+++++++++++
Python News
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What's New in Python next?
==========================

Release date: XXXX-XX-XX

Core and Builtins
-----------------

- bpo-28856: Fix an oversight that %b format for bytes should support objects
  follow the buffer protocol.

- bpo-29723: The ``sys.path[0]`` initialization change for bpo-29139 caused a
  regression by revealing an inconsistency in how sys.path is initialized when
  executing ``__main__`` from a zipfile, directory, or other import location.
  The interpreter now consistently avoids ever adding the import location's
  parent directory to ``sys.path``, and ensures no other ``sys.path`` entries
  are inadvertently modified when inserting the import location named on the
  command line.

- bpo-29568: Escaped percent "%%" in the format string for classic string
  formatting no longer allows any characters between two percents.

- bpo-29714: Fix a regression that bytes format may fail when containing zero
  bytes inside.

- bpo-29695: bool(), float(), list() and tuple() no longer take keyword arguments.
  The first argument of int() can now be passes only as positional argument.

- bpo-20087: Prefer glibc's list of locale aliases to the X11 ones.

- bpo-28893: Set correct __cause__ for errors about invalid awaitables
  returned from __aiter__ and __anext__.

- bpo-29683: Fixes to memory allocation in _PyCode_SetExtra.  Patch by
  Brian Coleman.

- bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords.
  It should raise TypeError when kwargs is not a dict.  But it might
  cause segv when args=NULL and kwargs is not a dict.

- bpo-28598: Support __rmod__ for subclasses of str being called before
  str.__mod__.  Patch by Martijn Pieters.

- bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX.
  Patch by Matthieu Dartiailh.

- bpo-29602: Fix incorrect handling of signed zeros in complex constructor for
  complex subclasses and for inputs having a __complex__ method. Patch
  by Serhiy Storchaka.

- bpo-29347: Fixed possibly dereferencing undefined pointers
  when creating weakref objects.

- bpo-29463: Add ``docstring`` field to Module, ClassDef, FunctionDef,
  and AsyncFunctionDef ast nodes.  docstring is not first stmt in their body
  anymore.  It affects ``co_firstlineno`` and ``co_lnotab`` of code object
  for module and class.

- bpo-29438: Fixed use-after-free problem in key sharing dict.

- bpo-29546: Set the 'path' and 'name' attribute on ImportError for ``from ... import ...``.

- bpo-29546: Improve from-import error message with location

- Issue #29319: Prevent RunMainFromImporter overwriting sys.path[0].

- Issue #29337: Fixed possible BytesWarning when compare the code objects.
  Warnings could be emitted at compile time.

- Issue #29327: Fixed a crash when pass the iterable keyword argument to
  sorted().

- Issue #29034: Fix memory leak and use-after-free in os module (path_converter).

- Issue #29159: Fix regression in bytes(x) when x.__index__() raises Exception.

- Issue #29049: Call _PyObject_GC_TRACK() lazily when calling Python function.
  Calling function is up to 5% faster.

- Issue #28927: bytes.fromhex() and bytearray.fromhex() now ignore all ASCII
  whitespace, not only spaces.  Patch by Robert Xiao.

- Issue #28932: Do not include <sys/random.h> if it does not exist.

- Issue #25677: Correct the positioning of the syntax error caret for
  indented blocks.  Based on patch by Michael Layzell.

- Issue #29000: Fixed bytes formatting of octals with zero padding in alternate
  form.

- Issue #18896: Python function can now have more than 255 parameters.
  collections.namedtuple() now supports tuples with more than 255 elements.

- Issue #28596: The preferred encoding is UTF-8 on Android. Patch written by
  Chi Hsuan Yen.

- Issue #26919: On Android, operating system data is now always encoded/decoded
  to/from UTF-8, instead of the locale encoding to avoid inconsistencies with
  os.fsencode() and os.fsdecode() which are already using UTF-8.

- Issue #28991:  functools.lru_cache() was susceptible to an obscure reentrancy
  bug triggerable by a monkey-patched len() function.

- Issue #28147: Fix a memory leak in split-table dictionaries: setattr()
  must not convert combined table into split table. Patch written by INADA
  Naoki.

- Issue #28739: f-string expressions are no longer accepted as docstrings and
  by ast.literal_eval() even if they do not include expressions.

- Issue #28512: Fixed setting the offset attribute of SyntaxError by
  PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

- Issue #28918: Fix the cross compilation of xxlimited when Python has been
  built with Py_DEBUG defined.

- Issue #23722: Rather than silently producing a class that doesn't support
  zero-argument ``super()`` in methods, failing to pass the new
  ``__classcell__`` namespace entry up to ``type.__new__`` now results in a
  ``DeprecationWarning`` and a class that supports zero-argument ``super()``.

- Issue #28797: Modifying the class __dict__ inside the __set_name__ method of
  a descriptor that is used inside that class no longer prevents calling the
  __set_name__ method of other descriptors.

- Issue #28799: Remove the ``PyEval_GetCallStats()`` function and deprecate
  the untested and undocumented ``sys.callstats()`` function. Remove the
  ``CALL_PROFILE`` special build: use the :func:`sys.setprofile` function,
  :mod:`cProfile` or :mod:`profile` to profile function calls.

- Issue #12844: More than 255 arguments can now be passed to a function.

- Issue #28782: Fix a bug in the implementation ``yield from`` when checking
  if the next instruction is YIELD_FROM. Regression introduced by WORDCODE
  (issue #26647).

- Issue #28774: Fix error position of the unicode error in ASCII and Latin1
  encoders when a string returned by the error handler contains multiple
  non-encodable characters (non-ASCII for the ASCII codec, characters out
  of the U+0000-U+00FF range for Latin1).

- Issue #28731: Optimize _PyDict_NewPresized() to create correct size dict.
  Improve speed of dict literal with constant keys up to 30%.

- Issue #28532: Show sys.version when -V option is supplied twice.

- Issue #27100: The with-statement now checks for __enter__ before it
  checks for __exit__.  This gives less confusing error messages when
  both methods are missing. Patch by Jonathan Ellington.

- Issue #28746: Fix the set_inheritable() file descriptor method on platforms
  that do not have the ioctl FIOCLEX and FIONCLEX commands.

- Issue #26920: Fix not getting the locale's charset upon initializing the
  interpreter, on platforms that do not have langinfo.

- Issue #28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS X
  when decode astral characters.  Patch by Xiang Zhang.

- Issue #28665: Improve speed of the STORE_DEREF opcode by 40%.

- Issue #19398: Extra slash no longer added to sys.path components in case of
  empty compile-time PYTHONPATH components.

- Issue #28621: Sped up converting int to float by reusing faster bits counting
  implementation.  Patch by Adrian Wielgosik.

- Issue #28580: Optimize iterating split table values.
  Patch by Xiang Zhang.

- Issue #28583: PyDict_SetDefault didn't combine split table when needed.
  Patch by Xiang Zhang.

- Issue #28128: Deprecation warning for invalid str and byte escape
  sequences now prints better information about where the error
  occurs. Patch by Serhiy Storchaka and Eric Smith.

- Issue #28509: dict.update() no longer allocate unnecessary large memory.

- Issue #28426: Fixed potential crash in PyUnicode_AsDecodedObject() in debug
  build.

- Issue #28517: Fixed of-by-one error in the peephole optimizer that caused
  keeping unreachable code.

- Issue #28214: Improved exception reporting for problematic __set_name__
  attributes.

- Issue #23782: Fixed possible memory leak in _PyTraceback_Add() and exception
  loss in PyTraceBack_Here().

- Issue #28183: Optimize and cleanup dict iteration.

- Issue #26081: Added C implementation of asyncio.Future.
  Original patch by Yury Selivanov.

- Issue #28379: Added sanity checks and tests for PyUnicode_CopyCharacters().
  Patch by Xiang Zhang.

- Issue #28376: The type of long range iterator is now registered as Iterator.
  Patch by Oren Milman.

- Issue #28376: Creating instances of range_iterator by calling range_iterator
  type now is disallowed.  Calling iter() on range instance is the only way.
  Patch by Oren Milman.

- Issue #26906: Resolving special methods of uninitialized type now causes
  implicit initialization of the type instead of a fail.

- Issue #18287: PyType_Ready() now checks that tp_name is not NULL.
  Original patch by Niklas Koep.

- Issue #24098: Fixed possible crash when AST is changed in process of
  compiling it.

- Issue #28201: Dict reduces possibility of 2nd conflict in hash table when
  hashes have same lower bits.

- Issue #28350: String constants with null character no longer interned.

- Issue #26617: Fix crash when GC runs during weakref callbacks.

- Issue #27942: String constants now interned recursively in tuples and frozensets.

- Issue #28289: ImportError.__init__ now resets not specified attributes.

- Issue #21578: Fixed misleading error message when ImportError called with
  invalid keyword args.

- Issue #28203: Fix incorrect type in complex(1.0, {2:3}) error message.
  Patch by Soumya Sharma.

- Issue #28086: Single var-positional argument of tuple subtype was passed
  unscathed to the C-defined function.  Now it is converted to exact tuple.

- Issue #28214: Now __set_name__ is looked up on the class instead of the
  instance.

- Issue #27955: Fallback on reading /dev/urandom device when the getrandom()
  syscall fails with EPERM, for example when blocked by SECCOMP.

- Issue #28192: Don't import readline in isolated mode.

- Issue #27441: Remove some redundant assignments to ob_size in longobject.c.
  Thanks Oren Milman.

- Issue #27222: Clean up redundant code in long_rshift function. Thanks
  Oren Milman.

- Upgrade internal unicode databases to Unicode version 9.0.0.

- Issue #28131: Fix a regression in zipimport's compile_source().  zipimport
  should use the same optimization level as the interpreter.

- Issue #28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properly
  optimize memcpy().

- Issue #28120: Fix dict.pop() for splitted dictionary when trying to remove a
  "pending key" (Not yet inserted in split-table). Patch by Xiang Zhang.

- Issue #26182: Raise DeprecationWarning when async and await keywords are
  used as variable/attribute/class/function name.

- Issue #26182: Fix a refleak in code that raises DeprecationWarning.

- Issue #28721: Fix asynchronous generators aclose() and athrow() to
  handle StopAsyncIteration propagation properly.

- Issue #26110: Speed-up method calls: add LOAD_METHOD and CALL_METHOD
  opcodes.


Library
-------

- Issue #29169: Update zlib to 1.2.11.

- bpo-29800: Fix crashes in partial.__repr__ if the keys of partial.keywords
  are not strings.  Patch by Michael Seifert.

- bpo-8256: Fixed possible failing or crashing input() if attributes "encoding"
  or "errors" of sys.stdin or sys.stdout are not set or are not strings.

- bpo-28692: Using non-integer value for selecting a plural form in gettext is
  now deprecated.

- bpo-26121: Use C library implementation for math functions erf() and erfc().

- bpo-29619: os.stat() and os.DirEntry.inode() now convert inode (st_ino) using
  unsigned integers.

- bpo-28298: Fix a bug that prevented array 'Q', 'L' and 'I' from accepting big
  intables (objects that have __int__) as elements.

- bpo-29645: Speed up importing the webbrowser module.  webbrowser.register()
  is now thread-safe.

- bpo-28231: The zipfile module now accepts path-like objects for external
  paths.

- bpo-26915: index() and count() methods of collections.abc.Sequence now
  check identity before checking equality when do comparisons.

- bpo-28682: Added support for bytes paths in os.fwalk().

- bpo-29623: Allow use of path-like object as a single argument in
  ConfigParser.read().  Patch by David Ellis.

- bpo-9303: Migrate sqlite3 module to _v2 API.  Patch by Aviv Palivoda.

- bpo-28963: Fix out of bound iteration in asyncio.Future.remove_done_callback
  implemented in C.

- bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer closes before
  all pipes are closed.

- bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C
  to accept None argument as their pure Python implementation.

- bpo-29703: Fix asyncio to support instantiation of new event loops
  in child processes.

- bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any other
  exception) to exception(s) raised in the dispatched methods.
  Patch by Petr Motejlek.

- bpo-7769: Method register_function() of xmlrpc.server.SimpleXMLRPCDispatcher
  and its subclasses can now be used as a decorator.

- bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

- bpo-28624: Add a test that checks that cwd parameter of Popen() accepts
  PathLike objects.  Patch by Sayan Chowdhury.

- bpo-28518: Start a transaction implicitly before a DML statement.
  Patch by Aviv Palivoda.

- bpo-29742: get_extra_info() raises exception if get called on closed ssl transport.
  Patch by Nikolay Kim.

- Issue #16285: urrlib.parse.quote is now based on RFC 3986 and hence includes
  '~' in the set of characters that is not quoted by default. Patch by
  Christian Theune and Ratnadeep Debnath.

- bpo-29532: Altering a kwarg dictionary passed to functools.partial()
  no longer affects a partial object after creation.

- bpo-29110: Fix file object leak in aifc.open() when file is given as a
  filesystem path and is not in valid AIFF format. Patch by Anthony Zhang.

- bpo-22807: Add uuid.SafeUUID and uuid.UUID.is_safe to relay information from
  the platform about whether generated UUIDs are generated with a
  multiprocessing safe method.

- bpo-29576: Improve some deprecations in importlib. Some deprecated methods
  now emit DeprecationWarnings and have better descriptive messages.

- bpo-29534: Fixed different behaviour of Decimal.from_float()
  for _decimal and _pydecimal. Thanks Andrew Nester.

- Issue #28556: Various updates to typing module: typing.Counter, typing.ChainMap,
  improved ABC caching, etc. Original PRs by Jelle Zijlstra, Ivan Levkivskyi,
  Manuel Krebber, and Łukasz Langa.

- Issue #29100: Fix datetime.fromtimestamp() regression introduced in Python
  3.6.0: check minimum and maximum years.

- Issue #29416: Prevent infinite loop in pathlib.Path.mkdir

- Issue #29444: Fixed out-of-bounds buffer access in the group() method of
  the match object.  Based on patch by WGH.

- Issue #29377: Add SlotWrapperType, MethodWrapperType, and
  MethodDescriptorType built-in types to types module.
  Original patch by Manuel Krebber.

- Issue #29218: Unused install_misc command is now removed.  It has been
  documented as unused since 2000.  Patch by Eric N. Vander Weele.

- Issue #29368: The extend() method is now called instead of the append()
  method when unpickle collections.deque and other list-like objects.
  This can speed up unpickling to 2 times.

- Issue #29338: The help of a builtin or extension class now includes the
  constructor signature if __text_signature__ is provided for the class.

- Issue #29335: Fix subprocess.Popen.wait() when the child process has
  exited to a stopped instead of terminated state (ex: when under ptrace).

- Issue #29290: Fix a regression in argparse that help messages would wrap at
  non-breaking spaces.

- Issue #28735: Fixed the comparison of mock.MagickMock with mock.ANY.

- Issue #29197: Removed deprecated function ntpath.splitunc().

- Issue #29210: Removed support of deprecated argument "exclude" in
  tarfile.TarFile.add().

- Issue #29219: Fixed infinite recursion in the repr of uninitialized
  ctypes.CDLL instances.

- Issue #29192: Removed deprecated features in the http.cookies module.

- Issue #29193: A format string argument for string.Formatter.format()
  is now positional-only.

- Issue #29195: Removed support of deprecated undocumented keyword arguments
  in methods of regular expression objects.

- Issue #28969: Fixed race condition in C implementation of functools.lru_cache.
  KeyError could be raised when cached function with full cache was
  simultaneously called from differen threads with the same uncached arguments.

- Issue #20804: The unittest.mock.sentinel attributes now preserve their
  identity when they are copied or pickled.

- Issue #29142: In urllib.request, suffixes in no_proxy environment variable with
  leading dots could match related hostnames again (e.g. .b.c matches a.b.c).
  Patch by Milan Oberkirch.

- Issue #28961: Fix unittest.mock._Call helper: don't ignore the name parameter
  anymore. Patch written by Jiajun Huang.

- Issue #15812: inspect.getframeinfo() now correctly shows the first line of
  a context.  Patch by Sam Breese.

- Issue #28985: Update authorizer constants in sqlite3 module.
  Patch by Dingyuan Wang.

- Issue #29094: Offsets in a ZIP file created with extern file object and modes
  "w" and "x" now are relative to the start of the file.

- Issue #29079: Prevent infinite loop in pathlib.resolve() on Windows

- Issue #13051: Fixed recursion errors in large or resized
  curses.textpad.Textbox.  Based on patch by Tycho Andersen.

- Issue #9770: curses.ascii predicates now work correctly with negative
  integers.

- Issue #28427: old keys should not remove new values from
  WeakValueDictionary when collecting from another thread.

- Issue 28923: Remove editor artifacts from Tix.py.

- Issue #28871: Fixed a crash when deallocate deep ElementTree.

- Issue #19542: Fix bugs in WeakValueDictionary.setdefault() and
  WeakValueDictionary.pop() when a GC collection happens in another
  thread.

- Issue #20191: Fixed a crash in resource.prlimit() when passing a sequence that
  doesn't own its elements as limits.

- Issue #16255: subprocess.Popen uses /system/bin/sh on Android as the shell,
  instead of /bin/sh.

- Issue #28779: multiprocessing.set_forkserver_preload() would crash the
  forkserver process if a preloaded module instantiated some
  multiprocessing objects such as locks.

- Issue #26937: The chown() method of the tarfile.TarFile class does not fail
  now when the grp module cannot be imported, as for example on Android
  platforms.

- Issue #28847: dbm.dumb now supports reading read-only files and no longer
  writes the index file when it is not changed.  A deprecation warning is now
  emitted if the index file is missed and recreated in the 'r' and 'w' modes
  (will be an error in future Python releases).

- Issue #27030: Unknown escapes consisting of ``'\'`` and an ASCII letter in
  re.sub() replacement templates regular expressions now are errors.

- Issue #28835: Fix a regression introduced in warnings.catch_warnings():
  call warnings.showwarning() if it was overriden inside the context manager.

- Issue #27172: To assist with upgrades from 2.7, the previously documented
  deprecation of ``inspect.getfullargspec()`` has been reversed. This decision
  may be revisited again after the Python 2.7 branch is no longer officially
  supported.

- Issue #28740: Add sys.getandroidapilevel(): return the build time API version
  of Android as an integer. Function only available on Android.

- Issue #26273: Add new :data:`socket.TCP_CONGESTION` (Linux 2.6.13) and
  :data:`socket.TCP_USER_TIMEOUT` (Linux 2.6.37) constants. Patch written by
  Omar Sandoval.

- Issue #28752: Restored the __reduce__() methods of datetime objects.

- Issue #28727: Regular expression patterns, _sre.SRE_Pattern objects created
  by re.compile(), become comparable (only x==y and x!=y operators). This
  change should fix the issue #18383: don't duplicate warning filters when the
  warnings module is reloaded (thing usually only done in unit tests).

- Issue #20572: Remove the subprocess.Popen.wait endtime parameter.  It was
  deprecated in 3.4 and undocumented prior to that.

- Issue #25659: In ctypes, prevent a crash calling the from_buffer() and
  from_buffer_copy() methods on abstract classes like Array.

- Issue #28548: In the "http.server" module, parse the protocol version if
  possible, to avoid using HTTP 0.9 in some error responses.

- Issue #19717: Makes Path.resolve() succeed on paths that do not exist.
  Patch by Vajrasky Kok

- Issue #28563: Fixed possible DoS and arbitrary code execution when handle
  plural form selections in the gettext module.  The expression parser now
  supports exact syntax supported by GNU gettext.

- Issue #28387: Fixed possible crash in _io.TextIOWrapper deallocator when
  the garbage collector is invoked in other thread.  Based on patch by
  Sebastian Cufre.

- Issue #27517: LZMA compressor and decompressor no longer raise exceptions if
  given empty data twice.  Patch by Benjamin Fogle.

- Issue #28549: Fixed segfault in curses's addch() with ncurses6.

- Issue #28449: tarfile.open() with mode "r" or "r:" now tries to open a tar
  file with compression before trying to open it without compression.  Otherwise
  it had 50% chance failed with ignore_zeros=True.

- Issue #23262: The webbrowser module now supports Firefox 36+ and derived
  browsers.  Based on patch by Oleg Broytman.

- Issue #24241: The webbrowser in an X environment now prefers using the
  default browser directly. Also, the webbrowser register() function now has
  a documented 'preferred' argument, to specify browsers to be returned by
  get() with no arguments. Patch by David Steele

- Issue #27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale caused
  by representing the scale as float value internally in Tk.  tkinter.IntVar
  now works if float value is set to underlying Tk variable.

- Issue #28255: calendar.TextCalendar.prweek() no longer prints a space after
  a weeks's calendar.  calendar.TextCalendar.pryear() no longer prints redundant
  newline after a year's calendar.  Based on patch by Xiang Zhang.

- Issue #28255: calendar.TextCalendar.prmonth() no longer prints a space
  at the start of new line after printing a month's calendar.  Patch by
  Xiang Zhang.

- Issue #20491: The textwrap.TextWrapper class now honors non-breaking spaces.
  Based on patch by Kaarle Ritvanen.

- Issue #28353: os.fwalk() no longer fails on broken links.

- Issue #28430: Fix iterator of C implemented asyncio.Future doesn't accept
  non-None value is passed to it.send(val).

- Issue #27025: Generated names for Tkinter widgets now start by the "!" prefix
  for readability (was "`").

- Issue #25464: Fixed HList.header_exists() in tkinter.tix module by addin
  a workaround to Tix library bug.

- Issue #28488: shutil.make_archive() no longer adds entry "./" to ZIP archive.

- Issue #25953: re.sub() now raises an error for invalid numerical group
  reference in replacement template even if the pattern is not found in
  the string.  Error message for invalid group reference now includes the
  group index and the position of the reference.
  Based on patch by SilentGhost.

- Issue #28469: timeit now uses the sequence 1, 2, 5, 10, 20, 50,... instead
  of 1, 10, 100,... for autoranging.

- Issue #28115: Command-line interface of the zipfile module now uses argparse.
  Added support of long options.

- Issue #18219: Optimize csv.DictWriter for large number of columns.
  Patch by Mariatta Wijaya.

- Issue #28448: Fix C implemented asyncio.Future didn't work on Windows.

- Issue #23214: In the "io" module, the argument to BufferedReader and
  BytesIO's read1() methods is now optional and can be -1, matching the
  BufferedIOBase specification.

- Issue #28480: Fix error building socket module when multithreading is
  disabled.

- Issue #28240: timeit: remove ``-c/--clock`` and ``-t/--time`` command line
  options which were deprecated since Python 3.3.

- Issue #28240: timeit now repeats the benchmarks 5 times instead of only 3
  to make benchmarks more reliable.

- Issue #28240: timeit autorange now uses a single loop iteration if the
  benchmark takes less than 10 seconds, instead of 10 iterations.
  "python3 -m timeit -s 'import time' 'time.sleep(1)'" now takes 4 seconds
  instead of 40 seconds.

- Distutils.sdist now looks for README and setup.py files with case
  sensitivity. This behavior matches that found in Setuptools 6.0 and
  later. See `setuptools 100
  <https://github.com/pypa/setuptools/issues/100>`_ for rationale.

- Issue #24452: Make webbrowser support Chrome on Mac OS X. Patch by
  Ned Batchelder.

- Issue #20766: Fix references leaked by pdb in the handling of SIGINT
  handlers.

- Issue #27998: Fixed bytes path support in os.scandir() on Windows.
  Patch by Eryk Sun.

- Issue #28317: The disassembler now decodes FORMAT_VALUE argument.

- Issue #26293: Fixed writing ZIP files that starts not from the start of the
  file.  Offsets in ZIP file now are relative to the start of the archive in
  conforming to the specification.

- Issue #28380: unittest.mock Mock autospec functions now properly support
  assert_called, assert_not_called, and assert_called_once.

- Issue #28229: lzma module now supports pathlib.

- Issue #28321: Fixed writing non-BMP characters with binary format in plistlib.

- Issue #28225: bz2 module now supports pathlib.  Initial patch by Ethan Furman.

- Issue #28227: gzip now supports pathlib.  Patch by Ethan Furman.

- Issue #28332: Deprecated silent truncations in socket.htons and socket.ntohs.
  Original patch by Oren Milman.

- Issue #27358: Optimized merging var-keyword arguments and improved error
  message when passing a non-mapping as a var-keyword argument.

- Issue #28257: Improved error message when passing a non-iterable as
  a var-positional argument.  Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

- Issue #28322: Fixed possible crashes when unpickle itertools objects from
  incorrect pickle data.  Based on patch by John Leitch.

- Issue #28228: imghdr now supports pathlib.

- Issue #28226: compileall now supports pathlib.

- Issue #28314: Fix function declaration (C flags) for the getiterator() method
  of xml.etree.ElementTree.Element.

- Issue #28148: Stop using localtime() and gmtime() in the time
  module.
  
  Introduced platform independent _PyTime_localtime API that is
  similar to POSIX localtime_r, but available on all platforms.  Patch
  by Ed Schouten.

- Issue #28253: Fixed calendar functions for extreme months: 0001-01
  and 9999-12.
  
  Methods itermonthdays() and itermonthdays2() are reimplemented so
  that they don't call itermonthdates() which can cause datetime.date
  under/overflow.

- Issue #28275: Fixed possible use after free in the decompress()
  methods of the LZMADecompressor and BZ2Decompressor classes.
  Original patch by John Leitch.

- Issue #27897: Fixed possible crash in sqlite3.Connection.create_collation()
  if pass invalid string-like object as a name.  Patch by Xiang Zhang.

- Issue #18844: random.choices() now has k as a keyword-only argument
  to improve the readability of common cases and come into line
  with the signature used in other languages.

- Issue #18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py.
  Patch by Madison May.

- Issue #27611: Fixed support of default root window in the tkinter.tix module.
  Added the master parameter in the DisplayStyle constructor.

- Issue #27348: In the traceback module, restore the formatting of exception
  messages like "Exception: None".  This fixes a regression introduced in
  3.5a2.

- Issue #25651: Allow falsy values to be used for msg parameter of subTest().

- Issue #27778: Fix a memory leak in os.getrandom() when the getrandom() is
  interrupted by a signal and a signal handler raises a Python exception.

- Issue #28200: Fix memory leak on Windows in the os module (fix
  path_converter() function).

- Issue #25400: RobotFileParser now correctly returns default values for
  crawl_delay and request_rate.  Initial patch by Peter Wirtz.

- Issue #27932: Prevent memory leak in win32_ver().

- Fix UnboundLocalError in socket._sendfile_use_sendfile.

- Issue #28075: Check for ERROR_ACCESS_DENIED in Windows implementation of
  os.stat().  Patch by Eryk Sun.

- Issue #22493: Warning message emitted by using inline flags in the middle of
  regular expression now contains a (truncated) regex pattern.
  Patch by Tim Graham.

- Issue #25270: Prevent codecs.escape_encode() from raising SystemError when
  an empty bytestring is passed.

- Issue #28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

- Issue #25895: Enable WebSocket URL schemes in urllib.parse.urljoin.
  Patch by Gergely Imreh and Markus Holtermann.

- Issue #28114: Fix a crash in parse_envlist() when env contains byte strings.
  Patch by Eryk Sun.

- Issue #27599: Fixed buffer overrun in binascii.b2a_qp() and binascii.a2b_qp().

- Issue #27906: Fix socket accept exhaustion during high TCP traffic.
  Patch by Kevin Conway.

- Issue #28174: Handle when SO_REUSEPORT isn't properly supported.
  Patch by Seth Michael Larson.

- Issue #26654: Inspect functools.partial in asyncio.Handle.__repr__.
  Patch by iceboy.

- Issue #26909: Fix slow pipes IO in asyncio.
  Patch by INADA Naoki.

- Issue #28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

- Issue #27759: Fix selectors incorrectly retain invalid file descriptors.
  Patch by Mark Williams.

- Issue #28325: Remove vestigial MacOS 9 macurl2path module and its tests.

- Issue #28368: Refuse monitoring processes if the child watcher has
  no loop attached.
  Patch by Vincent Michel.

- Issue #28369: Raise RuntimeError when transport's FD is used with
  add_reader, add_writer, etc.

- Issue #28370: Speedup asyncio.StreamReader.readexactly.
  Patch by Коренберг Марк.

- Issue #28371: Deprecate passing asyncio.Handles to run_in_executor.

- Issue #28372: Fix asyncio to support formatting of non-python coroutines.

- Issue #28399: Remove UNIX socket from FS before binding.
  Patch by Коренберг Марк.

- Issue #27972: Prohibit Tasks to await on themselves.

- Issue #24142: Reading a corrupt config file left configparser in an
  invalid state.  Original patch by Florian Höch.

- Issue #29581: ABCMeta.__new__ now accepts **kwargs, allowing abstract base
  classes to use keyword parameters in __init_subclass__. Patch by Nate Soares.


Documentation
-------------

- bpo-28929: Link the documentation to its source file on GitHub.

- bpo-25008: Document smtpd.py as effectively deprecated and add a pointer to
  aiosmtpd, a third-party asyncio-based replacement.

- Issue #26355: Add canonical header link on each page to corresponding major
  version of the documentation. Patch by Matthias Bussonnier.

- Issue #29349: Fix Python 2 syntax in code for building the documentation.

- Issue #23722: The data model reference and the porting section in the
  3.6 What's New guide now cover the additional ``__classcell__`` handling
  needed for custom metaclasses to fully support PEP 487 and zero-argument
  ``super()``.

- Issue #28513: Documented command-line interface of zipfile.


Tests
-----

- Issue #24932: Use proper command line parsing in _testembed

- Issue #28950: Disallow -j0 to be combined with -T/-l in regrtest
  command line arguments.

- Issue #28683: Fix the tests that bind() a unix socket and raise
  PermissionError on Android for a non-root user.

- Issue #26936: Fix the test_socket failures on Android - getservbyname(),
   getservbyport() and getaddrinfo() are broken on some Android API levels.

- Issue #28666: Now test.support.rmtree is able to remove unwritable or
  unreadable directories.

- Issue #23839: Various caches now are cleared before running every test file.

- Issue #26944: Fix test_posix for Android where 'id -G' is entirely wrong or
  missing the effective gid.

- Issue #28409: regrtest: fix the parser of command line arguments.

- Issue #28217: Adds _testconsole module to test console input.

- Issue #26939: Add the support.setswitchinterval() function to fix
  test_functools hanging on the Android armv7 qemu emulator.


Build
-----

- bpo-27593: sys.version and the platform module python_build(),
  python_branch(), and python_revision() functions now use
  git information rather than hg when building from a repo.

- bpo-29572: Update Windows build and OS X installers to use OpenSSL 1.0.2k.

- Issue #27659: Prohibit implicit C function declarations: use
  -Werror=implicit-function-declaration when possible (GCC and Clang, but it
  depends on the compiler version). Patch written by Chi Hsuan Yen.

- Issue #29384: Remove old Be OS helper scripts.

- Issue #26851: Set Android compilation and link flags.

- Issue #28768: Fix implicit declaration of function _setmode. Patch by
  Masayuki Yamamoto

- Issue #29080: Removes hard dependency on hg.exe from PCBuild/build.bat

- Issue #23903: Added missed names to PC/python3.def.

- Issue #28762: lockf() is available on Android API level 24, but the F_LOCK
  macro is not defined in android-ndk-r13.

- Issue #28538: Fix the compilation error that occurs because if_nameindex() is
  available on Android API level 24, but the if_nameindex structure is not
  defined.

- Issue #20211: Do not add the directory for installing C header files and the
  directory for installing object code libraries to the cross compilation
  search paths. Original patch by Thomas Petazzoni.

- Issue #28849: Do not define sys.implementation._multiarch on Android.

- Issue #10656: Fix out-of-tree building on AIX.  Patch by Tristan Carel and
  Michael Haubenwallner.

- Issue #26359: Rename --with-optimiations to --enable-optimizations.

- Issue #28444: Fix missing extensions modules when cross compiling.

- Issue #28208: Update Windows build and OS X installers to use SQLite 3.14.2.

- Issue #28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.

- Issue #21124: Fix building the _struct module on Cygwin by passing ``NULL``
  instead of ``&PyType_Type`` to PyVarObject_HEAD_INIT.  Patch by Masayuki
  Yamamoto.

- Issue #13756: Fix building extensions modules on Cygwin.  Patch by Roumen
  Petrov, based on original patch by Jason Tishler.

- Issue #21085: Add configure check for siginfo_t.si_band, which Cygwin does
  not provide.  Patch by Masayuki Yamamoto with review and rebase by Erik Bray.

- Issue #28258: Fixed build with Estonian locale (python-config and distclean
  targets in Makefile).  Patch by Arfrever Frehtes Taifersar Arahesis.

- Issue #26661: setup.py now detects system libffi with multiarch wrapper.

- Issue #27979: A full copy of libffi is no longer bundled for use when
  building _ctypes on non-OSX UNIX platforms.  An installed copy of libffi is
  now required when building _ctypes on such platforms.

- Issue #15819: Remove redundant include search directory option for building
  outside the source tree.

- Issue #28676: Prevent missing 'getentropy' declaration warning on macOS.
  Patch by Gareth Rees.


Windows
-------

- bpo-29579: Removes readme.txt from the installer.

- Issue #25778: winreg does not truncate string correctly (Patch by Eryk Sun)

- Issue #28896: Deprecate WindowsRegistryFinder and disable it by default

- Issue #28522: Fixes mishandled buffer reallocation in getpathp.c

- Issue #28402: Adds signed catalog files for stdlib on Windows.

- Issue #28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch by
  Eryk Sun)

- Issue #28251: Improvements to help manuals on Windows.

- Issue #28110: launcher.msi has different product codes between 32-bit and
  64-bit

- Issue #28161: Opening CON for write access fails

- Issue #28162: WindowsConsoleIO readall() fails if first line starts with
  Ctrl+Z

- Issue #28163: WindowsConsoleIO fileno() passes wrong flags to
  _open_osfhandle

- Issue #28164: _PyIO_get_console_type fails for various paths

- Issue #28137: Renames Windows path file to ._pth

- Issue #28138: Windows ._pth file should allow import site


Tools/Demos
-----------

- bpo-24037: Argument Clinic now uses the converter `bool(accept={int})` rather
  than `int` for semantical booleans.  This avoids repeating the default
  value for Python and C and will help in converting to `bool` in future.

- Issue #29367: python-gdb.py now supports also ``method-wrapper``
  (``wrapperobject``) objects.

- Issue #28023: Fix python-gdb.py didn't support new dict implementation.

- Issue #15369: The pybench and pystone microbenchmark have been removed from
  Tools. Please use the new Python benchmark suite
  https://github.com/python/performance which is more reliable and includes a
  portable version of pybench working on Python 2 and Python 3.

- Issue #28102: The zipfile module CLI now prints usage to stderr.
  Patch by Stephen J. Turnbull.


C API
-----

- Issue #27867: Function PySlice_GetIndicesEx() is deprecated and replaced with
  a macro if Py_LIMITED_API is not set or set to the value between 0x03050400
  and 0x03060000 (not including) or 0x03060100 or higher.  Added functions
  PySlice_Unpack() and PySlice_AdjustIndices().

- Issue #29083: Fixed the declaration of some public API functions.
  PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not available in
  limited API.  PyArg_ValidateKeywordArguments(), PyArg_UnpackTuple() and
  Py_BuildValue() were not available in limited API of version < 3.3 when
  PY_SSIZE_T_CLEAN is defined.

- Issue #28769: The result of PyUnicode_AsUTF8AndSize() and PyUnicode_AsUTF8()
  is now of type ``const char *`` rather of ``char *``.

- Issue #29058: All stable API extensions added after Python 3.2 are now
  available only when Py_LIMITED_API is set to the PY_VERSION_HEX value of
  the minimum Python version supporting this API.

- Issue #28822: The index parameters *start* and *end* of PyUnicode_FindChar()
  are now adjusted to behave like ``str[start:end]``.

- Issue #28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.

- Issue #28761: The fields name and doc of structures PyMemberDef, PyGetSetDef,
  PyStructSequence_Field, PyStructSequence_Desc, and wrapperbase are now of
  type ``const char *`` rather of ``char *``.

- Issue #28748: Private variable _Py_PackageContext is now of type ``const char *``
  rather of ``char *``.

- Issue #19569: Compiler warnings are now emitted if use most of deprecated
  functions.

- Issue #28426: Deprecated undocumented functions PyUnicode_AsEncodedObject(),
  PyUnicode_AsDecodedObject(), PyUnicode_AsDecodedUnicode() and
  PyUnicode_AsEncodedUnicode().



What's New in Python 3.6.1 release candidate 1?
===============================================

Release date: XXXX-XX-XX

Core and Builtins
-----------------

- Issue #28932: Do not include <sys/random.h> if it does not exist.

- Issue #25677: Correct the positioning of the syntax error caret for
  indented blocks.  Based on patch by Michael Layzell.

- Issue #29000: Fixed bytes formatting of octals with zero padding in alternate
  form.

- Issue #26919: On Android, operating system data is now always encoded/decoded
  to/from UTF-8, instead of the locale encoding to avoid inconsistencies with
  os.fsencode() and os.fsdecode() which are already using UTF-8.

- Issue #28991:  functools.lru_cache() was susceptible to an obscure reentrancy
  bug triggerable by a monkey-patched len() function.

- Issue #28739: f-string expressions are no longer accepted as docstrings and
  by ast.literal_eval() even if they do not include expressions.

- Issue #28512: Fixed setting the offset attribute of SyntaxError by
  PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

- Issue #28918: Fix the cross compilation of xxlimited when Python has been
  built with Py_DEBUG defined.

- Issue #28731: Optimize _PyDict_NewPresized() to create correct size dict.
  Improve speed of dict literal with constant keys up to 30%.


Library
-------

- Issue #29085: Allow random.Random.seed() to use high quality OS randomness
  rather than the pid and time.

- Issue 28923: Remove editor artifacts from Tix.py.

- Issue #29055:  Neaten-up empty population error on random.choice()
  by suppressing the upstream exception.

- Issue #28871: Fixed a crash when deallocate deep ElementTree.

- Issue #19542: Fix bugs in WeakValueDictionary.setdefault() and
  WeakValueDictionary.pop() when a GC collection happens in another
  thread.

- Issue #20191: Fixed a crash in resource.prlimit() when passing a sequence that
  doesn't own its elements as limits.

- Issue #28779: multiprocessing.set_forkserver_preload() would crash the
  forkserver process if a preloaded module instantiated some
  multiprocessing objects such as locks.

- Issue #28847: dbm.dumb now supports reading read-only files and no longer
  writes the index file when it is not changed.

- Issue #26937: The chown() method of the tarfile.TarFile class does not fail
  now when the grp module cannot be imported, as for example on Android
  platforms.


Documentation
-------------

- Issue #29349: Fix Python 2 syntax in code for building the documentation.


Tests
-----

- Issue #28950: Disallow -j0 to be combined with -T/-l in regrtest
  command line arguments.

- Issue #28683: Fix the tests that bind() a unix socket and raise
  PermissionError on Android for a non-root user.

- Issue #26939: Add the support.setswitchinterval() function to fix
  test_functools hanging on the Android armv7 qemu emulator.


Build
-----

- Issue #28762: lockf() is available on Android API level 24, but the F_LOCK
  macro is not defined in android-ndk-r13.

- Issue #28538: Fix the compilation error that occurs because if_nameindex() is
  available on Android API level 24, but the if_nameindex structure is not
  defined.

- Issue #20211: Do not add the directory for installing C header files and the
  directory for installing object code libraries to the cross compilation
  search paths. Original patch by Thomas Petazzoni.

- Issue #28849: Do not define sys.implementation._multiarch on Android.


Windows
-------

- Issue #29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)

- Issue #28164: Correctly handle special console filenames (patch by Eryk Sun)

- Issue #29409: Implement PEP 529 for io.FileIO (Patch by Eryk Sun)

- Issue #29392: Prevent crash when passing invalid arguments into msvcrt module.

- Issue #25778: winreg does not truncate string correctly (Patch by Eryk Sun)

- Issue #28896: Deprecate WindowsRegistryFinder and disable it by default.



What's New in Python 3.6.0 final?
=================================

Release date: 2016-12-23

No changes since release candidate 2




What's New in Python 3.6.0 release candidate 2?
===============================================

Release date: 2016-12-16

Core and Builtins
-----------------

- Issue #28147: Fix a memory leak in split-table dictionaries: setattr()
  must not convert combined table into split table. Patch written by INADA
  Naoki.

- Issue #28990: Fix asyncio SSL hanging if connection is closed before
  handshake is completed. (Patch by HoHo-Ho)


Build
-----

- Issue #28898: Prevent gdb build errors due to HAVE_LONG_LONG redefinition.


Windows
-------

- Issue #28896: Deprecate WindowsRegistryFinder.


Tools/Demos
-----------

- Issue #28770: Fix python-gdb.py for fastcalls.



What's New in Python 3.6.0 release candidate 1?
===============================================

Release date: 2016-12-06

Core and Builtins
-----------------

- Issue #23722: Rather than silently producing a class that doesn't support
  zero-argument ``super()`` in methods, failing to pass the new
  ``__classcell__`` namespace entry up to ``type.__new__`` now results in a
  ``DeprecationWarning`` and a class that supports zero-argument ``super()``.

- Issue #28797: Modifying the class __dict__ inside the __set_name__ method of
  a descriptor that is used inside that class no longer prevents calling the
  __set_name__ method of other descriptors.

- Issue #28782: Fix a bug in the implementation ``yield from`` when checking
  if the next instruction is YIELD_FROM. Regression introduced by WORDCODE
  (issue #26647).


Library
-------

- Issue #27030: Unknown escapes in re.sub() replacement template are allowed
  again.  But they still are deprecated and will be disabled in 3.7.

- Issue #28835: Fix a regression introduced in warnings.catch_warnings():
  call warnings.showwarning() if it was overriden inside the context manager.

- Issue #27172: To assist with upgrades from 2.7, the previously documented
  deprecation of ``inspect.getfullargspec()`` has been reversed. This decision
  may be revisited again after the Python 2.7 branch is no longer officially
  supported.

- Issue #26273: Add new :data:`socket.TCP_CONGESTION` (Linux 2.6.13) and
  :data:`socket.TCP_USER_TIMEOUT` (Linux 2.6.37) constants. Patch written by
  Omar Sandoval.

- Issue #24142: Reading a corrupt config file left configparser in an
  invalid state.  Original patch by Florian Höch.

- Issue #28843: Fix asyncio C Task to handle exceptions __traceback__.


Documentation
-------------

- Issue #23722: The data model reference and the porting section in the What's
  New guide now cover the additional ``__classcell__`` handling needed for
  custom metaclasses to fully support PEP 487 and zero-argument ``super()``.


Tools/Demos
-----------

- Issue #28023: Fix python-gdb.py didn't support new dict implementation.


C API
-----

- Issue #28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.