bpo-45061: Detect Py_DECREF(Py_True) bug (GH-28089)
Add a deallocator to the bool type to detect refcount bugs in C
extensions which call Py_DECREF(Py_True) or Py_DECREF(Py_False) by
mistake.
diff --git a/Misc/NEWS.d/next/C API/2021-08-31-15-21-36.bpo-45061.ZH0HVe.rst b/Misc/NEWS.d/next/C API/2021-08-31-15-21-36.bpo-45061.ZH0HVe.rst
new file mode 100644
index 0000000..58bd534
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2021-08-31-15-21-36.bpo-45061.ZH0HVe.rst
@@ -0,0 +1,3 @@
+Add a deallocator to the :class:`bool` type to detect refcount bugs in C
+extensions which call ``Py_DECREF(Py_True);`` or ``Py_DECREF(Py_False);`` by
+mistake. Patch by Victor Stinner.
diff --git a/Objects/boolobject.c b/Objects/boolobject.c
index b786966..bc1666f 100644
--- a/Objects/boolobject.c
+++ b/Objects/boolobject.c
@@ -153,6 +153,13 @@ static PyNumberMethods bool_as_number = {
0, /* nb_index */
};
+static void _Py_NO_RETURN
+bool_dealloc(PyObject* Py_UNUSED(ignore))
+{
+ Py_FatalError("deallocating True or False likely caused by "
+ "a refcount bug in a C extension");
+}
+
/* The type object for bool. Note that this cannot be subclassed! */
PyTypeObject PyBool_Type = {
@@ -160,7 +167,7 @@ PyTypeObject PyBool_Type = {
"bool",
sizeof(struct _longobject),
0,
- 0, /* tp_dealloc */
+ bool_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
diff --git a/Objects/object.c b/Objects/object.c
index 446c974..026262b 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1560,14 +1560,11 @@ none_repr(PyObject *op)
return PyUnicode_FromString("None");
}
-/* ARGUSED */
static void _Py_NO_RETURN
-none_dealloc(PyObject* ignore)
+none_dealloc(PyObject* Py_UNUSED(ignore))
{
- /* This should never get called, but we also don't want to SEGV if
- * we accidentally decref None out of existence.
- */
- Py_FatalError("deallocating None");
+ Py_FatalError("deallocating None likely caused by a refcount bug "
+ "in a C extension");
}
static PyObject *
