Use return_value_policy::reference for virtual method calls only

Author: rhaschke

include/pybind11/pybind11.h

@@ -2243,7 +2243,7 @@ template <class T> function get_override(const T *this_ptr, const char *name) {
         pybind11::gil_scoped_acquire gil; \
         pybind11::function override = pybind11::get_override(static_cast<const cname *>(this), name); \
         if (override) { \
-            auto o = override(__VA_ARGS__); \
+            auto o = override.operator()<py::return_value_policy::reference>(__VA_ARGS__); \
             if (pybind11::detail::cast_is_temporary_value_reference<ret_type>::value) { \
                 static pybind11::detail::override_caster_t<ret_type> caster; \
                 return pybind11::detail::cast_ref<ret_type>(std::move(o), caster); \

include/pybind11/pytypes.h

@@ -105,9 +105,9 @@ class object_api : public pyobject_tag {
         function will throw a `cast_error` exception. When the Python function
         call fails, a `error_already_set` exception is thrown.
     \endrst */
-    template <return_value_policy policy = return_value_policy::reference, typename... Args>
+    template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
     object operator()(Args &&...args) const;
-    template <return_value_policy policy = return_value_policy::reference, typename... Args>
+    template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
     PYBIND11_DEPRECATED("call(...) was deprecated in favor of operator()(...)")
         object call(Args&&... args) const;