gh-119613: deprecate Py_IS_NAN/INFINITY and Py_IS_FINITE

Doc/whatsnew/3.14.rst

@@ -103,7 +103,9 @@ Optimizations
 Deprecated
 ==========
 
-
+* Deprecate ``Py_IS_NAN``, ``Py_IS_INFINITY`` and ``Py_IS_FINITE`` macroses,
+  use instead ``isnan``, ``isinf`` and ``isfinite`` available from ``<math.h>``
+  since C99.  (Contributed by Sergey B Kirpichev in :gh:`119613`.)
 
 Removed
 =======

Include/pymath.h

@@ -27,6 +27,10 @@
 #define Py_MATH_TAU 6.2831853071795864769252867665590057683943L
 #endif
 
+/* Py_IS_NAN, Py_IS_INFINITY and Py_IS_FINITE are deprecated
+ * since CPython 3.14.
+ */
+
 // Py_IS_NAN(X)
 // Return 1 if float or double arg is a NaN, else 0.
 #define Py_IS_NAN(X) isnan(X)