#include <stdio.h>
#include <list>
#include <memory>

#include <pybind11/pybind11.h>
#include <pybind11/stl.h>

struct B;

struct A {
    A() {};
    ~A() {
        printf("~A()\n");
        if (!b_list.empty()) {
            printf("b_list not empty!\n");
        }
    };

    void register_b(B *b) {
        b_list.push_back(b);
    };
    void unregister_b(B *b) {
        auto removed = std::remove(b_list.begin(), b_list.end(), b);
        b_list.erase(removed, b_list.end());
    };

    std::list<B *> b_list;
};

struct B {
    B(A& a) : m_a(a) {
        m_a.register_b(this);
    };
    ~B() {
        printf("~B()\n");
        m_a.unregister_b(this);
    };

    A& m_a;
};

namespace py = pybind11;
PYBIND11_MODULE(example, m) {
	py::class_<B>(m, "B");
	py::class_<A>(m, "A")
	    .def(py::init<>())
	    .def("get_b_list", [](A& _this) ->  std::vector<B> {
			std::vector<B> b_vec;
			b_vec.push_back({_this});
			b_vec.push_back({_this});
			return b_vec;
#if 1 // Switch between implementation described in the issue
    });
#else
    }, py::return_value_policy::move, py::keep_alive<0, 1>());
#endif
}