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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id C69F4C4332F for ; Fri, 10 Nov 2023 11:44:12 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r1Pv1-0000bf-Ka; Fri, 10 Nov 2023 06:43:23 -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 1r1Pv0-0000Zi-0K for qemu-devel@nongnu.org; Fri, 10 Nov 2023 06:43:22 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r1Puy-0001DK-85 for qemu-devel@nongnu.org; Fri, 10 Nov 2023 06:43:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699616599; h=from:from:reply-to:reply-to:subject:subject: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=kRDjhwXQPNA+kVSRNZpHD99Z3R7j3cn2QnEVdGD2Zz4=; b=RUTch5ughZTHNFpKKVbEGbz1+K8IqwJDaqa5fX/buSVLmpuiWBhksZJmGNu72dtMIZGXk8 HWPt33l5sZhmltr9STql0Knu9Hne5ZYQA/LV1Ot1Mizik37OP2ev2H6BOt/qKQa6rtmK7P 59XJ47/o5b9JxCZsfwam29nzt9r2HiQ= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-272-exXiCJa1M82OprgTR86-OQ-1; Fri, 10 Nov 2023 06:43:17 -0500 X-MC-Unique: exXiCJa1M82OprgTR86-OQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 326AE3C1CC24; Fri, 10 Nov 2023 11:43:17 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.89]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E7935492BE7; Fri, 10 Nov 2023 11:43:15 +0000 (UTC) Date: Fri, 10 Nov 2023 11:43:14 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: BALATON Zoltan Cc: Manos Pitsidianakis , Peter Maydell , qemu-devel@nongnu.org, Paolo Bonzini , Gerd Hoffmann , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , qemu-arm@nongnu.org Subject: Re: [PATCH 2/2] Add warn_unused_result attr to AUD_register_card Message-ID: References: <4b040fc18cb0e563e92ce084ca18b89a050a8aaa.1699606819.git.manos.pitsidianakis@linaro.org> <3wmne.fhuf28sb5yfg@linaro.org> <02562baf-3d92-f5b4-2592-a9d868586451@eik.bme.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <02562baf-3d92-f5b4-2592-a9d868586451@eik.bme.hu> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Nov 10, 2023 at 12:35:56PM +0100, BALATON Zoltan wrote: > On Fri, 10 Nov 2023, Daniel P. Berrangé wrote: > > On Fri, Nov 10, 2023 at 12:44:56PM +0200, Manos Pitsidianakis wrote: > > > On Fri, 10 Nov 2023 12:21, Peter Maydell wrote: > > > > This kind of thing is why Coverity's unused-result warning has a > > > > lot of false positives. We shouldn't introduce extra code like > > > > this to work around the fact that the tooling doesn't understand > > > > our error-handling convention (i.e. error_fatal, and the way > > > > that some functions report errors both via the return value and > > > > also via the Error** argument). > > > > > > I respect that :). But I personally believe that clinging to C's > > > inadequacies, instead of preventing bugs statically just because it adds > > > some lines of code, is misguided. Proper code should strive to make bugs > > > impossible in the first place. At least that is my perspective and I would > > > like there to be constructive discussions about different approaches in the > > > mailing list. Perhaps something good might come out of it! > > > > Your approach to the problem: > > > > if (!AUD_register_card("OMAP EAC", &s->codec.card, &error_fatal)) { > > exit(1); > > } > > > > is adding dead-code because the exit(1) will never be reachable. So while > > it lets you squelch the unused result warning, it is verbose and misleading > > to anyone who sees it. > > > > Perhaps a more viable option is to pull in gnulib's ignore_value macro > > > > #define ignore_value(x) \ > > (__extension__ ({ __typeof__ (x) __x = (x); (void) __x; })) > > > > and then we would have just this: > > > > ignore_value(AUD_register_card("OMAP EAC", &s->codec.card, &error_fatal)); > > I wonder if just casting to (void) without assigning to a value could avoid > the warning? In that case you would not need a macro just > > (void)AUD_register_card("OMAP EAC", &s->codec.card, &error_fatal); Casting to void is not sufficient, which is why I suggested the ignore_value macro, which does enough to fool the compiler into thinking the return value is used. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|