From owner-sc22wg14+sc22wg14-domo2=www.open-std.org@open-std.org Thu Aug 20 20:25:19 2026 Return-Path: X-Original-To: sc22wg14-domo2 Delivered-To: sc22wg14-domo2@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id 6A11B356E01; Thu, 20 Aug 2026 20:25:19 +0200 (CEST) Delivered-To: sc22wg14@open-std.org Received: from mail-ot1-f44.google.com (mail-ot1-f44.google.com [209.85.210.44]) by www.open-std.org (Postfix) with ESMTP id 0B61E356AED for ; Thu, 20 Aug 2026 20:25:18 +0200 (CEST) Received: by mail-ot1-f44.google.com with SMTP id 46e09a7af769-7eb61bbeb25so150276a34.1 for ; Thu, 20 Aug 2026 11:25:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aaronballman.com; s=google; t=1787250318; x=1787855118; darn=open-std.org; h=content-type:to:subject:message-id:date:from:mime-version:from:to :cc:subject:date:message-id:reply-to:content-type; bh=OuuXVHy3b3Cy/4KvRlDisjaXAnacApOYiZ1k+JLRb4g=; b=wfSjIgPwqLmL6krPecma1OVD3+BPGwbc8V5KmH9n6TyLlLCJMws1R7+9J/8N+UWspM BEohzNhZuFooSxiTolHKciFR01TF8Lwwzk6X+9BM2lxlNpssH4MQ9WPtN6uoOKUI4NG+ 5tRL/ECd2tOpnT3TH5F/9ZMoNc3wj0ypg9SsNeA8/aYwYobCsXfHoy4EgTrrLpSEHbc+ 4FmDFLO9XzrW1adjI2FdwxTcrtNU52JM/0VNFXRRQOR9NW9D5uOfQFgobjfXGOxOnrWF WADqqR1Q4JbLa3H+cOOII99K7RCxAshmwAFw6Kiu3XmBqglfD7w5MPm8iyVMp0JWz7Pk GrWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787250318; x=1787855118; h=content-type:to:subject:message-id:date:from:mime-version:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=OuuXVHy3b3Cy/4KvRlDisjaXAnacApOYiZ1k+JLRb4g=; b=PG5fHA6Oh+csTXEJb/npJqYg4wHixiY3rRBm0tvptL8KFXc+W8Zs7iOP4YzBylR9Ri t2ulmI5JatEW3TE66JdiicHcpKdra5qtosN9wHdkKiMtmJo7L0+NdLYrQhxokeSYwZSF QSt+8p1WUZLxFbxaXDNfrd3AwEVJTISwJgR65MnI2j+t1mUzixzjzCJAWXqUi9mpIlgO 4D5wdZHEAWpQopdAhvh6SdnS22vAacDix1MycSG/aqkP5QBl5if32rDbc2lDkC5Mz4c8 pk9foOmQhlJyeO/yOa1bwqOlzi3UfG8bxs2MXCYuivDoCwY4YSXn7cu4AHcB9AJ0GE+x MtmQ== X-Gm-Message-State: AOJu0Yy7UT4updJbikPMsTKlhLt10SSG5+2Vvoc86fQq7iYKGCoimQUk 1mrF9AL61/aSG+TumzhxsPEKuHwWM77Lx/n2Vs0+hCKsYcD9jo1Mr/5KoWujgXu9vLRY/SSHYBg 7c41w X-Gm-Gg: AR+sD118YO4berl1uxbVbuVu/75hfVvDKJT4UAQwmlZMkI00pmCA+ipomZfe3H/x3Ui U5dkgeXaXrQs49OiLoeEBrQHzvcEocBCf9bEbWzjvNofeFedNVjMDxPGAT34xQJOvISZ0gP39/B BRDw6F+WD+2vEx1puAcAHDfauQK5a/h+XsgYbA+c6g6p82SLnfUuYf7VIE1Jlfzl6JtMOqbwSxP nIaW+QcYH1Now1kTDCDl+JamfuFPGDt788ASVn4SBIRT2Tu9OXN0mPOMdgAG0+xrScEW3zPZMJj sbaOl+ffzbnx6zot2tYWpHIf69LbvRtY53VFedp+eHy+4wDhefLonKrsS/iyv0btEUGMNKOEsJC QPc0Ior7oR0iYd12Kc6JFbc8vKSsE70jVG60/oEwl0OQO2xsMdIkePg62m9eZhyHzYK1meVVTI9 uUQJQMjQQqpoIuOBpo4J3pc/qPMfC4XBeJW4uQiJN6WqqF5T8cuF+PSrAyQ4YF+iqvXJVS/7eou FyuZUA6dUZ8heWnhZX7fC2eq6wm X-Received: by 2002:a05:6830:838d:b0:7e9:c76c:abe3 with SMTP id 46e09a7af769-7f461319e65mr561570a34.6.1787250317509; Thu, 20 Aug 2026 11:25:17 -0700 (PDT) Received: from mail-oo1-f52.google.com (mail-oo1-f52.google.com. [209.85.161.52]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7f440056f5dsm5440565a34.23.2026.08.20.11.25.16 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Aug 2026 11:25:16 -0700 (PDT) Received: by mail-oo1-f52.google.com with SMTP id 006d021491bc7-6b153aa3e5fso170944eaf.1 for ; Thu, 20 Aug 2026 11:25:16 -0700 (PDT) X-Received: by 2002:a05:6820:a34d:b0:6ac:b6c0:2c09 with SMTP id 006d021491bc7-6b1591d99c1mr578227eaf.1.1787250315657; Thu, 20 Aug 2026 11:25:15 -0700 (PDT) MIME-Version: 1.0 From: Aaron Ballman Date: Thu, 20 Aug 2026 14:25:02 -0400 X-Gmail-Original-Message-ID: X-Gm-Features: AcwNN1XpiIKI0oNWh7hr2dNmBL5xnitRQ7oALDZRNcquVxB8X3GgKDKnDcoeob0 Message-ID: Subject: Investigation of Issue 1022 To: wg14 Content-Type: text/plain; charset="UTF-8" Sender: owner-sc22wg14@open-std.org Precedence: bulk Here's my responses to questions in the issue (no answer for Q4 or Q8): Q1: The construct is accepted by Clang, GCC, SDCC, cc65, chibicc, edg, ORCA/C, tendra, TCC, and CompCert; it is rejected by MSVC and norcroft. Q2: I hope it's not an lvalue. Q3: UB when the pointer value is invalid but what about questions around alignment? Also, if it's a pointer to a volatile void, are there memory accesses required or not? Q5: the construct is accepted by Clang, GCC, SDCC, cc65, chibicc, edg, ORCA/C, and TCC; it is rejected by MSVC, norcroft, tendra, and CompCert. Q6: not every compiler that accepts the declaration accepts the use of the variable (ORCA/C). Q7: I think the answer should be the same as for Q2. Q9: I don't think we should make qualified void be special compared to void because the original goal that spawned this issue was type generic metaprogramming, however, what does it *mean* to do: volatile void *vp; *vp; ? Is there a memory access there which cannot be reordered? ~Aaron