From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20483 invoked by alias); 5 Sep 2016 16:46:34 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 20471 invoked by uid 89); 5 Sep 2016 16:46:33 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS,URIBL_RED autolearn=ham version=3.3.2 spammy=Hx-languages-length:505 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 05 Sep 2016 16:46:32 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=svr-ies-mbx-01.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1bgx2U-0007d6-3C from joseph_myers@mentor.com ; Mon, 05 Sep 2016 09:46:30 -0700 Received: from digraph.polyomino.org.uk (137.202.0.87) by svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) with Microsoft SMTP Server (TLS) id 15.0.1210.3; Mon, 5 Sep 2016 17:46:26 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.86_2) (envelope-from ) id 1bgx2M-0007KX-OY; Mon, 05 Sep 2016 16:46:22 +0000 Date: Mon, 05 Sep 2016 16:57:00 -0000 From: Joseph Myers To: Bernd Edlinger CC: "gcc-patches@gcc.gnu.org" , Jason Merrill Subject: Re: [PATCHv2] Add a warning for suspicious use of conditional expressions in boolean context In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) X-SW-Source: 2016-09/txt/msg00222.txt.bz2 On Mon, 5 Sep 2016, Bernd Edlinger wrote: > But I think the reasoning is still correct, left shifting > in a boolean context is suspicious, even if -fwrapv may make > it defined. Do you agree? Well, you can argue that if you want to test whether low bits are all zero, you should just use binary & with a suitable mask, or else cast to unsigned for the left shift. -- Joseph S. Myers joseph@codesourcery.com