Mark stub-only private symbols as @type_check_only in third-party stubs (#14545)

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

@@ -1,5 +1,5 @@
 from collections.abc import Callable, Iterable, Iterator, MutableMapping, Sequence
-from typing import Any, Protocol, SupportsIndex, TypeVar, overload
+from typing import Any, Protocol, SupportsIndex, TypeVar, overload, type_check_only
 from typing_extensions import Self
 
 from google.protobuf.descriptor import Descriptor
@@ -12,6 +12,7 @@ _K = TypeVar("_K", bound=bool | int | str)
 _ScalarV = TypeVar("_ScalarV", bound=bool | int | float | str | bytes)
 _MessageV = TypeVar("_MessageV", bound=Message)
 
+@type_check_only
 class _ValueChecker(Protocol[_T]):
     def CheckValue(self, proposed_value: _T) -> _T: ...
     def DefaultValue(self) -> _T: ...

stubs/protobuf/google/protobuf/internal/enum_type_wrapper.pyi

@@ -1,4 +1,4 @@
-from typing import Generic, TypeVar
+from typing import Generic, TypeVar, type_check_only
 
 from google.protobuf.descriptor import EnumDescriptor
 
@@ -9,6 +9,7 @@ _V = TypeVar("_V", bound=int)
 # NOTE: this doesn't actually inherit from type,
 # but mypy doesn't support metaclasses that don't inherit from type,
 # so we pretend it does in the stubs...
+@type_check_only
 class _EnumTypeWrapper(type, Generic[_V]):
     DESCRIPTOR: EnumDescriptor
     def __init__(self, enum_type: EnumDescriptor) -> None: ...

stubs/protobuf/google/protobuf/internal/extension_dict.pyi

@@ -1,5 +1,5 @@
 from collections.abc import Iterator
-from typing import Any, Generic, TypeVar
+from typing import Any, Generic, TypeVar, type_check_only
 
 from google.protobuf.descriptor import FieldDescriptor
 from google.protobuf.internal.containers import RepeatedCompositeFieldContainer, RepeatedScalarFieldContainer
@@ -11,6 +11,7 @@ _ExtenderMessageT = TypeVar(
     bound=Message | RepeatedScalarFieldContainer[Any] | RepeatedCompositeFieldContainer[Any] | bool | float | str | bytes,
 )
 
+@type_check_only
 class _ExtensionFieldDescriptor(FieldDescriptor, Generic[_ContainerMessageT, _ExtenderMessageT]): ...
 
 class _ExtensionDict(Generic[_ContainerMessageT]):

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

@@ -59,15 +59,6 @@ class FieldMask:
         self, source: tAny, destination: tAny, replace_message_field: bool = False, replace_repeated_field: bool = False
     ) -> None: ...
 
-class _FieldMaskTree:
-    def __init__(self, field_mask: Incomplete | None = ...) -> None: ...
-    def MergeFromFieldMask(self, field_mask: tAny) -> None: ...
-    def AddPath(self, path: tAny): ...
-    def ToFieldMask(self, field_mask: tAny) -> None: ...
-    def IntersectPath(self, path: tAny, intersection: tAny): ...
-    def AddLeafNodes(self, prefix: tAny, node: tAny) -> None: ...
-    def MergeMessage(self, source: tAny, destination: tAny, replace_message: tAny, replace_repeated: tAny) -> None: ...
-
 _StructValue: TypeAlias = struct_pb2.Struct | struct_pb2.ListValue | str | float | bool | None
 _StructValueArg: TypeAlias = _StructValue | Mapping[str, _StructValueArg] | Sequence[_StructValueArg]