Prevent a recursion error for self reference variables and type() calls.

The recursion error was caused by inferring the bases of the generated
`B` class multiple times. The solution uses the new `EvaluatedObject`
class to stop the inference by inferring the base classes in the
`type` inference function.

Close #199

Author: PCManticore

ChangeLog

@@ -18,6 +18,10 @@ Release Date: TBA
 
   Close PyCQA/pylint#2991
 
+* Prevent a recursion error for self reference variables and `type()` calls.
+
+  Close #199
+
 * Do not infer the first argument of a staticmethod in a metaclass as the class itself
 
   Close PyCQA/pylint#3032

astroid/scoped_nodes.py

@@ -2126,7 +2126,14 @@ def _infer_type_call(self, caller, context):
         # Get the bases of the class.
         class_bases = next(caller.args[1].infer(context))
         if isinstance(class_bases, (node_classes.Tuple, node_classes.List)):
-            result.bases = class_bases.itered()
+            bases = []
+            for base in class_bases.itered():
+                inferred = next(base.infer(context=context))
+                if inferred:
+                    bases.append(
+                        node_classes.EvaluatedObject(original=base, value=inferred)
+                    )
+            result.bases = bases
         else:
             # There is currently no AST node that can represent an 'unknown'
             # node (Uninferable is not an AST node), therefore we simply return Uninferable here

tests/unittest_inference.py

@@ -5779,5 +5779,25 @@ def test_recursion_error_metaclass_monkeypatching():
     assert cls.declared_metaclass() is None
 
 
+@pytest.mark.xfail(reason="Cannot fully infer all the base classes properly.")
+def test_recursion_error_self_reference_type_call():
+    # Fix for https://github.com/PyCQA/astroid/issues/199
+    code = """
+    class A(object):
+        pass
+    class SomeClass(object):
+        route_class = A
+        def __init__(self):
+            self.route_class = type('B', (self.route_class, ), {})
+            self.route_class() #@
+    """
+    node = extract_node(code)
+    inferred = next(node.infer())
+    assert isinstance(inferred, Instance)
+    assert inferred.name == "B"
+    # TODO: Cannot infer [B, A, object] but at least the recursion error is gone.
+    assert [cls.name for cls in inferred.mro()] == ["B", "A", "object"]
+
+
 if __name__ == "__main__":
     unittest.main()