stubgen & pybind11: can we make them play nice(r)?

Bug Report
We're experimenting under https://github.com/pybind/pybind11/pull/4888 with a pybind11 behavior change, to generate

Annotated[Any, CppTypePybind11("cpp_namespace::UserType")]

instead of a bare cpp_namespace::UserType.

It seems like mypy does handle outer-level Annotated, but not nested ones, e.g.

Iterator[str, Annotated[Any, CppTypePybind11("cpp_namespace::UserType")]]

The results from stubgen (1.5.1, Google-internal toolchain) are like this:

def values(self, *args, **kwargs) -> Any: ...

Desired is:

def values(self) -> Iterator[str, Annotated[Any, CppTypePybind11("cpp_namespace::UserType")]]: ...

Does this ring any bells?

If you need more details, please let me know. (Note though that I don't know a lot about typing and mypy. This fell into my lap as Google-internal pybind11 owner & pybind11 maintainer on github.)

A more general question: What are your thought about changing the pybind11 behavior in this way? Is there a better way?

(A clear and concise description of what the bug is.)

To Reproduce

# Ideally, a small sample program that demonstrates the problem.
# Or even better, a reproducible playground link https://mypy-play.net/ (use the "Gist" button)

Expected Behavior

Actual Behavior

Your Environment

• Mypy version used: 1.5.1, Google-internal toolchain
• Mypy command-line flags:
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.10

The report names stubgen and shows a nested Annotated example, but no repository files or tests. Start by reproducing the behavior with the shown Python 3.10 example and stubgen 1.5.1, then trace where the signature becomes *args, **kwargs. Done means generated output preserves the nested Iterator and Annotated types as in the desired signature.