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/insdel.c b/src/insdel.c
index a6f006a521d..fd725ac8785 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -903,7 +903,7 @@ insert_1_both (const char *string,
      the insertion.  This, together with recording the insertion,
      will add up to the right stuff in the undo list.  */
   record_insert (PT, nchars);
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 
   memcpy (GPT_ADDR, string, nbytes);
@@ -1031,7 +1031,7 @@ insert_from_string_1 (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 #endif
 
   record_insert (PT, nchars);
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 
   GAP_SIZE -= outgoing_nbytes;
@@ -1088,7 +1088,7 @@ insert_from_gap (ptrdiff_t nchars, ptrdiff_t nbytes, bool text_at_gap_tail)
      of this dance.  */
   invalidate_buffer_caches (current_buffer, GPT, GPT);
   record_insert (GPT, nchars);
-  MODIFF++;
+  modiff_incr (&MODIFF);
 
   GAP_SIZE -= nbytes;
   if (! text_at_gap_tail)
@@ -1228,7 +1228,7 @@ insert_from_buffer_1 (struct buffer *buf,
 #endif
 
   record_insert (PT, nchars);
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 
   GAP_SIZE -= outgoing_nbytes;
@@ -1329,7 +1329,7 @@ adjust_after_replace (ptrdiff_t from, ptrdiff_t from_byte,
 
   if (len == 0)
     evaporate_overlays (from);
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 }
 
@@ -1524,7 +1524,7 @@ replace_range (ptrdiff_t from, ptrdiff_t to, Lisp_Object new,
 
   check_markers ();
 
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 
   if (adjust_match_data)
@@ -1655,7 +1655,7 @@ replace_range_2 (ptrdiff_t from, ptrdiff_t from_byte,
 
   check_markers ();
 
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 }
 
@@ -1830,7 +1830,7 @@ del_range_2 (ptrdiff_t from, ptrdiff_t from_byte,
      at the end of the text before the gap.  */
   adjust_markers_for_delete (from, from_byte, to, to_byte);
 
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 
   /* Relocate point as if it were a marker.  */
@@ -1884,7 +1884,7 @@ modify_text (ptrdiff_t start, ptrdiff_t end)
   BUF_COMPUTE_UNCHANGED (current_buffer, start - 1, end);
   if (MODIFF <= SAVE_MODIFF)
     record_first_change ();
-  MODIFF++;
+  modiff_incr (&MODIFF);
   CHARS_MODIFF = MODIFF;
 
   bset_point_before_scroll (current_buffer, Qnil);