From 6fedf28c7921f125be75a9f688a7b845a1b5663b Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Thu, 7 May 2020 17:39:56 +0100 Subject: [PATCH] libstdc++: Replace deduced return type in ranges::iter_move (PR 92894) The deduced return type causes the instantiation of the function body, which can then require the instantiation of std::projected::operator* which is intentionally not defined. This patch uses a helper trait to define the return type, so that the function body doesn't need to be instantiated. Unlike on the master branch, this backport to gcc-10 does not change the iter_rvalue_reference_t alias template and __indirectly_readable_impl concept to use the new trait. Backport from mainline 2020-05-01 Jonathan Wakely Patrick Palka PR libstdc++/92894 * include/bits/iterator_concepts.h (ranges::__cust_imove::_IMove): Add trait to determine return type and an alias for it. (ranges::__cust_imove::_IMove::operator()): Use __result instead of deduced return type. * testsuite/24_iterators/customization_points/92894.cc: New test. * testsuite/24_iterators/indirect_callable/92894.cc: New test. Co-authored-by: Patrick Palka --- libstdc++-v3/ChangeLog | 14 +++++ libstdc++-v3/include/bits/iterator_concepts.h | 28 ++++++++-- .../customization_points/92894.cc | 52 ++++++++++++++++++ .../24_iterators/indirect_callable/92894.cc | 55 +++++++++++++++++++ 4 files changed, 144 insertions(+), 5 deletions(-) create mode 100644 libstdc++-v3/testsuite/24_iterators/customization_points/92894.cc create mode 100644 libstdc++-v3/testsuite/24_iterators/indirect_callable/92894.cc diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 70e296622e7e..55d975b84fc1 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,17 @@ +2020-05-07 Jonathan Wakely + + Backport from mainline + 2020-05-01 Jonathan Wakely + Patrick Palka + + PR libstdc++/92894 + * include/bits/iterator_concepts.h (ranges::__cust_imove::_IMove): + Add trait to determine return type and an alias for it. + (ranges::__cust_imove::_IMove::operator()): Use __result instead of + deduced return type. + * testsuite/24_iterators/customization_points/92894.cc: New test. + * testsuite/24_iterators/indirect_callable/92894.cc: New test. + 2020-05-07 Release Manager * GCC 10.1.0 released. diff --git a/libstdc++-v3/include/bits/iterator_concepts.h b/libstdc++-v3/include/bits/iterator_concepts.h index b598532089e9..c5b6247cde7d 100644 --- a/libstdc++-v3/include/bits/iterator_concepts.h +++ b/libstdc++-v3/include/bits/iterator_concepts.h @@ -89,6 +89,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION struct _IMove { private: + template + struct __result + { using type = iter_reference_t<_Tp>; }; + + template + requires __adl_imove<_Tp> + struct __result<_Tp> + { using type = decltype(iter_move(std::declval<_Tp>())); }; + + template + requires (!__adl_imove<_Tp>) + && is_lvalue_reference_v> + struct __result<_Tp> + { using type = remove_reference_t>&&; }; + template static constexpr bool _S_noexcept() @@ -100,16 +115,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } public: - template - requires __adl_imove<_Tp> || requires(_Tp& __e) { *__e; } - constexpr decltype(auto) + // The result type of iter_move(std::declval<_Tp>()) + template + using __type = typename __result<_Tp>::type; + + template + constexpr __type<_Tp> operator()(_Tp&& __e) const noexcept(_S_noexcept<_Tp>()) { if constexpr (__adl_imove<_Tp>) return iter_move(static_cast<_Tp&&>(__e)); - else if constexpr (is_reference_v>) - return std::move(*__e); + else if constexpr (is_lvalue_reference_v>) + return static_cast<__type<_Tp>>(*__e); else return *__e; } diff --git a/libstdc++-v3/testsuite/24_iterators/customization_points/92894.cc b/libstdc++-v3/testsuite/24_iterators/customization_points/92894.cc new file mode 100644 index 000000000000..197268fe5e33 --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/customization_points/92894.cc @@ -0,0 +1,52 @@ +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// . + +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +#include + +using namespace std; + +// Define our own of version of indirectly_readable_impl here, +// to check the use of iter_move even if the real concept in +// no longer uses iter_move. +template +concept indirectly_readable_impl + = requires(const In in) + { + typename iter_value_t; + typename iter_reference_t; + typename iter_rvalue_reference_t; + { *in } -> same_as>; + { ranges::iter_move(in) } -> same_as>; + }; + +template requires indirectly_readable_impl> + void algo(T) + { } + +void +test01() +{ + // PR libstdc++/92894 + // Verify that the use of range::iter_move above doesn't cause odr-use of + // projected::operator* (which is not defined). + struct X { }; + X a; + algo(a); +} diff --git a/libstdc++-v3/testsuite/24_iterators/indirect_callable/92894.cc b/libstdc++-v3/testsuite/24_iterators/indirect_callable/92894.cc new file mode 100644 index 000000000000..3408c76bde1f --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/indirect_callable/92894.cc @@ -0,0 +1,55 @@ +// Copyright (C) 2020 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// . + +// { dg-options "-std=gnu++2a" } +// { dg-do compile { target c++2a } } + +#include + +using std::projected; +using std::identity; +using std::indirect_unary_predicate; + +template> Pred> + constexpr void + all_of(T*, Pred) + { } + +void +test01() +{ + // PR libstdc++/92894 + struct X { }; + X x; + all_of(&x, [](X&) { return false; }); +} + +template> Pred> + constexpr void + find_if(R, Pred, Proj = {}) + { } + +void +test02() +{ + // PR 94241 + struct s { int m; }; + s r[] = { s{0}, s{1}, s{2}, s{3} }; + find_if(r, [](auto const) { return true; }); +} -- 2.47.2