From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Troy Hinckley Newsgroups: gmane.emacs.devel Subject: question about Qnil representation Date: Wed, 26 Oct 2022 09:40:30 -0600 Message-ID: <5a00e93e-5f44-4865-aeeb-51f0aced9996@Spark> References: <5a560265-fa81-42d2-945b-ab85d72df9e6@Spark> Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="635954f3_4db127f8_10bc8" Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="32493"; mail-complaints-to="usenet@ciao.gmane.io" To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Oct 26 17:41:44 2022 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oniXH-0008Cg-LG for ged-emacs-devel@m.gmane-mx.org; Wed, 26 Oct 2022 17:41:43 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oniWJ-00081G-LE; Wed, 26 Oct 2022 11:40:43 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oniWI-0007hp-25 for emacs-devel@gnu.org; Wed, 26 Oct 2022 11:40:42 -0400 Original-Received: from mail-il1-x12f.google.com ([2607:f8b0:4864:20::12f]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1oniWG-0007iU-4L for emacs-devel@gnu.org; Wed, 26 Oct 2022 11:40:41 -0400 Original-Received: by mail-il1-x12f.google.com with SMTP id g13so9019961ile.0 for ; Wed, 26 Oct 2022 08:40:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:subject:references:in-reply-to:message-id:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=twVPFuYncy7AQMRmgyCrBTfVDWp5oqcuJTj42xFmCuE=; b=A6Ek0GFOcDmKYbQBSNRkGD3RII1UETB1z8SNE9mP0LHI91VrVBzbL00T3vYJAW273p 7GrgEIlGQNB/uIYvT6sE0hhmU7CoBtDE7fM+3azeVEP8WvT3mdgQplTwO+xjywjRuJ3w JYFdolTfal8Ir0Gc5DCksoCN9j05c1P+t6cZJvChZJcmSpEXxam4a8nikRaSCwULJ0k+ 5qrA19f0zhtHjtGSQH6R2hhmvRpQkw+b7mS7W+kRQ3AffC2Izdubqkq9kn+cflNDvetM jYc60uNEeSOO6YWF2vnNOG5+GxACdNPdrwBOr+dMZKKSb67fcJaow4b2M3C5Mdk1JS1l 2sxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:subject:references:in-reply-to:message-id:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=twVPFuYncy7AQMRmgyCrBTfVDWp5oqcuJTj42xFmCuE=; b=civ/p0Qxlrw4tJsmcol9tgN+Xk+0WUYAhd98CP7UZr9eQa9zhlynHMFIW+9ZNVolJS 9BSdKBaWqTCc1vnvkyaOxZyzIV5nEb1ruaxw34q8Ze10cMjyAXQ6RpsGPALqX0nlvnnR LLVsPwy1UWPNmn/FcxoFCfiY09jzTy5loydC42/hq9I/+z90zzKJehRXrkI7MvLo83u0 /cOnZ0QGpBZGacv1z22BuZcqOtdLQ3GgUXZ24Dy9GRjWAkVDlSmBs1dNGWqBKVrDDy5M zjcutzplewKJmG9U03s8/OPaPSOeY48tSm2mHAmBH6sdzskggZ4+ewP54Gcs7tXd7ztg sv0Q== X-Gm-Message-State: ACrzQf1wfw/gH+3usmlOXiQYMKCeujySNRpcsrjlnJjPBSuMZZL9hakT ePvcaU4z6rgeQqIJW7Fu9AlpbV7MFm4= X-Google-Smtp-Source: AMsMyM6XidYIPlENINfUIac/1kG+hOg/vmkrHBZHKiUN3KcSD8QZxnL4lg2Og89uzxotwZg+x40yEQ== X-Received: by 2002:a05:6e02:174b:b0:300:5dbf:5568 with SMTP id y11-20020a056e02174b00b003005dbf5568mr1785367ill.214.1666798837528; Wed, 26 Oct 2022 08:40:37 -0700 (PDT) Original-Received: from [192.168.1.121] (h24-54-181-16.ftcmco.broadband.dynamic.tds.net. [24.54.181.16]) by smtp.gmail.com with ESMTPSA id m40-20020a026a68000000b00363ac6a0b89sm2093728jaf.172.2022.10.26.08.40.36 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Oct 2022 08:40:37 -0700 (PDT) In-Reply-To: <5a560265-fa81-42d2-945b-ab85d72df9e6@Spark> X-Readdle-Message-ID: 5a00e93e-5f44-4865-aeeb-51f0aced9996@Spark Received-SPF: pass client-ip=2607:f8b0:4864:20::12f; envelope-from=troyhinckley@gmail.com; helo=mail-il1-x12f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: "Emacs-devel" Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:298554 Archived-At: --635954f3_4db127f8_10bc8 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline I have been reading through the C source to try and learn it and understa= nd it better. I saw in Changeling.13 an entry =46rom Paul Eggert on 2015-= 01-05 with =E2=80=9CUse 0 for Qnil=E2=80=9D As a fix for Bug=2315880. How= does this work in practice=3F It looks like symbols are just pointers, b= ut 0 would not be a valid pointer. I don=E2=80=99t see any special code f= or handling the null case. --635954f3_4db127f8_10bc8 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
I have been reading through the C source to try and= learn it and understand it better. I saw in Changeling.13 an entry =46ro= m Paul Eggert on 2015-01-05 with =E2=80=9CUse 0 for Qnil=E2=80=9D As a fi= x for Bug=2315880. How does this work in practice=3F It looks like symbol= s are just pointers, but 0 would not be a valid pointer. I don=E2=80=99t = see any special code for handling the null case.&=23160;
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