Intellisense support for magic methods when using complex generic types

[girip11]

This pylance feature request is based on the discussion captured in the issue

Consider the below snippet.

# python 3.11 snippet
from typing import Any, Generic, Literal, TypeAlias, TypeVar

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

DS1FieldNames = Literal["col1", "col2", "col3"]

class GenericType(Generic[T]):
    def locate(self, value: T | list[T]) -> None:
        pass

    def __getattr__(self, value: T) -> Any:
        pass

    def __getitem__(self, value: T | list[T]) -> Any:
        pass

ConcreteType: TypeAlias = GenericType[DS1FieldNames]
c = ConcreteType()

Intellisense WORKS WELL when I type c.locate("") as well as c.locate([""]). Refer the image below.

Here are my feature requests with Intellisense support for the magic methods.

• Intellisense works with __getattr__ when the type parameter is explicitly coded. But it currently doesn't support generic type parameters. This will be very useful to restrict the possible attributes that can be called on a particular type.

• And the magic method __getitem__ currently supports generic type, but it doesn't support a signature like the one given in the above example. As discussed in the issue Unable to autosuggest members with typing.Literal types when used in Generic classes #4938, I am adding this to the feature request.

• It will be great, in general if the Intellisense could work for other magic methods like __setitem__, __setattr__ with generic types.

[debonte]

Moving this issue to discussion as an enhancement request for comments and upvotes.