bpo-37953: Fix ForwardRef hash and equality checks (GH-15400) (GH-18751)

Ideally if we stick a ForwardRef in a dictionary we would like to reliably be able to get it out again.

https://bugs.python.org/issue37953
(cherry picked from commit e082e7c)

Co-authored-by: plokmijnuhby <39633434+plokmijnuhby@users.noreply.github.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/Lib/typing.py b/Lib/typing.py
index 3b2e372..1749c2f 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -473,11 +473,13 @@ class ForwardRef(_Final, _root=True):
     def __eq__(self, other):
         if not isinstance(other, ForwardRef):
             return NotImplemented
-        return (self.__forward_arg__ == other.__forward_arg__ and
-                self.__forward_value__ == other.__forward_value__)
+        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__
 
     def __hash__(self):
-        return hash((self.__forward_arg__, self.__forward_value__))
+        return hash(self.__forward_arg__)
 
     def __repr__(self):
         return f'ForwardRef({self.__forward_arg__!r})'