Python 3.13.0b1: Segmentation fault when running tests

[befeleme]

On the current main branch in a 3.13.0b1 venv with libcst and test dependencies installed, there's a segmentation fault happening in test_funcdef.py

Details

$ python -m pytest                  
platform linux -- Python 3.13.0b1, pytest-8.2.0, pluggy-1.5.0
rootdir: ~/dev/libcst_
configfile: pyproject.toml
plugins: hypothesis-6.102.4
collected 2061 items                                                                                                  

libcst_/_nodes/tests/test_assert.py ..........                                                                  [  0%]
libcst_/_nodes/tests/test_assign.py .........................                                                   [  1%]
libcst_/_nodes/tests/test_atom.py ............................................................................. [  5%]
.........................................................s.                                                     [  8%]
libcst_/_nodes/tests/test_attribute.py .....                                                                    [  8%]
libcst_/_nodes/tests/test_await.py ..........                                                                   [  9%]
libcst_/_nodes/tests/test_binary_op.py ..................                                                       [  9%]
libcst_/_nodes/tests/test_boolean_op.py ........                                                                [ 10%]
libcst_/_nodes/tests/test_call.py .................................                                             [ 11%]
libcst_/_nodes/tests/test_classdef.py ..........................                                                [ 13%]
libcst_/_nodes/tests/test_comment.py ......                                                                     [ 13%]
libcst_/_nodes/tests/test_comparison.py .......................                                                 [ 14%]
libcst_/_nodes/tests/test_cst_node.py ............                                                              [ 15%]
libcst_/_nodes/tests/test_del.py .....                                                                          [ 15%]
libcst_/_nodes/tests/test_dict.py ..............s                                                               [ 16%]
libcst_/_nodes/tests/test_dict_comp.py ..........                                                               [ 16%]
libcst_/_nodes/tests/test_docstring.py ................                                                         [ 17%]
libcst_/_nodes/tests/test_else.py ..                                                                            [ 17%]
libcst_/_nodes/tests/test_empty_line.py .......                                                                 [ 17%]
libcst_/_nodes/tests/test_flatten_behavior.py ...                                                               [ 17%]
libcst_/_nodes/tests/test_for.py ............                                                                   [ 18%]
libcst_/_nodes/tests/test_funcdef.py ........................Fatal Python error: Segmentation fault

Current thread 0x00007f94a583e740 (most recent call first):
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/expression.py", line 1839 in _codegen_impl
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/base.py", line 300 in _codegen
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/expression.py", line 2052 in _codegen_impl
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/base.py", line 300 in _codegen
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/statement.py", line 1840 in _codegen_impl
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/base.py", line 300 in _codegen
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/module.py", line 136 in code_for_node
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/tests/base.py", line 114 in __assert_codegen
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/_nodes/tests/base.py", line 77 in validate_node
  File "~/dev/libcst_/libcst_/_nodes/tests/test_funcdef.py", line 748 in test_valid
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/libcst/testing/utils.py", line 86 in new_test
  File "/usr/lib64/python3.13/unittest/case.py", line 606 in _callTestMethod
  File "/usr/lib64/python3.13/unittest/case.py", line 651 in run
  File "/usr/lib64/python3.13/unittest/case.py", line 707 in __call__
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/unittest.py", line 343 in runtest
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/runner.py", line 173 in pytest_runtest_call
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/runner.py", line 241 in <lambda>
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/runner.py", line 341 in from_call
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/runner.py", line 240 in call_and_report
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/runner.py", line 135 in runtestprotocol
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/runner.py", line 116 in pytest_runtest_protocol
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/main.py", line 364 in pytest_runtestloop
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/main.py", line 339 in _main
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/main.py", line 285 in wrap_session
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/main.py", line 332 in pytest_cmdline_main
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/config/__init__.py", line 178 in main
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/_pytest/config/__init__.py", line 206 in console_main
  File "~/dev/libcst_/venv2/lib64/python3.13/site-packages/pytest/__main__.py", line 7 in <module>
  File "/usr/lib64/python3.13/runpy.py", line 88 in _run_code
  File "/usr/lib64/python3.13/runpy.py", line 198 in _run_module_as_main
[1]    1047370 segmentation fault (core dumped)  python -m pytest

When run separately, tests pass.

Details

$ python -m pytest libcst_/_nodes/tests/test_funcdef.py
================================================= test session starts =================================================
platform linux -- Python 3.13.0b1, pytest-8.2.0, pluggy-1.5.0
rootdir: ~/dev/libcst_
configfile: pyproject.toml
plugins: hypothesis-6.102.4
collected 110 items                                                                                                   

libcst_/_nodes/tests/test_funcdef.py .......................................................................... [ 67%]
...................................s                                                                            [100%]

=========================================== 109 passed, 1 skipped in 14.60s ===========================================