From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 9AF00385E447 for ; Wed, 19 May 2021 16:56:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 9AF00385E447 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-213-rxQ1K3mOOsiFciYj8XoEHA-1; Wed, 19 May 2021 12:56:12 -0400 X-MC-Unique: rxQ1K3mOOsiFciYj8XoEHA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B1F80107ACCD; Wed, 19 May 2021 16:56:11 +0000 (UTC) Received: from localhost (unknown [10.33.36.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 515605C1CF; Wed, 19 May 2021 16:56:11 +0000 (UTC) Date: Wed, 19 May 2021 17:56:10 +0100 From: Jonathan Wakely To: Eric Gallager Cc: gcc-patches Subject: Re: [PATCH] c++: Add new warning options for C++ language mismatches Message-ID: References: MIME-Version: 1.0 In-Reply-To: X-Clacks-Overhead: GNU Terry Pratchett X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline X-Spam-Status: No, score=-8.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 May 2021 16:56:17 -0000 On 19/05/21 17:50 +0100, Jonathan Wakely wrote: >On 19/05/21 12:40 -0400, Eric Gallager wrote: >>Thank you for doing this! One thing I'm wondering about, is that I'm >>pretty sure clang also allows at least some of these to be used with >>plain C as well, for example for things like the old use of "auto" in >>C conflicting with the newer C++11 meaning of "auto". Would it be >>possible to do likewise for GCC as well? Just an idea. > >I think that would belong in -Wc++-compat and would need changes to >the C front end, which I'm almost entirely unfamiliar with. My patch >doesn't add any new diagnostics, it just makes slight adjustments to >existing ones. If you want new diagnostics in the C front end you'll >need to convince a C FE maintainer. That would be too far outside my >comfort zone :-) FWIW, Clang does accept -Wc++11-extensions as an option for the C compiler, but I think that's true for all its warning options (I don't think it ever rejects a warning option as "valid for C++ but not for C" the way that GCC does). But I can't persuade it to warn about using 'auto' in C, even with -Weverything.