.. bpo: 45716

.. date: 2021-11-04-20-19-07

.. nonce: 5C0pA1

.. release date: 2021-11-05

.. section: Core and Builtins

Improve the :exc:`SyntaxError` message when using ``True``, ``None`` or

``False`` as keywords in a function call. Patch by Pablo Galindo.

..

.. bpo: 45688

.. date: 2021-11-02-09-27-46

.. nonce: v5Der1

.. section: Core and Builtins

:data:`sys.stdlib_module_names` now contains the macOS-specific module

..

.. bpo: 45379

.. date: 2021-10-23-13-49-00

.. nonce: ZF7G3n

.. section: Core and Builtins

Clarify :exc:`ImportError` message when we try to explicitly import a frozen

module but frozen modules are disabled.

..

.. bpo: 44525

.. date: 2021-10-20-11-57-31

.. nonce: veL4lJ

.. section: Core and Builtins

closure)

..

.. bpo: 45530

.. date: 2021-10-20-01-28-26

.. nonce: 5r7n4m

.. section: Core and Builtins

Cases of sorting using tuples as keys may now be significantly faster in

some cases. Patch by Tim Peters.

The order of the result may differ from earlier releases if the tuple

elements don't define a total ordering (see

:ref:`expressions-value-comparisons` for information on total ordering).

It's generally true that the result of sorting simply isn't well-defined in

the absence of a total ordering on list elements.

..

.. bpo: 45526

.. date: 2021-10-19-10-29-47

.. nonce: WQnvW9

.. section: Core and Builtins

In obmalloc, set ADDRESS_BITS to not ignore any bits (ignored 16 before).

That is safer in the case that the kernel gives user-space virtual addresses

that span a range greater than 48 bits.

..

.. bpo: 30570

.. date: 2021-10-19-01-04-08

.. nonce: _G30Ms

.. section: Core and Builtins

Fixed a crash in ``issubclass()`` from infinite recursion when searching

pathological ``__bases__`` tuples.

..

.. bpo: 45521

.. date: 2021-10-18-22-40-33

.. nonce: GdMiuW

.. section: Core and Builtins

Fix a bug in the obmalloc radix tree code. On 64-bit machines, the bug

causes the tree to hold 46-bits of virtual addresses, rather than the

intended 48-bits.

..

.. bpo: 45494

.. date: 2021-10-16-17-27-48

.. nonce: vMt1g4

.. section: Core and Builtins

Fix parser crash when reporting errors involving invalid continuation

characters. Patch by Pablo Galindo.

..

.. bpo: 45445

.. date: 2021-10-12-14-41-39

.. nonce: _F5cMf

.. section: Core and Builtins

Python now fails to initialize if it finds an invalid :option:`-X` option in

the command line. Patch by Pablo Galindo.

..

.. bpo: 45340

.. date: 2021-10-08-09-47-38

.. nonce: ukHgDb

.. section: Core and Builtins

Object attributes are held in an array instead of a dictionary. An object's

dictionary are created lazily, only when needed. Reduces the memory

consumption of a typical Python object by about 30%. Patch by Mark Shannon.

..

.. bpo: 45408

.. date: 2021-10-07-21-26-44

.. nonce: qUqzcd

.. section: Core and Builtins

Fix a crash in the parser when reporting tokenizer errors that occur at the

same time unclosed parentheses are detected. Patch by Pablo Galindo.

..

.. bpo: 29410

.. date: 2021-10-07-19-09-12

.. nonce: bg5SYp

.. section: Core and Builtins

Add SipHash13 for string hash algorithm and use it by default.

..

.. bpo: 45385

.. date: 2021-10-06-21-20-11

.. nonce: CTUT8s

.. section: Core and Builtins

..

.. bpo: 45367

.. date: 2021-10-05-03-49-07

.. nonce: _astoU

.. section: Core and Builtins

Specialized the ``BINARY_MULTIPLY`` opcode to ``BINARY_MULTIPLY_INT`` and

``BINARY_MULTIPLY_FLOAT`` using the PEP 659 machinery.

..

.. bpo: 21736

.. date: 2021-10-01-09-21-02

.. nonce: RI47BU

.. section: Core and Builtins

Frozen stdlib modules now have ``__file__`` to the .py file they would

otherwise be loaded from, if possible. For packages, ``__path__`` now has

the correct entry instead of being an empty list, which allows unfrozen

submodules to be imported. These are set only if the stdlib directory is

known when the runtime is initialized. Note that the file at ``__file__``

is not guaranteed to exist. None of this affects non-stdlib frozen modules

nor, for now, frozen modules imported using

``PyImport_ImportFrozenModule()``. Also, at the moment ``co_filename`` is

not updated for the module.

..

.. bpo: 45020

.. date: 2021-10-01-09-06-54

.. nonce: Cj5VQN

.. section: Core and Builtins

For frozen stdlib modules, record the original module name as

``module.__spec__.loader_state.origname``. If the value is different than

``module.__spec__.name`` then the module was defined as an alias in

Tools/scripts/freeze_modules.py. If it is ``None`` then the module comes

from a source file outside the stdlib.

..

.. bpo: 45324

.. date: 2021-09-29-12-02-39

.. nonce: BTQElX

.. section: Core and Builtins

In FrozenImporter.find_spec(), we now preserve the information needed in

exec_module() to load the module. This change mostly impacts internal

details, rather than changing the importer's behavior.

..

.. bpo: 45292

.. date: 2021-09-26-18-18-50

.. nonce: aX5HVr

.. section: Core and Builtins

Implement :pep:`654`. Add :class:`ExceptionGroup` and

:class:`BaseExceptionGroup`. Update traceback display code.

..

.. bpo: 40116

.. date: 2021-09-23-14-00-05

.. nonce: KaoeFs

.. section: Core and Builtins

Change to the implementation of split dictionaries. Classes where the

instances differ either in the exact set of attributes, or in the order in

which those attributes are set, can still share keys. This should have no

observable effect on users of Python or the C-API. Patch by Mark Shannon.

..

.. bpo: 44050

.. date: 2021-09-08-00-30-09

.. nonce: mFI15u

.. section: Core and Builtins

Extensions that indicate they use global state (by setting ``m_size`` to -1)

can again be used in multiple interpreters. This reverts to behavior of

Python 3.8.

..

.. bpo: 44525

.. date: 2021-06-28-22-23-59

.. nonce: sSvUKG

.. section: Core and Builtins

Setup initial specialization infrastructure for the ``CALL_FUNCTION``

opcode. Implemented initial specializations for C function calls:

* ``CALL_FUNCTION_BUILTIN_O`` for ``METH_O`` flag.

* ``CALL_FUNCTION_BUILTIN_FAST`` for ``METH_FASTCALL`` flag without keywords.

* ``CALL_FUNCTION_LEN`` for ``len(o)``.

* ``CALL_FUNCTION_ISINSTANCE`` for ``isinstance(o, t)``.

..

.. bpo: 44511

.. date: 2021-06-26-16-55-08

.. nonce: k8sMvV

.. section: Core and Builtins

Improve the generated bytecode for class and mapping patterns.

..

.. bpo: 43706

.. date: 2021-04-03-02-44-15

.. nonce: jjsXlT

.. section: Core and Builtins

Speed up calls to ``enumerate()`` by using the :pep:`590` ``vectorcall``

..

.. bpo: 45679

.. date: 2021-10-30-21-11-37

.. nonce: Dq8Cpu

.. section: Library

Fix caching of multi-value :data:`typing.Literal`. ``Literal[True, 2]`` is

no longer equal to ``Literal[1, 2]``.

..

.. bpo: 42064

.. date: 2021-10-27-13-28-52

.. nonce: UK4jgV

.. section: Library

Convert :mod:`sqlite3` to multi-phase initialisation (PEP 489). Patches by

Erlend E. Aasland.

..

.. bpo: 45438

.. date: 2021-10-27-10-05-39

.. nonce: Xz5lGU

.. section: Library

Fix typing.Signature string representation for generic builtin types.

..

.. bpo: 45613

.. date: 2021-10-26-14-29-54

.. nonce: 55Ie3c

.. section: Library

:mod:`sqlite3` now sets :attr:`sqlite3.threadsafety` based on the default

threading mode the underlying SQLite library has been compiled with. Patch

by Erlend E. Aasland.

..

.. bpo: 45574

.. date: 2021-10-22-23-06-33

.. nonce: svqA84

.. section: Library

Fix warning about ``print_escape`` being unused.

..

.. bpo: 45581

.. date: 2021-10-22-21-57-02

.. nonce: rlH6ay

.. section: Library

:meth:`sqlite3.connect` now correctly raises :exc:`MemoryError` if the

underlying SQLite API signals memory error. Patch by Erlend E. Aasland.

..

.. bpo: 45557

.. date: 2021-10-21-16-18-51

.. nonce: 4MQt4r

.. section: Library

:func:`pprint.pprint` now handles *underscore_numbers* correctly.

Previously it was always setting it to ``False``.

..

.. bpo: 44019

.. date: 2021-10-21-10-14-22

.. nonce: Xk4Ncr

.. section: Library

Add :func:`operator.call` to ``operator.__all__``. Patch by Kreusada.

..

.. bpo: 42174

.. date: 2021-10-19-01-30-57

.. nonce: O2w9bi

.. section: Library

:meth:`shutil.get_terminal_size` now falls back to sane values if the column

or line count are 0.

..

.. bpo: 35673

.. date: 2021-10-18-18-12-47

.. nonce: KOkHWe

.. section: Library

Improve the introspectability of the ``__loader__`` attribute for namespace

packages. :class:`importlib.machinery.NamespaceLoader` is now public, and

implements the :class:`importlib.abc.InspectLoader` interface.

``_NamespaceLoader`` is kept for backward compatibility.

..

.. bpo: 45515

.. date: 2021-10-18-14-52-48

.. nonce: aXdvm_

.. section: Library

Add references to :mod:`zoneinfo` in the :mod:`datetime` documentation,

mostly replacing outdated references to ``dateutil.tz``. Change by Paul

Ganssle.

..

.. bpo: 45475

.. date: 2021-10-18-10-46-47

.. nonce: sb9KDF

.. section: Library

Reverted optimization of iterating :class:`gzip.GzipFile`,

:class:`bz2.BZ2File`, and :class:`lzma.LZMAFile` (see bpo-43787) because it

caused regression when user iterate them without having reference of them.

Patch by Inada Naoki.

..

.. bpo: 45489

.. date: 2021-10-16-23-46-39

.. nonce: QB0rhG

.. section: Library

Update :class:`~typing.ForwardRef` to support ``|`` operator. Patch by

..

.. bpo: 42222

.. date: 2021-10-15-11-30-11

.. nonce: hdHyac

.. section: Library

Removed deprecated support for float arguments in *randrange()*.

..

.. bpo: 45428

.. date: 2021-10-14-18-04-17

.. nonce: mM2War

.. section: Library

Fix a regression in py_compile when reading filenames from standard input.

..

.. bpo: 45467

.. date: 2021-10-14-13-31-19

.. nonce: Q7Ma6A

.. section: Library

Fix incremental decoder and stream reader in the "raw-unicode-escape" codec.

Previously they failed if the escape sequence was split.

..

.. bpo: 45461

.. date: 2021-10-14-00-19-02

.. nonce: 4LB_tJ

.. section: Library

Fix incremental decoder and stream reader in the "unicode-escape" codec.

Previously they failed if the escape sequence was split.

..

.. bpo: 45239

.. date: 2021-10-13-17-52-48

.. nonce: 7li1_0

.. section: Library

Fixed :func:`email.utils.parsedate_tz` crashing with

:exc:`UnboundLocalError` on certain invalid input instead of returning

``None``. Patch by Ben Hoyt.

..

.. bpo: 45417

.. date: 2021-10-12-20-35-06

.. nonce: gQM-O7

.. section: Library

Fix quadratic behaviour in the enum module: Creation of enum classes with a

lot of entries was quadratic.

..

.. bpo: 45249

.. date: 2021-10-10-16-14-33

.. nonce: xqLliz

.. section: Library

Fix the behaviour of :func:`traceback.print_exc` when displaying the caret

when the ``end_offset`` in the exception is set to 0. Patch by Pablo Galindo

..

.. bpo: 45416

.. date: 2021-10-10-09-42-34

.. nonce: n35O0_

.. section: Library

Fix use of :class:`asyncio.Condition` with explicit :class:`asyncio.Lock`

objects, which was a regression due to removal of explicit loop arguments.

Patch by Joongi Kim.

..

.. bpo: 20028

.. date: 2021-10-10-00-25-36

.. nonce: bPx4Z8

.. section: Library

Empty escapechar/quotechar is not allowed when initializing

..

.. bpo: 44904

.. date: 2021-10-09-18-42-27

.. nonce: RlW5h8

.. section: Library

Fix bug in the :mod:`doctest` module that caused it to fail if a docstring

included an example with a ``classmethod`` ``property``. Patch by Alex

Waygood.

..

.. bpo: 45406

.. date: 2021-10-08-19-24-48

.. nonce: Qh_Mz4

.. section: Library

Make :func:`inspect.getmodule` catch ``FileNotFoundError`` raised by

could not be determined.

..

.. bpo: 45411

.. date: 2021-10-08-11-29-29

.. nonce: 4jR--U

.. section: Library

Add extensions for files containing subtitles - .srt & .vtt - to the

mimetypes.py module.

..

.. bpo: 10716

.. date: 2021-10-08-04-11-55

.. nonce: QSRVK2

.. section: Library

Migrated pydoc to HTML5 (without changing the look of it). Side effect is to

update xmlrpc's ``ServerHTMLDoc`` which now uses the CSS too. cgitb now

relies less on pydoc (as it can't use the CSS file).

..

.. bpo: 27580

.. date: 2021-10-07-21-11-48

.. nonce: tGcBTH

.. section: Library

Add support of null characters in :mod:`csv`.

..

.. bpo: 45262

.. date: 2021-10-07-14-04-10

.. nonce: HqF71Z

.. section: Library

Prevent use-after-free in asyncio. Make sure the cached running loop holder

gets cleared on dealloc to prevent use-after-free in get_running_loop

..

.. bpo: 45386

.. date: 2021-10-07-00-05-05

.. nonce: q9ORpA

.. section: Library

Make :mod:`xmlrpc.client` more robust to C runtimes where the underlying C

``strftime`` function results in a ``ValueError`` when testing for year

formatting options.

..

.. bpo: 20028

.. date: 2021-10-03-21-14-37

.. nonce: zBA4RK

.. section: Library

Improve error message of :class:`csv.Dialect` when initializing. Patch by

..

.. bpo: 45343

.. date: 2021-10-01-23-07-02

.. nonce: ixmctD

.. section: Library

Update bundled pip to 21.2.4 and setuptools to 58.1.0

..

.. bpo: 45328

.. date: 2021-09-30-08-22-44

.. nonce: 8Z-Q0B

.. section: Library

Fixed :class:`http.client.HTTPConnection` to work properly in OSs that don't

support the ``TCP_NODELAY`` socket option.

..

.. bpo: 45243

.. date: 2021-09-20-01-25-09

.. nonce: 0pJf0U

.. section: Library

Add :meth:`~sqlite3.Connection.setlimit` and

:meth:`~sqlite3.Connection.getlimit` to :class:`sqlite3.Connection` for

setting and getting SQLite limits by connection basis. Patch by Erlend E.

Aasland.

..

.. bpo: 45320

.. date: 2021-09-15-10-21-10

.. nonce: 4qaf5x

.. section: Library

Removed from the :mod:`inspect` module:

* the ``getargspec`` function, deprecated since Python 3.0;

use :func:`inspect.signature` or :func:`inspect.getfullargspec` instead.

* the ``formatargspec`` function, deprecated since Python 3.5;

use the :func:`inspect.signature` function and :class:`Signature` object

directly.

functions, deprecated since Python 3.5; use the

:meth:`Signature.from_callable() <inspect.Signature.from_callable>` method

instead.

Patch by Hugo van Kemenade.

..

.. bpo: 45192

.. date: 2021-09-14-15-52-47

.. nonce: DjA-BI

.. section: Library

Fix the ``tempfile._infer_return_type`` function so that the ``dir``

argument of the :mod:`tempfile` functions accepts an object implementing the

``os.PathLike`` protocol.

Patch by Kyungmin Lee.

..

.. bpo: 45160

.. date: 2021-09-11-14-47-05

.. nonce: VzMXbW

.. section: Library

When tracing a tkinter variable used by a ttk OptionMenu, callbacks are no

longer made twice.

..

.. bpo: 25625

.. date: 2021-09-10-12-53-28

.. nonce: SzcBCw

.. section: Library

Added non parallel-safe :func:`~contextlib.chdir` context manager to change

the current working directory and then restore it on exit. Simple wrapper

around :func:`~os.chdir`.

..

.. bpo: 24139

.. date: 2021-08-30-23-10-48

.. nonce: e38czf

.. section: Library

Add support for SQLite extended result codes in :exc:`sqlite3.Error`. Patch

by Erlend E. Aasland.

..

.. bpo: 24444

.. date: 2021-08-30-00-19-23

.. nonce: Ki4bgz

.. section: Library

Fixed an error raised in :mod:`argparse` help display when help for an

option is set to 1+ blank spaces or when *choices* arg is an empty

container.

..

.. bpo: 44547

.. date: 2021-08-20-10-52-40

.. nonce: eu0iJq

.. section: Library

Implement ``Fraction.__int__``, so that a :class:`fractions.Fraction`

instance ``f`` passes an ``isinstance(f, typing.SupportsInt)`` check.

..

.. bpo: 40321

.. date: 2021-07-22-21-25-56

.. nonce: gBlFmw

.. section: Library

Adds support for HTTP 308 redirects to :mod:`urllib`. See :rfc:`7538` for

details. Patch by Jochem Schulenklopper.

..

.. bpo: 41374

.. date: 2020-07-27-19-21-05

.. nonce: cd-kFL

.. section: Library

Ensure that ``socket.TCP_*`` constants are exposed on Cygwin 3.1.6 and

greater.

..

.. bpo: 35970

.. date: 2019-02-11-19-06-10

.. nonce: ZRvh51

.. section: Library

Add help flag to the base64 module's command line interface. Patch

contributed by Robert Kuska.

..

.. bpo: 45726

.. date: 2021-11-05-12-15-24

.. nonce: GwRr7e

.. section: Documentation

Improve documentation for :func:`functools.singledispatch` and

:class:`functools.singledispatchmethod`.

..

.. bpo: 45680

.. date: 2021-11-03-14-51-03

.. nonce: 9_NTFU

.. section: Documentation

Amend the docs on ``GenericAlias`` objects to clarify that non-container

classes can also implement ``__class_getitem__``. Patch contributed by Alex

Waygood.

..

.. bpo: 45618

.. date: 2021-10-31-20-35-06

.. nonce: RTcNXF

.. section: Documentation

Update Sphinx version used to build the documentation to 4.2.0. Patch by

Maciej Olko.

..

.. bpo: 45655

.. date: 2021-10-28-19-22-55

.. nonce: aPYGaS

.. section: Documentation

Add a new "relevant PEPs" section to the top of the documentation for the

``typing`` module. Patch by Alex Waygood.

..

.. bpo: 45604

.. date: 2021-10-26-10-00-45

.. nonce: Dm-YhV

.. section: Documentation

Add ``level`` argument to ``multiprocessing.log_to_stderr`` function docs.

..

.. bpo: 45516

.. date: 2021-10-22-21-57-42

.. nonce: 7_RMEX

.. section: Documentation

Add protocol description to the :class:`importlib.abc.TraversableResources`

documentation.

..

.. bpo: 45464

.. date: 2021-10-20-16-26-53

.. nonce: mOISBs

.. section: Documentation

Mention in the documentation of :ref:`Built-in Exceptions

<bltin-exceptions>` that inheriting from multiple exception types in a

single subclass is not recommended due to possible memory layout

incompatibility.

..

.. bpo: 45449

.. date: 2021-10-19-01-41-40

.. nonce: fjHZJc

.. section: Documentation

Add note about :pep:`585` in :mod:`collections.abc`.

..

.. bpo: 45516

.. date: 2021-10-18-20-12-18

.. nonce: EJh4K8

.. section: Documentation

Add protocol description to the :class:`importlib.abc.Traversable`

documentation.

..

.. bpo: 20692

.. date: 2021-10-13-00-42-54

.. nonce: K5rGtP

.. section: Documentation

Add Programming FAQ entry explaining that int literal attribute access

requires either a space after or parentheses around the literal.

..

.. bpo: 45678

.. date: 2021-11-04-20-03-32

.. nonce: 1xNMjN

.. section: Tests

Add tests for scenarios in which :class:`functools.singledispatchmethod` is

stacked on top of a method that has already been wrapped by two other

decorators. Patch by Alex Waygood.

..

.. bpo: 45578

.. date: 2021-10-30-19-00-25

.. nonce: bvu6X2

.. section: Tests

Add tests for :func:`dis.distb`

..

.. bpo: 45678

.. date: 2021-10-30-13-12-20

.. nonce: bKrYeS

.. section: Tests

Add tests to ensure that ``functools.singledispatchmethod`` correctly wraps

the attributes of the target function.

..

.. bpo: 45668

.. date: 2021-10-29-17-18-56

.. nonce: MfAw4i

.. section: Tests

PGO tests now pass when Python is built without test extension modules.

..

.. bpo: 45577

.. date: 2021-10-22-19-44-13

.. nonce: dSaNvK

.. section: Tests

Add subtests for all ``pickle`` protocols in ``test_zoneinfo``.

..

.. bpo: 45566

.. date: 2021-10-22-12-05-21

.. nonce: 2gQ3ZB

.. section: Tests

Fix ``test_frozen_pickle`` in ``test_dataclasses`` to check all ``pickle``

versions.

..

.. bpo: 43592

.. date: 2021-10-21-17-22-26

.. nonce: kHRsra

.. section: Tests

:mod:`test.libregrtest` now raises the soft resource limit for the maximum

number of file descriptors when the default is too low for our test suite as

was often the case on macOS.

..

.. bpo: 39679

.. date: 2021-10-18-16-18-41

.. nonce: F18qcE

.. section: Tests

Add more test cases for ``@functools.singledispatchmethod`` when combined with

``@classmethod`` or ``@staticmethod``.

..

.. bpo: 45410

.. date: 2021-10-08-14-03-20

.. nonce: Ex9xe2

.. section: Tests

When libregrtest spawns a worker process, stderr is now written into stdout

to keep messages order. Use a single pipe for stdout and stderr, rather than

two pipes. Previously, messages were out of order which made analysis of

buildbot logs harder Patch by Victor Stinner.

..

.. bpo: 45402

.. date: 2021-10-07-13-43-01

.. nonce: jlQvep

.. section: Tests

Fix test_tools.test_sundry() when Python is built out of tree: fix how the

freeze_modules.py tool locates the _freeze_module program. Patch by Victor

Stinner.

..

.. bpo: 45403

.. date: 2021-10-07-13-27-12

.. nonce: 7QiDvw

.. section: Tests

Fix test_sys.test_stdlib_dir() when Python is built outside the source tree:

compare normalized paths. Patch by Victor Stinner.

..

.. bpo: 45400

.. date: 2021-10-07-13-11-45

.. nonce: h3iT7V

.. section: Tests

Fix test_name_error_suggestions_do_not_trigger_for_too_many_locals() of

test_exceptions if a directory name contains "a1" (like "Python-3.11.0a1"):

use a stricter regular expression. Patch by Victor Stinner.

..

.. bpo: 10572

.. date: 2021-01-07-01-25-38

.. nonce: gEEZ9z

.. section: Tests

Rename :mod:`sqlite3` tests from ``test_sqlite`` to ``test_sqlite3``, and

relocate them to ``Lib/test/test_sqlite3``. Patch by Erlend E. Aasland.

..

.. bpo: 43158

.. date: 2021-11-01-12-51-46

.. nonce: fghS6w

.. section: Build

``setup.py`` now uses values from configure script to build the ``_uuid``

extension module. Configure now detects util-linux's ``libuuid``, too.

..

.. bpo: 45666

.. date: 2021-10-29-12-54-53

.. nonce: w2G63u

.. section: Build

Fix warning of ``swprintf`` and ``%s`` usage in ``_testembed.c``

..

.. bpo: 45548

.. date: 2021-10-28-14-47-22

.. nonce: mdCBxB

.. section: Build

``Modules/Setup`` and ``Modules/makesetup`` have been improved. The

``Setup`` file now contains working rules for all extensions. Outdated

comments have been removed. Rules defined by ``makesetup`` track

dependencies correctly.

..

.. bpo: 45548

.. date: 2021-10-24-21-49-49

.. nonce: UWx0UC

.. section: Build

The :mod:`math` and :mod:`cmath` implementation now require a C99 compatible

``libm`` and no longer ship with workarounds for missing acosh, asinh,

atanh, expm1, and log1p functions.

..