOVERLAY (overlay)->plist;
+  for (tail = MVAR (XOVERLAY (overlay), plist);
        CONSP (tail) && CONSP (XCDR (tail));
        tail = XCDR (XCDR (tail)))
     if (EQ (XCAR (tail), prop))
@@ -4088,8 +4089,8 @@ VALUE will be returned.*/)
       }
   /* It wasn't in the list, so add it to the front.  */
   changed = !NILP (value);
-  XOVERLAY (overlay)->plist
-    = Fcons (prop, Fcons (value, XOVERLAY (overlay)->plist));
+  MVAR (XOVERLAY (overlay), plist)
+    = Fcons (prop, Fcons (value, MVAR (XOVERLAY (overlay), plist)));
  found:
   if (! NILP (buffer))
     {
diff --git a/src/buffer.h b/src/buffer.h
index b9a2c9c7dce..cf571e06b53 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -986,15 +986,15 @@ BUF_FETCH_MULTIBYTE_CHAR (struct buffer *buf, ptrdiff_t pos)
 
 /* Return the marker that stands for where OV starts in the buffer.  */
 
-#define OVERLAY_START(OV) (XOVERLAY (OV)->start)
+#define OVERLAY_START(OV) MVAR (XOVERLAY (OV), start)
 
 /* Return the marker that stands for where OV ends in the buffer.  */
 
-#define OVERLAY_END(OV) (XOVERLAY (OV)->end)
+#define OVERLAY_END(OV) MVAR (XOVERLAY (OV), end)
 
 /* Return the plist of overlay OV.  */
 
-#define OVERLAY_PLIST(OV) XOVERLAY ((OV))->plist
+#define OVERLAY_PLIST(OV) MVAR (XOVERLAY (OV), plist)
 
 /* Return the actual buffer position for the marker P.
    We assume you know which buffer it's pointing into.  */
diff --git a/src/fns.c b/src/fns.c
index 0ff2877ea5e..a8c8cb283b0 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2053,8 +2053,8 @@ internal_equal (register Lisp_Object o1, register Lisp_Object o2, int depth, int
               || !internal_equal (OVERLAY_END (o1), OVERLAY_END (o2),
                                   depth + 1, props))
             return 0;
-          o1 = XOVERLAY (o1)->plist;
-          o2 = XOVERLAY (o2)->plist;
+          o1 = MVAR (XOVERLAY (o1), plist);
+          o2 = MVAR (XOVERLAY (o2), plist);
           goto tail_recurse;
         }
       if (MARKERP (o1))
diff --git a/src/lisp.h b/src/lisp.h
index 5e2195ce01d..2928f92df37 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -637,17 +637,22 @@ typedef struct interval *INTERVAL;
 #define CHECK_STRING_OR_BUFFER(x) \
   CHECK_TYPE (STRINGP (x) || BUFFERP (x), Qbuffer_or_string_p, x)
 
-
-/* In a cons, the markbit of the car is the gc mark bit */
+/* Most code should use this macro to
+   access Lisp fields in struct Lisp_Cons.  */
+
+#define CVAR(cons, field) ((cons)->INTERNAL_FIELD (field))
 
 struct Lisp_Cons
   {
-    /* Please do not use the names of these elements in code other
-       than the core lisp implementation.  Use XCAR and XCDR below.  */
-    Lisp_Object car;
+    /* Car of this cons cell.  */
+    Lisp_Object INTERNAL_FIELD (car);
+
     union
     {
-      Lisp_Object cdr;
+      /* Cdr of this cons cell.  */
+      Lisp_Object INTERNAL_FIELD (cdr);
+
+      /* Used to chain conses on a free list.  */
       struct Lisp_Cons *chain;
     } u;
   };
@@ -659,8 +664,8 @@ struct Lisp_Cons
    fields are not accessible as lvalues.  (What if we want to switch to
    a copying collector someday?  Cached cons cell field addresses may be
    invalidated at arbitrary points.)  */
-#define XCAR_AS_LVALUE(c) (XCONS ((c))->car)
-#define XCDR_AS_LVALUE(c) (XCONS ((c))->u.cdr)
+#define XCAR_AS_LVALUE(c) (CVAR (XCONS (c), car))
+#define XCDR_AS_LVALUE(c) (CVAR (XCONS (c), u.cdr))
 
 /* Use these from normal code.  */
 #define XCAR(c) LISP_MAKE_RVALUE (XCAR_AS_LVALUE (c))
@@ -1261,7 +1266,11 @@ enum DEFAULT_HASH_SIZE { DEFAULT_HASH_SIZE = 65 };
 
 #define DEFAULT_REHASH_SIZE 1.5
 
-
+/* Most code should use this macro to access
+   Lisp fields in a different misc objects.  */
+
+#define MVAR(misc, field) ((misc)->INTERNAL_FIELD (field))
+
 /* These structures are used for various misc types.  */
 
 struct Lisp_Misc_Any            /* Supertype of all Misc types.  */
@@ -1331,7 +1340,9 @@ struct Lisp_Overlay
     unsigned gcmarkbit : 1;
     int spacer : 15;
     struct Lisp_Overlay *next;
-    Lisp_Object start, end, plist;
+    Lisp_Object INTERNAL_FIELD (start);
+    Lisp_Object INTERNAL_FIELD (end);
+    Lisp_Object INTERNAL_FIELD (plist);
   };
 
 /* Hold a C pointer for later use.