issue28083: add IntFlag constants

Lib/socket.py

@@ -50,7 +50,7 @@ import _socket
 from _socket import *
 
 import os, sys, io, selectors
-from enum import IntEnum
+from enum import IntEnum, IntFlag
 
 try:
     import errno
@@ -80,6 +80,16 @@ IntEnum._convert(
         __name__,
         lambda C: C.isupper() and C.startswith('SOCK_'))
 
+IntFlag._convert(
+        'MsgFlag',
+        __name__,
+        lambda C: C.isupper() and C.startswith('MSG_'))
+
+IntFlag._convert(
+        'AddressInfo',
+        __name__,
+        lambda C: C.isupper() and C.startswith('AI_'))
+
 _LOCALHOST    = '127.0.0.1'
 _LOCALHOST_V6 = '::1'