pybind11 will downcast is stead of using overload resolution resulting in unexpected behavior

Coming from C++ I expected overload resolution to be maintained through pybind11. This is not the case. I dont know if it is not possible to implement in pybind11. If that is the case, It could be (more) clearly stated in the documentation, and a feature request would be that the overload function priority could be explicitly given.

An example:

#include <pybind11/pybind11.h>

namespace py = pybind11;

class A
{
public:
    A(int v_) : v{ v_ } {}
    int val() const { return v; }
    void val(int i) { v = i; }
private:
    int v = 0;
};

class B: public A
{
public:
    B(int v) : A{ v-1 } {}
    int val() const { return A::val() + 1; }
    void val(int i) { A::val(i-1); }
};

template <typename T>
T& f(T& t, int i) { t.val(i); return t; }

PYBIND11_MODULE(pyreftest, m) {
    py::class_<A>(m, "A")
        .def(py::init<int>())
        .def("__repr__", [](const A&a) {return "<A(" + std::to_string(a.val()) + ")>";  });
    py::class_<B,A>(m, "B")
        .def(py::init<int>())
        .def("__repr__", [](const B&b) {return "<B(" + std::to_string(b.val()) + ")>";  });
    m.def("f", &f<A>);
    m.def("f", &f<B>);
}

Result:

In [1]: from pyreftest import *

In [2]: b = B(3)

In [3]: b
Out[3]: <B(3)>

In [4]: f(b,4)
Out[4]: <A(4)>

In [5]: b
Out[5]: <B(5)>

Expected result:

In [1]: from pyreftest import *

In [2]: b = B(3)

In [3]: b
Out[3]: <B(3)>

In [4]: f(b,4)
Out[4]: <B(4)>

In [5]: b
Out[5]: <B(4)>

I realize that a workaround is to swap the two last lines of code i.e:

    m.def("f", &f<B>);
    m.def("f", &f<A>);

but I think this is more a workaround than a fix.

Otherwise awesome project
Best regards Troels

Start with the supplied pyreftest reproducer and the two m.def("f", ...) registrations, then inspect how overload resolution handles A and B arguments. Done would be a confirmed behavior with either an implementation and regression test or clear documentation of the limitation and the registration-order workaround.