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Sun, 13 Oct 2024 19:53:19 -0400 X-MC-Unique: XpdbpR9hNxSddpVxKVPLMQ-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D910F19560A3; Sun, 13 Oct 2024 23:53:18 +0000 (UTC) Received: from localhost (unknown [10.42.28.16]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4EBAA19560AA; Sun, 13 Oct 2024 23:53:17 +0000 (UTC) From: Jonathan Wakely To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [PATCH] libstdc++: Implement LWG 3798 for range adaptors [PR106676] Date: Mon, 14 Oct 2024 00:53:13 +0100 Message-ID: <20241013235316.1722410-1-jwakely@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.0 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_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham 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~incoming=patchwork.ozlabs.org@gcc.gnu.org Tested x86_64-linux. -- >8 -- LWG 3798 modified the iterator_category of the iterator types for transform_view, join_with_view, zip_transform_view and adjacent_transform_view, to allow the iterator's reference type to be an rvalue reference. libstdc++-v3/ChangeLog: PR libstdc++/106676 * include/bits/iterator_concepts.h (__cpp17_fwd_iterator): Use is_reference instead of is_value_reference. rvalue references. * include/std/ranges (transform_view:__iter_cat::_S_iter_cat): Likewise. (zip_transform_view::__iter_cat::_S_iter_cat): Likewise. (adjacent_transform_view::__iter_cat::_S_iter_cat): Likewise. (join_with_view::__iter_cat::_S_iter_cat): Likewise. * testsuite/std/ranges/adaptors/transform.cc: Check iterator_category when the transformation function returns an rvalue reference type. --- libstdc++-v3/include/bits/iterator_concepts.h | 4 +++- libstdc++-v3/include/std/ranges | 16 ++++++++++++---- .../testsuite/std/ranges/adaptors/transform.cc | 16 ++++++++++++++++ 3 files changed, 31 insertions(+), 5 deletions(-) diff --git a/libstdc++-v3/include/bits/iterator_concepts.h b/libstdc++-v3/include/bits/iterator_concepts.h index 490a362cdf1..669d3ddfd1e 100644 --- a/libstdc++-v3/include/bits/iterator_concepts.h +++ b/libstdc++-v3/include/bits/iterator_concepts.h @@ -333,10 +333,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION typename incrementable_traits<_Iter>::difference_type>; }; + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3798. Rvalue reference and iterator_category template concept __cpp17_fwd_iterator = __cpp17_input_iterator<_Iter> && constructible_from<_Iter> - && is_lvalue_reference_v> + && is_reference_v> && same_as>, typename indirectly_readable_traits<_Iter>::value_type> && requires(_Iter __it) diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index f0d81cbea0c..941189d65c3 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -1892,7 +1892,9 @@ namespace views::__adaptor using _Fpc = __detail::__maybe_const_t<_Const, _Fp>; using _Base = transform_view::_Base<_Const>; using _Res = invoke_result_t<_Fpc&, range_reference_t<_Base>>; - if constexpr (is_lvalue_reference_v<_Res>) + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3798. Rvalue reference and iterator_category + if constexpr (is_reference_v<_Res>) { using _Cat = typename iterator_traits>::iterator_category; @@ -5047,7 +5049,9 @@ namespace views::__adaptor using __detail::__range_iter_cat; using _Res = invoke_result_t<__maybe_const_t<_Const, _Fp>&, range_reference_t<__maybe_const_t<_Const, _Vs>>...>; - if constexpr (!is_lvalue_reference_v<_Res>) + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3798. Rvalue reference and iterator_category + if constexpr (!is_reference_v<_Res>) return input_iterator_tag{}; else if constexpr ((derived_from<__range_iter_cat<_Vs, _Const>, random_access_iterator_tag> && ...)) @@ -5820,7 +5824,9 @@ namespace views::__adaptor using _Res = invoke_result_t<__unarize<__maybe_const_t<_Const, _Fp>&, _Nm>, range_reference_t<_Base>>; using _Cat = typename iterator_traits>::iterator_category; - if constexpr (!is_lvalue_reference_v<_Res>) + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3798. Rvalue reference and iterator_category + if constexpr (!is_reference_v<_Res>) return input_iterator_tag{}; else if constexpr (derived_from<_Cat, random_access_iterator_tag>) return random_access_iterator_tag{}; @@ -7228,7 +7234,9 @@ namespace views::__adaptor using _OuterCat = typename iterator_traits<_OuterIter>::iterator_category; using _InnerCat = typename iterator_traits<_InnerIter>::iterator_category; using _PatternCat = typename iterator_traits<_PatternIter>::iterator_category; - if constexpr (!is_lvalue_reference_v, + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3798. Rvalue reference and iterator_category + if constexpr (!is_reference_v, iter_reference_t<_PatternIter>>>) return input_iterator_tag{}; else if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/transform.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/transform.cc index ca695349650..e1b74353e63 100644 --- a/libstdc++-v3/testsuite/std/ranges/adaptors/transform.cc +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/transform.cc @@ -214,6 +214,21 @@ test10() static_assert(std::same_as); } +void +test11() +{ + struct MoveIt { + int&& operator()(int& i) const { return std::move(i); } + }; + + int x[] {2, 4}; + auto xform = x | views::transform(MoveIt{}); + using iterator = decltype(xform.begin()); + // LWG 3798. Rvalue reference and iterator_category + using cat = std::iterator_traits::iterator_category; + static_assert(std::same_as); +} + int main() { @@ -227,4 +242,5 @@ main() test08(); test09(); test10(); + test11(); }