From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS22989 209.51.188.0/24 X-Spam-Status: No, score=-4.1 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H2, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.6 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 6EA361F47C for ; Mon, 16 Jan 2023 00:15:28 +0000 (UTC) Authentication-Results: dcvr.yhbt.net; dkim=pass (1024-bit key; unprotected) header.d=cs.ucla.edu header.i=@cs.ucla.edu header.a=rsa-sha256 header.s=78364E5A-2AF3-11ED-87FA-8298ECA2D365 header.b=I3ryB1vd; dkim-atps=neutral Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pHD9e-0000wj-Ap; Sun, 15 Jan 2023 19:15:14 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pHD9b-0000wM-3X for bug-gnulib@gnu.org; Sun, 15 Jan 2023 19:15:11 -0500 Received: from zimbra.cs.ucla.edu ([131.179.128.68]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pHD9Y-0002Hl-JV for bug-gnulib@gnu.org; Sun, 15 Jan 2023 19:15:10 -0500 Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 005D2160041; Sun, 15 Jan 2023 16:15:05 -0800 (PST) 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 LTn5xU0aO8PH; Sun, 15 Jan 2023 16:15:05 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 2CF57160044; Sun, 15 Jan 2023 16:15:05 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.9.2 zimbra.cs.ucla.edu 2CF57160044 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cs.ucla.edu; s=78364E5A-2AF3-11ED-87FA-8298ECA2D365; t=1673828105; bh=CQQ+h9++R0tC7mocHcYJK1qK4aNHMaI207KeTVsIHko=; h=Message-ID:Date:MIME-Version:To:From:Subject:Content-Type: Content-Transfer-Encoding; b=I3ryB1vdxjin4aFh3ERhOMzo0ozlH9U8O9ujPEFvpjowfJLBzZiOq7SOM0A2fxG+p 8IgevvQl5VljU4jF6Fmpc+Ofu1WfrHT9utNSKTOPWn1sPuGYhyxFZob+aRJf0ZnNVq xNdmz7imvtNUYbhGKjYtZlxNCv1gsfCaA/qIF6u8= 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 hCCxHmygq2qA; Sun, 15 Jan 2023 16:15:05 -0800 (PST) Received: from [192.168.1.9] (cpe-172-91-119-151.socal.res.rr.com [172.91.119.151]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id F0BED160041; Sun, 15 Jan 2023 16:15:04 -0800 (PST) Message-ID: <3809858c-bc89-5bce-2c9c-747272c03f2c@cs.ucla.edu> Date: Sun, 15 Jan 2023 16:15:04 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Content-Language: en-US To: Bruno Haible References: <20230113201704.325290-1-eggert@cs.ucla.edu> <8041574.c9vzh5UkMf@nimes> <2228043.iJkMF17ckq@nimes> From: Paul Eggert Organization: UCLA Computer Science Department Cc: bug-gnulib@gnu.org Subject: Re: [PATCH 1/4] localename: -Wtautological-pointer-compare In-Reply-To: <2228043.iJkMF17ckq@nimes> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=131.179.128.68; envelope-from=eggert@cs.ucla.edu; helo=zimbra.cs.ucla.edu X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: bug-gnulib@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gnulib discussion list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnulib-bounces+normalperson=yhbt.net@gnu.org Sender: bug-gnulib-bounces+normalperson=yhbt.net@gnu.org On 2023-01-15 14:03, Bruno Haible wrote: >> My confusion arose partly because I am accustomed to languages where the >> distinction between null and non-null pointers is checked statically ... > > Oh, now I understand. May I guess the language: Haskell, OCaml, TypeScript, > Rust? These days OCaml and maybe Rust, though the language that first comes to my mind is one I designed in the 1970s and never got off the ground: B Pascal. > Unfortunately, this is an excellent example for a portability problem: > The division yields a SIGFPE on x86, x86_64, alpha, m68k, and s390/s390x > CPU, but not on other architectures. I suppose I should have written that my assumption was that the code is executed in a context where the divisor must be positive. (This is pretty common when calculating indexes from sizes.) In other contexts the extra checking may be necessary, or at least helpful.