Impossible to properly document NamedTuple with attribute annotations

It's not possible to properly document NamedTuple with autodoc.

test.rst:

test module
===========

.. automodule:: test
   :members:
   :undoc-members:
   :show-inheritance:

test.py:

from typing import NamedTuple

class Foo(NamedTuple):
    """Description

    Attributes:
        foo: This shows the type properly, but gives a warning
    """

    foo: float

    bar: str # This doesn't show the type

    baz: int #: This also doesn't show the type

Results in:

and the error:

test.py:docstring of test.Foo.foo:1: WARNING: duplicate object description of test.Foo.foo, other instance in source/test, use :noindex: for one of them

1. foo: Documenting foo in Attributes and adding the type below (which is the preferred way of documenting this) results in a duplicate entry in the documentation as well as the duplicate object description error.
2. bar: Not documenting it shows neither type nor description
3. baz: Adding the description in an inline comment shows the description, but ignores the type of the variable.

Expected
I would expect 1) to remove the duplicate entry, and 2) and 3) to show the proper type automatically in the documentation.

Environment info

• OS: Mac
• Python version: [e.g. 3.7.1]
• Sphinx version: 3.4.3
• Sphinx extensions: "sphinx.ext.autodoc", "sphinx.ext.napoleon",
• napoleon_attr_annotations = True

Reproduce the report with test.rst and test.py using Sphinx 3.4.3, autodoc, napoleon, and napoleon_attr_annotations enabled. Start by tracing how autodoc renders the NamedTuple attributes and their annotations; done means the foo duplicate warning is removed and bar and baz show their types and descriptions as expected.