https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96416
Bug ID: 96416
Summary: address_of() is broken by static_assert in
pointer_traits
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: whatwasthataddress at gmail dot com
Target Milestone: ---
pointer_traits contains this static_assert:
static_assert(!is_same<element_type, __undefined>::value,
"pointer type defines element_type or is like SomePointer<T, Args>");
When trying to use address_of() with an iterator that has a usable
operator->(), address_of() fails because the static_assert causes a hard error
in the trailing decltype here:
template<typename _Ptr>
constexpr auto
__to_address(const _Ptr& __ptr) noexcept
-> decltype(std::pointer_traits<_Ptr>::to_address(__ptr))
{ return std::pointer_traits<_Ptr>::to_address(__ptr); }
template<typename _Ptr, typename... _None>
constexpr auto
__to_address(const _Ptr& __ptr, _None...) noexcept
{
if constexpr (is_base_of_v<__gnu_debug::_Safe_iterator_base, _Ptr>)
return std::__to_address(__ptr.base().operator->());
else
return std::__to_address(__ptr.operator->());
}
When I comment out the static_assert, to_address() works with the iterator in
question.
