[Cython] Bug in Cython producing incorrect C code

[Vitja Makarov]

2012/1/24 mark florisson <markflorisson88 at gmail.com>:
> On 24 January 2012 18:30, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>> 2012/1/24 Robert Bradshaw <robertwb at math.washington.edu>:
>>> On Tue, Jan 24, 2012 at 6:09 AM, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>>>> 2012/1/24 mark florisson <markflorisson88 at gmail.com>:
>>>>> On 24 January 2012 11:37, Konrad Hinsen <konrad.hinsen at fastmail.net> wrote:
>>>>>> Compiling the attached Cython file produced the attached C file which
>>>>>> has errors in lines 532-534:
>>>>>>
>>>>>>  __pyx_v_self->xx = None;
>>>>>>  __pyx_v_self->yy = None;
>>>>>>  __pyx_v_self->zz = None;
>>>>>>
>>>>>> There is no C symbol "None", so this doesn't compile.
>>>>>>
>>>>>> I first noticed the bug in Cython 0.15, but it's still in the latest
>>>>>> revision from Github.
>>>>>>
>>>>>> Konrad.
>>>>>>
>>>>>> _______________________________________________
>>>>>> cython-devel mailing list
>>>>>> cython-devel at python.org
>>>>>> http://mail.python.org/mailman/listinfo/cython-devel
>>>>>>
>>>>>
>>>>> Hm, it seems the problem is that the call to the builtin float results
>>>>> in SimpleCallNode being replaced with PythonCApiNode, which then
>>>>> generates the result code, but the list of coerced nodes are
>>>>> CloneNodes of the original rhs, and CloneNode does not generate the
>>>>> result code of the original rhs (i.e. allocate and assign to a temp),
>>>>> which results in a None result.
>>>>>
>>>>> Maybe CascadedAssignmentNode should replace CloneNode.arg with the
>>>>> latest self.rhs in generate_assignment_code? I'm not entirely sure.
>>
>> Seems like a hack to me.
>>
>>>>
>>>>
>>>> May be it's better to run OptimizeBuiltinCalls before
>>>> AnalyseExpressionsTransform?
>>>
>>> Doesn't OptimizeBuiltinCalls take advantage of type information?
>>
>> Yes, it does :(
>>
>> So as Mark said the problem is CascadedAssignmentNode.coerced_rhs_list
>> is created before rhs is updated.
>>
>
> I think deferring the CloneNode creation to code generation time works
> (are there any known problem with doing type coercions at code
> generation time?).

Coercion errors at code generation time?

> E.g. save 'env' during analyse_types and in
> generate_assignment_code do
>
>    rhs = CloneNode(self.rhs).coerce_to(lhs.type, self.env)
>    rhs.generate_evaluation_code(code)
>    lhs.generate_assignment_code(rhs, code)
>
> Seems to work.
>

Yeah, that's better.


-- 
vitja.