Allowed wait_socket_readable/writable to accept a file descriptor

[davidbrochart]

Changes

Fixes #821.

It seems that anyio.wait_socket_readable(sock) and anyio.wait_socket_writable(sock) can not only accept a socket.socket but also the socket's file descriptor (int):

• On asyncio, add_reader and add_writer accept a file descriptor.
• On trio, wait_readable and wait_writable accept a file descriptor or an object with a .fileno() method returning a file descriptor.

Checklist

If this is a user-facing code change, like a bugfix or a new feature, please ensure that
you've fulfilled the following conditions (where applicable):

• You've added tests (in tests/) added which would fail without your patch
• You've updated the documentation (in docs/, in case of behavior changes or new
  features)
• You've added a new changelog entry (in docs/versionhistory.rst).

[davidbrochart]

Not sure about the mypy error:

tests/test_sockets.py:1884: error: Argument 1 has incompatible type "object"; expected "socket | int"  [arg-type]

[agronholm]

You really should install pre-commit locally.

[agronholm]

The docs build is now failing due to the typeshed annotation. I don't remember off hand how I've dealt with this previously.

[davidbrochart]

I'm not sure why docs fails.

[agronholm]

The docs build is now failing due to the typeshed annotation. I don't remember off hand how I've dealt with this previously.

Ah, I remember now. Check out anyio._core._fileio to find out what I did about that.

[agronholm]

Please stop force pushing your changes. It makes the review process much harder.

[agronholm]

Let's use the proper Sphinx annotation for deprecations.

[agronholm]

One more thing: the new functions need to be added to the API documentation too.