Update list.{count, index, remove} to accept object type

stdlib/@tests/test_cases/builtins/check_list.py

@@ -19,3 +19,12 @@ def asd(self) -> int:
 assert_type(combined, List[Union[Foo, Bar]])
 for item in combined:
     assert_type(item.asd(), int)
+
+
+def test_list_signature_overlapping_type(l: list[int], key: float) -> None:
+    # list.{index, count, remove} allow any type for the key since
+    # (a) the key may overlap with the list's element type, and
+    # (b) these methods are equality-based anyway.
+    l.index(key)
+    l.count(key)
+    l.remove(key)

stdlib/builtins.pyi

@@ -1235,10 +1235,10 @@ class list(MutableSequence[_T]):
     def pop(self, index: SupportsIndex = -1, /) -> _T: ...
     # Signature of `list.index` should be kept in line with `collections.UserList.index()`
     # and multiprocessing.managers.ListProxy.index()
-    def index(self, value: _T, start: SupportsIndex = 0, stop: SupportsIndex = sys.maxsize, /) -> int: ...
-    def count(self, value: _T, /) -> int: ...
+    def index(self, value: object, start: SupportsIndex = 0, stop: SupportsIndex = sys.maxsize, /) -> int: ...
+    def count(self, value: object, /) -> int: ...
     def insert(self, index: SupportsIndex, object: _T, /) -> None: ...
-    def remove(self, value: _T, /) -> None: ...
+    def remove(self, value: object, /) -> None: ...
 
     # Signature of `list.sort` should be kept inline with `collections.UserList.sort()`
     # and multiprocessing.managers.ListProxy.sort()

stubs/boltons/boltons/listutils.pyi

@@ -20,8 +20,8 @@ class BarrelList(list[_T]):
     def __setslice__(self, start: SupportsIndex, stop: SupportsIndex, sequence: Iterable[_T]) -> None: ...
     def sort(self) -> None: ...  # type: ignore[override]
     def reverse(self) -> None: ...
-    def count(self, item: _T) -> int: ...
-    def index(self, item: _T) -> int: ...  # type: ignore[override]
+    def count(self, item: object) -> int: ...
+    def index(self, item: object) -> int: ...  # type: ignore[override]
 
 BList: TypeAlias = BarrelList[_T]