[3.11] gh-95324: Emit a warning if an object doesn't call PyObject_GC_UnTrack during deallocation in debug mode (GH-95325)

Misc/NEWS.d/next/Core and Builtins/2022-07-27-14-05-07.gh-issue-95324.28Q5u7.rst

@@ -0,0 +1,2 @@
+Emit a warning in debug mode if an object does not call
+:c:func:`PyObject_GC_UnTrack` before deallocation. Patch by Pablo Galindo.

Modules/_abc.c

@@ -63,6 +63,7 @@ abc_data_clear(_abc_data *self)
 static void
 abc_data_dealloc(_abc_data *self)
 {
+ PyObject_GC_UnTrack(self);
  PyTypeObject *tp = Py_TYPE(self);
  (void)abc_data_clear(self);
  tp->tp_free(self);

Modules/_ctypes/cfield.c

@@ -279,6 +279,7 @@ PyCField_clear(CFieldObject *self)
 static void
 PyCField_dealloc(PyObject *self)
 {
+ PyObject_GC_UnTrack(self);
  PyCField_clear((CFieldObject *)self);
  Py_TYPE(self)->tp_free((PyObject *)self);
 }

Modules/_threadmodule.c

@@ -57,6 +57,7 @@ lock_traverse(lockobject *self, visitproc visit, void *arg)
 static void
 lock_dealloc(lockobject *self)
 {
+ PyObject_GC_UnTrack(self);
  if (self->in_weakreflist != NULL) {
  PyObject_ClearWeakRefs((PyObject *) self);
  }
@@ -333,6 +334,7 @@ rlock_traverse(rlockobject *self, visitproc visit, void *arg)
 static void
 rlock_dealloc(rlockobject *self)
 {
+ PyObject_GC_UnTrack(self);
  if (self->in_weakreflist != NULL)
  PyObject_ClearWeakRefs((PyObject *) self);
  /* self->rlock_lock can be NULL if PyThread_allocate_lock() failed

Modules/gcmodule.c

@@ -2347,6 +2347,13 @@ PyObject_GC_Del(void *op)
  size_t presize = _PyType_PreHeaderSize(((PyObject *)op)->ob_type);
  PyGC_Head *g = AS_GC(op);
  if (_PyObject_GC_IS_TRACKED(op)) {
+#ifdef Py_DEBUG
+ if (PyErr_WarnExplicitFormat(PyExc_ResourceWarning, "gc", 0,
+ "gc", NULL, "Object of type %s is not untracked before destruction",
+ ((PyObject*)op)->ob_type->tp_name)) {
+ PyErr_WriteUnraisable(NULL);
+ }
+#endif
  gc_list_remove(g);
  }
  GCState *gcstate = get_gc_state();

Modules/xxlimited.c

@@ -138,6 +138,7 @@ Xxo_finalize(PyObject *self_obj)
 static void
 Xxo_dealloc(PyObject *self)
 {
+ PyObject_GC_UnTrack(self);
  Xxo_finalize(self);
  PyTypeObject *tp = Py_TYPE(self);
  freefunc free = PyType_GetSlot(tp, Py_tp_free);

Objects/exceptions.c

@@ -3222,6 +3222,7 @@ MemoryError_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
  self = state->memerrors_freelist;
  self->args = PyTuple_New(0);
  /* This shouldn't happen since the empty tuple is persistent */
+
  if (self->args == NULL) {
  return NULL;
  }
@@ -3237,6 +3238,8 @@ MemoryError_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 static void
 MemoryError_dealloc(PyBaseExceptionObject *self)
 {
+ _PyObject_GC_UNTRACK(self);
+
  BaseException_clear(self);
 
  /* If this is a subclass of MemoryError, we don't need to
@@ -3246,8 +3249,6 @@ MemoryError_dealloc(PyBaseExceptionObject *self)
  return;
  }
 
- _PyObject_GC_UNTRACK(self);
-
  struct _Py_exc_state *state = get_exc_state();
  if (state->memerrors_numfree >= MEMERRORS_SAVE) {
  Py_TYPE(self)->tp_free((PyObject *)self);

Objects/weakrefobject.c

@@ -558,6 +558,7 @@ proxy_bool(PyWeakReference *proxy)
 static void
 proxy_dealloc(PyWeakReference *self)
 {
+ PyObject_GC_UnTrack(self);
  if (self->wr_callback != NULL)
  PyObject_GC_UnTrack((PyObject *)self);
  clear_weakref(self);