Dataclass field that contains a descriptor object isn't handled correctly

[erictraut]

If a @dataclass field is initialized with a descriptor as a default value, pyright should use the value type of the __set__ method for the descriptor when determining the type of the corresponding parameter within the synthesized __init__ method.

Types are also evaluated incorrectly in this case.

Note that mypy also exhibits these same bugs.

from dataclasses import dataclass
from typing import Any, cast


class MyDescriptor:
    def __get__(self, __obj: object | None, __owner: Any) -> "int | MyDescriptor":
        if __obj is None:
            return self
        return cast(Any, __obj)._x

    def __set__(self, __obj: object | None, __value: int) -> None:
        if __obj is not None:
            cast(Any, __obj)._x = __value


@dataclass
class Foo:
    y: MyDescriptor = MyDescriptor()


f = Foo(3)  # Currently a false positive error in pyright (and mypy)

print(f.y)  # 3
f.y = 4
print(f.y)  # 4
print(Foo.y)  # MyDescriptor object

reveal_type(f.y) # int | MyDescriptor, which is wrong
reveal_type(Foo.y) # int | MyDescriptor, which is wrong

[erictraut]

This will be addressed in the next release.

[erictraut]

This is addressed in pyright 1.1.234, which I just published. It will also be included in the next pylance release.