Remove unportable assumption about struct layout (Bug#8884).

* buffer.c (clone_per_buffer_values): Don't assume that
sizeof (struct buffer) is a multiple of sizeof (Lisp_Object).
This isn't true in general, and it's particularly not true
if Emacs is configured with --with-wide-int.
* buffer.h (FIRST_FIELD_PER_BUFFER, LAST_FIELD_PER_BUFFER):
New macros, used in the buffer.c change.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 4643e0d9d0e..06864dd5789 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -612,6 +612,7 @@ struct buffer
   /* Everything from here down must be a Lisp_Object.  */
   /* buffer-local Lisp variables start at `undo_list',
      tho only the ones from `name' on are GC'd normally.  */
+  #define FIRST_FIELD_PER_BUFFER undo_list
 
   /* Changes in the buffer are recorded here for undo.
      t means don't record anything.
@@ -846,6 +847,9 @@ struct buffer
      t means to use hollow box cursor.
      See `cursor-type' for other values.  */
   Lisp_Object BUFFER_INTERNAL_FIELD (cursor_in_non_selected_windows);
+
+  /* This must be the last field in the above list.  */
+  #define LAST_FIELD_PER_BUFFER cursor_in_non_selected_windows
 };