bpo-42576: Raise TypeError when passing in keyword arguments to GenericAlias (GH-23656)

Fidget-Spinner · web-flow · commit 804d6893b801 · 2020-12-05T08:02:14.000-08:00
Use `_PyArg_NoKeywords` instead of `_PyArg_NoKwnames` when checking the `kwds` tuple when creating `GenericAlias`. This fixes an interpreter crash when passing in keyword arguments to `GenericAlias`'s constructor.

Needs backport to 3.9.

Automerge-Triggered-By: GH:gvanrossum
diff --git a/Lib/test/test_genericalias.py b/Lib/test/test_genericalias.py
@@ -302,6 +302,11 @@ def test_weakref(self):
                 alias = t[int]
                 self.assertEqual(ref(alias)(), alias)
 
+    def test_no_kwargs(self):
+        # bpo-42576
+        with self.assertRaises(TypeError):
+            GenericAlias(bad=float)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-12-05-22-34-47.bpo-42576.lEeEl7.rst b/Misc/NEWS.d/next/Core and Builtins/2020-12-05-22-34-47.bpo-42576.lEeEl7.rst
@@ -0,0 +1,3 @@
+``types.GenericAlias`` will now raise a ``TypeError`` when attempting to
+initialize with a keyword argument.  Previously, this would cause the
+interpreter to crash.  Patch by Ken Jin.
diff --git a/Objects/genericaliasobject.c b/Objects/genericaliasobject.c
@@ -567,7 +567,7 @@ static PyGetSetDef ga_properties[] = {
 static PyObject *
 ga_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
-    if (!_PyArg_NoKwnames("GenericAlias", kwds)) {
+    if (!_PyArg_NoKeywords("GenericAlias", kwds)) {
         return NULL;
     }
     if (!_PyArg_CheckPositional("GenericAlias", PyTuple_GET_SIZE(args), 2, 2)) {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+``types.GenericAlias`` will now raise a ``TypeError`` when attempting to
	`2`	`+initialize with a keyword argument. Previously, this would cause the`
	`3`	`+interpreter to crash. Patch by Ken Jin.`
Original file line number	Diff line number	Diff line change
`@@ -567,7 +567,7 @@ static PyGetSetDef ga_properties[] = {`
`567`	`567`	`static PyObject *`
`568`	`568`	`ga_new(PyTypeObject type, PyObject args, PyObject *kwds)`
`569`	`569`	`{`
`570`		`- if (!_PyArg_NoKwnames("GenericAlias", kwds)) {`
	`570`	`+ if (!_PyArg_NoKeywords("GenericAlias", kwds)) {`
`571`	`571`	`return NULL;`
`572`	`572`	`}`
`573`	`573`	`if (!_PyArg_CheckPositional("GenericAlias", PyTuple_GET_SIZE(args), 2, 2)) {`