Add __getattr__ checks with proper inheritance.

jedi/evaluate/representation.py

@@ -318,9 +318,10 @@ class Class(use_metaclass(CachedMetaClass, pr.IsScope)):
         return result + list(type_cls.get_defined_names())
 
     def get_subscope_by_name(self, name):
-        for sub in reversed(self.subscopes):
-            if sub.name.get_code() == name:
-                return sub
+        for s in [self] + self.get_super_classes():
+            for sub in reversed(s.subscopes):
+                if sub.name.get_code() == name:
+                    return sub
         raise KeyError("Couldn't find subscope.")
 
     def is_callable(self):

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