* [PATCH] Handle first change undo marker correctly at decode_coding@coding.c
@ 2012-06-21 19:34 Gergely Risko
0 siblings, 0 replies; only message in thread
From: Gergely Risko @ 2012-06-21 19:34 UTC (permalink / raw)
To: emacs-devel
[-- Attachment #1: Type: text/plain, Size: 1325 bytes --]
Hi,
I've run into the following problem the other day:
-=-
(defun common ()
(save-buffer)
(setq buffer-undo-list nil))
(defun insert-bad ()
(interactive)
(common)
(insert-file-contents "/etc/fstab"))
(defun insert-good ()
(interactive)
(common)
(insert "foobar"))
-=-
If I open a file and run insert-good and then I undo, the file goes back
to unmodified state.
If I open a file and run insert-bad and then I undo, the file doesn't
go back to unmodified state.
Investigating, it turned out that if insert-file-contents is ran for
an unmodified buffer, the first change marker of (t HIGH . LOW) is not
inserted although it should've been.
This is because of a bug in decode_coding@coding.c, where by the time
the record_insert is ran at the end, MODIFF is already too high.
MODIFF gets increased in insert_from_gap (used by produce_chars). But
at the point of increase there is a record_insert before:
-=-
record_insert (GPT, nchars);
MODIFF++;
-=-
So why it's not having the effect of recording first change? Because
decode_coding disables undo list handling at the beginning of the
function. Therefore, my solution is to record the first change (if
MODIFF <= SAVE_MODIFF) before the undo list handling gets disabled.
I attached the patch, please consider applying it.
Thanks,
Gergely Risko
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: emacs-coding-insert.patch --]
[-- Type: text/x-diff, Size: 788 bytes --]
diff --git a/src/coding.c b/src/coding.c
index eb89563..212e73e 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -7083,6 +7083,15 @@ decode_coding (struct coding_system *coding)
set_buffer_internal (XBUFFER (coding->dst_object));
if (GPT != PT)
move_gap_both (PT, PT_BYTE);
+
+ /* We have to disable undo_list, so we can record the whole
+ insert transaction via record_insert at the end.
+ Unfortunately, disabling the undo recording also disables the
+ recording of the first change in the undo_list. Therefore
+ we check for first change here and record it via
+ record_first_change if needed. */
+ if (MODIFF <= SAVE_MODIFF)
+ record_first_change ();
undo_list = BVAR (current_buffer, undo_list);
BVAR (current_buffer, undo_list) = Qt;
}
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2012-06-21 19:34 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-06-21 19:34 [PATCH] Handle first change undo marker correctly at decode_coding@coding.c Gergely Risko
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).