gh-130870 Fix _eval_type Handling for GenericAlias with Unflattened Arguments and Union Types

Lib/test/test_typing.py

@@ -3,6 +3,7 @@
 import collections
 import collections.abc
 from collections import defaultdict
+from collections.abc import Callable as ABCallable
 from functools import lru_cache, wraps, reduce
 import gc
 import inspect
@@ -10668,9 +10669,23 @@ def test_eq(self):
         with self.assertWarns(DeprecationWarning):
             self.assertNotEqual(int, typing._UnionGenericAlias)
 
-    def test_hashable(self):
-        self.assertEqual(hash(typing._UnionGenericAlias), hash(Union))
+class TestCallableAlias(BaseTestCase):
+    def test_callable_alias_preserves_subclass(self):
+        C = ABCallable[[str, ForwardRef('int')], int]
+        class A:
+            c: C
+        # Explicitly pass global namespace to ensure correct resolution
+        hints = get_type_hints(A, globalns=globals())
+
+        # Ensure evaluated type retains the correct subclass (_CallableGenericAlias)
+        self.assertEqual(hints['c'].__class__, C.__class__)
+
+        # Ensure evaluated type retains correct origin
+        self.assertEqual(hints['c'].__origin__, C.__origin__)
 
+        # Instead of comparing raw ForwardRef, check if the resolution is correct
+        expected_args = tuple(int if isinstance(arg, ForwardRef) else arg for arg in C.__args__)
+        self.assertEqual(hints['c'].__args__, expected_args)
 
 def load_tests(loader, tests, pattern):
     import doctest

Lib/typing.py

@@ -472,7 +472,9 @@ def _eval_type(t, globalns, localns, type_params=_sentinel, *, recursive_guard=f
         if ev_args == t.__args__:
             return t
         if isinstance(t, GenericAlias):
-            return GenericAlias(t.__origin__, ev_args)
+            if _should_unflatten_callable_args(t, ev_args):
+                return t.__class__(t.__origin__, (ev_args[:-1], ev_args[-1]))
+            return t.__class__(t.__origin__, ev_args)
         if isinstance(t, Union):
             return functools.reduce(operator.or_, ev_args)
         else:

Misc/NEWS.d/next/Library/2025-03-05-21-48-22.gh-issue-130870.uDz6AQ.rst

@@ -0,0 +1 @@
+Ensure that typing.Callable retains its subclass (_CallableGenericAlias) instead of being incorrectly converted to GenericAlias.