GNU bug report logs - #75322
SAFE_ALLOCA assumed to root Lisp_Objects/SSDATA(string)

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Message #140 received at 75322 <at> debbugs.gnu.org (full text, mbox):

From: Gerd Möllmann <gerd.moellmann <at> gmail.com>
To: Pip Cet <pipcet <at> protonmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, Paul Eggert <eggert <at> cs.ucla.edu>,
 75322 <at> debbugs.gnu.org
Subject: Re: bug#75322: SAFE_ALLOCA assumed to root Lisp_Objects/SSDATA(string)
Date: Sun, 05 Jan 2025 12:27:33 +0100

Pip Cet <pipcet <at> protonmail.com> writes:

> However, I don't fully understand which additional protections
> traditional GC offers: is it always unsafe to use an SDATA obtained
> before a GC run after the GC run completes, or is there a more
> complicated set of rules?

There is this, which is used in the byte interpreter, IIRC, as sort of a
workaround for the problem

#ifndef HAVE_MPS
/* Pin a unibyte string in place so that it won't move during GC.  */
void
pin_string (Lisp_Object string)
{

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