ctypes.util.dllist is no longer used on Windows and macOS (Python 3.14+) #3

joblib#250 moved the ctypes.util.dllist import to module level and changed its condition:

# 3.7.0, in _load_libraries
if sys.platform not in ("linux", "emscripten"):
    from ctypes.util import dllist

# master, module level (since #250)
if sys.platform != "emscripten" and (
    # Python 3.15 doesn't have the CFUNCTYPE anymore:
    sys.platform == "linux" and sys.version_info[:2] >= (3, 15)
):
    from ctypes.util import dllist

The new condition is only true on Linux with Python 3.15+, so dllist is now always None on Windows and macOS (permalink). On Python 3.14+, _load_libraries falls back to the Toolhelp enumerator on Windows and to _dyld_* on macOS. 3.7.0 used dllist there (joblib#219, and the 3.7.0 changelog says so).

Checked on macOS arm64, Python 3.14.4, by recording which _find_libraries_* method _load_libraries calls:

3.7.0      darwin 3.14.4 -> ['_find_libraries_with_python']
3.8.0.dev0 darwin 3.14.4 -> ['_find_libraries_with_dyld']

The comment in the condition is about Linux, and the description of joblib#250 only discusses Linux. This looks unintended rather than a decision to stop using dllist on Windows and macOS.

Consequences:

• Nothing breaks: the fallbacks are the code paths used on Python 3.10–3.13.
• The RuntimeWarning that FIX intermittent Windows module enumeration failure joblib/threadpoolctl#219 added for dllist failures can no longer be reached on Windows.
• The Windows 3.14 CI jobs no longer exercise dllist.
• The stdlib_dllist() helper in tests/test_threadpoolctl.py still mirrors the 3.7.0 condition, so on Windows 3.14 test_windows_library_path_exceeds_internal_limit is skipped even though the Toolhelp path, which applies the limit, is the one that runs.

Suggested fix

if sys.platform != "emscripten" and (
    sys.platform != "linux"
    # On Linux, dllist is only used on free-threaded 3.15+, where the
    # ctypes.util import no longer creates a CFUNCTYPE callback (#225):
    or sys.version_info[:2] >= (3, 15)
):

If dropping dllist on Windows and macOS was intended, the changelog should say so and stdlib_dllist() should be updated instead.