GNU bug report logs - #18555
24.4.50; butlast and nbutlast doesn't handle improper lists

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Package: emacs;

Reported by: Leo Liu <sdl.web <at> gmail.com>

Date: Thu, 25 Sep 2014 04:07:02 UTC

Severity: minor

Tags: notabug, wontfix

Found in version 24.4.50

Done: Stefan Kangas <stefan <at> marxist.se>

Bug is archived. No further changes may be made.

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Report forwarded to bug-gnu-emacs <at> gnu.org:
bug#18555; Package emacs. (Thu, 25 Sep 2014 04:07:02 GMT) Full text and rfc822 format available.
Acknowledgement sent to Leo Liu <sdl.web <at> gmail.com>:
New bug report received and forwarded. Copy sent to bug-gnu-emacs <at> gnu.org. (Thu, 25 Sep 2014 04:07:02 GMT) Full text and rfc822 format available.

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

From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.4.50; butlast and nbutlast doesn't handle improper lists
Date: Thu, 25 Sep 2014 12:05:49 +0800

  (nbutlast '(1 2 . 3))

throws an error due to `length' which can be fixed
by using safe-length instead.

  (butlast '(1 2 . 3))

still throws an error due to copy-sequence not taking
improper list.

What is the right thing to do?

Leo
Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#18555; Package emacs. (Thu, 25 Sep 2014 07:22:02 GMT) Full text and rfc822 format available.

Message #8 received at 18555 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Schwab <schwab <at> suse.de>
To: Leo Liu <sdl.web <at> gmail.com>
Cc: 18555 <at> debbugs.gnu.org
Subject: Re: bug#18555: 24.4.50;
 butlast and nbutlast doesn't handle improper lists
Date: Thu, 25 Sep 2014 09:21:50 +0200

Leo Liu <sdl.web <at> gmail.com> writes:

>   (nbutlast '(1 2 . 3))
>
> throws an error due to `length' which can be fixed
> by using safe-length instead.
>
>   (butlast '(1 2 . 3))
>
> still throws an error due to copy-sequence not taking
> improper list.
>
> What is the right thing to do?

Don't do that then.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab <at> suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#18555; Package emacs. (Mon, 30 Sep 2019 02:40:01 GMT) Full text and rfc822 format available.

Message #11 received at 18555 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: Andreas Schwab <schwab <at> suse.de>
Cc: 18555 <at> debbugs.gnu.org, Leo Liu <sdl.web <at> gmail.com>
Subject: Re: bug#18555: 24.4.50;
 butlast and nbutlast doesn't handle improper lists
Date: Mon, 30 Sep 2019 04:39:27 +0200

tags 18555 + notabug wontfix
close 18555
quit

Andreas Schwab <schwab <at> suse.de> writes:

> Leo Liu <sdl.web <at> gmail.com> writes:
>
>>   (nbutlast '(1 2 . 3))
>>
>> throws an error due to `length' which can be fixed
>> by using safe-length instead.
>>
>>   (butlast '(1 2 . 3))
>>
>> still throws an error due to copy-sequence not taking
>> improper list.
>>
>> What is the right thing to do?
>
> Don't do that then.

Agreed.  Both butlast and nbutlast are documented to work on lists, and
throwing a malformed list at them should correctly signal an error.

I'm therefore closing this bug report.

Best regards,
Stefan Kangas
Added tag(s) wontfix and notabug. Request was from Stefan Kangas <stefan <at> marxist.se> to control <at> debbugs.gnu.org. (Mon, 30 Sep 2019 02:40:02 GMT) Full text and rfc822 format available.
bug closed, send any further explanations to 18555 <at> debbugs.gnu.org and Leo Liu <sdl.web <at> gmail.com> Request was from Stefan Kangas <stefan <at> marxist.se> to control <at> debbugs.gnu.org. (Mon, 30 Sep 2019 02:40:02 GMT) Full text and rfc822 format available.
bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Mon, 28 Oct 2019 11:24:14 GMT) Full text and rfc822 format available.
This bug report was last modified 4 years and 182 days ago.

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