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Thu, 11 Sep 2025 21:40:51 +0000 (UTC) Received: from zen.kayari.org (unknown [10.42.28.196]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 52DDF18004D8; Thu, 11 Sep 2025 21:40:50 +0000 (UTC) From: Jonathan Wakely To: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org Subject: [PATCH] libstdc++: ranges::rotate should use ranges::iter_move [PR121913] Date: Thu, 11 Sep 2025 22:39:47 +0100 Message-ID: <20250911214048.1648969-1-jwakely@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: p9Y6PRy0IOfJYoojXheALWWS-uMntpETjcrxE3Rie4o_1757626851 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.3 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_NONE, RCVD_IN_MSPIKE_H5, RCVD_IN_MSPIKE_WL, RCVD_IN_VALIDITY_RPBL_BLOCKED, RCVD_IN_VALIDITY_SAFE_BLOCKED, SPF_HELO_PASS, SPF_NONE, TXREP, URI_HEX autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces~patchwork=sourceware.org@gcc.gnu.org Using std::move(*it) is incorrect for iterators that use proxy refs, we should use ranges::iter_move(it) instead. libstdc++-v3/ChangeLog: PR libstdc++/121913 * include/bits/ranges_algo.h (__rotate_fn::operator()): Use ranges::iter_move(it) instead of std::move(*it). * testsuite/25_algorithms/rotate/121913.cc: New test. --- The testcase is highly contrived, but the fix seems worth doing anyway. Tested powerpc64le-linux. libstdc++-v3/include/bits/ranges_algo.h | 4 +- .../testsuite/25_algorithms/rotate/121913.cc | 45 +++++++++++++++++++ 2 files changed, 47 insertions(+), 2 deletions(-) create mode 100644 libstdc++-v3/testsuite/25_algorithms/rotate/121913.cc diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h index 609b82e26d8a..9b348d82ce55 100644 --- a/libstdc++-v3/include/bits/ranges_algo.h +++ b/libstdc++-v3/include/bits/ranges_algo.h @@ -1685,7 +1685,7 @@ namespace ranges { auto __mid = ranges::next(__p, __n - 1); auto __end = ranges::next(__mid); - auto __t = std::move(*__p); + auto __t = ranges::iter_move(__p); ranges::move(ranges::next(__p), __end, __p); *__mid = std::move(__t); return {std::move(__ret), std::move(__lasti)}; @@ -1713,7 +1713,7 @@ namespace ranges { auto __mid = ranges::next(__p, __n - 1); auto __end = ranges::next(__mid); - auto __t = std::move(*__mid); + auto __t = ranges::iter_move(__mid); ranges::move_backward(__p, __mid, __end); *__p = std::move(__t); return {std::move(__ret), std::move(__lasti)}; diff --git a/libstdc++-v3/testsuite/25_algorithms/rotate/121913.cc b/libstdc++-v3/testsuite/25_algorithms/rotate/121913.cc new file mode 100644 index 000000000000..d648699adbda --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/rotate/121913.cc @@ -0,0 +1,45 @@ +// { dg-do compile { target c++20 } } + +// Bug libstdc++/121913 ranges::rotate should use ranges::iter_move + +#include + +struct A { }; + +struct B +{ + B& operator=(const B&) = delete; + B& operator=(const A&) const; + + operator A() const; +}; + +struct I +{ + using value_type = A; + using difference_type = int; + B operator*() const; + B operator[](int) const; + I& operator++(); + I operator++(int); + I& operator--(); + I operator--(int); + I& operator+=(int); + I& operator-=(int); + + auto operator<=>(const I&) const = default; + + friend A iter_move(const I&); + friend I operator+(I, int); + friend I operator-(I, int); + friend I operator+(int, I); + friend int operator-(I, I); +}; + +static_assert( std::random_access_iterator ); + +void +test_pr121913() +{ + std::ranges::rotate(I{}, I{}, I{}); +}