Add more details in warning message

Author: XuehaiPan

Doc/library/sys.rst

@@ -63,7 +63,7 @@ always available. Unless explicitly noted otherwise, all variables are read-only
       without changing the behavior:
 
       +---------------------------------------+---------------------------------------------------------------------+
-      | Code Prior to Python 3.14             | Code in Python 3.14-3.15                                            |
+      | Code prior to Python 3.14             | Code prior to Python 3.16 with the same behavior                    |
       +=======================================+=====================================================================+
       | ``sys.abiflags``                      | ``sys.abiflags``                                                    |
       +---------------------------------------+---------------------------------------------------------------------+

Python/sysmodule.c

@@ -75,10 +75,17 @@ module sys
 #include "clinic/sysmodule.c.h"
 
 
-#define WarnIncomingSysAbiflagsChange()                       \
-    PyErr_WarnEx(PyExc_DeprecationWarning,                    \
-        "sys.abiflags will be set to a meaningful value "     \
-        "on all platforms in Python 3.16 instead of absent",  \
+PyDoc_STRVAR(IncomingSysAbiflagsChange_msg,
+"sys.abiflags will be set to a meaningful value on all platforms "
+"in Python 3.16 instead of absent.\n\n"
+"Please consider using `warnings.simplefilter()` with the "
+"`warnings.catch_warnings()` context manager.\n"
+"Or update the code with `if sys.platform.startswith('win')` condition."
+);
+
+#define WarnIncomingSysAbiflagsChange()     \
+    PyErr_WarnEx(PyExc_DeprecationWarning,  \
+        IncomingSysAbiflagsChange_msg,      \
         /*stack_level=*/1)