[Cython] 'local variable referenced before assignment' warnings

Robert Bradshaw robertwb at math.washington.edu
Fri Sep 23 01:40:45 CEST 2011


On Thu, Sep 22, 2011 at 5:08 AM, Vitja Makarov <vitja.makarov at gmail.com> wrote:
> 2011/9/22 Robert Bradshaw <robertwb at math.washington.edu>:
>> On Wed, Sep 21, 2011 at 1:20 AM,  <robert.rex at exasol.com> wrote:
>>> Hi Robert,
>>>
>>> Robert Bradshaw wrote:
>>>>
>>>> The warning seem correct to me, or is foo actually modifying the
>>>> values of cya and cyb? (I suppose this could be possible by taking the
>>>> address of the "passed by reference" arguments, but would seem like a
>>>> *very* poor API design.)
>>>
>>> thanks for your fast answer! What made me came up with this issue is
>>> that GCC/C++ will not complain in similar situations in C++ code (and
>>> assumes foo() to initialize/change the value of cya/cyb). Thus, there
>>> is an (arguable) difference in C++ compiler/Cython warnings.
>>
>> Yes, in C++ the called function can modify values passed by reference,
>> so we need to add this exception to Cython.
>>
>
> That could be hard because we can not always resolve function to check
> its args at create-control-flow stage.

Doesn't this always happen after declaration analysis?

- Robert


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