Prevent creating Instance that proxies another Instance when inferring __new__(cls) (#1682)

Author: jacobtylerwalls

ChangeLog

@@ -109,6 +109,11 @@ Release date: TBA
 
   Closes PyCQA/pylint#7092
 
+* Prevent creating ``Instance`` objects that proxy other ``Instance``s when there is
+  ambiguity (or user error) in calling ``__new__(cls)``.
+
+  Refs PyCQA/pylint#7109
+
 
 What's New in astroid 2.11.6?
 =============================

astroid/bases.py

@@ -293,6 +293,9 @@ class Instance(BaseInstance):
     # pylint: disable=unnecessary-lambda
     special_attributes = lazy_descriptor(lambda: objectmodel.InstanceModel())
 
+    def __init__(self, proxied: nodes.ClassDef) -> None:
+        super().__init__(proxied)
+
     def __repr__(self):
         return "<Instance of {}.{} at 0x{}>".format(
             self._proxied.root().name, self._proxied.name, id(self)
@@ -434,9 +437,12 @@ def _infer_builtin_new(
                 return
 
         node_context = context.extra_context.get(caller.args[0])
-        infer = caller.args[0].infer(context=node_context)
-
-        yield from (Instance(x) if x is not Uninferable else x for x in infer)  # type: ignore[misc,arg-type]
+        for inferred in caller.args[0].infer(context=node_context):
+            if inferred is Uninferable:
+                yield inferred
+            if isinstance(inferred, nodes.ClassDef):
+                yield Instance(inferred)
+            raise InferenceError
 
     def bool_value(self, context=None):
         return True

tests/unittest_inference.py

@@ -3799,6 +3799,15 @@ def test_builtin_new() -> None:
         with pytest.raises(InferenceError):
             next(ast_node4.infer())
 
+        ast_node5 = extract_node(
+            """
+        class A:  pass
+        A.__new__(A())  #@
+        """
+        )
+        with pytest.raises(InferenceError):
+            next(ast_node5.infer())
+
     @pytest.mark.xfail(reason="Does not support function metaclasses")
     def test_function_metaclasses(self):
         # These are not supported right now, although