From 804d6893b801e8f30318afc38c20d4d0e6161db3 Mon Sep 17 00:00:00 2001
From: kj <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Sat, 5 Dec 2020 23:02:14 +0700
Subject: [PATCH] bpo-42576: Raise TypeError when passing in keyword arguments
 to GenericAlias (GH-23656)

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
---
 Lib/test/test_genericalias.py                                | 5 +++++
 .../2020-12-05-22-34-47.bpo-42576.lEeEl7.rst                 | 3 +++
 Objects/genericaliasobject.c                                 | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2020-12-05-22-34-47.bpo-42576.lEeEl7.rst

diff --git a/Lib/test/test_genericalias.py b/Lib/test/test_genericalias.py
index 912fb33af1a..c113e538248 100644
--- a/Lib/test/test_genericalias.py
+++ b/Lib/test/test_genericalias.py
@@ -302,6 +302,11 @@ class BaseTest(unittest.TestCase):
                 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
new file mode 100644
index 00000000000..7290b47dcc1
--- /dev/null
+++ 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
index 6102e05c165..51a12377b7e 100644
--- 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)) {