3.9.0a4 - Cpython — ContextQMD

.. bpo: 39184 .. date: 2020-02-07-23-54-18 .. nonce: v-ue-v .. release date: 2020-02-25 .. section: Security

Add audit events to functions in fcntl, msvcrt, os, resource, shutil, signal and syslog.

.. bpo: 39401 .. date: 2020-01-28-20-54-09 .. nonce: he7h_A .. section: Security

Avoid unsafe DLL load at startup on Windows 7 and earlier.

.. bpo: 39184 .. date: 2020-01-07-00-42-08 .. nonce: fe7NgK .. section: Security

Add audit events to command execution functions in os and pty modules.

.. bpo: 39382 .. date: 2020-02-18-01-40-13 .. nonce: OLSJu9 .. section: Core and Builtins

Fix a use-after-free in the single inheritance path of issubclass(), when the __bases__ of an object has a single reference, and so does its first item. Patch by Yonatan Goldschmidt.

.. bpo: 39573 .. date: 2020-02-14-10-08-53 .. nonce: BIIX2M .. section: Core and Builtins

Update clinic tool to use :c:func:Py_IS_TYPE. Patch by Donghee Na.

.. bpo: 39619 .. date: 2020-02-13-07-35-00 .. nonce: inb_master_chroot .. section: Core and Builtins

Enable use of :func:os.chroot on HP-UX systems.

.. bpo: 39573 .. date: 2020-02-13-01-30-22 .. nonce: uTFj1m .. section: Core and Builtins

Add :c:func:Py_IS_TYPE static inline function to check whether the object o type is type.

.. bpo: 39606 .. date: 2020-02-11-23-59-07 .. nonce: a72Sxc .. section: Core and Builtins

Fix regression caused by fix for bpo-39386, that prevented calling aclose on an async generator that had already been closed or exhausted.

.. bpo: 39579 .. date: 2020-02-07-15-18-35 .. nonce: itNmC0 .. section: Core and Builtins

Change the ending column offset of Attribute nodes constructed in ast_for_dotted_name to point at the end of the current node and not at the end of the last NAME node.

.. bpo: 1635741 .. date: 2020-02-07-12-57-40 .. nonce: ySW6gq .. section: Core and Builtins

Port _crypt extension module to multiphase initialization (:pep:489).

.. bpo: 1635741 .. date: 2020-02-06-09-00-35 .. nonce: oaxe1j .. section: Core and Builtins

Port _contextvars extension module to multiphase initialization (:pep:489).

.. bpo: 39510 .. date: 2020-02-04-10-27-41 .. nonce: PMIh-f .. section: Core and Builtins

Fix segfault in readinto() method on closed BufferedReader.

.. bpo: 39502 .. date: 2020-01-30-14-36-31 .. nonce: IJu0rl .. section: Core and Builtins

Fix :func:time.localtime on 64-bit AIX to support years before 1902 and after 2038. Patch by M Felt.

.. bpo: 39492 .. date: 2020-01-30-01-14-42 .. nonce: eTuy0F .. section: Core and Builtins

Fix a reference cycle in the C Pickler that was preventing the garbage collection of deleted, pickled objects.

.. bpo: 39453 .. date: 2020-01-25-23-51-17 .. nonce: xCOkYk .. section: Core and Builtins

Fixed a possible crash in :meth:list.__contains__ when a list is changed during comparing items. Patch by Donghee Na.

.. bpo: 39434 .. date: 2020-01-24-01-07-04 .. nonce: S5ehj9 .. section: Core and Builtins

:term:floor division of float operation now has a better performance. Also the message of :exc:ZeroDivisionError for this operation is updated. Patch by Donghee Na.

.. bpo: 1635741 .. date: 2020-01-19-11-06-30 .. nonce: 0mjsfm .. section: Core and Builtins

Port _codecs extension module to multiphase initialization (:pep:489).

.. bpo: 1635741 .. date: 2020-01-18-11-06-28 .. nonce: OKROOt .. section: Core and Builtins

Port _bz2 extension module to multiphase initialization (:pep:489).

.. bpo: 1635741 .. date: 2020-01-16-12-00-04 .. nonce: fuqoBG .. section: Core and Builtins

Port _abc extension module to multiphase initialization (:pep:489).

.. bpo: 39320 .. date: 2020-01-15-15-50-22 .. nonce: oWARyk .. section: Core and Builtins

Replace two complex bytecodes for building dicts with two simpler ones. The new bytecodes DICT_MERGE and DICT_UPDATE have been added The old bytecodes BUILD_MAP_UNPACK and BUILD_MAP_UNPACK_WITH_CALL have been removed.

.. bpo: 39219 .. date: 2020-01-05-13-36-08 .. nonce: uHtKd4 .. section: Core and Builtins

Syntax errors raised in the tokenizer now always set correct "text" and "offset" attributes.

.. bpo: 36051 .. date: 2019-12-30-15-56-07 .. nonce: imaVlq .. section: Core and Builtins

Drop the GIL during large bytes.join operations. Patch by Bruce Merry.

.. bpo: 38960 .. date: 2019-12-03-16-41-22 .. nonce: kvoFM0 .. section: Core and Builtins

Fix DTrace build issues on FreeBSD. Patch by David Carlier.

.. bpo: 37207 .. date: 2019-06-09-10-54-31 .. nonce: bLjgLR .. section: Core and Builtins

Speed up calls to range() by about 30%, by using the PEP 590 vectorcall calling convention. Patch by Mark Shannon.

.. bpo: 36144 .. date: 2019-03-02-23-03-34 .. nonce: LRl4LS .. section: Core and Builtins

:class:dict (and :class:collections.UserDict) objects now support PEP 584's merge (|) and update (|=) operators. Patch by Brandt Bucher.

.. bpo: 32856 .. date: 2018-02-16-10-44-24 .. nonce: UjR8SD .. section: Core and Builtins

Optimized the idiom for assignment a temporary variable in comprehensions. Now for y in [expr] in comprehensions is as fast as a simple assignment y = expr.

.. bpo: 30566 .. date: 2020-02-24-03-45-28 .. nonce: qROxty .. section: Library

Fix :exc:IndexError when trying to decode an invalid string with punycode codec.

.. bpo: 39649 .. date: 2020-02-23-21-27-10 .. nonce: qiubSp .. section: Library

Remove obsolete check for __args__ in bdb.Bdb.format_stack_entry.

.. bpo: 39648 .. date: 2020-02-22-12-49-04 .. nonce: Y-9N7F .. section: Library

Expanded :func:math.gcd and :func:math.lcm to handle multiple arguments.

.. bpo: 39681 .. date: 2020-02-21-13-58-40 .. nonce: zN8hf0 .. section: Library

Fix a regression where the C pickle module wouldn't allow unpickling from a file-like object that doesn't expose a readinto() method.

.. bpo: 35950 .. date: 2020-02-21-02-42-41 .. nonce: 9G3-wl .. section: Library

Raise :exc:io.UnsupportedOperation in :meth:io.BufferedReader.truncate when it is called on a read-only :class:io.BufferedReader instance.

.. bpo: 39479 .. date: 2020-02-18-12-37-16 .. nonce: j3UcCq .. section: Library

Add :func:math.lcm function: least common multiple.

.. bpo: 39674 .. date: 2020-02-18-12-31-24 .. nonce: S_zqVM .. section: Library

Revert "Do not expose abstract collection classes in the collections module" change (bpo-25988). Aliases to ABC like collections.Mapping are kept in Python 3.9 to ease transition from Python 2.7, but will be removed in Python 3.10.

.. bpo: 39104 .. date: 2020-02-16-18-49-16 .. nonce: cI5MJY .. section: Library

Fix hanging ProcessPoolExcutor on shutdown(wait=False) when a task has failed pickling.

.. bpo: 39627 .. date: 2020-02-13-18-14-15 .. nonce: Q0scyQ .. section: Library

Fixed TypedDict totality check for inherited keys.

.. bpo: 39474 .. date: 2020-02-12-12-01-26 .. nonce: RZMEUH .. section: Library

Fixed starting position of AST for expressions like (a)(b), (a)[b] and (a).b.

.. bpo: 21016 .. date: 2020-02-12-10-04-39 .. nonce: bFXPH7 .. section: Library

The :mod:pydoc and :mod:trace modules now use the :mod:sysconfig module to get the path to the Python standard library, to support uncommon installation path like /usr/lib64/python3.9/ on Fedora. Patch by Jan Matějek.

.. bpo: 39590 .. date: 2020-02-09-05-51-05 .. nonce: rf98GU .. section: Library

Collections.deque now holds strong references during deque.contains and deque.count, fixing crashes.

.. bpo: 39586 .. date: 2020-02-08-13-37-00 .. nonce: nfTPxX .. section: Library

The distutils bdist_msi command is deprecated in Python 3.9, use bdist_wheel (wheel packages) instead.

.. bpo: 39595 .. date: 2020-02-07-23-14-14 .. nonce: DHwddE .. section: Library

Improved performance of zipfile.Path for files with a large number of entries. Also improved performance and fixed minor issue as published with importlib_metadata 1.5 <https://importlib-metadata.readthedocs.io/en/latest/history.html#v1-5-0>_.

.. bpo: 39350 .. date: 2020-02-06-13-34-52 .. nonce: wRwup1 .. section: Library

Fix regression in :class:fractions.Fraction if the numerator and/or the denominator is an :class:int subclass. The :func:math.gcd function is now used to normalize the numerator and denominator. :func:math.gcd always return a :class:int type. Previously, the GCD type depended on numerator and denominator.

.. bpo: 39567 .. date: 2020-02-06-10-23-32 .. nonce: VpFBxt .. section: Library

Added audit for :func:os.walk, :func:os.fwalk, :meth:pathlib.Path.glob and :meth:pathlib.Path.rglob.

.. bpo: 39559 .. date: 2020-02-05-18-29-14 .. nonce: L8i5YB .. section: Library

Remove unused, undocumented argument getters from :func:uuid.getnode

.. bpo: 38149 .. date: 2020-02-05-11-24-16 .. nonce: GWsjHE .. section: Library

:func:sys.audit is now called only once per call of :func:glob.glob and :func:glob.iglob.

.. bpo: 39546 .. date: 2020-02-03-15-12-51 .. nonce: _Kj0Pn .. section: Library

Fix a regression in :class:~argparse.ArgumentParser where allow_abbrev=False was ignored for long options that used a prefix character other than "-".

.. bpo: 39450 .. date: 2020-02-02-14-46-34 .. nonce: 48R274 .. section: Library

Striped whitespace from docstring before returning it from :func:unittest.case.shortDescription.

.. bpo: 12915 .. date: 2020-02-02-10-08-25 .. nonce: d6r50- .. section: Library

A new function resolve_name has been added to the pkgutil module. This resolves a string of the form 'a.b.c.d' or 'a.b:c.d' to an object. In the example, a.b is a package/module and c.d is an object within that package/module reached via recursive attribute access.

.. bpo: 39353 .. date: 2020-01-30-09-07-16 .. nonce: wTl9hc .. section: Library

The :func:binascii.crc_hqx function is no longer deprecated.

.. bpo: 39493 .. date: 2020-01-30-01-13-19 .. nonce: CbFRi7 .. section: Library

Mark typing.IO.closed as a property

.. bpo: 39491 .. date: 2020-01-29-22-47-12 .. nonce: tdl17b .. section: Library

Add :data:typing.Annotated and include_extras parameter to :func:typing.get_type_hints as part of :pep:593. Patch by Till Varoquaux, documentation by Till Varoquaux and Konstantin Kashin.

.. bpo: 39485 .. date: 2020-01-29-14-58-27 .. nonce: Zy3ot6 .. section: Library

Fix a bug in :func:unittest.mock.create_autospec that would complain about the wrong number of arguments for custom descriptors defined in an extension module returning functions.

.. bpo: 38932 .. date: 2020-01-25-13-41-27 .. nonce: 1pu_8I .. section: Library

Mock fully resets child objects on reset_mock(). Patch by Vegard Stikbakke

.. bpo: 39082 .. date: 2020-01-24-13-24-35 .. nonce: qKgrq_ .. section: Library

Allow AsyncMock to correctly patch static/class methods

.. bpo: 39432 .. date: 2020-01-23-16-08-58 .. nonce: Cee6mi .. section: Library

Implement PEP-489 algorithm for non-ascii "PyInit_..." symbol names in distutils to make it export the correct init symbol also on Windows.

.. bpo: 18819 .. date: 2020-01-20-10-06-19 .. nonce: H4qsoS .. section: Library

Omit devmajor and devminor fields for non-device files in :mod:tarfile archives, enabling bit-for-bit compatibility with GNU tar(1).

.. bpo: 39349 .. date: 2020-01-19-04-12-34 .. nonce: 7CV-LC .. section: Library

Added a new cancel_futures parameter to :meth:concurrent.futures.Executor.shutdown that cancels all pending futures which have not started running, instead of waiting for them to complete before shutting down the executor.

.. bpo: 39274 .. date: 2020-01-15-23-13-03 .. nonce: lpc0-n .. section: Library

bool(fraction.Fraction) now returns a boolean even if (numerator != 0) does not return a boolean (ex: numpy number).

.. bpo: 34793 .. date: 2019-12-09-17-24-29 .. nonce: D82Dyu .. section: Library

Remove support for with (await asyncio.lock): and with (yield from asyncio.lock):. The same is correct for asyncio.Condition and asyncio.Semaphore.

.. bpo: 25597 .. date: 2019-09-12-12-11-05 .. nonce: mPMzVx .. section: Library

Ensure, if wraps is supplied to :class:unittest.mock.MagicMock, it is used to calculate return values for the magic methods instead of using the default return values. Patch by Karthikeyan Singaravelan.

.. bpo: 36350 .. date: 2019-03-18-16-17-59 .. nonce: udRSWE .. section: Library

inspect.Signature.parameters and inspect.BoundArguments.arguments are now dicts instead of OrderedDicts. Patch contributed by Rémi Lapeyre.

.. bpo: 35727 .. date: 2019-01-12-20-39-34 .. nonce: FWrbHn .. section: Library

Fix sys.exit() and sys.exit(None) exit code propagation when used in multiprocessing.Process.

.. bpo: 32173 .. date: 2017-12-04-10-14-23 .. nonce: e0C5dF .. section: Library

Add lazycache function to __all__.
Use dict.clear to clear the cache.
Refactoring getline function and checkcache function.

.. bpo: 17422 .. date: 2020-02-19-11-13-47 .. nonce: g7_9zz .. section: Documentation

The language reference now specifies restrictions on class namespaces. Adapted from a patch by Ethan Furman.

.. bpo: 39572 .. date: 2020-02-18-18-37-07 .. nonce: CCtzy1 .. section: Documentation

Updated documentation of total flag of TypedDict.

.. bpo: 39654 .. date: 2020-02-18-07-42-20 .. nonce: MoT1jI .. section: Documentation

In pyclbr doc, update 'class' to 'module' where appropriate and add readmodule comment. Patch by Hakan Çelik.

.. bpo: 39153 .. date: 2020-01-27-22-24-51 .. nonce: Pjl8jV .. section: Documentation

Clarify refcounting semantics for the following functions: - PyObject_SetItem - PyMapping_SetItemString - PyDict_SetItem - PyDict_SetItemString

.. bpo: 39392 .. date: 2020-01-27-18-18-42 .. nonce: oiqcLO .. section: Documentation

Explain that when filling with turtle, overlap regions may be left unfilled.

.. bpo: 39369 .. date: 2020-01-17-13-59-21 .. nonce: Bx5yE3 .. section: Documentation

Update mmap readline method description. The fact that the readline method does update the file position should not be ignored since this might give the impression for the programmer that it doesn't update it.

.. bpo: 9056 .. date: 2018-09-28-18-13-08 .. nonce: -sFOwU .. section: Documentation

Include subsection in TOC for PDF version of docs.

.. bpo: 38325 .. date: 2020-02-11-00-38-32 .. nonce: HgmfoE .. section: Tests

Skip tests on non-BMP characters of test_winconsoleio.

.. bpo: 39502 .. date: 2020-01-30-15-04-54 .. nonce: chbpII .. section: Tests

Skip test_zipfile.test_add_file_after_2107() if :func:time.localtime fails with :exc:OverflowError. It is the case on AIX 6.1 for example.

.. bpo: 39489 .. date: 2020-01-29-19-17-02 .. nonce: HKPzv- .. section: Build

Remove COUNT_ALLOCS special build.

.. bpo: 39553 .. date: 2020-02-04-19-50-53 .. nonce: _EnweA .. section: Windows

Delete unused code related to SxS manifests.

.. bpo: 39439 .. date: 2020-01-24-03-15-05 .. nonce: sFxGfR .. section: Windows

Honor the Python path when a virtualenv is active on Windows.

.. bpo: 39393 .. date: 2020-01-20-23-42-53 .. nonce: gWlJDG .. section: Windows

Improve the error message when attempting to load a DLL with unresolved dependencies.

.. bpo: 38883 .. date: 2020-01-11-22-53-55 .. nonce: X7FRaN .. section: Windows

:meth:~pathlib.Path.home and :meth:~pathlib.Path.expanduser on Windows now prefer :envvar:USERPROFILE and no longer use :envvar:HOME, which is not normally set for regular user accounts. This makes them again behave like :func:os.path.expanduser, which was changed to ignore :envvar:HOME in 3.8, see :issue:36264.

.. bpo: 39185 .. date: 2020-01-02-01-11-53 .. nonce: T4herN .. section: Windows

The build.bat script has additional options for very-quiet output (-q) and very-verbose output (-vv)

.. bpo: 39663 .. date: 2020-02-17-21-09-03 .. nonce: wexcsH .. section: IDLE

Add tests for pyparse find_good_parse_start().

.. bpo: 39600 .. date: 2020-02-10-17-09-48 .. nonce: X6NsyM .. section: IDLE

In the font configuration window, remove duplicated font names.

.. bpo: 30780 .. date: 2020-01-27-16-44-29 .. nonce: nR80qu .. section: IDLE

Add remaining configdialog tests for buttons and highlights and keys tabs.

.. bpo: 39388 .. date: 2020-01-25-02-26-45 .. nonce: x4TQNh .. section: IDLE

IDLE Settings Cancel button now cancels pending changes

.. bpo: 38792 .. date: 2019-11-13-23-51-39 .. nonce: xhTC5a .. section: IDLE

Close an IDLE shell calltip if a :exc:KeyboardInterrupt or shell restart occurs. Patch by Zackery Spytz.

.. bpo: 35081 .. date: 2020-02-12-21-38-49 .. nonce: 5tj1yC .. section: C API

Move the bytes_methods.h header file to the internal C API as pycore_bytes_methods.h: it only contains private symbols (prefixed by _Py), except of the PyDoc_STRVAR_shared() macro.

.. bpo: 35081 .. date: 2020-02-12-21-24-02 .. nonce: at7BjN .. section: C API

Move the dtoa.h header file to the internal C API as pycore_dtoa.h: it only contains private functions (prefixed by _Py). The :mod:math and :mod:cmath modules must now be compiled with the Py_BUILD_CORE macro defined.

.. bpo: 39573 .. date: 2020-02-07-10-41-53 .. nonce: EG9VDI .. section: C API

Add :c:func:Py_SET_SIZE function to set the size of an object.

.. bpo: 39500 .. date: 2020-02-07-09-35-43 .. nonce: xRAEgX .. section: C API

:c:func:PyUnicode_IsIdentifier does not call :c:func:Py_FatalError anymore if the string is not ready.

.. bpo: 39573 .. date: 2020-02-07-03-39-03 .. nonce: Oa8cL1 .. section: C API

Add :c:func:Py_SET_TYPE function to set the type of an object.

.. bpo: 39573 .. date: 2020-02-07-00-23-44 .. nonce: nRD1q7 .. section: C API

Add a :c:func:Py_SET_REFCNT function to set the reference counter of an object.

.. bpo: 39542 .. date: 2020-02-05-13-14-20 .. nonce: 5mleGX .. section: C API

Convert :c:func:PyType_HasFeature, :c:func:PyType_Check and :c:func:PyType_CheckExact macros to static inline functions.

.. bpo: 39542 .. date: 2020-02-05-12-40-51 .. nonce: si-_Zq .. section: C API

In the limited C API, PyObject_INIT() and PyObject_INIT_VAR() are now defined as aliases to :c:func:PyObject_Init and :c:func:PyObject_InitVar to make their implementation opaque. It avoids to leak implementation details in the limited C API. Exclude the following functions from the limited C API: _Py_NewReference(), _Py_ForgetReference(), _PyTraceMalloc_NewReference() and _Py_GetRefTotal().

.. bpo: 39542 .. date: 2020-02-05-12-00-18 .. nonce: RJCUKR .. section: C API

Exclude trashcan mechanism from the limited C API: it requires access to PyTypeObject and PyThreadState structure fields, whereas these structures are opaque in the limited C API.

.. bpo: 39511 .. date: 2020-01-31-16-35-21 .. nonce: nv9yEn .. section: C API

The :c:func:PyThreadState_Clear function now calls the :c:member:PyThreadState.on_delete callback. Previously, that happened in :c:func:PyThreadState_Delete.

.. bpo: 38076 .. date: 2020-01-17-11-37-05 .. nonce: cxfw2x .. section: C API

Fix to clear the interpreter state only after clearing module globals to guarantee module state access from C Extensions during runtime destruction

.. bpo: 39245 .. date: 2020-01-07-13-46-40 .. nonce: G7wog6 .. section: C API

The Vectorcall API (PEP 590) was made public, adding the functions PyObject_Vectorcall, PyObject_VectorcallMethod, PyVectorcall_Function, PyObject_CallOneArg, PyObject_CallMethodNoArgs, PyObject_CallMethodOneArg, PyObject_FastCallDict, and the flag Py_TPFLAGS_HAVE_VECTORCALL.