Index: Python/ast.c
===================================================================
--- Python/ast.c	(revision 64040)
+++ Python/ast.c	(working copy)
@@ -694,6 +694,9 @@
                     /* def foo((x)): is not complex, special case. */
                     if (NCH(ch) != 1) {
                         /* We have complex arguments, setup for unpacking. */
+                        if (Py_Py3kWarningFlag && !ast_warn(c, ch,
+                            "tuple parameter upacking has been removed in 3.x"))
+                            goto error;
                         asdl_seq_SET(args, k++, compiler_complex_args(c, ch));
                         if (!asdl_seq_GET(args, k-1))
                                 goto error;
Index: Lib/test/test_py3kwarn.py
===================================================================
--- Lib/test/test_py3kwarn.py	(revision 64039)
+++ Lib/test/test_py3kwarn.py	(working copy)
@@ -124,6 +124,12 @@
             with catch_warning() as w:
                 self.assertWarning(set(), w, expected)
 
+    def test_tuple_parameter_unpacking(self):
+        expected = "tuple parameter upacking has been removed in 3.x"
+        with catch_warning() as w:
+            exec "def f((a, b)): pass"
+            self.assertWarning(None, w, expected)
+
     def test_buffer(self):
         expected = 'buffer() not supported in 3.x; use memoryview()'
         with catch_warning() as w: