[Cython] Bug in Cython producing incorrect C code

[Stefan Behnel]

mark florisson, 24.01.2012 14:53:
> On 24 January 2012 11:37, Konrad Hinsen 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.
> 
> 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.

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.

The type driven optimisations would then run in between the two. That would
simplify the optimisations (which would no longer have to unpack wrapped
nodes) and improve the type analysis because it could work with the
optimised types, e.g. return types of optimised builtin functions.

I'm not entirely sure where the type inference should run. It may make more
sense to move it after the tree optimisations to make use of optimised
function calls.

While we're at it, we should also replace the current type inference
mechanism with a control flow based one.

Sounds like a good topic for a Cython hacking workshop.

Stefan