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 ESMTP id 5E326388A81E for ; Tue, 17 Aug 2021 13:26:59 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5E326388A81E 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-418-yyO6kdYEMhKHehYxENoyNA-1; Tue, 17 Aug 2021 09:26:57 -0400 X-MC-Unique: yyO6kdYEMhKHehYxENoyNA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A3AC6801AEB; Tue, 17 Aug 2021 13:26:56 +0000 (UTC) Received: from localhost (unknown [10.33.36.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4DFAA10013D7; Tue, 17 Aug 2021 13:26:56 +0000 (UTC) Date: Tue, 17 Aug 2021 14:26:55 +0100 From: Jonathan Wakely To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [committed] libstdc++: Add conditional noexcept to std::exchange Message-ID: MIME-Version: 1.0 X-Clacks-Overhead: GNU Terry Pratchett X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/mixed; boundary="qsNI2IBJtdRA7aJY" Content-Disposition: inline X-Spam-Status: No, score=-14.2 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: 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, 17 Aug 2021 13:27:09 -0000 --qsNI2IBJtdRA7aJY Content-Type: text/plain; charset=us-ascii Content-Disposition: inline This is not required by the standard, but seems useful. Signed-off-by: Jonathan Wakely libstdc++-v3/ChangeLog: * include/std/utility (exchange): Add noexcept-specifier. * testsuite/20_util/exchange/noexcept.cc: New test. Tested powerpc64le-linux. Committed to trunk. --qsNI2IBJtdRA7aJY Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="patch.txt" commit 42cfa1bd6c05f2dc0d6269155950d16064310f56 Author: Jonathan Wakely Date: Mon Aug 16 18:00:08 2021 libstdc++: Add conditional noexcept to std::exchange This is not required by the standard, but seems useful. Signed-off-by: Jonathan Wakely libstdc++-v3/ChangeLog: * include/std/utility (exchange): Add noexcept-specifier. * testsuite/20_util/exchange/noexcept.cc: New test. diff --git a/libstdc++-v3/include/std/utility b/libstdc++-v3/include/std/utility index c2697f87dc5..69d274ff194 100644 --- a/libstdc++-v3/include/std/utility +++ b/libstdc++-v3/include/std/utility @@ -91,6 +91,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _GLIBCXX20_CONSTEXPR inline _Tp exchange(_Tp& __obj, _Up&& __new_val) + noexcept(__and_, + is_nothrow_assignable<_Tp&, _Up>>::value) { return std::__exchange(__obj, std::forward<_Up>(__new_val)); } #if __cplusplus >= 201703L diff --git a/libstdc++-v3/testsuite/20_util/exchange/noexcept.cc b/libstdc++-v3/testsuite/20_util/exchange/noexcept.cc new file mode 100644 index 00000000000..6363a4d4c06 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/exchange/noexcept.cc @@ -0,0 +1,39 @@ +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +#include + +// This is a GCC extension. std::exchange is not required to be noexcept. + +static_assert( noexcept( std::exchange(std::declval(), 1) ) ); + +struct X +{ + X(const X&); + X(X&&) noexcept; + X& operator=(const X&); + X& operator=(X&&) noexcept; + X& operator=(int); +}; + +extern X x, x2; +static_assert( noexcept( std::exchange(x, std::move(x2)) ) ); +static_assert( ! noexcept( std::exchange(x, 1) ) ); + +struct Y +{ + Y(Y&&) noexcept; + Y& operator=(Y&&); +}; + +extern Y y, y2; +static_assert( ! noexcept( std::exchange(y, std::move(y2)) ) ); + +struct Z +{ + Z(Z&&)noexcept; + Z& operator=(Z&&) ; +}; + +extern Z z, z2; +static_assert( ! noexcept( std::exchange(z, std::move(z2)) ) ); --qsNI2IBJtdRA7aJY--