Misc/NEWS.d/3.8.0b2.rst

.. bpo: 37363
.. date: 2019-07-01-10-31-14
.. nonce: fSjatj
.. release date: 2019-07-04
.. section: Security

Adds audit events for the range of supported run commands (see
:ref:`using-on-general`).

..

.. bpo: 37463
.. date: 2019-07-01-08-46-14
.. nonce: 1CHwjE
.. section: Security

ssl.match_hostname() no longer accepts IPv4 addresses with additional text
after the address and only quad-dotted notation without trailing
whitespaces. Some inet_aton() implementations ignore whitespace and all data
after whitespace, e.g. '127.0.0.1 whatever'.

..

.. bpo: 37363
.. date: 2019-06-21-15-58-59
.. nonce: diouyl
.. section: Security

Adds audit events for :mod:`ensurepip`, :mod:`ftplib`, :mod:`glob`,
:mod:`imaplib`, :mod:`nntplib`, :mod:`pdb`, :mod:`poplib`, :mod:`shutil`,
:mod:`smtplib`, :mod:`sqlite3`, :mod:`subprocess`, :mod:`telnetlib`,
:mod:`tempfile` and :mod:`webbrowser`, as well as :func:`os.listdir`,
:func:`os.scandir` and :func:`breakpoint`.

..

.. bpo: 37364
.. date: 2019-06-21-14-42-53
.. nonce: IIRc2s
.. section: Security

:func:`io.open_code` is now used when reading :file:`.pth` files.

..

.. bpo: 34631
.. date: 2019-06-17-09-34-25
.. nonce: DBfM4j
.. section: Security

Updated OpenSSL to 1.1.1c in Windows installer

..

.. bpo: 37467
.. date: 2019-07-01-12-22-44
.. nonce: u-XyEu
.. section: Core and Builtins

Fix :func:`sys.excepthook` and :c:func:`PyErr_Display` if a filename is a
bytes string. For example, for a SyntaxError exception where the filename
attribute is a bytes string.

..

.. bpo: 37417
.. date: 2019-06-26-18-41-00
.. nonce: VsZeHL
.. section: Core and Builtins

:meth:`bytearray.extend` now correctly handles errors that arise during
iteration. Patch by Brandt Bucher.

..

.. bpo: 24214
.. date: 2019-06-22-12-45-20
.. nonce: hIiHeD
.. section: Core and Builtins

Improved support of the surrogatepass error handler in the UTF-8 and UTF-16
incremental decoders.

..

.. bpo: 35224
.. date: 2019-06-17-06-03-55
.. nonce: FHWPGv
.. section: Core and Builtins

Reverse evaluation order of key: value in dict comprehensions as proposed in
PEP 572. I.e. in ``{k: v for ...}``, ``k`` will be evaluated before ``v``.

..

.. bpo: 37316
.. date: 2019-06-17-03-53-16
.. nonce: LytDX_
.. section: Core and Builtins

Fix the :c:func:`PySys_Audit` call in :class:`mmap.mmap`.

..

.. bpo: 37269
.. date: 2019-06-14-06-32-33
.. nonce: SjVVAe
.. section: Core and Builtins

Fix a bug in the peephole optimizer that was not treating correctly constant
conditions with binary operators. Patch by Pablo Galindo.

..

.. bpo: 37213
.. date: 2019-06-11-11-15-19
.. nonce: UPii5K
.. section: Core and Builtins

Handle correctly negative line offsets in the peephole optimizer. Patch by
Pablo Galindo.

..

.. bpo: 37219
.. date: 2019-06-10-23-18-31
.. nonce: jPSufq
.. section: Core and Builtins

Remove errorneous optimization for empty set differences.

..

.. bpo: 36922
.. date: 2019-06-06-13-59-52
.. nonce: EMZ3TF
.. section: Core and Builtins

Slot functions optimize any callable with ``Py_TPFLAGS_METHOD_DESCRIPTOR``
instead of only instances of ``function``.

..

.. bpo: 36974
.. date: 2019-06-06-11-00-55
.. nonce: wdzzym
.. section: Core and Builtins

The slot ``tp_vectorcall_offset`` is inherited unconditionally to support
``super().__call__()`` when the base class uses vectorcall.

..

.. bpo: 37160
.. date: 2019-06-05-09-24-17
.. nonce: O3IAY3
.. section: Core and Builtins

:func:`threading.get_native_id` now also supports NetBSD.

..

.. bpo: 37077
.. date: 2019-05-28-11-47-44
.. nonce: S1h0Fc
.. section: Core and Builtins

Add :func:`threading.get_native_id` support for AIX. Patch by M. Felt

..

.. bpo: 37440
.. date: 2019-06-28-16-40-17
.. nonce: t3wX-N
.. section: Library

http.client now enables TLS 1.3 post-handshake authentication for default
context or if a cert_file is passed to HTTPSConnection.

..

.. bpo: 37437
.. date: 2019-06-27-20-33-50
.. nonce: du39_A
.. section: Library

Update vendorized expat version to 2.2.7.

..

.. bpo: 37428
.. date: 2019-06-27-13-27-02
.. nonce: _wcwUd
.. section: Library

SSLContext.post_handshake_auth = True no longer sets
SSL_VERIFY_POST_HANDSHAKE verify flag for client connections. Although the
option is documented as ignored for clients, OpenSSL implicitly enables cert
chain validation when the flag is set.

..

.. bpo: 37420
.. date: 2019-06-26-22-25-05
.. nonce: CxFJ09
.. section: Library

:func:`os.sched_setaffinity` now correctly handles errors that arise during
iteration over its ``mask`` argument. Patch by Brandt Bucher.

..

.. bpo: 37412
.. date: 2019-06-26-16-28-59
.. nonce: lx0VjC
.. section: Library

The :func:`os.getcwdb` function now uses the UTF-8 encoding on Windows,
rather than the ANSI code page: see :pep:`529` for the rationale. The
function is no longer deprecated on Windows.

..

.. bpo: 29412
.. date: 2019-06-25-19-27-25
.. nonce: n4Zqdh
.. section: Library

Fix IndexError in parsing a header value ending unexpectedly. Patch by
Abhilash Raj.

..

.. bpo: 36546
.. date: 2019-06-25-05-07-48
.. nonce: RUcxaK
.. section: Library

The *dist* argument for statistics.quantiles() is now positional only. The
current name doesn't reflect that the argument can be either a dataset or a
distribution.  Marking the parameter as positional avoids confusion and
makes it possible to change the name later.

..

.. bpo: 37394
.. date: 2019-06-25-02-10-00
.. nonce: srZ1zx
.. section: Library

Fix a bug that was causing the :mod:`queue` module to fail if the
accelerator module was not available. Patch by Pablo Galindo.

..

.. bpo: 33972
.. date: 2019-06-15-14-39-50
.. nonce: XxnNPw
.. section: Library

Email with single part but content-type set to ``multipart/*`` doesn't raise
AttributeError anymore.

..

.. bpo: 37280
.. date: 2019-06-14-13-30-47
.. nonce: Fxur0F
.. section: Library

Use threadpool for reading from file for sendfile fallback mode.

..

.. bpo: 37279
.. date: 2019-06-14-13-25-56
.. nonce: OHlW6l
.. section: Library

Fix asyncio sendfile support when sendfile sends extra data in fallback
mode.

..

.. bpo: 19865
.. date: 2019-06-14-08-30-16
.. nonce: FRGH4I
.. section: Library

:func:`ctypes.create_unicode_buffer()` now also supports non-BMP characters
on platforms with 16-bit :c:type:`wchar_t` (for example, Windows and AIX).

..

.. bpo: 37210
.. date: 2019-06-12-16-10-50
.. nonce: r4yMg6
.. section: Library

Allow pure Python implementation of :mod:`pickle` to work even when the C
:mod:`_pickle` module is unavailable.

..

.. bpo: 35922
.. date: 2019-06-11-19-34-29
.. nonce: rxpzWr
.. section: Library

Fix :meth:`RobotFileParser.crawl_delay` and
:meth:`RobotFileParser.request_rate` to return ``None`` rather than raise
:exc:`AttributeError` when no relevant rule is defined in the robots.txt
file.  Patch by Rémi Lapeyre.

..

.. bpo: 35766
.. date: 2019-06-11-16-41-40
.. nonce: v1Kj-T
.. section: Library

Change the format of feature_version to be a (major, minor) tuple.

..

.. bpo: 36607
.. date: 2019-06-11-13-52-04
.. nonce: 5_mJkQ
.. section: Library

Eliminate :exc:`RuntimeError` raised by :func:`asyncio.all_tasks()` if
internal tasks weak set is changed by another thread during iteration.

..

.. bpo: 18748
.. date: 2019-06-11-01-54-19
.. nonce: ADqCkq
.. section: Library

:class:`_pyio.IOBase` destructor now does nothing if getting the ``closed``
attribute fails to better mimick :class:`_io.IOBase` finalizer.

..

.. bpo: 36402
.. date: 2019-06-11-00-35-02
.. nonce: b0IJVp
.. section: Library

Fix a race condition at Python shutdown when waiting for threads. Wait until
the Python thread state of all non-daemon threads get deleted (join all
non-daemon threads), rather than just wait until non-daemon Python threads
complete.

..

.. bpo: 34886
.. date: 2019-06-08-16-03-19
.. nonce: Ov-pc9
.. section: Library

Fix an unintended ValueError from :func:`subprocess.run` when checking for
conflicting `input` and `stdin` or `capture_output` and `stdout` or `stderr`
args when they were explicitly provided but with `None` values within a
passed in `**kwargs` dict rather than as passed directly by name. Patch
contributed by Rémi Lapeyre.

..

.. bpo: 37173
.. date: 2019-06-08-11-33-48
.. nonce: 0e_8gS
.. section: Library

The exception message for ``inspect.getfile()`` now correctly reports the
passed class rather than the builtins module.

..

.. bpo: 37178
.. date: 2019-06-07-17-16-09
.. nonce: Day_oB
.. section: Library

Give math.perm() a one argument form that means the same as
math.factorial().

..

.. bpo: 37178
.. date: 2019-06-07-17-11-34
.. nonce: b1StSv
.. section: Library

For math.perm(n, k), let k default to n, giving the same result as
factorial.

..

.. bpo: 37163
.. date: 2019-06-07-08-18-05
.. nonce: 36JkUh
.. section: Library

Deprecated passing ``obj`` argument of :func:`dataclasses.replace` as
keyword argument.

..

.. bpo: 37165
.. date: 2019-06-05-11-48-19
.. nonce: V_rwfE
.. section: Library

Converted _collections._count_elements to use the Argument Clinic.

..

.. bpo: 34767
.. date: 2019-06-04-23-44-52
.. nonce: BpDShN
.. section: Library

Do not always create a :class:`collections.deque` in :class:`asyncio.Lock`.

..

.. bpo: 37158
.. date: 2019-06-04-22-25-38
.. nonce: JKm15S
.. section: Library

Speed-up statistics.fmean() by switching from a function to a generator.

..

.. bpo: 37150
.. date: 2019-06-04-14-44-41
.. nonce: TTzHxj
.. section: Library

`argparse._ActionsContainer.add_argument` now throws error, if someone
accidentally pass FileType class object instead of instance of FileType as
`type` argument

..

.. bpo: 35621
.. date: 2019-05-28-19-03-46
.. nonce: Abc1lf
.. section: Library

Support running asyncio subprocesses when execution event loop in a thread
on UNIX.

..

.. bpo: 36520
.. date: 2019-05-28-02-37-00
.. nonce: W4tday
.. section: Library

Lengthy email headers with UTF-8 characters are now properly encoded when
they are folded. Patch by Jeffrey Kintscher.

..

.. bpo: 30835
.. date: 2019-05-27-15-29-46
.. nonce: 3FoaWH
.. section: Library

Fixed a bug in email parsing where a message with invalid bytes in
content-transfer-encoding of a multipart message can cause an
AttributeError. Patch by Andrew Donnellan.

..

.. bpo: 35805
.. date: 2019-05-17-15-11-08
.. nonce: E4YwYz
.. section: Library

Add parser for Message-ID header and add it to default HeaderRegistry. This
should prevent folding of Message-ID using RFC 2048 encoded words.

..

.. bpo: 35070
.. date: 2019-05-09-18-50-55
.. nonce: 4vaqNL
.. section: Library

posix.getgrouplist() now works correctly when the user belongs to
NGROUPS_MAX supplemental groups. Patch by Jeffrey Kintscher.

..

.. bpo: 32627
.. date: 2019-02-03-19-13-08
.. nonce: b68f64
.. section: Library

Fix compile error when ``_uuid`` headers conflicting included.

..

.. bpo: 11122
.. date: 2018-11-12-19-08-50
.. nonce: Gj7BQn
.. section: Library

Distutils won't check for rpmbuild in specified paths only.

..

.. bpo: 4963
.. date: 2017-08-15-11-24-41
.. nonce: LRYres
.. section: Library

Fixed non-deterministic behavior related to mimetypes extension mapping and
module reinitialization.

..

.. bpo: 34903
.. date: 2019-06-17-09-36-46
.. nonce: r_wGRc
.. section: Documentation

Documented that in :meth:`datetime.datetime.strptime()`, the leading zero in
some two-digit formats is optional. Patch by Mike Gleen.

..

.. bpo: 37421
.. date: 2019-07-03-00-05-28
.. nonce: ORGRSG
.. section: Tests

test_distutils.test_build_ext() is now able to remove the temporary
directory on Windows: don't import the newly built C extension ("xx") in the
current process, but test it in a separated process.

..

.. bpo: 37421
.. date: 2019-07-02-23-29-06
.. nonce: WEfc5A
.. section: Tests

test_concurrent_futures now cleans up multiprocessing to remove immediately
temporary directories created by multiprocessing.util.get_temp_dir().

..

.. bpo: 37421
.. date: 2019-07-02-23-20-35
.. nonce: HCkKWz
.. section: Tests

test_winconsoleio doesn't leak a temporary file anymore: use
tempfile.TemporaryFile() to remove it when the test completes.

..

.. bpo: 37421
.. date: 2019-07-01-19-57-26
.. nonce: NFH1f0
.. section: Tests

multiprocessing tests now explicitly call ``_run_finalizers()`` to
immediately remove temporary directories created by tests.

..

.. bpo: 37199
.. date: 2019-06-29-23-56-28
.. nonce: FHDsLf
.. section: Tests

Fix test failures when IPv6 is unavailable or disabled.

..

.. bpo: 37335
.. date: 2019-06-28-16-37-52
.. nonce: o5S2hY
.. section: Tests

Remove no longer necessary code from c locale coercion tests

..

.. bpo: 37421
.. date: 2019-06-27-00-37-59
.. nonce: rVJb3x
.. section: Tests

Fix test_shutil to no longer leak temporary files.

..

.. bpo: 37411
.. date: 2019-06-26-15-28-45
.. nonce: 5lGNhM
.. section: Tests

Fix test_wsgiref.testEnviron() to no longer depend on the environment
variables (don't fail if "X" variable is set).

..

.. bpo: 37400
.. date: 2019-06-25-16-02-43
.. nonce: cx_EWv
.. section: Tests

Fix test_os.test_chown(): use os.getgroups() rather than grp.getgrall() to
get groups. Rename also the test to test_chown_gid().

..

.. bpo: 37359
.. date: 2019-06-24-10-47-07
.. nonce: CkdtyO
.. section: Tests

Add --cleanup option to python3 -m test to remove ``test_python_*``
directories of previous failed jobs. Add "make cleantest" to run ``python3
-m test --cleanup``.

..

.. bpo: 37362
.. date: 2019-06-21-15-47-33
.. nonce: D3xppx
.. section: Tests

test_gdb no longer fails if it gets an "unexpected" message on stderr: it
now ignores stderr. The purpose of test_gdb is to test that python-gdb.py
commands work as expected, not to test gdb.

..

.. bpo: 35998
.. date: 2019-06-14-17-05-49
.. nonce: yX82oD
.. section: Tests

Avoid TimeoutError in test_asyncio: test_start_tls_server_1()

..

.. bpo: 37278
.. date: 2019-06-14-12-21-47
.. nonce: z0HUOr
.. section: Tests

Fix test_asyncio ProactorLoopCtrlC: join the thread to prevent leaking a
running thread and leaking a reference.

..

.. bpo: 37261
.. date: 2019-06-13-12-19-56
.. nonce: NuKFVo
.. section: Tests

Fix :func:`test.support.catch_unraisable_exception`: its __exit__() method
now ignores unraisable exception raised when clearing its ``unraisable``
attribute.

..

.. bpo: 37169
.. date: 2019-06-07-12-23-15
.. nonce: yfXTFg
.. section: Tests

Rewrite ``_PyObject_IsFreed()`` unit tests.

..

.. bpo: 37153
.. date: 2019-06-04-18-30-39
.. nonce: 711INB
.. section: Tests

``test_venv.test_mutiprocessing()`` now explicitly calls
``pool.terminate()`` to wait until the pool completes.

..

.. bpo: 28009
.. date: 2019-04-11-07-59-43
.. nonce: s85urF
.. section: Tests

Modify the test_uuid logic to test when a program is available AND can be
used to obtain a MACADDR as basis for an UUID. Patch by M. Felt

..

.. bpo: 37189
.. date: 2019-06-17-09-40-59
.. nonce: j5ebdT
.. section: Build

Many ``PyRun_XXX()`` functions like :c:func:`PyRun_String` were no longer
exported in ``libpython38.dll`` by mistake. Export them again to fix the ABI
compatibiliy.

..

.. bpo: 10945
.. date: 2019-07-01-12-38-48
.. nonce: s0YBHG
.. section: Windows

Officially drop support for creating bdist_wininst installers on non-Windows
systems.

..

.. bpo: 37369
.. date: 2019-06-28-09-44-08
.. nonce: 1iVpxq
.. section: Windows

Fixes path for :data:`sys.executable` when running from the Microsoft Store.

..

.. bpo: 37351
.. date: 2019-06-20-12-50-32
.. nonce: asTnVW
.. section: Windows

Removes libpython38.a from standard Windows distribution.

..

.. bpo: 35360
.. date: 2019-06-18-09-05-08
.. nonce: tdqSmo
.. section: Windows

Update Windows builds to use SQLite 3.28.0.

..

.. bpo: 37267
.. date: 2019-06-13-04-15-51
.. nonce: Ygo5ef
.. section: Windows

On Windows, :func:`os.dup` no longer creates an inheritable fd when handling
a character file.

..

.. bpo: 36779
.. date: 2019-06-11-15-41-34
.. nonce: 0TMw6f
.. section: Windows

Ensure ``time.tzname`` is correct on Windows when the active code page is
set to CP_UTF7 or CP_UTF8.

..

.. bpo: 34602
.. date: 2019-07-02-01-06-47
.. nonce: 10d4wl
.. section: macOS

Avoid test suite failures on macOS by no longer calling resource.setrlimit
to increase the process stack size limit at runtime.  The runtime change is
no longer needed since the interpreter is being built with a larger default
stack size.

..

.. bpo: 35360
.. date: 2019-06-18-08-58-30
.. nonce: -CWbfy
.. section: macOS

Update macOS installer to use SQLite 3.28.0.

..

.. bpo: 34631
.. date: 2019-06-18-00-30-40
.. nonce: vSifcv
.. section: macOS

Updated OpenSSL to 1.1.1c in macOS installer.

..

.. bpo: 37325
.. date: 2019-06-18-16-40-05
.. nonce: GssOf1
.. section: IDLE

Fix tab focus traversal order for help source and custom run dialogs.

..

.. bpo: 37321
.. date: 2019-06-17-16-35-30
.. nonce: zVTTGS
.. section: IDLE

Both subprocess connection error messages now refer to the 'Startup failure'
section of the IDLE doc.

..

.. bpo: 37177
.. date: 2019-06-07-00-17-41
.. nonce: voU6pQ
.. section: IDLE

Properly 'attach' search dialogs to their main window so that they behave
like other dialogs and do not get hidden behind their main window.

..

.. bpo: 37039
.. date: 2019-06-04-23-27-33
.. nonce: FN_fBf
.. section: IDLE

Adjust "Zoom Height" to individual screens by momemtarily maximizing the
window on first use with a particular screen.  Changing screen settings may
invalidate the saved height.  While a window is maximized, "Zoom Height" has
no effect.

..

.. bpo: 35763
.. date: 2019-06-04-20-36-24
.. nonce: 7XdoWz
.. section: IDLE

Make calltip reminder about '/' meaning positional-only less obtrusive by
only adding it when there is room on the first line.

..

.. bpo: 5680
.. date: 2019-06-03-00-39-29
.. nonce: VCQfOO
.. section: IDLE

Add 'Run... Customized' to the Run menu to run a module with customized
settings.  Any 'command line arguments' entered are added to sys.argv. One
can suppress the normal Shell main module restart.

..

.. bpo: 36763
.. date: 2019-06-28-15-49-16
.. nonce: zrmgki
.. section: C API

Add :func:`PyConfig_SetWideStringList` function.

..

.. bpo: 28805
.. date: 2019-06-14-14-03-51
.. nonce: qZC0N_
.. section: C API

The :const:`METH_FASTCALL` calling convention has been documented.

..

.. bpo: 37221
.. date: 2019-06-12-11-45-36
.. nonce: RhP1E7
.. section: C API

``tp_print`` is put back at the end of the ``PyTypeObject`` structure to
restore support for old code (in particular generated by Cython) setting
``tp_print = 0``. Note that ``tp_print`` will be removed entirely in Python
3.9.

..

.. bpo: 37221
.. date: 2019-06-11-02-50-38
.. nonce: 4tClQT
.. section: C API

The new function :c:func:`PyCode_NewWithPosOnlyArgs` allows to create code
objects like :c:func:`PyCode_New`, but with an extra *posonlyargcount*
parameter for indicating the number of positonal-only arguments.

..

.. bpo: 37215
.. date: 2019-06-10-15-32-34
.. nonce: yzoNyU
.. section: C API

Fix dtrace issue introduce by bpo-36842

..

.. bpo: 37191
.. date: 2019-06-07-10-47-37
.. nonce: iGL1_K
.. section: C API

Python.h does not need compiler support for intermingled declarations (GCC's
``-Wdeclaration-after-statement``), which were added in 3.8.0 Beta 1. Note
that in Python 3.9, intermingled declarations will be needed again.

..

.. bpo: 37170
.. date: 2019-06-06-08-47-04
.. nonce: hO_fpM
.. section: C API

Fix the cast on error in :c:func:`PyLong_AsUnsignedLongLongMask()`.