Misc/NEWS.d/3.8.0b4.rst

.. bpo: 34155
.. date: 2019-05-04-13-33-37
.. nonce: MJll68
.. release date: 2019-08-29
.. section: Security

Fix parsing of invalid email addresses with more than one ``@`` (e.g.
a@b@c.com.) to not return the part before 2nd ``@`` as valid email address.
Patch by maxking & jpic.

..

.. bpo: 37947
.. date: 2019-08-26-04-09-57
.. nonce: mzAQtB
.. section: Core and Builtins

Adjust correctly the recursion level in the symtable generation for named
expressions. Patch by Pablo Galindo.

..

.. bpo: 37830
.. date: 2019-08-17-18-41-59
.. nonce: fNfMbz
.. section: Core and Builtins

Fixed compilation of :keyword:`break` and :keyword:`continue` in the
:keyword:`finally` block when the corresponding :keyword:`try` block
contains :keyword:`return` with a non-constant value.

..

.. bpo: 32912
.. date: 2019-08-06-14-03-59
.. nonce: UDwSMJ
.. section: Core and Builtins

Reverted :issue:`32912`: emitting :exc:`SyntaxWarning` instead of
:exc:`DeprecationWarning` for invalid escape sequences in string and bytes
literals.

..

.. bpo: 37757
.. date: 2019-08-05-14-22-59
.. nonce: lRv5HX
.. section: Core and Builtins

:pep:`572`: As described in the PEP, assignment expressions now raise
:exc:`SyntaxError` when their interaction with comprehension scoping results
in an ambiguous target scope.

The ``TargetScopeError`` subclass originally proposed by the PEP has been
removed in favour of just raising regular syntax errors for the disallowed
cases.

..

.. bpo: 36311
.. date: 2019-08-02-15-01-33
.. nonce: uY5vt-
.. section: Core and Builtins

Decoding bytes objects larger than 2GiB is faster and no longer fails when a
multibyte characters spans a chunk boundary.

..

.. bpo: 37433
.. date: 2019-06-27-15-01-14
.. nonce: amNGqr
.. section: Core and Builtins

Fix ``SyntaxError`` indicator printing too many spaces for multi-line
strings - by Anthony Sottile.

..

.. bpo: 20523
.. date: 2019-02-15-20-42-36
.. nonce: rRLrvr
.. section: Core and Builtins

``pdb.Pdb`` supports ~/.pdbrc in Windows 7. Patch by Tim Hopper and Dan
Lidral-Porter.

..

.. bpo: 37834
.. date: 2019-08-29-16-41-36
.. nonce: FThnsh
.. section: Library

Prevent shutil.rmtree exception when built on non-Windows system without fd
system call support, like older versions of macOS.

..

.. bpo: 37965
.. date: 2019-08-28-14-04-18
.. nonce: 7xGE-C
.. section: Library

Fix C compiler warning caused by distutils.ccompiler.CCompiler.has_function.

..

.. bpo: 37960
.. date: 2019-08-27-10-52-13
.. nonce: CTY7Lw
.. section: Library

``repr()`` of buffered and text streams now silences only expected
exceptions when get the value of "name" and "mode" attributes.

..

.. bpo: 37951
.. date: 2019-08-27-10-03-48
.. nonce: MfRQgL
.. section: Library

Most features of the subprocess module now work again in subinterpreters.
Only *preexec_fn* is restricted in subinterpreters.

..

.. bpo: 36205
.. date: 2019-08-27-03-53-26
.. nonce: AfkGRl
.. section: Library

Fix the rusage implementation of time.process_time() to correctly report the
sum of the system and user CPU time.

..

.. bpo: 37950
.. date: 2019-08-26-10-45-51
.. nonce: -K1IKT
.. section: Library

Fix :func:`ast.dump` when call with incompletely initialized node.

..

.. bpo: 34679
.. date: 2019-08-25-18-07-48
.. nonce: HECzL7
.. section: Library

Restores instantiation of Windows IOCP event loops from the non-main thread.

..

.. bpo: 36917
.. date: 2019-08-25-14-56-42
.. nonce: GBxdw2
.. section: Library

Add default implementation of the :meth:`ast.NodeVisitor.visit_Constant`
method which emits a deprecation warning and calls corresponding methody
``visit_Num()``, ``visit_Str()``, etc.

..

.. bpo: 37798
.. date: 2019-08-24-16-54-49
.. nonce: 7mRQCk
.. section: Library

Update test_statistics.py to verify that the statistics module works well
for both C and Python implementations. Patch by Dong-hee Na

..

.. bpo: 26589
.. date: 2019-08-23-00-55-19
.. nonce: M1xyxG
.. section: Library

Added a new status code to the http module: 451
UNAVAILABLE_FOR_LEGAL_REASONS

..

.. bpo: 37915
.. date: 2019-08-22-16-13-27
.. nonce: xyoZI5
.. section: Library

Fix a segmentation fault that appeared when comparing instances of
``datetime.timezone`` and ``datetime.tzinfo`` objects. Patch by Pablo
Galindo.

..

.. bpo: 37868
.. date: 2019-08-17-22-33-54
.. nonce: hp64fi
.. section: Library

Fix dataclasses.is_dataclass when given an instance that never raises
AttributeError in __getattr__.  That is, an object that returns something
for __dataclass_fields__ even if it's not a dataclass.

..

.. bpo: 37811
.. date: 2019-08-14-21-41-07
.. nonce: d1xYj7
.. section: Library

Fix ``socket`` module's ``socket.connect(address)`` function being unable to
establish connection in case of interrupted system call. The problem was
observed on all OSes which ``poll(2)`` system call can take only
non-negative integers and -1 as a timeout value.

..

.. bpo: 21131
.. date: 2019-08-14-15-34-23
.. nonce: 0MMQRi
.. section: Library

Fix ``faulthandler.register(chain=True)`` stack. faulthandler now allocates
a dedicated stack of ``SIGSTKSZ*2`` bytes, instead of just ``SIGSTKSZ``
bytes. Calling the previous signal handler in faulthandler signal handler
uses more than ``SIGSTKSZ`` bytes of stack memory on some platforms.

..

.. bpo: 37798
.. date: 2019-08-14-13-51-24
.. nonce: AmXrik
.. section: Library

Add C fastpath for statistics.NormalDist.inv_cdf() Patch by Dong-hee Na

..

.. bpo: 37819
.. date: 2019-08-11-10-34-19
.. nonce: LVJls-
.. section: Library

Add Fraction.as_integer_ratio() to match the corresponding methods in bool,
int, float, and decimal.

..

.. bpo: 37810
.. date: 2019-08-10-12-33-27
.. nonce: d4zbvB
.. section: Library

Fix :mod:`difflib` ``?`` hint in diff output when dealing with tabs.  Patch
by Anthony Sottile.

..

.. bpo: 37772
.. date: 2019-08-07-23-48-09
.. nonce: hLCvdn
.. section: Library

In ``zipfile.Path``, when adding implicit dirs, ensure that ancestral
directories are added and that duplicates are excluded.

..

.. bpo: 28292
.. date: 2019-08-04-11-47-58
.. nonce: vkihH5
.. section: Library

Mark calendar.py helper functions as being private.  The follows PEP 8
guidance to maintain the style conventions in the module and it addresses a
known case of user confusion.

..

.. bpo: 18049
.. date: 2019-08-02-16-44-42
.. nonce: OA4qBL
.. section: Library

Add definition of THREAD_STACK_SIZE for AIX in Python/thread_pthread.h The
default thread stacksize caused crashes with the default recursion limit
Patch by M Felt

..

.. bpo: 37738
.. date: 2019-08-01-17-11-16
.. nonce: A3WWcT
.. section: Library

Fix the implementation of curses ``addch(str, color_pair)``: pass the color
pair to ``setcchar()``, instead of always passing 0 as the color pair.

..

.. bpo: 37723
.. date: 2019-07-31-16-49-01
.. nonce: zq6tw8
.. section: Library

Fix performance regression on regular expression parsing with huge character
sets. Patch by Yann Vaginay.

..

.. bpo: 32178
.. date: 2019-07-30-22-41-05
.. nonce: X-IFLe
.. section: Library

Fix IndexError in :mod:`email` package when trying to parse invalid address
fields starting with ``:``.

..

.. bpo: 37685
.. date: 2019-07-28-22-25-25
.. nonce: _3bN9f
.. section: Library

Fixed comparisons of :class:`datetime.timedelta` and
:class:`datetime.timezone`.

..

.. bpo: 37695
.. date: 2019-07-27-20-21-03
.. nonce: QANdvg
.. section: Library

Correct :func:`curses.unget_wch` error message.  Patch by Anthony Sottile.

..

.. bpo: 37354
.. date: 2019-07-25-10-28-40
.. nonce: RT3_3H
.. section: Library

Make Activate.ps1 Powershell script static to allow for signing it.

..

.. bpo: 37664
.. date: 2019-07-24-18-27-44
.. nonce: o-GYZC
.. section: Library

Update wheels bundled with ensurepip (pip 19.2.3 and setuptools 41.2.0)

..

.. bpo: 37642
.. date: 2019-07-21-20-59-31
.. nonce: L61Bvy
.. section: Library

Allowed the pure Python implementation of :class:`datetime.timezone` to
represent sub-minute offsets close to minimum and maximum boundaries,
specifically in the ranges (23:59, 24:00) and (-23:59, 24:00). Patch by
Ngalim Siregar

..

.. bpo: 16970
.. date: 2019-07-19-01-46-56
.. nonce: GEASf5
.. section: Library

Adding a value error when an invalid value in passed to nargs Patch by
Robert Leenders

..

.. bpo: 37587
.. date: 2019-07-13-16-02-48
.. nonce: fd-1aF
.. section: Library

Make json.loads faster for long strings. (Patch by Marco Paolini)

..

.. bpo: 18378
.. date: 2019-07-13-13-40-12
.. nonce: NHcojp
.. section: Library

Recognize "UTF-8" as a valid value for LC_CTYPE in locale._parse_localename.

..

.. bpo: 37531
.. date: 2019-07-09-19-38-26
.. nonce: GX7s8S
.. section: Library

"python3 -m test -jN --timeout=TIMEOUT" now kills a worker process if it
runs longer than *TIMEOUT* seconds.

..

.. bpo: 37482
.. date: 2019-07-09-11-20-21
.. nonce: auzvev
.. section: Library

Fix serialization of display name in originator or destination address
fields with both encoded words and special chars.

..

.. bpo: 37372
.. date: 2019-06-22-12-30-00
.. nonce: kIKqZ6
.. section: Library

Fix error unpickling datetime.time objects from Python 2 with seconds>=24.
Patch by Justin Blanchard.

..

.. bpo: 37085
.. date: 2019-06-18-16-29-31
.. nonce: GeYaD6
.. section: Library

Add the optional Linux SocketCAN Broadcast Manager constants, used as flags
to configure the BCM behaviour, in the socket module.  Patch by Karl Ding.

..

.. bpo: 36871
.. date: 2019-05-12-12-58-37
.. nonce: 6xiEHZ
.. section: Library

Ensure method signature is used instead of constructor signature of a class
while asserting mock object against method calls. Patch by Karthikeyan
Singaravelan.

..

.. bpo: 36582
.. date: 2019-05-07-17-42-36
.. nonce: L_dxR6
.. section: Library

Fix ``UserString.encode()`` to correctly return ``bytes`` rather than a
``UserString`` instance.

..

.. bpo: 34775
.. date: 2018-09-23-03-18-52
.. nonce: vHeuHk
.. section: Library

Division handling of PurePath now returns NotImplemented instead of raising
a TypeError when passed something other than an instance of str or PurePath.
Patch by Roger Aiudi.

..

.. bpo: 37979
.. date: 2019-08-29-10-40-05
.. nonce: TAUx_E
.. section: Documentation

Added a link to dateutil.parser.isoparse in the datetime.fromisoformat
documentation. Patch by Paul Ganssle

..

.. bpo: 37759
.. date: 2019-08-04-19-20-58
.. nonce: EHRF4i
.. section: Documentation

Beginning edits to Whatsnew 3.8

..

.. bpo: 37726
.. date: 2019-07-31-11-40-06
.. nonce: h-3o9a
.. section: Documentation

Stop recommending getopt in the tutorial for command line argument parsing
and promote argparse.

..

.. bpo: 37256
.. date: 2019-07-16-14-48-12
.. nonce: qJTrBb
.. section: Documentation

Fix wording of arguments for :class:`Request` in :mod:`urllib.request`

..

.. bpo: 37004
.. date: 2019-05-22-04-30-07
.. nonce: BRgxrt
.. section: Documentation

In the documentation for difflib, a note was added explicitly warning that
the results of SequenceMatcher's ratio method may depend on the order of the
input strings.

..

.. bpo: 36487
.. date: 2019-04-02-19-23-00
.. nonce: Jg6-MG
.. section: Documentation

Make C-API docs clear about what the "main" interpreter is.

..

.. bpo: 37805
.. date: 2019-08-25-19-51-46
.. nonce: Kl1sti
.. section: Tests

Add tests for json.dump(..., skipkeys=True). Patch by Dong-hee Na.

..

.. bpo: 37707
.. date: 2019-07-29-11-36-16
.. nonce: Sm-dGk
.. section: Build

Mark some individual tests to skip when --pgo is used.  The tests marked
increase the PGO task time significantly and likely don't help improve
optimization of the final executable.

..

.. bpo: 37549
.. date: 2019-08-22-09-04-44
.. nonce: TpKI3M
.. section: Windows

:func:`os.dup` no longer fails for standard streams on Windows 7.

..

.. bpo: 1311
.. date: 2019-08-21-12-58-18
.. nonce: BoW1wU
.. section: Windows

The ``nul`` file on Windows now returns True from :func:`~os.path.exists`
and a valid result from :func:`os.stat` with ``S_IFCHR`` set.

..

.. bpo: 9949
.. date: 2019-08-14-13-40-15
.. nonce: zW45Ks
.. section: Windows

Enable support for following symlinks in :func:`os.realpath`.

..

.. bpo: 37834
.. date: 2019-08-12-12-00-24
.. nonce: VB2QVj
.. section: Windows

Treat all name surrogate reparse points on Windows in :func:`os.lstat` and
other reparse points as regular files in :func:`os.stat`.

..

.. bpo: 36266
.. date: 2019-08-08-18-05-27
.. nonce: x4eZU3
.. section: Windows

Add the module name in the formatted error message when DLL load fail
happens during module import in ``_PyImport_FindSharedFuncptrWindows()``.
Patch by Srinivas Nyayapati.

..

.. bpo: 25172
.. date: 2019-08-06-18-09-18
.. nonce: Akreij
.. section: Windows

Trying to import the :mod:`crypt` module on Windows will result in an
:exc:`ImportError` with a message explaining that the module isn't supported
on Windows. On other platforms, if the underlying ``_crypt`` module is not
available, the ImportError will include a message explaining the problem.

..

.. bpo: 37778
.. date: 2019-08-06-13-54-12
.. nonce: AY1XhH
.. section: Windows

Fixes the icons used for file associations to the Microsoft Store package.

..

.. bpo: 37734
.. date: 2019-08-06-09-35-12
.. nonce: EoJ9Nh
.. section: Windows

Fix use of registry values to launch Python from Microsoft Store app.

..

.. bpo: 28269
.. date: 2019-05-05-05-23-34
.. nonce: -MOHI7
.. section: Windows

Replace use of :c:func:`strcasecmp` for the system function
:c:func:`_stricmp`. Patch by Minmin Gong.

..

.. bpo: 18049
.. date: 2019-07-13-15-58-18
.. nonce: MklhQQ
.. section: macOS

Increase the default stack size of threads from 5MB to 16MB on macOS, to
match the stack size of the main thread. This avoids crashes on deep
recursion in threads.

..

.. bpo: 37824
.. date: 2019-08-26-00-41-53
.. nonce: YY5jAI
.. section: IDLE

Properly handle user input warnings in IDLE shell. Cease turning
SyntaxWarnings into SyntaxErrors.

..

.. bpo: 37929
.. date: 2019-08-24-22-00-33
.. nonce: jb7523
.. section: IDLE

IDLE Settings dialog now closes properly when there is no shell window.

..

.. bpo: 37849
.. date: 2019-08-14-09-43-15
.. nonce: -bcYF3
.. section: IDLE

Fixed completions list appearing too high or low when shown above the
current line.

..

.. bpo: 36419
.. date: 2019-08-04-17-10-01
.. nonce: TJZqOc
.. section: IDLE

Refactor IDLE autocomplete and improve testing.

..

.. bpo: 37748
.. date: 2019-08-04-15-27-50
.. nonce: 0vf6pg
.. section: IDLE

Reorder the Run menu.  Put the most common choice, Run Module, at the top.

..

.. bpo: 37942
.. date: 2019-08-24-12-11-30
.. nonce: 7H8N9a
.. section: Tools/Demos

Improve ArgumentClinic converter for floats.

..

.. bpo: 37034
.. date: 2019-05-27-16-13-08
.. nonce: zbTgy8
.. section: Tools/Demos

Argument Clinic now uses the argument name on errors with keyword-only
argument instead of their position. Patch contributed by Rémi Lapeyre.

..

.. bpo: 36763
.. date: 2019-08-23-18-45-11
.. nonce: q3Kh8Z
.. section: C API

Options added by ``PySys_AddXOption()`` are now handled the same way than
``PyConfig.xoptions`` and command line ``-X`` options.

..

.. bpo: 37926
.. date: 2019-08-23-11-35-55
.. nonce: hnI5IQ
.. section: C API

Fix a crash in ``PySys_SetArgvEx(0, NULL, 0)``.