gh-146553: Use inspect.unwrap() for cycle detection instead of custom helper

Author: raminfp

Lib/test/test_typing.py

@@ -6842,7 +6842,7 @@ def test_get_type_hints_wrapped_cycle_self(self):
         # not loop forever.
         def f(x: int) -> str: ...
         f.__wrapped__ = f
-        with self.assertRaises(ValueError):
+        with self.assertRaisesRegex(ValueError, 'wrapper loop'):
             get_type_hints(f)
 
     def test_get_type_hints_wrapped_cycle_mutual(self):
@@ -6852,19 +6852,9 @@ def a(): ...
         def b(): ...
         a.__wrapped__ = b
         b.__wrapped__ = a
-        with self.assertRaises(ValueError):
+        with self.assertRaisesRegex(ValueError, 'wrapper loop'):
             get_type_hints(a)
 
-    def test_get_type_hints_wrapped_chain_no_cycle(self):
-        # gh-146553: a valid (non-cyclic) __wrapped__ chain must still work.
-        def inner(x: int) -> str: ...
-        def middle(x: int) -> str: ...
-        middle.__wrapped__ = inner
-        def outer(x: int) -> str: ...
-        outer.__wrapped__ = middle
-        # No cycle — should return the annotations without raising.
-        self.assertEqual(get_type_hints(outer), {'x': int, 'return': str})
-
     def test_get_type_hints_annotated(self):
         def foobar(x: List['X']): ...
         X = Annotated[int, (1, 10)]

Lib/typing.py

@@ -1972,6 +1972,7 @@ def _lazy_load_getattr_static():
 
 _cleanups.append(_lazy_load_getattr_static.cache_clear)
 
+
 def _pickle_psargs(psargs):
     return ParamSpecArgs, (psargs.__origin__,)
 
@@ -2483,20 +2484,9 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False,
         if isinstance(obj, types.ModuleType):
             globalns = obj.__dict__
         else:
-            nsobj = obj
             # Find globalns for the unwrapped object.
-            # Use an id-based visited set to detect and break on cycles in the
-            # __wrapped__ chain (e.g. f.__wrapped__ = f), matching the behavior
-            # of inspect.unwrap().
-            _seen_ids = {id(nsobj)}
-            while hasattr(nsobj, '__wrapped__'):
-                nsobj = nsobj.__wrapped__
-                _nsobj_id = id(nsobj)
-                if _nsobj_id in _seen_ids:
-                    raise ValueError(
-                        f'wrapper loop when unwrapping {obj!r}'
-                    )
-                _seen_ids.add(_nsobj_id)
+            import inspect
+            nsobj = inspect.unwrap(obj)
             globalns = getattr(nsobj, '__globals__', {})
         if localns is None:
             localns = globalns