[3.12] gh-112618: Make Annotated cache typed (#112619) (#112628)

Lib/test/test_typing.py

@@ -8403,6 +8403,40 @@ class AnnotatedTests(BaseTestCase):
         self.assertEqual(X.__mro__, (X, int, object),
                          "Annotated should be transparent.")
 
+    def test_annotated_cached_with_types(self):
+        class A(str): ...
+        class B(str): ...
+
+        field_a1 = Annotated[str, A("X")]
+        field_a2 = Annotated[str, B("X")]
+        a1_metadata = field_a1.__metadata__[0]
+        a2_metadata = field_a2.__metadata__[0]
+
+        self.assertIs(type(a1_metadata), A)
+        self.assertEqual(a1_metadata, A("X"))
+        self.assertIs(type(a2_metadata), B)
+        self.assertEqual(a2_metadata, B("X"))
+        self.assertIsNot(type(a1_metadata), type(a2_metadata))
+
+        field_b1 = Annotated[str, A("Y")]
+        field_b2 = Annotated[str, B("Y")]
+        b1_metadata = field_b1.__metadata__[0]
+        b2_metadata = field_b2.__metadata__[0]
+
+        self.assertIs(type(b1_metadata), A)
+        self.assertEqual(b1_metadata, A("Y"))
+        self.assertIs(type(b2_metadata), B)
+        self.assertEqual(b2_metadata, B("Y"))
+        self.assertIsNot(type(b1_metadata), type(b2_metadata))
+
+        field_c1 = Annotated[int, 1]
+        field_c2 = Annotated[int, 1.0]
+        field_c3 = Annotated[int, True]
+
+        self.assertIs(type(field_c1.__metadata__[0]), int)
+        self.assertIs(type(field_c2.__metadata__[0]), float)
+        self.assertIs(type(field_c3.__metadata__[0]), bool)
+
 
 class TypeAliasTests(BaseTestCase):
     def test_canonical_usage_with_variable_annotation(self):

Lib/typing.py

@@ -2065,9 +2065,14 @@ class Annotated:
     def __new__(cls, *args, **kwargs):
         raise TypeError("Type Annotated cannot be instantiated.")
 
-    @_tp_cache
     def __class_getitem__(cls, params):
-        if not isinstance(params, tuple) or len(params) < 2:
+        if not isinstance(params, tuple):
+            params = (params,)
+        return cls._class_getitem_inner(cls, *params)
+
+    @_tp_cache(typed=True)
+    def _class_getitem_inner(cls, *params):
+        if len(params) < 2:
             raise TypeError("Annotated[...] should be used "
                             "with at least two arguments (a type and an "
                             "annotation).")

Misc/NEWS.d/next/Library/2023-12-02-12-55-17.gh-issue-112618.7_FT8-.rst

@@ -0,0 +1,2 @@
+Fix a caching bug relating to :data:`typing.Annotated`.
+``Annotated[str, True]`` is no longer identical to ``Annotated[str, 1]``.