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 B8BBB3858433 for ; Tue, 19 Oct 2021 14:02:18 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B8BBB3858433 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 From: Jonathan Wakely 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-Type: multipart/mixed; boundary="9vzcCngFWQsVsjmx" 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=unavailable autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org 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: Tue, 19 Oct 2021 14:02:20 -0000 --9vzcCngFWQsVsjmx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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. --9vzcCngFWQsVsjmx Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="patch.txt" 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 --9vzcCngFWQsVsjmx--