From 807ad4bc854caea407aaa09993e4a3220290b0f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Dumont?= <fdumont@gcc.gnu.org>
Date: Wed, 6 Oct 2021 06:55:19 +0200
Subject: [PATCH] libstdc++: Overload std::__to_address for
__gnu_cxx::__normal_iterator.
Prefer to overload __to_address to partially specialize std::pointer_traits because
std::pointer_traits would be mostly useless. Moreover partial specialization of
pointer_traits<__normal_iterator<P, C>> fails to rebind C, so you get incorrect types
like __normal_iterator<long*, vector<int>>. In the case of __gnu_debug::_Safe_iterator
the to_pointer method is impossible to implement correctly because we are missing
the parent container to associate the iterator to.
libstdc++-v3/ChangeLog:
* include/bits/stl_iterator.h
(std::pointer_traits<__gnu_cxx::__normal_iterator<>>): Remove.
(std::__to_address(const __gnu_cxx::__normal_iterator<>&)): New for C++11 to C++17.
* include/debug/safe_iterator.h
(std::__to_address(const __gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<>,
_Sequence>&)): New for C++11 to C++17.
* testsuite/24_iterators/normal_iterator/to_address.cc: Add check on std::vector::iterator
to validate both __gnu_cxx::__normal_iterator<> __to_address overload in normal mode and
__gnu_debug::_Safe_iterator in _GLIBCXX_DEBUG mode.
---
libstdc++-v3/include/bits/stl_iterator.h | 32 +++++--------------
libstdc++-v3/include/debug/safe_iterator.h | 17 ++++++++++
.../normal_iterator/to_address.cc | 17 ++++++++--
3 files changed, 40 insertions(+), 26 deletions(-)
diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index 6bd860b803eb..ac9342112f40 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -1349,32 +1349,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#if __cplusplus >= 201103L
- // Need to specialize pointer_traits because the primary template will
- // deduce element_type of __normal_iterator<T*, C> as T* rather than T.
+#if __cplusplus <= 201703L
+ // Need to overload __to_address because the pointer_traits primary template
+ // will deduce element_type of __normal_iterator<T*, C> as T* rather than T.
template<typename _Iterator, typename _Container>
- struct pointer_traits<__gnu_cxx::__normal_iterator<_Iterator, _Container>>
- {
- private:
- using _Base = pointer_traits<_Iterator>;
-
- public:
- using element_type = typename _Base::element_type;
- using pointer = __gnu_cxx::__normal_iterator<_Iterator, _Container>;
- using difference_type = typename _Base::difference_type;
-
- template<typename _Tp>
- using rebind = __gnu_cxx::__normal_iterator<_Tp, _Container>;
-
- static pointer
- pointer_to(element_type& __e) noexcept
- { return pointer(_Base::pointer_to(__e)); }
-
-#if __cplusplus >= 202002L
- static element_type*
- to_address(pointer __p) noexcept
- { return __p.base(); }
+ constexpr auto
+ __to_address(const __gnu_cxx::__normal_iterator<_Iterator,
+ _Container>& __it) noexcept
+ -> decltype(std::__to_address(__it.base()))
+ { return std::__to_address(__it.base()); }
#endif
- };
/**
* @addtogroup iterators
diff --git a/libstdc++-v3/include/debug/safe_iterator.h b/libstdc++-v3/include/debug/safe_iterator.h
index 5584d06de5a6..9c821c82e174 100644
--- a/libstdc++-v3/include/debug/safe_iterator.h
+++ b/libstdc++-v3/include/debug/safe_iterator.h
@@ -1013,6 +1013,23 @@ namespace __gnu_debug
} // namespace __gnu_debug
+#if __cplusplus >= 201103L && __cplusplus <= 201703L
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+ template<typename _Iterator, typename _Container, typename _Sequence>
+ constexpr auto
+ __to_address(const __gnu_debug::_Safe_iterator<
+ __gnu_cxx::__normal_iterator<_Iterator, _Container>,
+ _Sequence>& __it) noexcept
+ -> decltype(std::__to_address(__it.base().base()))
+ { return std::__to_address(__it.base().base()); }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+}
+#endif
+
#undef _GLIBCXX_DEBUG_VERIFY_DIST_OPERANDS
#undef _GLIBCXX_DEBUG_VERIFY_REL_OPERANDS
#undef _GLIBCXX_DEBUG_VERIFY_EQ_OPERANDS
diff --git a/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc b/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc
index 510d627435fa..6afc6540609c 100644
--- a/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc
+++ b/libstdc++-v3/testsuite/24_iterators/normal_iterator/to_address.cc
@@ -1,6 +1,19 @@
// { dg-do compile { target { c++11 } } }
#include <string>
+#include <vector>
#include <memory>
-char* p = std::__to_address(std::string("1").begin());
-const char* q = std::__to_address(std::string("2").cbegin());
+#include <testsuite_allocator.h>
+
+char* p __attribute__((unused))
+ = std::__to_address(std::string("1").begin());
+const char* q __attribute__((unused))
+ = std::__to_address(std::string("2").cbegin());
+int* r __attribute__((unused))
+ = std::__to_address(std::vector<int>(1, 1).begin());
+const int* s __attribute__((unused))
+ = std::__to_address(std::vector<int>(1, 1).cbegin());
+int* t __attribute__((unused))
+ = std::__to_address(std::vector<int, __gnu_test::CustomPointerAlloc<int>>(1, 1).begin());
+const int* u __attribute__((unused))
+ = std::__to_address(std::vector<int, __gnu_test::CustomPointerAlloc<int>>(1, 1).cbegin());
--
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