Widen modiff counts to avoid wraparound

Widen modification counts to at least 64 bits, to make
wraparound practically impossible.
* doc/lispref/buffers.texi (Buffer Modification):
Don’t say the modification-count can wrap around.
* src/buffer.c (Frestore_buffer_modified_p, Fbuffer_swap_text)
(modify_overlay):
* src/insdel.c (insert_1_both, insert_from_string_1)
(insert_from_gap, insert_from_buffer_1)
(adjust_after_replace, replace_range, replace_range_2)
(del_range_2, modify_text):
* src/textprop.c (modify_text_properties):
Use modiff_incr instead of incrementing	directly.
(Fbuffer_modified_tick, Fbuffer_chars_modified_tick):
Don’t assume modification counts fit into fixnums.
* src/buffer.h (struct buffer_text, struct buffer):
* src/cmds.c (internal_self_insert):
* src/fileio.c (Finsert_file_contents):
* src/indent.c (last_known_column_modified):
* src/keyboard.c (command_loop_1):
* src/marker.c (cached_modiff):
* src/syntax.c (find_start_modiff, parse_sexp_propertize)
(find_defun_start):
* src/window.h (struct window):
Use modiff_count for modification counts.
* src/editfns.c (Fsubst_char_in_region):
Copy instead of incrementing modification counts,
since integer overflow checking is not needed here.
* src/lisp.h (modiff_count): New type.
(modiff_incr, modiff_to_integer): New inline functions.
* src/pdumper.c (dump_buffer): Update hash.

1 files changed, 9 insertions, 9 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 82cc2ebfbf9..d3528ac50e9 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -422,20 +422,20 @@ struct buffer_text
     ptrdiff_t gpt_byte;		/* Byte pos of gap in buffer.  */
     ptrdiff_t z_byte;		/* Byte pos of end of buffer.  */
     ptrdiff_t gap_size;		/* Size of buffer's gap.  */
-    EMACS_INT modiff;		/* This counts buffer-modification events
+    modiff_count modiff;	/* This counts buffer-modification events
 				   for this buffer.  It is incremented for
 				   each such event, and never otherwise
 				   changed.  */
-    EMACS_INT chars_modiff;	/* This is modified with character change
+    modiff_count chars_modiff;	/* This is modified with character change
 				   events for this buffer.  It is set to
 				   modiff for each such event, and never
 				   otherwise changed.  */
-    EMACS_INT save_modiff;	/* Previous value of modiff, as of last
+    modiff_count save_modiff;	/* Previous value of modiff, as of last
 				   time buffer visited or saved a file.  */
 
-    EMACS_INT overlay_modiff;	/* Counts modifications to overlays.  */
+    modiff_count overlay_modiff; /* Counts modifications to overlays.  */
 
-    EMACS_INT compact;		/* Set to modiff each time when compact_buffer
+    modiff_count compact;	/* Set to modiff each time when compact_buffer
 				   is called for this buffer.  */
 
     /* Minimum value of GPT - BEG since last redisplay that finished.  */
@@ -446,12 +446,12 @@ struct buffer_text
 
     /* MODIFF as of last redisplay that finished; if it matches MODIFF,
        beg_unchanged and end_unchanged contain no useful information.  */
-    EMACS_INT unchanged_modified;
+    modiff_count unchanged_modified;
 
     /* BUF_OVERLAY_MODIFF of current buffer, as of last redisplay that
        finished; if it matches BUF_OVERLAY_MODIFF, beg_unchanged and
        end_unchanged contain no useful information.  */
-    EMACS_INT overlay_unchanged_modified;
+    modiff_count overlay_unchanged_modified;
 
     /* Properties of this buffer's text.  */
     INTERVAL intervals;
@@ -812,11 +812,11 @@ struct buffer
   off_t modtime_size;
 
   /* The value of text->modiff at the last auto-save.  */
-  EMACS_INT auto_save_modified;
+  modiff_count auto_save_modified;
 
   /* The value of text->modiff at the last display error.
      Redisplay of this buffer is inhibited until it changes again.  */
-  EMACS_INT display_error_modiff;
+  modiff_count display_error_modiff;
 
   /* The time at which we detected a failure to auto-save,
      Or 0 if we didn't have a failure.  */