Bug Report

If a NamedTuple is generic over T, then for some reason, inside a match statement over this NamedTuple, all information about member variables and their types are erased. Even if they are explicitly stated.

To Reproduce

from typing import NamedTuple

class Wrapper[T](NamedTuple):
    wrap: T


foo: Wrapper[int] = Wrapper(123)

def bar() -> int:
    match foo:
        case Wrapper(wrap=w):
            return w
        case _:  # this is only to make this error-less with `pyrefly`
            raise RuntimeError("Unreachable")

Expected Behavior

This function clearly matches a Wrapper[int] in its first case. It should detect it can match the internal wrap variable, and it also has to be int.

$ pyrefly check tst.py
 INFO 0 errors
$ pyright tst.py
0 errors, 0 warnings, 0 informations

Actual Behavior

mypy for some reason seems to say that Wrapper does not even have a wrap attribute, and also, it's saying that this is Any, even though the matched Wrapper here is Wrapper[int].

$ mypy --strict tst.py
tst.py:12: error: Class "tst.Wrapper[Any]" has no attribute "wrap"  [misc]
tst.py:13: error: Returning Any from function declared to return "int"  [no-any-return]

Your Environment

• Mypy version used: 1.19.1
• Mypy command-line flags: --strict
• Python version used: 3.12.9