Test failures on no-GIL interpreter macOS 26 ARM64 with UBSan

Bug report

Bug description:

Here's my Action file: https://github.com/clin1234/sanitizer-experiments/blob/main/.github/workflows/cpython.yml
Log: https://github.com/clin1234/sanitizer-experiments/actions/runs/26239722888/job/77222501727

On macOS 26 ARM64, with the following flags on Clang 22: CFLAGS='-fsanitize-address-use-after-scope -fsanitize-coverage=trace-cmp -fstack-clash-protection' GDBM_CFLAGS="-I$(brew --prefix gdbm)/include"
GDBM_LIBS="-L$(brew --prefix gdbm)/lib -lgdbm"
./configure
--with-undefined-behavior-sanitizer
--with-pydebug
--disable-gil
--enable-safety
--enable-slower-safety
--with-lto=yes
--config-cache
--prefix=/opt/python-dev
--disable-ipv6
--with-openssl="$(brew --prefix openssl@3.5)"

In particular, these tests fail:

• test.test_asyncio.test_streams: (test.test_asyncio.test_streams.StreamTests.test_unhandled_cancel) and (test.test_asyncio.test_streams.StreamTests.test_unhandled_exception) due to OSError: [Errno None] error while attempting to bind on address (30, b'\xc5\xe5\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'): bind(): bad family

  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/test_asyncio/test_streams.py", line 1225, in _basetest_unhandled_exceptions
    self.loop.run_until_complete(main())
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/asyncio/base_events.py", line 725, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/test_asyncio/test_streams.py", line 1218, in main
    server = await asyncio.start_server(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
        handle_echo, 'localhost', port)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/asyncio/streams.py", line 84, in start_server
    return await loop.create_server(factory, host, port, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/asyncio/base_events.py", line 1646, in create_server
    raise OSError(err.errno, msg) from None

• test_dict and test_embed: 76 failures from the same error:

Could not find platform independent libraries <prefix>
Could not find platform dependent libraries <exec_prefix>
WARN: Could not find the standard library directory! sys.prefix is set to /opt/python-dev, is this correct?
Fatal Python error: Failed to import encodings module
Python runtime state: core initialized
Exception ignored in the internal traceback machinery:
ModuleNotFoundError: No module named 'traceback'
ModuleNotFoundError: No module named 'encodings'

• (test.test_exception_group.DeepRecursionInSplitAndSubgroup.test_deep_split) and (test.test_exception_group.DeepRecursionInSplitAndSubgroup.test_deep_subgroup) with AssertionError: RecursionError not raised in tests test_deep_split
• test_list due to timeout:

(test.test_list.ListTest.test_repr_deep) ... Timeout (0:10:00)!
Thread 0x00000001f33b3080 (most recent call first):
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/case.py", line 245 in handle
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/case.py", line 835 in assertRaises
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/list_tests.py", line 69 in test_repr_deep
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/case.py", line 637 in _callTestMethod
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/case.py", line 691 in run
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/case.py", line 747 in __call__
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/suite.py", line 122 in run
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/suite.py", line 84 in __call__
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/suite.py", line 122 in run
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/suite.py", line 84 in __call__
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/unittest/runner.py", line 256 in run
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 84 in _run_suite
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 42 in run_unittest
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 162 in test_func
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 118 in regrtest_runner
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 165 in _load_run_test
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 210 in _runtest_env_changed_exc
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 319 in _runtest
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/single.py", line 348 in run_single_test
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/worker.py", line 99 in worker_process
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/worker.py", line 137 in main
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/test/libregrtest/worker.py", line 141 in <module>
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/runpy.py", line 87 in _run_code
  File "/Users/runner/work/sanitizer-experiments/sanitizer-experiments/Lib/runpy.py", line 201 in _run_module_as_main

== Tests result: FAILURE ==

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-150256

.github/workflows/cpython.yml の sanitizer workflow から始め、test_asyncio/test_streams.py、test_dict、test_embed、test_exception_group、test_list で失敗を再現します。結果をリンクされている PR gh-150256 と比較してください。この issue では要求する変更が 1 つに定義されていないため、完了には合意された修正と、報告されている sanitizer 設定で macOS ARM64 上の対象テストがパスすることが必要です。