From patchwork Tue Oct 19 14:02:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Wakely X-Patchwork-Id: 1543320 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=gcc.gnu.org header.i=@gcc.gnu.org header.a=rsa-sha256 header.s=default header.b=gueAh/do; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=2620:52:3:1:0:246e:9693:128c; helo=sourceware.org; envelope-from=gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org; receiver=) Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4HYbBz4fQ0z9sP7 for ; Wed, 20 Oct 2021 01:06:35 +1100 (AEDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 3FAC63858024 for ; Tue, 19 Oct 2021 14:06:33 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3FAC63858024 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1634652393; bh=FUdTb7r/BjsFQW9qPB25dscF1fitT12fsRHopWEQOkU=; h=Date:To:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=gueAh/dorDqPQVKH7l83kiZD9DLZ1SSw8kGkYqilcRq88sHUYTlNjEKbGASPLI++X MH1T/8K3NW22QMaFR4wa8BjVeHQb1bwOCcruzX7Y/LZtNlxhia0P8gdZHIMus8DmM6 AvMp7SwLxHwwEWCwco3E4bIpXSMHRUFb7K0gsX/0= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org 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 EC96E385801A for ; Tue, 19 Oct 2021 14:02:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org EC96E385801A 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-296-5Homr3a5NzmQj-9WIb6tOQ-1; Tue, 19 Oct 2021 10:02:14 -0400 X-MC-Unique: 5Homr3a5NzmQj-9WIb6tOQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BBE16801B26; Tue, 19 Oct 2021 14:02:13 +0000 (UTC) Received: from localhost (unknown [10.33.36.194]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6DFB869219; Tue, 19 Oct 2021 14:02:13 +0000 (UTC) Date: Tue, 19 Oct 2021 15:02:12 +0100 To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [committed] libstdc++: Change std::variant union member to empty struct Message-ID: MIME-Version: 1.0 X-Clacks-Overhead: GNU Terry Pratchett X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP 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-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-Patchwork-Original-From: Jonathan Wakely via Gcc-patches From: Jonathan Wakely Reply-To: Jonathan Wakely Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Sender: "Gcc-patches" This more clearly expresses the intent (a completely unused, trivial type) than using char. It's also consistent with the unions in std::optional. libstdc++-v3/ChangeLog: * include/std/variant (_Uninitialized): Use an empty struct for the unused union member, instead of char. Tested powerpc64le-linux. Committed to trunk. commit 5a8832b1659e311437d25b7ec8b078be27ae54b8 Author: Jonathan Wakely Date: Tue Oct 19 11:53:27 2021 libstdc++: Change std::variant union member to empty struct This more clearly expresses the intent (a completely unused, trivial type) than using char. It's also consistent with the unions in std::optional. libstdc++-v3/ChangeLog: * include/std/variant (_Uninitialized): Use an empty struct for the unused union member, instead of char. diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant index d18365fde22..3da7dad1e82 100644 --- a/libstdc++-v3/include/std/variant +++ b/libstdc++-v3/include/std/variant @@ -293,8 +293,10 @@ namespace __variant constexpr _Type&& _M_get() && noexcept { return std::move(_M_storage); } + struct _Empty_byte { }; + union { - char _M_nope; + _Empty_byte _M_empty; _Type _M_storage; }; #else