Issue #18259: Declare sethostname in socketmodule.c for AIX

Misc/NEWS

@@ -123,6 +123,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #18259: Declare sethostname in socketmodule.c for AIX
+
 - Issue #18147: Add diagnostic functions to ssl.SSLContext(). get_ca_list()
   lists all loaded CA certificates and cert_store_stats() returns amount of
   loaded X.509 certs, X.509 CA certs and CRLs.

Modules/socketmodule.c

@@ -4066,6 +4066,11 @@ socket_sethostname(PyObject *self, PyObject *args)
     Py_buffer buf;
     int res, flag = 0;
 
+#ifdef _AIX
+/* issue #18259, not declared in any useful header file */
+extern int sethostname(const char *, size_t);
+#endif
+
     if (!PyArg_ParseTuple(args, "S:sethostname", &hnobj)) {
         PyErr_Clear();
         if (!PyArg_ParseTuple(args, "O&:sethostname",