Python 3.11.0a2+ (heads/main:8a45ca542a, Nov 30 2021, 22:40:56) [Clang 13.0.0 (clang-1300.0.29.3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> help("modules")

Please wait a moment while I gather a list of all available modules...

/Users/iritkatriel/src/cpython/Lib/pkgutil.py:92: DeprecationWarning: The distutils package is deprecated and slated for removal in Python 3.12. Use setuptools or check PEP-632 for potential alternatives
__import__(info.name)
/Users/iritkatriel/src/cpython/Lib/pkgutil.py:92: DeprecationWarning: lib2to3 package is deprecated and may not be able to parse Python 3.10+
__import__(info.name)
test_sqlite3: testing with version '2.6.0', sqlite_version '3.32.3'
/Users/iritkatriel/src/cpython/Lib/distutils/command/build_ext.py:13: DeprecationWarning: The distutils.sysconfig module is deprecated, use sysconfig instead
from distutils.sysconfig import customize_compiler, get_python_version
zsh: segmentation fault ./python.exe

On the debugger:

>> help("modules")

Please wait a moment while I gather a list of all available modules...

/Users/iritkatriel/src/cpython/Lib/pkgutil.py:92: DeprecationWarning: The distutils package is deprecated and slated for removal in Python 3.12. Use setuptools or check PEP-632 for potential alternatives
__import__(info.name)
/Users/iritkatriel/src/cpython/Lib/pkgutil.py:92: DeprecationWarning: lib2to3 package is deprecated and may not be able to parse Python 3.10+
__import__(info.name)
test_sqlite3: testing with version '2.6.0', sqlite_version '3.32.3'
/Users/iritkatriel/src/cpython/Lib/distutils/command/build_ext.py:13: DeprecationWarning: The distutils.sysconfig module is deprecated, use sysconfig instead
from distutils.sysconfig import customize_compiler, get_python_version
Process 88596 stopped

• thread Support "bpo-" in Misc/NEWS #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
  frame #0: 0x0000000100160046 python.exe`_PyObject_GenericGetAttrWithDict(obj=0x0000000106acfa50, name=0x0000000100fe91c0, dict=0x0000000000000000, suppress=0) at object.c:1305:17
  1302 PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
  1303 if (values_ptr && *values_ptr) {
  1304 if (PyUnicode_CheckExact(name)) {
  -> 1305 assert(_PyObject_DictPointer(obj) == NULL);
  1306 res = _PyObject_GetInstanceAttribute(obj, *values_ptr, name);
  1307 if (res != NULL) {
  1308 goto done;
  Target 0: (python.exe) stopped.
  (lldb) p _PyObject_Dump(name)
  object address : 0x100fe91c0
  object refcount : 165
  object type : 0x10051aec0
  object type name: str
  object repr : 'string'
  (lldb) p _PyObject_Dump(_PyObject_DictPointer(obj))
  error: Execution was interrupted, reason: Attempted to dereference an invalid pointer..
  The process has been returned to the state before expression evaluation.
  (lldb) p _PyObject_Dump(obj)
  object address : 0x106acfa50
  object refcount : 7
  object type : 0x105add590
  object type name: _cffi_backend.FFI
  object repr : <_cffi_backend.FFI object at 0x106acfa50>

It works for me on 3.10.

It's failing in this assertion which was added in #28802 :

Works for me on Ubuntu.

Python 3.11.0a2+ (heads/main:0aa0bd0563, Dec  1 2021, 11:39:40) [GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> help("modules")

[lots of output, but no assertion failure or segfault]

>>

I note that your debug output includes _cffi_backend.FFI object
Is this a cffi bug?

When I say "cffi bug", I should say "is cffi not ported to 3.11 yet?"

Unable to reproduce on macOS 12 with latest 3.11 official build, and my most recent dev build (HEAD at b394af1).

Also unable to reproduce with HEAD at 49444fb.

I'm using MacOS 11.6.

Also unable to reproduce with HEAD at 8a45ca5. Perhaps it is related to your build/dev environment?

I'm unable to reproduce on macOS 11.6 as well (head at 49444fb).

• thread Support "bpo-" in Misc/NEWS #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
  frame #0: 0x000000010015fd26 python.exe`_PyObject_GenericGetAttrWithDict(obj=0x000000013feb7a50, name=0x0000000100fe9350, dict=0x0000000000000000, suppress=0) at object.c:1305:17
  1302 PyDictValues **values_ptr = _PyObject_ValuesPointer(obj);
  1303 if (values_ptr && *values_ptr) {
  1304 if (PyUnicode_CheckExact(name)) {
  -> 1305 assert(_PyObject_DictPointer(obj) == NULL);
  1306 res = _PyObject_GetInstanceAttribute(obj, *values_ptr, name);
  1307 if (res != NULL) {
  1308 goto done;
  Target 0: (python.exe) stopped.
  (lldb) p obj
  (PyObject *) $0 = 0x000000013feb7a50
  (lldb) p _PyObject_Dump((PyObject)obj->ob_type)
  object address : 0x13ff25590
  object refcount : 32
  object type : 0x100518680
  object type name: type
  object repr : <class '_cffi_backend.FFI'>
  (lldb) p (PyObject*)obj->ob_type
  (PyObject *) $1 = 0x000000013ff25590
  (lldb) p (PyObject*)obj->ob_type->tp_dict
  (PyObject *) $2 = 0x000000013fedd910
  (lldb) p _PyObject_Dump((PyObject*)obj->ob_type->tp_dict)
  object address : 0x13fedd910
  object refcount : 1
  object type : 0x100511d50
  object type name: dict
  object repr : {'__new__': <built-in method __new__ of type object at 0x13ff25590>, '__getattribute__': <slot wrapper '__getattribute__' of '_cffi_backend.FFI' objects>, '__init__': <slot wrapper '__init__' of '_cffi_backend.FFI' objects>, 'addressof': <method 'addressof' of '_cffi_backend.FFI' objects>, 'alignof': <method 'alignof' of '_cffi_backend.FFI' objects>, 'def_extern': <method 'def_extern' of '_cffi_backend.FFI' objects>, 'callback': <method 'callback' of '_cffi_backend.FFI' objects>, 'cast': <method 'cast' of '_cffi_backend.FFI' objects>, 'dlclose': <method 'dlclose' of '_cffi_backend.FFI' objects>, 'dlopen': <method 'dlopen' of '_cffi_backend.FFI' objects>, 'from_buffer': <method 'from_buffer' of '_cffi_backend.FFI' objects>, 'from_handle': <method 'from_handle' of '_cffi_backend.FFI' objects>, 'gc': <method 'gc' of '_cffi_backend.FFI' objects>, 'getctype': <method 'getctype' of '_cffi_backend.FFI' objects>, 'init_once': <method 'init_once' of '_cffi_backend.FFI' objects>, 'integer_const': <method 'integer_const' of '_cffi_backend.FFI' objects>, 'list_types': <method 'list_types' of '_cffi_backend.FFI' objects>, 'memmove': <method 'memmove' of '_cffi_backend.FFI' objects>, 'new': <method 'new' of '_cffi_backend.FFI' objects>, 'new_allocator': <method 'new_allocator' of '_cffi_backend.FFI' objects>, 'new_handle': <method 'new_handle' of '_cffi_backend.FFI' objects>, 'offsetof': <method 'offsetof' of '_cffi_backend.FFI' objects>, 'release': <method 'release' of '_cffi_backend.FFI' objects>, 'sizeof': <method 'sizeof' of '_cffi_backend.FFI' objects>, 'string': <method 'string' of '_cffi_backend.FFI' objects>, 'typeof': <method 'typeof' of '_cffi_backend.FFI' objects>, 'unpack': <method 'unpack' of '_cffi_backend.FFI' objects>, 'errno': <attribute 'errno' of '_cffi_backend.FFI' objects>, '__doc__': None, 'NULL': <cdata 'void *' NULL>, 'error': <class 'ffi.error'>, 'CType': <class '_cffi_backend.CType'>, 'CData': <class '_cffi_backend._CDataBase'>, 'buffer': <class '_cffi_backend.buffer'>, 'RTLD_LAZY': 1, 'RTLD_NOW': 2, 'RTLD_GLOBAL': 8, 'RTLD_LOCAL': 4, 'RTLD_NODELETE': 128, 'RTLD_NOLOAD': 16}
  (lldb) p (PyObject*)obj->ob_type->tp_dictoffset
  (PyObject *) $3 = NULL

Because the tp_dictoffset is 0, _PyObject_DictPointer(obj) returns NULL and in the assertion, where the return value is dereferenced, it crashes.

(Note: it's not that the assertion is failing, we don't get that far).

This looks like an issue with 3rd party software cffi. Are you using a fresh build of cffi? The internal ABI of an alpha build changes very often.

How do I check that?

The easiest way is to remove and rebuild 3rd party software.

Christian - that's what it was. I uninstalled cffi and now it works.