[New-bugs-announce] [issue39016] Negative Refcount in Python 3.8

Christian Tismer report at bugs.python.org
Tue Dec 10 10:37:03 EST 2019

New submission from Christian Tismer <tismer at stackless.com>:

By the new Py_TPFLAGS_METHOD_DESCRIPTOR flag, a new code path is
activated, and when extension types like PySide create a new
class, we observe negative refcounts.

The reason is that the code in typeobject.c fkt. type_mro_modified
calls lookup_maybe_method which returns a _borrowed_ reference.
This happens in the "if (custom) {" branch.

Removing all Py_XDECREF calls from the function fixes that.

components: Extension Modules
messages: 358198
nosy: Christian.Tismer
priority: critical
severity: normal
status: open
title: Negative Refcount in Python 3.8
type: crash
versions: Python 3.8

Python tracker <report at bugs.python.org>

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