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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-8596] libstdc++: Fix minor bugs in std::common_iterator Date: Thu, 21 Jul 2022 11:16:59 +0000 (GMT) [thread overview] Message-ID: <20220721111659.80FFB385609C@sourceware.org> (raw) https://gcc.gnu.org/g:6a7ed225223bc8a13c5bbf4e77fbd7738b5b66d0 commit r12-8596-g6a7ed225223bc8a13c5bbf4e77fbd7738b5b66d0 Author: Jonathan Wakely <jwakely@redhat.com> Date: Wed Jul 20 12:49:28 2022 +0100 libstdc++: Fix minor bugs in std::common_iterator The noexcept-specifier for some std::common_iterator constructors was incorrectly using an rvalue as the first argument of std::is_nothrow_assignable_v. This gave the wrong answer for some types, e.g. std::common_iterator<int*, S>, because an rvalue of scalar type cannot be assigned to. Also fix the friend declaration to use the same constraints as on the definition of the class template. G++ fails to diagnose this error, due to PR c++/96830. Finally, the copy constructor was using std::move for its argument in some cases, which should be removed. libstdc++-v3/ChangeLog: * include/bits/stl_iterator.h (common_iterator): Fix incorrect uses of is_nothrow_assignable_v. Fix inconsistent constraints on friend declaration. Do not move argument in copy constructor. * testsuite/24_iterators/common_iterator/1.cc: Check for noexcept constructibnle/assignable. (cherry picked from commit 3b5567c3ec7e5759bdecc6a6fc0be2b65a93636e) Diff: --- libstdc++-v3/include/bits/stl_iterator.h | 11 ++++++----- .../testsuite/24_iterators/common_iterator/1.cc | 23 +++++++++++++++++++++- 2 files changed, 28 insertions(+), 6 deletions(-) diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index 12a89ab229f..35266722f66 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -1838,7 +1838,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _S_noexcept1() { if constexpr (is_trivially_default_constructible_v<_Tp>) - return is_nothrow_assignable_v<_Tp, _Up>; + return is_nothrow_assignable_v<_Tp&, _Up>; else return is_nothrow_constructible_v<_Tp, _Up>; } @@ -1932,14 +1932,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION if (_M_index == 0) { if constexpr (is_trivially_default_constructible_v<_It>) - _M_it = std::move(__x._M_it); + _M_it = __x._M_it; else std::construct_at(std::__addressof(_M_it), __x._M_it); } else if (_M_index == 1) { if constexpr (is_trivially_default_constructible_v<_Sent>) - _M_sent = std::move(__x._M_sent); + _M_sent = __x._M_sent; else std::construct_at(std::__addressof(_M_sent), __x._M_sent); } @@ -1964,8 +1964,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION operator=(const common_iterator<_It2, _Sent2>& __x) noexcept(is_nothrow_constructible_v<_It, const _It2&> && is_nothrow_constructible_v<_Sent, const _Sent2&> - && is_nothrow_assignable_v<_It, const _It2&> - && is_nothrow_assignable_v<_Sent, const _Sent2&>) + && is_nothrow_assignable_v<_It&, const _It2&> + && is_nothrow_assignable_v<_Sent&, const _Sent2&>) { switch(_M_index << 2 | __x._M_index) { @@ -2164,6 +2164,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION private: template<input_or_output_iterator _It2, sentinel_for<_It2> _Sent2> + requires (!same_as<_It2, _Sent2>) && copyable<_It2> friend class common_iterator; constexpr bool _M_has_value() const noexcept { return _M_index < 2; } diff --git a/libstdc++-v3/testsuite/24_iterators/common_iterator/1.cc b/libstdc++-v3/testsuite/24_iterators/common_iterator/1.cc index 365ee89c02e..ec4a86c862a 100644 --- a/libstdc++-v3/testsuite/24_iterators/common_iterator/1.cc +++ b/libstdc++-v3/testsuite/24_iterators/common_iterator/1.cc @@ -27,15 +27,30 @@ test01() using I = std::common_iterator<int*, const int*>; static_assert( std::is_default_constructible_v<I> ); static_assert( std::is_copy_constructible_v<I> ); + static_assert( std::is_move_constructible_v<I> ); static_assert( std::is_copy_assignable_v<I> ); + static_assert( std::is_move_assignable_v<I> ); static_assert( std::is_constructible_v<I, int*> ); static_assert( std::is_constructible_v<I, const int*> ); - struct sentinel { operator int*() const { return nullptr; } }; + static_assert( std::is_nothrow_copy_constructible_v<I> ); // GCC extension + static_assert( std::is_nothrow_move_constructible_v<I> ); // GCC extension + static_assert( std::is_nothrow_copy_assignable_v<I> ); // GCC extension + static_assert( std::is_nothrow_move_assignable_v<I> ); // GCC extension + + struct sentinel { operator int*() const noexcept { return nullptr; } }; using K = std::common_iterator<int*, sentinel>; static_assert( std::is_constructible_v<I, const K&> ); static_assert( std::is_assignable_v<I, const K&> ); + static_assert( std::is_nothrow_assignable_v<I&, const K&> ); // GCC extension + + struct sentinel_throwing { operator int*() const { return nullptr; } }; + using K_throwing = std::common_iterator<int*, sentinel_throwing>; + // Conversion is noexcept(false) + static_assert( ! std::is_nothrow_assignable_v<I&, const K_throwing&> ); + + struct sentinel2 { const int* p; @@ -46,6 +61,12 @@ test01() using J = std::common_iterator<const int*, sentinel2>; static_assert( std::is_constructible_v<J, const I&> ); static_assert( std::is_convertible_v<const I&, J> ); + + static_assert( std::is_constructible_v<J, I> ); + static_assert( std::is_convertible_v<I, J> ); + + // Constructor is noexcept(false) + static_assert( ! std::is_nothrow_constructible_v<J, I> ); } void
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