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, 2 insertions, 2 deletions

diff --git a/src/fileio.c b/src/fileio.c
index aececcda305..55c9f26b753 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4618,7 +4618,7 @@ by calling `format-decode', which see.  */)
           ptrdiff_t opoint = PT;
           ptrdiff_t opoint_byte = PT_BYTE;
           ptrdiff_t oinserted = ZV - BEGV;
-          EMACS_INT ochars_modiff = CHARS_MODIFF;
+          modiff_count ochars_modiff = CHARS_MODIFF;
 
           TEMP_SET_PT_BOTH (BEGV, BEGV_BYTE);
           insval = call3 (Qformat_decode,
@@ -4658,7 +4658,7 @@ by calling `format-decode', which see.  */)
               ptrdiff_t opoint = PT;
               ptrdiff_t opoint_byte = PT_BYTE;
               ptrdiff_t oinserted = ZV - BEGV;
-              EMACS_INT ochars_modiff = CHARS_MODIFF;
+              modiff_count ochars_modiff = CHARS_MODIFF;
 
               TEMP_SET_PT_BOTH (BEGV, BEGV_BYTE);
               insval = call1 (XCAR (p), make_fixnum (oinserted));