[BUG] metaclass=EnumMeta causes: PyTuple_GET_SIZE: Assertion PyTuple_Check(op)' failed`

[mgorny]

Describe the bug

The code snippet reproduced below built with Cython 3 (Cython 0.x is fine) produces a Python extension that crashes upon loading if CPython was built with assertions enabled:

$ python -c 'import repro'
python: ./Include/cpython/tupleobject.h:23: PyTuple_GET_SIZE: Assertion `PyTuple_Check(op)' failed.
Aborted (core dumped)

Backtrace

(gdb) bt
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1  0x00007fa5a2889e2f in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2  0x00007fa5a2839cc2 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007fa5a28224ed in __GI_abort () at abort.c:79
#4  0x00007fa5a2822415 in __assert_fail_base (fmt=0x7fa5a299fb98 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", 
    assertion=assertion@entry=0x7fa5a2f04da1 "PyTuple_Check(op)", file=file@entry=0x7fa5a2f1a450 "./Include/cpython/tupleobject.h", 
    line=line@entry=23, function=function@entry=0x7fa5a2f46710 <__PRETTY_FUNCTION__.8> "PyTuple_GET_SIZE") at assert.c:92
#5  0x00007fa5a28325e2 in __assert_fail (assertion=assertion@entry=0x7fa5a2f04da1 "PyTuple_Check(op)", 
    file=file@entry=0x7fa5a2f1a450 "./Include/cpython/tupleobject.h", line=line@entry=23, 
    function=function@entry=0x7fa5a2f46710 <__PRETTY_FUNCTION__.8> "PyTuple_GET_SIZE") at assert.c:101
#6  0x00007fa5a2d5249a in PyTuple_GET_SIZE (op=op@entry={}) at ./Include/cpython/tupleobject.h:23
#7  0x00007fa5a2d52678 in method_vectorcall (method=<optimized out>, args=0x7ffdb3ea2bd8, nargsf=<optimized out>, kwnames={})
    at Objects/classobject.c:64
#8  0x00007fa5a2af9c4b in __Pyx_PyObject_FastCallDict ()
   from /home/mgorny/git/cython-enummeta-repro/repro.cpython-311-x86_64-linux-gnu.so
#9  0x00007fa5a2afa1ea in __Pyx_Py3MetaclassPrepare ()
   from /home/mgorny/git/cython-enummeta-repro/repro.cpython-311-x86_64-linux-gnu.so
#10 0x00007fa5a2af8e57 in __pyx_pymod_exec_repro () from /home/mgorny/git/cython-enummeta-repro/repro.cpython-311-x86_64-linux-gnu.so
#11 0x00007fa5a2d97284 in PyModule_ExecDef (module=module@entry=<module at remote 0x7fa5a2ba0400>, 
    def=def@entry=0x7fa5a2aff280 <__pyx_moduledef>) at Objects/moduleobject.c:419
#12 0x00007fa5a2e554b3 in exec_builtin_or_dynamic (mod=mod@entry=<module at remote 0x7fa5a2ba0400>) at Python/import.c:2334
#13 0x00007fa5a2e55501 in _imp_exec_dynamic_impl (module=<optimized out>, mod=mod@entry=<module at remote 0x7fa5a2ba0400>)
    at Python/import.c:2408
#14 0x00007fa5a2e5550c in _imp_exec_dynamic (module=<optimized out>, mod=mod@entry=<module at remote 0x7fa5a2ba0400>)
    at Python/clinic/import.c.h:474
#15 0x00007fa5a2d952cd in cfunction_vectorcall_O (func=<built-in method exec_dynamic of module object at remote 0x7fa5a2b8a390>, 
    args=<optimized out>, nargsf=<optimized out>, kwnames=<optimized out>) at Objects/methodobject.c:514
#16 0x00007fa5a2d4fa71 in _PyVectorcall_Call (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, 
    func=0x7fa5a2d95264 <cfunction_vectorcall_O>, 
    callable=callable@entry=<built-in method exec_dynamic of module object at remote 0x7fa5a2b8a390>, 
    tuple=tuple@entry=(<module at remote 0x7fa5a2ba0400>,), kwargs=kwargs@entry={}) at Objects/call.c:245
#17 0x00007fa5a2d4fe22 in _PyObject_Call (tstate=0x7fa5a31856f8 <_PyRuntime+166328>, 
    callable=callable@entry=<built-in method exec_dynamic of module object at remote 0x7fa5a2b8a390>, 
    args=args@entry=(<module at remote 0x7fa5a2ba0400>,), kwargs=kwargs@entry={}) at Objects/call.c:328
#18 0x00007fa5a2d4fe74 in PyObject_Call (
    callable=callable@entry=<built-in method exec_dynamic of module object at remote 0x7fa5a2b8a390>, 
    args=args@entry=(<module at remote 0x7fa5a2ba0400>,), kwargs=kwargs@entry={}) at Objects/call.c:355
#19 0x00007fa5a2e207ef in do_call_core (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, 
    func=func@entry=<built-in method exec_dynamic of module object at remote 0x7fa5a2b8a390>, 
    callargs=callargs@entry=(<module at remote 0x7fa5a2ba0400>,), kwdict=kwdict@entry={}, use_tracing=0) at Python/ceval.c:7329
#20 0x00007fa5a2e2ce0c in _PyEval_EvalFrameDefault (tstate=0x7fa5a31856f8 <_PyRuntime+166328>, frame=0x7fa5a32f62e0, 
    throwflag=<optimized out>) at Python/ceval.c:5381
#21 0x00007fa5a2e2e00b in _PyEval_EvalFrame (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, 
    frame=frame@entry=0x7fa5a32f6078, throwflag=throwflag@entry=0) at ./Include/internal/pycore_ceval.h:73
#22 0x00007fa5a2e2e102 in _PyEval_Vector (tstate=0x7fa5a31856f8 <_PyRuntime+166328>, func=0x7fa5a2b4fce0, locals=locals@entry=0x0, 
    args=0x7ffdb3ea3010, argcount=<optimized out>, kwnames=0x0) at Python/ceval.c:6439
#23 0x00007fa5a2d4fef8 in _PyFunction_Vectorcall (func=<optimized out>, stack=<optimized out>, nargsf=<optimized out>, 
    kwnames=<optimized out>) at Objects/call.c:393
#24 0x00007fa5a2d50235 in _PyObject_VectorcallTstate (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, 
    callable=callable@entry=<function at remote 0x7fa5a2b4fce0>, args=args@entry=0x7ffdb3ea3010, nargsf=nargsf@entry=2, 
    kwnames=kwnames@entry=0x0) at ./Include/internal/pycore_call.h:92
#25 0x00007fa5a2d51241 in object_vacall (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, base=base@entry=0x0, 
    callable=<function at remote 0x7fa5a2b4fce0>, vargs=vargs@entry=0x7ffdb3ea3090) at Objects/call.c:819
#26 0x00007fa5a2d51374 in PyObject_CallMethodObjArgs (obj=0x0, name=<optimized out>) at Objects/call.c:879
#27 0x00007fa5a2e54ed7 in import_find_and_load (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, 
    abs_name=abs_name@entry='repro') at Python/import.c:1737
#28 0x00007fa5a2e5717e in PyImport_ImportModuleLevelObject (name=name@entry='repro', globals=<optimized out>, 
    locals=locals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, fromlist=fromlist@entry=None, 
    level=level@entry=0) at Python/import.c:1836
#29 0x00007fa5a2e1c6bd in import_name (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, frame=frame@entry=0x7fa5a32f6020, 
    name='repro', fromlist=fromlist@entry=None, level=level@entry=0) at Python/ceval.c:7429
#30 0x00007fa5a2e28487 in _PyEval_EvalFrameDefault (tstate=0x7fa5a31856f8 <_PyRuntime+166328>, frame=0x7fa5a32f6020, 
    throwflag=<optimized out>) at Python/ceval.c:3951
#31 0x00007fa5a2e2e00b in _PyEval_EvalFrame (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, 
    frame=frame@entry=0x7fa5a32f6020, throwflag=throwflag@entry=0) at ./Include/internal/pycore_ceval.h:73
#32 0x00007fa5a2e2e102 in _PyEval_Vector (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, func=func@entry=0x7fa5a2bd5f80, 
    locals=locals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, args=args@entry=0x0, 
    argcount=argcount@entry=0, kwnames=kwnames@entry=0x0) at Python/ceval.c:6439
#33 0x00007fa5a2e2e21d in PyEval_EvalCode (co=co@entry=<code at remote 0x7fa5a2b1f5d0>, 
    globals=globals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, 
    locals=locals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}) at Python/ceval.c:1154
#34 0x00007fa5a2e707ba in run_eval_code_obj (tstate=tstate@entry=0x7fa5a31856f8 <_PyRuntime+166328>, co=co@entry=0x7fa5a2b1f5d0, 
    globals=globals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, 
    locals=locals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}) at Python/pythonrun.c:1712
#35 0x00007fa5a2e70884 in run_mod (mod=mod@entry=0x56220890cf50, filename=<optimized out>, 
    globals=globals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, 
    locals=locals@entry={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, flags=flags@entry=0x7ffdb3ea3580, 
    arena=arena@entry=0x7fa5a2b1b7d0) at Python/pythonrun.c:1733
#36 0x00007fa5a2e73800 in PyRun_StringFlags (str=str@entry=0x7fa5a2bba840 "import repro\n", start=start@entry=257, 
    globals={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, 
    locals={'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <type at remote 0x5622088c0470>, '__spec__': None, '__annotations__': {}, '__builtins__': <module at remote 0x7fa5a2b88a90>}, flags=flags@entry=0x7ffdb3ea3580)
    at Python/pythonrun.c:1603
#37 0x00007fa5a2e7385d in PyRun_SimpleStringFlags (command=0x7fa5a2bba840 "import repro\n", flags=flags@entry=0x7ffdb3ea3580)
    at Python/pythonrun.c:487
#38 0x00007fa5a2e90487 in pymain_run_command (command=<optimized out>) at Modules/main.c:255
#39 0x00007fa5a2e90f4c in pymain_run_python (exitcode=exitcode@entry=0x7ffdb3ea3614) at Modules/main.c:592
#40 0x00007fa5a2e9127d in Py_RunMain () at Modules/main.c:680
#41 0x00007fa5a2e912fa in pymain_main (args=args@entry=0x7ffdb3ea3670) at Modules/main.c:710
#42 0x00007fa5a2e913c9 in Py_BytesMain (argc=<optimized out>, argv=<optimized out>) at Modules/main.c:734
#43 0x000056220831b16e in main (argc=<optimized out>, argv=<optimized out>) at ./Programs/python.c:15

Code to reproduce the behaviour:

from enum import IntEnum, EnumMeta


class Test(IntEnum, metaclass=EnumMeta):
    pass

Expected behaviour

No response

OS

Gentoo Linux amd64

Python version

3.11.5

Cython version

df4c9a4

Additional context

Originally reported to pythongssapi/python-gssapi#327.