cpython/Misc/NEWS.d/3.14.0a4.rst

.. date: 2024-12-22-08-54-30
.. gh-issue: 127592
.. nonce: iyuFCC
.. release date: 2025-01-14
.. section: macOS

Usage of the unified Apple System Log APIs was disabled when the minimum
macOS version is earlier than 10.12.

..

.. date: 2025-01-03-23-51-07
.. gh-issue: 128152
.. nonce: IhzElS
.. section: Tools/Demos

Fix a bug where Argument Clinic's C pre-processor parser tried to parse
pre-processor directives inside C comments. Patch by Erlend Aasland.

..

.. date: 2025-01-13-01-29-08
.. gh-issue: 128690
.. nonce: cPFVDb
.. section: Tests

Temporarily do not use test_embed in PGO profile builds until the problem
with test_init_pyvenv_cfg failing in some configurations is resolved.

..

.. date: 2025-01-11-13-40-12
.. gh-issue: 128731
.. nonce: qpKlai
.. section: Library

Fix :exc:`ResourceWarning` in
:meth:`urllib.robotparser.RobotFileParser.read`.

..

.. date: 2025-01-10-15-06-45
.. gh-issue: 71339
.. nonce: EKnpzw
.. section: Library

Add new assertion methods for :mod:`unittest`:
:meth:`~unittest.TestCase.assertHasAttr`,
:meth:`~unittest.TestCase.assertNotHasAttr`,
:meth:`~unittest.TestCase.assertIsSubclass`,
:meth:`~unittest.TestCase.assertNotIsSubclass`
:meth:`~unittest.TestCase.assertStartsWith`,
:meth:`~unittest.TestCase.assertNotStartsWith`,
:meth:`~unittest.TestCase.assertEndsWith` and
:meth:`~unittest.TestCase.assertNotEndsWith`.

..

.. date: 2025-01-10-13-34-33
.. gh-issue: 118761
.. nonce: qRB8nS
.. section: Library

Improve import time of :mod:`pickle` by 25% by removing an unnecessary
regular expression. As such, :mod:`re` is no more implicitly available as
``pickle.re``. Patch by Bénédikt Tran.

..

.. date: 2025-01-09-12-06-52
.. gh-issue: 128661
.. nonce: ixx_0z
.. section: Library

Fixes :func:`typing.evaluate_forward_ref` not showing deprecation when
``type_params`` arg is not passed.

..

.. date: 2025-01-08-03-09-29
.. gh-issue: 128562
.. nonce: Mlv-yO
.. section: Library

Fix possible conflicts in generated :mod:`tkinter` widget names if the
widget class name ends with a digit.

..

.. date: 2025-01-06-21-35-00
.. gh-issue: 128559
.. nonce: 6fxcDM
.. section: Library

Improved import time of :mod:`asyncio`.

..

.. date: 2025-01-06-18-41-08
.. gh-issue: 128552
.. nonce: fV-f8j
.. section: Library

Fix cyclic garbage introduced by :meth:`asyncio.loop.create_task` and
:meth:`asyncio.TaskGroup.create_task` holding a reference to the created
task if it is eager.

..

.. date: 2025-01-05-11-46-14
.. gh-issue: 128340
.. nonce: gKI0uU
.. section: Library

Add internal thread safe handle to be used in
:meth:`asyncio.loop.call_soon_threadsafe` for thread safe cancellation.

..

.. date: 2025-01-04-11-32-46
.. gh-issue: 128182
.. nonce: SJ2Zsa
.. section: Library

Fix crash when using :mod:`ctypes` pointers concurrently on the :term:`free
threaded <free threading>` build.

..

.. date: 2025-01-02-15-20-17
.. gh-issue: 128400
.. nonce: UMiG4f
.. section: Library

Only show the current thread in :mod:`faulthandler` on the :term:`free
threaded <free threading>` build to prevent races.

..

.. date: 2025-01-02-13-05-16
.. gh-issue: 128400
.. nonce: 5N43fF
.. section: Library

Fix crash when using :func:`faulthandler.dump_traceback` while other threads
are active on the :term:`free threaded <free threading>` build.

..

.. date: 2025-01-01-19-24-43
.. gh-issue: 128388
.. nonce: 8UdMz_
.. section: Library

Fix ``PyREPL`` on Windows to support more keybindings, like the
:kbd:`Control-←` and :kbd:`Control-→` word-skipping keybindings and those
with meta (i.e. :kbd:`Alt`), e.g. :kbd:`Alt-d` to ``kill-word`` or
:kbd:`Alt-Backspace` ``backward-kill-word``.

..

.. date: 2024-12-30-20-48-28
.. gh-issue: 88834
.. nonce: RIvgwc
.. section: Library

Unify the instance check for :class:`typing.Union` and
:class:`types.UnionType`: :class:`!Union` now uses the instance checks
against its parameters instead of the subclass checks.

..

.. date: 2024-12-29-13-49-46
.. gh-issue: 128302
.. nonce: psRpPN
.. section: Library

Fix :meth:`!xml.dom.xmlbuilder.DOMEntityResolver.resolveEntity`, which was
broken by the Python 3.0 transition.

..

.. date: 2024-12-29-00-33-34
.. gh-issue: 128317
.. nonce: WgFina
.. section: Library

Highlight today in colour in :mod:`calendar`'s CLI output. Patch by Hugo van
Kemenade.

..

.. date: 2024-12-27-16-28-57
.. gh-issue: 128302
.. nonce: 2GMvyl
.. section: Library

Allow :meth:`!xml.dom.xmlbuilder.DOMParser.parse` to correctly handle
:class:`!xml.dom.xmlbuilder.DOMInputSource` instances that only have a
:attr:`!systemId` attribute set.

..

.. date: 2024-12-21-11-12-50
.. gh-issue: 128151
.. nonce: aq7vpG
.. section: Library

Improve generation of :class:`~uuid.UUID` objects version 3, 4, 5, and 8 via
their dedicated functions by 30%. Patch by Bénédikt Tran.

..

.. date: 2024-12-20-10-57-10
.. gh-issue: 128118
.. nonce: mYak8i
.. section: Library

Improve performance of :func:`copy.copy` by 30% via a fast path for atomic
types and container types.

..

.. date: 2024-12-19-20-46-01
.. gh-issue: 127946
.. nonce: 4lM3Op
.. section: Library

Fix crash when modifying :class:`ctypes._CFuncPtr` objects concurrently on
the :term:`free threaded <free threading>` build.

..

.. date: 2024-12-18-10-18-55
.. gh-issue: 128062
.. nonce: E9oU7-
.. section: Library

Revert the font of :mod:`turtledemo`'s menu bar to its default value and
display the shortcut keys in the correct position.

..

.. date: 2024-12-18-00-07-50
.. gh-issue: 128014
.. nonce: F3aUbz
.. section: Library

Fix resetting the default window icon by passing ``default=''`` to the
:mod:`tkinter` method :meth:`!wm_iconbitmap`.

..

.. date: 2024-12-17-15-23-40
.. gh-issue: 41872
.. nonce: 31LjKY
.. section: Library

Fix quick extraction of module docstrings from a file in :mod:`pydoc`. It
now supports docstrings with single quotes, escape sequences, raw string
literals, and other Python syntax.

..

.. date: 2024-12-17-13-21-52
.. gh-issue: 127060
.. nonce: mv2bX6
.. section: Library

Set TERM environment variable to "dumb" to disable traceback colors in IDLE,
since IDLE doesn't understand ANSI escape sequences. Patch by Victor
Stinner.

..

.. date: 2024-12-17-12-41-07
.. gh-issue: 126742
.. nonce: l07qvT
.. section: Library

Fix support of localized error messages reported by :manpage:`dlerror(3)`
and :manpage:`gdbm_strerror <gdbm(3)>` in :mod:`ctypes` and :mod:`dbm.gnu`
functions respectively. Patch by Bénédikt Tran.

..

.. date: 2024-12-13-14-21-04
.. gh-issue: 122548
.. nonce: hq3Vud
.. section: Library

Adds two new local events to sys.monitoring, ``BRANCH_LEFT`` and
``BRANCH_RIGHT``. This allows the two arms of the branch to be disabled
independently, which should hugely improve performance of branch-level
coverage tools. The old branch event, ``BRANCH`` is now deprecated.

..

.. date: 2024-12-12-07-27-51
.. gh-issue: 127847
.. nonce: ksfNKM
.. section: Library

Fix the position when doing interleaved seeks and reads in uncompressed,
unencrypted zip files returned by :meth:`zipfile.ZipFile.open`.

..

.. date: 2024-12-06-21-03-11
.. gh-issue: 127688
.. nonce: NJqtc-
.. section: Library

Add the :data:`~os.SCHED_DEADLINE` and :data:`~os.SCHED_NORMAL` constants to
the :mod:`os` module.

..

.. date: 2024-12-04-10-39-29
.. gh-issue: 83662
.. nonce: CG1s3m
.. section: Library

Add missing ``__class_getitem__`` method to the Python implementation of
:func:`functools.partial`, to make it compatible with the C version. This is
mainly relevant for alternative Python implementations like PyPy and
GraalPy, because CPython will usually use the C-implementation of that
function.

..

.. date: 2024-12-03-20-28-08
.. gh-issue: 127586
.. nonce: zgotYF
.. section: Library

:class:`multiprocessing.pool.Pool` now properly restores blocked signal
handlers of the parent thread when creating processes via either *spawn* or
*forkserver*.

..

.. date: 2024-12-03-14-45-16
.. gh-issue: 98188
.. nonce: GX9i2b
.. section: Library

Fix an issue in :meth:`email.message.Message.get_payload` where data cannot
be decoded if the Content Transfer Encoding mechanism contains trailing
whitespaces or additional junk text. Patch by Hui Liu.

..

.. date: 2024-12-02-19-13-19
.. gh-issue: 127529
.. nonce: Pj1Xtf
.. section: Library

Correct behavior of
:func:`!asyncio.selector_events.BaseSelectorEventLoop._accept_connection` in
handling :exc:`ConnectionAbortedError` in a loop. This improves performance
on OpenBSD.

..

.. date: 2024-11-28-14-24-12
.. gh-issue: 127360
.. nonce: HVKt-c
.. section: Library

When a descriptive error message cannot be provided for an
:exc:`ssl.SSLError`, the "unknown error" message now shows the internal
error code (as retrieved by ``ERR_get_error`` and similar OpenSSL
functions).

..

.. date: 2024-11-24-14-53-35
.. gh-issue: 127196
.. nonce: 8CBkUa
.. section: Library

Fix crash when dict with keys in invalid encoding were passed to several
functions in ``_interpreters`` module.

..

.. date: 2024-11-19-10-46-57
.. gh-issue: 124130
.. nonce: OZ_vR5
.. section: Library

Fix a bug in matching regular expression ``\B`` in empty input string. Now
it is always the opposite of ``\b``. To get an old behavior, use
``(?!\A\Z)\B``. To get a new behavior in old Python versions, use
``(?!\b)``.

..

.. date: 2024-11-11-07-56-03
.. gh-issue: 126639
.. nonce: AmVSt-
.. section: Library

:class:`tempfile.NamedTemporaryFile` will now issue a :exc:`ResourceWarning`
when it is finalized by the garbage collector without being explicitly
closed.

..

.. date: 2024-11-09-15-59-51
.. gh-issue: 126624
.. nonce: bN53Va
.. section: Library

Expose error code :data:`~xml.parsers.expat.errors.XML_ERROR_NOT_STARTED` of
Expat >=2.6.4 in :mod:`xml.parsers.expat.errors`.

..

.. date: 2024-10-31-14-31-36
.. gh-issue: 126225
.. nonce: vTxGXm
.. section: Library

:mod:`getopt` and :mod:`optparse` are no longer marked as deprecated. There
are legitimate reasons to use one of these modules in preference to
:mod:`argparse`, and none of these modules are at risk of being removed from
the standard library. Of the three, ``argparse`` remains the recommended
default choice, *unless* one of the concerns noted at the top of the
``optparse`` module documentation applies.

..

.. date: 2024-10-04-09-56-45
.. gh-issue: 124761
.. nonce: N4pSD6
.. section: Library

Add :data:`~socket.SO_REUSEPORT_LB` constant to :mod:`socket` for FreeBSD.

..

.. date: 2024-09-04-14-13-14
.. gh-issue: 121720
.. nonce: z9hhXQ
.. section: Library

:class:`enum.EnumDict` can now be used without resorting to private API.

..

.. date: 2024-08-28-16-10-37
.. gh-issue: 123424
.. nonce: u96_i6
.. section: Library

Add :meth:`zipfile.ZipInfo._for_archive` setting default properties on
:class:`~zipfile.ZipInfo` objects. Patch by Bénédikt Tran and Jason R.
Coombs.

..

.. date: 2024-07-13-13-25-31
.. gh-issue: 121676
.. nonce: KDLS11
.. section: Library

Deprecate calling the Python implementation of :meth:`functools.reduce` with
a ``function`` or ``sequence`` as a :term:`keyword argument`. This will be
forbidden in Python 3.16 in order to match the C implementation.

..

.. date: 2023-11-12-21-53-40
.. gh-issue: 112015
.. nonce: 2WPRxE
.. section: Library

:func:`ctypes.memoryview_at` now exists to create a :class:`memoryview`
object that refers to the supplied pointer and length. This works like
:func:`ctypes.string_at` except it avoids a buffer copy, and is typically
useful when implementing pure Python callback functions that are passed
dynamically-sized buffers.

..

.. date: 2022-07-28-12-32-59
.. gh-issue: 95371
.. nonce: F24IFC
.. section: Library

Added support for other image formats (PNG, PGM, and PPM) to the turtle
module. Patch by Shin-myoung-serp.

..

.. date: 2025-01-13-12-48-30
.. gh-issue: 128078
.. nonce: qOsl9B
.. section: Core and Builtins

Fix a :exc:`SystemError` when using :func:`anext` with a default tuple
value. Patch by Bénédikt Tran.

..

.. date: 2025-01-11-12-39-17
.. gh-issue: 128717
.. nonce: i65d06
.. section: Core and Builtins

Fix a crash when setting the recursion limit while other threads are active
on the :term:`free threaded <free threading>` build.

..

.. date: 2025-01-09-11-46-57
.. gh-issue: 124483
.. nonce: KRtBeQ
.. section: Core and Builtins

Treat ``Py_DECREF`` and variants as escaping when generating opcode and uop
metadata. This prevents the possibility of a ``__del__`` method causing the
JIT to behave incorrectly.

..

.. date: 2025-01-07-19-48-56
.. gh-issue: 126703
.. nonce: 0ISs-7
.. section: Core and Builtins

Improve performance of class methods by using a freelist.

..

.. date: 2024-12-24-01-40-12
.. gh-issue: 128137
.. nonce: gsTwr_
.. section: Core and Builtins

Update :c:type:`PyASCIIObject` layout to handle interned field with the
atomic operation. Patch by Donghee Na.

..

.. date: 2024-12-23-11-14-07
.. gh-issue: 128192
.. nonce: 02mEhD
.. section: Library

Upgrade HTTP digest authentication algorithm for :mod:`urllib.request` by
supporting SHA-256 digest authentication as specified in :rfc:`7616`.

..

.. date: 2024-12-22-15-47-44
.. gh-issue: 126868
.. nonce: RpjKez
.. section: Core and Builtins

Increase usage of freelist for :class:`int` allocation.

..

.. date: 2024-12-20-23-07-33
.. gh-issue: 114203
.. nonce: 84NgoW
.. section: Core and Builtins

Optimize ``Py_BEGIN_CRITICAL_SECTION`` for simple recursive calls.

..

.. date: 2024-12-20-12-25-16
.. gh-issue: 127705
.. nonce: WmCz1z
.. section: Core and Builtins

Adds stackref debugging when ``Py_STACKREF_DEBUG`` is set. Finds all
double-closes and leaks, logging the origin and last borrow.

Inspired by HPy's debug mode.
https://docs.hpyproject.org/en/latest/debug-mode.html

..

.. date: 2024-12-18-14-22-48
.. gh-issue: 128079
.. nonce: SUD5le
.. section: Core and Builtins

Fix a bug where :keyword:`except* <except_star>` does not properly check the
return value of an :exc:`ExceptionGroup`'s :meth:`~BaseExceptionGroup.split`
function, leading to a crash in some cases. Now when
:meth:`~BaseExceptionGroup.split` returns an invalid object,
:keyword:`except* <except_star>` raises a :exc:`TypeError` with the original
raised :exc:`ExceptionGroup` object chained to it.

..

.. date: 2024-12-17-22-28-15
.. gh-issue: 128030
.. nonce: H1ptOD
.. section: Core and Builtins

Avoid error from calling ``PyModule_GetFilenameObject`` on a non-module
object when importing a non-existent symbol from a non-module object.

..

.. date: 2024-12-17-18-20-37
.. gh-issue: 128035
.. nonce: JwqHdB
.. section: Library

Indicate through :data:`ssl.HAS_PHA` whether the :mod:`ssl` module supports
TLSv1.3 post-handshake client authentication (PHA). Patch by Will
Childs-Klein.

..

.. date: 2024-12-17-13-45-33
.. gh-issue: 127274
.. nonce: deNxNC
.. section: Core and Builtins

Add a new flag, ``CO_METHOD``, to :attr:`~codeobject.co_flags` that
indicates whether the code object belongs to a function defined in class
scope.

..

.. date: 2024-12-15-21-11-26
.. gh-issue: 66409
.. nonce: wv109z
.. section: Core and Builtins

During the :ref:`path initialization <sys-path-init>`, we now check if
``base_exec_prefix`` is the same as ``base_prefix`` before falling back to
searching the Python interpreter directory.

..

.. date: 2024-12-15-19-51-54
.. gh-issue: 127970
.. nonce: vdUp-y
.. section: Core and Builtins

We now use the location of the ``libpython`` runtime library used in the
current process to determine :data:`sys.base_prefix` on all platforms
implementing the `dladdr
<https://pubs.opengroup.org/onlinepubs/9799919799/functions/dladdr.html>`_
function defined by the UNIX standard — this includes Linux, Android, macOS,
iOS, FreeBSD, etc. This was already the case on Windows and macOS Framework
builds.

..

.. date: 2024-12-13-15-21-45
.. gh-issue: 127773
.. nonce: E-DZR4
.. section: Core and Builtins

Do not use the type attribute cache for types with incompatible :term:`MRO`.

..

.. date: 2024-12-13-14-17-24
.. gh-issue: 127903
.. nonce: vemHSl
.. section: Core and Builtins

``Objects/unicodeobject.c``: fix a crash on DEBUG builds in
``_copy_characters`` when there is nothing to copy.

..

.. date: 2024-12-11-14-32-22
.. gh-issue: 127809
.. nonce: 0W8khe
.. section: Core and Builtins

Fix an issue where the experimental JIT may infer an incorrect result type
for exponentiation (``**`` and ``**=``), leading to bugs or crashes.

..

.. date: 2024-12-02-18-15-37
.. gh-issue: 126862
.. nonce: fdIK7T
.. section: Core and Builtins

Fix a possible overflow when a class inherits from an absurd number of
super-classes. Reported by Valery Fedorenko. Patch by Bénédikt Tran.

..

.. date: 2025-01-12-12-19-51
.. gh-issue: 128400
.. nonce: OwoIDw
.. section: C API

:c:func:`Py_FatalError` no longer shows all threads on the :term:`free
threaded <free threading>` build to prevent crashes.

..

.. date: 2025-01-08-13-13-18
.. gh-issue: 128629
.. nonce: gSmzyl
.. section: C API

Add macros :c:func:`Py_PACK_VERSION` and :c:func:`Py_PACK_FULL_VERSION` for
bit-packing Python version numbers.

..

.. date: 2024-12-16-21-59-06
.. gh-issue: 128008
.. nonce: fa9Jt0
.. section: C API

Add :c:func:`PyWeakref_IsDead` function, which tests if a weak reference is
dead.

..

.. date: 2024-12-11-13-01-26
.. gh-issue: 127350
.. nonce: uEBZZ4
.. section: C API

Add :c:func:`Py_fopen` function to open a file. Similar to the
:c:func:`!fopen` function, but the *path* parameter is a Python object and
an exception is set on error. Add also :c:func:`Py_fclose` function to close
a file, function needed for Windows support. Patch by Victor Stinner.

..

.. date: 2025-01-09-19-44-00
.. gh-issue: 128627
.. nonce: mHzsEd
.. section: Build

For Emscripten builds the function pointer cast call trampoline now uses the
wasm-gc ref.test instruction if it's available instead of Wasm JS type
reflection.

..

.. date: 2025-01-04-22-39-10
.. gh-issue: 128472
.. nonce: Wt5E6M
.. section: Build

Skip BOLT optimization of functions using computed gotos, fixing errors on
build with LLVM 19.

..

.. date: 2025-01-02-12-50-46
.. gh-issue: 115765
.. nonce: jko7Fg
.. section: Build

GNU Autoconf 2.72 is now required to generate :file:`configure`. Patch by
Erlend Aasland.

..

.. date: 2025-01-02-11-02-45
.. gh-issue: 123925
.. nonce: TLlyUi
.. section: Build

Fix building the :mod:`curses` module on platforms with libncurses but
without libncursesw.

..

.. date: 2024-12-31-17-09-37
.. gh-issue: 90905
.. nonce: PjLNai
.. section: Build

Add support for cross-compiling to x86_64 on aarch64/arm64 macOS.

..

.. date: 2024-12-28-21-05-19
.. gh-issue: 128321
.. nonce: 0UvbXw
.. section: Build

Set ``LIBS`` instead of ``LDFLAGS`` when checking if :mod:`sqlite3` library
functions are available. This fixes the ordering of linked libraries during
checks, which was incorrect when using a statically linked ``libsqlite3``.

..

.. date: 2024-12-21-09-56-37
.. gh-issue: 100384
.. nonce: Ib-XrN
.. section: Build

Error on ``unguarded-availability`` in macOS builds, preventing invalid use
of symbols that are not available in older versions of the OS.

..

.. date: 2024-12-20-09-03-22
.. gh-issue: 128104
.. nonce: m_SoVx
.. section: Build

Remove ``Py_STRFTIME_C99_SUPPORT`` conditions in favor of requiring C99
:manpage:`strftime(3)` specifier support at build time. When
cross-compiling, there is no build time check and support is assumed.

..

.. date: 2024-12-16-16-16-35
.. gh-issue: 127951
.. nonce: lpE13-
.. section: Build

Add option ``--pystats`` to the Windows build to enable performance
statistics collection.