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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 0AB54C4363C for ; Fri, 2 Oct 2020 17:00:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D239B20758 for ; Fri, 2 Oct 2020 17:00:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387908AbgJBRAX (ORCPT ); Fri, 2 Oct 2020 13:00:23 -0400 Received: from zimbra.cs.ucla.edu ([131.179.128.68]:48560 "EHLO zimbra.cs.ucla.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387768AbgJBRAW (ORCPT ); Fri, 2 Oct 2020 13:00:22 -0400 X-Greylist: delayed 416 seconds by postgrey-1.27 at vger.kernel.org; Fri, 02 Oct 2020 13:00:22 EDT Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id AC1C6160065; Fri, 2 Oct 2020 10:00:22 -0700 (PDT) Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id CW2rExhnLIrm; Fri, 2 Oct 2020 10:00:22 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id F15661600B2; Fri, 2 Oct 2020 10:00:21 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id a9M36EGALxVz; Fri, 2 Oct 2020 10:00:21 -0700 (PDT) Received: from [192.168.1.9] (cpe-23-243-218-95.socal.res.rr.com [23.243.218.95]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id B5D13160065; Fri, 2 Oct 2020 10:00:21 -0700 (PDT) Subject: Re: [PATCH v2 1/2] system_data_types.7: Add 'void *' To: David Laight , 'Alejandro Colomar' Cc: "mtk.manpages@gmail.com" , "linux-man@vger.kernel.org" , "libc-alpha@sourceware.org" , "gcc@gcc.gnu.org" , "linux-kernel@vger.kernel.org" References: <41affebd-3354-9420-0048-bffd14535e95@gmail.com> <20201001154946.104626-2-colomar.6.4.3@gmail.com> <538b683f-01d2-6148-4f1d-1b293eb5cd6b@cs.ucla.edu> <4b86f6e9-0d8a-f14a-73ce-ebbdc9d9edba@gmail.com> From: Paul Eggert Autocrypt: addr=eggert@cs.ucla.edu; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org On 10/2/20 2:10 AM, David Laight wrote: >> > Also, you should >> > warn that because one can convert from any pointer type to void * and >> > then to any other pointer type, it's a deliberate hole in C's >> > type-checking. >> > That isn't what the C standard says at all. > What is says is that you can cast any data pointer to 'void *' > and then cast it back to the same type. I was talking about compile-time checking; you're talking about run-time behavior. We're both right in our own domains. It is a tricky area, and this suggests that perhaps we shouldn't be trying to document this stuff in a libc/kernel manual.