I had the inheritance cycle stuff backwards. Oops!

Michael W. Hudson · Michael W. Hudson · commit caf17be1b788 · 2002-11-27T10:24:44.000Z
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
@@ -3452,6 +3452,7 @@ class E(D):
         pass
     d = D()
     e = E()
+    D.__bases__ = (C,)
     D.__bases__ = (C2,)
     vereq(d.meth(), 1)
     vereq(e.meth(), 1)
@@ -3492,6 +3493,13 @@ class L(list):
         # actually, we'll have crashed by here...
         raise TestFailed, "shouldn't be able to create inheritance cycles"
 
+    try:
+        D.__bases__ = (E,)
+    except TypeError:
+        pass
+    else:
+        raise TestFailed, "shouldn't be able to create inheritance cycles"
+
     # let's throw a classic class into the mix:
     class Classic:
         def meth2(self):
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
@@ -208,10 +208,12 @@ type_set_bases(PyTypeObject *type, PyObject *value, void *context)
 				type->tp_name, ob->ob_type->tp_name);
 			return -1;
 		}
-		if (PyType_IsSubtype(type, (PyTypeObject*)ob)) {
-			PyErr_SetString(PyExc_TypeError,
-		"a __bases__ item causes an inheritance cycle");
-			return -1;
+		if (PyType_Check(ob)) {
+			if (PyType_IsSubtype((PyTypeObject*)ob, type)) {
+				PyErr_SetString(PyExc_TypeError,
+			"a __bases__ item causes an inheritance cycle");
+				return -1;
+			}
 		}
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -208,10 +208,12 @@ type_set_bases(PyTypeObject type, PyObject value, void *context)`
`208`	`208`	`type->tp_name, ob->ob_type->tp_name);`
`209`	`209`	`return -1;`
`210`	`210`	`}`
`211`		`- if (PyType_IsSubtype(type, (PyTypeObject*)ob)) {`
`212`		`- PyErr_SetString(PyExc_TypeError,`
`213`		`- "a __bases__ item causes an inheritance cycle");`
`214`		`- return -1;`
	`211`	`+ if (PyType_Check(ob)) {`
	`212`	`+ if (PyType_IsSubtype((PyTypeObject*)ob, type)) {`
	`213`	`+ PyErr_SetString(PyExc_TypeError,`
	`214`	`+ "a __bases__ item causes an inheritance cycle");`
	`215`	`+ return -1;`
	`216`	`+ }`
`215`	`217`	`}`
`216`	`218`	`}`
`217`	`219`