GNU bug report logs - #28527
unexpected behaviour of char-after if argument is marker that don't point to the current buffer

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

From: Fritz Stelzer <brotzeitmacher <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: unexpected behaviour of char-after if argument is marker that don't
 point to the current buffer
Date: Wed, 20 Sep 2017 15:29:07 +0200

[Message part 1 (text/plain, inline)]

When the argument for char-after is a marker, the function gets bytepos
from the buffer the marker is pointing to by calling marker_byte_position.
But then pos_byte is compared to BEGV_BYTE and ZV_BYTE that use the current
buffer. At the end of the function, pos_byte is passed to FETCH_CHAR, which
also operates on the current buffer.

[Message part 2 (text/html, inline)]

Message #8 received at 28527 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Fritz Stelzer <brotzeitmacher <at> gmail.com>
Cc: 28527 <at> debbugs.gnu.org
Subject: Re: bug#28527: unexpected behaviour of char-after if argument is
 marker that don't point to the current buffer
Date: Wed, 20 Sep 2017 18:51:27 +0300

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> Resent-From: Fritz Stelzer <brotzeitmacher <at> gmail.com>
> Original-Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org>
> Resent-CC: bug-gnu-emacs <at> gnu.org
> Resent-Sender: help-debbugs <at> gnu.org
> From: Fritz Stelzer <brotzeitmacher <at> gmail.com>
> Date: Wed, 20 Sep 2017 15:29:07 +0200
> 
> When the argument for char-after is a marker, the function gets bytepos from the buffer the marker is pointing
> to by calling marker_byte_position. But then pos_byte is compared to BEGV_BYTE and ZV_BYTE that use the
> current buffer. At the end of the function, pos_byte is passed to FETCH_CHAR, which also operates on the
> current buffer.

This is according to the documentation, which explicitly says the
position is looked up in the current buffer.  So this sounds like an
intentional and documented behavior.

Message #11 received at 28527 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: Fritz Stelzer <brotzeitmacher <at> gmail.com>, 28527 <at> debbugs.gnu.org
Subject: Re: bug#28527: unexpected behaviour of char-after if argument is
 marker that don't point to the current buffer
Date: Mon, 11 Nov 2019 04:00:14 +0100

tags 28527 + notabug
close 28527
thanks

Eli Zaretskii <eliz <at> gnu.org> writes:

>> When the argument for char-after is a marker, the function gets bytepos from the buffer the marker is pointing
>> to by calling marker_byte_position. But then pos_byte is compared to BEGV_BYTE and ZV_BYTE that use the
>> current buffer. At the end of the function, pos_byte is passed to FETCH_CHAR, which also operates on the
>> current buffer.
>
> This is according to the documentation, which explicitly says the
> position is looked up in the current buffer.  So this sounds like an
> intentional and documented behavior.

With the above explanation and no other comments within 2 years, I'm
closing this as notabug.

Best regards,
Stefan Kangas

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