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 EE0A83858D39 for ; Tue, 19 Sep 2023 20:24:30 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org EE0A83858D39 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695155070; h=from:from: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=8HxjYQK102sx2+e0nKrvOMfuIzUOtGvziFdMrVN2q2c=; b=EImnByz55lST0+Z3FkWDivq/dWX2eqtS5XK2KyvBYywP5XtBtYiIQhfpdbbSn55fSDLDKb fd+bplOhjJPCFV4tm+EFUfuFWxRagavsjS3sjRFGcOoJn7DLUfxvrwCX5QnuYc5ZHRVQRe adeap9MoptY3jq+nn9IP0ByMZK+F7bE= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-88-mbQOmYVBOAupTcu40lBb8A-1; Tue, 19 Sep 2023 16:24:29 -0400 X-MC-Unique: mbQOmYVBOAupTcu40lBb8A-1 Received: by mail-qv1-f70.google.com with SMTP id 6a1803df08f44-6562fff4a2fso54821456d6.3 for ; Tue, 19 Sep 2023 13:24:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695155069; x=1695759869; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8HxjYQK102sx2+e0nKrvOMfuIzUOtGvziFdMrVN2q2c=; b=q6dnZp3YQKhQoyMZGsB5JsqnQ6HqT/0+gYkY8tt1Lk0MRWvTIk4Fv/4qhlkvfHA+AM hjaJb9uaYy2/QsLbcex7cG6u0XgPQVLJn25JRpQbLyDIfz9RWCXadq+0XKhZb1WvIsby 4qobTca8xBa0t32xQL+DLC3dagNbC5IyEuzQqVBViywC1csnswlqemXRjiOOizIx76f1 ppUhQnKkiT0NcSyk2LzVqu8rVOCdyVD2KhHSbaF4DsNApOGiHSGDVwUSJtX9GmLsy/Nv QJkzaxWkWo4mfPxvE5BuWaUDQ4YKmsEmdehpkzng8df2MA4lol1gfuowifd+DnRSuugy 5weQ== X-Gm-Message-State: AOJu0YzJxTcNcj0NB/zi3LrVFH4PwMMs04wbPSSGqWGJdyIKyR5YeWNx +4wN4OJe6tdTVI6Fye6yxoLcVPXepATgS5jcCvk25ZueItg7kdPXT6ZhljpRORiGiZj5rurVRuE kT/fFCrwjoF3eWadaZQ== X-Received: by 2002:a0c:a98f:0:b0:64f:4240:8e1b with SMTP id a15-20020a0ca98f000000b0064f42408e1bmr434614qvb.44.1695155068773; Tue, 19 Sep 2023 13:24:28 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFydk79jXWsJ1Id5kjBgce0wXB/eqsiGYTXxfR6fA1DZVn3IE/bJ8QKhW/rDkUs2Mj5MgArxA== X-Received: by 2002:a0c:a98f:0:b0:64f:4240:8e1b with SMTP id a15-20020a0ca98f000000b0064f42408e1bmr434603qvb.44.1695155068528; Tue, 19 Sep 2023 13:24:28 -0700 (PDT) Received: from [192.168.1.108] (130-44-146-16.s12558.c3-0.arl-cbr1.sbo-arl.ma.cable.rcncustomer.com. [130.44.146.16]) by smtp.gmail.com with ESMTPSA id a25-20020a0c8bd9000000b0065359e0a3efsm2851636qvc.36.2023.09.19.13.24.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Sep 2023 13:24:28 -0700 (PDT) Message-ID: Date: Tue, 19 Sep 2023 16:24:26 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH 1/2] c++: Initial support for P0847R7 (Deducing This) [PR102609] To: Jakub Jelinek , waffl3x Cc: "gcc-patches@gcc.gnu.org" References: From: Jason Merrill In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-7.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 8/31/23 04:33, Jakub Jelinek wrote: > On Thu, Aug 31, 2023 at 06:02:36AM +0000, waffl3x via Gcc-patches wrote: > >> +++ b/gcc/testsuite/g++.dg/cpp23/explicit-object-param-valid2.C >> @@ -0,0 +1,24 @@ >> +// P0847R7 >> +// { dg-do run { target c++23 } } > > This raises an important question whether we as an extension > should support deducing this even in older standards or not. > I admit I haven't studied the paper enough to figure that out. > The syntax is certainly something that wasn't valid in older standards, > so from that POV it could be accepted say with pedwarn with > OPT_Wc__23_extensions if cxx_dialect < cxx23. But perhaps some > of the rules in the paper change something unconditionally even when > the new syntax doesn't appear. > And, if it is accepted in older standards, the question is if it > shouldn't be banned say from C++98. I don't think there's any obstacle to allowing it as an extension in older standards (with a pedwarn, of course). Jason