[Cython] Fix integer width constant names in stdint.pxd

[Lisandro Dalcin]

On 2 January 2012 22:37, Mansour Moufid <mansourmoufid at gmail.com> wrote:
> Now my issue is as follows.
>
> (I CCed the cython-users list if this question is more appropriate there.)
>
> I have a simple file, int.pyx:
>
> from libc.stdint cimport *
> print long(UINT8_MAX)
> print long(UINT16_MAX)
> print long(UINT32_MAX)
> print long(UINT64_MAX)
>
> with the usual setup.py stuff. Compiling and running:
>
> $ python setup.py build_ext --inplace
> ...
> int.c:566:3: warning: overflow in implicit constant conversion [-Woverflow]
> ...
> $ python -c 'import int'
> 255
> 65535
> -1
> -1
>
> So obviously there are overflows here. Checking int.c, I see:
>
>  /* "int.pyx":2
>  * from libc.stdint cimport *
>  * print long(UINT8_MAX)             # <<<<<<<<<<<<<<
>  * print long(UINT16_MAX)
>  * print long(UINT32_MAX)
>  */
>  __pyx_t_1 = PyInt_FromLong(UINT8_MAX);
>
> and so on...
>
> PyInt_FromLong is used for all these constants, regardless of
> signedness or width, so any argument larger than LONG_MAX overflows,
> *before* being converted to the arbitrary-size Python integer type.
>
> I don't know if this is a bug, or if I'm overlooking something. Is
> there a way for me to use these constants with Python's arbitrary-size
> integers?
>

All these constants are declared as "enum", so Cython promotes them to
"int". Once again, Cython should have something like a "const" type
qualifier to poperly declare these compile-time constants.

As workaround, you could explicitly cast the constants like this
"print long(<uint8_t>UINT8_MAX)"


-- 
Lisandro Dalcin
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