Add _GeneratorContextManagerBase to contextlib

Author: AlexWaygood

stdlib/contextlib.pyi

@@ -8,6 +8,7 @@ from typing import (
     Awaitable,
     Callable,
     ContextManager,
+    Generator,
     Generic,
     Iterator,
     Optional,
@@ -26,6 +27,8 @@ if sys.version_info >= (3, 7):
 
 _T = TypeVar("_T")
 _T_co = TypeVar("_T_co", covariant=True)
+_T_contra = TypeVar("_T_contra", contravariant=True)
+_V_co = TypeVar("_V_co", covariant=True)
 _T_io = TypeVar("_T_io", bound=Optional[IO[str]])
 _F = TypeVar("_F", bound=Callable[..., Any])
 _P = ParamSpec("_P")
@@ -36,7 +39,22 @@ _CM_EF = TypeVar("_CM_EF", AbstractContextManager[Any], _ExitFunc)
 class ContextDecorator:
     def __call__(self, func: _F) -> _F: ...
 
-class _GeneratorContextManager(AbstractContextManager[_T_co], ContextDecorator): ...
+if sys.version_info >= (3, 7):
+    class _GeneratorContextManagerBase(Generic[_P, _T_co, _T_contra, _V_co]):  # type: ignore[misc]
+        def __init__(self, func: Callable[_P, Generator[_T_co, _T_contra, _V_co]], args: _P.args, **kwds: _P.kwargs) -> None: ...
+        gen: Generator[_T_co, _T_contra, _V_co]
+        func: Callable[_P, Generator[_T_co, _T_contra, _V_co]]  # type: ignore[misc]
+        args: _P.args
+        kwds: _P.kwargs
+    class _GeneratorContextManager(  # type: ignore[misc]
+        _GeneratorContextManagerBase[_P, _T_co, _T_contra, _V_co],  # type: ignore[misc]
+        AbstractContextManager[_T_co],
+        ContextDecorator,
+        Generic[_P, _T_co, _T_contra, _V_co],  # type: ignore[misc]
+    ): ...
+
+else:
+    class _GeneratorContextManager(AbstractContextManager[_T_co], ContextDecorator): ...
 
 # type ignore to deal with incomplete ParamSpec support in mypy
 def contextmanager(func: Callable[_P, Iterator[_T]]) -> Callable[_P, _GeneratorContextManager[_T]]: ...  # type: ignore[misc]
@@ -45,7 +63,12 @@ if sys.version_info >= (3, 10):
     _AF = TypeVar("_AF", bound=Callable[..., Awaitable[Any]])
     class AsyncContextDecorator:
         def __call__(self, func: _AF) -> _AF: ...
-    class _AsyncGeneratorContextManager(AbstractAsyncContextManager[_T_co], AsyncContextDecorator): ...
+    class _AsyncGeneratorContextManager(
+        _GeneratorContextManagerBase[_P, _T_co, _T_contra, _V_co],
+        AbstractAsyncContextManager[_T_co],
+        AsyncContextDecorator,
+        Generic[_P, _T_co, _T_contra, _V_co],
+    ): ...
 
 elif sys.version_info >= (3, 7):
     class _AsyncGeneratorContextManager(AbstractAsyncContextManager[_T_co]): ...