[gcc(refs/users/aoliva/heads/testme)] libstdc++: Constrain reverse_iterator and move_iterator conversions [LWG 3435]
Alexandre Oliva
aoliva@gcc.gnu.org
Fri Jul 24 13:14:34 GMT 2020
https://gcc.gnu.org/g:a5a8a4e61565a2a66391e29eb80813c581b7dc52
commit a5a8a4e61565a2a66391e29eb80813c581b7dc52
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Wed Jul 22 13:25:11 2020 +0100
libstdc++: Constrain reverse_iterator and move_iterator conversions [LWG 3435]
libstdc++-v3/ChangeLog:
* include/bits/stl_iterator.h (reverse_iterator): Constrain
converting constructor and converting assignment operator.
Access source iterator's data member directly instead of
calling base().
(move_iterator): Likewise.
* testsuite/24_iterators/move_iterator/dr3435.cc: New test.
* testsuite/24_iterators/reverse_iterator/dr3435.cc: New test.
Diff:
---
libstdc++-v3/include/bits/stl_iterator.h | 55 ++++++++++++++++++++--
.../testsuite/24_iterators/move_iterator/dr3435.cc | 37 +++++++++++++++
.../24_iterators/reverse_iterator/dr3435.cc | 36 ++++++++++++++
3 files changed, 125 insertions(+), 3 deletions(-)
diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index 6d2d19eb068..60bb40a659f 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -129,6 +129,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typename iterator_traits<_Iterator>::pointer,
typename iterator_traits<_Iterator>::reference>
{
+#if __cplusplus >= 201103L
+ template<typename _Iter>
+ friend class reverse_iterator;
+#endif
+
+#if __cpp_lib_concepts
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 3435. three_way_comparable_with<reverse_iterator<int*>, [...]>
+ template<typename _Iter>
+ static constexpr bool __convertible = !is_same_v<_Iter, _Iterator>
+ && convertible_to<const _Iter&, _Iterator>;
+#endif
+
protected:
_Iterator current;
@@ -182,9 +195,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
* underlying %iterator can be converted to the type of @c current.
*/
template<typename _Iter>
+#if __cpp_lib_concepts
+ requires __convertible<_Iter>
+#endif
_GLIBCXX17_CONSTEXPR
reverse_iterator(const reverse_iterator<_Iter>& __x)
- : current(__x.base()) { }
+ : current(__x.current) { }
+
+#if __cplusplus >= 201103L
+ template<typename _Iter>
+#if __cpp_lib_concepts
+ requires __convertible<_Iter>
+ && assignable_from<_Iterator&, const _Iter&>
+#endif
+ _GLIBCXX17_CONSTEXPR
+ reverse_iterator&
+ operator=(const reverse_iterator<_Iter>& __x)
+ {
+ current = __x.current;
+ return *this;
+ }
+#endif
/**
* @return @c current, the %iterator used for underlying work.
@@ -1270,6 +1301,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
using __base_ref = typename __traits_type::reference;
#endif
+ template<typename _Iter2>
+ friend class move_iterator;
+
+#if __cpp_lib_concepts
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 3435. three_way_comparable_with<reverse_iterator<int*>, [...]>
+ template<typename _Iter2>
+ static constexpr bool __convertible = !is_same_v<_Iter2, _Iterator>
+ && convertible_to<const _Iter2&, _Iterator>;
+#endif
+
public:
using iterator_type = _Iterator;
@@ -1303,15 +1345,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: _M_current(std::move(__i)) { }
template<typename _Iter>
+#if __cpp_lib_concepts
+ requires __convertible<_Iter>
+#endif
_GLIBCXX17_CONSTEXPR
move_iterator(const move_iterator<_Iter>& __i)
- : _M_current(__i.base()) { }
+ : _M_current(__i._M_current) { }
template<typename _Iter>
+#if __cpp_lib_concepts
+ requires __convertible<_Iter>
+ && assignable_from<_Iterator&, const _Iter&>
+#endif
_GLIBCXX17_CONSTEXPR
move_iterator& operator=(const move_iterator<_Iter>& __i)
{
- _M_current = __i.base();
+ _M_current = __i._M_current;
return *this;
}
diff --git a/libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc b/libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc
new file mode 100644
index 00000000000..170d4977df1
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc
@@ -0,0 +1,37 @@
+// 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
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <iterator>
+#include <compare>
+
+// LWG 3435. three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>>
+// and
+// LWG 3265. move_iterator's conversions are more broken after P1207
+
+using RI = std::move_iterator<int*>;
+using CRI = std::move_iterator<const int*>;
+
+static_assert( std::three_way_comparable_with<RI, CRI> );
+
+static_assert( std::is_convertible_v<const RI&, CRI> );
+static_assert( ! std::is_convertible_v<const CRI&, RI> );
+
+static_assert( std::is_assignable_v<CRI, const RI&> );
+static_assert( ! std::is_assignable_v<RI, const CRI&> );
diff --git a/libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr3435.cc b/libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr3435.cc
new file mode 100644
index 00000000000..77b0f39c535
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr3435.cc
@@ -0,0 +1,36 @@
+// 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
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <iterator>
+#include <compare>
+
+// LWG 3435.
+// three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>>
+
+using RI = std::reverse_iterator<int*>;
+using CRI = std::reverse_iterator<const int*>;
+
+static_assert( std::three_way_comparable_with<RI, CRI> );
+
+static_assert( std::is_convertible_v<const RI&, CRI> );
+static_assert( ! std::is_convertible_v<const CRI&, RI> );
+
+static_assert( std::is_assignable_v<CRI, const RI&> );
+static_assert( ! std::is_assignable_v<RI, const CRI&> );
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