Add __slots__ to third-party packages using stubdefaulter (#14619)

stubs/protobuf/@tests/stubtest_allowlist.txt

@@ -31,3 +31,7 @@ google.protobuf.descriptor.OneofDescriptor
 
 # Runtime does not have __iter__ (yet...): hack in spirit of https://github.com/python/typeshed/issues/7813
 google.protobuf.internal.well_known_types.ListValue.__iter__
+
+# It's a list at runtime, but if we do that pyright complains about incompatible overrides
+# in subclasses that use a tuple for __slots__.
+google.protobuf.message.Message.__slots__

stubs/protobuf/google/protobuf/internal/containers.pyi

@@ -18,6 +18,7 @@ class _ValueChecker(Protocol[_T]):
     def DefaultValue(self) -> _T: ...
 
 class BaseContainer(Sequence[_T]):
+    __slots__ = ["_message_listener", "_values"]
     def __init__(self, message_listener: MessageListener) -> None: ...
     def __len__(self) -> int: ...
     def __ne__(self, other: object) -> bool: ...
@@ -30,6 +31,7 @@ class BaseContainer(Sequence[_T]):
     def __getitem__(self, key: slice) -> list[_T]: ...
 
 class RepeatedScalarFieldContainer(BaseContainer[_ScalarV]):
+    __slots__ = ["_type_checker"]
     def __init__(self, message_listener: MessageListener, type_checker: _ValueChecker[_ScalarV]) -> None: ...
     def append(self, value: _ScalarV) -> None: ...
     def insert(self, key: int, value: _ScalarV) -> None: ...
@@ -45,6 +47,7 @@ class RepeatedScalarFieldContainer(BaseContainer[_ScalarV]):
     def __eq__(self, other: object) -> bool: ...
 
 class RepeatedCompositeFieldContainer(BaseContainer[_MessageV]):
+    __slots__ = ["_message_descriptor"]
     def __init__(self, message_listener: MessageListener, message_descriptor: Descriptor) -> None: ...
     def add(self, **kwargs: Any) -> _MessageV: ...
     def append(self, value: _MessageV) -> None: ...
@@ -57,6 +60,7 @@ class RepeatedCompositeFieldContainer(BaseContainer[_MessageV]):
     def __eq__(self, other: object) -> bool: ...
 
 class ScalarMap(MutableMapping[_K, _ScalarV]):
+    __slots__ = ["_key_checker", "_value_checker", "_values", "_message_listener", "_entry_descriptor"]
     def __init__(
         self,
         message_listener: MessageListener,
@@ -82,6 +86,7 @@ class ScalarMap(MutableMapping[_K, _ScalarV]):
     def GetEntryClass(self) -> GeneratedProtocolMessageType: ...
 
 class MessageMap(MutableMapping[_K, _MessageV]):
+    __slots__ = ["_key_checker", "_values", "_message_listener", "_message_descriptor", "_entry_descriptor"]
     def __init__(
         self,
         message_listener: MessageListener,

stubs/protobuf/google/protobuf/internal/well_known_types.pyi

@@ -7,6 +7,7 @@ from typing_extensions import TypeAlias
 from google.protobuf import struct_pb2
 
 class Any:
+    __slots__ = ()
     type_url: str
     value: Incomplete
     def Pack(self, msg, type_url_prefix: str = "type.googleapis.com/", deterministic=None) -> None: ...
@@ -15,6 +16,7 @@ class Any:
     def Is(self, descriptor) -> bool: ...
 
 class Timestamp:
+    __slots__ = ()
     def ToJsonString(self) -> str: ...
     seconds: int
     nanos: int
@@ -32,6 +34,7 @@ class Timestamp:
     def FromDatetime(self, dt: datetime) -> None: ...
 
 class Duration:
+    __slots__ = ()
     def ToJsonString(self) -> str: ...
     seconds: int
     nanos: int
@@ -48,6 +51,7 @@ class Duration:
     def FromTimedelta(self, td: timedelta) -> None: ...
 
 class FieldMask:
+    __slots__ = ()
     def ToJsonString(self) -> str: ...
     def FromJsonString(self, value: tAny) -> None: ...
     def IsValidForDescriptor(self, message_descriptor: tAny): ...
@@ -63,6 +67,7 @@ _StructValue: TypeAlias = struct_pb2.Struct | struct_pb2.ListValue | str | float
 _StructValueArg: TypeAlias = _StructValue | Mapping[str, _StructValueArg] | Sequence[_StructValueArg]
 
 class Struct:
+    __slots__: tuple[()] = ()
     def __getitem__(self, key: str) -> _StructValue: ...
     def __setitem__(self, key: str, value: _StructValueArg) -> None: ...
     def __delitem__(self, key: str) -> None: ...
@@ -76,6 +81,7 @@ class Struct:
     def update(self, dictionary: SupportsItems[str, _StructValueArg]) -> None: ...
 
 class ListValue:
+    __slots__: tuple[()] = ()
     def __len__(self) -> int: ...
     def append(self, value: _StructValue) -> None: ...
     def extend(self, elem_seq: Iterable[_StructValue]) -> None: ...

stubs/protobuf/google/protobuf/message.pyi

@@ -12,6 +12,7 @@ class DecodeError(Error): ...
 class EncodeError(Error): ...
 
 class Message:
+    __slots__: tuple[()] = ()
     DESCRIPTOR: Descriptor | _upb_Descriptor
     def __deepcopy__(self, memo: Any = None) -> Self: ...
     def __eq__(self, other_msg): ...