[Cython] Bug in Cython producing incorrect C code

[mark florisson]

On 26 January 2012 18:53, Stefan Behnel <stefan_ml at behnel.de> wrote:
> mark florisson, 26.01.2012 16:20:
>> On 26 January 2012 06:39, Vitja Makarov wrote:
>>> 2012/1/25 Stefan Behnel:
>>>> Back to the old idea of separating the type analysis into 1) a basic
>>>> typing, inference and entry creation step and 2) a proper type analysis,
>>>> coercion, etc. step.
>>>>
>>>
>>> Yeah! I think the issue must be fixed before release. We can start
>>> moving slowly in this direction and split
>>> CascadedAssignmentNode.analyse_types into parts:
>>>  - normal analyse_types()/expressions()
>>>  - create clone nodes at some late stage
>>
>> At what stage would the stage 2) proper type analysis take place?
>
> After the structural optimisation phase and before any optimisations or
> other transforms that require complete type information but do not change
> types anymore. I don't see it being moved to the end of the pipeline, the
> results will be needed way before that. Even some optimisations may not be
> possible without complete type analysis.
>
>
>> Basically nodes may be replaced at any point, and I'm not sure you
>> want to wait until just before code generation to do the coercions
>> (e.g.  GILCheck won't catch coercions to object, although assignment
>> nodes seem to check manually).
>
> There's a large grey area in between. It'll need some refactoring and
> rebalancing, just as before. But it should be easier than it is now because
> the grey area will have more anchors in it.
>

That's nice. It wouldn't solve the problem at hand though, and I think
nothing can unless it will be at the very end of the pipeline.

>> I think this problem can trivially be solved by creating a ProxyNode
>> that should never be replaced by any transform, but it's argument may
>> be replaced. So you wrap self.rhs in a ProxyNode and use that to
>> create your CloneNodes.
>
> I can't see what a ProxyNode would do that a CloneNode shouldn't do anyway.

It wouldn't be a replacement, merely an addition (an extra indirection).

> Stefan
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