SystemError: <method-wrapper '__init__' of ast.AST-child object at ...> returned NULL without setting an exception

[hroncok]

Bug report

Bug description:

import ast


class File(ast.AST):
    _fields = ("xxx",)

    def __init__(self):
        super().__init__()


File()

Traceback (most recent call last):
  File ".../method_wrapper.py", line 11, in <module>
    File()
    ~~~~^^
  File ".../method_wrapper.py", line 8, in __init__
    super().__init__()
    ~~~~~~~~~~~~~~~~^^
SystemError: <method-wrapper '__init__' of File object at 0x7f923918cf10> returned NULL without setting an exception

This has happened since 3.13.0a5. Discovered via real usage in robotframework/robotframework#5091

CPython versions tested on:

3.13, CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-117266: Fix crashes on user-created AST subclasses #117276

[hroncok]

Possibly started with ed4dfd8

[hroncok]

Indeed, git bisect confirms this started with ed4dfd8.

[hroncok]

Using the debug build:

$ ./python -X dev  ~/tmp/method_wrapper.py
Fatal Python error: _Py_CheckFunctionResult: a function returned NULL without setting an exception
Python runtime state: initialized
SystemError: <method-wrapper '__init__' of File object at 0x7f50527c15a0> returned NULL without setting an exception

Current thread 0x00007f505ff43740 (most recent call first):
  File ".../method_wrapper.py", line 8 in __init__
  File ".../method_wrapper.py", line 11 in <module>
Aborted (core dumped)

[hroncok]

(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  0x00007ffff7d6e8a3 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2  0x00007ffff7d1c8ee in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007ffff7d048ff in __GI_abort () at abort.c:79
#4  0x00000000006270ee in fatal_error_exit (status=<optimized out>) at Python/pylifecycle.c:2817
#5  0x00000000006287d2 in fatal_error (fd=2, header=header@entry=1, 
    prefix=prefix@entry=0x6d5590 <__func__.23> "_Py_CheckFunctionResult", 
    msg=msg@entry=0x6d4fc8 "a function returned NULL without setting an exception", status=status@entry=-1)
    at Python/pylifecycle.c:2998
#6  0x000000000062883c in _Py_FatalErrorFunc (func=func@entry=0x6d5590 <__func__.23> "_Py_CheckFunctionResult", 
    msg=msg@entry=0x6d4fc8 "a function returned NULL without setting an exception") at Python/pylifecycle.c:3014
#7  0x00000000004aeaf3 in _Py_CheckFunctionResult (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0x7fffea4dd450, result=result@entry=0x0, where=where@entry=0x0) at Objects/call.c:43
#8  0x00000000004aef04 in _PyObject_MakeTpCall (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0x7fffea4dd450, args=args@entry=0x7ffff7fb80f8, nargs=<optimized out>, 
    keywords=keywords@entry=0x0) at Objects/call.c:252
#9  0x00000000004aefe5 in _PyObject_VectorcallTstate (tstate=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0x7fffea4dd450, args=args@entry=0x7ffff7fb80f8, nargsf=<optimized out>, 
    kwnames=kwnames@entry=0x0) at ./Include/internal/pycore_call.h:166
#10 0x00000000004af033 in PyObject_Vectorcall (callable=callable@entry=0x7fffea4dd450, 
    args=args@entry=0x7ffff7fb80f8, nargsf=<optimized out>, kwnames=kwnames@entry=0x0) at Objects/call.c:327
#11 0x00000000005b3cf5 in _PyEval_EvalFrameDefault (tstate=0x946250 <_PyRuntime+247824>, frame=0x7ffff7fb8090, 
    throwflag=0) at Python/generated_cases.c.h:817
#12 0x00000000005cb33e in _PyEval_EvalFrame (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    frame=<optimized out>, throwflag=throwflag@entry=0) at ./Include/internal/pycore_ceval.h:114
#13 0x00000000005cb451 in _PyEval_Vector (tstate=0x946250 <_PyRuntime+247824>, func=0x7fffea4d56d0, 
    locals=locals@entry=0x0, args=0x7fffffffcdf0, argcount=1, kwnames=0x0) at Python/ceval.c:1820
#14 0x00000000004aec45 in _PyFunction_Vectorcall (func=<optimized out>, stack=<optimized out>, 
    nargsf=<optimized out>, kwnames=<optimized out>) at Objects/call.c:413
#15 0x00000000004b01be in _PyObject_VectorcallDictTstate (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0x7fffea4d56d0, args=args@entry=0x7fffffffcdf0, nargsf=nargsf@entry=1, 
    kwargs=kwargs@entry=0x0) at Objects/call.c:135
#16 0x00000000004b0370 in _PyObject_Call_Prepend (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0x7fffea4d56d0, obj=obj@entry=0x7fffea4dd500, 
    args=args@entry=0x920b10 <_PyRuntime+94416>, kwargs=kwargs@entry=0x0) at Objects/call.c:504
#17 0x000000000052de1a in slot_tp_init (self=0x7fffea4dd500, args=0x920b10 <_PyRuntime+94416>, kwds=0x0)
    at Objects/typeobject.c:9355
#18 0x00000000005294f3 in type_call (self=self@entry=0xab6130, args=args@entry=0x920b10 <_PyRuntime+94416>, 
    kwds=kwds@entry=0x0) at Objects/typeobject.c:1789
#19 0x00000000004aedd2 in _PyObject_MakeTpCall (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0xab6130, args=args@entry=0x7ffff7fb8078, nargs=<optimized out>, 
    keywords=keywords@entry=0x0) at Objects/call.c:242
#20 0x00000000004aefe5 in _PyObject_VectorcallTstate (tstate=0x946250 <_PyRuntime+247824>, 
    callable=callable@entry=0xab6130, args=args@entry=0x7ffff7fb8078, nargsf=<optimized out>, 
    kwnames=kwnames@entry=0x0) at ./Include/internal/pycore_call.h:166
#21 0x00000000004af033 in PyObject_Vectorcall (callable=callable@entry=0xab6130, 
    args=args@entry=0x7ffff7fb8078, nargsf=<optimized out>, kwnames=kwnames@entry=0x0) at Objects/call.c:327
#22 0x00000000005b3cf5 in _PyEval_EvalFrameDefault (tstate=0x946250 <_PyRuntime+247824>, frame=0x7ffff7fb8020, 
    throwflag=0) at Python/generated_cases.c.h:817
#23 0x00000000005cb33e in _PyEval_EvalFrame (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    frame=<optimized out>, throwflag=throwflag@entry=0) at ./Include/internal/pycore_ceval.h:114
#24 0x00000000005cb451 in _PyEval_Vector (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    func=func@entry=0x7fffea469cd0, locals=locals@entry=0x7fffea4813d0, args=args@entry=0x0, 
    argcount=argcount@entry=0, kwnames=kwnames@entry=0x0) at Python/ceval.c:1820
#25 0x00000000005cb501 in PyEval_EvalCode (co=co@entry=0x7fffea5a25c0, globals=globals@entry=0x7fffea4813d0, 
    locals=locals@entry=0x7fffea4813d0) at Python/ceval.c:599
#26 0x000000000062d406 in run_eval_code_obj (tstate=tstate@entry=0x946250 <_PyRuntime+247824>, 
    co=co@entry=0x7fffea5a25c0, globals=globals@entry=0x7fffea4813d0, locals=locals@entry=0x7fffea4813d0) at Python/pythonrun.c:1291
#27 0x000000000062d5bb in run_mod (mod=mod@entry=0xa90ee0, filename=filename@entry=0x7fffea4cd850, 
    globals=globals@entry=0x7fffea4813d0, locals=locals@entry=0x7fffea4813d0, flags=flags@entry=0x7fffffffd3e8, 
    arena=arena@entry=0x7fffea4cab60, interactive_src=0x0, generate_new_source=0) at Python/pythonrun.c:1376
#28 0x000000000062dcfd in pyrun_file (fp=fp@entry=0xa29aa0, filename=filename@entry=0x7fffea4cd850, 
    start=start@entry=257, globals=globals@entry=0x7fffea4813d0, locals=locals@entry=0x7fffea4813d0, 
    closeit=closeit@entry=1, flags=0x7fffffffd3e8) at Python/pythonrun.c:1212
#29 0x000000000062f32e in _PyRun_SimpleFileObject (fp=fp@entry=0xa29aa0, 
    filename=filename@entry=0x7fffea4cd850, closeit=closeit@entry=1, flags=flags@entry=0x7fffffffd3e8)
    at Python/pythonrun.c:461
#30 0x000000000062f50e in _PyRun_AnyFileObject (fp=fp@entry=0xa29aa0, filename=filename@entry=0x7fffea4cd850, 
    closeit=closeit@entry=1, flags=flags@entry=0x7fffffffd3e8) at Python/pythonrun.c:77
#31 0x0000000000650d3c in pymain_run_file_obj (program_name=program_name@entry=0x7fffea4a2c40, 
    filename=filename@entry=0x7fffea4cd850, skip_source_first_line=0) at Modules/main.c:357
#32 0x0000000000650e48 in pymain_run_file (config=config@entry=0x921178 <_PyRuntime+96056>)
    at Modules/main.c:376
#33 0x000000000065160e in pymain_run_python (exitcode=exitcode@entry=0x7fffffffd54c) at Modules/main.c:628
#34 0x0000000000651836 in Py_RunMain () at Modules/main.c:707
#35 0x000000000065188a in pymain_main (args=args@entry=0x7fffffffd590) at Modules/main.c:737
#36 0x000000000065190a in Py_BytesMain (argc=<optimized out>, argv=<optimized out>) at Modules/main.c:761
#37 0x000000000041d84f in main (argc=<optimized out>, argv=<optimized out>) at ./Programs/python.c:15

[JelleZijlstra]

Thanks! I'll look into it.

[JelleZijlstra]

Fix in #117276. I'll add the "release-blocker" label because this is a regression and should be fixed before the next alpha.