From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49783C433FF for ; Mon, 29 Jul 2019 12:24:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E8F1217F4 for ; Mon, 29 Jul 2019 12:24:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="Hc9DVUB9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726255AbfG2MYA (ORCPT ); Mon, 29 Jul 2019 08:24:00 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:32963 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726738AbfG2MYA (ORCPT ); Mon, 29 Jul 2019 08:24:00 -0400 Received: by mail-qk1-f194.google.com with SMTP id r6so43961901qkc.0 for ; Mon, 29 Jul 2019 05:23:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=h93KMWTgMZDnkWWP8nidzTcTTS/K0DE/79C+3LGxZF0=; b=Hc9DVUB9zGGrVJ8J2XEA+M4C3aZJx9c49dmpHKzoNCU2ejgaEqSxcv3fhGVhL+uzWw nHL4gBKdAutOpH1vaKc1M6+W0ck2WmO/L3JPOdrvghzNnafLHj6ur1wKr7AhxxFvvPuO 6KxorB8bmMspaipmAq0EUj8Du3vfHbwgnUGzgFQHhAd3dK0QvoB12hNRn/RBdV0hltUZ 3WuVf+t2D413Q+eztp06HMs3MEBWx3stoWCezwzdZJWPXNxgeD+Mkpgk2XvXR1mxBzzS +m4M/kIRbiIDW/AKv6ZwMZxdHrWUx0B4rAj66mKfJRrJ1kwrOvJ+8dWdCUCWjDy9t6bG SVHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=h93KMWTgMZDnkWWP8nidzTcTTS/K0DE/79C+3LGxZF0=; b=A4MpRC/UEBQ0rC1ct9XyYRSd8YGt/ONLvW2rUMHELOu8MmIWJ046SO+YIiOqpZzGeo O2rinnLsSBxjrzgv9WmE+NVQvVfPAU/nRPtPxSvufe3JQKRDPpKrr09ZZ9IA9N2BUjnk 75BEvRAFZZlvx248pnNDrZIL6eBRDqKQuwrWuyNdKNWAzhDCMF/rkf3x6BJK6Nfr5DZY t1j/8eunbQ7Az1rg/hWmHu0bub5gcuXneVJoz9P2f5Bvj5xiVcYin20P/ogrn9HXysLK +qIfQPP5+dtVgjplhsMRZoa/mKu6Qzg1yUczZvnhJLKeVRpoZLGjWdnSMQhDFPG1aPnf Fh0Q== X-Gm-Message-State: APjAAAWiH3zHHgICzPUpf6+z2d7Tnwtbxr3C5gaJfKhNbe7EWXh/axPV fj6rymnc/nkt8QErBx7cgICYug== X-Google-Smtp-Source: APXvYqxrPcU1gM141pqbYW+SSfFaWlhOugMMiTXWccTr698mw4+8vnReZ5XSKCVN6p63tuF/+YFJfQ== X-Received: by 2002:a37:4a8a:: with SMTP id x132mr74044881qka.42.1564403038878; Mon, 29 Jul 2019 05:23:58 -0700 (PDT) Received: from [192.168.1.153] (pool-71-184-117-43.bstnma.fios.verizon.net. [71.184.117.43]) by smtp.gmail.com with ESMTPSA id 2sm32890868qtz.73.2019.07.29.05.23.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Jul 2019 05:23:58 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Subject: Re: [PATCH v2] acpica: fix -Wnull-pointer-arithmetic warnings From: Qian Cai In-Reply-To: Date: Mon, 29 Jul 2019 08:23:57 -0400 Cc: "Moore, Robert" , "Wysocki, Rafael J" , "Schmauss, Erik" , "jkim@FreeBSD.org" , "lenb@kernel.org" , "ndesaulniers@google.com" , "linux-acpi@vger.kernel.org" , "devel@acpica.org" , "clang-built-linux@googlegroups.com" , "linux-kernel@vger.kernel.org" Content-Transfer-Encoding: quoted-printable Message-Id: <7667BD59-E9FF-4374-AEF6-025FD13837B6@lca.pw> References: <20190718194846.1880-1-cai@lca.pw> <94F2FBAB4432B54E8AACC7DFDE6C92E3B9661CBD@ORSMSX110.amr.corp.intel.com> To: David Laight X-Mailer: Apple Mail (2.3445.104.11) Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org > On Jul 29, 2019, at 6:24 AM, David Laight = wrote: >=20 > From: Moore, Robert >> Sent: 26 July 2019 20:36 > ... >> This is because pointer arithmetic >> on a pointer not pointing to an array is an undefined behavior (C11 = 6.5.6, constraint 8). > ... >=20 > The standards committee as smoking dope again :-) > If that is enforced as a compiler warning/error a lot of code = 'breaks'. > Anything that does: > struct foo *foo =3D ...; > struct bar *bar =3D (void *)(foo + 1); > suddenly becomes 'invalid=E2=80=99. The clang will generate a warning only if =E2=80=9Cfoo" is NULL.