[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#51412: 29.0.50; cl--mapcar-many fails inconsistently in the presence
From: |
Lars Ingebrigtsen |
Subject: |
bug#51412: 29.0.50; cl--mapcar-many fails inconsistently in the presence of circular lists; other shortcomings |
Date: |
Wed, 14 Sep 2022 20:38:45 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
akater <nuclearspace@gmail.com> writes:
> cl--mapcar-many is used as a backend for implementing several cl-
> functions in cl-extra. To deal with arbitrary number of arguments
> (passed to cl--mapcar-many as list cl-seq), it goes through them all
> whenever there are more than 2, in advance, and attempts to compute the
> minimal length.
>
> This fails if any of the arguments is a circular list.
>
> To reproduce, just evaluate (cl-map 'list #'identity '#1=(a . #1#) nil nil).
Debugger entered--Lisp error: (circular-list (a . #2))
> Note that (cl-map 'list #'identity '#1=(a . #1#) nil) doesn't fail so
> this is at the very least inconsistent. N.B.: CL spec says “Should be
> prepared to signal an error” for improper lists for such functions.
> Long story short, this means circular lists can be supported by CL
> implementations according to CL spec.
It's inconsistent, so that should probably be fixed. But isn't
signalling an error here the right thing to do? But I guess as long as
not all the lists are circular, then it's fine to return something
here...
Perhaps Stafan has some comments; added to the CCs.
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- bug#51412: 29.0.50; cl--mapcar-many fails inconsistently in the presence of circular lists; other shortcomings,
Lars Ingebrigtsen <=