Issue #17715: Merge fix from 3.3.

Lib/test/test_int.py

@@ -354,6 +354,12 @@ class IntTestCases(unittest.TestCase):
                     return 42
             self.assertEqual(int(JustTrunc()), 42)
 
+            class ExceptionalTrunc(base):
+                def __trunc__(self):
+                    1 / 0
+            with self.assertRaises(ZeroDivisionError):
+                int(ExceptionalTrunc())
+
             for trunc_result_base in (object, Classic):
                 class Integral(trunc_result_base):
                     def __int__(self):

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.4.0 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #17715: Fix segmentation fault from raising an exception in a __trunc__
+  method.
+
 - Issue #17643: Add __callback__ attribute to weakref.ref.
 
 - Issue #16447: Fixed potential segmentation fault when setting __name__ on a

Objects/abstract.c

@@ -1314,6 +1314,8 @@ PyNumber_Long(PyObject *o)
         PyObject *truncated = PyEval_CallObject(trunc_func, NULL);
         PyObject *int_instance;
         Py_DECREF(trunc_func);
+        if (truncated == NULL)
+            return NULL;
         /* __trunc__ is specified to return an Integral type,
            but int() needs to return a int. */
         int_instance = convert_integral_to_int(truncated,