ExecutedParams should never be additionally faked, even if they are the first params. They have been legitimately created by a caller.

jedi/evaluate/finder.py

@@ -296,7 +296,9 @@ class NameFinder(object):
 
         cls = func.parent.get_parent_until((pr.Class, pr.Function))
 
-        if isinstance(cls, pr.Class) and param.position_nr == 0:
+        from jedi.evaluate.param import ExecutedParam
+        if isinstance(cls, pr.Class) and param.position_nr == 0 \
+                and not isinstance(param, ExecutedParam):
             # This is where we add self - if it has never been
             # instantiated.
             if isinstance(self.scope, er.InstanceElement):

jedi/evaluate/param.py

@@ -356,7 +356,7 @@ def _gen_param_name_copy(func, var_args, param, keys=(), values=(), array_type=N
 
 
 def _error_argument_count(func, actual_count):
-    default_arguments = sum(1 for p in func.params if p.assignment_details)
+    default_arguments = sum(1 for p in func.params if p.assignment_details or p.stars)
 
     if default_arguments == 0:
         before = 'exactly '

jedi/evaluate/recursion.py

@@ -39,7 +39,7 @@ class RecursionDetector(object):
     def push_stmt(self, stmt):
         self.current = _RecursionNode(stmt, self.current)
         check = self._check_recursion()
-        if check:  # TODO remove False!!!!
+        if check:
             debug.warning('catched stmt recursion: %s against %s @%s', stmt,
                           check.stmt, stmt.start_pos)
             self.pop_stmt()

test/static_analysis/descriptors.py

@@ -0,0 +1,13 @@
+# classmethod
+class TarFile():
+    @classmethod
+    def open(cls, name, **kwargs):
+        return cls.taropen(name, **kwargs)
+
+    @classmethod
+    def taropen(cls, name, **kwargs):
+        return name
+
+
+# should just work
+TarFile.open('hallo')