Issue #17765: weakref.ref() no longer silently ignores keyword arguments.

Patch by Georg Brandl.

Lib/test/test_weakref.py

@@ -133,6 +133,10 @@ class ReferencesTestCase(TestBase):
         ref1 = weakref.ref(c, callback)
         del c
 
+    def test_constructor_kwargs(self):
+        c = C()
+        self.assertRaises(TypeError, weakref.ref, c, callback=None)
+
     def test_proxy_ref(self):
         o = C()
         o.bar = 1

Misc/NEWS

@@ -265,6 +265,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #17765: weakref.ref() no longer silently ignores keyword arguments.
+  Patch by Georg Brandl.
+
 - Issue #26873: xmlrpc now raises ResponseError on unsupported type tags
   instead of silently return incorrect result.
 

Objects/weakrefobject.c

@@ -268,7 +268,6 @@ static int
 parse_weakref_init_args(const char *funcname, PyObject *args, PyObject *kwargs,
                         PyObject **obp, PyObject **callbackp)
 {
-    /* XXX Should check that kwargs == NULL or is empty. */
     return PyArg_UnpackTuple(args, funcname, 1, 2, obp, callbackp);
 }
 
@@ -331,6 +330,9 @@ weakref___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 {
     PyObject *tmp;
 
+    if (!_PyArg_NoKeywords("ref()", kwargs))
+        return -1;
+
     if (parse_weakref_init_args("__init__", args, kwargs, &tmp, &tmp))
         return 0;
     else