Allow item to be passed as a keyword argument to UserList.index() again

stdlib/collections/__init__.pyi

@@ -137,9 +137,12 @@ class UserList(MutableSequence[_T]):
     def copy(self) -> Self: ...
     def __copy__(self) -> Self: ...
     def count(self, item: _T) -> int: ...
-    # The runtime signature is "item, *args", and the arguments are then passed
-    # to `list.index`. In order to give more precise types, we pretend that the
-    # `item` argument is positional-only.
+    # All arguments are passed to `list.index` at runtime,
+    # *but* `item` can be passed as a keyword-only parameter in `UserList.index()`
+    # *if* neither `start` nor `stop` are provided
+    @overload
+    def index(self, *, item: _T) -> int: ...
+    @overload
     def index(self, item: _T, start: SupportsIndex = 0, stop: SupportsIndex = sys.maxsize, /) -> int: ...
     # All arguments are passed to `list.sort` at runtime, so the signature should be kept in line with `list.sort`.
     @overload

tests/stubtest_allowlists/py310.txt

@@ -4,7 +4,6 @@ asyncio.base_events.BaseEventLoop.subprocess_exec # BaseEventLoop adds several p
 builtins.float.__setformat__  # Internal method for CPython test suite
 builtins.property.__set_name__  # Doesn't actually exist
 bz2.BZ2Decompressor.__init__  # function does not accept parameters but C signature is set
-collections\.UserList\.index  # ignoring pos-or-keyword parameter
 configparser.ParsingError.filename
 contextlib.AbstractAsyncContextManager.__class_getitem__
 contextlib.AbstractContextManager.__class_getitem__

tests/stubtest_allowlists/py311.txt

@@ -8,7 +8,6 @@ _csv.Writer
 bz2.BZ2Decompressor.__init__  # function does not accept parameters but C signature is set
 configparser.LegacyInterpolation.__init__
 configparser.ParsingError.filename
-collections\.UserList\.index  # ignoring pos-or-keyword parameter
 enum.Enum.__init__
 enum.Enum._generate_next_value_
 # Not strictly speaking a staticmethod on 3.11, but it acts like one:

tests/stubtest_allowlists/py312.txt

@@ -63,7 +63,6 @@ _weakref.ProxyType.__reversed__  # Doesn't really exist
 argparse._MutuallyExclusiveGroup.add_mutually_exclusive_group  # deprecated, forwards arguments to super
 ast.ImportFrom.level  # None on the class, but never None on instances
 builtins.property.__set_name__  # Doesn't actually exist
-collections\.UserList\.index  # ignoring pos-or-keyword parameter
 dataclasses.KW_ONLY  # white lies around defaults
 enum.auto.__init__  # The stub for enum.auto is nothing like the implementation
 enum.auto.value  # The stub for enum.auto is nothing like the implementation

tests/stubtest_allowlists/py3_common.txt

@@ -25,6 +25,7 @@ asyncio.Future.__init__  # Usually initialized from c object
 asyncio.futures.Future.__init__  # Usually initialized from c object
 builtins.dict.get
 collections\.ChainMap\.fromkeys  # https://github.com/python/mypy/issues/17023
+collections\.UserList\.index  # ignoring pos-or-keyword parameter
 collections\.UserList\.sort  # Runtime has *args but will error if any are supplied
 configparser.SectionProxy.__getattr__  # SectionProxy can have arbitrary attributes when custom converters are used
 # SectionProxy get functions are set in __init__