From unknown Sat Jun 14 14:25:04 2025 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Mailer: MIME-tools 5.509 (Entity 5.509) Content-Type: text/plain; charset=utf-8 From: bug#41983 <41983@debbugs.gnu.org> To: bug#41983 <41983@debbugs.gnu.org> Subject: Status: Reference Manual: Open Question About Magic Metaness of Vtables Reply-To: bug#41983 <41983@debbugs.gnu.org> Date: Sat, 14 Jun 2025 21:25:04 +0000 retitle 41983 Reference Manual: Open Question About Magic Metaness of Vtabl= es reassign 41983 guile submitter 41983 sebastian.miele@gmail.com severity 41983 normal thanks From debbugs-submit-bounces@debbugs.gnu.org Sun Jun 21 10:27:51 2020 Received: (at submit) by debbugs.gnu.org; 21 Jun 2020 14:27:51 +0000 Received: from localhost ([127.0.0.1]:60721 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jn0wp-0005g7-7G for submit@debbugs.gnu.org; Sun, 21 Jun 2020 10:27:51 -0400 Received: from lists.gnu.org ([209.51.188.17]:53040) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jn0wn-0005fz-Ef for submit@debbugs.gnu.org; Sun, 21 Jun 2020 10:27:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33514) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jn0wn-00060i-6R for bug-guile@gnu.org; Sun, 21 Jun 2020 10:27:49 -0400 Received: from mail-wm1-x329.google.com ([2a00:1450:4864:20::329]:38871) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jn0wl-0007FI-JY for bug-guile@gnu.org; Sun, 21 Jun 2020 10:27:48 -0400 Received: by mail-wm1-x329.google.com with SMTP id f18so801185wml.3 for ; Sun, 21 Jun 2020 07:27:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=user-agent:from:to:subject:reply-to:message-id:date:mime-version; bh=ppV+MfqzHIbp9hzUzbXnV/xqViAcm/C0ch+metSQIX4=; b=nAcfh4OxHaAANZXY+SumJDQG6MBrJyxTAKFPnMX+nnxLt9Y+lQMEUgSYZ6wOStGEtb B3b6K1lTWVnaOf35CmVrTVDMEwh+tdZpLY/9H6NhqzmKxOWESt8vupYY7Z2/BsQfwF6D JnmvLAXROWPdybjrBC40n3ZVFLc7KT56mffp+nQ7T7YVFKe51PsYq8+LwkLc2UHYVD4v QweZx9L3qOPLl05ZIOrqZmMjTTJOFCouVMRNJbvXHFU2em4tXAtqFqyOp69hWK1FQFbg a1X9WExS7RTy74WxezD+Oa3B0xfGU5X8vR4KgsldxeLComenigL93nbJ/D63U7WDok1x drdw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:user-agent:from:to:subject:reply-to:message-id :date:mime-version; bh=ppV+MfqzHIbp9hzUzbXnV/xqViAcm/C0ch+metSQIX4=; b=BdhEqitH7jNZilskGycWWRTSyr+aShuW7Pqv2O4lipzD9XArMuMglC2mXF7JKr+M6/ GEoxtZvpmQZeiveI3RyEwJcDPDfDglrqnLrS/U0ajZmFIro91ymW0zKicNrG/+KwXG/9 OBTDUPW1U6i4g7iXd/60seAbJ2SdE1yGooFQq4jfjptRJNQJwUrlkVC26EcpI4MHycy7 dUQDYZzDsVqvW/dXAXcx42SsQRC2IEyU3bB0ol28Jpoyh9Pzobq/ECPhvrun24/iQZqe 9YIaMjFb5m7D1AKsk9+9DIVu8Rv94rQNt3ttXpFMS0D6jK7GDXcX8V6aVJnrWAen1lYv jauQ== X-Gm-Message-State: AOAM531r50cm06ja3u3gd/vDDMjrCoV2NKsgEAzQACaV+vCForSwtzdz d9kynirxipc8hmuqn447cMK+0HTF X-Google-Smtp-Source: ABdhPJz3PHtipMNstTWc1ltn4gK9wFQ6q/e9PMZ1YKhMOcjq+D4Qk5Wb8bLAMrVLXx41TApZw4ukRQ== X-Received: by 2002:a1c:7206:: with SMTP id n6mr14078525wmc.4.1592749665698; Sun, 21 Jun 2020 07:27:45 -0700 (PDT) Received: from huette ([2a02:908:175c:4260:33a6:b2b0:4ad5:928d]) by smtp.gmail.com with ESMTPSA id e25sm14871891wrc.69.2020.06.21.07.27.44 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Jun 2020 07:27:45 -0700 (PDT) User-agent: mu4e 1.4.10; emacs 26.3 From: Sebastian Miele To: bug-guile@gnu.org Subject: Reference Manual: Open Question About Magic Metaness of Vtables Message-ID: <87eeq8o5nk.fsf@gmail.com> Date: Sun, 21 Jun 2020 16:27:43 +0200 MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=2a00:1450:4864:20::329; envelope-from=sebastian.miele@gmail.com; helo=mail-wm1-x329.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. 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, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-Spam-Score: 0.7 (/) X-Debbugs-Envelope-To: submit X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sebastian.miele@gmail.com Errors-To: debbugs-submit-bounces@debbugs.gnu.org Sender: "Debbugs-submit" X-Spam-Score: -2.3 (--) I am on the current master branch. After reading section 6.6.18.4 (Meta-Vtables) of the reference manual there remains an open question. A structure X made from a meta-vtable becomes a meta-vtable if standard-vtable-fields is a prefix of the layout in X's field 0. And if X is a meta-vtable, every structure with X as a vtable must have a valid layout in field 0. Suppose the following: standard-vtable-fields accidentally is a prefix of some valid layout string l. Then (define v (make-vtable l)) (make-struct/no-tail v 'a) raises an exception, because 'a is not a valid layout. But v may not be intended to be a meta-vtable, just a vtable. The reference manual does mention why that can not happen, or why is it accepted that it may happen.