delete _importlib_modulespec (#5350)

* delete _importlib_modulespec

* use typing_extensions.runtime_checkable

stdlib/importlib/abc.pyi

@@ -2,12 +2,9 @@ import sys
 import types
 from _typeshed import AnyPath
 from abc import ABCMeta, abstractmethod
-from typing import IO, Any, Iterator, Mapping, Optional, Sequence, Tuple, Union
-from typing_extensions import Literal
-
-# Loader is exported from this module, but for circular import reasons
-# exists in its own stub file (with ModuleSpec and ModuleType).
-from _importlib_modulespec import Loader as Loader, ModuleSpec  # Exported
+from importlib.machinery import ModuleSpec
+from typing import IO, Any, Iterator, Mapping, Optional, Protocol, Sequence, Tuple, Union
+from typing_extensions import Literal, runtime_checkable
 
 _Path = Union[bytes, str]
 
@@ -54,6 +51,17 @@ class PathEntryFinder(Finder):
     # Not defined on the actual class, but expected to exist.
     def find_spec(self, fullname: str, target: Optional[types.ModuleType] = ...) -> Optional[ModuleSpec]: ...
 
+class Loader(metaclass=ABCMeta):
+    def load_module(self, fullname: str) -> types.ModuleType: ...
+    def module_repr(self, module: types.ModuleType) -> str: ...
+    def create_module(self, spec: ModuleSpec) -> Optional[types.ModuleType]: ...
+    # Not defined on the actual class for backwards-compatibility reasons,
+    # but expected in new code.
+    def exec_module(self, module: types.ModuleType) -> None: ...
+
+class _LoaderProtocol(Protocol):
+    def load_module(self, fullname: str) -> types.ModuleType: ...
+
 class FileLoader(ResourceLoader, ExecutionLoader, metaclass=ABCMeta):
     name: str
     path: _Path
@@ -74,7 +82,6 @@ if sys.version_info >= (3, 7):
         def contents(self) -> Iterator[str]: ...
 
 if sys.version_info >= (3, 9):
-    from typing import Protocol, runtime_checkable
     @runtime_checkable
     class Traversable(Protocol):
         @abstractmethod

stdlib/importlib/machinery.pyi

@@ -1,10 +1,26 @@
 import importlib.abc
 import types
-from typing import Callable, List, Optional, Sequence, Tuple, Union
+from typing import Any, Callable, List, Optional, Sequence, Tuple, Union
 
-# ModuleSpec is exported from this module, but for circular import
-# reasons exists in its own stub file (with Loader and ModuleType).
-from _importlib_modulespec import Loader, ModuleSpec as ModuleSpec  # Exported
+# TODO: the loaders seem a bit backwards, attribute is protocol but __init__ arg isn't?
+class ModuleSpec:
+    def __init__(
+        self,
+        name: str,
+        loader: Optional[importlib.abc.Loader],
+        *,
+        origin: Optional[str] = ...,
+        loader_state: Any = ...,
+        is_package: Optional[bool] = ...,
+    ) -> None: ...
+    name: str
+    loader: Optional[importlib.abc._LoaderProtocol]
+    origin: Optional[str]
+    submodule_search_locations: Optional[List[str]]
+    loader_state: Any
+    cached: Optional[str]
+    parent: Optional[str]
+    has_location: bool
 
 class BuiltinImporter(importlib.abc.MetaPathFinder, importlib.abc.InspectLoader):
     # MetaPathFinder
@@ -78,7 +94,7 @@ class PathFinder:
         cls, fullname: str, path: Optional[Sequence[Union[bytes, str]]] = ..., target: Optional[types.ModuleType] = ...
     ) -> Optional[ModuleSpec]: ...
     @classmethod
-    def find_module(cls, fullname: str, path: Optional[Sequence[Union[bytes, str]]] = ...) -> Optional[Loader]: ...
+    def find_module(cls, fullname: str, path: Optional[Sequence[Union[bytes, str]]] = ...) -> Optional[importlib.abc.Loader]: ...
 
 SOURCE_SUFFIXES: List[str]
 DEBUG_BYTECODE_SUFFIXES: List[str]