3.6.2rc1.rst

Update expat copy from 2.1.1 to 2.2.0 to get fixes of :cve:`2016-0718` and :cve:`2016-4472`. See https://sourceforge.net/p/expat/bugs/537/ for more information.

Removed a too-strict assertion that failed for certain f-strings, such as eval("f'\n'") and eval("f'\r'").

Move co_extra_freefuncs to not be per-thread to avoid crashes

Fixed parsing backslashes in f-strings.

Fixed various segfaults with dict when input collections are mutated during searching, inserting or comparing. Based on patches by Duane Griffin and Tim Mitchell.

Fixed type.__setattr__() and type.__delattr__() for non-interned attribute names. Based on patch by Eryk Sun.

If a KeyboardInterrupt happens when the interpreter is in the middle of resuming a chain of nested 'yield from' or 'await' calls, it's now correctly delivered to the innermost frame.

sys.getsizeof() on a code object now returns the sizes which includes the code struct and sizes of objects which it references. Patch by Donghee Na.

Fix memory usage regression of set and frozenset object.

Fixed error messages in the index() method of tuple, list and deque when pass indices of wrong type.

Show correct error messages when any of the pthread_* calls in thread_pthread.h fails.

bool(range) works even if len(range) raises :exc:`OverflowError`.

Fix wrapping coroutine return values in StopIteration.

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

Fix a regression that bytes format may fail when containing zero bytes inside.

If max_line_length=None is specified while using the Compat32 policy, it is no longer ignored. Patch by Mircea Cosbuc.

Functional API of enum allows to create empty enums. Patched by Donghee Na

Fix race condition between signal delivery and wakeup file descriptor. Patch by Nathaniel Smith.

lib2to3 now recognizes rb'...' and f'...' strings.

unittest.TestCase.assertRaises() now manually breaks a reference cycle to not keep objects alive longer than expected.

inspect.signature() now supports callables with variable-argument parameters wrapped with partialmethod. Patch by Donghee Na.

Fix path calculation in imp.load_package(), fixing it for cases when a package is only shipped with bytecodes. Patch by Alexandru Ardelean.

Fixed comparison check for ipaddress.ip_interface objects. Patch by Sanjay Sundaresan.

re.compile() no longer raises a BytesWarning when compiling a bytes instance with misplaced inline modifier. Patch by Roy Williams.

Avoid race condition in multiprocessing cleanup (#2159)

The traceback no longer displayed for SystemExit raised in a callback registered by atexit.

Don't log exceptions if Task/Future "cancel()" method was called.

Updates to typing module: Add generic AsyncContextManager, add support for ContextManager on all versions. Original PRs by Jelle Zijlstra and Ivan Levkivskyi

Fix ssl sockets leaks when connection is aborted in asyncio/ssl implementation. Patch by Michaël Sghaïer.

Closing transport during handshake process leaks open socket. Patch by Nikolay Kim

Fix waiter cancellation in asyncio.Lock. Patch by Mathieu Sornay.

On Windows, subprocess.Popen.communicate() now also ignore EINVAL on stdin.write() if the child process is still running but closed the pipe.

inspect.isabstract() now works during __init_subclass__. Patch by Nate Soares.

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

faulthandler now correctly filters and displays exception codes on Windows

Fix the problem that logging.handlers.SysLogHandler cannot handle IPv6 addresses.

Preserve generator state when _random.Random.setstate() raises an exception. Patch by Bryan Olson.

multiprocessing.Queue._feed background running thread do not break from main loop on exception.

Fix handling escape characters in HZ codec. Based on patch by Ma Lin.

Fix AttributeError when using SimpleQueue.empty() under spawn and forkserver start methods.

imaplib and poplib now catch the Windows socket WSAEINVAL error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted. This error occurs sometimes on SSL connections.

Warnings emitted when compile a regular expression now always point to the line in the user code. Previously they could point into inners of the re module if emitted from inside of groups or conditionals.

Fixed Task.cancel() can be ignored when the task is running coroutine and the coroutine returned without any more await.

contextlib.AbstractContextManager now supports anti-registration by setting __enter__ = None or __exit__ = None, following the pattern introduced in bpo-25958. Patch by Jelle Zijlstra.

Weaken the condition of deprecation warnings for inline modifiers. Now allowed several subsequential inline modifiers at the start of the pattern (e.g. '(?i)(?s)...'). In verbose mode whitespaces and comments now are allowed before and between inline modifiers (e.g. '(?x) (?i) (?s)...').

Fix range checking in GB18030 decoder. Original patch by Ma Lin.

Change resulted because of zipfile breakage. (See also: bpo-29094)

Removed the __init__ methods of _json's scanner and encoder. Misusing them could cause memory leaks or crashes. Now scanner and encoder objects are completely initialized in the __new__ methods.

Avoid KeyboardInterrupt tracebacks in forkserver helper process when Ctrl-C is received.

Various updates to typing module: add typing.NoReturn type, use WrapperDescriptorType, minor bug-fixes. Original PRs by Jim Fasarakis-Hilliard and Ivan Levkivskyi.

Fix getsockname() for unbound AF_UNIX sockets on Linux.

Fixed leaks and crashes in errors handling in the parser module.

Fixed crashes in IOBase methods __next__() and readlines() when readline() or __next__() respectively return non-sizeable object. Fixed possible other errors caused by not checking results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

Allowed calling the close() method of the zip entry writer object multiple times. Writing to a closed writer now always produces a ValueError.

_io._IOBase.readlines will check if it's closed first when hint is present.

Fixed race condition in pathlib mkdir with flags parents=True. Patch by Armin Rigo.

Fixed arbitrary unchaining of RuntimeError exceptions in contextlib.contextmanager. Patch by Siddharth Velankar.

Pickling and copying ImportError now preserves name and path attributes.

Fixed memory leaks in the replace() method of datetime and time objects when pass out of bound fold argument.

Fix a crash in itertools.chain.from_iterable when encountering long runs of empty iterables.

Fixed multiple crashes in ElementTree caused by race conditions and wrong types.

Fixed a bug in pools in multiprocessing.pool that raising an exception at the very first of an iterable may swallow the exception or make the program hang. Patch by Davin Potts and Xiang Zhang.

Avoid incorrect errors raised by Path.mkdir(exist_ok=True) when the OS gives priority to errors such as EACCES over EEXIST.

Release references to tasks, their arguments and their results as soon as they are finished in multiprocessing.Pool.

faulthandler: Restore the old sigaltstack during teardown. Patch by Christophe Zeitouny.

Fixed crashes in repr of recursive buffered file-like objects.

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

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

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

Fix a bug that prevented array 'Q', 'L' and 'I' from accepting big intables (objects that have __int__) as elements. Patch by Oren Milman.

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

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

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

path.resolve(strict=False) no longer cuts the path after the first element not present in the filesystem. Patch by Antoine Pietri.

Fix several problems with IDLE's autocompletion box. The following should now work: clicking on selection box items; using the scrollbar; selecting an item by hitting Return. Hangs on MacOSX should no longer happen. Patch by Louie Lu.

Add doc subsubsection about IDLE failure to start. Popup no-connection message directs users to this section.

Fix reference leaks in IDLE tests. Patches by Louie Lu and Terry Jan Reedy.

Add docstrings for textview.py and use PEP8 names. Patches by Cheryl Sabella and Terry Jan Reedy.

Help-about: use pep8 names and add tests. Increase coverage to 100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan Reedy.

Add _utest option to textview; add new tests. Increase coverage to 100%. Patches by Louie Lu and Terry Jan Reedy.

Function PySlice_GetIndicesEx() no longer replaced with a macro if Py_LIMITED_API is not set.

Add --with-assertions configure flag to explicitly enable C assert() checks. Defaults to off. --with-pydebug implies --with-assertions.

Fix out-of-tree builds of Python when configured with --with--dtrace.

Prevent unnecessary rebuilding of Python during make test, make install and some other make targets when configured with --enable-optimizations.

Don't regenerate generated files based on file modification time anymore: the action is now explicit. Replace make touch with make regen-all.

Fix --enable-optimization didn't work.

Add missing attribute related constants in curses documentation.

the link targets for :func:`bytes` and :func:`bytearray` are now their respective type definitions, rather than the corresponding builtin function entries. Use :ref:`bytes <func-bytes>` and :ref:`bytearray <func-bytearray>` to reference the latter. In order to ensure this and future cross-reference updates are applied automatically, the daily documentation builds now disable the default output caching features in Sphinx.

Add missing info of code object in inspect documentation.

python-gdb.py now supports also method-wrapper (wrapperobject) objects.

test_thread: setUp() now uses support.threading_setup() and support.threading_cleanup() to wait until threads complete to avoid random side effects on following tests. Initial patch written by Grzegorz Grzywacz.

Enhanced functions swap_attr() and swap_item() in the test.support module. They now work when delete replaced attribute or item inside the with statement. The old value of the attribute or item (or None if it doesn't exist) now will be assigned to the target of the "as" clause, if there is one.

Locate msbuild.exe on Windows when building rather than vcvarsall.bat

The build process on Windows no longer depends on Subversion, instead pulling external code from GitHub via a Python script. If Python 3.6 is not found on the system (via py -3.6), NuGet is used to download a copy of 32-bit Python.