gh-112618: Make `Annotated` cache typed (#112619)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/Lib/typing.py b/Lib/typing.py
index b3af701..4c19aad 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -490,7 +490,7 @@ class _SpecialForm(_Final, _NotIterable, _root=True):
         return self._getitem(self, parameters)
 
 
-class _LiteralSpecialForm(_SpecialForm, _root=True):
+class _TypedCacheSpecialForm(_SpecialForm, _root=True):
     def __getitem__(self, parameters):
         if not isinstance(parameters, tuple):
             parameters = (parameters,)
@@ -723,7 +723,7 @@ def Optional(self, parameters):
     arg = _type_check(parameters, f"{self} requires a single type.")
     return Union[arg, type(None)]
 
-@_LiteralSpecialForm
+@_TypedCacheSpecialForm
 @_tp_cache(typed=True)
 def Literal(self, *parameters):
     """Special typing form to define literal types (a.k.a. value types).
@@ -2005,8 +2005,9 @@ class _AnnotatedAlias(_NotIterable, _GenericAlias, _root=True):
         return (self.__origin__,)
 
 
-@_SpecialForm
-def Annotated(self, params):
+@_TypedCacheSpecialForm
+@_tp_cache(typed=True)
+def Annotated(self, *params):
     """Add context-specific metadata to a type.
 
     Example: Annotated[int, runtime_check.Unsigned] indicates to the
@@ -2053,7 +2054,7 @@ def Annotated(self, params):
       where T1, T2 etc. are TypeVars, which would be invalid, because
       only one type should be passed to Annotated.
     """
-    if not isinstance(params, tuple) or len(params) < 2:
+    if len(params) < 2:
         raise TypeError("Annotated[...] should be used "
                         "with at least two arguments (a type and an "
                         "annotation).")