[Cython] Compilation failes if a class member is named "INFINITY"

[Michael]

Am 05.02.2015 um 10:44 schrieb Stefan Behnel:
> Michael schrieb am 05.02.2015 um 09:52:
>> Am 31.01.2015 um 19:48 schrieb Matthew Brett:
>>> On Fri, Jan 30, 2015 at 1:49 AM, Michael wrote:
>>>> if I try to compile the following minimal example:
>>>>
>>>> cdef class Test:
>>>>
>>>>     cdef readonly int INFINITY
>>>>
>>>> cython does not complain but gcc refuses with an error message:
>>>> In file included from /usr/include/math.h:38:0,
>>>>                  from /usr/include/python2.7/pyport.h:325,
>>>>                  from /usr/include/python2.7/Python.h:58,
>>>>                  from testinf.c:16:
>>>> testinf.c:433:7: error: field '__builtin_inff' declared as a function
>>>>    int INFINITY;
>>>>        ^
>>>> testinf.c: In function '__pyx_pf_7testinf_4Test_8INFINITY___get__':
>>>> testinf.c:569:50: error: expected identifier before '(' token
>>>>    __pyx_t_1 = __Pyx_PyInt_From_int(__pyx_v_self->INFINITY); if
>>>> (unlikely(!__pyx_t_1)) {__pyx_filename = __pyx_f[0]; __pyx_lineno = 10;
>>>> __pyx_clineno = __LINE__; goto __pyx_L1_error;}
>>>>                                                   ^
>>>> Apparently the name "INFINITY" is handled wrongly; any other variable
>>>> name seems to be fine.
>>>
>>> Maybe you hit the INFINITY gcc macro?
>>>
>>> http://www.gnu.org/software/libc/manual/html_node/Infinity-and-NaN.html
>>
>> Yes, that's probably the explanation. So should Cython do anything about
>> the problem, i.e. raise an exception if struct members are named like a
>> macro?
> 
> Cython cannot know about everything that the C compiler (or its
> preprocessor) will eventually see in its flat namespace. So, no, Cython
> can't generally solve this problem for you.
> 
> 
>> I don't know about the Cython internals, but I wonder why the name not
>> altered in the c file:
>>  struct __pyx_obj_7testinf_Test {
>>   PyObject_HEAD
>>   int INFINITY;
>> };
>> I would have expected something like "int __pyx_member_INFINITY"?
> 
> Python extension types are just structs at the C level, and struct member
> names cannot be mangled. Plus, when types are external or public (or even
> just redeclared somewhere else by someone else), foreign code may depend on
> struct fields of extension types as well. Builtin types are an example.
> 
Ok, that makes sense. I'll just choose a different name then. :-)

Michael


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