multiprocessing.managers: fix TypeVar usage (#7938)

#7928

`dict()` and `list()` just return empty dictionaries and lists (respectively) if no arguments are supplied:

```python
>>> from multiprocessing.managers import SyncManager
>>> with SyncManager() as s:
...     print(s.dict())
...
{}
```

stdlib/builtins.pyi

@@ -871,11 +871,16 @@ class list(MutableSequence[_T], Generic[_T]):
     def extend(self, __iterable: Iterable[_T]) -> None: ...
     def pop(self, __index: SupportsIndex = ...) -> _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 = ..., __stop: SupportsIndex = ...) -> int: ...
     def count(self, __value: _T) -> int: ...
     def insert(self, __index: SupportsIndex, __object: _T) -> None: ...
     def remove(self, __value: _T) -> None: ...
     # Signature of `list.sort` should be kept inline with `collections.UserList.sort()`
+    # and multiprocessing.managers.ListProxy.sort()
+    #
+    # Use list[SupportsRichComparisonT] for the first overload rather than [SupportsRichComparison]
+    # to work around invariance
     @overload
     def sort(self: list[SupportsRichComparisonT], *, key: None = ..., reverse: bool = ...) -> None: ...
     @overload
@@ -908,6 +913,7 @@ class list(MutableSequence[_T], Generic[_T]):
 
 class dict(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
     # __init__ should be kept roughly in line with `collections.UserDict.__init__`, which has similar semantics
+    # Also multiprocessing.managers.SyncManager.dict()
     @overload
     def __init__(self) -> None: ...
     @overload

stdlib/multiprocessing/managers.pyi

@@ -1,12 +1,11 @@
 import queue
 import sys
 import threading
-from _typeshed import Self
-from builtins import dict as _dict, list as _list  # Conflicts with method names
-from collections.abc import Callable, Iterable, Mapping, Sequence
+from _typeshed import Self, SupportsKeysAndGetItem, SupportsRichComparison, SupportsRichComparisonT
+from collections.abc import Callable, Iterable, Iterator, Mapping, MutableMapping, MutableSequence, Sequence
 from types import TracebackType
-from typing import Any, AnyStr, Generic, TypeVar
-from typing_extensions import TypeAlias
+from typing import Any, AnyStr, ClassVar, Generic, TypeVar, overload
+from typing_extensions import SupportsIndex, TypeAlias
 
 from .connection import Connection
 from .context import BaseContext
@@ -66,6 +65,62 @@ class ValueProxy(BaseProxy, Generic[_T]):
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, item: Any) -> GenericAlias: ...
 
+class DictProxy(BaseProxy, MutableMapping[_KT, _VT]):
+    __builtins__: ClassVar[dict[str, Any]]
+    def __len__(self) -> int: ...
+    def __getitem__(self, __k: _KT) -> _VT: ...
+    def __setitem__(self, __k: _KT, __v: _VT) -> None: ...
+    def __delitem__(self, __v: _KT) -> None: ...
+    def __iter__(self) -> Iterator[_KT]: ...
+    def copy(self) -> dict[_KT, _VT]: ...
+    @overload
+    def get(self, __key: _KT) -> _VT | None: ...
+    @overload
+    def get(self, __key: _KT, __default: _VT | _T) -> _VT | _T: ...
+    @overload
+    def pop(self, __key: _KT) -> _VT: ...
+    @overload
+    def pop(self, __key: _KT, __default: _VT | _T) -> _VT | _T: ...
+    def keys(self) -> list[_KT]: ...  # type: ignore[override]
+    def values(self) -> list[tuple[_KT, _VT]]: ...  # type: ignore[override]
+    def items(self) -> list[_VT]: ...  # type: ignore[override]
+    if sys.version_info < (3, 7):
+        def has_key(self, k: _KT) -> bool: ...
+
+class BaseListProxy(BaseProxy, MutableSequence[_T]):
+    __builtins__: ClassVar[dict[str, Any]]
+    def __len__(self) -> int: ...
+    def __add__(self, __x: list[_T]) -> list[_T]: ...
+    def __delitem__(self, __i: SupportsIndex | slice) -> None: ...
+    @overload
+    def __getitem__(self, __i: SupportsIndex) -> _T: ...
+    @overload
+    def __getitem__(self, __s: slice) -> list[_T]: ...
+    @overload
+    def __setitem__(self, __i: SupportsIndex, __o: _T) -> None: ...
+    @overload
+    def __setitem__(self, __s: slice, __o: Iterable[_T]) -> None: ...
+    def __mul__(self, __n: SupportsIndex) -> list[_T]: ...
+    def __rmul__(self, __n: SupportsIndex) -> list[_T]: ...
+    def __reversed__(self) -> Iterator[_T]: ...
+    def append(self, __object: _T) -> None: ...
+    def extend(self, __iterable: Iterable[_T]) -> None: ...
+    def pop(self, __index: SupportsIndex = ...) -> _T: ...
+    def index(self, __value: _T, __start: SupportsIndex = ..., __stop: SupportsIndex = ...) -> int: ...
+    def count(self, __value: _T) -> int: ...
+    def insert(self, __index: SupportsIndex, __object: _T) -> None: ...
+    def remove(self, __value: _T) -> None: ...
+    # Use BaseListProxy[SupportsRichComparisonT] for the first overload rather than [SupportsRichComparison]
+    # to work around invariance
+    @overload
+    def sort(self: BaseListProxy[SupportsRichComparisonT], *, key: None = ..., reverse: bool = ...) -> None: ...
+    @overload
+    def sort(self, *, key: Callable[[_T], SupportsRichComparison], reverse: bool = ...) -> None: ...
+
+class ListProxy(BaseListProxy[_T]):
+    def __iadd__(self: Self, __x: Iterable[_T]) -> Self: ...  # type: ignore[override]
+    def __imul__(self: Self, __n: SupportsIndex) -> Self: ...  # type: ignore[override]
+
 # Returned by BaseManager.get_server()
 class Server:
     address: Any
@@ -124,8 +179,21 @@ class SyncManager(BaseManager):
     def Semaphore(self, value: Any = ...) -> threading.Semaphore: ...
     def Array(self, typecode: Any, sequence: Sequence[_T]) -> Sequence[_T]: ...
     def Value(self, typecode: Any, value: _T) -> ValueProxy[_T]: ...
-    def dict(self, sequence: Mapping[_KT, _VT] = ...) -> _dict[_KT, _VT]: ...
-    def list(self, sequence: Sequence[_T] = ...) -> _list[_T]: ...
+    # Overloads are copied from builtins.dict.__init__
+    @overload
+    def dict(self) -> DictProxy[Any, Any]: ...
+    @overload
+    def dict(self, **kwargs: _VT) -> DictProxy[str, _VT]: ...
+    @overload
+    def dict(self, __map: SupportsKeysAndGetItem[_KT, _VT], **kwargs: _VT) -> DictProxy[_KT, _VT]: ...
+    @overload
+    def dict(self, __iterable: Iterable[tuple[_KT, _VT]], **kwargs: _VT) -> DictProxy[_KT, _VT]: ...
+    @overload
+    def dict(self, __iterable: Iterable[list[str]]) -> DictProxy[str, str]: ...
+    @overload
+    def list(self, __sequence: Sequence[_T]) -> ListProxy[_T]: ...
+    @overload
+    def list(self) -> ListProxy[Any]: ...
 
 class RemoteError(Exception): ...
 

tests/stubtest_allowlists/py3_common.txt

@@ -384,6 +384,22 @@ builtins.super.__self__
 builtins.super.__self_class__
 builtins.super.__thisclass__
 
+# These multiprocessing proxy methods have *args, **kwargs signatures at runtime,
+# But have more precise (accurate) signatures in the stub
+multiprocessing.managers.BaseListProxy.__imul__
+multiprocessing.managers.BaseListProxy.__len__
+multiprocessing.managers.BaseListProxy.__reversed__
+multiprocessing.managers.BaseListProxy.reverse
+multiprocessing.managers.BaseListProxy.sort
+multiprocessing.managers.DictProxy.__iter__
+multiprocessing.managers.DictProxy.__len__
+multiprocessing.managers.DictProxy.clear
+multiprocessing.managers.DictProxy.copy
+multiprocessing.managers.DictProxy.items
+multiprocessing.managers.DictProxy.keys
+multiprocessing.managers.DictProxy.popitem
+multiprocessing.managers.DictProxy.values
+
 # GetSetDescriptor that always raises AttributeError
 builtins.OSError.characters_written
 # Aliases for OSError