[committed] libstdc++: Fix missing subsumption in std::iterator_traits [PR 97935]
Jonathan Wakely
jwakely@redhat.com
Wed Nov 25 17:41:44 GMT 2020
libstdc++-v3/ChangeLog:
PR libstdc++/97935
* include/bits/iterator_concepts.h (__detail::__iter_without_category):
New helper concept.
(__iterator_traits::__cat): Use __detail::__iter_without_category.
* testsuite/24_iterators/associated_types/iterator.traits.cc: New test.
Tested powerpc64le-linux. Committed to trunk.
I'll backport this to gcc-10 too.
-------------- next part --------------
commit 9d908b7fc475b351622fa5630d4874068c789d70
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Wed Nov 25 17:18:44 2020
libstdc++: Fix missing subsumption in std::iterator_traits [PR 97935]
libstdc++-v3/ChangeLog:
PR libstdc++/97935
* include/bits/iterator_concepts.h (__detail::__iter_without_category):
New helper concept.
(__iterator_traits::__cat): Use __detail::__iter_without_category.
* testsuite/24_iterators/associated_types/iterator.traits.cc: New test.
diff --git a/libstdc++-v3/include/bits/iterator_concepts.h b/libstdc++-v3/include/bits/iterator_concepts.h
index 8ff4f8667dd1..6668caa8185c 100644
--- a/libstdc++-v3/include/bits/iterator_concepts.h
+++ b/libstdc++-v3/include/bits/iterator_concepts.h
@@ -357,6 +357,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Iter>
concept __iter_without_nested_types = !__iter_with_nested_types<_Iter>;
+
+ template<typename _Iter>
+ concept __iter_without_category
+ = !requires { typename _Iter::iterator_category; };
+
} // namespace __detail
template<typename _Iterator>
@@ -396,20 +401,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ using type = typename _Iter::iterator_category; };
template<typename _Iter>
- requires (!requires { typename _Iter::iterator_category; }
- && __detail::__cpp17_randacc_iterator<_Iter>)
+ requires __detail::__iter_without_category<_Iter>
+ && __detail::__cpp17_randacc_iterator<_Iter>
struct __cat<_Iter>
{ using type = random_access_iterator_tag; };
template<typename _Iter>
- requires (!requires { typename _Iter::iterator_category; }
- && __detail::__cpp17_bidi_iterator<_Iter>)
+ requires __detail::__iter_without_category<_Iter>
+ && __detail::__cpp17_bidi_iterator<_Iter>
struct __cat<_Iter>
{ using type = bidirectional_iterator_tag; };
template<typename _Iter>
- requires (!requires { typename _Iter::iterator_category; }
- && __detail::__cpp17_fwd_iterator<_Iter>)
+ requires __detail::__iter_without_category<_Iter>
+ && __detail::__cpp17_fwd_iterator<_Iter>
struct __cat<_Iter>
{ using type = forward_iterator_tag; };
diff --git a/libstdc++-v3/testsuite/24_iterators/associated_types/iterator.traits.cc b/libstdc++-v3/testsuite/24_iterators/associated_types/iterator.traits.cc
new file mode 100644
index 000000000000..c3549fefaf60
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/associated_types/iterator.traits.cc
@@ -0,0 +1,56 @@
+// 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>
+
+struct bidi_iterator
+{
+ // No nested reference and pointer types.
+ // No iterator_category.
+
+ // cpp17-iterator requirements:
+ int& operator*() const;
+ bidi_iterator& operator++();
+ bidi_iterator operator++(int);
+
+ // cpp17-input-iterator requirements:
+ friend bool operator==(const bidi_iterator&, const bidi_iterator&);
+ using difference_type = long long;
+ using value_type = int;
+
+ // cpp17-forward-iterator requirements:
+ bidi_iterator();
+
+ // cpp17-bidirectional-iterator requirements:
+ bidi_iterator& operator--();
+ bidi_iterator operator--(int);
+};
+
+void
+test01()
+{
+ // PR libstdc++/97935
+ // Missing subsumption in iterator category detection
+ using namespace std;
+ static_assert(__detail::__cpp17_bidi_iterator<bidi_iterator>);
+ static_assert(same_as<iterator_traits<bidi_iterator>::iterator_category,
+ bidirectional_iterator_tag>,
+ "PR libstdc++/97935");
+}
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