[New-bugs-announce] [issue40608] PY3.8 GC segfault (Py_TRASHCAN_SAFE_BEGIN/END are not backwards compatible)

[Irit Katriel]

New submission from Irit Katriel <iritkatriel at yahoo.com>:

While migrating our codebase from python 3.7 to python 3.8, one of our unit tests segfaulted and I’ve narrowed it down to the change of typeobject.c in:

  commit 351c67416ba4451eb3928fa0b2e933c2f25df1a3
  Author: Jeroen Demeyer <J.Demeyer at UGent.be>
  Date:   Fri May 10 19:21:11 2019 +0200
  bpo-35983: skip trashcan for subclasses (GH-11841)   

It seems that Py_TRASHCAN_SAFE_BEGIN/END are not backwards compatible (as claimed in the comment above their definition in object.h).

This patch has a unit test that currently fails, along with the change in typeobject.c that restores the code that broke it: 

https://github.com/iritkatriel/cpython/commit/d962dd7f800fdaaeacd5748c6e3d38bf1f5053c1

I believe that this change needs to be pushed until the Py_TRASHCAN_SAFE_BEGIN/END are removed and all users are forced to migrate to the new Py_TRASHCAN_BEGIN/END.

----------
components: Interpreter Core
messages: 368740
nosy: iritkatriel, jdemeyer, pablogsal, pitrou
priority: normal
severity: normal
status: open
title: PY3.8 GC segfault  (Py_TRASHCAN_SAFE_BEGIN/END are not backwards compatible)
type: crash
versions: Python 3.8

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<https://bugs.python.org/issue40608>
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