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 [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 25A153858427 for ; Mon, 9 May 2022 09:26:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 25A153858427 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-52-9e1zOBcsOcm7EDnKo1zimQ-1; Mon, 09 May 2022 05:26:27 -0400 X-MC-Unique: 9e1zOBcsOcm7EDnKo1zimQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6597329AB3E2 for ; Mon, 9 May 2022 09:26:27 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.246]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8E4252166B49; Mon, 9 May 2022 09:26:25 +0000 (UTC) From: Florian Weimer To: Ulrich Drepper via Gcc Cc: Ulrich Drepper Subject: Re: -Wformat and u8"" References: Date: Mon, 09 May 2022 11:26:24 +0200 In-Reply-To: (Ulrich Drepper via Gcc's message of "Mon, 9 May 2022 11:15:44 +0200") Message-ID: <87wnevcb0f.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 May 2022 09:26:30 -0000 * Ulrich Drepper via Gcc: > t.cc: In function =E2=80=98int main()=E2=80=99: > t.cc:5:24: warning: format string is not an array of type =E2=80=98char= =E2=80=99 [-Wformat=3D] > 5 | printf((const char*) u8"test %d\n", 1); > | ^~~~~~~~~~~~~ This is not an aliasing violation because of the exception for char, right? So the warning does not even highlight theoretical undefined behavior. On the other hand, that cast is still quite ugly. All string-related functions in the C library currently need it. It might obscure real type errors. Isn't this a problem with char8_t? Thanks, Florian