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=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,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 8E7531F48A for ; Mon, 17 Feb 2020 03:53:38 +0000 (UTC) Received: from localhost ([::1]:39908 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j3XTU-0004xf-Sc for normalperson@yhbt.net; Sun, 16 Feb 2020 22:53:36 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:48885) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j3XTR-0004xS-4T for bug-gnulib@gnu.org; Sun, 16 Feb 2020 22:53:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j3XTP-00060L-Rv for bug-gnulib@gnu.org; Sun, 16 Feb 2020 22:53:32 -0500 Received: from mo6-p00-ob.smtp.rzone.de ([2a01:238:20a:202:5300::8]:22033) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j3XTP-0005wT-7R for bug-gnulib@gnu.org; Sun, 16 Feb 2020 22:53:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1581911607; s=strato-dkim-0002; d=clisp.org; h=References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=uhr/AoUSJK9izi9fGjpz0u31CmECoxIOgT0ZwY+hxWI=; b=ApRVS+5vTTo41fg558U/o2tTQ1OGh2ZtUZqAAbHEKJ/1SQdkMmwCXURvWG0zWfLBQq Oft0xXl89lfZzdGgjvnWkvXQrxaJ16bWCMTSQBRfR1Qtj/tsDyh8gOpnskCrqIhWSl5s 2ECRcpb9jwDRm+sGZOe7+e+UfNDC9Yc8KXqsbrLTP4LG8VNKoTJlQy5/UhQqJVE+9Hyr mYHKYCv+OEMbc9vd8cJMH3r0IrpSYlc178XRRorvUxZJHigfYbAnICKmXKQ3CF1fRCX4 gjJAHYBYwWf9hnTruW7fKRiZ9BiNkViGCnjHyW5cgC2Qkjro3etl2fTw9v0J3WMuezuP MHyg== X-RZG-AUTH: ":Ln4Re0+Ic/6oZXR1YgKryK8brlshOcZlIWs+iCP5vnk6shH+AHjwLuWOH6fzxfs=" X-RZG-CLASS-ID: mo00 Received: from bruno.haible.de by smtp.strato.de (RZmta 46.1.12 DYNA|AUTH) with ESMTPSA id g00701w1H3rEE7Q (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (curve X9_62_prime256v1 with 256 ECDH bits, eq. 3072 bits RSA)) (Client did not present a certificate); Mon, 17 Feb 2020 04:53:14 +0100 (CET) From: Bruno Haible To: Paul Eggert Subject: Re: restrict Date: Mon, 17 Feb 2020 04:53:14 +0100 Message-ID: <2029541.RzEzKTdQOE@omega> User-Agent: KMail/5.1.3 (Linux/4.4.0-171-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: References: <20200209144434.GA19087@aun.utmark.mea> <11721813.x71fNvt2oN@omega> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a01:238:20a:202:5300::8 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: Tim =?ISO-8859-1?Q?R=FChsen?= , bug-gnulib@gnu.org, Mats Erik Andersson Errors-To: bug-gnulib-bounces+normalperson=yhbt.net@gnu.org Sender: "bug-gnulib" Paul Eggert wrote: > if GCC generated warnings for that sort of thing, the warnings would be false > alarms. Yes, and this in turn means that the ability to produce useful warnings via 'restrict' is limited. In this example: =================================================================== #include extern void memmcpy (void *restrict, const void *restrict, size_t); void shuffle (char array[10]) { memmcpy (array + 2, array, 8); memcpy (array + 2, array, 8); } =================================================================== gcc gives no warning about 'memmcpy' - because it does not know how many elements the function will access. gcc does give a warning about 'memcpy' - apparently due to custom logic in the compiler. Bruno