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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 1523AC4363D for ; Fri, 2 Oct 2020 09:45:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C59CD206DD for ; Fri, 2 Oct 2020 09:45:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="huOhoB0L" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387684AbgJBJpm (ORCPT ); Fri, 2 Oct 2020 05:45:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725993AbgJBJpm (ORCPT ); Fri, 2 Oct 2020 05:45:42 -0400 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C876AC0613D0; Fri, 2 Oct 2020 02:45:41 -0700 (PDT) Received: by mail-wr1-x444.google.com with SMTP id e16so1080913wrm.2; Fri, 02 Oct 2020 02:45:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=G+ywyTrniNZc042b3yFhIv1wH4T4KbyH6D7/fYEWnm4=; b=huOhoB0LPDThNLhet2hZWwxkYPyamZ2oLoUpPofklfEPhAHFBUbupGV+DJGdXpEzhs 1yk7J1zpfYvjdDdO22cF0SGhGW70w/bZO0ewGHJLXpfIZMM5ODQAGw9yVWeclU4ngEfL E+l4EPOMmhaxUHjAOTMdt1Ru2K9AahdGihGmM4BO5KhXAQXz4QebcMAODaNCK/Yf5DK7 N+BMrEscNkNGBLkupXinOdXEQpYuU/YOXBP8tjEg0lG8ksSc65zW4VepQHu+cKNyK9Fp whhrGKtIle7sCWc59jLcCeh7/EiQeKherPOBR0d2zZKby6JbVcxtOWP3rz9xy7L/mb28 KTsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=G+ywyTrniNZc042b3yFhIv1wH4T4KbyH6D7/fYEWnm4=; b=BTjZ+3WtgJHaClXSq7S82Q9Zh1LPyLSSs/NoEHn8nS4ByiseFwRz2wOy48U3NYrreX alhTSsa7PWctmlO6DptahQdAw94Tvuqst0xc9woF36IFsg7L+z1eyKK7txAo2hJtRVqr Yk5ROFBjY2dtNUFxact7UXjQgPLcwwH94srsj9NnbbYGt5OijJnNK4Vsm2i/ZLrf3tHF fOecJ5K+knkTWSEiU+bQG6lkQnSyUGptpci04HUQ/Jx2ZzUEm6PKLjNiGSlsvgDJrDfB ebwihtcHmTL8Z0molHNJmo/t5m5uDtL6mtqZhRvn6k1fx37vDrcCRR6u0cmn8un0f1E4 nsUQ== X-Gm-Message-State: AOAM531HbpBnoOyFQsPFSb89uful3HIjxi7ovB0VjowH7phOd0dBy3gn aSS5hgknu+hAgHYUubNdpy0= X-Google-Smtp-Source: ABdhPJzXe8k6dcR3DjnkMU9AMtiAvQ/kGURK1+JsLr3OZy4mgplWhp+Uw8QP4e9vxeRF6bXACNIV2A== X-Received: by 2002:adf:ef4a:: with SMTP id c10mr1950027wrp.13.1601631940551; Fri, 02 Oct 2020 02:45:40 -0700 (PDT) Received: from localhost.localdomain ([170.253.60.68]) by smtp.googlemail.com with ESMTPSA id x17sm1210985wrg.57.2020.10.02.02.45.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Oct 2020 02:45:40 -0700 (PDT) From: Alejandro Colomar To: mtk.manpages@gmail.com, eggert@cs.ucla.edu, David.Laight@ACULAB.COM Cc: Alejandro Colomar , linux-man@vger.kernel.org, gcc-patches@gcc.gnu.org, libc-alpha@sourceware.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] system_data_types.7: void *: Add info about pointer artihmetic Date: Fri, 2 Oct 2020 11:44:52 +0200 Message-Id: <20201002094451.17997-1-colomar.6.4.3@gmail.com> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Reported-by: Paul Eggert Reported-by: David Laight Signed-off-by: Alejandro Colomar --- Paul and David, Thanks for your input! Alex man7/system_data_types.7 | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/man7/system_data_types.7 b/man7/system_data_types.7 index 6451782db..bc7d5a8a0 100644 --- a/man7/system_data_types.7 +++ b/man7/system_data_types.7 @@ -1918,6 +1918,17 @@ A value of this type can't be dereferenced, as it would give a value of type .I void which is not possible. +Likewise, pointer arithmetic is not possible with this type. +However, in GNU C, poitner arithmetic is allowed +as an extension to the standard; +this is done by treating the size of a +.I void +or of a function as 1. +A consequence of this is that +.I sizeof +is also allowed on +.I void +and on function types, and returns 1. .PP The conversion specifier for .I void * -- 2.28.0