From: Andreas Schwab <schwab@linux-m68k.org>
To: Lars Ingebrigtsen <larsi@gnus.org>
Cc: Andy Gaynor <goldipox@mail.com>,
54501@debbugs.gnu.org, Stefan Monnier <monnier@iro.umontreal.ca>
Subject: bug#54501: Segfault on recursive structure
Date: Tue, 22 Mar 2022 16:02:57 +0100 [thread overview]
Message-ID: <87y212do7y.fsf@igel.home> (raw)
In-Reply-To: <87cziekpwk.fsf@gnus.org> (Lars Ingebrigtsen's message of "Tue, 22 Mar 2022 15:44:43 +0100")
On Mär 22 2022, Lars Ingebrigtsen wrote:
> So this bug report is about two things. The first is that this reads to
> (nil):
>
> #0=#0#
>
> Which seems odd. Reading #0=#1# signals an error, but it's not
> immediately clear to me whether #0=#0# is totally nonsensical or not.
> And if not, is (nil) the right result? Anybody?
That's an side effect of the implementation: (nil) is the placeholder
object which #0# then references.
> The other thing is more serious, and reading the following will segfault
> your Emacs, so don't do that:
>
> #0=[#1=(#0# . #1#)]
>
> Now, Emacs segfaults on trying to gc a number of recursive objects
> (especially ones that recurse in the `car'), but this seems to actually
> segfault in the reader. Is it obvious to anybody why?
Does it crash in substitute_object_recurse?
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
next prev parent reply other threads:[~2022-03-22 15:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-21 14:26 bug#54501: 27.2; to be disclosed in private Andy Gaynor
2022-03-22 14:44 ` bug#54501: Segfault on recursive structure Lars Ingebrigtsen
2022-03-22 15:02 ` Andreas Schwab [this message]
2022-03-22 15:04 ` Lars Ingebrigtsen
[not found] ` <trinity-1bb5c502-bafe-4a6c-b6be-08a2a1b27232-1648049044877@3c-app-mailcom-lxa04>
2022-03-25 15:34 ` Lars Ingebrigtsen
2022-03-26 15:58 ` Mattias Engdegård
2022-03-26 16:33 ` Lars Ingebrigtsen
[not found] ` <8F7060F3-8137-4835-873F-68E3F6B8010D@acm.org>
2022-03-26 17:43 ` Mattias Engdegård
2022-03-26 18:00 ` Eli Zaretskii
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