Fix <py3.9 Annotated

pydantic/typing.py

@@ -129,12 +129,25 @@ def get_args(tp: Type[Any]) -> Tuple[Any, ...]:
 
 if sys.version_info < (3, 9):
     if TYPE_CHECKING:
-        from typing_extensions import Annotated
+        from typing_extensions import Annotated, _AnnotatedAlias
     else:  # due to different mypy warnings raised during CI for python 3.7 and 3.8
         try:
-            from typing_extensions import Annotated
+            from typing_extensions import Annotated, _AnnotatedAlias
         except ImportError:
-            Annotated = None
+            Annotated, _AnnotatedAlias = None, None
+
+    from typing_extensions import get_origin as typing_extensions_get_origin
+
+    # Our custom get_origin for <3.8 and the builtin 3.8 get_origin don't recognize
+    # typing_extensions.Annotated, so wrap them to short-circuit with typing_extensions.get_origin.
+    # We still want to use our wrapped get_origins defined above for non-Annotated data.
+    _get_origin = get_origin
+
+    def get_origin(tp: Type[Any]) -> Type[Any]:
+        if _AnnotatedAlias is not None and isinstance(tp, _AnnotatedAlias):
+            return typing_extensions_get_origin(tp)
+        return _get_origin(tp)
+
 else:
     from typing import Annotated
 
@@ -157,6 +170,7 @@ def get_args(tp: Type[Any]) -> Tuple[Any, ...]:
 __all__ = (
     'ForwardRef',
     'Callable',
+    'Annotated',
     'AnyCallable',
     'NoArgAnyCallable',
     'NoneType',