3.10.0a5.rst

Avoid static buffers when computing the repr of :class:`ctypes.c_double` and :class:`ctypes.c_longdouble` values.

Refactor the PyEval_ family of functions.

• An new function _PyEval_Vector is added to simplify calls to Python from C.
• _PyEval_EvalCodeWithName is removed
• PyEval_EvalCodeEx is retained as part of the API, but is not used internally

Replace :c:func:`Py_FatalError` calls in the compiler with regular :exc:`SystemError` exceptions. Patch by Victor Stinner.

Improve error message for missing ":" before blocks. Patch by Pablo Galindo.

Improve error message in the parser when using un-parenthesised tuples in comprehensions. Patch by Pablo Galindo.

Fix parser crash when reporting syntax errors in f-string with newlines. Patch by Pablo Galindo.

Syntax errors for unterminated string literals now point to the start of the string instead of reporting EOF/EOL.

The inline cache for LOAD_ATTR now also optimizes access to attributes defined by __slots__. This makes reading such attribute up to 30% faster.

Improve error messages in the parser when parentheses are not closed. Patch by Pablo Galindo.

Fix bytearray repetition incorrectly copying data from the start of the buffer, even if the data is offset within the buffer (e.g. after reassigning a slice at the start of the bytearray to a shorter byte string).

Fix the :c:func:`!_PyUnicode_FromId` function (_Py_IDENTIFIER(var) API) when :c:func:`Py_Initialize` / :c:func:`Py_Finalize` is called multiple times: preserve _PyRuntime.unicode_ids.next_index value.

Fix a crash when working out the error line of a :exc:`SyntaxError` in some multi-line expressions.

frame.f_lineno is correct even if frame.f_trace is set to True

Remove deprecated aliases to :ref:`collections-abstract-base-classes` from the :mod:`collections` module.

Fixed possible leak in import when sys.modules is not a dict.

In string formatting, preceding the width field by '0' no longer affects the default alignment for strings.

Fixed a reference leak in the :mod:`curses` module. Patch by Pablo Galindo

Update the bundled pip to 21.0.1 and setuptools to 52.0.0.

Deprecate distutils in documentation and add warning on import.

Improve performance of :mod:`tokenize` by 20-30%. Patch by Anthony Sottile.

Fix :func:`math.nextafter` for NaN on AIX.

Add :data:`sys.stdlib_module_names`, containing the list of the standard library module names. Patch by Victor Stinner.

Fix random.Random.sample when counts argument is not None.

Use :class:`~traceback.TracebackException`'s new compact param in :class:`~unittest.TestResult` to reduce time and memory consumed by traceback formatting.

Add :func:`randbytes` to random.__all__.

[Enum] Flags consisting of a single bit are now considered canonical, and will be the only flags returned from listing and iterating over a Flag class or a Flag member. Multi-bit flags are considered aliases; they will be returned from lookups and operations that result in their value. Iteration for both Flag and Flag members is in definition order.

Added the compact parameter to the constructor of :class:`traceback.TracebackException` to reduce time and memory for use cases that only need to call :func:`TracebackException.format` and :func:`TracebackException.format_exception_only`.

The :c:func:`Py_FatalError` function and the :mod:`faulthandler` module now dump the list of extension modules on a fatal error.

Removed recursion from :class:`~traceback.TracebackException` to allow it to handle long exception chains.

[Enum] move member creation from EnumMeta.__new__ to _proto_member.__set_name__, allowing members to be created and visible in __init_subclass__.

Fix os.set_inheritable() for O_PATH file descriptors on Linux.

Fix a reference leak in the getcodec() function of CJK codecs. Patch by Victor Stinner.

Convert the 6 CJK codec extension modules (_codecs_cn, _codecs_hk, _codecs_iso2022, _codecs_jp, _codecs_kr and _codecs_tw) to the multiphase initialization API (PEP 489). Patch by Victor Stinner.

remove __init_subclass__ support for Enum members

Make internal caches of the _json module compatible with subinterpreters.

Fix HTMLParser parsing rules for element attributes containing commas with spaces. Patch by Karl Dubost.

Require SQLite 3.7.15 or newer. Patch by Erlend E. Aasland.

Convert the _multibytecodec extension module (CJK codecs) to multi-phase initialization (PEP 489). Patch by Erlend E. Aasland.

The distutils bdist_wininst command deprecated in Python 3.8 has been removed. The distutils bdist_wheel command is now recommended to distribute binary packages on Windows.

The undocumented built-in function sqlite3.enable_shared_cache is now deprecated, scheduled for removal in Python 3.12. Its use is strongly discouraged by the SQLite3 documentation. Patch by Erlend E. Aasland.

Make pdb populate sys.path[0] exactly the same as regular python execution.

Fix pdb: previously pdb would fail to restart the debugging target if it was specified using a relative path and the current directory changed.

Fix CLI of :mod:`cProfile` and :mod:`profile` to catch :exc:`BrokenPipeError`.

Don't decrement the reference count of the previous user_ptr when set_panel_userptr fails.

Allow executing callables that have a boolean value of False when passed to :class:`Threading.thread` as the target. Patch contributed by Barney Stratford.

Add an 'end_lineno' attribute to the Class and Function objects that appear in the tree returned by pyclbr functions. This and the existing 'lineno' attribute define the extent of class and def statements. Patch by Aviral Srivastava.

The BUTTON5_* constants are now exposed in the :mod:`curses` module if available.

Correct call to :mod:`tkinter.colorchooser` to return RGB triplet of ints instead of floats. Patch by Cheryl Sabella.

Fix doc for type(name, bases, dict). Patch by Boris Verkhovskiy and Éric Araujo.

Updated importlib.util.resolve_name() doc to use __spec__.parent instead of __package__. (Thanks Yair Frid.)

Use :meth:`unittest.TestLoader().loadTestsFromTestCase` instead of :meth:`unittest.makeSuite` in :mod:`sqlite3` tests. Patch by Erlend E. Aasland.

In :mod:`sqlite3`, fix CheckTraceCallbackContent for SQLite pre 3.7.15.

Pass --timeout=$(TESTTIMEOUT) option to the default profile task ./python -m test --pgo command.

make regen-all now also runs regen-keyword. Patch by Victor Stinner.

Removed the grep -q and -E flags in the tzpath validation section of the configure script to better accommodate users of some platforms (specifically Solaris 10).

Add library search path by wr-cc in add_cross_compiling_paths() for VxWorks.

Add --with-wheel-pkg-dir=PATH option to the ./configure script. If specified, the :mod:`ensurepip` module looks for setuptools and pip wheel packages in this directory: if both are present, these wheel packages are used instead of ensurepip bundled wheel packages.

Some Linux distribution packaging policies recommend against bundling dependencies. For example, Fedora installs wheel packages in the /usr/share/python-wheels/ directory and don't install the ensurepip._bundled package.

Updated Windows installer to include OpenSSL 1.1.1i

Upgrade Windows installer to use SQLite 3.34.0.

Ensure that the value of sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET') is always a string, even in when the value is parsable as an integer.

Make IDLE invoke :func:`sys.excepthook` in normal, 2-process mode. Patch by Ken Hilton.

Fix problem debugging user classes with __repr__ method.

Disable Debug=>Stack Viewer when user code is running or Debugger is active, to prevent hang or crash. Patch by Zackery Spytz.

Finish zzdummy example extension module: make menu entries work; add docstrings and tests with 100% coverage.

When Python is built in debug mode (with C assertions), calling a type slot like sq_length (__len__() in Python) now fails with a fatal error if the slot succeeded with an exception set, or failed with no exception set. The error message contains the slot, the type name, and the current exception (if an exception is set). Patch by Victor Stinner.

Fixed a compiler warning in :c:func:`Py_UNICODE_ISSPACE()` on platforms with signed :c:type:`wchar_t`.