Add __getattr__ checks with proper inheritance.

test/static_analysis/attribute_warnings.py

@@ -0,0 +1,24 @@
+"""
+Jedi issues warnings for possible errors if ``__getattr__``,
+``__getattribute__`` or ``setattr`` are used.
+"""
+
+
+class Cls():
+    def __getattr__(self, name):
+        return getattr(str, name)
+
+
+Cls().upper
+
+#! 6 warning attribute-error
+Cls().undefined
+
+
+class Inherited(Cls):
+    pass
+
+Inherited().upper
+
+#! 12 warning attribute-error
+Inherited().undefined