Make weakref.finalize generic per todo comment

stdlib/weakref.pyi

@@ -124,7 +124,7 @@ class WeakKeyDictionary(MutableMapping[_KT, _VT]):
         @overload
         def __ior__(self: Self, other: Iterable[tuple[_KT, _VT]]) -> Self: ...
 
-class finalize:  # TODO: This is a good candidate for to be a `Generic[_P, _T]` class
+class finalize:
     def __init__(self, __obj: object, __func: Callable[_P, Any], *args: _P.args, **kwargs: _P.kwargs) -> None: ...
     def __call__(self, _: Any = ...) -> Any | None: ...
     def detach(self) -> tuple[Any, Any, tuple[Any, ...], dict[str, Any]] | None: ...

test_cases/stdlib/test_weakref.py

@@ -0,0 +1,21 @@
+from typing import Any, Callable, Dict, Optional, Tuple
+from typing_extensions import TypeAlias, assert_type
+from weakref import finalize
+
+_ResultStructure: TypeAlias = Optional[Tuple[str, Callable[[int, int], int], Tuple[Any, ...], Dict[str, Any]]]
+
+
+class TObj:
+    """_T type var in stubs"""
+
+    pass
+
+
+def callback(x: int, y: int) -> int:
+    return x + y
+
+
+final = finalize(TObj, callback, 1, y=2)
+assert_type(final.peek(), _ResultStructure)
+assert_type(final.detach(), _ResultStructure)
+assert_type(final(), int | None)