[PATCH] libstdc++: Fix <ext/pointer.h> incompatibilities with C++20
Jonathan Wakely
jwakely@redhat.com
Fri Jan 10 08:02:00 GMT 2020
The equality operators for _ExtPtr_allocator are defined as non-const
member functions, which causes ambiguities in C++20 due to the
synthesized operator!= candidates. They should always have been const.
The _Pointer_adapter class template has both value_type and element_type
members, which makes readable_traits<_Pointer_adapter<T>> ambiguous. The
intended workaround is to add a specialization of readable_traits.
* include/ext/extptr_allocator.h (_ExtPtr_allocator::operator==)
(_ExtPtr_allocator::operator!=): Add missing const qualifiers.
* include/ext/pointer.h (readable_traits<_Pointer_adapter<S>>): Add
partial specialization to disambiguate the two constrained
specializations.
Tested powerpc64le-linux, committed to trunk.
-------------- next part --------------
commit fa14bee2f1a8b608fe8279f82d8697473eda0259
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Jan 9 20:58:18 2020 +0000
libstdc++: Fix <ext/pointer.h> incompatibilities with C++20
The equality operators for _ExtPtr_allocator are defined as non-const
member functions, which causes ambiguities in C++20 due to the
synthesized operator!= candidates. They should always have been const.
The _Pointer_adapter class template has both value_type and element_type
members, which makes readable_traits<_Pointer_adapter<T>> ambiguous. The
intended workaround is to add a specialization of readable_traits.
* include/ext/extptr_allocator.h (_ExtPtr_allocator::operator==)
(_ExtPtr_allocator::operator!=): Add missing const qualifiers.
* include/ext/pointer.h (readable_traits<_Pointer_adapter<S>>): Add
partial specialization to disambiguate the two constrained
specializations.
diff --git a/libstdc++-v3/include/ext/extptr_allocator.h b/libstdc++-v3/include/ext/extptr_allocator.h
index 933bdb69a51..88090548b7c 100644
--- a/libstdc++-v3/include/ext/extptr_allocator.h
+++ b/libstdc++-v3/include/ext/extptr_allocator.h
@@ -131,20 +131,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Up>
inline bool
- operator==(const _ExtPtr_allocator<_Up>& __rarg)
+ operator==(const _ExtPtr_allocator<_Up>& __rarg) const
{ return _M_real_alloc == __rarg._M_getUnderlyingImp(); }
inline bool
- operator==(const _ExtPtr_allocator& __rarg)
+ operator==(const _ExtPtr_allocator& __rarg) const
{ return _M_real_alloc == __rarg._M_real_alloc; }
template<typename _Up>
inline bool
- operator!=(const _ExtPtr_allocator<_Up>& __rarg)
+ operator!=(const _ExtPtr_allocator<_Up>& __rarg) const
{ return _M_real_alloc != __rarg._M_getUnderlyingImp(); }
inline bool
- operator!=(const _ExtPtr_allocator& __rarg)
+ operator!=(const _ExtPtr_allocator& __rarg) const
{ return _M_real_alloc != __rarg._M_real_alloc; }
template<typename _Up>
diff --git a/libstdc++-v3/include/ext/pointer.h b/libstdc++-v3/include/ext/pointer.h
index 84d530054e6..02d3e60169f 100644
--- a/libstdc++-v3/include/ext/pointer.h
+++ b/libstdc++-v3/include/ext/pointer.h
@@ -46,6 +46,9 @@
# include <bits/move.h>
# include <bits/ptr_traits.h>
#endif
+#if __cplusplus > 201703L
+# include <iterator> // for readable_traits
+#endif
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
@@ -594,6 +597,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return pointer(std::addressof(__r)); }
};
+#if __cpp_lib_concepts
+ template<typename _Storage_policy>
+ struct readable_traits<__gnu_cxx::_Pointer_adapter<_Storage_policy>>
+ {
+ using value_type
+ = typename __gnu_cxx::_Pointer_adapter<_Storage_policy>::value_type;
+ };
+#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif
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