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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 7F809C433E0 for ; Tue, 12 Jan 2021 11:42:17 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1F6BF23104 for ; Tue, 12 Jan 2021 11:42:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F6BF23104 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.65641.116325 (Exim 4.92) (envelope-from ) id 1kzI3m-0007qJ-FI; Tue, 12 Jan 2021 11:42:02 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 65641.116325; Tue, 12 Jan 2021 11:42:02 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kzI3m-0007qC-Ag; Tue, 12 Jan 2021 11:42:02 +0000 Received: by outflank-mailman (input) for mailman id 65641; Tue, 12 Jan 2021 11:42:00 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kzI3k-0007q7-3x for xen-devel@lists.xenproject.org; Tue, 12 Jan 2021 11:42:00 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id ba0bf594-928e-4140-a12c-47b521d0e383; Tue, 12 Jan 2021 11:41:59 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 78ED1AFA0; Tue, 12 Jan 2021 11:41:58 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: ba0bf594-928e-4140-a12c-47b521d0e383 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1610451718; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sJEwHCFfDkbCePONnitGPierf2RfjEn6421gh2g560c=; b=ESd5AdYcQgOqpBC3Vwg85HZyzkSmzzKCHwGWBiiLLbJbl65MiQexT+X58pgmTl/kQOiDoy O6VYRqH/Y0DTAFXY7O/vf1AzSpAOeNIoPoaesbJkJfz/TymtC3ZBu58BWo90NbfBvZCwx/ 1UDlELlPw4oh7jD6PkQ6q8tMZaVS3eA= Subject: Re: [PATCH v4 08/11] xen/compiler: import 'fallthrough' keyword from linux To: Rahul Singh Cc: bertrand.marquis@arm.com, Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: From: Jan Beulich Message-ID: <9dd27a7d-a77a-14ff-c62c-c813b21fb34e@suse.com> Date: Tue, 12 Jan 2021 12:41:57 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 08.01.2021 15:46, Rahul Singh wrote: > -Wimplicit-fallthrough warns when a switch case falls through. Warning > can be suppress by either adding a /* fallthrough */ comment, or by > using a null statement: __attribute__ ((fallthrough)) Why is the comment variant (which we use in many places already, albeit with varying wording) not the route of choice? > Define the pseudo keyword 'fallthrough' for the ability to convert the > various case block /* fallthrough */ style comments to null statement > "__attribute__((__fallthrough__))" > > In C mode, GCC supports the __fallthrough__ attribute since 7.1, > the same time the warning and the comment parsing were introduced. > > fallthrough devolves to an empty "do {} while (0)" if the compiler > version (any version less than gcc 7) does not support the attribute. What about Coverity? It would be nice if we wouldn't need to add two separate constructs everywhere to make both compiler and static code checker happy. Jan