[Cython] cython-devel-tests-pyregr regression

[Vitja Makarov]

2012/8/23 Stefan Behnel <stefan_ml at behnel.de>:
> Vitja Makarov, 23.08.2012 07:42:
>> 2012/8/23 Vitja Makarov:
>>> 2012/8/23 Vitja Makarov:
>>>> 2012/8/23 Stefan Behnel:
>>>>> Vitja Makarov, 23.08.2012 07:03:
>>>>>> 2012/8/23 Stefan Behnel:
>>>>>>> Vitja Makarov, 22.08.2012 22:34:
>>>>>>>> 2012/8/23 Stefan Behnel:
>>>>>>>>> Vitja Makarov, 22.08.2012 22:11:
>>>>>>>>>> I've found regression:
>>>>>>>>>>
>>>>>>>>>> https://sage.math.washington.edu:8091/hudson/job/cython-devel-tests-pyregr/
>>>>>>>>>
>>>>>>>>> Interesting. It's a Py2 list comprehension in a class body that's failing here:
>>>>>>>>>
>>>>>>>>> """
>>>>>>>>>  class TestHelpSubparsersOrdering(HelpTestCase):
>>>>>>>>>      subparsers_signatures = [Sig(name=name)
>>>>>>>>>                               for name in ('a', 'b', 'c', 'd', 'e')]
>>>>>>>>>  """
>>>>>>>>>
>>>>>>>>> I wonder why "name" isn't declared as a variable yet at the point where it
>>>>>>>>> is being looked up in the function call.
>>>>>>>>
>>>>>>>>     def lookup_relative(self, name, pos):
>>>>>>>>         if name == "name":
>>>>>>>>             print name
>>>>>>>>             from ipdb import set_trace; set_trace()
>>>>>>>>         entry = self.lookup_here(name)
>>>>>>>>         if entry is not None and entry.pos[1:] <= pos[1:]: # Lookup fails here
>>>>>>>>             return entry
>>>>>>>>         if self.outer_scope:
>>>>>>>>             return self.outer_scope.lookup_relative(name, pos)
>>>>>>>>         return None
>>>>>>>>
>>>>>>>> What is that comparison for?
>>>>>>>
>>>>>>> Ah, yes, it is wrong in this context. It was meant to prevent names defined
>>>>>>> further down in the class body from being considered assignments to the
>>>>>>> name being looked up. Class bodies are not function bodies, assignments in
>>>>>>> them do not make a name "local". As long as it's not assigned, it's not
>>>>>>> defined and must be looked up in the outer scope.
>>>>>>
>>>>>> Do you remember this ticket #671
>>>>>>
>>>>>> If there is assignment in the class body we first lookup in the class
>>>>>> dict and then in globals.
>>>>>>
>>>>>> B = 0
>>>>>> def foo():
>>>>>>     B = 1
>>>>>>     class Foo():
>>>>>>         A = B
>>>>>>         B = B
>>>>>>     class Bar():
>>>>>>         A = B
>>>>>>     print Foo.A, Foo.B, Bar.A
>>>>>> foo()
>>>>>>
>>>>>> prints "0 0 1"
>>>>>
>>>>> In the case at hand, it's not an assignment but a method declaration. Maybe
>>>>> that makes a difference.
>>>>>
>>>>> In any case, this needs some more investigation than I did for my change. I
>>>>> think it can be rolled back completely.
>>>
>>> I've reverted your commit and here is my fix:
>>> https://github.com/vitek/cython/commit/198f254f62360b61c895ba68be0f4dbe07444449
>>>
>>> Cause of different class scope lookup rules I think we can't fully
>>> trust CF here.
>>
>> Another (maybe better) solution is to fix CF. It mustn't set
>> cf_maybe_null to False at class scope based on reference success.
>
> I've pushed these changes to the master for now. They are correct, even if
> we decide to improve the control flow decisions here (which would only lead
> to the same effect anyway).
>

Ok, I'll take a look later.

-- 
vitja.