Fix an issue where __ prefixed variables where not hidden when accessed from a class

Everything worked well when looking at it from an instance perspective.

jedi/evaluate/context/klass.py

@@ -38,6 +38,7 @@ py__doc__(include_call_signature:      Returns the docstring for a context.
 
 """
 from jedi._compatibility import use_metaclass
+from jedi.parser_utils import get_parent_scope
 from jedi.evaluate.cache import evaluator_method_cache, CachedMetaClass
 from jedi.evaluate import compiled
 from jedi.evaluate.lazy_context import LazyKnownContext
@@ -83,6 +84,22 @@ class ClassFilter(ParserTreeFilter):
         return [self.name_class(self.context, name, self._node_context)
                 for name in names]
 
+    def _equals_origin_scope(self):
+        node = self._origin_scope
+        while node is not None:
+            if node == self._parser_scope or node == self.context:
+                return True
+            node = get_parent_scope(node)
+        return False
+
+    def _access_possible(self, name):
+        return not name.value.startswith('__') or name.value.endswith('__') \
+            or self._equals_origin_scope()
+
+    def _filter(self, names):
+        names = super(ClassFilter, self)._filter(names)
+        return [name for name in names if self._access_possible(name)]
+
 
 class ClassContext(use_metaclass(CachedMetaClass, TreeContext)):
     """

test/completion/classes.py

@@ -417,6 +417,9 @@ class PrivateVar():
     def __private_func(self):
         return 1
 
+    #? int()
+    __private_func()
+
     def wrap_private(self):
         return self.__private_func()
 #? []
@@ -425,6 +428,8 @@ PrivateVar().__var
 PrivateVar().__var
 #? []
 PrivateVar().__private_func
+#? []
+PrivateVar.__private_func
 #? int()
 PrivateVar().wrap_private()