.. bpo: 43434
.. date: 2021-05-02-17-50-23
.. nonce: cy7xz6
.. release date: 2021-05-03
.. section: Security

Creating :class:`sqlite3.Connection` objects now also produces
``sqlite3.connect`` and ``sqlite3.connect/handle`` :ref:`auditing events
<auditing>`. Previously these events were only produced by
:func:`sqlite3.connect` calls. Patch by Erlend E. Aasland.

..

.. bpo: 43998
.. date: 2021-05-01-13-13-40
.. nonce: xhmWD7
.. section: Security

The :mod:`ssl` module sets more secure cipher suites defaults. Ciphers
without forward secrecy and with SHA-1 MAC are disabled by default. Security
level 2 prohibits weak RSA, DH, and ECC keys with less than 112 bits of
security. :class:`~ssl.SSLContext` defaults to minimum protocol version TLS
1.2. Settings are based on Hynek Schlawack's research.

..

.. bpo: 43882
.. date: 2021-04-25-07-46-37
.. nonce: Jpwx85
.. section: Security

The presence of newline or tab characters in parts of a URL could allow some
forms of attacks.

Following the controlling specification for URLs defined by WHATWG
:func:`urllib.parse` now removes ASCII newlines and tabs from URLs,
preventing such attacks.

..

.. bpo: 43472
.. date: 2021-04-21-22-53-31
.. nonce: gjLBTb
.. section: Security

Ensures interpreter-level audit hooks receive the
``cpython.PyInterpreterState_New`` event when called through the
``_xxsubinterpreters`` module.

..

.. bpo: 43362
.. date: 2021-04-18-00-56-44
.. nonce: __5aiP
.. section: Security

Fix invalid free in _sha3 module. The issue was introduced in 3.10.0a1.
Python 3.9 and earlier are not affected.

..

.. bpo: 43762
.. date: 2021-04-07-12-57-41
.. nonce: 7lMtpT
.. section: Security

Add audit events for :func:`sqlite3.connect/handle`,
:meth:`sqlite3.Connection.enable_load_extension`, and
:meth:`sqlite3.Connection.load_extension`. Patch by Erlend E. Aasland.

..

.. bpo: 43756
.. date: 2021-04-06-18-07-48
.. nonce: DLBNqQ
.. section: Security

Add new audit event ``glob.glob/2`` to incorporate the new *root_dir* and
*dir_fd* arguments added to :func:`glob.glob` and :func:`glob.iglob`.

..

.. bpo: 36384
.. date: 2021-03-30-16-29-51
.. nonce: sCAmLs
.. section: Security

:mod:`ipaddress` module no longer accepts any leading zeros in IPv4 address
strings. Leading zeros are ambiguous and interpreted as octal notation by
some libraries. For example the legacy function :func:`socket.inet_aton`
treats leading zeros as octal notation. glibc implementation of modern
:func:`~socket.inet_pton` does not accept any leading zeros. For a while the
:mod:`ipaddress` module used to accept ambiguous leading zeros.

..

.. bpo: 43075
.. date: 2021-01-31-05-28-14
.. nonce: DoAXqO
.. section: Security

Fix Regular Expression Denial of Service (ReDoS) vulnerability in
:class:`urllib.request.AbstractBasicAuthHandler`.  The ReDoS-vulnerable
regex has quadratic worst-case complexity and it allows cause a denial of
service when identifying crafted invalid RFCs. This ReDoS issue is on the
client side and needs remote attackers to control the HTTP server.

..

.. bpo: 42800
.. date: 2021-01-09-17-07-36
.. nonce: _dtZvW
.. section: Security

Audit hooks are now fired for frame.f_code, traceback.tb_frame, and
generator code/frame attribute access.

..

.. bpo: 37363
.. date: 2020-07-04-22-14-46
.. nonce: NDjHNw
.. section: Security

Add audit events to the :mod:`http.client` module.

..

.. bpo: 43977
.. date: 2021-05-02-11-59-00
.. nonce: R0hSDo
.. section: Core and Builtins

Prevent classes being both a sequence and a mapping when pattern matching.

..

.. bpo: 43977
.. date: 2021-04-29-17-40-25
.. nonce: FrQhge
.. section: Core and Builtins

Use :c:member:`~PyTypeObject.tp_flags` on the class object to determine if
the subject is a sequence or mapping when pattern matching. Avoids the need
to import :mod:`collections.abc` when pattern matching.

..

.. bpo: 43892
.. date: 2021-04-29-16-00-28
.. nonce: WXIehI
.. section: Core and Builtins

Restore proper validation of complex literal value patterns when parsing
:keyword:`!match` blocks.

..

.. bpo: 43933
.. date: 2021-04-29-13-49-57
.. nonce: TueFdQ
.. section: Core and Builtins

Set frame.f_lineno to the line number of the 'with' kweyword when executing
the call to ``__exit__``.

..

.. bpo: 43933
.. date: 2021-04-29-13-11-44
.. nonce: mvoV6O
.. section: Core and Builtins

If the current position in a frame has no line number then set the f_lineno
attribute to None, instead of -1, to conform to PEP 626. This should not
normally be possible, but might occur in some unusual circumstances.

..

.. bpo: 43963
.. date: 2021-04-28-01-23-38
.. nonce: u5Y6bS
.. section: Core and Builtins

Importing the :mod:`!_signal` module in a subinterpreter has no longer side
effects.

..

.. bpo: 42739
.. date: 2021-04-27-10-59-10
.. nonce: PrVkKM
.. section: Core and Builtins

The internal representation of line number tables is changed to not use
sentinels, and an explicit length parameter is added to the out of process
API function ``PyLineTable_InitAddressRange``. This makes the handling of
line number tables more robust in some circumstances.

..

.. bpo: 43908
.. date: 2021-04-26-21-20-41
.. nonce: 2L51nO
.. section: Library

Make :mod:`re` types immutable. Patch by Erlend E. Aasland.

..

.. bpo: 43908
.. date: 2021-04-26-20-59-17
.. nonce: -COW4-
.. section: Library

Make the :class:`array.array` type immutable. Patch by Erlend E. Aasland.

..

.. bpo: 43901
.. date: 2021-04-25-22-50-47
.. nonce: oKjG5E
.. section: Core and Builtins

Change class and module objects to lazy-create empty annotations dicts on
demand.  The annotations dicts are stored in the object's __dict__ for
backwards compatibility.

..

.. bpo: 43892
.. date: 2021-04-25-08-35-11
.. nonce: hr5Ke2
.. section: Core and Builtins

Match patterns now use new dedicated AST nodes (``MatchValue``,
``MatchSingleton``, ``MatchSequence``, ``MatchStar``, ``MatchMapping``,
``MatchClass``) rather than reusing expression AST nodes. ``MatchAs`` and
``MatchOr`` are now defined as pattern nodes rather than as expression
nodes. Patch by Nick Coghlan.

..

.. bpo: 42725
.. date: 2021-04-25-05-40-51
.. nonce: WGloYm
.. section: Core and Builtins

Usage of ``await``/``yield``/``yield from`` and named expressions within an
annotation is now forbidden when PEP 563 is activated.

..

.. bpo: 43754
.. date: 2021-04-24-16-40-23
.. nonce: 9SzHWG
.. section: Core and Builtins

When performing structural pattern matching (:pep:`634`), captured names are
now left unbound until the *entire* pattern has matched successfully.

..

.. bpo: 42737
.. date: 2021-04-22-22-48-30
.. nonce: lsJ7pD
.. section: Core and Builtins

Annotations for complex targets (everything beside simple names) no longer
cause any runtime effects with ``from __future__ import annotations``.

..

.. bpo: 43914
.. date: 2021-04-22-19-09-58
.. nonce: 0Ik1AM
.. section: Core and Builtins

:exc:`SyntaxError` exceptions raised by the interpreter will highlight the
full error range of the expression that constitutes the syntax error itself,
instead of just where the problem is detected. Patch by Pablo Galindo.

..

.. bpo: 38605
.. date: 2021-04-20-22-17-47
.. nonce: 9eeCNZ
.. section: Core and Builtins

Revert making ``from __future__ import annotations`` the default. This
follows the Steering Council decision to postpone PEP 563 changes to at
least Python 3.11. See the original email for more information regarding the
decision:
https://mail.python.org/archives/list/python-dev@python.org/thread/CLVXXPQ2T2LQ5MP2Y53VVQFCXYWQJHKZ/.
Patch by Pablo Galindo.

..

.. bpo: 43475
.. date: 2021-04-20-20-10-46
.. nonce: oV8Mbs
.. section: Core and Builtins

Hashes of NaN values now depend on object identity.  Formerly, they always
hashed to 0 even though NaN values are not equal to one another.  Having the
same hash for unequal values caused pile-ups in hash tables.

..

.. bpo: 43859
.. date: 2021-04-16-01-26-57
.. nonce: QfqjFL
.. section: Core and Builtins

Improve the error message for :exc:`IndentationError` exceptions. Patch by
Pablo Galindo

..

.. bpo: 41323
.. date: 2021-04-15-10-19-59
.. nonce: nsvpSg
.. section: Core and Builtins

Constant tuple folding in bytecode optimizer now reuses tuple in constant
table.

..

.. bpo: 43846
.. date: 2021-04-14-13-53-08
.. nonce: 2jO97c
.. section: Core and Builtins

Data stack usage is much reduced for large literal and call expressions.

..

.. bpo: 38530
.. date: 2021-04-14-03-53-06
.. nonce: rNI_G1
.. section: Core and Builtins

When printing :exc:`NameError` raised by the interpreter,
:c:func:`PyErr_Display` will offer suggestions of similar variable names in
the function that the exception was raised from. Patch by Pablo Galindo

..

.. bpo: 43823
.. date: 2021-04-13-03-06-09
.. nonce: xpuHBi
.. section: Core and Builtins

Improve syntax errors for invalid dictionary literals. Patch by Pablo
Galindo.

..

.. bpo: 43822
.. date: 2021-04-13-02-32-18
.. nonce: lej0OO
.. section: Core and Builtins

Improve syntax errors in the parser for missing commas between expressions.
Patch by Pablo Galindo.

..

.. bpo: 43798
.. date: 2021-04-10-00-01-43
.. nonce: p_nJFM
.. section: Core and Builtins

:class:`ast.alias` nodes now include source location metadata attributes
e.g. lineno, col_offset.

..

.. bpo: 43797
.. date: 2021-04-09-19-12-48
.. nonce: HfRqNP
.. section: Core and Builtins

Improve ``SyntaxError`` error messages for invalid comparisons. Patch by
Pablo Galindo.

..

.. bpo: 43760
.. date: 2021-04-08-12-20-29
.. nonce: tBIsD8
.. section: Core and Builtins

Move the flag for checking whether tracing is enabled to the C stack, from
the heap. Should speed up dispatch in the interpreter.

..

.. bpo: 43682
.. date: 2021-04-08-01-06-22
.. nonce: eUn4p5
.. section: Core and Builtins

Static methods (:deco:`staticmethod`) and class methods
(:deco:`classmethod`) now inherit the method attributes
(``__module__``, ``__name__``, ``__qualname__``, ``__doc__``,
``__annotations__``) and have a new ``__wrapped__`` attribute. Patch by
Victor Stinner.

..

.. bpo: 43751
.. date: 2021-04-07-18-00-05
.. nonce: 8fHsqQ
.. section: Core and Builtins

Fixed a bug where ``anext(ait, default)`` would erroneously return None.

..

.. bpo: 42128
.. date: 2021-04-05-17-38-08
.. nonce: 1uVeGK
.. section: Core and Builtins

:data:`~object.__match_args__` is no longer allowed to be a list.

..

.. bpo: 43683
.. date: 2021-04-01-12-30-30
.. nonce: AjxOx2
.. section: Core and Builtins

Add GEN_START opcode. Marks start of generator, including async, or
coroutine and handles sending values to a newly created generator or
coroutine.

..

.. bpo: 43105
.. date: 2021-03-31-20-35-11
.. nonce: PBVmHm
.. section: Library

Importlib now resolves relative paths when creating module spec objects from
file locations.

..

.. bpo: 43682
.. date: 2021-03-31-16-32-57
.. nonce: VSF3vg
.. section: Core and Builtins

Static methods (:deco:`staticmethod`) are now callable as
regular functions. Patch by Victor Stinner.

..

.. bpo: 42609
.. date: 2020-12-12-14-28-31
.. nonce: Qcd54b
.. section: Core and Builtins

Prevented crashes in the AST validator and optimizer when compiling some
absurdly long expressions like ``"+0"*1000000``. :exc:`RecursionError` is
now raised instead.

..

.. bpo: 38530
.. date: 2019-10-27-20-20-07
.. nonce: ZyoDNn
.. section: Core and Builtins

When printing :exc:`AttributeError`, :c:func:`PyErr_Display` will offer
suggestions of similar attribute names in the object that the exception was
raised from. Patch by Pablo Galindo

..

.. bpo: 44015
.. date: 2021-05-03-03-03-49
.. nonce: V5936k
.. section: Library

In @dataclass(), raise a TypeError if KW_ONLY is specified more than once.

..

.. bpo: 25478
.. date: 2021-05-02-19-17-20
.. nonce: AwlwdA
.. section: Library

Added a *total()* method to collections.Counter() to compute the sum of the
counts.

..

.. bpo: 43733
.. date: 2021-05-01-22-59-20
.. nonce: gJWwEQ
.. section: Library

Change :class:`netrc.netrc` to use UTF-8 encoding before using locale
encoding.

..

.. bpo: 43979
.. date: 2021-05-01-01-36-51
.. nonce: 43oJ9L
.. section: Library

Removed an unnecessary list comprehension before looping from
:func:`urllib.parse.parse_qsl`.  Patch by Christoph Zwerschke and Donghee
Na.

..

.. bpo: 43993
.. date: 2021-04-30-19-23-45
.. nonce: T7_yoq
.. section: Library

Update bundled pip to 21.1.1.

..

.. bpo: 43957
.. date: 2021-04-27-12-13-51
.. nonce: 6EaPD-
.. section: Library

[Enum] Deprecate ``TypeError`` when non-member is used in a containment
check; In 3.12 ``True`` or ``False`` will be returned instead, and
containment will return ``True`` if the value is either a member of that
enum or one of its members' value.

..

.. bpo: 42904
.. date: 2021-04-26-23-39-47
.. nonce: ejjsyR
.. section: Library

For backwards compatibility with previous minor versions of Python, if
:func:`typing.get_type_hints` receives no namespace dictionary arguments,
:func:`typing.get_type_hints` will search through the global then local
namespaces during evaluation of stringized type annotations (string forward
references) inside a class.

..

.. bpo: 43945
.. date: 2021-04-26-20-52-16
.. nonce: NgERXO
.. section: Library

[Enum] Deprecate non-standard mixin format() behavior: in 3.12 the enum
member, not the member's value, will be used for format() calls.

..

.. bpo: 41139
.. date: 2021-04-26-17-47-48
.. nonce: ROhn1k
.. section: Library

Deprecate undocumented ``cgi.log()`` API.

..

.. bpo: 43937
.. date: 2021-04-25-13-34-13
.. nonce: isx95l
.. section: Library

Fixed the :mod:`turtle` module working with non-default root window.

..

.. bpo: 43930
.. date: 2021-04-24-14-23-07
.. nonce: R7ah0m
.. section: Library

Update bundled pip to 21.1 and setuptools to 56.0.0

..

.. bpo: 43907
.. date: 2021-04-23-20-57-20
.. nonce: 3RJEjv
.. section: Library

Fix a bug in the pure-Python pickle implementation when using protocol 5,
where bytearray instances that occur several time in the pickled object
graph would incorrectly unpickle into repeated copies of the bytearray
object.

..

.. bpo: 43926
.. date: 2021-04-23-17-48-55
.. nonce: HMUlGU
.. section: Library

In ``importlib.metadata``, provide a uniform interface to ``Description``,
allow for any field to be encoded with multiline values, remove continuation
lines from multiline values, and add a ``.json`` property for easy access to
the PEP 566 JSON-compatible form. Sync with ``importlib_metadata 4.0``.

..

.. bpo: 43920
.. date: 2021-04-23-11-54-38
.. nonce: cJMQ2D
.. section: Library

OpenSSL 3.0.0: :meth:`~ssl.SSLContext.load_verify_locations` now returns a
consistent error message when cadata contains no valid certificate.

..

.. bpo: 43607
.. date: 2021-04-22-22-39-58
.. nonce: 7IYDkG
.. section: Library

:mod:`urllib` can now convert Windows paths with ``\\?\`` prefixes into URL
paths.

..

.. bpo: 43817
.. date: 2021-04-22-04-12-13
.. nonce: FQ-XlH
.. section: Library

Add :func:`inspect.get_annotations`, which safely computes the annotations
defined on an object.  It works around the quirks of accessing the
annotations from various types of objects, and makes very few assumptions
about the object passed in. :func:`inspect.get_annotations` can also
correctly un-stringize stringized annotations.

:func:`inspect.signature`, :func:`inspect.from_callable`, and
:func:`inspect.from_function` now call :func:`inspect.get_annotations` to
retrieve annotations.  This means :func:`inspect.signature` and
:func:`inspect.from_callable` can now un-stringize stringized annotations,
too.

..

.. bpo: 43284
.. date: 2021-04-21-14-50-57
.. nonce: 2QZn2T
.. section: Library

platform.win32_ver derives the windows version from
sys.getwindowsversion().platform_version which in turn derives the version
from kernel32.dll (which can be of a different version than Windows itself).
Therefore change the platform.win32_ver to determine the version using the
platform module's _syscmd_ver private function to return an accurate
version.

..

.. bpo: 42854
.. date: 2021-04-19-03-54-29
.. nonce: Y4M7Tv
.. section: Library

The :mod:`ssl` module now uses ``SSL_read_ex`` and ``SSL_write_ex``
internally. The functions support reading and writing of data larger than 2
GB. Writing zero-length data no longer fails with a protocol violation
error.

..

.. bpo: 42333
.. date: 2021-04-17-19-31-17
.. nonce: cgbtZO
.. section: Library

Port ``_ssl`` extension module to multiphase initialization.

..

.. bpo: 43880
.. date: 2021-04-17-13-53-33
.. nonce: -fC2JD
.. section: Library

:mod:`ssl` now raises DeprecationWarning for OP_NO_SSL/TLS* options, old TLS
versions, old protocols, and other features that have been deprecated since
Python 3.6, 3.7, or OpenSSL 1.1.0.

..

.. bpo: 41559
.. date: 2021-04-17-10-49-57
.. nonce: caIwt9
.. section: Library

:pep:`612` is now implemented purely in Python; builtin
``types.GenericAlias`` objects no longer include ``typing.ParamSpec`` in
``__parameters__`` (with the exception of ``collections.abc.Callable``\ 's
``GenericAlias``). This means previously invalid uses of ``ParamSpec`` (such
as ``list[P]``) which worked in earlier versions of Python 3.10 alpha, will
now raise ``TypeError`` during substitution.

..

.. bpo: 43867
.. date: 2021-04-16-16-46-44
.. nonce: xT9QjF
.. section: Library

The :mod:`multiprocessing` ``Server`` class now explicitly catches
:exc:`SystemExit` and closes the client connection in this case. It happens
when the ``Server.serve_client()`` method reaches the end of file (EOF).

..

.. bpo: 40443
.. date: 2021-04-16-02-03-00
.. nonce: Io6FHL
.. section: Library

Remove unused imports: pyclbr no longer uses copy, and typing no longer uses
ast. Patch by Victor Stinner.

..

.. bpo: 43820
.. date: 2021-04-12-18-01-10
.. nonce: YkqYW4
.. section: Library

Remove an unneeded copy of the namespace passed to
dataclasses.make_dataclass().

..

.. bpo: 43787
.. date: 2021-04-12-15-15-50
.. nonce: wCy_Wd
.. section: Library

Add ``__iter__()`` method to :class:`bz2.BZ2File`, :class:`gzip.GzipFile`,
and :class:`lzma.LZMAFile`. It makes iterating them about 2x faster. Patch
by Inada Naoki.

..

.. bpo: 43680
.. date: 2021-04-12-11-20-34
.. nonce: SR0Epv
.. section: Library

Deprecate io.OpenWrapper and _pyio.OpenWrapper: use io.open and _pyio.open
instead. Until Python 3.9, _pyio.open was not a static method and
builtins.open was set to OpenWrapper to not become a bound method when set
to a class variable. _io.open is a built-in function whereas _pyio.open is a
Python function. In Python 3.10, _pyio.open() is now a static method, and
builtins.open() is now io.open().

..

.. bpo: 43680
.. date: 2021-04-12-09-57-37
.. nonce: o1zEk_
.. section: Library

The Python :func:`!_pyio.open` function becomes a static method to behave as
:func:`io.open` built-in function: don't become a bound method when stored
as a class variable. It becomes possible since static methods are now
callable in Python 3.10. Moreover, :func:`!_pyio.OpenWrapper` becomes a
simple alias to :func:`!_pyio.open`. Patch by Victor Stinner.

..

.. bpo: 41515
.. date: 2021-04-12-06-01-10
.. nonce: YaVReb
.. section: Library

Fix :exc:`KeyError` raised in :func:`typing.get_type_hints` due to synthetic
modules that don't appear in ``sys.modules``.

..

.. bpo: 43776
.. date: 2021-04-12-00-00-00
.. nonce: p14y7a
.. section: Library

When :class:`subprocess.Popen` args are provided as a string or as
:class:`pathlib.Path`, the Popen instance repr now shows the right thing.

..

.. bpo: 42248
.. date: 2021-04-11-21-10-57
.. nonce: pedB1E
.. section: Library

[Enum] ensure exceptions raised in ``_missing__`` are released

..

.. bpo: 43744
.. date: 2021-04-11-20-52-32
.. nonce: uf0E68
.. section: Library

fix issue with enum member name matching the start of a private variable
name

..

.. bpo: 43772
.. date: 2021-04-10-19-14-49
.. nonce: Bxq0zQ
.. section: Library

Fixed the return value of ``TypeVar.__ror__``. Patch by Jelle Zijlstra.

..

.. bpo: 43764
.. date: 2021-04-10-18-23-09
.. nonce: Le5KJp
.. section: Library

Add match_args parameter to @dataclass decorator to allow suppression of
__match_args__ generation.

..

.. bpo: 43799
.. date: 2021-04-10-11-35-50
.. nonce: 1iV4pX
.. section: Library

OpenSSL 3.0.0: define ``OPENSSL_API_COMPAT`` 1.1.1 to suppress deprecation
warnings. Python requires OpenSSL 1.1.1 APIs.

..

.. bpo: 43478
.. date: 2021-04-10-03-30-36
.. nonce: iZcBTq
.. section: Library

Mocks can no longer be used as the specs for other Mocks. As a result, an
already-mocked object cannot have an attribute mocked using
``autospec=True`` or be the subject of a ``create_autospec(...)`` call. This
can uncover bugs in tests since these Mock-derived Mocks will always pass
certain tests (e.g. :func:`isinstance`) and builtin assert functions (e.g.
assert_called_once_with) will unconditionally pass.

..

.. bpo: 43794
.. date: 2021-04-09-16-14-22
.. nonce: -1XPDH
.. section: Library

Add :const:`ssl.OP_IGNORE_UNEXPECTED_EOF` constants (OpenSSL 3.0.0)

..

.. bpo: 43785
.. date: 2021-04-09-14-51-58
.. nonce: 1mM5xE
.. section: Library

Improve ``bz2.BZ2File`` performance by removing the RLock from BZ2File. This
makes BZ2File thread unsafe in the face of multiple simultaneous readers or
writers, just like its equivalent classes in :mod:`gzip` and :mod:`lzma`
have always been.  Patch by Inada Naoki.

..

.. bpo: 43789
.. date: 2021-04-09-14-08-03
.. nonce: eaHlAm
.. section: Library

OpenSSL 3.0.0: Don't call the password callback function a second time when
first call has signaled an error condition.

..

.. bpo: 43788
.. date: 2021-04-09-12-08-01
.. nonce: YsvInM
.. section: Library

The header files for :mod:`ssl` error codes are now OpenSSL
version-specific. Exceptions will now show correct reason and library codes.
The ``make_ssl_data.py`` script has been rewritten to use OpenSSL's text
file with error codes.

..

.. bpo: 43766
.. date: 2021-04-09-00-16-22
.. nonce: nYNQP0
.. section: Library

Implement :pep:`647` in the :mod:`typing` module by adding
:data:`TypeGuard`.

..

.. bpo: 25264
.. date: 2021-04-08-22-11-27
.. nonce: b33fa0
.. section: Library

:func:`os.path.realpath` now accepts a *strict* keyword-only argument. When
set to ``True``, :exc:`OSError` is raised if a path doesn't exist or a
symlink loop is encountered.

..

.. bpo: 43780
.. date: 2021-04-08-20-04-46
.. nonce: hUOgCh
.. section: Library

In ``importlib.metadata``, incorporate changes from importlib_metadata 3.10:
Add mtime-based caching during distribution discovery. Flagged use of dict
result from ``entry_points()`` as deprecated.

..

.. gh-issue: 47383
.. date: 2021-04-08-19-32-26
.. nonce: YI1hdL
.. section: Library

The ``P.args`` and ``P.kwargs`` attributes of :class:`typing.ParamSpec` are
now instances of the new classes :class:`typing.ParamSpecArgs` and
:class:`typing.ParamSpecKwargs`, which enables a more useful ``repr()``.
Patch by Jelle Zijlstra.

..

.. bpo: 43731
.. date: 2021-04-08-15-19-20
.. nonce: nnVd3h
.. section: Library

Add an ``encoding`` parameter :func:`logging.fileConfig`.

..

.. bpo: 43712
.. date: 2021-04-08-12-25-08
.. nonce: f8WXCX
.. section: Library

Add ``encoding`` and ``errors`` parameters to :func:`fileinput.input` and
:class:`fileinput.FileInput`.

..

.. bpo: 38659
.. date: 2021-04-08-11-47-31
.. nonce: r_HFnU
.. section: Library

A ``simple_enum`` decorator is added to the ``enum`` module to convert a
normal class into an Enum. ``test_simple_enum`` added to test simple enums
against a corresponding normal Enum.  Standard library modules updated to
use ``simple_enum``.

..

.. bpo: 43764
.. date: 2021-04-08-09-59-20
.. nonce: tHjO60
.. section: Library

Fix an issue where :data:`~object.__match_args__` generation could fail for
some :mod:`dataclasses`.

..

.. bpo: 43752
.. date: 2021-04-06-21-18-29
.. nonce: K7qmAF
.. section: Library

Fix :mod:`sqlite3` regression for zero-sized blobs with converters, where
``b""`` was returned instead of ``None``. The regression was introduced by
PR 24723. Patch by Erlend E. Aasland.

..

.. bpo: 43655
.. date: 2021-04-04-20-51-19
.. nonce: LwGy8R
.. section: Library

:mod:`tkinter` dialog windows are now recognized as dialogs by window
managers on macOS and X Window.

..

.. bpo: 43723
.. date: 2021-04-03-18-03-44
.. nonce: uBhBZS
.. section: Library

The following ``threading`` methods are now deprecated and should be
replaced:

- ``currentThread`` => :func:`threading.current_thread`

- ``activeCount`` => :func:`threading.active_count`

- ``Condition.notifyAll`` => :meth:`threading.Condition.notify_all`

- ``Event.isSet`` => :meth:`threading.Event.is_set`

- ``Thread.setName`` => :attr:`threading.Thread.name`

- ``thread.getName`` => :attr:`threading.Thread.name`

- ``Thread.isDaemon`` => :attr:`threading.Thread.daemon`

- ``Thread.setDaemon`` => :attr:`threading.Thread.daemon`

Patch by Jelle Zijlstra.

..

.. bpo: 2135
.. date: 2021-04-03-15-24-59
.. nonce: xmDAYJ
.. section: Library

Deprecate find_module() and find_loader() implementations in importlib and
zipimport.

..

.. bpo: 43534
.. date: 2021-03-18-15-46-08
.. nonce: vPE9Us
.. section: Library

:func:`turtle.textinput` and :func:`turtle.numinput` create now a transient
window working on behalf of the canvas window.

..

.. bpo: 43532
.. date: 2021-03-17-19-06-45
.. nonce: W2Ntnm
.. section: Library

Add the ability to specify keyword-only fields to dataclasses.  These fields
will become keyword-only arguments to the generated __init__.

..

.. bpo: 43522
.. date: 2021-03-16-22-37-32
.. nonce: dhNwOu
.. section: Library

Fix problem with :attr:`~ssl.SSLContext.hostname_checks_common_name`.
OpenSSL does not copy hostflags from *struct SSL_CTX* to *struct SSL*.

..

.. bpo: 8978
.. date: 2021-03-13-14-02-07
.. nonce: CRxG-O
.. section: Library

Improve error message for :func:`tarfile.open` when :mod:`lzma` / :mod:`bz2`
are unavailable.  Patch by Anthony Sottile.

..

.. bpo: 42967
.. date: 2021-03-11-00-31-41
.. nonce: 2PeQRw
.. section: Library

Allow :class:`bytes` ``separator`` argument in ``urllib.parse.parse_qs`` and
``urllib.parse.parse_qsl`` when parsing :class:`str` query strings.
Previously, this raised a ``TypeError``.

..

.. bpo: 43296
.. date: 2021-03-01-13-01-33
.. nonce: p_gU6T
.. section: Library

Improve :mod:`sqlite3` error handling: ``sqlite3_value_blob()`` errors that
set ``SQLITE_NOMEM`` now raise :exc:`MemoryError`. Patch by Erlend E.
Aasland.

..

.. bpo: 43312
.. date: 2021-02-25-14-43-59
.. nonce: 6dg9_2
.. section: Library

New functions :func:`sysconfig.get_preferred_scheme` and
:func:`sysconfig.get_default_scheme` are added to query a platform for its
preferred "user", "home", and "prefix" (default) scheme names.

..

.. bpo: 43265
.. date: 2021-02-19-22-24-33
.. nonce: MyAzCH
.. section: Library

Improve :meth:`sqlite3.Connection.backup` error handling. The error message
for non-existent target database names is now ``unknown database <database
name>`` instead of ``SQL logic error``. Patch by Erlend E. Aasland.

..

.. bpo: 41282
.. date: 2021-02-16-13-18-38
.. nonce: GK9a0l
.. section: Library

Install schemes in ``distutils.command.install`` are now loaded from
:mod:`sysconfig`.

..

.. bpo: 41282
.. date: 2021-02-15-12-52-23
.. nonce: SenEje
.. section: Library

``distutils.sysconfig`` has been merged to :mod:`sysconfig`.

..

.. bpo: 43176
.. date: 2021-02-09-07-24-29
.. nonce: bocNQn
.. section: Library

Fixed processing of a dataclass that inherits from a frozen dataclass with
no fields.  It is now correctly detected as an error.

..

.. bpo: 43080
.. date: 2021-01-31-00-23-13
.. nonce: -fDg4Q
.. section: Library

:mod:`pprint` now has support for :class:`dataclasses.dataclass`. Patch by
Lewis Gaul.

..

.. bpo: 39950
.. date: 2021-01-22-00-15-37
.. nonce: NzLVaR
.. section: Library

Add ``pathlib.Path.hardlink_to()`` method that supersedes ``link_to()``. The new
method has the same argument order as ``symlink_to()``.

..

.. bpo: 42904
.. date: 2021-01-12-23-17-02
.. nonce: -4qkTD
.. section: Library

:func:`typing.get_type_hints` now checks the local namespace of a class when
evaluating :pep:`563` annotations inside said class.

..

.. bpo: 42269
.. date: 2021-01-08-22-32-13
.. nonce: W5v8z4
.. section: Library

Add ``slots`` parameter to ``dataclasses.dataclass`` decorator to
automatically generate ``__slots__`` for class. Patch provided by Yurii
Karabas.

..

.. bpo: 39529
.. date: 2020-12-06-20-21-16
.. nonce: 9Zrg43
.. section: Library

Deprecated use of :func:`asyncio.get_event_loop` without running event loop.
Emit deprecation warning for :mod:`asyncio` functions which implicitly
create a :class:`~asyncio.Future` or :class:`~asyncio.Task` objects if there
is no running event loop and no explicit *loop* argument is passed:
:func:`~asyncio.ensure_future`, :func:`~asyncio.wrap_future`,
:func:`~asyncio.gather`, :func:`~asyncio.shield`,
:func:`~asyncio.as_completed` and constructors of :class:`~asyncio.Future`,
:class:`~asyncio.Task`, :class:`~asyncio.StreamReader`,
:class:`~asyncio.StreamReaderProtocol`.

..

.. bpo: 18369
.. date: 2020-11-19-09-52-24
.. nonce: qzvYH2
.. section: Library

Certificate and PrivateKey classes were added to the ssl module.
Certificates and keys can now be loaded from memory buffer, too.

..

.. bpo: 41486
.. date: 2020-10-16-15-34-30
.. nonce: Mu9Iit
.. section: Library

Use a new output buffer management code for :mod:`bz2` / :mod:`lzma` /
:mod:`zlib` modules, and add ``.readall()`` function to
``_compression.DecompressReader`` class. These bring some performance
improvements. Patch by Ma Lin.

..

.. bpo: 31870
.. date: 2020-09-15-23-44-07
.. nonce: nVwd38
.. section: Library

The :func:`ssl.get_server_certificate` function now has a *timeout*
parameter.

..

.. bpo: 41735
.. date: 2020-09-07-11-15-15
.. nonce: NKqGKy
.. section: Library

Fix thread locks in zlib module may go wrong in rare case. Patch by Ma Lin.

..

.. bpo: 36470
.. date: 2020-06-13-23-33-32
.. nonce: oi6Kdb
.. section: Library

Fix dataclasses with ``InitVar``\s and :func:`~dataclasses.replace`. Patch
by Claudiu Popa.

..

.. bpo: 40849
.. date: 2020-06-02-21-32-33
.. nonce: zpeKx3
.. section: Library

Expose X509_V_FLAG_PARTIAL_CHAIN ssl flag

..

.. bpo: 35114
.. date: 2020-05-17-14-10-24
.. nonce: uLIHfn
.. section: Library

:func:`ssl.RAND_status` now returns a boolean value (as documented) instead
of ``1`` or ``0``.

..

.. bpo: 39906
.. date: 2020-03-30-00-13-27
.. nonce: eaR3fN
.. section: Library

:meth:`pathlib.Path.stat` and :meth:`~pathlib.Path.chmod` now accept a
*follow_symlinks* keyword-only argument for consistency with corresponding
functions in the :mod:`os` module.

..

.. bpo: 39899
.. date: 2020-03-09-20-36-07
.. nonce: 9adF3E
.. section: Library

:func:`os.path.expanduser` now refuses to guess Windows home directories
if the basename of current user's home directory does not match their
username.

:meth:`pathlib.Path.expanduser` and :meth:`~pathlib.Path.home` now
consistently raise :exc:`RuntimeError` exception when a home directory
cannot be resolved. Previously a :exc:`KeyError` exception could be raised
on Windows when the ``"USERNAME"``  environment variable was unset.

..

.. bpo: 36076
.. date: 2019-10-16-17-21-53
.. nonce: FGeQQT
.. section: Library

Added SNI support to :func:`ssl.get_server_certificate`.

..

.. bpo: 38490
.. date: 2019-10-16-08-08-14
.. nonce: QbDXEF
.. section: Library

Covariance, Pearson's correlation, and simple linear regression
functionality was added to statistics module. Patch by Tymoteusz Wołodźko.

..

.. bpo: 33731
.. date: 2019-08-14-13-19-50
.. nonce: 9esS0d
.. section: Library

Provide a locale.localize() function, which converts a normalized number
string into a locale format.

..

.. bpo: 32745
.. date: 2018-08-09-23-47-10
.. nonce: iQi9hI
.. section: Library

Fix a regression in the handling of ctypes' :data:`ctypes.c_wchar_p` type:
embedded null characters would cause a :exc:`ValueError` to be raised. Patch
by Zackery Spytz.

..

.. bpo: 43987
.. date: 2021-04-30-04-27-02
.. nonce: 1DftVa
.. section: Documentation

Add "Annotations Best Practices" document as a new HOWTO.

..

.. bpo: 43977
.. date: 2021-04-29-15-06-03
.. nonce: K5aSl1
.. section: Documentation

Document the new :c:macro:`Py_TPFLAGS_MAPPING` and
:c:macro:`Py_TPFLAGS_SEQUENCE` type flags.

..

.. bpo: 43959
.. date: 2021-04-27-22-22-22
.. nonce: n2261q
.. section: Documentation

The documentation on the PyContextVar C-API was clarified.

..

.. bpo: 43938
.. date: 2021-04-25-22-44-27
.. nonce: nC660q
.. section: Documentation

Update dataclasses documentation to express that FrozenInstanceError is
derived from AttributeError.

..

.. bpo: 43778
.. date: 2021-04-08-22-42-02
.. nonce: MszRnY
.. section: Documentation

Fix the Sphinx glossary_search extension: create the _static/ sub-directory
if it doesn't exist.

..

.. bpo: 43755
.. date: 2021-04-06-14-55-45
.. nonce: 1m0fGq
.. section: Documentation

Update documentation to reflect that unparenthesized lambda expressions can
no longer be the expression part in an ``if`` clause in comprehensions and
generator expressions since Python 3.9.

..

.. bpo: 43739
.. date: 2021-04-06-07-05-49
.. nonce: L4HjiX
.. section: Documentation

Fixing the example code in Doc/extending/extending.rst to declare and
initialize the pmodule variable to be of the right type.

..

.. bpo: 43961
.. date: 2021-04-28-13-21-52
.. nonce: gNchls
.. section: Tests

Fix test_logging.test_namer_rotator_inheritance() on Windows: use
:func:`os.replace` rather than :func:`os.rename`. Patch by Victor Stinner.

..

.. bpo: 43842
.. date: 2021-04-16-14-07-40
.. nonce: w60GAH
.. section: Tests

Fix a race condition in the SMTP test of test_logging. Don't close a file
descriptor (socket) from a different thread while asyncore.loop() is polling
the file descriptor. Patch by Victor Stinner.

..

.. bpo: 43843
.. date: 2021-04-14-13-22-44
.. nonce: ruIQKD
.. section: Tests

:mod:`test.libregrtest` now marks a test as ENV_CHANGED (altered the
execution environment) if a thread raises an exception but does not catch
it. It sets a hook on :func:`threading.excepthook`. Use
``--fail-env-changed`` option to mark the test as failed. Patch by Victor
Stinner.

..

.. bpo: 43811
.. date: 2021-04-12-11-14-28
.. nonce: vGNbnD
.. section: Tests

Tests multiple OpenSSL versions on GitHub Actions. Use ccache to speed up
testing.

..

.. bpo: 43791
.. date: 2021-04-09-15-10-38
.. nonce: 4KxiXK
.. section: Tests

OpenSSL 3.0.0: Disable testing of legacy protocols TLS 1.0 and 1.1. Tests
are failing with TLSV1_ALERT_INTERNAL_ERROR.

..

.. bpo: 43567
.. date: 2021-03-31-19-50-01
.. nonce: vd0a-p
.. section: Build

Improved generated code refresh (AST/tokens/opcodes/keywords) on Windows.

..

.. bpo: 43669
.. date: 2021-03-30-14-19-39
.. nonce: lWMUYx
.. section: Build

Implement :pep:`644`. Python now requires OpenSSL 1.1.1 or newer.

..

.. bpo: 35306
.. date: 2021-04-22-21-37-41
.. nonce: 10kSR-
.. section: Windows

Adds additional arguments to :func:`os.startfile` function.

..

.. bpo: 43538
.. date: 2021-04-22-20-39-49
.. nonce: F0Cg6X
.. section: Windows

Avoid raising errors from :meth:`pathlib.Path.exists` when passed an
invalid filename.

..

.. bpo: 38822
.. date: 2021-04-22-19-49-20
.. nonce: jgdPmq
.. section: Windows

Fixed :func:`os.stat` failing on inaccessible directories with a trailing
slash, rather than falling back to the parent directory's metadata. This
implicitly affected :func:`os.path.exists` and :func:`os.path.isdir`.

..

.. bpo: 26227
.. date: 2021-04-21-23-37-34
.. nonce: QMY_eA
.. section: Windows

Fixed decoding of host names in :func:`socket.gethostbyaddr` and
:func:`socket.gethostbyname_ex`.

..

.. bpo: 40432
.. date: 2021-04-20-23-07-22
.. nonce: 9OFpoq
.. section: Windows

Updated pegen regeneration script on Windows to find and use Python 3.8 or
higher.  Prior to this, pegen regeneration already required 3.8 or higher,
but the script may have used lower versions of Python.

..

.. bpo: 43745
.. date: 2021-04-06-12-27-33
.. nonce: rdKNda
.. section: Windows

Actually updates Windows release to OpenSSL 1.1.1k. Earlier releases were
mislabelled and actually included 1.1.1i again.

..

.. bpo: 43652
.. date: 2021-04-03-18-54-31
.. nonce: gNmfVN
.. section: Windows

Update Tcl and Tk to 8.6.11 in Windows installer.

..

.. bpo: 43492
.. date: 2021-03-15-11-34-33
.. nonce: AsYnVX
.. section: Windows

Upgrade Windows installer to use SQLite 3.35.5.

..

.. bpo: 30555
.. date: 2017-12-16-12-23-51
.. nonce: 3ybjly
.. section: Windows

Fix ``WindowsConsoleIO`` errors in the presence of fd redirection. Patch by
Segev Finer.

..

.. bpo: 42119
.. date: 2021-05-02-21-03-27
.. nonce: Y7BSX_
.. section: macOS

Fix check for macOS SDK paths when building Python. Narrow search to match
contents of SDKs, namely only files in ``/System/Library``,
``/System/IOSSupport``, and ``/usr`` other than ``/usr/local``. Previously,
anything under ``/System`` was assumed to be in an SDK which causes problems
with the new file system layout in 10.15+ where user file systems may appear
to be mounted under ``/System``.  Paths in ``/Library`` were also
incorrectly treated as SDK locations.

..

.. bpo: 43568
.. date: 2021-05-02-19-50-52
.. nonce: AeLNBd
.. section: macOS

Drop support for MACOSX_DEPLOYMENT_TARGET < 10.3

..

.. bpo: 44009
.. date: 2021-05-02-03-45-30
.. nonce: uvhmlh
.. section: macOS

Provide "python3.x-intel64" executable to allow reliably forcing macOS
universal2 framework builds to run under Rosetta 2 Intel-64 emulation on
Apple Silicon Macs.  This can be useful for testing or when universal2
wheels are not yet available.

..

.. bpo: 43851
.. date: 2021-04-15-01-20-45
.. nonce: sDI60Y
.. section: macOS

Build SQLite with ``SQLITE_OMIT_AUTOINIT`` on macOS. Patch by Erlend E.
Aasland.

..

.. bpo: 43492
.. date: 2021-03-15-11-32-23
.. nonce: 1ZRcV9
.. section: macOS

Update macOS installer to use SQLite 3.35.4.

..

.. bpo: 42235
.. date: 2020-11-01-17-37-16
.. nonce: A97_BN
.. section: macOS

``Mac/BuildScript/build-installer.py`` will now use "--enable-optimizations"
and ``--with-lto`` when building on macOS 10.15 or later.

..

.. bpo: 37903
.. date: 2021-05-02-20-25-53
.. nonce: VQ6VTU
.. section: IDLE

Add mouse actions to the shell sidebar.  Left click and optional drag
selects one or more lines, as with the editor line number sidebar.  Right
click after selecting raises a context menu with 'copy with prompts'.  This
zips together prompts from the sidebar with lines from the selected text.

..

.. bpo: 43981
.. date: 2021-04-30-17-59-56
.. nonce: 3EFl1H
.. section: IDLE

Fix reference leak in test_sidebar and test_squeezer.
Patches by Terry Jan Reedy and Pablo Galindo

..

.. bpo: 37892
.. date: 2021-04-29-02-40-41
.. nonce: bgW2fk
.. section: IDLE

Indent IDLE Shell input with spaces instead of tabs

..

.. bpo: 43655
.. date: 2021-04-04-20-52-07
.. nonce: HSyaKH
.. section: IDLE

IDLE dialog windows are now recognized as dialogs by window managers on
macOS and X Window.

..

.. bpo: 37903
.. date: 2019-08-24-23-49-36
.. nonce: 4xjast
.. section: IDLE

IDLE's shell now shows prompts in a separate side-bar.

..

.. bpo: 43916
.. date: 2021-04-29-17-35-48
.. nonce: wvWt23
.. section: C API

Add a new :c:macro:`Py_TPFLAGS_DISALLOW_INSTANTIATION` type flag to disallow
creating type instances. Patch by Victor Stinner.

..

.. bpo: 43774
.. date: 2021-04-29-10-17-21
.. nonce: 5MGfgN
.. section: C API

Remove the now unused ``PYMALLOC_DEBUG`` macro. Debug hooks on memory
allocators are now installed by default if Python is built in debug mode (if
``Py_DEBUG`` macro is defined). Moreover, they can now be used on Python
build in release mode (ex: using ``PYTHONMALLOC=debug`` environment
variable).

..

.. bpo: 43962
.. date: 2021-04-28-13-13-07
.. nonce: 9Jzs5X
.. section: C API

_PyInterpreterState_IDIncref() now calls _PyInterpreterState_IDInitref() and
always increments id_refcount. Previously, calling
_xxsubinterpreters.get_current() could create an id_refcount inconsistency
when a _xxsubinterpreters.InterpreterID object was deallocated. Patch by
Victor Stinner.

..

.. bpo: 28254
.. date: 2021-04-28-12-33-44
.. nonce: a2561e
.. section: C API

Add new C-API functions to control the state of the garbage collector:
:c:func:`PyGC_Enable()`, :c:func:`PyGC_Disable()`,
:c:func:`PyGC_IsEnabled()`, corresponding to the functions in the :mod:`gc`
module.

..

.. bpo: 43908
.. date: 2021-04-22-10-46-40
.. nonce: Co3YhZ
.. section: C API

Introduce :c:macro:`Py_TPFLAGS_IMMUTABLETYPE` flag for immutable type objects,
and modify :c:func:`PyType_Ready` to set it for static types. Patch by
Erlend E. Aasland.

..

.. bpo: 43795
.. date: 2021-04-20-15-06-29
.. nonce: y0IP4c
.. section: C API

:c:func:`PyMem_Calloc` is now available in the limited C API
(``Py_LIMITED_API``).

..

.. bpo: 43868
.. date: 2021-04-16-18-15-56
.. nonce: twQ7KH
.. section: C API

:c:func:`PyOS_ReadlineFunctionPointer` is no longer exported by limited C
API headers and by ``python3.dll`` on Windows. Like any function that takes
``FILE*``, it is not part of the stable ABI.

..

.. bpo: 43795
.. date: 2021-04-09-18-19-07
.. nonce: l0yobT
.. section: C API

Stable ABI and limited API definitions are generated from a central manifest
(:pep:`652`).

..

.. bpo: 43753
.. date: 2021-04-06-20-52-44
.. nonce: xUsHp1
.. section: C API

Add the :c:func:`Py_Is(x, y) <Py_Is>` function to test if the *x* object is
the *y* object, the same as ``x is y`` in Python. Add also the
:c:func:`Py_IsNone`, :c:func:`Py_IsTrue`, :c:func:`Py_IsFalse` functions to
test if an object is, respectively, the ``None`` singleton, the ``True``
singleton or the ``False`` singleton. Patch by Victor Stinner.
