Escape double stringified annotations on typing.ForwardRef

python · gvanrossum · Oct 6, 2020 · May 27, 2020 · May 27, 2020 · May 27, 2020
commit bbf01bba8d6992cff42d20a4de273b4acbeebb7e
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
@@ -635,7 +635,7 @@ def test_default_update(self):
         self.assertEqual(wrapper.__name__, 'f')
         self.assertEqual(wrapper.__qualname__, f.__qualname__)
         self.assertEqual(wrapper.attr, 'This is also a test')
-        self.assertEqual(wrapper.__annotations__['a'], 'This is a new annotation')
+        self.assertEqual(wrapper.__annotations__['a'], repr('This is a new annotation'))
         self.assertNotIn('b', wrapper.__annotations__)
 
     @unittest.skipIf(sys.flags.optimize >= 2,

diff --git a/Lib/typing.py b/Lib/typing.py
@@ -469,6 +469,11 @@ class ForwardRef(_Final, _root=True):
     def __init__(self, arg, is_argument=True):
         if not isinstance(arg, str):
             raise TypeError(f"Forward reference must be a string -- got {arg!r}")
+        # since annotations feature is now default, stringified annotations
+        # should be escaped from quotes, or this will result with double
+        # forward refs.
+        if arg[0] in "'\"" and arg[-1] in "'\"":
+            arg = arg[1:-1]
         try:
             code = compile(arg, '<string>', 'eval')
         except SyntaxError: