3.9.0b1 - Cpython — ContextQMD

.. bpo: 40501 .. date: 2020-05-06-00-41-11 .. nonce: 61wv .. release date: 2020-05-19 .. section: Security

:mod:uuid no longer uses :mod:ctypes to load :file:libuuid or :file:rpcrt4.dll at runtime.

.. bpo: 40663 .. date: 2020-05-17-20-38-12 .. nonce: u2aiZf .. section: Core and Builtins

Correctly generate annotations where parentheses are omitted but required (e.g: Type[(str, int, *other))].

.. bpo: 40596 .. date: 2020-05-11-20-53-52 .. nonce: dwOH_X .. section: Core and Builtins

Fixed :meth:str.isidentifier for non-canonicalized strings containing non-BMP characters on Windows.

.. bpo: 40593 .. date: 2020-05-11-13-50-52 .. nonce: yuOXj3 .. section: Core and Builtins

Improved syntax errors for invalid characters in source code.

.. bpo: 40585 .. date: 2020-05-11-00-19-42 .. nonce: yusknY .. section: Core and Builtins

Fixed a bug when using :func:codeop.compile_command that was causing exceptions to be swallowed with the new parser. Patch by Pablo Galindo

.. bpo: 40566 .. date: 2020-05-09-01-39-16 .. nonce: wlcjW_ .. section: Core and Builtins

Apply :pep:573 to :mod:abc.

.. bpo: 40502 .. date: 2020-05-08-03-25-26 .. nonce: e-VCyL .. section: Core and Builtins

Initialize n->n_col_offset. (Patch by Joannah Nanjekye)

.. bpo: 40527 .. date: 2020-05-06-14-52-35 .. nonce: gTNKuy .. section: Core and Builtins

Fix command line argument parsing: no longer write errors multiple times into stderr.

.. bpo: 1635741 .. date: 2020-05-05-21-11-35 .. nonce: ggwD3C .. section: Core and Builtins

Port :mod:errno to multiphase initialization (:pep:489).

.. bpo: 40523 .. date: 2020-05-05-20-36-15 .. nonce: hKZVTB .. section: Core and Builtins

Add pass-throughs for :func:hash and :func:reversed to :class:weakref.proxy objects. Patch by Pablo Galindo.

.. bpo: 1635741 .. date: 2020-05-05-03-36-27 .. nonce: ARv1YV .. section: Core and Builtins

Port :mod:syslog to multiphase initialization (:pep:489).

.. bpo: 40246 .. date: 2020-05-03-23-28-11 .. nonce: c1D7x8 .. section: Core and Builtins

Reporting a specialised error message for invalid string prefixes, which was introduced in :issue:40246, is being reverted due to backwards compatibility concerns for strings that immediately follow a reserved keyword without whitespace between them. Constructs like bg="#d00" if clear else"#fca" were failing to parse, which is not an acceptable breakage on such short notice.

.. bpo: 40417 .. date: 2020-05-01-19-04-52 .. nonce: Sti2lJ .. section: Core and Builtins

Fix imp module deprecation warning when PyImport_ReloadModule is called. Patch by Robert Rouhani.

.. bpo: 40408 .. date: 2020-05-01-15-36-14 .. nonce: XzQI59 .. section: Core and Builtins

Fixed support of nested type variables in GenericAlias (e.g. list[list[T]]).

.. bpo: 1635741 .. date: 2020-04-30-01-44-42 .. nonce: GKtjqr .. section: Core and Builtins

Port _stat module to multiphase initialization (:pep:489).

.. bpo: 29587 .. date: 2020-04-30-00-50-25 .. nonce: oEwSq .. section: Core and Builtins

Enable implicit exception chaining when calling :meth:generator.throw.

.. bpo: 40328 .. date: 2020-04-19-22-23-32 .. nonce: gWJ53f .. section: Core and Builtins

Add tools for generating mappings headers for CJKCodecs.

.. bpo: 40228 .. date: 2020-04-08-17-02-35 .. nonce: bRaaJ- .. section: Core and Builtins

Setting frame.f_lineno is now robust w.r.t. changes in the source-to-bytecode compiler

.. bpo: 38880 .. date: 2019-11-22-14-34-47 .. nonce: evcCPa .. section: Core and Builtins

Added the ability to list interpreters associated with channel ends in the internal subinterpreters module.

.. bpo: 37986 .. date: 2019-11-20-09-50-58 .. nonce: o0lmA7 .. section: Core and Builtins

Improve performance of :c:func:PyLong_FromDouble for values that fit into :c:expr:long.

.. bpo: 40662 .. date: 2020-05-18-12-56-45 .. nonce: dfornR .. section: Library

Fixed :func:ast.get_source_segment for ast nodes that have incomplete location information. Patch by Irit Katriel.

.. bpo: 40665 .. date: 2020-05-17-21-56-38 .. nonce: msB7u5 .. section: Library

Convert :mod:bisect to use Argument Clinic.

.. bpo: 40536 .. date: 2020-05-17-14-00-12 .. nonce: FCpoRA .. section: Library

Added the :func:~zoneinfo.available_timezones function to the :mod:zoneinfo module. Patch by Paul Ganssle.

.. bpo: 40645 .. date: 2020-05-16-19-34-38 .. nonce: 7ibMt- .. section: Library

The :class:hmac.HMAC exposes internal implementation details. The attributes digest_cons, inner, and outer are deprecated and will be removed in the future.

.. bpo: 40645 .. date: 2020-05-16-17-05-02 .. nonce: wYSkjT .. section: Library

The internal module _hashlib wraps and exposes OpenSSL's HMAC API. The new code will be used in Python 3.10 after the internal implementation details of the pure Python HMAC module are no longer part of the public API.

.. bpo: 40637 .. date: 2020-05-15-21-57-10 .. nonce: lb3Bnp .. section: Library

Builtin hash modules can now be disabled or selectively enabled with configure --with-builtin-hashlib-hashes=sha3,blake1 or --without-builtin-hashlib-hashes.

.. bpo: 37630 .. date: 2020-05-15-19-53-18 .. nonce: O5kgAw .. section: Library

The :mod:hashlib module can now use SHA3 hashes and SHAKE XOF from OpenSSL when available.

.. bpo: 40479 .. date: 2020-05-15-17-38-21 .. nonce: yamSCh .. section: Library

The :mod:hashlib now compiles with OpenSSL 3.0.0-alpha2.

.. bpo: 40257 .. date: 2020-05-13-23-10-25 .. nonce: aR4TGp .. section: Library

Revert changes to :func:inspect.getdoc.

.. bpo: 40607 .. date: 2020-05-13-15-32-13 .. nonce: uSPFCi .. section: Library

When cancelling a task due to timeout, :meth:asyncio.wait_for will now propagate the exception if an error happens during cancellation. Patch by Roman Skurikhin.

.. bpo: 40612 .. date: 2020-05-13-10-23-29 .. nonce: gOIreM .. section: Library

Fix edge cases in SyntaxError formatting. If the offset is <= 0, no caret is printed. If the offset is > line length, the caret is printed pointing just after the last character.

.. bpo: 40597 .. date: 2020-05-11-19-17-23 .. nonce: 4SGfgm .. section: Library

If text content lines are longer than policy.max_line_length, always use a content-encoding to make sure they are wrapped.

.. bpo: 40571 .. date: 2020-05-09-15-38-25 .. nonce: kOXZGC .. section: Library

Added functools.cache() as a simpler, more discoverable way to access the unbounded cache variant of lru_cache(maxsize=None).

.. bpo: 40503 .. date: 2020-05-08-15-48-39 .. nonce: elZyxc .. section: Library

:pep:615, the :mod:zoneinfo module. Adds support for the IANA time zone database.

.. bpo: 40397 .. date: 2020-05-07-21-22-04 .. nonce: PVWFAn .. section: Library

Removed attributes __args__ and __parameters__ from special generic aliases like typing.List (not subscripted).

.. bpo: 40549 .. date: 2020-05-07-20-11-51 .. nonce: 6FiRSV .. section: Library

Convert posixmodule.c ("posix" or "nt" module) to the multiphase initialization (PEP 489).

.. bpo: 31033 .. date: 2020-05-07-06-41-20 .. nonce: waCj3n .. section: Library

Add a msg argument to :meth:Future.cancel and :meth:Task.cancel.

.. bpo: 40541 .. date: 2020-05-06-15-36-47 .. nonce: LlYghL .. section: Library

Added an optional counts parameter to random.sample().

.. bpo: 40515 .. date: 2020-05-06-13-51-19 .. nonce: TUCvYB .. section: Library

The :mod:ssl and :mod:hashlib modules now actively check that OpenSSL is build with thread support. Python 3.7.0 made thread support mandatory and no longer works safely with a no-thread builds.

.. bpo: 31033 .. date: 2020-05-06-02-33-00 .. nonce: aX12pw .. section: Library

When a :class:asyncio.Task is cancelled, the exception traceback now chains all the way back to where the task was first interrupted.

.. bpo: 40504 .. date: 2020-05-05-17-12-47 .. nonce: EX6wPn .. section: Library

:func:functools.lru_cache objects can now be the targets of weakrefs.

.. bpo: 40559 .. date: 2020-05-05-08-12-51 .. nonce: 112wwa .. section: Library

Fix possible memory leak in the C implementation of :class:asyncio.Task.

.. bpo: 40480 .. date: 2020-05-04-21-21-43 .. nonce: mjldWa .. section: Library

fnmatch.fnmatch() could take exponential time in the presence of multiple * pattern characters. This was repaired by generating more elaborate regular expressions to avoid futile backtracking.

.. bpo: 40495 .. date: 2020-05-04-11-20-49 .. nonce: TyTc2O .. section: Library

:mod:compileall is now able to use hardlinks to prevent duplicates in a case when .pyc files for different optimization levels have the same content.

.. bpo: 40457 .. date: 2020-05-02-17-17-37 .. nonce: EXReI1 .. section: Library

The ssl module now support OpenSSL builds without TLS 1.0 and 1.1 methods.

.. bpo: 40355 .. date: 2020-05-02-14-24-48 .. nonce: xTujaB .. section: Library

Improve error reporting in :func:ast.literal_eval in the presence of malformed :class:ast.Dict nodes instead of silently ignoring any non-conforming elements. Patch by Curtis Bucher.

.. bpo: 40465 .. date: 2020-05-02-12-00-28 .. nonce: qfCjOD .. section: Library

Deprecated the optional random argument to random.shuffle().

.. bpo: 40459 .. date: 2020-05-02-04-29-31 .. nonce: fSAYVD .. section: Library

:func:platform.win32_ver now produces correct ptype strings instead of empty strings.

.. bpo: 39435 .. date: 2020-05-01-23-24-25 .. nonce: mgb6ib .. section: Library

The first argument of :func:pickle.loads is now positional-only.

.. bpo: 39305 .. date: 2020-05-01-00-22-58 .. nonce: Cuwu_H .. section: Library

Update :mod:!nntplib to merge :class:!nntplib.NNTP and :class:!nntplib._NNTPBase. Patch by Donghee Na.

.. bpo: 32494 .. date: 2020-04-30-22-25-08 .. nonce: 1xaU5l .. section: Library

Update :mod:dbm.gnu to use gdbm_count if possible when calling :func:len. Patch by Donghee Na.

.. bpo: 40453 .. date: 2020-04-30-22-04-58 .. nonce: ggz7sl .. section: Library

Add isolated=True keyword-only parameter to _xxsubinterpreters.create(). An isolated subinterpreter cannot spawn threads, spawn a child process or call os.fork().

.. bpo: 40286 .. date: 2020-04-29-18-02-16 .. nonce: txbQNx .. section: Library

Remove _random.Random.randbytes(): the C implementation of randbytes(). Implement the method in Python to ease subclassing: randbytes() now directly reuses getrandbits().

.. bpo: 40394 .. date: 2020-04-28-18-59-48 .. nonce: Yi5uuM .. section: Library

Added default arguments to :meth:difflib.SequenceMatcher.find_longest_match.

.. bpo: 39995 .. date: 2020-04-28-18-25-27 .. nonce: WmA3Gk .. section: Library

Fix a race condition in concurrent.futures._ThreadWakeup: access to _ThreadWakeup is now protected with the shutdown lock.

.. bpo: 30966 .. date: 2020-04-27-20-27-39 .. nonce: Xmtlqu .. section: Library

Process.shutdown(wait=True) of :mod:concurrent.futures now closes explicitly the result queue.

.. bpo: 30966 .. date: 2020-04-27-17-19-09 .. nonce: _5lDx- .. section: Library

Add a new :meth:~multiprocessing.SimpleQueue.close method to the :class:~multiprocessing.SimpleQueue class to explicitly close the queue.

.. bpo: 39966 .. date: 2020-04-27-14-48-43 .. nonce: N5yXUe .. section: Library

Revert bpo-25597. :class:unittest.mock.MagicMock with wraps' set uses default return values for magic methods.

.. bpo: 39791 .. date: 2020-04-27-00-51-40 .. nonce: wv8Dxn .. section: Library

Added files() function to importlib.resources with support for subdirectories in package data, matching backport in importlib_resources 1.5.

.. bpo: 40375 .. date: 2020-04-25-23-14-11 .. nonce: 5GuK2A .. section: Library

:meth:imaplib.IMAP4.unselect is added. Patch by Donghee Na.

.. bpo: 40389 .. date: 2020-04-25-20-00-58 .. nonce: FPA6f0 .. section: Library

repr() now returns typing.Optional[T] when called for typing.Union of two types, one of which is NoneType.

.. bpo: 40291 .. date: 2020-04-14-22-31-27 .. nonce: _O8hXn .. section: Library

Add support for CAN_J1939 sockets (available on Linux 5.4+)

.. bpo: 40273 .. date: 2020-04-14-09-54-35 .. nonce: IN73Ks .. section: Library

:class:types.MappingProxyType is now reversible.

.. bpo: 39075 .. date: 2020-04-07-23-44-06 .. nonce: hgck3j .. section: Library

The repr for :class:types.SimpleNamespace is now insertion ordered rather than alphabetical.

.. bpo: 40192 .. date: 2020-04-05-04-16-14 .. nonce: nk8uRJ .. section: Library

On AIX, :func:~time.thread_time is now implemented with thread_cputime() which has nanosecond resolution, rather than clock_gettime(CLOCK_THREAD_CPUTIME_ID) which has a resolution of 10 milliseconds. Patch by Batuhan Taskaya.

.. bpo: 40025 .. date: 2020-03-21-05-26-38 .. nonce: DTLtyq .. section: Library

Raise TypeError when generate_next_value is defined after members. Patch by Ethan Onstott.

.. bpo: 39058 .. date: 2019-12-15-19-17-10 .. nonce: 7ci-vd .. section: Library

In the argparse module, the repr for Namespace() and other argument holders now displayed in the order attributes were added. Formerly, it displayed in alphabetical order even though argument order is preserved the user visible parts of the module.

.. bpo: 24416 .. date: 2019-09-01-15-17-49 .. nonce: G8Ww1U .. section: Library

The isocalendar() methods of :class:datetime.date and :class:datetime.datetime now return a :term:named tuple instead of a :class:tuple.

.. bpo: 34790 .. date: 2020-05-08-20-18-55 .. nonce: t6kW_1 .. section: Documentation

Add version of removal for explicit passing of coros to asyncio.wait()'s documentation

.. bpo: 40561 .. date: 2020-05-08-08-39-40 .. nonce: ZMB_2i .. section: Documentation

Provide docstrings for webbrowser open functions.

.. bpo: 40499 .. date: 2020-05-04-14-20-02 .. nonce: tjLSo8 .. section: Documentation

Mention that :func:asyncio.wait requires a non-empty set of awaitables.

.. bpo: 39705 .. date: 2020-03-14-18-37-06 .. nonce: nQVqig .. section: Documentation

Tutorial example for sorted() in the Loop Techniques section is given a better explanation. Also a new example is included to explain sorted()'s basic behavior.

.. bpo: 39435 .. date: 2020-01-24-05-42-57 .. nonce: EFcdFU .. section: Documentation

Fix an incorrect signature for :func:pickle.loads in the docs

.. bpo: 40055 .. date: 2020-05-15-01-21-44 .. nonce: Xp4aP9 .. section: Tests

distutils.tests now saves/restores warnings filters to leave them unchanged. Importing tests imports docutils which imports pkg_resources which adds a warnings filter.

.. bpo: 40436 .. date: 2020-04-29-16-08-24 .. nonce: gDMnYl .. section: Tests

test_gdb and test.pythoninfo now check gdb command exit code.

.. bpo: 40653 .. date: 2020-05-17-03-33-00 .. nonce: WI8UGn .. section: Build

Move _dirnameW out of HAVE_SYMLINK to fix a potential compiling issue.

.. bpo: 40514 .. date: 2020-05-05-15-39-11 .. nonce: bZZmuS .. section: Build

Add --with-experimental-isolated-subinterpreters build option to configure: better isolate subinterpreters, experimental build mode.

.. bpo: 40650 .. date: 2020-05-17-00-08-13 .. nonce: 4euMtU .. section: Windows

Include winsock2.h in pytime.c for timeval.

.. bpo: 40458 .. date: 2020-05-01-20-57-57 .. nonce: Eb0ueI .. section: Windows

Increase reserved stack space to prevent overflow crash on Windows.

.. bpo: 39148 .. date: 2020-03-23-19-07-55 .. nonce: W1YJEb .. section: Windows

Add IPv6 support to :mod:asyncio datagram endpoints in ProactorEventLoop. Change the raised exception for unknown address families to ValueError as it's not coming from Windows API.

.. bpo: 34956 .. date: 2020-05-18-02-43-11 .. nonce: 35IcGF .. section: macOS

When building Python on macOS from source, _tkinter now links with non-system Tcl and Tk frameworks if they are installed in /Library/Frameworks, as had been the case on older releases of macOS. If a macOS SDK is explicitly configured, by using --enable-universalsdk= or -isysroot, only the SDK itself is searched. The default behavior can still be overridden with --with-tcltk-includes and --with-tcltk-libs.

.. bpo: 35569 .. date: 2020-04-15-00-02-47 .. nonce: 02_1MV .. section: macOS

Expose RFC 3542 IPv6 socket options.

.. bpo: 40479 .. date: 2020-05-15-17-48-25 .. nonce: B1gBl- .. section: Tools/Demos

Update multissltest helper to test with latest OpenSSL 1.0.2, 1.1.0, 1.1.1, and 3.0.0-alpha.

.. bpo: 40431 .. date: 2020-04-29-01-32-17 .. nonce: B_aEZ0 .. section: Tools/Demos

Fix a syntax typo in turtledemo that now raises a SyntaxError.

.. bpo: 40163 .. date: 2020-04-03-08-32-31 .. nonce: lX8K4B .. section: Tools/Demos

Fix multissltest tool. OpenSSL has changed download URL for old releases. The multissltest tool now tries to download from current and old download URLs.

.. bpo: 39465 .. date: 2020-05-14-00-36-19 .. nonce: 3a5g-X .. section: C API

Remove the _PyUnicode_ClearStaticStrings() function from the C API.

.. bpo: 38787 .. date: 2020-05-10-16-39-08 .. nonce: XzQ59O .. section: C API

Add PyCFunction_CheckExact() macro for exact type checks now that we allow subtypes of PyCFunction, as well as PyCMethod_CheckExact() and PyCMethod_Check() for the new PyCMethod subtype.

.. bpo: 40545 .. date: 2020-05-07-11-41-13 .. nonce: 51DzF1 .. section: C API

Declare _PyErr_GetTopmostException() with PyAPI_FUNC() to properly export the function in the C API. The function remains private (_Py) prefix.

.. bpo: 40412 .. date: 2020-05-01-17-28-04 .. nonce: dE0D8N .. section: C API

Nullify inittab_copy during finalization, preventing future interpreter initializations in an embedded situation from crashing. Patch by Gregory Szorc.

.. bpo: 40429 .. date: 2020-04-29-01-39-41 .. nonce: VQfvta .. section: C API

The :c:func:PyThreadState_GetFrame function now returns a strong reference to the frame.

.. bpo: 40428 .. date: 2020-04-28-23-17-27 .. nonce: rmtpru .. section: C API

Remove the following functions from the C API. Call :c:func:PyGC_Collect explicitly to free all free lists.

PyAsyncGen_ClearFreeLists()
PyContext_ClearFreeList()
PyDict_ClearFreeList()
PyFloat_ClearFreeList()
PyFrame_ClearFreeList()
PyList_ClearFreeList()
PySet_ClearFreeList()
PyTuple_ClearFreeList()

.. bpo: 40421 .. date: 2020-04-28-19-29-36 .. nonce: 3uIIaB .. section: C API

New :c:func:PyFrame_GetBack function: get the frame next outer frame.

.. bpo: 40421 .. date: 2020-04-28-15-47-58 .. nonce: ZIzOV0 .. section: C API

New :c:func:PyFrame_GetCode function: return a borrowed reference to the frame code.

.. bpo: 40217 .. date: 2020-04-27-14-00-38 .. nonce: sgn6c8 .. section: C API

Ensure that instances of types created with :c:func:PyType_FromSpecWithBases will visit its class object when traversing references in the garbage collector (implemented as an extension of the provided :c:member:~PyTypeObject.tp_traverse). Patch by Pablo Galindo.

.. bpo: 38787 .. date: 2020-01-22-12-38-59 .. nonce: HUH6hd .. section: C API

Module C state is now accessible from C-defined heap type methods (:pep:573). Patch by Marcel Plch and Petr Viktorin.