Generic object attribute with contraints wrongly seen as TypeVar or Generic type in isinstance

[hojo0590]

Environment data

• Language Server version: 2021.8.3 (pyright fa4194fd)
• OS and version: Win10 19043.1165
• Python version (& distribution if applicable, e.g. Anaconda): 3.8.11 (Anaconda)

Code Snippet

from typing import Any, Generic, TypeVar

T = TypeVar("T", int, str)


class B(Generic[T]):
    att: T

    def check_type(self, var: Any) -> bool:
        return isinstance(var, type(self.att))

Expected behaviour

I'd expect pylance to not throw an Second argument to "isinstance" must be a class or tuple of classes TypeVar or generic type with type arguments not allowed error on the second argument passed to isisntance().

Actual behaviour

Error is thrown.

Additional information

Possibly related/in addition to #1294 and
using a TypeVar without constraints works well.

from typing import Any, Generic, TypeVar

T = TypeVar("T")


class B(Generic[T]):
    att: T

    def check_type(self, var: Any) -> bool:
        return isinstance(var, type(self.att))

(removing the constraints TypeVar("T", int, str) -> TypeVar("T") does not lead to an error)

[erictraut]

Thanks for the bug report. I agree this is a bug. It occurs only with a constrained TypeVar. The fix will be in the next release.

[jakebailey]

This issue has been fixed in version 2021.7.0, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/main/CHANGELOG.md#202190-1-september-2021