SF bug #1155938: Missing None check for __init__().

Lib/test/test_descr.py

@@ -3965,6 +3965,18 @@ def vicious_descriptor_nonsense():
     import gc; gc.collect()
     vereq(hasattr(c, 'attr'), False)
 
+def test_init():
+    # SF 1155938
+    class Foo(object):
+        def __init__(self):
+            return 10
+    try:
+        Foo()
+    except TypeError:
+        pass
+    else:
+        raise TestFailed, "did not test __init__() for None return"
+
 
 def test_main():
     weakref_segfault() # Must be first, somehow
@@ -4058,6 +4070,7 @@ def test_main():
     carloverre()
     filefault()
     vicious_descriptor_nonsense()
+    test_init()
 
     if verbose: print "All OK"
 

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 2.5 alpha 1?
 Core and builtins
 -----------------
 
+- Bug #1155938: new style classes did not check that __init__() was
+  returning None.
+
 - Patch #802188: Report characters after line continuation character 
   ('\') with a specific error message.
 

Objects/typeobject.c

@@ -4753,6 +4753,12 @@ slot_tp_init(PyObject *self, PyObject *args, PyObject *kwds)
 	Py_DECREF(meth);
 	if (res == NULL)
 		return -1;
+	if (res != Py_None) {
+		PyErr_SetString(PyExc_TypeError,
+			   "__init__() should return None");
+		Py_DECREF(res);
+		return -1;
+	}
 	Py_DECREF(res);
 	return 0;
 }