Does not allow popping from a TypedDict

[JelleZijlstra]

Describe the Bug

For this program:

from typing import ReadOnly, TypedDict, NotRequired

class TD(TypedDict):
    x: NotRequired[int]
    
def f(td: TD):
    td.pop("x")

Pyrefly (playground as of just now) reports:

ERROR 7:12-15: Argument `Literal['x']` is not assignable to parameter `k` with type `Never` in function `typing._TypedDict.pop` [[bad-argument-type](https://pyrefly.org/en/docs/error-kinds/#bad-argument-type)]

Other type checkers allow this, correctly in my view. I just reported bugs to mypy (python/mypy#19130) and pyright (microsoft/pyright#10489) where they fail to reject .pop when combined with ReadOnly, so I was curious what pyrefly did. It passes that test case but also rejects .pop in all other cases, which is incorrect.

Sandbox Link

https://pyrefly.org/sandbox/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoBKApgIYAmA8igDZwA0UAKokWQCJIDGMDAcmDGIBHAK5IQrAFCTO1EgGd5TNgApmCVh24BKAFySohqAA9dUfoKKjxrANqoYAXQNHJZIsCjAVMMmcZsei6GvgB0OAgqAETGUdpAA

(Only applicable for extension issues) IDE Information

No response

[yangdanny97]

Thanks for reporting! We do not have any special handling for methods on TypedDicts right now, but we'll keep ReadOnly semantics in mind when we do get around to supporting it.

[migeed-z]

fixed