Fixed singledispatch documentation

[jmp1985]

Subject: Single dispatch functions were not documented due to minor bug which this pull request fixes

Feature or Bugfix

• Bugfix
• Refactoring

Purpose

• Previously, singledispatch functions never had their variants documented. This bugfix results in the variants being documented.

Detail

Here is a minimal example package which shows the error:
bug_example.zip

Here is an old picture of the output:

Here is new picture of the output which is what I think is intended:

[tk0miya]

Could you add a testcase, please?

[jmp1985]

Hi @tk0miya. I would be happy to add a test case but would you be able to point me to an example test or template I could follow?

[tk0miya]

Please check these files:

• https://github.com/sphinx-doc/sphinx/blob/5.x/tests/test_ext_autodoc.py#L2063-L2127
• https://github.com/sphinx-doc/sphinx/blob/5.x/tests/roots/test-ext-autodoc/target/singledispatch.py
• https://github.com/sphinx-doc/sphinx/blob/5.x/tests/roots/test-ext-autodoc/target/singledispatchmethod.py

They confirms the result of autodoc for singledispatch functions and methods. I think this change should change (add?) something new to these testcases.

[jmp1985]

Thanks @tk0miya

I have added the test cases. It turned out that with single dispatch if you register the variants as follows everything works fine:

@func.register(int)
def func_int(arg):
    pass

However, if you use type annotations as follows then sphinx would not work:

@func.register
def func_int(arg: int):
    pass

This pull request now fixes this behaviour and adds a test case for functions registered using type annotations.

[tk0miya]

Thank you for your update. I don't know singledispatch now supports type annotated functions and methods.
https://docs.python.org/3/library/functools.html#functools.singledispatch

LGTM!

[tk0miya]

Merged. Thank you for your contribution!