From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS22989 209.51.188.0/24 X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, RCVD_IN_DNSWL_HI,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 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 0F8EE1F8C6 for ; Sun, 29 Aug 2021 07:57:15 +0000 (UTC) Received: from localhost ([::1]:60810 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mKFgn-0005Gq-US for normalperson@yhbt.net; Sun, 29 Aug 2021 03:57:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52152) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mKFgi-0005Gh-DX for bug-gnulib@gnu.org; Sun, 29 Aug 2021 03:57:08 -0400 Received: from zimbra.cs.ucla.edu ([131.179.128.68]:43464) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mKFgf-0003p7-N3 for bug-gnulib@gnu.org; Sun, 29 Aug 2021 03:57:07 -0400 Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 78C75160071; Sun, 29 Aug 2021 00:57:04 -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 mkNRnLGhxv5w; Sun, 29 Aug 2021 00:57:03 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 973A3160100; Sun, 29 Aug 2021 00:57:03 -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 XQaG4YN0q-QY; Sun, 29 Aug 2021 00:57:03 -0700 (PDT) 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 672E3160071; Sun, 29 Aug 2021 00:57:03 -0700 (PDT) To: Bruno Haible References: <20210827222756.530247-1-eggert@cs.ucla.edu> <3048976.kXSN5OTJKJ@omega> <22573827.hxa6pUQ8Du@omega> From: Paul Eggert Organization: UCLA Computer Science Department Subject: Re: [PATCH] base32, base64: prefer signed to unsigned integers Message-ID: Date: Sun, 29 Aug 2021 00:57:03 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <22573827.hxa6pUQ8Du@omega> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=131.179.128.68; envelope-from=eggert@cs.ucla.edu; helo=zimbra.cs.ucla.edu X-Spam_score_int: -45 X-Spam_score: -4.6 X-Spam_bar: ---- X-Spam_report: (-4.6 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.437, 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: 2.1.23 Precedence: list List-Id: Gnulib discussion list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bug-gnulib@gnu.org Errors-To: bug-gnulib-bounces+normalperson=yhbt.net@gnu.org Sender: "bug-gnulib" On 8/28/21 7:12 AM, Bruno Haible wrote: > Or maybe the cause is the line >=20 > assume (0 <=3D inlen); >=20 > At the entry point of a public function, it is better to use 'assert' t= han > 'assume', IMO. 'assume' means "feel free to crash or press the red butt= on > if there is an invalid argument". 'assume' was the intent. A negative idx_t arg is an error as serious as=20 an out-of-range index in an array, and so should be undefined behavior.=20 We shouldn't sprinkle 'assert's all over the place for this: it should=20 be something builtin to the compiler and/or runtime system when one=20 enables runtime checking. I put in the 'assume' only to help GCC generate better code (to let it=20 choose unsigned or signed division, whichever it thinks is faster).=20 That's overkill here and the 'assume's are evidently dust magnets so I=20 removed the 'assume's in the patch I recently installed.