Error Message for methods that return Self for classes that are subclasses of other classes.

I have a class that inherits from another class (See below code snippet) with a __next__ method that returns Self. It threw the error:

error[E0277]: the trait bound `Child: pyo3::impl_::callback::IntoPyCallbackOutput<'_, _>` is not satisfied
   --> src/lib.rs:11:1
    |
 11 | #[pymethods]
    | ^^^^^^^^^^^^ unsatisfied trait bound
    |
help: the trait `pyo3::impl_::callback::IntoPyCallbackOutput<'_, _>` is not implemented for `Child`
   --> src/lib.rs:9:1
    |
  9 | struct Child(u64);
    | ^^^^^^^^^^^^
    = help: the following other types implement trait `pyo3::impl_::callback::IntoPyCallbackOutput<'py, Target>`:
              ...
note: required by a bound in `pyo3::impl_::pymethods::IterBaseTag::convert`
   --> .../src/impl_/pymethods.rs:473:16
    |
471 |     pub fn convert<'py, Value, Target>(self, py: Python<'py>, value: Value) -> PyResult<Target>
    |            ------- required by a bound in this associated function
472 |     where
473 |         Value: IntoPyCallbackOutput<'py, Target>,
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `IterBaseTag::convert`
    = note: this error originates in the attribute macro `pymethods` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0277`.
error: could not compile `example_py` (lib) due to 1 previous error

The fix was to have the method return Py::new(py, PyClassInitializer::from(Base).add_subclass(self.0)), but it would be nice to have the compiler error message report this.

Example code that threw the compile error:

#[pyclass(subclass)]
#[derive(Debug, Clone, Copy)]
struct Base;

#[pyclass(extends=Base, subclass)]
#[derive(Debug, Clone, Copy)]
struct Child(u64);

#[pymethods]
impl Child {
    #[new]
    fn new() -> PyClassInitializer<Self> {
        PyClassInitializer::from(Base).add_subclass(Self(0))
    }

    fn __next__(&mut self) -> Self {
        self.0 += 1;

        Self(self.0)
    }
}

Reproduce the example from src/lib.rs, then inspect the #[pymethods] expansion and src/impl_/pymethods.rs around IterBaseTag::convert and its IntoPyCallbackOutput bound. Trace how the Self return is diagnosed and add coverage for subclassed PyClasses; done means the compiler output explains the required wrapped return form instead of only reporting the trait bound.