#3935: properly support list subclasses in the C impl. of bisect.

Patch reviewed by Raymond.

Lib/test/test_bisect.py

@@ -196,6 +196,17 @@ class TestInsort(unittest.TestCase):
     def test_backcompatibility(self):
         self.assertEqual(self.module.insort, self.module.insort_right)
 
+    def test_listDerived(self):
+        class List(list):
+            data = []
+            def insert(self, index, item):
+                self.data.insert(index, item)
+
+        lst = List()
+        self.module.insort_left(lst, 10)
+        self.module.insort_right(lst, 5)
+        self.assertEqual([5, 10], lst.data)
+
 class TestInsortPython(TestInsort):
     module = py_bisect
 

Misc/NEWS

@@ -20,6 +20,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #3935: Properly support list subclasses in bisect's C implementation.
+
 - Issue #4014: Don't claim that Python has an Alpha release status, in addition
   to claiming it is Mature.
 

Modules/_bisectmodule.c

@@ -82,7 +82,7 @@ insort_right(PyObject *self, PyObject *args, PyObject *kw)
 	index = internal_bisect_right(list, item, lo, hi);
 	if (index < 0)
 		return NULL;
-	if (PyList_Check(list)) {
+	if (PyList_CheckExact(list)) {
 		if (PyList_Insert(list, index, item) < 0)
 			return NULL;
 	} else {
@@ -183,7 +183,7 @@ insort_left(PyObject *self, PyObject *args, PyObject *kw)
 	index = internal_bisect_left(list, item, lo, hi);
 	if (index < 0)
 		return NULL;
-	if (PyList_Check(list)) {
+	if (PyList_CheckExact(list)) {
 		if (PyList_Insert(list, index, item) < 0)
 			return NULL;
 	} else {