GNU bug report logs - #57957
29.0.50; Native compilation hangs on cyclic lists

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Package: emacs;

Reported by: Lars Tveito <larstvei <at> ifi.uio.no>

Date: Tue, 20 Sep 2022 14:28:02 UTC

Severity: normal

Tags: confirmed

Merged with 67883, 69872

Found in versions 29.0.50, 29.1.90, 29.2

Done: Andrea Corallo <acorallo <at> gnu.org>

Bug is archived. No further changes may be made.

Full log

Message #31 received at 57957 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Gerd Möllmann <gerd.moellmann <at> gmail.com>
Cc: Lars Ingebrigtsen <larsi <at> gnus.org>, Lars Tveito <larstvei <at> ifi.uio.no>,
 57957 <at> debbugs.gnu.org, Andrea Corallo <akrl <at> sdf.org>
Subject: Re: bug#57957: 29.0.50; Native compilation hangs on cyclic lists
Date: Thu, 22 Sep 2022 13:10:09 -0400

> The question is of course also how much effort circular lists deserve in
> the compiler.  From my point of view, not too much because they aren't
> very useful, in code at least.  And dealing with them costs runtime.

Circular data structures are perfectly normal in source code under
a `quote` but the code itself should never be cyclic (so I think it
would be OK to signal an error (and/or to inf-loop) when asked to
compile a chunk of code that has a cycle).  So we *should* handle
circular data structures correctly.

Note: I don't know why we'd need/want to do a `subst-if` inside
a `quote` and haven't looked at this bug or at the `comp.el` code to
know what we're really talking about.


        Stefan
This bug report was last modified 1 year and 50 days ago.

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