intersphinx broken

[crusaderky]

sphinx-autodoc-typehints is generating a huge amount of errors in my project that uses interphinx.

conf.py:

extensions = [
    "sphinx.ext.autodoc",
    "sphinx.ext.autosummary",
    "sphinx.ext.intersphinx",
    "sphinx_autodoc_typehints",
]

intersphinx_mapping = {
    "python": ("https://docs.python.org/3/", None),
    "xarray": ("https://xarray.pydata.org/en/stable/", None),
}

set_type_checking_flag = True
typehints_fully_qualified = False
always_document_param_types = True
typehints_document_rtype = True

hello.rst:

.. automodule:: myproject.hello
   :members:
   :undoc-members:
   :show-inheritance:

hello.py:

from typing import Union
import xarray

XarrayType = Union[xarray.DataArray, xarray.Dataset]

class C:
    x: XarrayType

    def __init__(self, x: XarrayType):
        self.x = x

sphinx-build output:

myproject/hello.py:docstring of myproject.hello.C:6: WARNING: py:class reference target not found: xarray.core.dataarray.DataArray
myproject/hello.py:docstring of myproject.hello.C:6: WARNING: py:class reference target not found: xarray.core.dataset.Dataset
myproject/hello.py:docstring of myproject.hello.C:8: WARNING: py:class reference target not found: xarray.core.dataarray.DataArray
myproject/hello.py:docstring of myproject.hello.C:8: WARNING: py:class reference target not found: xarray.core.dataset.Dataset

This is caused by sphinx_autodoct_typehints reading DataArray.__module__; however in the interstphinx objects.inv that is overridden by the module that lists the object in __all__:

$ python -msphinx.ext.intersphinx https://xarray.pydata.org/en/stable/objects.inv | grep '.DataArray '
        xarray.DataArray                         generated/xarray.DataArray.html#xarray.DataArray
        generated/xarray.DataArray               xarray.DataArray                        : generated/xarray.DataArray.html

$  python -c 'import xarray; print(xarray.DataArray.__module__)'
xarray.core.dataarray

This issue is triggered on all packages that define a class in an implementation script and then import it in __init__.py, e.g.:

impl.py:

class C:
    pass

__init__.py:

from .impl import C
__all__ = ("C", )

[agronholm]

What do you expect me to do about this?

[agronholm]

Looks like a duplicate of #38, yes?

[crusaderky]

Yes, it is