Segfault on inserting function into std::pmr container

[jwt27]

The following code causes a segfault:

std::pmr::deque<func::function<void()>> functions { };
func::function<void()> f { [] { } };
functions.push_back(f);

However, creating a single function with the pmr allocator does not:

func::function<void()> f { std::allocator_arg, std::pmr::polymorphic_allocator<> { }, [] { } };

And this also works:

functions.push_back([] { });

Possibly related to #2 somehow, but std::pmr::polymorphic_allocator has no virtual destructor.

[jwt27]

Digging into this, I see the allocator is only "stored" by reinterpret_casting the manager in manager_storage_type. Is that an oversight or deliberate? I suppose it works for stateless allocators but not if they have any contents (or vtables). Now I'm
questioning how some of my code ever worked at all.

I suppose the solution is to use the allocator to allocate space for itself, or just add a char[] block in manager_storage_type and static_assert that the allocator does not exceed that size.