[3.10] bpo-46333: Honor module parameter in ForwardRef (GH-30536) (GH-31379)

The `module` parameter carries semantic information about the forward ref.
Forward refs are different if they refer to different module even if they
have the same name. This affects the `__eq__`, `__repr__` and `__hash__` methods.

Co-authored-by: Andreas Hangauer <[email protected]>
Co-authored-by: Alex Waygood <[email protected]>
Co-authored-by: Ken Jin <[email protected]>
(cherry picked from commit 6e7b813)


Co-authored-by: aha79 <[email protected]>

Automerge-Triggered-By: GH:JelleZijlstra

Author: miss-islington

Lib/test/test_typing.py

@@ -2658,6 +2658,10 @@ def test_forward_equality(self):
         fr = typing.ForwardRef('int')
         self.assertEqual(fr, typing.ForwardRef('int'))
         self.assertNotEqual(List['int'], List[int])
+        self.assertNotEqual(fr, typing.ForwardRef('int', module=__name__))
+        frm = typing.ForwardRef('int', module=__name__)
+        self.assertEqual(frm, typing.ForwardRef('int', module=__name__))
+        self.assertNotEqual(frm, typing.ForwardRef('int', module='__other_name__'))
 
     def test_forward_equality_gth(self):
         c1 = typing.ForwardRef('C')
@@ -2694,6 +2698,14 @@ def foo(a: c1_gth, b: c2_gth):
         self.assertEqual(hash(c1_gth), hash(c2_gth))
         self.assertEqual(hash(c1), hash(c1_gth))
 
+        c3 = typing.ForwardRef('int', module=__name__)
+        c4 = typing.ForwardRef('int', module='__other_name__')
+
+        self.assertNotEqual(hash(c3), hash(c1))
+        self.assertNotEqual(hash(c3), hash(c1_gth))
+        self.assertNotEqual(hash(c3), hash(c4))
+        self.assertEqual(hash(c3), hash(typing.ForwardRef('int', module=__name__)))
+
     def test_forward_equality_namespace(self):
         class A:
             pass

Lib/typing.py

@@ -705,10 +705,11 @@ def __eq__(self, other):
         if self.__forward_evaluated__ and other.__forward_evaluated__:
             return (self.__forward_arg__ == other.__forward_arg__ and
                     self.__forward_value__ == other.__forward_value__)
-        return self.__forward_arg__ == other.__forward_arg__
+        return (self.__forward_arg__ == other.__forward_arg__ and
+                self.__forward_module__ == other.__forward_module__)
 
     def __hash__(self):
-        return hash(self.__forward_arg__)
+        return hash((self.__forward_arg__, self.__forward_module__))
 
     def __repr__(self):
         return f'ForwardRef({self.__forward_arg__!r})'

Misc/ACKS

@@ -677,6 +677,7 @@ Anders Hammarquist
 Mark Hammond
 Harald Hanche-Olsen
 Manus Hand
+Andreas Hangauer
 Milton L. Hankins
 Carl Bordum Hansen
 Stephen Hansen

Misc/NEWS.d/next/Library/2022-01-11-15-54-15.bpo-46333.B1faiF.rst

@@ -0,0 +1,4 @@
+The :meth:`__eq__` and :meth:`__hash__` methods of
+:class:`typing.ForwardRef` now honor the ``module`` parameter of
+:class:`typing.ForwardRef`. Forward references from different
+modules are now differentiated.