From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18740 invoked by alias); 12 Jun 2017 16:55:09 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 18725 invoked by uid 89); 12 Jun 2017 16:55:08 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy= X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 12 Jun 2017 16:55:07 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A2D5AC057FA5; Mon, 12 Jun 2017 16:55:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com A2D5AC057FA5 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=palves@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com A2D5AC057FA5 Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id A4FE862927; Mon, 12 Jun 2017 16:55:05 +0000 (UTC) Subject: Re: [PATCH 0/5] Remove a few hurdles of compiling with clang To: Andrew Pinski References: <1497124689-11842-1-git-send-email-simon.marchi@ericsson.com> <83tw3n5jyk.fsf@gnu.org> <86tw3labb0.fsf@gmail.com> <83a85d5l4n.fsf@gnu.org> <93eb64489ac9d53665a144ddf5a966d5@polymtl.ca> <72d32638-ce7b-d362-5efd-84e8d89431d4@redhat.com> <5669db7c-e3c1-3aa6-5f78-dca817b44ba1@redhat.com> Cc: Simon Marchi , Eli Zaretskii , Yao Qi , Simon Marchi , "gdb-patches@sourceware.org" From: Pedro Alves Message-ID: <4bc68337-43ad-cf49-da1f-f7f9b6ffdd09@redhat.com> Date: Mon, 12 Jun 2017 16:55:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <5669db7c-e3c1-3aa6-5f78-dca817b44ba1@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2017-06/txt/msg00336.txt.bz2 On 06/12/2017 05:45 PM, Pedro Alves wrote: > On 06/12/2017 05:37 PM, Andrew Pinski wrote: >> On Mon, Jun 12, 2017 at 9:35 AM, Pedro Alves wrote: >>> On 06/12/2017 05:23 PM, Andrew Pinski wrote: >>>> On Mon, Jun 12, 2017 at 8:54 AM, Simon Marchi wrote: >>> >>>>> - gdb: Add -Wno-mismatched-tags: We already have a system that tests which >>>>> warning flags are supported by the current compiler, so this flag will not >>>>> be included in the builds with GCC. So it's neutral for GCC, and improves >>>>> the situation for Clang with almost no effort. >>>> >>>> This warning is a bug in clang and really should not be warned about >>>> in either -Wall or -Wextra. I have been complaining about this since >>>> clang added this option. >>> >>> IIRC, the reason this warning exists is because Microsoft's compilers >>> mangle "struct" and "class" differently, so for projects that >>> want to be portable to that compiler, it's a helpful warning. >>> (Whether that should ever be part of -Wall is a separate matter...) >>> >>> I don't think we'd want to bend backwards to support MSVC >>> though. It's so non-conforming that it's scary. Disabling >>> that warning is the right thing to do, IMO. >> >> Why not have clang disable this warning by default instead? > > You'll have to ask clang developers. > >> I am sorry but people who write C++ should understand that they are the same. > > We know the standard says so, and I know that that's true on the ABIs > we care about. But in practice, what compilers (a project > cares about) matters more than what the standard says. After all, > if the standard says the language does X, but no gcc behaves that > way, we wouldn't ever want code to depend on X, would we? For reference, so no one thinks I'm making this up: :-) https://bugzilla.mozilla.org/show_bug.cgi?id=1026535 Thanks, Pedro Alves