Fix recursion error for inference of self-referencing class attribute (#1392)

Author: DanielNoord

ChangeLog

@@ -43,6 +43,11 @@ Release date: TBA
   Closes #1282
   Ref #1103
 
+* Fixed crash with recursion error for inference of class attributes that referenced
+  the class itself.
+
+  Closes PyCQA/pylint#5408
+
 * Fixed crash when trying to infer ``items()`` on the ``__dict__``
   attribute of an imported module.
 

astroid/inference_tip.py

@@ -7,12 +7,18 @@
 
 import wrapt
 
-from astroid.exceptions import InferenceOverwriteError
+from astroid import bases, util
+from astroid.exceptions import InferenceOverwriteError, UseInferenceDefault
 from astroid.nodes import NodeNG
 
 InferFn = typing.Callable[..., typing.Any]
+InferOptions = typing.Union[
+    NodeNG, bases.Instance, bases.UnboundMethod, typing.Type[util.Uninferable]
+]
 
-_cache: typing.Dict[typing.Tuple[InferFn, NodeNG], typing.Any] = {}
+_cache: typing.Dict[
+    typing.Tuple[InferFn, NodeNG], typing.Optional[typing.List[InferOptions]]
+] = {}
 
 
 def clear_inference_tip_cache():
@@ -21,13 +27,21 @@ def clear_inference_tip_cache():
 
 
 @wrapt.decorator
-def _inference_tip_cached(func, instance, args, kwargs):
+def _inference_tip_cached(
+    func: InferFn, instance: None, args: typing.Any, kwargs: typing.Any
+) -> typing.Iterator[InferOptions]:
     """Cache decorator used for inference tips"""
     node = args[0]
     try:
         result = _cache[func, node]
+        # If through recursion we end up trying to infer the same
+        # func + node we raise here.
+        if result is None:
+            raise UseInferenceDefault()
     except KeyError:
+        _cache[func, node] = None
         result = _cache[func, node] = list(func(*args, **kwargs))
+        assert result
     return iter(result)
 
 

tests/unittest_inference.py

@@ -6621,5 +6621,43 @@ def test_inference_of_items_on_module_dict() -> None:
     builder.file_build(str(DATA_DIR / "module_dict_items_call" / "test.py"), "models")
 
 
+def test_recursion_on_inference_tip() -> None:
+    """Regression test for recursion in inference tip.
+
+    Originally reported in https://github.com/PyCQA/pylint/issues/5408.
+    """
+    code = """
+    class MyInnerClass:
+        ...
+
+
+    class MySubClass:
+        inner_class = MyInnerClass
+
+
+    class MyClass:
+        sub_class = MySubClass()
+
+
+    def get_unpatched_class(cls):
+        return cls
+
+
+    def get_unpatched(item):
+        lookup = get_unpatched_class if isinstance(item, type) else lambda item: None
+        return lookup(item)
+
+
+    _Child = get_unpatched(MyClass.sub_class.inner_class)
+
+
+    class Child(_Child):
+        def patch(cls):
+            MyClass.sub_class.inner_class = cls
+    """
+    module = parse(code)
+    assert module
+
+
 if __name__ == "__main__":
     unittest.main()