On Mon, Jan 2, 2012 at 5:48 PM, Lisandro Dalcin <dalc...@gmail.com> wrote: > On 2 January 2012 22:37, Mansour Moufid <mansourmou...@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)"
I'm leaning towards declaring them as being the proper type to begin with; what's to be gained by declaring these extern values as enums (=const)? At least with the larger types we should do this to avoid patently incorrect behavior, and this way they would be consistant with the actual C for arithmetic promotion, etc. - Robert _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
