python
diff --git a/‎Lib/test/test_typing.py‎
Lines changed: 16 additions & 0 deletions b/‎Lib/test/test_typing.py‎
Lines changed: 16 additions & 0 deletions
diff --git a/‎Misc/NEWS.d/next/Library/2023-04-08-12-43-52.gh-issue-101162.yOCd_J.rst‎
Lines changed: 2 additions & 0 deletions b/‎Misc/NEWS.d/next/Library/2023-04-08-12-43-52.gh-issue-101162.yOCd_J.rst‎
Lines changed: 2 additions & 0 deletions
diff --git a/‎Objects/abstract.c‎
Lines changed: 1 addition & 1 deletion b/‎Objects/abstract.c‎
Lines changed: 1 addition & 1 deletion
diff --git a/‎Objects/genericaliasobject.c‎
Lines changed: 1 addition & 0 deletions b/‎Objects/genericaliasobject.c‎
Lines changed: 1 addition & 0 deletions
@@ -4091,6 +4091,22 @@ class C(Generic[T]): pass
         with self.assertRaises(TypeError):
             C[()]
 
+    def test_generic_subclass_checks(self):
+        for typ in [list[int], List[int],
+                    tuple[int, str], Tuple[int, str],
+                    typing.Callable[..., None],
+                    collections.abc.Callable[..., None]]:
+            with self.subTest(typ=typ):
+                self.assertRaises(TypeError, issubclass, typ, object)
+                self.assertRaises(TypeError, issubclass, typ, type)
+                self.assertRaises(TypeError, issubclass, typ, typ)
+                self.assertRaises(TypeError, issubclass, object, typ)
+
+                # isinstance is fine:
+                self.assertTrue(isinstance(typ, object))
+                # but, not when the right arg is also a generic:
+                self.assertRaises(TypeError, isinstance, typ, typ)
+
     def test_init(self):
         T = TypeVar('T')
         S = TypeVar('S')
 
@@ -0,0 +1,2 @@
+Forbid using :func:`builtins.issubclass` with :class:`types.GenericAlias` as
+the first argument.
@@ -2812,7 +2812,7 @@ object_issubclass(PyThreadState *tstate, PyObject *derived, PyObject *cls)
         return -1;
     }
 
-    /* Probably never reached anymore. */
+    /* Can be reached when infinite recursion happens. */
     return recursive_issubclass(derived, cls);
 }
 
 
@@ -626,6 +626,7 @@ ga_vectorcall(PyObject *self, PyObject *const *args,
 
 static const char* const attr_exceptions[] = {
     "__class__",
+    "__bases__",
     "__origin__",
     "__args__",
     "__unpacked__",
Original file line number	Diff line number	Diff line change
@@ -0,0 +1,2 @@
	1	+ Forbid using :func:`builtins.issubclass` with :class:`types.GenericAlias` as
	2	+ the first argument.
Original file line number	Diff line number	Diff line change
@@ -2812,7 +2812,7 @@ object_issubclass(PyThreadState tstate, PyObject derived, PyObject *cls)
2812	2812	return -1;
2813	2813	}
2814	2814
2815		- /* Probably never reached anymore. */
	2815	+ /* Can be reached when infinite recursion happens. */
2816	2816	return recursive_issubclass(derived, cls);
2817	2817	}
2818	2818