[New-bugs-announce] [issue34543] _struct.Struct: calling functions without calling __init__ results in SystemError

[DeKrain]

New submission from DeKrain <dawidkrainski8 at gmail.com>:

>>> from _struct import Struct
>>> s = Struct.__new__(Struct)
>>> s.unpack_from(b'asdf')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
SystemError: /Objects/tupleobject.c:84: Bad argument to internal function

In Modules/_struct.c:

static PyObject *
s_unpack_internal(PyStructObject *soself, const char *startfrom) {
...
PyObject *result = PyTuple_New(soself->s_len);
// soself->s_len is -1, set in Struct.__new__

----------
components: Extension Modules
messages: 324330
nosy: DeKrain
priority: normal
severity: normal
status: open
title: _struct.Struct: calling functions without calling __init__ results in SystemError
type: behavior
versions: Python 3.7

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue34543>
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