New submission from Victor Milovanov <lostfree...@gmail.com>:
I am trying to define a type in C, that derives from PyTypeObject. I want to override tp_clear. To do so properly, I should call base type's tp_clear and have it perform its cleanup steps. PyTypeObject has a tp_clear implementation: subtype_clear. Problem is, it assumes the instance it gets is of a type, that does not override PyTypeObject's tp_clear, and behaves incorrectly in 2 ways: 1) it does not perform the usual cleanup, because in this code base = type; while ((baseclear = base->tp_clear) == subtype_clear) the loop condition is immediately false, as my types overrode tp_clear 2) later on it calls baseclear on the same object. But because of the loop above baseclear actually points to my type's custom tp_clear implementation, which leads to reentry to that function (basically a stack overflow, unless there's a guard against it). ---------- components: C API messages: 402466 nosy: Victor Milovanov priority: normal severity: normal status: open title: subtype_clear can not be called from derived types type: behavior versions: Python 3.10, Python 3.11, Python 3.6, Python 3.7, Python 3.8, Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue45266> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
