From d91d4de31745fc1ed4c7e6c208917827c9c472b6 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@redhat.com>
Date: Mon, 9 Sep 2019 17:44:59 +0200
Subject: bpo-38070: visit_decref() calls _PyObject_IsFreed() (GH-15782)

In debug mode, visit_decref() now calls _PyObject_IsFreed() to ensure
that the object is not freed. If it's freed, the program fails with
an assertion error and Python dumps informations about the freed
object.
---
 Modules/gcmodule.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 134f6d1..f6e841d 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -376,6 +376,8 @@ static int
 visit_decref(PyObject *op, void *data)
 {
     assert(op != NULL);
+    _PyObject_ASSERT(op, !_PyObject_IsFreed(op));
+
     if (PyObject_IS_GC(op)) {
         PyGC_Head *gc = AS_GC(op);
         /* We're only interested in gc_refs for objects in the
-- 
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