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From: Paul Eggert <eggert@cs.ucla.edu>
To: "Eli Zaretskii" <eliz@gnu.org>,
	"Gerd Möllmann" <gerd.moellmann@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: Question regarding Lisp_Object representation of symbols
Date: Wed, 6 Mar 2024 12:32:35 -0800	[thread overview]
Message-ID: <b8345f3d-a227-475b-be35-ad3c4e46e3f3@cs.ucla.edu> (raw)
In-Reply-To: <8634t3lfq7.fsf@gnu.org>

On 2024-03-06 04:14, Eli Zaretskii wrote:
>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>>
>> - Does someone remember the reasons why this has been done?

Speed. It's significantly more efficient.


>> - Is there something that relies on this? Maybe something that
>>    relies on 0x0 being a valid Lisp_Object?

Yes, these assumptions are present in other places. I tried to mark all 
these places with "verify (NIL_IS_ZERO)" a decade ago, though I wouldn't 
be surprised if I missed one or two at the time, or if other 
dependencies have crept in since then (notably in src/comp.c, which I 
haven't audited for this).



  reply	other threads:[~2024-03-06 20:32 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-06  6:48 Question regarding Lisp_Object representation of symbols Gerd Möllmann
2024-03-06  8:41 ` Po Lu
2024-03-06  8:56   ` Gerd Möllmann
2024-03-06 12:14 ` Eli Zaretskii
2024-03-06 20:32   ` Paul Eggert [this message]
2024-03-07  4:28     ` Gerd Möllmann

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