From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by sourceware.org (Postfix) with ESMTPS id 686F0385841B; Fri, 11 Feb 2022 19:47:57 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 686F0385841B Received: by mail-wr1-x431.google.com with SMTP id u1so3197727wrg.11; Fri, 11 Feb 2022 11:47:57 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=x9O3hshjaPKdcU9RgVAZCa+Mr3VwUDUo1SJacy7bqu8=; b=sTThKOmoAD6bQSASRv6e/5R3QtHpx4E+4uhRJAQGJsf0BQDewxjkXZAPXq/6m6TeiY YEuedHolI4a+UVffyi56lSn9P4HML8qYI65sWOZPWvZCf+h3R7O9fyqEJmNbATbMokAA psyYMRnGebR9qKrNmJkD0nHzY1n6NWJfbfIY4pvvwFPFx4gB0CoZyoGmFuJoTp+wDH5o tKkGjeX/My/YFtSa8yrr9hcaI72W1RMK/5b2hfkkIeg31c98OOiTDaUJ7fMNpVLrYnjl CI07APgYCGr3DzK/c3tdb8AXSSqfmCzbvKmsF7d2nCONVo2uPWiJdyiRlQhM5Kg/nRxw n9BQ== X-Gm-Message-State: AOAM532Rs+3WOniJ5UdUh4OgvAAJe6cuts+3RAwq7Q6I2cBMxd/s4LMG y5fbE28R8xnNStyw5H2Zz6eHWFNZ8RLSEOJc+Mk= X-Google-Smtp-Source: ABdhPJzFASXdZ9fvG7/5iN0jP7154cE2388CnNZptD6CCc8x+o4/sQugx5gpos0HjOROVAgZ7FpfD8TDUmLJfodvOrs= X-Received: by 2002:a5d:4c86:: with SMTP id z6mr2546484wrs.568.1644608876299; Fri, 11 Feb 2022 11:47:56 -0800 (PST) MIME-Version: 1.0 References: <20220211165157.3159659-1-ppalka@redhat.com> In-Reply-To: From: Jonathan Wakely Date: Fri, 11 Feb 2022 19:47:45 +0000 Message-ID: Subject: Re: [PATCH] libstdc++: Back out some changes in P2325R3 backport [PR103904] To: Patrick Palka Cc: "libstdc++" , gcc-patches X-Spam-Status: No, score=-0.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, 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 Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: libstdc++@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++ mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Feb 2022 19:47:59 -0000 On Fri, 11 Feb 2022, 17:11 Patrick Palka via Libstdc++, < libstdc++@gcc.gnu.org> wrote: > On Fri, 11 Feb 2022, Patrick Palka wrote: > > > In the P2325R3 backport r11-9555 the relaxation of the constraints on > > the partial specialization of __box (which is semantically equivalent to > > the primary template, only more space efficient) means some > > specializations of __box will now use the partial specialization instead > > of the primary template, which (IIUC) constitutes an ABI change > unsuitable > > for a release branch. This patch reverts this constraint change, which > > isn't needed for correctness anyway. > > > > Similarly the change to use __non_propagating_cache for the data member > > split_view::_M_current (so that it's always default-initializable) also > > constitutes an unsuitable ABI change. This patch reverts this change > > too, and instead further constrains split_view's default constructor to > > require that we can default-initialize _M_current. > > Forgot to clarify that this is for the 11 branch, tested on > x86_64-pc-linux-gnu. Does this look reasonable? I noticed these > issues while backporting r11-9555 to the 10 branch, which doesn't have > __non_propagating_cache or the partial specialization of __box. > Yes, thanks for spotting the problem. OK for gcc-11.