[Downgrade] - Returning self no longer has proper type annotations

[iann838]

Today I noticed something is wrong with the annotation of codes, lot of codes and variables are marked as Any (white color), I have iterated the possible cause of this can it was due to return self in an async method defined in parent classes. It does not annotate properly self when it is extended, it keeps annotating self as the parent class. See image:

Note: this only happens to async methods, non-async methods works as expected.

Environment data

Language server version: 2021.10.0
Pylance version: v2021.10.0
Python version: 3.8.7
OS: win10

Expected behaviour

Variable o in image is annotated as B instead of ~A

Actual behaviour

Variable o in image is annotated as ~A

Impact potential

it basically disables the ability of autocompletion after using a parent defined async method returning self, because it is annotated as the parent class, it does not have access to extended class attributes.

Code snippet of the image

class A:

    async def get(self):
        return self


class B(A):
    pass


async def run():
    o = await B().get()
    o

Temporary Fix

EDIT: Downgrading Pylance to version v2021.9.4 fixes this aswell. Peraphs the easiest fix

from typing import TypeVar

Self = TypeVar('Self')

class A:

    async def get(self: Self) -> Self:
        return self

This does not justify as a "expected behavior", it functions with normal python methods but not coroutine methods

[iann838]

I have edited the issue, but it might not be visible enough, adding it here:
Downgrading Pylance to version v2021.9.4 fixes this aswell. Peraphs the easiest fix

[erictraut]

Thanks for the bug report. I've created a tracking bug in the pyright repo, and I'll investigate further.

[erictraut]

This will be fixed in the next release.

[iann838]

@erictraut Thanks, may I know when will next release be ? Will close after I update the version and check the bug is fixed

[erictraut]

We release pylance weekly, typically on Wednesdays.

We'll close the issue once the new version is published.

[bschnurr]

This issue has been fixed in version 2021.10.1, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/main/CHANGELOG.md#2021101-14-october-2021