Type unknown when instantiating type of TypeVar or Union

[cdce8p]

Environment data

• Language Server version: 2021.6.1
• OS and version: darwin x64
• Python version: 3.10.0b2
• python.analysis.indexing: undefined
• python.analysis.typeCheckingMode: basic

Code Snippet

from typing import TypeVar

class A: ...
class B: ...

T = TypeVar("T", A, B)

def func(cls: type[T]) -> T:
    instance1 = cls()
    reveal_type(instance1)  # Unknown
    return instance1


def func2(cls: type[A | B]) -> A | B:
    instance2 = cls()
    reveal_type(instance2)  # Unknown
    return instance2

Expected behaviour

instance1: T
instance2: A | B

The mypy output

test.py:10: note: Revealed type is "test.A"
test.py:10: note: Revealed type is "test.B"
test.py:16: note: Revealed type is "Union[test.A, test.B]"

Actual behaviour

Both, instance1 and instance2, are unknown.

Logs

--

[erictraut]

Thanks for the feature request. The type checker currently works with type[A] | type[B], but I agree that it should also work with type[A | B] and type[T].

[erictraut]

This will be addressed in the next release.

[bschnurr]

This issue has been fixed in version 2021.6.2, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/main/CHANGELOG.md#202162-16-june-2021