https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96074
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
Status|ASSIGNED |RESOLVED
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Your test allocator has a bug. You do not override the is_always_equal trait
from the base class, which means you inherit std::allocator<T>::is_always_equal
which is defined to be std::true_type. So the associative containers elide the
propagation:
if (_Alloc_traits::_S_propagate_on_copy_assign())
{
auto& __this_alloc = this->_M_get_Node_allocator();
auto& __that_alloc = __x._M_get_Node_allocator();
if (!_Alloc_traits::_S_always_equal()
&& __this_alloc != __that_alloc)
{
// Replacement allocator cannot free existing storage, we
need
// to erase nodes first.
clear();
std::__alloc_on_copy(__this_alloc, __that_alloc);
}
}
If I add this to the primary template and the partial specialization then all
tests pass (including the commented-out one for std::stringbuf):
using is_always_equal = std::false_type;
You have been bitten by LWG 3170: https://cplusplus.github.io/LWG/issue3170
std::allocator<T>::is_always_equal is deprecated for precisely this reason
(it's a very annoying trap) but it's still there in C++20, so you need to
override it.
Closing, as the libstdc++ containers are already correct.
