.. bpo: 41304
.. date: 2020-07-15-20-15-08
.. nonce: vNEeYA
.. release date: 2020-10-05
.. section: Security

Fixes ``python3x._pth`` being ignored on Windows, caused by the fix for
:issue:`29778` (:cve:`2020-15801`).

..

.. bpo: 41162
.. date: 2020-07-03-20-41-29
.. nonce: tb8pVj
.. section: Security

Audit hooks are now cleared later during finalization to avoid missing
events.

..

.. bpo: 29778
.. date: 2020-07-03-17-21-37
.. nonce: cR_fGS
.. section: Security

Ensure :file:`python3.dll` is loaded from correct locations when Python is
embedded (:cve:`2020-15523`).

..

.. bpo: 41004
.. date: 2020-06-29-16-02-29
.. nonce: ovF0KZ
.. section: Security

The __hash__() methods of  ipaddress.IPv4Interface and
ipaddress.IPv6Interface incorrectly generated constant hash values of 32 and
128 respectively. This resulted in always causing hash collisions. The fix
uses hash() to generate hash values for the tuple of (address, mask length,
network address).

..

.. bpo: 39603
.. date: 2020-02-12-14-17-39
.. nonce: Gt3RSg
.. section: Security

Prevent http header injection by rejecting control characters in
http.client.putrequest(...).

..

.. bpo: 41909
.. date: 2020-10-04-10-55-12
.. nonce: BqHPcm
.. section: Core and Builtins

Fixed stack overflow in :func:`issubclass` and :func:`isinstance` when
getting the ``__bases__`` attribute leads to infinite recursion.

..

.. bpo: 41922
.. date: 2020-10-04-01-02-58
.. nonce: kHGT8I
.. section: Core and Builtins

Speed up calls to ``reversed()`` by using the :pep:`590` ``vectorcall``
calling convention. Patch by Donghee Na.

..

.. bpo: 41873
.. date: 2020-09-28-08-58-28
.. nonce: VzEDhA
.. section: Core and Builtins

Calls to ``float()`` are now faster due to the ``vectorcall`` calling
convention. Patch by Dennis Sweeney.

..

.. bpo: 41870
.. date: 2020-09-27-22-23-14
.. nonce: 2v6_v4
.. section: Core and Builtins

Speed up calls to ``bool()`` by using the :pep:`590` ``vectorcall`` calling
convention. Patch by Donghee Na.

..

.. bpo: 1635741
.. date: 2020-09-26-14-43-30
.. nonce: aJS9B3
.. section: Core and Builtins

Port the :mod:`_bisect` module to the multi-phase initialization API
(:pep:`489`).

..

.. bpo: 39934
.. date: 2020-09-24-12-15-45
.. nonce: YVHTCF
.. section: Core and Builtins

Correctly count control blocks in 'except' in compiler. Ensures that a
syntax error, rather a fatal error, occurs for deeply nested, named
exception handlers.

..

.. bpo: 41780
.. date: 2020-09-15-23-29-49
.. nonce: bOBUIH
.. section: Core and Builtins

Fix :meth:`__dir__` of :class:`types.GenericAlias`. Patch by Batuhan
Taskaya.

..

.. bpo: 1635741
.. date: 2020-09-12-18-34-34
.. nonce: lh335O
.. section: Core and Builtins

Port the :mod:`_lsprof` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-08-21-58-47
.. nonce: vdjSLH
.. section: Core and Builtins

Port the :mod:`cmath` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-08-20-39-43
.. nonce: jiXmyT
.. section: Core and Builtins

Port the :mod:`_scproxy` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-07-11-35-02
.. nonce: rvIexb
.. section: Core and Builtins

Port the :mod:`termios` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-07-09-45-47
.. nonce: QuDIut
.. section: Core and Builtins

Convert the :mod:`_sha256` extension module types to heap types.

..

.. bpo: 41690
.. date: 2020-09-02-12-00-57
.. nonce: Ny-Sfy
.. section: Core and Builtins

Fix a possible stack overflow in the parser when parsing functions and
classes with a huge amount of arguments. Patch by Pablo Galindo.

..

.. bpo: 1635741
.. date: 2020-09-01-17-22-35
.. nonce: CnRME3
.. section: Core and Builtins

Port the :mod:`_overlapped` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-01-17-08-07
.. nonce: X9CZgo
.. section: Core and Builtins

Port the :mod:`_curses_panel` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-01-17-06-02
.. nonce: 5jZymK
.. section: Core and Builtins

Port the :mod:`_opcode` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 41681
.. date: 2020-08-31-17-49-02
.. nonce: 3-VJiH
.. section: Core and Builtins

Fixes the wrong error description in the error raised by using 2 ``,`` in
format string in f-string and :meth:`str.format`.

..

.. bpo: 41675
.. date: 2020-08-31-14-53-17
.. nonce: VSoqWU
.. section: Core and Builtins

The implementation of :func:`signal.siginterrupt` now uses
:c:func:`!sigaction` (if it is available in the system) instead of the
deprecated :c:func:`!siginterrupt`. Patch by Pablo Galindo.

..

.. bpo: 41670
.. date: 2020-08-31-11-37-59
.. nonce: vmRJRx
.. section: Core and Builtins

Prevent line trace being skipped on platforms not compiled with
``USE_COMPUTED_GOTOS``. Fixes issue where some lines nested within a
try-except block were not being traced on Windows.

..

.. bpo: 41654
.. date: 2020-08-30-20-38-33
.. nonce: HtnhAM
.. section: Core and Builtins

Fix a crash that occurred when destroying subclasses of
:class:`MemoryError`. Patch by Pablo Galindo.

..

.. bpo: 1635741
.. date: 2020-08-28-20-54-04
.. nonce: 7ijlcI
.. section: Core and Builtins

Port the :mod:`zlib` extension module to multi-phase initialization
(:pep:`489`).

..

.. bpo: 41631
.. date: 2020-08-26-11-23-31
.. nonce: 3jZcd9
.. section: Core and Builtins

The ``_ast`` module uses again a global state. Using a module state per
module instance is causing subtle practical problems. For example, the
Mercurial project replaces the ``__import__()`` function to implement lazy
import, whereas Python expected that ``import _ast`` always return a fully
initialized ``_ast`` module.

..

.. bpo: 40077
.. date: 2020-08-25-22-43-33
.. nonce: vcxSUa
.. section: Core and Builtins

Convert :mod:`_operator` to use :c:func:`PyType_FromSpec`.

..

.. bpo: 1653741
.. date: 2020-08-13-07-19-21
.. nonce: fubBkb
.. section: Core and Builtins

Port :mod:`_sha3` to multi-phase init.  Convert static types to heap types.

..

.. bpo: 1635741
.. date: 2020-08-13-07-18-05
.. nonce: FC13e7
.. section: Core and Builtins

Port the :mod:`_blake2` extension module to the multi-phase initialization
API (:pep:`489`).

..

.. bpo: 41533
.. date: 2020-08-12-20-29-57
.. nonce: 4pcVAc
.. section: Core and Builtins

Free the stack allocated in ``va_build_stack`` if ``do_mkstack`` fails and
the stack is not a ``small_stack``.

..

.. bpo: 41531
.. date: 2020-08-12-19-32-15
.. nonce: WgPzjT
.. section: Core and Builtins

Fix a bug that was dropping keys when compiling dict literals with more than
0xFFFF elements. Patch by Pablo Galindo.

..

.. bpo: 41525
.. date: 2020-08-12-07-35-07
.. nonce: d9q3XL
.. section: Core and Builtins

The output of ``python --help`` contains now only ASCII characters.

..

.. bpo: 1635741
.. date: 2020-08-10-16-11-32
.. nonce: O0d3ym
.. section: Core and Builtins

Port the :mod:`_sha1`, :mod:`_sha512`, and :mod:`_md5` extension modules to
multi-phase initialization API (:pep:`489`).

..

.. bpo: 41431
.. date: 2020-08-02-15-53-12
.. nonce: TblUBT
.. section: Core and Builtins

Optimize ``dict_merge()`` for copying dict (e.g. ``dict(d)`` and
``{}.update(d)``).

..

.. bpo: 41428
.. date: 2020-07-28-22-43-27
.. nonce: FM6xsI
.. section: Core and Builtins

Implement PEP 604. This supports (int | str) etc. in place of Union[str,
int].

..

.. bpo: 41340
.. date: 2020-07-27-01-50-06
.. nonce: pZXfcF
.. section: Core and Builtins

Removed fallback implementation for ``strdup``.

..

.. bpo: 38156
.. date: 2020-07-20-17-01-17
.. nonce: ptcdRy
.. section: Core and Builtins

Handle interrupts that come after EOF correctly in ``PyOS_StdioReadline``.

..

.. bpo: 41342
.. date: 2020-07-19-15-40-52
.. nonce: RRk_m_
.. section: Core and Builtins

:func:`round` with integer argument is now faster (9--60%).

..

.. bpo: 41334
.. date: 2020-07-18-18-01-10
.. nonce: t5xMGp
.. section: Core and Builtins

Constructors :func:`str`, :func:`bytes` and :func:`bytearray` are now faster
(around 30--40% for small objects).

..

.. bpo: 41295
.. date: 2020-07-18-08-15-32
.. nonce: pu8Ezo
.. section: Core and Builtins

Resolve a regression in CPython 3.8.4 where defining "__setattr__" in a
multi-inheritance setup and calling up the hierarchy chain could fail if
builtins/extension types were involved in the base types.

..

.. bpo: 41323
.. date: 2020-07-17-11-31-54
.. nonce: ChbZHh
.. section: Core and Builtins

Bytecode optimizations are performed directly on the control flow graph.
This will result in slightly more compact code objects in some
circumstances.

..

.. bpo: 41247
.. date: 2020-07-08-22-03-54
.. nonce: PndYIk
.. section: Core and Builtins

Always cache the running loop holder when running
``asyncio.set_running_loop``.

..

.. bpo: 41252
.. date: 2020-07-08-21-55-23
.. nonce: nBWL-Y
.. section: Core and Builtins

Fix incorrect refcounting in _ssl.c's ``_servername_callback()``.

..

.. bpo: 1635741
.. date: 2020-07-07-16-10-52
.. nonce: zU-H_n
.. section: Core and Builtins

Port :mod:`multiprocessing` to multi-phase initialization

..

.. bpo: 1635741
.. date: 2020-07-06-20-43-19
.. nonce: LYhsni
.. section: Core and Builtins

Port :mod:`winapi` to multiphase initialization

..

.. bpo: 41215
.. date: 2020-07-06-18-36-33
.. nonce: vFGFIz
.. section: Core and Builtins

Use non-NULL default values in the PEG parser keyword list to overcome a bug
that was preventing Python from being properly compiled when using the XLC
compiler. Patch by Pablo Galindo.

..

.. bpo: 41218
.. date: 2020-07-06-13-35-17
.. nonce: oKnSr2
.. section: Core and Builtins

Python 3.8.3 had a regression where compiling with
ast.PyCF_ALLOW_TOP_LEVEL_AWAIT would aggressively mark list comprehension
with CO_COROUTINE. Now only list comprehension making use of async/await
will tagged as so.

..

.. bpo: 1635741
.. date: 2020-07-03-23-10-02
.. nonce: F5coWe
.. section: Core and Builtins

Port :mod:`faulthandler` to multiphase initialization.

..

.. bpo: 1635741
.. date: 2020-07-01-20-17-38
.. nonce: -AtPYu
.. section: Core and Builtins

Port :mod:`sha256` to multiphase initialization

..

.. bpo: 41175
.. date: 2020-06-30-20-17-31
.. nonce: acJoXB
.. section: Core and Builtins

Guard against a NULL pointer dereference within bytearrayobject triggered by
the ``bytearray() + bytearray()`` operation.

..

.. bpo: 41100
.. date: 2020-06-30-04-44-29
.. nonce: PJwA6F
.. section: Core and Builtins

add arm64 to the allowable Mac OS arches in mpdecimal.h

..

.. bpo: 41094
.. date: 2020-06-23-23-26-42
.. nonce: zEIJse
.. section: Core and Builtins

Fix decoding errors with audit when open files with non-ASCII names on
non-UTF-8 locale.

..

.. bpo: 39960
.. date: 2020-06-23-18-32-41
.. nonce: Kez3fP
.. section: Core and Builtins

The "hackcheck" that prevents sneaking around a type's __setattr__() by
calling the superclass method was rewritten to allow C implemented heap
types.

..

.. bpo: 41084
.. date: 2020-06-23-15-10-19
.. nonce: pt3y7F
.. section: Core and Builtins

Prefix the error message with 'f-string: ', when parsing an f-string
expression which throws a :exc:`SyntaxError`.

..

.. bpo: 40521
.. date: 2020-06-23-07-35-11
.. nonce: dMNA6k
.. section: Core and Builtins

Empty frozensets are no longer singletons.

..

.. bpo: 41076
.. date: 2020-06-22-13-22-30
.. nonce: eWYw2N
.. section: Core and Builtins

Pre-feed the parser with the location of the f-string expression, not the
f-string itself, which allows us to skip the shifting of the AST node
locations after the parsing is completed.

..

.. bpo: 41056
.. date: 2020-06-21-19-53-33
.. nonce: IDu_EK
.. section: Core and Builtins

Fixes a reference to deallocated stack space during startup when
constructing sys.path involving a relative symlink when code was supplied
via -c.  (discovered via Coverity)

..

.. bpo: 41061
.. date: 2020-06-21-10-54-02
.. nonce: AHf9MU
.. section: Core and Builtins

Fix incorrect expressions and asserts in hashtable code and tests.

..

.. bpo: 41052
.. date: 2020-06-20-22-46-18
.. nonce: 46MPeF
.. section: Core and Builtins

Opt out serialization/deserialization for _random.Random

..

.. bpo: 40939
.. date: 2020-06-20-19-27-47
.. nonce: jxJ4yn
.. section: Core and Builtins

Rename ``PyPegen*`` functions to ``PyParser*``, so that we can remove the old
set of ``PyParser*`` functions that were using the old parser, but keep
everything backwards-compatible.

..

.. bpo: 35975
.. date: 2020-06-20-17-00-44
.. nonce: UDHCHp
.. section: Core and Builtins

Stefan Behnel reported that cf_feature_version is used even when
PyCF_ONLY_AST is not set. This is against the intention and against the
documented behavior, so it's been fixed.

..

.. bpo: 40939
.. date: 2020-06-20-16-59-02
.. nonce: 6810Ak
.. section: Core and Builtins

Remove the remaining files from the old parser and the :mod:`symbol` module.

..

.. bpo: 40077
.. date: 2020-06-18-19-04-30
.. nonce: _yI-ax
.. section: Core and Builtins

Convert :mod:`_bz2` to use :c:func:`PyType_FromSpec`.

..

.. bpo: 41006
.. date: 2020-06-18-00-07-09
.. nonce: H-wN-d
.. section: Core and Builtins

The ``encodings.latin_1`` module is no longer imported at startup. Now it is
only imported when it is the filesystem encoding or the stdio encoding.

..

.. bpo: 40636
.. date: 2020-06-17-10-27-17
.. nonce: MYaCIe
.. section: Core and Builtins

:func:`zip` now supports :pep:`618`'s ``strict`` parameter, which raises a
:exc:`ValueError` if the arguments are exhausted at different lengths. Patch
by Brandt Bucher.

..

.. bpo: 1635741
.. date: 2020-06-17-00-52-21
.. nonce: 61iyYh
.. section: Core and Builtins

Port :mod:`_gdbm` to multiphase initialization.

..

.. bpo: 40985
.. date: 2020-06-15-16-29-55
.. nonce: IIN_xX
.. section: Core and Builtins

Fix a bug that caused the :exc:`SyntaxError` text to be empty when a file
ends with a line ending in a line continuation character (i.e. backslash).
The error text should contain the text of the last line.

..

.. bpo: 40958
.. date: 2020-06-15-01-20-44
.. nonce: 7O2Wh1
.. section: Core and Builtins

Fix a possible buffer overflow in the PEG parser when gathering information
for emitting syntax errors. Patch by Pablo Galindo.

..

.. bpo: 1635741
.. date: 2020-06-12-22-56-17
.. nonce: mmlp3Q
.. section: Core and Builtins

Port :mod:`_dbm` to multiphase initialization.

..

.. bpo: 40957
.. date: 2020-06-12-12-21-54
.. nonce: Z8n6I6
.. section: Core and Builtins

Fix refleak in _Py_fopen_obj() when PySys_Audit() fails

..

.. bpo: 40950
.. date: 2020-06-12-00-12-28
.. nonce: tzMy7m
.. section: Core and Builtins

Add a state to the :mod:`!nis` module (:pep:`3121`) and apply the multiphase
initialization. Patch by Donghee Na.

..

.. bpo: 40947
.. date: 2020-06-11-16-06-49
.. nonce: 72cZcR
.. section: Core and Builtins

The Python :ref:`Path Configuration <init-path-config>` now takes
:c:member:`PyConfig.platlibdir` in account.

..

.. bpo: 40939
.. date: 2020-06-10-11-27-15
.. nonce: DO-wAI
.. section: Core and Builtins

Remove the old parser, the :mod:`parser` module and all associated support
code, command-line options and environment variables. Patch by Pablo
Galindo.

..

.. bpo: 40847
.. date: 2020-06-09-23-52-32
.. nonce: 4XAACw
.. section: Core and Builtins

Fix a bug where a line with only a line continuation character is not
considered a blank line at tokenizer level. In such cases, more than a
single ``NEWLINE`` token was emitted. The old parser was working around the
issue, but the new parser threw a :exc:`SyntaxError` for valid input due to
this. For example, an empty line following a line continuation character was
interpreted as a :exc:`SyntaxError`.

..

.. bpo: 40890
.. date: 2020-06-09-00-20-13
.. nonce: LoRV-g
.. section: Core and Builtins

Each dictionary view now has a ``mapping`` attribute that provides a
:class:`types.MappingProxyType` wrapping the original dictionary.  Patch
contributed by Dennis Sweeney.

..

.. bpo: 40889
.. date: 2020-06-08-22-46-33
.. nonce: vIBl-W
.. section: Core and Builtins

Improved the performance of symmetric difference operations on dictionary
item views.  Patch by Dennis Sweeney.

..

.. bpo: 40904
.. date: 2020-06-08-01-08-57
.. nonce: 76qQzo
.. section: Core and Builtins

Fix possible segfault in the new PEG parser when parsing f-string containing
yield statements with no value (:code:`f"{yield}"`). Patch by Pablo Galindo

..

.. bpo: 40903
.. date: 2020-06-07-22-50-10
.. nonce: 7dWejS
.. section: Core and Builtins

Fixed a possible segfault in the new PEG parser when producing error
messages for invalid assignments of the form :code:`p=p=`. Patch by Pablo
Galindo

..

.. bpo: 40880
.. date: 2020-06-06-00-23-19
.. nonce: fjdzSh
.. section: Core and Builtins

Fix invalid memory read in the new parser when checking newlines in string
literals. Patch by Pablo Galindo.

..

.. bpo: 40883
.. date: 2020-06-05-23-25-00
.. nonce: M6sQ-Q
.. section: Core and Builtins

Fix memory leak in when parsing f-strings in the new parser. Patch by Pablo
Galindo

..

.. bpo: 40870
.. date: 2020-06-05-12-48-28
.. nonce: 9cd2sk
.. section: Core and Builtins

Raise :exc:`ValueError` when validating custom AST's where the constants
``True``, ``False`` and ``None`` are used within a :class:`ast.Name` node.

..

.. bpo: 40854
.. date: 2020-06-03-13-53-24
.. nonce: O6vfQU
.. section: Core and Builtins

Allow overriding :data:`sys.platlibdir` via a new :envvar:`PYTHONPLATLIBDIR`
environment variable.

..

.. bpo: 40826
.. date: 2020-06-01-20-31-07
.. nonce: XCI4M2
.. section: Core and Builtins

Fix GIL usage in :c:func:`PyOS_Readline`: lock the GIL to set an exception
and pass the Python thread state when checking if there is a pending signal.

..

.. bpo: 1635741
.. date: 2020-05-30-23-23-35
.. nonce: 0D-laM
.. section: Core and Builtins

Port :mod:`fcntl` to multiphase initialization.

..

.. bpo: 19468
.. date: 2020-05-30-23-18-35
.. nonce: S-TA7p
.. section: Core and Builtins

Delete unnecessary instance check in importlib.reload(). Patch by Furkan
Önder.

..

.. bpo: 40824
.. date: 2020-05-30-14-37-18
.. nonce: XR3V5s
.. section: Core and Builtins

Unexpected errors in calling the ``__iter__`` method are no longer masked by
``TypeError`` in the :keyword:`in` operator and functions
:func:`~operator.contains`, :func:`~operator.indexOf` and
:func:`~operator.countOf` of the :mod:`operator` module.

..

.. bpo: 40792
.. date: 2020-05-27-22-37-58
.. nonce: WEDqqU
.. section: Core and Builtins

Attributes ``start``, ``stop`` and ``step`` of the :class:`range` object now
always has exact type :class:`int`.  Previously, they could have been an
instance of a subclass of ``int``.

..

.. bpo: 40780
.. date: 2020-05-26-17-43-58
.. nonce: 3Ckdgm
.. section: Core and Builtins

Fix a corner case where g-style string formatting of a float failed to
remove trailing zeros.

..

.. bpo: 38964
.. date: 2020-05-25-21-49-11
.. nonce: lrml90
.. section: Core and Builtins

When there's a :exc:`SyntaxError` in the expression part of an fstring, the
filename attribute of the :exc:`SyntaxError` gets correctly set to the name
of the file the fstring resides in.

..

.. bpo: 40750
.. date: 2020-05-24-02-42-26
.. nonce: ZmO9Ev
.. section: Core and Builtins

Support the "-d" debug flag in the new PEG parser. Patch by Pablo Galindo

..

.. bpo: 40217
.. date: 2020-05-23-01-15-51
.. nonce: jZsHTc
.. section: Core and Builtins

Instances of types created with :c:func:`PyType_FromSpecWithBases` will no
longer automatically visit their class object when traversing references in
the garbage collector. The user is expected to manually visit the object's
class. Patch by Pablo Galindo.

..

.. bpo: 39573
.. date: 2020-05-22-00-34-34
.. nonce: QO2QHj
.. section: Core and Builtins

:c:func:`Py_TYPE()` is changed to the inline static function. Patch by
Donghee Na.

..

.. bpo: 40696
.. date: 2020-05-21-01-54-00
.. nonce: u3n8Wx
.. section: Core and Builtins

Fix a hang that can arise after :meth:`generator.throw` due to a cycle in
the exception context chain.

..

.. bpo: 40521
.. date: 2020-05-20-01-17-34
.. nonce: wvAehI
.. section: Core and Builtins

Each interpreter now its has own free lists, singletons and caches:

* Free lists: float, tuple, list, dict, frame, context,
  asynchronous generator, MemoryError.
* Singletons: empty tuple, empty bytes string, empty Unicode string,
  single byte character, single Unicode (latin1) character.
* Slice cache.

They are no longer shared by all interpreters.

..

.. bpo: 40679
.. date: 2020-05-19-19-39-49
.. nonce: SVzz9p
.. section: Core and Builtins

Certain :exc:`TypeError` messages about missing or extra arguments now
include the function's :term:`qualified name`.  Patch by Dennis Sweeney.

..

.. bpo: 29590
.. date: 2020-05-03-22-26-00
.. nonce: aRz3l7
.. section: Core and Builtins

Make the stack trace correct after calling :meth:`generator.throw` on a
generator that has yielded from a ``yield from``.

..

.. bpo: 4022
.. date: 2020-04-11-13-07-49
.. nonce: Ctpn_F
.. section: Core and Builtins

Improve performance of generators by not raising internal StopIteration.

..

.. bpo: 1635741
.. date: 2020-04-10-23-54-57
.. nonce: ZURqoN
.. section: Core and Builtins

Port :mod:`mmap` to multiphase initialization.

..

.. bpo: 1635741
.. date: 2020-04-05-02-35-08
.. nonce: Kfe9fT
.. section: Core and Builtins

Port :mod:`_lzma` to multiphase initialization.

..

.. bpo: 37999
.. date: 2019-09-01-14-26-02
.. nonce: XPl6dn
.. section: Core and Builtins

Builtin and extension functions that take integer arguments no longer accept
:class:`~decimal.Decimal`\ s, :class:`~fractions.Fraction`\ s and other
objects that can be converted to integers only with a loss (e.g. that have
the :meth:`~object.__int__` method but do not have the
:meth:`~object.__index__` method).

..

.. bpo: 29882
.. date: 2019-06-02-11-29-15
.. nonce: AkRzjb
.. section: Core and Builtins

Add :meth:`int.bit_count()`, counting the number of ones in the binary
representation of an integer. Patch by Niklas Fiekas.

..

.. bpo: 36982
.. date: 2019-05-25-05-27-39
.. nonce: 0UHgfB
.. section: Core and Builtins

Use ncurses extended color functions when available to support terminals
with 256 colors, and add the new function
:func:`curses.has_extended_color_support` to indicate whether extended color
support is provided by the underlying ncurses library.

..

.. bpo: 19569
.. date: 2018-08-29-15-57-07
.. nonce: RGu2Kb
.. section: Core and Builtins

Add the private macros ``_Py_COMP_DIAG_PUSH``,
``_Py_COMP_DIAG_IGNORE_DEPR_DECLS``, and ``_Py_COMP_DIAG_POP``.

..

.. bpo: 26680
.. date: 2018-03-15-11-51-36
.. nonce: wOWYps
.. section: Core and Builtins

The int type now supports the x.is_integer() method for compatibility with
float.

..

.. bpo: 41900
.. date: 2020-10-01-10-50-12
.. nonce: Cho7oh
.. section: Library

C14N 2.0 serialisation in xml.etree.ElementTree failed for unprefixed
attributes when a default namespace was defined.

..

.. bpo: 41887
.. date: 2020-09-30-23-49-42
.. nonce: -ee2S-
.. section: Library

Strip leading spaces and tabs on :func:`ast.literal_eval`. Also document
stripping of spaces and tabs for :func:`eval`.

..

.. bpo: 41773
.. date: 2020-09-28-23-22-25
.. nonce: oKkus0
.. section: Library

Note in documentation that :func:`random.choices` doesn't support non-finite
weights, raise :exc:`ValueError` when given non-finite weights.

..

.. bpo: 41840
.. date: 2020-09-23-23-17-59
.. nonce: QRFr4L
.. section: Library

Fix a bug in the :mod:`symtable` module that was causing module-scope global
variables to not be reported as both local and global. Patch by Pablo
Galindo.

..

.. bpo: 41842
.. date: 2020-09-23-22-52-24
.. nonce: lIuhC9
.. section: Library

Add :func:`codecs.unregister` function to unregister a codec search
function.

..

.. bpo: 40564
.. date: 2020-09-23-03-33-37
.. nonce: iXQqMq
.. section: Library

In ``zipfile.Path``, mutate the passed ZipFile object type instead of making
a copy. Prevents issues when both the local copy and the caller’s copy
attempt to close the same file handle.

..

.. bpo: 40670
.. date: 2020-09-22-14-55-34
.. nonce: R5sm68
.. section: Library

More reliable validation of statements in :class:`timeit.Timer`. It now
accepts "empty" statements (only whitespaces and comments) and rejects
misindentent statements.

..

.. bpo: 41833
.. date: 2020-09-22-13-51-14
.. nonce: 6HVDjT
.. section: Library

The :class:`threading.Thread` constructor now uses the target name if the
*target* argument is specified but the *name* argument is omitted.

..

.. bpo: 41817
.. date: 2020-09-22-00-23-30
.. nonce: bnh-VG
.. section: Library

fix ``tkinter.EventType`` Enum so all members are strings, and none are tuples

..

.. bpo: 41810
.. date: 2020-09-20-15-14-05
.. nonce: 7l8lyV
.. section: Library

:data:`types.EllipsisType`, :data:`types.NotImplementedType` and
:data:`types.NoneType` have been reintroduced, providing a new set of types
readily interpretable by static type checkers.

..

.. bpo: 41815
.. date: 2020-09-19-23-14-54
.. nonce: RNpuX3
.. section: Library

Fix SQLite3 segfault when backing up closed database. Patch contributed by
Peter David McCormick.

..

.. bpo: 41816
.. date: 2020-09-19-12-22-08
.. nonce: ynynXJ
.. section: Library

StrEnum added: it ensures that all members are already strings or string
candidates

..

.. bpo: 41517
.. date: 2020-09-15-22-43-30
.. nonce: sLBH7g
.. section: Library

fix bug allowing Enums to be extended via multiple inheritance

..

.. bpo: 39587
.. date: 2020-09-15-14-56-13
.. nonce: 69xzuh
.. section: Library

use the correct mix-in data type when constructing Enums

..

.. bpo: 41792
.. date: 2020-09-15-07-55-35
.. nonce: qMpSlU
.. section: Library

Add is_typeddict function to typing.py to check if a type is a TypedDict
class

Previously there was no way to check that without using private API. See the
`relevant issue in python/typing
<https://github.com/python/typing/issues/751>`_.

..

.. bpo: 41789
.. date: 2020-09-14-19-27-46
.. nonce: pI_uZQ
.. section: Library

Honor ``object`` overrides in ``Enum`` class creation (specifically, ``__str__``,
``__repr__``, ``__format__``, and ``__reduce_ex__``).

..

.. bpo: 32218
.. date: 2020-09-12-16-18-42
.. nonce: IpYkEe
.. section: Library

``enum.Flag`` and ``enum.IntFlag`` members are now iterable.

..

.. bpo: 39651
.. date: 2020-09-11-12-38-55
.. nonce: JMp9l2
.. section: Library

Fix a race condition in the ``call_soon_threadsafe()`` method of
``asyncio.ProactorEventLoop``: do nothing if the self-pipe socket has been
closed.

..

.. bpo: 1635741
.. date: 2020-09-08-13-55-34
.. nonce: 56MLP-
.. section: Library

Port the ``mashal`` extension module to the multi-phase initialization API
(:pep:`489`).

..

.. bpo: 1635741
.. date: 2020-09-08-13-51-16
.. nonce: wkPeoT
.. section: Library

Port the ``_string`` extension module to the multi-phase initialization API
(:pep:`489`).

..

.. bpo: 41732
.. date: 2020-09-06-20-27-10
.. nonce: 1SKv26
.. section: Library

Added an :term:`iterator` to :class:`memoryview`.

..

.. bpo: 41720
.. date: 2020-09-04-20-45-38
.. nonce: PW9MzZ
.. section: Library

Fixed :meth:`turtle.Vec2D.__rmul__` for arguments which are not int or
float.

..

.. bpo: 41696
.. date: 2020-09-03-01-35-32
.. nonce: zkYGre
.. section: Library

Fix handling of debug mode in :func:`asyncio.run`. This allows setting
``PYTHONASYNCIODEBUG`` or ``-X dev`` to enable asyncio debug mode when using
:func:`asyncio.run`.

..

.. bpo: 41687
.. date: 2020-09-01-15-57-51
.. nonce: m1b1KA
.. section: Library

Fix implementation of sendfile to be compatible with Solaris.

..

.. bpo: 41662
.. date: 2020-08-30-21-38-57
.. nonce: 6e9iZn
.. section: Library

No longer override exceptions raised in ``__len__()`` of a sequence of
parameters in :mod:`sqlite3` with :exc:`~sqlite3.ProgrammingError`.

..

.. bpo: 39010
.. date: 2020-08-30-10-24-26
.. nonce: _mzXJW
.. section: Library

Restarting a ``ProactorEventLoop`` on Windows no longer logs spurious
``ConnectionResetErrors``.

..

.. bpo: 41638
.. date: 2020-08-29-16-45-12
.. nonce: iZfW5N
.. section: Library

:exc:`~sqlite3.ProgrammingError` message for absent parameter in
:mod:`sqlite3` contains now the name of the parameter instead of its index
when parameters are supplied as a dict.

..

.. bpo: 41662
.. date: 2020-08-29-16-07-36
.. nonce: Mn79zh
.. section: Library

Fixed crash when mutate list of parameters during iteration in
:mod:`sqlite3`.

..

.. bpo: 41513
.. date: 2020-08-23-14-23-18
.. nonce: DGqc_I
.. section: Library

Improved the accuracy of math.hypot().  Internally, each step is computed
with extra precision so that the result is now almost always correctly
rounded.

..

.. bpo: 41609
.. date: 2020-08-21-15-51-15
.. nonce: JmiUKG
.. section: Library

The pdb whatis command correctly reports instance methods as 'Method' rather
than 'Function'.

..

.. bpo: 39994
.. date: 2020-08-15-18-17-21
.. nonce: dOgPOh
.. section: Library

Fixed pprint's handling of dict subclasses that override __repr__.

..

.. bpo: 32751
.. date: 2020-08-15-15-50-12
.. nonce: 85je5X
.. section: Library

When cancelling the task due to a timeout, :meth:`asyncio.wait_for` will now
wait until the cancellation is complete also in the case when *timeout* is
<= 0, like it does with positive timeouts.

..

.. bpo: 37658
.. date: 2020-08-15-15-21-40
.. nonce: f9nivB
.. section: Library

:meth:`asyncio.wait_for` now properly handles races between cancellation of
itself and the completion of the wrapped awaitable.

..

.. bpo: 40782
.. date: 2020-08-13-08-07-25
.. nonce: aGZqmB
.. section: Library

Change the method asyncio.AbstractEventLoop.run_in_executor to not be a
coroutine.

..

.. bpo: 41520
.. date: 2020-08-12-13-25-16
.. nonce: BEUWa4
.. section: Library

Fix :mod:`codeop` regression that prevented turning compile warnings into
errors.

..

.. bpo: 41528
.. date: 2020-08-12-07-43-31
.. nonce: bu83oD
.. section: Library

turtle uses math module functions to convert degrees to radians and vice
versa and to calculate vector norm

..

.. bpo: 41513
.. date: 2020-08-09-18-16-05
.. nonce: e6K6EK
.. section: Library

Minor algorithmic improvement to math.hypot() and math.dist() giving small
gains in speed and accuracy.

..

.. bpo: 41503
.. date: 2020-08-07-15-18-16
.. nonce: IYftcu
.. section: Library

Fixed a race between setTarget and flush in logging.handlers.MemoryHandler.

..

.. bpo: 41497
.. date: 2020-08-07-06-06-29
.. nonce: aBtsWz
.. section: Library

Fix potential UnicodeDecodeError in dis module.

..

.. bpo: 41467
.. date: 2020-08-04-00-20-30
.. nonce: Z8DgTL
.. section: Library

On Windows, fix asyncio ``recv_into()`` return value when the socket/pipe is
closed (:exc:`BrokenPipeError`): return ``0`` rather than an empty byte
string (``b''``).

..

.. bpo: 41425
.. date: 2020-08-03-01-59-48
.. nonce: KJo6zF
.. section: Library

Make tkinter doc example runnable.

..

.. bpo: 41421
.. date: 2020-08-01-00-51-15
.. nonce: dHKRVB
.. section: Library

Make an algebraic simplification to random.paretovariate().  It now is
slightly less subject to round-off error and is slightly faster. Inputs that
used to cause ZeroDivisionError now cause an OverflowError instead.

..

.. bpo: 41440
.. date: 2020-07-30-14-56-58
.. nonce: rju34k
.. section: Library

Add :func:`os.cpu_count()` support for VxWorks RTOS.

..

.. bpo: 41316
.. date: 2020-07-28-12-08-58
.. nonce: bSCbK4
.. section: Library

Fix the :mod:`tarfile` module to write only basename of TAR file to GZIP
compression header.

..

.. bpo: 41384
.. date: 2020-07-26-21-18-43
.. nonce: MlzIgV
.. section: Library

Raise TclError instead of TypeError when an unknown option is passed to
tkinter.OptionMenu.

..

.. bpo: 41317
.. date: 2020-07-23-01-18-34
.. nonce: O17Z6x
.. section: Library

Use add_done_callback() in asyncio.loop.sock_accept() to unsubscribe reader
early on cancellation.

..

.. bpo: 41364
.. date: 2020-07-21-21-45-55
.. nonce: 5O-k7A
.. section: Library

Reduce import overhead of :mod:`uuid`.

..

.. bpo: 35328
.. date: 2020-07-21-16-20-55
.. nonce: jXovHb
.. section: Library

Set the environment variable ``VIRTUAL_ENV_PROMPT`` at :mod:`venv`
activation.

..

.. bpo: 41341
.. date: 2020-07-20-19-13-17
.. nonce: wqrj8C
.. section: Library

Recursive evaluation of ``typing.ForwardRef`` in ``get_type_hints``.

..

.. bpo: 41344
.. date: 2020-07-20-13-27-48
.. nonce: iKipNd
.. section: Library

Prevent creating :class:`shared_memory.SharedMemory` objects with
:code:`size=0`.

..

.. bpo: 41333
.. date: 2020-07-18-18-07-40
.. nonce: upkHIm
.. section: Library

:meth:`collections.OrderedDict.pop` is now 2 times faster.

..

.. bpo: 41288
.. date: 2020-07-13-15-06-35
.. nonce: 8mn5P-
.. section: Library

Unpickling invalid NEWOBJ_EX opcode with the C implementation raises now
UnpicklingError instead of crashing.

..

.. bpo: 39017
.. date: 2020-07-12-22-16-58
.. nonce: x3Cg-9
.. section: Library

Avoid infinite loop when reading specially crafted TAR files using the
tarfile module (:cve:`2019-20907`).

..

.. bpo: 41273
.. date: 2020-07-11-00-15-01
.. nonce: SVrsJh
.. section: Library

Speed up any transport using ``_ProactorReadPipeTransport`` by calling
``recv_into`` instead of ``recv``, thus not creating a new buffer for each
``recv`` call in the transport's read loop.

..

.. bpo: 41235
.. date: 2020-07-07-21-56-26
.. nonce: H2csMU
.. section: Library

Fix the error handling in :meth:`ssl.SSLContext.load_dh_params`.

..

.. bpo: 41207
.. date: 2020-07-06-16-58-53
.. nonce: Emw7Nk
.. section: Library

In distutils.spawn, restore expectation that DistutilsExecError is raised
when the command is not found.

..

.. bpo: 29727
.. date: 2020-07-05-19-16-02
.. nonce: Q6Z2rg
.. section: Library

Register :class:`array.array` as a
:class:`~collections.abc.MutableSequence`. Patch by Pablo Galindo.

..

.. bpo: 39168
.. date: 2020-07-04-21-56-46
.. nonce: DQWsXj
.. section: Library

Remove the ``__new__`` method of :class:`typing.Generic`.

..

.. bpo: 41194
.. date: 2020-07-03-13-15-08
.. nonce: djrKjs
.. section: Library

Fix a crash in the ``_ast`` module: it can no longer be loaded more than
once. It now uses a global state rather than a module state.

..

.. bpo: 41195
.. date: 2020-07-02-15-03-04
.. nonce: cEnpO3
.. section: Library

Add read-only ssl.SSLContext.security_level attribute to retrieve the
context's security level.

..

.. bpo: 41193
.. date: 2020-07-02-11-53-45
.. nonce: 8-Tnql
.. section: Library

The ``write_history()`` atexit function of the readline completer now
ignores any :exc:`OSError` to ignore error if the filesystem is read-only,
instead of only ignoring :exc:`FileNotFoundError` and
:exc:`PermissionError`.

..

.. bpo: 41182
.. date: 2020-07-01-17-33-50
.. nonce: FPFI0N
.. section: Library

selector: use DefaultSelector based upon implementation

..

.. bpo: 41161
.. date: 2020-06-30-20-50-51
.. nonce: QTdJjz
.. section: Library

The decimal module now requires libmpdec-2.5.0. Users of
--with-system-libmpdec should update their system library.

..

.. bpo: 40874
.. date: 2020-06-28-21-16-51
.. nonce: YImvzA
.. section: Library

The decimal module now requires libmpdec-2.5.0.

..

.. bpo: 41138
.. date: 2020-06-27-13-51-36
.. nonce: bIpf7g
.. section: Library

Fixed the :mod:`trace` module CLI for Python source files with non-UTF-8
encoding.

..

.. bpo: 31082
.. date: 2020-06-25-10-11-47
.. nonce: HsgDkx
.. section: Library

Use the term "iterable" in the docstring for :func:`functools.reduce`.

..

.. bpo: 40521
.. date: 2020-06-23-06-09-59
.. nonce: HUfxP7
.. section: Library

Remove freelist from collections.deque().

..

.. bpo: 31938
.. date: 2020-06-22-20-08-40
.. nonce: EVuko9
.. section: Library

Fix default-value signatures of several functions in the :mod:`select`
module - by Anthony Sottile.

..

.. bpo: 41068
.. date: 2020-06-22-10-25-39
.. nonce: _bX2BW
.. section: Library

Fixed reading files with non-ASCII names from ZIP archive directly after
writing them.

..

.. bpo: 41058
.. date: 2020-06-20-21-03-55
.. nonce: gztdZy
.. section: Library

:func:`pdb.find_function` now correctly determines the source file encoding.

..

.. bpo: 41056
.. date: 2020-06-20-18-37-29
.. nonce: d9v_uL
.. section: Library

Invalid file descriptor values are now prevented from being passed to
os.fpathconf. (discovered by Coverity)

..

.. bpo: 41056
.. date: 2020-06-20-18-35-43
.. nonce: Garcle
.. section: Library

Fix a NULL pointer dereference within the ssl module during a MemoryError in
the keylog callback. (discovered by Coverity)

..

.. bpo: 41056
.. date: 2020-06-20-18-33-03
.. nonce: gTH4Bq
.. section: Library

Fixed an instance where a MemoryError within the zoneinfo module might not
be reported or not reported at its source. (found by Coverity)

..

.. bpo: 41048
.. date: 2020-06-20-10-16-57
.. nonce: hEXB-B
.. section: Library

:func:`mimetypes.read_mime_types` function reads the rule file using UTF-8
encoding, not the locale encoding. Patch by Srinivas Reddy Thatiparthy.

..

.. bpo: 41043
.. date: 2020-06-20-00-19-30
.. nonce: p-Pk-H
.. section: Library

Fixed the use of :func:`~glob.glob` in the stdlib: literal part of the path
is now always correctly escaped.

..

.. bpo: 41025
.. date: 2020-06-18-10-34-59
.. nonce: elf_nz
.. section: Library

Fixed an issue preventing the C implementation of :class:`zoneinfo.ZoneInfo`
from being subclassed.

..

.. bpo: 35018
.. date: 2020-06-17-23-49-45
.. nonce: NP5_Qk
.. section: Library

Add the :class:`xml.sax.handler.LexicalHandler` class that is present in
other SAX XML implementations.

..

.. bpo: 41002
.. date: 2020-06-17-17-26-24
.. nonce: NPBItE
.. section: Library

Improve performance of HTTPResponse.read with a given amount. Patch by Bruce
Merry.

..

.. bpo: 40448
.. date: 2020-06-15-12-22-53
.. nonce: 1dk8Bu
.. section: Library

:mod:`ensurepip` now disables the use of ``pip`` cache when installing the
bundled versions of ``pip`` and ``setuptools``.  Patch by Krzysztof Konopko.

..

.. bpo: 40967
.. date: 2020-06-15-00-13-57
.. nonce: _dx3OO
.. section: Library

Removed :meth:`!asyncio.Task.current_task` and
:meth:`!asyncio.Task.all_tasks`. Patch contributed by Rémi Lapeyre.

..

.. bpo: 40924
.. date: 2020-06-13-12-04-50
.. nonce: SM_luS
.. section: Library

Ensure ``importlib.resources.path`` returns an extant path for the
SourceFileLoader's resource reader. Avoids the regression identified in
master while a long-term solution is devised.

..

.. bpo: 40955
.. date: 2020-06-12-11-55-30
.. nonce: huixCg
.. section: Library

Fix a minor memory leak in :mod:`subprocess` module when extra_groups was
specified.

..

.. bpo: 40855
.. date: 2020-06-12-10-44-15
.. nonce: jSot83
.. section: Library

The standard deviation and variance functions in the statistics module were
ignoring their mu and xbar arguments.

..

.. bpo: 40939
.. date: 2020-06-11-11-07-10
.. nonce: -D5Asl
.. section: Library

Use the new PEG parser when generating the stdlib :mod:`keyword` module.

..

.. bpo: 23427
.. date: 2020-06-08-18-59-16
.. nonce: ilg1Cz
.. section: Library

Add :data:`sys.orig_argv` attribute: the list of the original command line
arguments passed to the Python executable.

..

.. bpo: 33689
.. date: 2020-06-06-14-09-55
.. nonce: EFUDH7
.. section: Library

Ignore empty or whitespace-only lines in .pth files. This matches the
documentated behavior. Before, empty lines caused the site-packages dir to
appear multiple times in sys.path. By Ido Michael, contributors Malcolm
Smith and Tal Einat.

..

.. bpo: 40884
.. date: 2020-06-06-02-42-26
.. nonce: n7fOwS
.. section: Library

Added a ``defaults`` parameter to :class:`logging.Formatter`, to allow
specifying default values for custom fields. Patch by Asaf Alon and Bar
Harel.

..

.. bpo: 40876
.. date: 2020-06-05-20-00-18
.. nonce: zDhiZj
.. section: Library

Clarify error message in the :mod:`csv` module.

..

.. bpo: 39791
.. date: 2020-06-05-19-29-10
.. nonce: _CcO3d
.. section: Library

Refresh importlib.metadata from importlib_metadata 1.6.1.

..

.. bpo: 40807
.. date: 2020-06-04-16-25-15
.. nonce: yYyLWx
.. section: Library

Stop codeop._maybe_compile, used by code.InteractiveInterpreter (and IDLE).
from emitting each warning three times.

..

.. bpo: 32604
.. date: 2020-06-02-23-49-07
.. nonce: ZN4V4l
.. section: Library

Fix reference leak in the :mod:`select` module when the module is imported
in a subinterpreter.

..

.. bpo: 39791
.. date: 2020-06-02-02-16-02
.. nonce: StCJlA
.. section: Library

Built-in loaders (SourceFileLoader and ZipImporter) now supply
``TraversableResources`` implementations for ``ResourceReader``, and the
fallback function has been removed.

..

.. bpo: 39314
.. date: 2020-06-01-02-16-29
.. nonce: 0T9hlA
.. section: Library

:class:`rlcompleter.Completer` and the standard Python shell now close the
parenthesis for functions that take no arguments. Patch contributed by Rémi
Lapeyre.

..

.. bpo: 17005
.. date: 2020-05-31-23-32-36
.. nonce: JlRUGB
.. section: Library

The topological sort functionality that was introduced initially in the
:mod:`functools` module has been moved to a new :mod:`graphlib` module to
better accommodate the new tools and keep the original scope of the
:mod:`functools` module. Patch by Pablo Galindo

..

.. bpo: 40834
.. date: 2020-05-31-15-52-18
.. nonce: MO9_hb
.. section: Library

Fix truncate when sending str object with_xxsubinterpreters.channel_send.

..

.. bpo: 40755
.. date: 2020-05-30-18-48-58
.. nonce: IyOe2J
.. section: Library

Add rich comparisons to collections.Counter().

..

.. bpo: 26407
.. date: 2020-05-30-14-19-47
.. nonce: MjWLO1
.. section: Library

Unexpected errors in calling the ``__iter__`` method are no longer masked by
``TypeError`` in :func:`csv.reader`, :func:`csv.writer.writerow` and
:meth:`csv.writer.writerows`.

..

.. bpo: 39384
.. date: 2020-05-30-12-44-29
.. nonce: Iqxy3q
.. section: Library

Fixed email.contentmanager to allow set_content() to set a null string.

..

.. bpo: 40744
.. date: 2020-05-30-08-10-23
.. nonce: jKURVV
.. section: Library

The :mod:`sqlite3` module uses SQLite API functions that require SQLite
v3.7.3 or higher.  This patch removes support for older SQLite versions, and
explicitly requires SQLite 3.7.3 both at build, compile and runtime.  Patch
by Sergey Fedoseev and Erlend E. Aasland.

..

.. bpo: 40777
.. date: 2020-05-28-17-32-29
.. nonce: 1kJU6N
.. section: Library

Initialize PyDateTime_IsoCalendarDateType.tp_base at run-time to avoid
errors on some compilers.

..

.. bpo: 38488
.. date: 2020-05-28-16-51-00
.. nonce: hFQNgA
.. section: Library

Update ensurepip to install pip 20.1.1 and setuptools 47.1.0.

..

.. bpo: 40792
.. date: 2020-05-27-22-19-42
.. nonce: 87Yx01
.. section: Library

The result of :func:`operator.index` now always has exact type :class:`int`.
Previously, the result could have been an instance of a subclass of ``int``.

..

.. bpo: 40767
.. date: 2020-05-27-21-27-01
.. nonce: L5MnVV
.. section: Library

:mod:`webbrowser` now properly finds the default browser in pure Wayland
systems by checking the WAYLAND_DISPLAY environment variable. Patch
contributed by Jérémy Attali.

..

.. bpo: 40791
.. date: 2020-05-27-18-04-52
.. nonce: IzpNor
.. section: Library

:func:`hashlib.compare_digest` uses OpenSSL's ``CRYPTO_memcmp()`` function
when OpenSSL is available.

..

.. bpo: 40795
.. date: 2020-05-27-17-00-18
.. nonce: eZSnHA
.. section: Library

:mod:`ctypes` module: If ctypes fails to convert the result of a callback or
if a ctypes callback function raises an exception, sys.unraisablehook is now
called with an exception set. Previously, the error was logged into stderr
by :c:func:`PyErr_Print`.

..

.. bpo: 16995
.. date: 2020-05-27-00-09-52
.. nonce: 4niOT7
.. section: Library

Add :func:`base64.b32hexencode` and :func:`base64.b32hexdecode` to support
the Base32 Encoding with Extended Hex Alphabet.

..

.. bpo: 30008
.. date: 2020-05-25-22-18-38
.. nonce: CKC3td
.. section: Library

Fix :mod:`ssl` code to be compatible with OpenSSL 1.1.x builds that use
``no-deprecated`` and ``--api=1.1.0``.

..

.. bpo: 30064
.. date: 2020-05-25-11-52-23
.. nonce: 6CICsH
.. section: Library

Fix asyncio ``loop.sock_*`` race condition issue

..

.. bpo: 40759
.. date: 2020-05-24-23-52-35
.. nonce: DdZdaw
.. section: Library

Deprecate the :mod:`symbol` module.

..

.. bpo: 40756
.. date: 2020-05-24-11-06-37
.. nonce: 7ZH83z
.. section: Library

The second argument (extra) of ``LoggerAdapter.__init__`` now defaults to
None.

..

.. bpo: 37129
.. date: 2020-05-23-04-18-00
.. nonce: YoYoYo
.. section: Library

Add a new :const:`os.RWF_APPEND` flag for :func:`os.pwritev`.

..

.. bpo: 40737
.. date: 2020-05-23-00-22-11
.. nonce: iph-CM
.. section: Library

Fix possible reference leak for :mod:`sqlite3` initialization.

..

.. bpo: 40726
.. date: 2020-05-22-12-45-58
.. nonce: 7oBdMw
.. section: Library

Handle cases where the ``end_lineno`` is ``None`` on
:func:`ast.increment_lineno`.

..

.. bpo: 40698
.. date: 2020-05-20-14-38-04
.. nonce: zwl5Hc
.. section: Library

``distutils`` upload creates SHA2-256 and Blake2b-256 digests. MD5
digests is skipped if platform blocks MD5.

..

.. bpo: 40695
.. date: 2020-05-20-13-03-28
.. nonce: lr4aIS
.. section: Library

:mod:`hashlib` no longer falls back to builtin hash implementations when
OpenSSL provides a hash digest and the algorithm is blocked by security
policy.

..

.. bpo: 9216
.. date: 2020-05-20-12-53-20
.. nonce: ps7Yf1
.. section: Library

:func:`hashlib.new` passed ``usedforsecurity`` to OpenSSL EVP constructor
``_hashlib.new()``. test_hashlib and test_smtplib handle strict security
policy better.

..

.. bpo: 40614
.. date: 2020-05-18-22-41-02
.. nonce: 8j3kmq
.. section: Library

:func:`ast.parse` will not parse self documenting expressions in f-strings
when passed ``feature_version`` is less than ``(3, 8)``.

..

.. bpo: 40626
.. date: 2020-05-18-17-29-30
.. nonce: NeZufF
.. section: Library

Add h5 file extension as MIME Type application/x-hdf5, as per HDF Group
recommendation for HDF5 formatted data files. Patch contributed by Mark
Schwab.

..

.. bpo: 25920
.. date: 2020-05-18-15-38-25
.. nonce: PxrLY8
.. section: Library

On macOS, when building Python for macOS 10.4 and older, which wasn't the
case for python.org macOS installer, :func:`socket.getaddrinfo` no longer
uses an internal lock to prevent race conditions when calling
``getaddrinfo()`` which is thread-safe since macOS 10.5. Python 3.9 requires
macOS 10.6 or newer. The internal lock caused random hang on fork when
another thread was calling :func:`socket.getaddrinfo`. The lock was also
used on FreeBSD older than 5.3, OpenBSD older than 201311 and NetBSD older
than 4.

..

.. bpo: 40671
.. date: 2020-05-18-15-26-31
.. nonce: NeZ9Cy
.. section: Library

Prepare ``_hashlib`` for :pep:`489` and use :c:func:`PyModule_AddType`.

..

.. bpo: 32309
.. date: 2020-05-17-02-03-09
.. nonce: KM9psl
.. section: Library

Added a new :term:`coroutine` :func:`asyncio.to_thread`. It is mainly used
for running IO-bound functions in a separate thread to avoid blocking the
event loop, and essentially works as a high-level version of
:meth:`~asyncio.loop.run_in_executor` that can directly take keyword
arguments.

..

.. bpo: 36543
.. date: 2020-05-15-21-14-45
.. nonce: Jt-eSX
.. section: Library

Restored the deprecated :mod:`xml.etree.cElementTree` module.

..

.. bpo: 40611
.. date: 2020-05-13-16-28-33
.. nonce: ZCk0_c
.. section: Library

:const:`~mmap.MAP_POPULATE` constant has now been added to the list of
exported :mod:`mmap` module flags.

..

.. bpo: 39881
.. date: 2020-05-07-22-00-12
.. nonce: E1xsNv
.. section: Library

PEP 554 for use in the test suite. (Patch By Joannah Nanjekye)

..

.. bpo: 13097
.. date: 2020-05-06-02-01-25
.. nonce: Wh5xSK
.. section: Library

``ctypes`` now raises an ``ArgumentError`` when a callback is invoked with
more than 1024 arguments.

..

.. bpo: 39385
.. date: 2020-04-23-18-21-19
.. nonce: MIAyS7
.. section: Library

A new test assertion context-manager, :func:`unittest.assertNoLogs` will
ensure a given block of code emits no log messages using the logging module.
Contributed by Kit Yan Choi.

..

.. bpo: 23082
.. date: 2020-04-20-22-08-36
.. nonce: iX90Id
.. section: Library

Updated the error message and docs of PurePath.relative_to() to better
reflect the function behaviour.

..

.. bpo: 40318
.. date: 2020-04-18-14-16-02
.. nonce: K2UdRx
.. section: Library

Use SQLite3 trace v2 API, if it is available.

..

.. bpo: 40105
.. date: 2020-04-03-16-13-59
.. nonce: hfM2c0
.. section: Library

ZipFile truncates files to avoid corruption when a shorter comment is
provided in append ("a") mode. Patch by Jan Mazur.

..

.. bpo: 40084
.. date: 2020-03-29-21-32-00
.. nonce: MCYwcv
.. section: Library

Fix ``Enum.__dir__``: dir(Enum.member) now includes attributes as well as
methods.

..

.. bpo: 31122
.. date: 2020-03-11-07-44-06
.. nonce: zIQ80l
.. section: Library

ssl.wrap_socket() now raises ssl.SSLEOFError rather than OSError when peer
closes connection during TLS negotiation

..

.. bpo: 39728
.. date: 2020-02-24-10-58-34
.. nonce: kOOaHn
.. section: Library

fix default ``_missing_`` so a duplicate ``ValueError`` is not set as the
``__context__`` of the original ``ValueError``.

..

.. bpo: 39244
.. date: 2020-02-23-15-09-47
.. nonce: aBK5IM
.. section: Library

Fixed :class:`multiprocessing.context.get_all_start_methods` to properly
return the default method first on macOS.

..

.. bpo: 39040
.. date: 2019-12-15-18-47-20
.. nonce: tKa0Qs
.. section: Library

Fix parsing of invalid mime headers parameters by collapsing whitespace
between encoded words in a bare-quote-string.

..

.. bpo: 38731
.. date: 2019-11-13-07-37-11
.. nonce: 9qmcSx
.. section: Library

Add ``--quiet`` option to command-line interface of :mod:`py_compile`. Patch
by Gregory Schevchenko.

..

.. bpo: 35714
.. date: 2019-10-25-23-45-49
.. nonce: fw3xb7
.. section: Library

:exc:`struct.error` is now raised if there is a null character in a
:mod:`struct` format string.

..

.. bpo: 38144
.. date: 2019-09-12-21-34-03
.. nonce: 8uQCdd
.. section: Library

Added the *root_dir* and *dir_fd* parameters in :func:`glob.glob`.

..

.. bpo: 26543
.. date: 2019-08-11-16-28-03
.. nonce: X-TJZO
.. section: Library

Fix :meth:`IMAP4.noop()` when debug mode is enabled (ex: ``imaplib.Debug =
3``).

..

.. bpo: 12178
.. date: 2019-05-31-23-54-28
.. nonce: N6FLCZ
.. section: Library

:func:`csv.writer` now correctly escapes *escapechar* when input contains
*escapechar*.  Patch by Catalin Iacob, Berker Peksag, and Itay Elbirt.

..

.. bpo: 36290
.. date: 2019-03-17-19-01-53
.. nonce: 7VXo_K
.. section: Library

AST nodes are now raising :exc:`TypeError` on conflicting keyword arguments.
Patch contributed by Rémi Lapeyre.

..

.. bpo: 33944
.. date: 2019-03-01-01-56-23
.. nonce: -82Pkt
.. section: Library

Added site.py site-packages tracing in verbose mode.

..

.. bpo: 35078
.. date: 2018-10-27-09-37-03
.. nonce: kweA3R
.. section: Library

Refactor formatweekday, formatmonthname methods in LocaleHTMLCalendar and
LocaleTextCalendar classes in calendar module to call the base class
methods.This enables customizable CSS classes for LocaleHTMLCalendar. Patch
by Srinivas Reddy Thatiparthy

..

.. bpo: 29620
.. date: 2018-08-21-16-20-33
.. nonce: xxx666
.. section: Library

:func:`~unittest.TestCase.assertWarns` no longer raises a
``RuntimeException`` when accessing a module's ``__warningregistry__``
causes importation of a new module, or when a new module is imported in
another thread. Patch by Kernc.

..

.. bpo: 31844
.. date: 2018-07-30-12-48-17
.. nonce: 0_GKsD
.. section: Library

Remove ``ParserBase.error()`` method from the private and undocumented
``_markupbase`` module.  :class:`html.parser.HTMLParser` is the only
subclass of ``ParserBase`` and its ``error()`` implementation was deprecated
in Python 3.4 and removed in Python 3.5.

..

.. bpo: 34226
.. date: 2018-07-29-12-14-54
.. nonce: BE7zbu
.. section: Library

Fix ``cgi.parse_multipart`` without content_length. Patch by Roger Duran

..

.. bpo: 33660
.. date: 2018-06-12-23-30-41
.. nonce: AdDn5Z
.. section: Library

Fix pathlib.PosixPath to resolve a relative path located on the root
directory properly.

..

.. bpo: 28557
.. date: 2018-06-07-22-04-01
.. nonce: ViNJnK
.. section: Library

Improve the error message for a misbehaving ``rawio.readinto``

..

.. bpo: 26680
.. date: 2018-03-15-11-56-48
.. nonce: Udkhn4
.. section: Library

The d.is_integer() method is added to the Decimal type, for compatibility
with other number types.

..

.. bpo: 26680
.. date: 2018-03-15-11-55-04
.. nonce: eKAi85
.. section: Library

The x.is_integer() method is incorporated into the abstract types of the
numeric tower, Real, Rational and Integral, with appropriate default
implementations.

..

.. bpo: 41428
.. date: 2020-10-03-18-20-46
.. nonce: _ju1NE
.. section: Documentation

Add documentation for :pep:`604` (Allow writing union types as ``X | Y``).

..

.. bpo: 41774
.. date: 2020-09-24-15-35-13
.. nonce: 5IqdGP
.. section: Documentation

In Programming FAQ "Sequences (Tuples/Lists)" section, add "How do you
remove multiple items from a list".

..

.. bpo: 35293
.. date: 2020-09-12-17-37-13
.. nonce: _cOwPD
.. section: Documentation

Fix RemovedInSphinx40Warning when building the documentation. Patch by
Donghee Na.

..

.. bpo: 37149
.. date: 2020-09-10-07-48-02
.. nonce: VD0rCv
.. section: Documentation

Change Shipman tkinter doc link from archive.org to TkDocs. (The doc has
been removed from the NMT server.)  The new link responds much faster and
includes a short explanatory note.

..

.. bpo: 41726
.. date: 2020-09-08-16-57-09
.. nonce: g0UXrn
.. section: Documentation

Update the refcounts info of ``PyType_FromModuleAndSpec``.

..

.. bpo: 41624
.. date: 2020-08-25-15-11-23
.. nonce: ddjJlN
.. section: Documentation

Fix the signature of :class:`typing.Coroutine`.

..

.. bpo: 40204
.. date: 2020-08-12-18-35-40
.. nonce: C8A_pe
.. section: Documentation

Enable Sphinx 3.2 ``c_allow_pre_v3`` option and disable
``c_warn_on_allowed_pre_v3`` option to make the documentation compatible
with Sphinx 2 and Sphinx 3.

..

.. bpo: 41045
.. date: 2020-07-27-20-46-17
.. nonce: GFF6Ul
.. section: Documentation

Add documentation for debug feature of f-strings.

..

.. bpo: 41314
.. date: 2020-07-25-14-20-00
.. nonce: yrjko0
.. section: Documentation

Changed the release when ``from __future__ import annotations`` becomes the
default from ``4.0`` to ``3.10`` (following a change in PEP 563).

..

.. bpo: 40979
.. date: 2020-07-21-15-23-30
.. nonce: pLA8rO
.. section: Documentation

Refactored typing.rst, arranging more than 70 classes, functions, and
decorators into new sub-sections.

..

.. bpo: 40552
.. date: 2020-05-09-12-10-31
.. nonce: _0uB73
.. section: Documentation

Fix in tutorial section 4.2. Code snippet is now correct.

..

.. bpo: 39883
.. date: 2020-03-07-03-53-39
.. nonce: 1tnb4-
.. section: Documentation

Make code, examples, and recipes in the Python documentation be licensed
under the more permissive BSD0 license in addition to the existing Python
2.0 license.

..

.. bpo: 37703
.. date: 2019-08-16-20-25-42
.. nonce: Qm_l_H
.. section: Documentation

Updated Documentation to comprehensively elaborate on the behaviour of
gather.cancel()

..

.. bpo: 41939
.. date: 2020-10-05-09-37-43
.. nonce: P4OlbA
.. section: Tests

Fix test_site.test_license_exists_at_url(): call
``urllib.request.urlcleanup()`` to reset the global
``urllib.request._opener``. Patch by Victor Stinner.

..

.. bpo: 41731
.. date: 2020-09-11-19-12-31
.. nonce: Ivxh4U
.. section: Tests

Make test_cmd_line_script pass with option '-vv'.

..

.. bpo: 41602
.. date: 2020-08-25-19-25-36
.. nonce: Z64s0I
.. section: Tests

Add tests for SIGINT handling in the runpy module.

..

.. bpo: 41521
.. date: 2020-08-11-14-59-13
.. nonce: w2UYK7
.. section: Tests

:mod:`test.support`: Rename ``blacklist`` parameter of
:func:`~test.support.check__all__` to ``not_exported``.

..

.. bpo: 41477
.. date: 2020-08-07-17-28-49
.. nonce: GrFexU
.. section: Tests

Make ctypes optional in test_genericalias.

..

.. bpo: 41085
.. date: 2020-06-23-12-02-45
.. nonce: JZKsyz
.. section: Tests

Fix integer overflow in the :meth:`array.array.index` method on 64-bit
Windows for index larger than ``2**31``.

..

.. bpo: 41069
.. date: 2020-06-22-00-21-12
.. nonce: bLZkX-
.. section: Tests

:data:`test.support.TESTFN` and the current directory for tests when run via
``test.regrtest`` contain now non-ascii characters if possible.

..

.. bpo: 38377
.. date: 2020-06-17-18-00-21
.. nonce: jfg4TH
.. section: Tests

On Linux, skip tests using multiprocessing if the current user cannot create
a file in ``/dev/shm/`` directory. Add the
:func:`~test.support.skip_if_broken_multiprocessing_synchronize` function to
the :mod:`test.support` module.

..

.. bpo: 41009
.. date: 2020-06-17-17-27-07
.. nonce: Rvn6OQ
.. section: Tests

Fix use of ``support.require_{linux|mac|freebsd}_version()`` decorators as
class decorator.

..

.. bpo: 41003
.. date: 2020-06-17-15-07-14
.. nonce: tiH_Fy
.. section: Tests

Fix ``test_copyreg`` when ``numpy`` is installed: ``test.pickletester`` now
saves/restores warnings filters when importing ``numpy``, to ignore filters
installed by ``numpy``.

..

.. bpo: 40964
.. date: 2020-06-12-20-46-23
.. nonce: OBzf2c
.. section: Tests

Disable remote :mod:`imaplib` tests, host cyrus.andrew.cmu.edu is blocking
incoming connections.

..

.. bpo: 40927
.. date: 2020-06-09-18-48-18
.. nonce: 67ylLg
.. section: Tests

Fix test_binhex when run twice: it now uses import_fresh_module() to ensure
that it raises DeprecationWarning each time.

..

.. bpo: 17258
.. date: 2020-05-26-07-53-31
.. nonce: X_IKTQ
.. section: Tests

Skip some :mod:`multiprocessing` tests when MD5 hash digest is blocked.

..

.. bpo: 31904
.. date: 2020-04-09-15-40-03
.. nonce: TJ4k3d
.. section: Tests

Increase LOOPBACK_TIMEOUT to 10 for VxWorks RTOS.

..

.. bpo: 38169
.. date: 2019-09-14-13-20-27
.. nonce: hurq4B
.. section: Tests

Increase code coverage for SharedMemory and ShareableList

..

.. bpo: 34401
.. date: 2018-08-20-09-38-52
.. nonce: eGxMPm
.. section: Tests

Make test_gdb properly run on HP-UX. Patch by Michael Osipov.

..

.. bpo: 38249
.. date: 2020-09-28-21-56-51
.. nonce: uzMCaZ
.. section: Build

Update :c:macro:`Py_UNREACHABLE` to use __builtin_unreachable() if only the
compiler is able to use it. Patch by Donghee Na.

..

.. bpo: 41617
.. date: 2020-08-24-18-34-01
.. nonce: sKKXz7
.. section: Build

Fix ``pycore_bitutils.h`` header file to support old clang versions:
``__builtin_bswap16()`` is not available in LLVM clang 3.0.

..

.. bpo: 40204
.. date: 2020-06-25-06-59-13
.. nonce: GpD04D
.. section: Build

Pin Sphinx version to 2.3.1 in ``Doc/Makefile``.

..

.. bpo: 36020
.. date: 2020-06-15-22-14-25
.. nonce: wbiv0P
.. section: Build

The C99 functions :c:func:`snprintf` and :c:func:`vsnprintf` are now
required to build Python.

..

.. bpo: 40684
.. date: 2020-06-08-19-57-05
.. nonce: WIY2-i
.. section: Build

``make install`` now uses the ``PLATLIBDIR`` variable for the destination
``lib-dynload/`` directory when ``./configure --with-platlibdir`` is used.

..

.. bpo: 40683
.. date: 2020-05-19-10-54-08
.. nonce: W8JHrr
.. section: Build

Fixed an issue where the :mod:`zoneinfo` module and its tests were not
included when Python is installed with ``make``.

..

.. bpo: 41744
.. date: 2020-09-11-17-59-33
.. nonce: e_ugDQ
.. section: Windows

Fixes automatic import of props file when using the Nuget package.

..

.. bpo: 41627
.. date: 2020-09-04-21-35-28
.. nonce: sx2KN1
.. section: Windows

The user site directory for 32-bit now includes a ``-32`` suffix to
distinguish it from the 64-bit interpreter's directory.

..

.. bpo: 41526
.. date: 2020-08-13-22-40-58
.. nonce: -i2bwb
.. section: Windows

Fixed layout of final page of the installer by removing the special thanks
to Mark Hammond (with his permission).

..

.. bpo: 41492
.. date: 2020-08-06-16-59-10
.. nonce: 2FQ9cM
.. section: Windows

Fixes the description that appears in UAC prompts.

..

.. bpo: 40948
.. date: 2020-07-28-12-39-32
.. nonce: ISUFO6
.. section: Windows

Improve post-install message to direct people to the "py" command.

..

.. bpo: 41412
.. date: 2020-07-28-11-55-43
.. nonce: ME20KB
.. section: Windows

The installer will now fail to install on Windows 7 and Windows 8. Further,
the UCRT dependency is now always downloaded on demand.

..

.. bpo: 40741
.. date: 2020-07-20-23-26-26
.. nonce: C9sc_d
.. section: Windows

Update Windows release to include SQLite 3.32.3.

..

.. bpo: 41142
.. date: 2020-06-28-12-40-41
.. nonce: jpZzzh
.. section: Windows

:mod:`!msilib` now supports creating CAB files with non-ASCII file path and
adding files with non-ASCII file path to them.

..

.. bpo: 41074
.. date: 2020-06-24-21-30-42
.. nonce: gaQc3C
.. section: Windows

Fixed support of non-ASCII names in functions :func:`!msilib.OpenDatabase`
and :func:`!msilib.init_database` and non-ASCII SQL in method
:meth:`!msilib.Database.OpenView`.

..

.. bpo: 41039
.. date: 2020-06-23-03-12-57
.. nonce: 0hgd0s
.. section: Windows

Stable ABI redirection DLL (python3.dll) now uses ``#pragma
comment(linker)`` for re-exporting.

..

.. bpo: 40164
.. date: 2020-06-12-13-13-44
.. nonce: SPrSn5
.. section: Windows

Updates Windows OpenSSL to 1.1.1g

..

.. bpo: 39631
.. date: 2020-05-19-14-43-33
.. nonce: Z5yXam
.. section: Windows

Changes the registered MIME type for ``.py`` files on Windows to
``text/x-python`` instead of ``text/plain``.

..

.. bpo: 40677
.. date: 2020-05-19-04-11-12
.. nonce: qQbLW8
.. section: Windows

Manually define IO_REPARSE_TAG_APPEXECLINK in case some old Windows SDK
doesn't have it.

..

.. bpo: 37556
.. date: 2019-07-11-06-11-09
.. nonce: sygMUU
.. section: Windows

Extend py.exe help to mention overrides via venv, shebang, environmental
variables & ini files.

..

.. bpo: 41557
.. date: 2020-08-26-09-31-37
.. nonce: mcQ75z
.. section: macOS

Update macOS installer to use SQLite 3.33.0.

..

.. bpo: 39580
.. date: 2020-06-25-06-09-00
.. nonce: N_vJ9h
.. section: macOS

Avoid opening Finder window if running installer from the command line.
Patch contributed by Rick Heil.

..

.. bpo: 41100
.. date: 2020-06-24-13-51-57
.. nonce: mcHdc5
.. section: macOS

Fix configure error when building on macOS 11. Note that the current Python
release was released shortly after the first developer preview of macOS 11
(Big Sur); there are other known issues with building and running on the
developer preview. Big Sur is expected to be fully supported in a future
bugfix release of Python 3.8.x and with 3.9.0.

..

.. bpo: 40741
.. date: 2020-06-19-14-19-08
.. nonce: L7yTbm
.. section: macOS

Update macOS installer to use SQLite 3.32.3.

..

.. bpo: 41005
.. date: 2020-06-17-13-45-15
.. nonce: zZegdV
.. section: macOS

fixed an XDG settings issue not allowing macos to open browser in
webbrowser.py

..

.. bpo: 40741
.. date: 2020-06-07-20-10-56
.. nonce: 80A2BW
.. section: macOS

Update macOS installer to use SQLite 3.32.2.

..

.. bpo: 41775
.. date: 2020-09-24-14-31-16
.. nonce: sB8Vre
.. section: IDLE

Use 'IDLE Shell' as shell title

..

.. bpo: 35764
.. date: 2020-09-22-11-13-45
.. nonce: VoNa8y
.. section: IDLE

Rewrite the Calltips doc section.

..

.. bpo: 40181
.. date: 2020-09-22-00-45-40
.. nonce: hhQi3z
.. section: IDLE

In calltips, stop reminding that '/' marks the end of positional-only
arguments.

..

.. bpo: 41468
.. date: 2020-08-09-13-42-55
.. nonce: zkP0_Y
.. section: IDLE

Improve IDLE run crash error message (which users should never see).

..

.. bpo: 41373
.. date: 2020-07-24-17-49-58
.. nonce: YQIPu_
.. section: IDLE

Save files loaded with no line ending, as when blank, or different line
endings, by setting its line ending to the system default. Fix regression in
3.8.4 and 3.9.0b4.

..

.. bpo: 41300
.. date: 2020-07-16-17-39-06
.. nonce: wRixNb
.. section: IDLE

Save files with non-ascii chars. Fix regression released in 3.9.0b4 and
3.8.4.

..

.. bpo: 37765
.. date: 2020-07-07-18-44-30
.. nonce: umc1o8
.. section: IDLE

Add keywords to module name completion list.  Rewrite Completions section of
IDLE doc.

..

.. bpo: 41152
.. date: 2020-06-29-14-51-15
.. nonce: d6mV0C
.. section: IDLE

The encoding of ``stdin``, ``stdout`` and ``stderr`` in IDLE is now always
UTF-8.

..

.. bpo: 41144
.. date: 2020-06-27-17-02-00
.. nonce: JoFGIX
.. section: IDLE

Make Open Module open a special module such as os.path.

..

.. bpo: 39885
.. date: 2020-05-29-18-21-58
.. nonce: zB_-bN
.. section: IDLE

Make context menu Cut and Copy work again when right-clicking within a
selection.

..

.. bpo: 40723
.. date: 2020-05-24-06-19-43
.. nonce: AJLd4U
.. section: IDLE

Make test_idle pass when run after import.

..

.. bpo: 41936
.. date: 2020-10-05-01-25-23
.. nonce: 1gb5ra
.. section: C API

Removed undocumented macros ``Py_ALLOW_RECURSION`` and
``Py_END_ALLOW_RECURSION`` and the ``recursion_critical`` field of the
:c:type:`PyInterpreterState` structure.

..

.. bpo: 41692
.. date: 2020-10-02-00-57-34
.. nonce: fDScsF
.. section: C API

The ``PyUnicode_InternImmortal()`` function is now deprecated and will be
removed in Python 3.12: use :c:func:`PyUnicode_InternInPlace` instead. Patch
by Victor Stinner.

..

.. bpo: 41842
.. date: 2020-09-27-20-43-16
.. nonce: bCakAj
.. section: C API

Add :c:func:`PyCodec_Unregister` function to unregister a codec search
function.

..

.. bpo: 41834
.. date: 2020-09-22-14-47-12
.. nonce: nrOrDU
.. section: C API

Remove the ``_Py_CheckRecursionLimit`` variable: it has been replaced by
``ceval.recursion_limit`` of the :c:type:`PyInterpreterState` structure.
Patch by Victor Stinner.

..

.. bpo: 41689
.. date: 2020-09-01-23-39-45
.. nonce: zxHbLB
.. section: C API

Types created with :c:func:`PyType_FromSpec` now make any signature in their
``tp_doc`` slot accessible from ``__text_signature__``.

..

.. bpo: 41524
.. date: 2020-08-12-17-09-06
.. nonce: u6Xfr2
.. section: C API

Fix bug in PyOS_mystrnicmp and PyOS_mystricmp that incremented pointers
beyond the end of a string.

..

.. bpo: 41324
.. date: 2020-08-10-16-05-08
.. nonce: waZD35
.. section: C API

Add a minimal decimal capsule API.  The API supports fast conversions
between Decimals up to 38 digits and their triple representation as a C
struct.

..

.. bpo: 30155
.. date: 2020-07-26-19-39-45
.. nonce: rHZRJ_
.. section: C API

Add :c:func:`PyDateTime_DATE_GET_TZINFO` and
:c:func:`PyDateTime_TIME_GET_TZINFO` macros for accessing the ``tzinfo``
attributes of :class:`datetime.datetime` and :class:`datetime.time` objects.

..

.. bpo: 40170
.. date: 2020-07-08-10-14-52
.. nonce: N6Qx1i
.. section: C API

Revert :c:func:`PyType_HasFeature` change: it reads again directly the
:c:member:`PyTypeObject.tp_flags` member when the limited C API is not used,
rather than always calling :c:func:`PyType_GetFlags` which hides
implementation details.

..

.. bpo: 41123
.. date: 2020-06-29-15-49-36
.. nonce: wYY4E1
.. section: C API

Remove ``PyUnicode_AsUnicodeCopy``.

..

.. bpo: 41123
.. date: 2020-06-29-11-33-49
.. nonce: qFevek
.. section: C API

Removed ``PyLong_FromUnicode()``.

..

.. bpo: 41123
.. date: 2020-06-28-11-39-22
.. nonce: sjJWjQ
.. section: C API

Removed ``PyUnicode_GetMax()``.

..

.. bpo: 41123
.. date: 2020-06-26-13-29-25
.. nonce: bRa1oy
.. section: C API

Removed ``Py_UNICODE_str*`` functions manipulating ``Py_UNICODE*`` strings.

..

.. bpo: 41103
.. date: 2020-06-24-22-57-07
.. nonce: doojgE
.. section: C API

``PyObject_AsCharBuffer()``, ``PyObject_AsReadBuffer()``,
``PyObject_CheckReadBuffer()``, and ``PyObject_AsWriteBuffer()`` are
removed. Please migrate to new buffer protocol; :c:func:`PyObject_GetBuffer`
and :c:func:`PyBuffer_Release`.

..

.. bpo: 36346
.. date: 2020-06-17-20-31-12
.. nonce: mwIyxi
.. section: C API

Raises DeprecationWarning for ``PyUnicode_FromUnicode(NULL, size)`` and
``PyUnicode_FromStringAndSize(NULL, size)`` with ``size > 0``.

..

.. bpo: 36346
.. date: 2020-06-17-11-24-00
.. nonce: fTMr3S
.. section: C API

Mark ``Py_UNICODE_COPY``, ``Py_UNICODE_FILL``, ``PyUnicode_WSTR_LENGTH``,
``PyUnicode_FromUnicode``, ``PyUnicode_AsUnicode``, and
``PyUnicode_AsUnicodeAndSize`` as deprecated in C. Remove
``Py_UNICODE_MATCH`` which was deprecated and broken since Python 3.3.

..

.. bpo: 40989
.. date: 2020-06-15-23-17-51
.. nonce: tlzG3r
.. section: C API

The :c:func:`PyObject_INIT` and :c:func:`PyObject_INIT_VAR` macros become
aliases to, respectively, :c:func:`PyObject_Init` and
:c:func:`PyObject_InitVar` functions.

..

.. bpo: 36020
.. date: 2020-06-15-16-46-01
.. nonce: djI6jw
.. section: C API

On Windows, ``#include "pyerrors.h"`` no longer defines ``snprintf`` and
``vsnprintf`` macros.

..

.. bpo: 40943
.. date: 2020-06-10-18-37-26
.. nonce: i4q7rK
.. section: C API

The ``PY_SSIZE_T_CLEAN`` macro must now be defined to use
:c:func:`PyArg_ParseTuple` and :c:func:`Py_BuildValue` formats which use
``#``: ``es#``, ``et#``, ``s#``, ``u#``, ``y#``, ``z#``, ``U#`` and ``Z#``.
See :ref:`Parsing arguments and building values <arg-parsing>` and the
:pep:`353`.

..

.. bpo: 40910
.. date: 2020-06-08-15-59-06
.. nonce: L56oI0
.. section: C API

Export explicitly the :c:func:`Py_GetArgcArgv` function to the C API and
document the function. Previously, it was exported implicitly which no
longer works since Python is built with ``-fvisibility=hidden``.

..

.. bpo: 40724
.. date: 2020-06-04-08-01-23
.. nonce: qIIdSi
.. section: C API

Allow defining buffer slots in type specs.

..

.. bpo: 40679
.. date: 2020-06-03-17-48-13
.. nonce: 3sgWma
.. section: C API

Fix a ``_PyEval_EvalCode()`` crash if *qualname* argument is NULL.

..

.. bpo: 40839
.. date: 2020-06-01-20-47-49
.. nonce: bAi52Z
.. section: C API

Calling :c:func:`PyDict_GetItem` without :term:`GIL` held had been allowed
for historical reason. It is no longer allowed.

..

.. bpo: 40826
.. date: 2020-06-01-16-12-37
.. nonce: zQzFoK
.. section: C API

:c:func:`PyOS_InterruptOccurred` now fails with a fatal error if it is
called with the GIL released.

..

.. bpo: 40792
.. date: 2020-05-27-11-02-15
.. nonce: pBw2Bb
.. section: C API

The result of :c:func:`PyNumber_Index` now always has exact type
:class:`int`. Previously, the result could have been an instance of a
subclass of ``int``.

..

.. bpo: 39573
.. date: 2020-05-26-16-21-47
.. nonce: depAgq
.. section: C API

Convert :c:func:`Py_REFCNT` and :c:func:`Py_SIZE` macros to static inline
functions. They cannot be used as l-value anymore: use
:c:func:`Py_SET_REFCNT` and :c:func:`Py_SET_SIZE` to set an object reference
count and size. This change is backward incompatible on purpose, to prepare
the C API for an opaque :c:type:`PyObject` structure.

..

.. bpo: 40703
.. date: 2020-05-20-19-11-12
.. nonce: qQXfW8
.. section: C API

The PyType_FromSpec*() functions no longer overwrite the type's "__module__"
attribute if it is set via "Py_tp_members" or "Py_tp_getset".

..

.. bpo: 39583
.. date: 2020-02-08-08-01-35
.. nonce: qURKSl
.. section: C API

Remove superfluous "extern C" declarations from ``Include/cpython/*.h``.
