gh-132493: enable protocol isinstance checks against classes with def…

…erred annotations
python · JelleZijlstra · Apr 16, 2025 · Apr 14, 2025 · Apr 15, 2025 · Apr 15, 2025
commit 34c60398388ff64e0cc82668df4ed160bdf0f671
@@ -4554,6 +4554,18 @@ class Commentable(Protocol):
        )
        self.assertIs(type(exc.__cause__), CustomError)

+    def test_isinstance_with_deffered_evaluation_of_annotations(self):
+        @runtime_checkable
+        class P(Protocol):
+            x: undefined
+            def meth(self):
+                ...
+
+        class DeferredClass:
+            x: undefined
+
+        self.assertFalse(isinstance(DeferredClass(), P))
+

 class GenericTests(BaseTestCase):


@@ -1801,7 +1801,7 @@ def _get_protocol_attrs(cls):
    for base in cls.__mro__[:-1]:  # without object
        if base.__name__ in {'Protocol', 'Generic'}:
            continue
-        annotations = getattr(base, '__annotations__', {})
+        annotations = _lazy_annotationlib.get_annotations(base, format=_lazy_annotationlib.Format.FORWARDREF)
        for attr in (*base.__dict__, *annotations):
            if not attr.startswith('_abc_') and attr not in EXCLUDED_ATTRIBUTES:
                attrs.add(attr)
@@ -2018,7 +2018,7 @@ def _proto_hook(cls, other):
                break

            # ...or in annotations, if it is a sub-protocol.
-            annotations = getattr(base, '__annotations__', {})
+            annotations = _lazy_annotationlib.get_annotations(base, format=_lazy_annotationlib.Format.FORWARDREF)
            if (isinstance(annotations, collections.abc.Mapping) and
                    attr in annotations and
                    issubclass(other, Generic) and getattr(other, '_is_protocol', False)):
-Original file line number
+Diff line change
@@ -4554,6 +4554,18 @@ class Commentable(Protocol):
             )
             self.assertIs(type(exc.__cause__), CustomError)
+        def test_isinstance_with_deffered_evaluation_of_annotations(self):
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+            @runtime_checkable
+            class P(Protocol):
+                x: undefined
+                def meth(self):
+                    ...
+            class DeferredClass:
+                x: undefined
+            self.assertFalse(isinstance(DeferredClass(), P))
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            JelleZijlstra
  

      

      

      


        Apr 14, 2025


      
    

  


        
      
  
  
  
    

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      Also add a test with a class that does fulfill the protocol.
Also, please add a NEWS entry.
    
  
  


    

        
      
  
  
    
  
  
  
    
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            felixscherz
  

      

      

      


        Apr 15, 2025


      
    

  


        
      
  
  
  
    

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      I added a class that satisfies the protocol and a NEWS entry:)
    
  
  


    

        
      
  
  
    
  
  
  
    
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     class GenericTests(BaseTestCase):
-          Expand Down