[issue46640] Python can now use the C99 NAN constant
STINNER Victor
report at bugs.python.org
Sat Feb 5 11:42:34 EST 2022
STINNER Victor <vstinner at python.org> added the comment:
> The big blocker here is that a platform that fully supports C99 might not define the "NAN" macro. I don't think we can require that NAN be defined in order for Python to build (which is what the PR currently does, if I'm understanding it correctly).
If a platform doesn't implement NaN, it should define the Py_NO_NAN macro:
/* Py_NAN
* A value that evaluates to a NaN. On IEEE 754 platforms INF*0 or
* INF/INF works. Define Py_NO_NAN in pyconfig.h if your platform
* doesn't support NaNs.
*/
#if !defined(Py_NAN) && !defined(Py_NO_NAN)
// Use C99 "NAN" constant: quiet Not-A-Number (when supported)
# define Py_NAN NAN
#endif
Or do you mean that a platform can support NaN but don't define the <math.h> NAN macro?
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<https://bugs.python.org/issue46640>
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