GNU bug report logs - #11493
24.0.95; regression: comint-output-filter-functions / ansi-color-process-output

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Roland Winkler" <winkler <at> gnu.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.0.95; regression: comint-output-filter-functions /
	ansi-color-process-output
Date: Wed, 16 May 2012 17:46:50 -0500

Some not so old code that works fine with Emacs 23 is giving me
unexpected trouble with Emacs 24. Essentially, it uses a mode
derived from comint-mode. It sends input via comint-simple-send and
comint-send-input, but it has its own output filters. In Emacs 24,
ansi-color-process-output has been added to the hook
comint-output-filter-functions. This hook is also run by
comint-send-input. ansi-color-process-output references the variable
comint-last-output-start. Upon start-up comint-mode assigns this
variable a marker, but it does not give this marker a useful value.
(Only comint-output-filter assigns a buffer position to
comint-last-output-start.)
ansi-color-process-output checks that comint-last-output-start is
non-nil. But it does not handle the case that comint-last-output-start
holds a marker that does not point anywhere. So this code fails.

comint-last-output-start is an undocumented variable and I have not
fully understood what it is supposed to do. Yet it appears to me
that comint.el and ansi-color.el depend on each other in a too
sophisticated way.


In GNU Emacs 24.0.95.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.20.1)
 of 2012-04-04 on regnitz
Windowing system distributor `The X.Org Foundation', version 11.0.10706000

Message #8 received at 11493 <at> debbugs.gnu.org (full text, mbox):

From: Chong Yidong <cyd <at> gnu.org>
To: "Roland Winkler" <winkler <at> gnu.org>
Cc: 11493 <at> debbugs.gnu.org
Subject: Re: bug#11493: 24.0.95; regression: comint-output-filter-functions /
	ansi-color-process-output
Date: Tue, 29 May 2012 21:47:00 +0800

"Roland Winkler" <winkler <at> gnu.org> writes:

> In Emacs 24, ansi-color-process-output has been added to the hook
> comint-output-filter-functions.

Actually, in Emacs 23, ansi-color-process-output is also added to
comint-output-filter-functions at top-level in ansi-color.el.

> ansi-color-process-output checks that comint-last-output-start is
> non-nil. But it does not handle the case that comint-last-output-start
> holds a marker that does not point anywhere. So this code fails.

This is already fixed in the emacs-24 branch, r107978.  Thanks.

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