[Cython] new arrayarray.h header file not C99 compatible

[Stefan Behnel]

Hi,

I'm getting test build failures with the new arrayarray.h header file when
I enable "--std=c89" or "c99" in the CFLAGS:

"""
memoryview_inplace_division.c:877: warning: declaration does not declare
anything
memoryview_inplace_division.c:893: warning: declaration does not declare
anything
memoryview_inplace_division.c: In function ‘newarrayobject’:
memoryview_inplace_division.c:929: error: ‘arrayobject’ has no member named
‘ob_item’
...
"""

The lines it warns about (and which trigger the subsequent errors) are the
following union declarations:

"""
typedef struct arrayobject {
    PyObject_HEAD
    union {
        Py_ssize_t ob_size, length;
    };
    union {
        char *ob_item;
        float *_f;
        double *_d;
        int *_i;
        unsigned *_I;
        unsigned char *_B;
        signed char *_b;
        char *_c;
        unsigned long *_L;
        long *_l;
        short *_h;
        unsigned short *_H;
        Py_UNICODE *_u;
        void *_v;
    };
...
"""

Apparently, anonymous unions only became part of the C standard in C11:

http://stackoverflow.com/questions/3228104/anonymous-union-within-struct-not-in-c99

That's unfortunate, but I think we'd best give the unions a name (and let
users change all code that uses them ...).

BTW, is there any reason we have a "length" field at all? Shouldn't we be
using Py_SIZE() ?

Stefan