bpo-46917: math.nan is now always available (GH-31793)

Author: vstinner

Doc/library/math.rst

@@ -649,6 +649,9 @@ Constants
    A floating-point "not a number" (NaN) value.  Equivalent to the output of
    ``float('nan')``.
 
+   .. versionchanged:: 3.11
+      It is now always available.
+
    .. versionadded:: 3.5
 
 

Doc/whatsnew/3.11.rst

@@ -254,6 +254,7 @@ inspect
 
 math
 ----
+
 * Add :func:`math.exp2`: return 2 raised to the power of x.
   (Contributed by Gideon Mitchell in :issue:`45917`.)
 
@@ -266,6 +267,9 @@ math
   ``inf``. Previously they raised :exc:`ValueError`. (Contributed by Mark
   Dickinson in :issue:`44339`.)
 
+* The :data:`math.nan` value is now always available.
+  (Contributed by Victor Stinner in :issue:`46917`.)
+
 
 operator
 --------

Misc/NEWS.d/next/Library/2022-03-10-14-47-16.bpo-46917.s19zcy.rst

@@ -0,0 +1 @@
+The :data:`math.nan` value is now always available. Patch by Victor Stinner.