Shield compatibility

httpcore/_synchronization.py

@@ -30,10 +30,16 @@
     anyio = None  # type: ignore
 
 
-if sys.version_info >= (3, 11):
-    import asyncio as asyncio_timeout  # pragma: nocover
-else:
-    import async_timeout as asyncio_timeout  # pragma: nocover
+if sys.version_info >= (3, 11):  # pragma: nocover
+    import asyncio as asyncio_timeout
+
+    anyio_shield = None
+else:  # pragma: nocover
+    import async_timeout as asyncio_timeout
+
+    if anyio is None:  # pragma: nocover
+        raise RuntimeError("Running in Python<3.11 requires anyio")
+    anyio_shield = anyio.CancelScope
 
 
 AsyncBackend = Literal["asyncio", "trio"]
@@ -226,6 +232,9 @@ async def shield(shielded: Callable[[], Coroutine[Any, Any, None]]) -> None:
         if current_async_backend() == "trio":
             with trio.CancelScope(shield=True):
                 await shielded()
+        elif sys.version_info < (3, 11):
+            with anyio_shield(shield=True):
+                await shielded()
         else:
             await AsyncShieldCancellation._asyncio_shield(shielded)
 
@@ -236,7 +245,7 @@ async def _asyncio_shield(
         inner_task = asyncio.create_task(shielded())
         try:
             await asyncio.shield(inner_task)
-        except asyncio.CancelledError:
+        except (asyncio.exceptions.CancelledError, asyncio.CancelledError):
             # Let the inner_task to complete as it was shielded from the cancellation
             await inner_task