Assertion failure on interrupt when catching exception group

[chgnrdv]

This (maybe too made-up and detached from reality) repro causes assertion failure when executed on current main (32df540).
On 3.11 it warns about "lost sys.stderr" and terminates.

import time
import threading
import _thread

def f():
    try:
        f()
    except RecursionError:
        f()

def g():
    try:
        raise ValueError()
    except* ValueError:
        f()

def h():
    time.sleep(1)
    _thread.interrupt_main()

t = threading.Thread(target=h)
t.start()
g()
t.join()

Output:

python: Objects/typeobject.c:4183: _PyType_Lookup: Assertion `!PyErr_Occurred()' failed.
Aborted (core dumped)

Stack trace:

#0  0x00007ffff7d3f34c in __pthread_kill_implementation () from /usr/lib/libc.so.6
#1  0x00007ffff7cf24b8 in raise () from /usr/lib/libc.so.6
#2  0x00007ffff7cdc534 in abort () from /usr/lib/libc.so.6
#3  0x00007ffff7cdc45c in __assert_fail_base.cold () from /usr/lib/libc.so.6
#4  0x00007ffff7ceb116 in __assert_fail () from /usr/lib/libc.so.6
#5  0x000055555574ecd9 in _PyType_Lookup (type=type@entry=0x555555be5430, name=name@entry=0x555555bb7c10 <_PyRuntime+334480>)
    at Objects/typeobject.c:4183
#6  0x00005555557319e3 in _PyObject_GenericGetAttrWithDict (obj=0x7ffff77a7c90, name=0x555555bb7c10 <_PyRuntime+334480>, dict=dict@entry=0x0, 
    suppress=suppress@entry=1) at Objects/object.c:1266
#7  0x0000555555731d8d in _PyObject_LookupAttr (v=0x7ffff77a7c90, name=<optimized out>, result=result@entry=0x7ffffff40780) at Objects/object.c:933
#8  0x000055555582764c in print_exception_file_and_line (ctx=ctx@entry=0x7fffffffe270, value_p=value_p@entry=0x7ffffff40808)
    at Python/pythonrun.c:941
#9  0x0000555555827ed2 in print_exception (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff77a7c90) at Python/pythonrun.c:1209
#10 0x0000555555827fcc in print_exception_group (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff77a7c90) at Python/pythonrun.c:1377
#11 0x0000555555828418 in print_exception_recursive (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff77a7c90) at Python/pythonrun.c:1491
#12 0x0000555555828491 in print_chained (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff77a7c90, 
    message=message@entry=0x55555594b200 <context_message> "During handling of the above exception, another exception occurred:\n", 
    tag=tag@entry=0x5555558deda0 "context") at Python/pythonrun.c:1254
#13 0x000055555582868e in print_exception_cause_and_context (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff780e900)
    at Python/pythonrun.c:1344
#14 0x00005555558283d3 in print_exception_recursive (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff780e900) at Python/pythonrun.c:1482
#15 0x0000555555828491 in print_chained (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff780e900, 
    message=message@entry=0x55555594b200 <context_message> "During handling of the above exception, another exception occurred:\n", 
    tag=tag@entry=0x5555558deda0 "context") at Python/pythonrun.c:1254

...

#16186 0x000055555582868e in print_exception_cause_and_context (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff6be0ec0)
    at Python/pythonrun.c:1344
#16187 0x00005555558283d3 in print_exception_recursive (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff6be0ec0) at Python/pythonrun.c:1482
#16188 0x0000555555828491 in print_chained (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff6be0ec0,
    message=message@entry=0x55555594b200 <context_message> "During handling of the above exception, another exception occurred:\n",
    tag=tag@entry=0x5555558deda0 "context") at Python/pythonrun.c:1254
#16189 0x000055555582868e in print_exception_cause_and_context (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff6be0f30)
    at Python/pythonrun.c:1344
#16190 0x00005555558283d3 in print_exception_recursive (ctx=ctx@entry=0x7fffffffe270, value=value@entry=0x7ffff6be0f30) at Python/pythonrun.c:1482
#16191 0x0000555555828969 in _PyErr_Display (file=file@entry=0x7ffff79ba7b0, exception=exception@entry=0x555555a75160 <_PyExc_KeyboardInterrupt>,
    value=value@entry=0x7ffff6be0f30, tb=tb@entry=0x7ffff6c22ad0) at Python/pythonrun.c:1530
#16192 0x0000555555828ad3 in PyErr_Display (exception=0x555555a75160 <_PyExc_KeyboardInterrupt>, value=0x7ffff6be0f30, tb=0x7ffff6c22ad0)
    at Python/pythonrun.c:1562
#16193 0x0000555555835660 in sys_excepthook_impl (module=module@entry=0x7ffff7947f50, exctype=<optimized out>, value=<optimized out>,
    traceback=<optimized out>) at ./Python/sysmodule.c:748
#16194 0x00005555558356c6 in sys_excepthook (module=0x7ffff7947f50, args=args@entry=0x7fffffffe3f0, nargs=nargs@entry=3)
    at ./Python/clinic/sysmodule.c.h:102
#16195 0x000055555572c28c in cfunction_vectorcall_FASTCALL (func=0x7ffff7948470, args=0x7fffffffe3f0, nargsf=<optimized out>, kwnames=<optimized out>)
    at Objects/methodobject.c:422
#16196 0x00005555556e1aa0 in _PyObject_VectorcallTstate (tstate=0x555555bd8808 <_PyRuntime+468616>, callable=callable@entry=0x7ffff7948470,
    args=0x7fffffffe3f0, args@entry=0x7fffffffe360, nargsf=nargsf@entry=3, kwnames=kwnames@entry=0x0) at ./Include/internal/pycore_call.h:92
#16197 0x00005555556e1b90 in _PyObject_FastCallTstate (nargs=3, args=0x7fffffffe360, func=0x7ffff7948470, tstate=<optimized out>)
    at ./Include/internal/pycore_call.h:116
#16198 _PyObject_FastCall (func=func@entry=0x7ffff7948470, args=args@entry=0x7fffffffe3f0, nargs=nargs@entry=3) at Objects/call.c:310
#16199 0x0000555555828c2b in _PyErr_PrintEx (tstate=0x555555bd8808 <_PyRuntime+468616>, set_sys_last_vars=set_sys_last_vars@entry=1)
    at Python/pythonrun.c:813
#16200 0x0000555555828eb1 in PyErr_PrintEx (set_sys_last_vars=set_sys_last_vars@entry=1) at Python/pythonrun.c:861
#16201 0x0000555555828ec1 in PyErr_Print () at Python/pythonrun.c:867
#16202 0x00005555558293ab in _PyRun_SimpleFileObject (fp=fp@entry=0x555555bdb530, filename=filename@entry=0x7ffff77adbc0, closeit=closeit@entry=1,
    flags=flags@entry=0x7fffffffe508) at Python/pythonrun.c:439
#16203 0x000055555582951d in _PyRun_AnyFileObject (fp=fp@entry=0x555555bdb530, filename=filename@entry=0x7ffff77adbc0, closeit=closeit@entry=1,
    flags=flags@entry=0x7fffffffe508) at Python/pythonrun.c:78
#16204 0x00005555558487a5 in pymain_run_file_obj (program_name=program_name@entry=0x7ffff77c7370, filename=filename@entry=0x7ffff77adbc0,
    skip_source_first_line=0) at Modules/main.c:360
#16205 0x00005555558488cd in pymain_run_file (config=config@entry=0x555555bbd3c0 <_PyRuntime+356928>) at Modules/main.c:379
#16206 0x0000555555849063 in pymain_run_python (exitcode=exitcode@entry=0x7fffffffe684) at Modules/main.c:610
#16207 0x000055555584930f in Py_RunMain () at Modules/main.c:689
#16208 0x0000555555849386 in pymain_main (args=args@entry=0x7fffffffe6e0) at Modules/main.c:719
#16209 0x000055555584944c in Py_BytesMain (argc=<optimized out>, argv=<optimized out>) at Modules/main.c:743
#16210 0x0000555555651772 in main (argc=<optimized out>, argv=<optimized out>) at ./Programs/python.c:15

Linked PRs

• gh-102056: Fix a few bugs in error handling of exception printing code #102078

[iritkatriel]

You don’t get this with except?

[chgnrdv]

As far as i can see it fails only with except* <exc_type> if exc_type matches the type of exception raised in corresponding try statement.

[iritkatriel]

Thank you @chgnrdv .