Issue #16060: Fix a double DECREF in int() implementation. Thanks Serhiy Storchaka.

Lib/test/test_int.py

@@ -305,6 +305,18 @@ class IntTestCases(unittest.TestCase):
                     self.fail("Failed to raise TypeError with %s" %
                               ((base, trunc_result_base),))
 
+                # Regression test for bugs.python.org/issue16060.
+                class BadInt(trunc_result_base):
+                    def __int__(self):
+                        return 42.0
+
+                class TruncReturnsBadInt(base):
+                    def __trunc__(self):
+                        return BadInt()
+
+                with self.assertRaises(TypeError):
+                    int(TruncReturnsBadInt())
+
     def test_error_message(self):
         testlist = ('\xbd', '123\xbd', '  123 456  ')
         for s in testlist:

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.3.1?
 Core and Builtins
 -----------------
 
+- Issue #16060: Fix refcounting bug when __trunc__ returns an object
+  whose __int__ gives a non-integer.  Patch by Serhiy Storchaka.
+
 - Issue #16046: Fix loading sourceless legacy pyos.
 
 - Issue #15379: Fix passing of non-BMP characters as integers for the charmap

Objects/abstract.c

@@ -1228,11 +1228,10 @@ convert_integral_to_int(PyObject *integral, const char *error_format)
     nb = Py_TYPE(integral)->tp_as_number;
     if (nb->nb_int) {
         PyObject *as_int = nb->nb_int(integral);
+        if (!as_int || PyLong_Check(as_int)) {
             Py_DECREF(integral);
-        if (!as_int)
-            return NULL;
-        if (PyLong_Check(as_int))
             return as_int;
+        }
         Py_DECREF(as_int);
     }
     PyErr_Format(PyExc_TypeError, error_format, Py_TYPE(integral)->tp_name);