3.9.0a1.rst

:mod:`runpy` now uses :meth:`io.open_code` to open code files. Patch by Jason Killen.

Add additional audit events for the :mod:`ctypes` module.

Fixes audit event for :func:`os.system` to be named os.system.

Escape the server title of :class:`xmlrpc.server.DocXMLRPCServer` when rendering the document page as HTML. (Contributed by Donghee Na in :issue:`38243`.)

Update vendorized expat library version to 2.2.8, which resolves :cve:`2019-15903`.

Fixes email._header_value_parser.get_unstructured going into an infinite loop for a specific case in which the email header does not have trailing whitespace, and the case in which it contains an invalid encoded word. Patch by Ashwin Ramaswami.

Fix an infinite loop when parsing specially crafted email headers. Patch by Abhilash Raj.

Adds audit events for the range of supported run commands (see :ref:`using-on-general`).

ssl.match_hostname() no longer accepts IPv4 addresses with additional text after the address and only quad-dotted notation without trailing whitespaces. Some inet_aton() implementations ignore whitespace and all data after whitespace, e.g. '127.0.0.1 whatever'.

Adds audit events for :mod:`ensurepip`, :mod:`ftplib`, :mod:`glob`, :mod:`imaplib`, :mod:`!nntplib`, :mod:`pdb`, :mod:`poplib`, :mod:`shutil`, :mod:`smtplib`, :mod:`sqlite3`, :mod:`subprocess`, :mod:`!telnetlib`, :mod:`tempfile` and :mod:`webbrowser`, as well as :func:`os.listdir`, :func:`os.scandir` and :func:`breakpoint`.

:func:`io.open_code` is now used when reading :file:`.pth` files.

Updated OpenSSL to 1.1.1c in Windows installer

Fix parsing of invalid email addresses with more than one @ (e.g. a@b@c.com.) to not return the part before 2nd @ as valid email address. Patch by maxking & jpic.

Replace Py_FatalError() call with a regular :exc:`RuntimeError` exception in :meth:`float.__getformat__`.

Optimized :func:`math.floor()`, :func:`math.ceil()` and :func:`math.trunc()` for floats.

Fixed a bug in the compiler that was causing to raise in the presence of break statements and continue statements inside always false while loops. Patch by Pablo Galindo.

Optimized some set operations (e.g. |, ^, and -) of dict_keys. d.keys() | other was slower than set(d) | other but they are almost same performance for now.

"".replace("", s, n) now returns s instead of an empty string for all non-zero n. There are similar changes for :class:`bytes` and :class:`bytearray` objects.

Fixed line numbers and column offsets for AST nodes for calls without arguments in decorators.

Fix a segmentation fault when using reverse iterators of empty dict objects. Patch by Donghee Na and Inada Naoki.

:class:`bytearray`, :class:`~array.array` and :class:`~mmap.mmap` objects allow now to export more than 2**31 buffers at a time.

Fixed a bug where the scope of named expressions was not being resolved correctly in the presence of the global keyword. Patch by Pablo Galindo.

Activate the GC_DEBUG macro for debug builds of the interpreter (when Py_DEBUG is set). Patch by Pablo Galindo.

When the garbage collector makes a collection in which some objects resurrect (they are reachable from outside the isolated cycles after the finalizers have been executed), do not block the collection of all objects that are still unreachable. Patch by Pablo Galindo and Tim Peters.

When cyclic garbage collection (gc) runs finalizers that resurrect unreachable objects, the current gc run ends, without collecting any cyclic trash. However, the statistics reported by collect() and get_stats() claimed that all cyclic trash found was collected, and that the resurrected objects were collected. Changed the stats to report that none were collected.

In debug mode, :c:func:`PyObject_GC_Track` now calls tp_traverse() of the object type to ensure that the object is valid: test that objects visited by tp_traverse() are valid.

Remove unnecessary intersection and update set operation in dictview with empty set. (Contributed by Donghee Na in :issue:`38210`.)

Check the error from the system's underlying crypt or crypt_r.

On FreeBSD, Python no longer calls fedisableexcept() at startup to control the floating point control mode. The call became useless since FreeBSD 6: it became the default mode.

Fix a bug due to the interaction of weakrefs and the cyclic garbage collector. We must clear any weakrefs in garbage in order to prevent their callbacks from executing and causing a crash.

Fix warnings options priority: PyConfig.warnoptions has the highest priority, as stated in the PEP 587.

Predict BUILD_MAP_UNPACK_WITH_CALL -> CALL_FUNCTION_EX opcode pairs in the main interpreter loop. Patch by Brandt Bucher.

Improve error handling for the assert_has_calls and assert_has_awaits methods of mocks. Fixed a bug where any errors encountered while binding the expected calls to the mock's spec were silently swallowed, leading to misleading error output.

Better control over symbol visibility is provided through use of the visibility attributes available in gcc >= 4.0, provided in a uniform way across POSIX and Windows. The POSIX build files have been updated to compile with -fvisibility=hidden, minimising exported symbols.

Optimized the :class:`dict` constructor and the :meth:`~dict.update` method for the case when the argument is a dict.

Python now dumps path configuration if it fails to import the Python codecs of the filesystem and stdio encodings.

Allow to call async_generator_athrow().throw(...) even for non-started async generator helper. It fixes annoying warning at the end of :func:`asyncio.run` call.

Fix an off-by-one error in PyState_AddModule that could cause out-of-bounds memory access.

The select module is now PEP-384 compliant and no longer has static state

ast module updated to PEP-384 and all statics removed

The struct module is now PEP-384 compatible

The random module is now PEP-384 compatible

zlib module made PEP-384 compatible

Make pwd extension module PEP-384 compatible

grp module made PEP-384 compatible

Make _posixsubprocess PEP-384 compatible

Make termios extension module PEP-384 compatible

Fixed comparing and creating of InterpreterID and ChannelID.

Fix possible signed integer overflow when handling slices. Patch by hongweipeng.

Fixed silencing arbitrary errors if an attribute lookup fails in several sites. Only AttributeError should be silenced.

Optimize set difference_update for the case when the other set is much larger than the base set. (Suggested by Evgeny Kapun with code contributed by Michele Orrù).

The implementation of :func:`~unicodedata.is_normalized` has been greatly sped up on strings that aren't normalized, by implementing the full normalization-quick-check algorithm from the Unicode standard.

Adjust correctly the recursion level in the symtable generation for named expressions. Patch by Pablo Galindo.

The CHECK_SMALL_INT macro used inside :file:`Object/longobject.c` has been replaced with an explicit return at each call site.

Fix :func:`codecs.lookup` to normalize the encoding name the same way than :func:`encodings.normalize_encoding`, except that :func:`codecs.lookup` also converts the name to lower case.

Fixed compilation of :keyword:`break` and :keyword:`continue` in the :keyword:`finally` block when the corresponding :keyword:`try` block contains :keyword:`return` with a non-constant value.

Improve import error message for partially initialized module on circular from imports - by Anthony Sottile.

Fix handling of negative indices in :c:member:`~PySequenceMethods.sq_item` of :class:`bytearray`. Patch by Sergey Fedoseev.

Slightly improve performance of :c:func:`PyLong_FromUnsignedLong`, :c:func:`PyLong_FromUnsignedLongLong` and :c:func:`PyLong_FromSize_t`. Patch by Sergey Fedoseev.

Ensure explicit relative imports from interactive sessions and scripts (having no parent package) always raise ImportError, rather than treating the current module as the package. Patch by Ben Lewis.

Reverted :issue:`32912`: emitting :exc:`SyntaxWarning` instead of :exc:`DeprecationWarning` for invalid escape sequences in string and bytes literals.

PEP 572: As described in the PEP, assignment expressions now raise :exc:`SyntaxError` when their interaction with comprehension scoping results in an ambiguous target scope.

The TargetScopeError subclass originally proposed by the PEP has been removed in favour of just raising regular syntax errors for the disallowed cases.

Fix potential use of uninitialized memory in :func:`os.wait3`.

Decoding bytes objects larger than 2GiB is faster and no longer fails when a multibyte characters spans a chunk boundary.

The :keyword:`assert` statement now works properly if the :exc:`AssertionError` exception is being shadowed. Patch by Zackery Spytz.

Removed object cache (free_list) for bound method objects. Temporary bound method objects are less used than before thanks to the LOAD_METHOD opcode and the _PyObject_VectorcallMethod C API.

Fixed minor inconsistency in :meth:`list.__contains__`, :meth:`tuple.__contains__` and a few other places. The collection's item is now always at the left and the needle is on the right of ==.

Update differing exception between :meth:`builtins.__import__` and :meth:`importlib.__import__`.

When adding a wrapper descriptor from one class to a different class (for example, setting __add__ = str.__add__ on an int subclass), an exception is correctly raised when the operator is called.

Swap the positions of the posonlyargs and args parameters in the constructor of :class:`ast.parameters` nodes.

Optimized pymalloc for non PGO build.

Compute allocated pymalloc blocks inside _Py_GetAllocatedBlocks(). This slows down _Py_GetAllocatedBlocks() but gives a small speedup to _PyObject_Malloc() and _PyObject_Free().

Fix :func:`sys.excepthook` and :c:func:`PyErr_Display` if a filename is a bytes string. For example, for a SyntaxError exception where the filename attribute is a bytes string.

Fix SyntaxError indicator printing too many spaces for multi-line strings - by Anthony Sottile.

:meth:`bytearray.extend` now correctly handles errors that arise during iteration. Patch by Brandt Bucher.

The undocumented sys.callstats() function has been removed. Since Python 3.7, it was deprecated and always returned None. It required a special build option CALL_PROFILE which was already removed in Python 3.7.

Remove sys.getcheckinterval() and sys.setcheckinterval() functions. They were deprecated since Python 3.2. Use :func:`sys.getswitchinterval` and :func:`sys.setswitchinterval` instead. Remove also check_interval field of the PyInterpreterState structure.

In development mode and in debug build, encoding and errors arguments are now checked on string encoding and decoding operations. Examples: :func:`open`, :meth:`str.encode` and :meth:`bytes.decode`.

By default, for best performances, the errors argument is only checked at the first encoding/decoding error, and the encoding argument is sometimes ignored for empty strings.

Optimized decoding short ASCII string with UTF-8 and ascii codecs. b"foo".decode() is about 15% faster. Patch by Inada Naoki.

Improved support of the surrogatepass error handler in the UTF-8 and UTF-16 incremental decoders.

:func:`open`, :func:`io.open`, :func:`codecs.open` and :class:`fileinput.FileInput` no longer accept 'U' ("universal newline") in the file mode. This flag was deprecated since Python 3.3.

Reverse evaluation order of key: value in dict comprehensions as proposed in PEP 572. I.e. in {k: v for ...}, k will be evaluated before v.

Fix the :c:func:`PySys_Audit` call in :class:`mmap.mmap`.

Remove an unnecessary Py_XINCREF in classobject.c.

Fix a bug in the peephole optimizer that was not treating correctly constant conditions with binary operators. Patch by Pablo Galindo.

Python now gets the absolute path of the script filename specified on the command line (ex: "python3 script.py"): the __file__ attribute of the __main__ module and sys.path[0] become an absolute path, rather than a relative path.

Python's small object allocator (obmalloc.c) now allows (no more than) one empty arena to remain available for immediate reuse, without returning it to the OS. This prevents thrashing in simple loops where an arena could be created and destroyed anew on each iteration.

The dispatching of type slots to special methods (for example calling __mul__ when doing x * y) has been made faster.

Implemented separate vectorcall functions for every calling convention of builtin functions and methods. This improves performance for calls.

Handle correctly negative line offsets in the peephole optimizer. Patch by Pablo Galindo.

Remove erroneous optimization for empty set differences.

Implement :c:func:`PyBuffer_SizeFromFormat()` function (previously documented but not implemented): call :func:`struct.calcsize`. Patch by Joannah Nanjekye.

Slot functions optimize any callable with Py_TPFLAGS_METHOD_DESCRIPTOR instead of only instances of function.

The slot tp_vectorcall_offset is inherited unconditionally to support super().__call__() when the base class uses vectorcall.

:func:`threading.get_native_id` now also supports NetBSD.

Add :func:`threading.get_native_id` support for AIX. Patch by M. Felt

:func:`sum` has been optimized for boolean values.

Add --upgrade-deps to venv module. Patch by Cooper Ry Lees

pdb.Pdb supports ~/.pdbrc in Windows 7. Patch by Tim Hopper and Dan Lidral-Porter.

Updated encodings: - Removed the "tis260" encoding, which was an alias for the nonexistent "tactis" codec. - Added "mac_centeuro" as an alias for the mac_latin2 encoding.

The :class:`classmethod` decorator can now wrap other descriptors such as property objects. Adapted from a patch written by Graham Dumpleton.

Improve speed of dictview intersection by directly using set intersection logic. Patch by David Su.

Prohibit parallel running of aclose() / asend() / athrow(). Fix ag_running to reflect the actual running status of the AG.

The :func:`curses.update_lines_cols` function now returns None instead of 1 on success.

Update :exc:`TypeError` messages for :meth:`os.path.join` to include :class:`os.PathLike` objects as acceptable input types.

Add a repr for subprocess.Popen objects. Patch by Andrey Doroschenko.

pydoc now recognizes and parses HTTPS URLs. Patch by python273.

Prevent asyncio from crashing if parent __init__ is not called from a constructor of object derived from asyncio.Future.

:mod:`pdb` now uses :meth:`io.open_code` to trigger auditing events.

Allow opening pipes and other non-seekable files in append mode with :func:`open`.

Simplify the :mod:`argparse` usage message for nargs="*".

WeakSet is now registered as a collections.abc.MutableSet.

logging: change RotatingHandler namer and rotator to class-level attributes. This stops __init__ from setting them to None in the case where a subclass defines them with eponymous methods.

Add :const:`os.P_PIDFD` constant, which may be passed to :func:`os.waitid` to wait on a Linux process file descriptor.

Add :class:`asyncio.PidfdChildWatcher`, a Linux-specific child watcher implementation that polls process file descriptors.

Expose the Linux pidfd_open syscall as :func:`os.pidfd_open`.

Added constants :const:`~fcntl.F_OFD_GETLK`, :const:`~fcntl.F_OFD_SETLK` and :const:`~fcntl.F_OFD_SETLKW` to the :mod:`fcntl` module. Patch by Donghee Na.

Fixed seeking backward on an encrypted :class:`zipfile.ZipExtFile`.

Add :func:`curses.get_escdelay`, :func:`curses.set_escdelay`, :func:`curses.get_tabsize`, and :func:`curses.set_tabsize` functions - by Anthony Sottile.

Now :func:`~logging.config.fileConfig` correctly sets the .name of handlers loaded.

Add new cache_parameters() method for functools.lru_cache() to better support pickling.

asynci.ProactorEventLoop.close() now only calls signal.set_wakeup_fd() in the main thread.

The case the result of :func:`pathlib.WindowsPath.glob` matches now the case of the pattern for literal parts.

Remove misspelled attribute. The 3.8 changelog noted that this would be removed in 3.9.

Fixed erroneous equality comparison in statistics.NormalDist().

Added :const:`~os.CLD_KILLED` and :const:`~os.CLD_STOPPED` for :attr:`si_code`. Patch by Donghee Na.

Fixed a bug in :meth:`inspect.signature.bind` that was causing it to fail when handling a keyword argument with same name as positional-only parameter. Patch by Pablo Galindo.

Fixed hmac.new and hmac.HMAC to raise TypeError instead of ValueError when the digestmod parameter, now required in 3.8, is omitted. Also clarified the hmac module documentation and docstrings.

Parameters out and in of :func:`os.sendfile` was renamed to out_fd and in_fd.

Added support for setting the umask in the child process to the subprocess module on POSIX systems.

Revert PR 15522, which introduces a regression in :meth:`mimetypes.guess_type` due to improper handling of filenames as urls.

Fix __repr__ method for :class:`dataclasses.InitVar` to support typing objects, patch by Samuel Colvin.

Add missing :const:`stat.S_IFDOOR`, :const:`stat.S_IFPORT`, :const:`stat.S_IFWHT`, :func:`stat.S_ISDOOR`, :func:`stat.S_ISPORT`, and :func:`stat.S_ISWHT` values to the Python implementation of :mod:`stat`.

Clarify docstrings of pathlib suffix(es)

Nested subclasses of :class:`typing.NamedTuple` are now pickleable.

Prevent :exc:`KeyError` thrown by :func:`_encoded_words.decode` when given an encoded-word with invalid content-type encoding from propagating all the way to :func:`email.message.get`.

Deprecated the split() method in :class:`_tkinter.TkappType` in favour of the splitlist() method which has more consistent and predicable behavior.

Add :exc:`smtplib.SMTPNotSupportedError` to the :mod:`smtplib` exported names.

sendfile() used in socket and shutil modules was raising OverflowError for files >= 2GiB on 32-bit architectures. (patch by Giampaolo Rodola)

Revert the new asyncio Streams API

OS native encoding is now used for converting between Python strings and Tcl objects. This allows to display, copy and paste to clipboard emoji and other non-BMP characters. Converting strings from Tcl to Python and back now never fails (except MemoryError).

Correctly handle pause/resume reading of closed asyncio unix pipe.

Child mocks will now detect their type as either synchronous or asynchronous, asynchronous child mocks will be AsyncMocks and synchronous child mocks will be either MagicMock or Mock (depending on their parent type).

Removes _AwaitEvent from AsyncMock.

Allow the rare code that wants to send invalid http requests from the http.client library a way to do so. The fixes for bpo-30458 led to breakage for some projects that were relying on this ability to test their own behavior in the face of bad requests.

Deprecate opening :class:`~gzip.GzipFile` for writing implicitly. Always specify the mode argument for writing.

Any synchronous magic methods on an AsyncMock now return a MagicMock. Any asynchronous magic methods on a MagicMock now return an AsyncMock.

Update the length parameter of :func:`os.pread` to accept :c:type:`Py_ssize_t` instead of :c:expr:`int`.

:mod:`compileall` has a higher default recursion limit and new command-line arguments for path manipulation, symlinks handling, and multiple optimization levels.

asyncio: Fix inconsistent immediate Task cancellation

The arguments for the builtin pow function are more descriptive. They can now also be passed in as keywords.

Improve efficiency in parts of email package by changing while-pop to a for loop, using isdisjoint instead of set intersections.

Constructors of :class:`~typing.NamedTuple` and :class:`~typing.TypedDict` types now accept arbitrary keyword argument names, including "cls", "self", "typename", "_typename", "fields" and "_fields".

Add __all__ to :mod:`datetime`. Patch by Tahia Khan.

Fixed case-insensitive string comparison in :class:`sqlite3.Row` indexing.

Changes AsyncMock call count and await count to be two different counters. Now await count only counts when a coroutine has been awaited, not when it has been called, and vice-versa. Update the documentation around this.

Fix default mock name in :meth:`unittest.mock.Mock.assert_called` exceptions. Patch by Abraham Toriz Cruz.

Fix a memory leak in comparison of :class:`sqlite3.Row` objects.

_hashlib no longer calls obsolete OpenSSL initialization function with OpenSSL 1.1.0+.

Preserve subclassing in inspect.Signature.from_callable.

Names of hashing algorithms from OpenSSL are now normalized to follow Python's naming conventions. For example OpenSSL uses sha3-512 instead of sha3_512 or blake2b512 instead of blake2b.

Fix a bug in dis.findlinestarts() where it would return invalid bytecode offsets. Document that a code object's co_lnotab can contain invalid bytecode offsets.

Add slots to :mod:`asyncio` transport classes, which can reduce memory usage.

The _hashlib OpenSSL wrapper extension module is now PEP-384 compliant.

hashlib constructors now support usedforsecurity flag to signal that a hashing algorithm is not used in a security context.

Fixes a potential incorrect AttributeError exception escaping ZipFile.extract() in some unsupported input error situations.

Remove obsolete copy of PBKDF2_HMAC_fast. All supported OpenSSL versions contain a fast implementation.

The OpenSSL hashlib wrapper uses a simpler implementation. Several Macros and pointless caches are gone. The hash name now comes from OpenSSL's EVP. The algorithm name stays the same, except it is now always lower case.

Fix parent class check in protocols to correctly identify the module that provides a builtin protocol, instead of assuming they all come from the :mod:`collections.abc` module

For :mod:`asyncio`, add a new coroutine :meth:`loop.shutdown_default_executor`. The new coroutine provides an API to schedule an executor shutdown that waits on the threadpool to finish closing. Also, :func:`asyncio.run` has been updated to utilize the new coroutine. Patch by Kyle Stanley.

Fixed regression bug for socket.getsockname() for non-CAN_ISOTP AF_CAN address family sockets by returning a 1-tuple instead of string.

Update parameter names on functions in importlib.metadata matching the changes in the 0.22 release of importlib_metadata.

The os.closewalk() implementation now uses the libc fdwalk() API on platforms where it is available.

Fixes AsyncMock so it doesn't crash when used with AsyncContextManagers or AsyncIterators.

Add warning to :meth:`datetime.utctimetuple`, :meth:`datetime.utcnow` and :meth:`datetime.utcfromtimestamp` .

Allow passing a :term:`path-like object` as directory argument to the :class:`http.server.SimpleHTTPRequestHandler` class. Patch by Géry Ogam.

Update importlib.metadata with changes from importlib_metadata 0.21.

Remove __code__ check in AsyncMock that incorrectly evaluated function specs as async objects but failed to evaluate classes with __await__ but no __code__ attribute defined as async objects.

Fix reference counters in the :mod:`signal` module.

Hide internal asyncio.Stream methods: feed_eof(), feed_data(), set_exception() and set_transport().

inspect.py now uses sys.exit() instead of exit()

Added command-line interface for the :mod:`ast` module.

In :mod:`typing`, improved the __hash__ and __eq__ methods for :class:`ForwardReferences`.

Fixed :func:`inspect.getattr_static` used isinstance while it should avoid dynamic lookup.

Update :class:`importlib.machinery.BuiltinImporter` to use loader._ORIGIN instead of a hardcoded value. Patch by Donghee Na.

In importlib.metadata sync with importlib_metadata 0.20, clarifying behavior of files() and fixing issue where only one requirement was returned for requires() on dist-info packages.

weakref.WeakValueDictionary defines a local remove() function used as callback for weak references. This function was created with a closure. Modify the implementation to avoid the closure.

Added the indent option to :func:`ast.dump` which allows it to produce a multiline indented output.

Fixed a crash in the :func:`tee` iterator when re-enter it. RuntimeError is now raised in this case.

Fix a ctypes regression of Python 3.8. When a ctypes.Structure is passed by copy to a function, ctypes internals created a temporary object which had the side effect of calling the structure finalizer (__del__) twice. The Python semantics requires a finalizer to be called exactly once. Fix ctypes internals to no longer call the finalizer twice.

_json.scanstring is now up to 3x faster when there are many backslash escaped characters in the JSON string.

Prevent shutil.rmtree exception when built on non-Windows system without fd system call support, like older versions of macOS.

Semaphores and BoundedSemaphores can now release more than one waiting thread at a time.

Subscripts to the unittest.mock.call objects now receive the same chaining mechanism as any other custom attributes, so that the following usage no longer raises a TypeError:

call().foo().__getitem__('bar')

Patch by blhsing

Fix C compiler warning caused by distutils.ccompiler.CCompiler.has_function.

Add F_GETPATH command to :mod:`fcntl`.

repr() of buffered and text streams now silences only expected exceptions when get the value of "name" and "mode" attributes.

Add a total_nframe field to the traces collected by the tracemalloc module. This field indicates the original number of frames before it was truncated.

Most features of the subprocess module now work again in subinterpreters. Only preexec_fn is restricted in subinterpreters.

Fix the rusage implementation of time.process_time() to correctly report the sum of the system and user CPU time.

Fix :func:`ast.dump` when call with incompletely initialized node.

Restores instantiation of Windows IOCP event loops from the non-main thread.

Add default implementation of the :meth:`ast.NodeVisitor.visit_Constant` method which emits a deprecation warning and calls corresponding methods visit_Num(), visit_Str(), etc.

Update test_statistics.py to verify that the statistics module works well for both C and Python implementations. Patch by Donghee Na

Added a new status code to the http module: 451 UNAVAILABLE_FOR_LEGAL_REASONS

Fix a segmentation fault that appeared when comparing instances of datetime.timezone and datetime.tzinfo objects. Patch by Pablo Galindo.

Deprecate having random.seed() call hash on arbitrary types.

Add optional keyword argument exit_on_error for :class:`ArgumentParser`.

The :mod:`faulthandler` module no longer allocates its alternative stack at Python startup. Now the stack is only allocated at the first faulthandler usage.

Fix a duplicated debug message when :meth:`smtplib.SMTP.connect` is called.

venv: Don't generate unset variable warning on deactivate.

Fix dataclasses.is_dataclass when given an instance that never raises AttributeError in __getattr__. That is, an object that returns something for __dataclass_fields__ even if it's not a dataclass.

Fix socket module's socket.connect(address) function being unable to establish connection in case of interrupted system call. The problem was observed on all OSes which poll(2) system call can take only non-negative integers and -1 as a timeout value.

Optimizations for Fraction.__hash__ suggested by Tim Peters.

Fix faulthandler.register(chain=True) stack. faulthandler now allocates a dedicated stack of SIGSTKSZ*2 bytes, instead of just SIGSTKSZ bytes. Calling the previous signal handler in faulthandler signal handler uses more than SIGSTKSZ bytes of stack memory on some platforms.

Add C fastpath for statistics.NormalDist.inv_cdf() Patch by Donghee Na

Remove the deprecated method threading.Thread.isAlive(). Patch by Donghee Na.

Add Fraction.as_integer_ratio() to match the corresponding methods in bool, int, float, and decimal.

Add an xml.etree.ElementTree.indent() function for pretty-printing XML trees. Contributed by Stefan Behnel.

Fix :mod:`difflib` ? hint in diff output when dealing with tabs. Patch by Anthony Sottile.

In zipfile.Path, when adding implicit dirs, ensure that ancestral directories are added and that duplicates are excluded.

Renamed and documented test.bytecode_helper as test.support.bytecode_helper. Patch by Joannah Nanjekye.

Fix xgettext warnings in :mod:`argparse`.

:meth:`writelines` method of :class:`io.BytesIO` is now slightly faster when many small lines are passed. Patch by Sergey Fedoseev.

ensurepip now uses importlib.resources.read_binary() to read data instead of pkgutil.get_data(). Patch by Joannah Nanjekye.

Mark calendar.py helper functions as being private. The follows PEP 8 guidance to maintain the style conventions in the module and it addresses a known case of user confusion.

Add definition of THREAD_STACK_SIZE for AIX in Python/thread_pthread.h The default thread stacksize caused crashes with the default recursion limit Patch by M Felt

The logging.getLogger() API now returns the root logger when passed the name 'root', whereas previously it returned a non-root logger named 'root'. This could affect cases where user code explicitly wants a non-root logger named 'root', or instantiates a logger using logging.getLogger(__name__) in some top-level module called 'root.py'.

Fix the implementation of curses addch(str, color_pair): pass the color pair to setcchar(), instead of always passing 0 as the color pair.

Fix performance regression on regular expression parsing with huge character sets. Patch by Yann Vaginay.

The function :c:func:`PyImport_GetModule` now ensures any module it returns is fully initialized. Patch by Joannah Nanjekye.

Fix IndexError in :mod:`email` package when trying to parse invalid address fields starting with :.

The :mod:`parser` module is deprecated and will be removed in future versions of Python.

Completing WSA* error codes in :mod:`socket`.

Fixed comparisons of :class:`datetime.timedelta` and :class:`datetime.timezone`.

Synchronize importlib.metadata with importlib_metadata 0.19, improving handling of EGG-INFO files and fixing a crash when entry point names contained colons.

Correct :func:`curses.unget_wch` error message. Patch by Anthony Sottile.

Add :meth:`is_relative_to` in :class:`PurePath` to determine whether or not one path is relative to another.

Fixed :meth:`argparse.ArgumentParser.format_usage` for mutually exclusive groups. Patch by Andrew Nester.

Let math.dist() accept coordinates as sequences (or iterables) rather than just tuples.

Fixed __eq__, __lt__ etc implementations in some classes. They now return :data:`NotImplemented` for unsupported type of the other operand. This allows the other operand to play role (for example the equality comparison with :data:`~unittest.mock.ANY` will return True).

Make Activate.ps1 Powershell script static to allow for signing it.

Update wheels bundled with ensurepip (pip 19.2.3 and setuptools 41.2.0)

Bring consistency to venv shell activation scripts by always using __VENV_PROMPT__.

Allowed the pure Python implementation of :class:`datetime.timezone` to represent sub-minute offsets close to minimum and maximum boundaries, specifically in the ranges (23:59, 24:00) and (-23:59, 24:00). Patch by Ngalim Siregar

In :mod:`posix`, use ttyname_r instead of ttyname for thread safety.

Make internal attributes for statistics.NormalDist() private.

Fix NonCallableMock._call_matcher returning tuple instead of _Call object when self._spec_signature exists. Patch by Elizabeth Uselton

Make from tkinter import * import only the expected objects.

Adding a value error when an invalid value in passed to nargs Patch by Robert Leenders

Exceptions from :mod:`enum` now use the __qualname of the enum class in the exception message instead of the __name__.

Fix IndexError when parsing email headers with unexpectedly ending bare-quoted string value. Patch by Abhilash Raj.

Make json.loads faster for long strings. (Patch by Marco Paolini)

Recognize "UTF-8" as a valid value for LC_CTYPE in locale._parse_localename.

Return :exc:`NotImplemented` in Python implementation of __eq__ for :class:`~datetime.timedelta` and :class:`~datetime.time` when the other object being compared is not of the same type to match C implementation. Patch by Karthikeyan Singaravelan.

Record calls to parent when autospecced object is attached to a mock using :func:`unittest.mock.attach_mock`. Patch by Karthikeyan Singaravelan.

"python3 -m test -jN --timeout=TIMEOUT" now kills a worker process if it runs longer than TIMEOUT seconds.

Fix serialization of display name in originator or destination address fields with both encoded words and special chars.

Improve error reporting for corrupt zip files with bad zip64 extra data. Patch by Daniel Hillier.

pickle.loads() no longer raises TypeError when the buffers argument is set to None

Correct behavior for zipfile.Path.parent when the path object identifies a subdirectory.

Fix the .col_offset attribute of nested :class:`ast.BinOp` instances which had a too large value in some situations.

Fixes a possible hang when using a timeout on subprocess.run() while capturing output. If the child process spawned its own children or otherwise connected its stdout or stderr handles with another process, we could hang after the timeout was reached and our child was killed when attempting to read final output from the pipes.

Fix :func:`multiprocessing.util.get_temp_dir` finalizer: clear also the 'tempdir' configuration of the current process, so next call to get_temp_dir() will create a new temporary directory, rather than reusing the removed temporary directory.

The distutils bdist_wininst command is deprecated in Python 3.8, use bdist_wheel (wheel packages) instead.

When Enum.__str__ is overridden in a derived class, the override will be used by Enum.__format__ regardless of whether mixin classes are present.

http.client now enables TLS 1.3 post-handshake authentication for default context or if a cert_file is passed to HTTPSConnection.

Update vendorized expat version to 2.2.7.

SSLContext.post_handshake_auth = True no longer sets SSL_VERIFY_POST_HANDSHAKE verify flag for client connections. Although the option is documented as ignored for clients, OpenSSL implicitly enables cert chain validation when the flag is set.

:func:`os.sched_setaffinity` now correctly handles errors that arise during iteration over its mask argument. Patch by Brandt Bucher.

The :func:`os.getcwdb` function now uses the UTF-8 encoding on Windows, rather than the ANSI code page: see PEP 529 for the rationale. The function is no longer deprecated on Windows.

The sqlite3 module now raises TypeError, rather than ValueError, if operation argument type is not str: execute(), executemany() and calling a connection.

Fix IndexError in parsing a header value ending unexpectedly. Patch by Abhilash Raj.

The dist argument for statistics.quantiles() is now positional only. The current name doesn't reflect that the argument can be either a dataset or a distribution. Marking the parameter as positional avoids confusion and makes it possible to change the name later.

Fix a bug that was causing the :mod:`queue` module to fail if the accelerator module was not available. Patch by Pablo Galindo.

:mod:`pprint` now has support for :class:`types.SimpleNamespace`. Patch by Carl Bordum Hansen.

An :class:`~argparse.ArgumentParser` with allow_abbrev=False no longer disables grouping of short flags, such as -vv, but only disables abbreviation of long flags as documented. Patch by Zac Hatfield-Dodds.

:func:`unittest.mock.call` now preserves the order of keyword arguments in repr output. Patch by Karthikeyan Singaravelan.

Fix error unpickling datetime.time objects from Python 2 with seconds>=24. Patch by Justin Blanchard.

Add formal support for UDPLITE sockets. Support was present before, but it is now easier to detect support with hasattr(socket, 'IPPROTO_UDPLITE') and there are constants defined for each of the values needed: socket.IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV, and UDPLITE_RECV_CSCOV. Patch by Gabe Appleton.

Optimized functools.partial by using vectorcall.

:meth:`sqlite3.Connection.create_aggregate`, :meth:`sqlite3.Connection.create_function`, :meth:`sqlite3.Connection.set_authorizer`, :meth:`sqlite3.Connection.set_progress_handler` :meth:`sqlite3.Connection.set_trace_callback` methods lead to segfaults if some of these methods are called twice with an equal object but not the same. Now callbacks are stored more carefully. Patch by Aleksandr Balezin.

The obj argument of :func:`dataclasses.replace` is positional-only now.

Add the optional Linux SocketCAN Broadcast Manager constants, used as flags to configure the BCM behaviour, in the socket module. Patch by Karl Ding.

HTMLParser.unescape is removed. It was undocumented and deprecated since Python 3.4.

Add .webmanifest -> application/manifest+json to list of recognized file types and content type headers

aifc.openfp() alias to aifc.open(), sunau.openfp() alias to sunau.open(), and wave.openfp() alias to wave.open() have been removed. They were deprecated since Python 3.7.

Deprecated accepting floats with integral value (like 5.0) in :func:`math.factorial`.

_dummy_thread and dummy_threading modules have been removed. These modules were deprecated since Python 3.7 which requires threading support.

Email with single part but content-type set to multipart/* doesn't raise AttributeError anymore.

Use threadpool for reading from file for sendfile fallback mode.

Fix asyncio sendfile support when sendfile sends extra data in fallback mode.

:func:`ctypes.create_unicode_buffer()` now also supports non-BMP characters on platforms with 16-bit :c:type:`wchar_t` (for example, Windows and AIX).

In a subinterpreter, spawning a daemon thread now raises an exception. Daemon threads were never supported in subinterpreters. Previously, the subinterpreter finalization crashed with a Python fatal error if a daemon thread was still running.

Allow pure Python implementation of :mod:`pickle` to work even when the C :mod:`_pickle` module is unavailable.

Fix :mod:`lzma`: module decompresses data incompletely. When decompressing a FORMAT_ALONE format file, and it doesn't have the end marker, sometimes the last one to dozens bytes can't be output. Patch by Ma Lin.

Fix :meth:`RobotFileParser.crawl_delay` and :meth:`RobotFileParser.request_rate` to return None rather than raise :exc:`AttributeError` when no relevant rule is defined in the robots.txt file. Patch by Rémi Lapeyre.

Change the format of feature_version to be a (major, minor) tuple.

Eliminate :exc:`RuntimeError` raised by :func:`asyncio.all_tasks()` if internal tasks weak set is changed by another thread during iteration.

:class:`_pyio.IOBase` destructor now does nothing if getting the closed attribute fails to better mimic :class:`_io.IOBase` finalizer.

Fix a race condition at Python shutdown when waiting for threads. Wait until the Python thread state of all non-daemon threads get deleted (join all non-daemon threads), rather than just wait until non-daemon Python threads complete.

Default values which cannot be represented as Python objects no longer improperly represented as None in function signatures.

Added encoding and errors keyword parameters to logging.basicConfig.

Ensure cookies with expires attribute are handled in :meth:`CookieJar.make_cookies`.

Fix an unintended ValueError from :func:`subprocess.run` when checking for conflicting input and stdin or capture_output and stdout or stderr args when they were explicitly provided but with None values within a passed in **kwargs dict rather than as passed directly by name. Patch contributed by Rémi Lapeyre.

The exception message for inspect.getfile() now correctly reports the passed class rather than the builtins module.

Give math.perm() a one argument form that means the same as math.factorial().

For math.perm(n, k), let k default to n, giving the same result as factorial.

Converted _collections._count_elements to use the Argument Clinic.

Do not always create a :class:`collections.deque` in :class:`asyncio.Lock`.

Speed-up statistics.fmean() by switching from a function to a generator.

Remove Enum._convert method, deprecated in 3.8.

argparse._ActionsContainer.add_argument now throws error, if someone accidentally pass FileType class object instead of instance of FileType as type argument.

The socket module now has the :func:`socket.send_fds` and :func:`socket.recv.fds` methods. Contributed by Joannah Nanjekye, Shinya Okano and Victor Stinner.

Support running asyncio subprocesses when execution event loop in a thread on UNIX.

Lengthy email headers with UTF-8 characters are now properly encoded when they are folded. Patch by Jeffrey Kintscher.

Fixed a bug in email parsing where a message with invalid bytes in content-transfer-encoding of a multipart message can cause an AttributeError. Patch by Andrew Donnellan.

pathlib.Path instance's rename and replace methods now return the new Path instance.

:class:`urllib.request.ProxyHandler` now lowercases the keys of the passed dictionary.

Fix :func:`repr` on empty :class:`ZipInfo` object. Patch by Mickaël Schoentgen.

Email headers containing RFC2047 encoded words are parsed despite the missing whitespace, and a defect registered. Also missing trailing whitespace after encoded words is now registered as a defect.

Port test_datetime to VxWorks: skip zoneinfo tests on VxWorks

Add parser for Message-ID header and add it to default HeaderRegistry. This should prevent folding of Message-ID using RFC 2048 encoded words.

Ensure method signature is used instead of constructor signature of a class while asserting mock object against method calls. Patch by Karthikeyan Singaravelan.

posix.getgrouplist() now works correctly when the user belongs to NGROUPS_MAX supplemental groups. Patch by Jeffrey Kintscher.

Fix race condition in ThreadPoolExecutor when worker threads are created during interpreter shutdown.

Fix UserString.encode() to correctly return bytes rather than a UserString instance.

Deprecate xml.etree.ElementTree.Element.copy() in favor of copy.copy().

Patch by Gordon P. Hemsley

Fix infinite loop in email header folding logic that would be triggered when an email policy's max_line_length is not long enough to include the required markup and any values in the message. Patch by Paul Ganssle

Removed methods Element.getchildren(), Element.getiterator() and ElementTree.getiterator() and the xml.etree.cElementTree module.

Remove the old plistlib API deprecated in Python 3.4

distutils sorts source file lists so that Extension .so files build more reproducibly by default

Ignore ValueError from signal with interaction in non-main thread.

Added user, group and extra_groups parameters to the subprocess.Popen constructor. Patch by Patrick McLean.

Fix compile error when _uuid headers conflicting included.

Deprecate smtpd.MailmanProxy ready for future removal.

:attr:`shlex.shlex.punctuation_chars` is now a read-only property.

Add support for boolean actions like --foo and --no-foo to argparse. Patch contributed by Rémi Lapeyre.

Fixes a bug in :mod:`!cgi` module when a multipart/form-data request has no Content-Length header.

The abstract base classes in :mod:`collections.abc` no longer are exposed in the regular :mod:`collections` module.

Distutils won't check for rpmbuild in specified paths only.

Division handling of PurePath now returns NotImplemented instead of raising a TypeError when passed something other than an instance of str or PurePath. Patch by Roger Aiudi.

:func:`binascii.a2b_base64` is now up to 2 times faster. Patch by Sergey Fedoseev.

Add additional aliases for HP Roman 8. Patch by Michael Osipov.

Fix uuid.getnode() on platforms with '.' as MAC Addr delimiter as well fix for MAC Addr format that omits a leading 0 in MAC Addr values. Currently, AIX is the only know platform with these settings. Patch by Michael Felt.

Add :meth:`~pathlib.Path.readlink`. Patch by Girts Folkmanis.

Made :func:`urllib.parse.unquote()` accept bytes in addition to strings. Patch by Stein Karlsen.

lib2to3 now recognizes expressions after * and ** like in f(*[] or []).

Update :func:`shutil.move` function to allow for Path objects to be used as source argument. Patch by Emily Morehouse and Maxwell "5.13b" McKinnon.

Added __format__ to IPv4 and IPv6 classes. Always outputs a fully zero-padded string. Supports b/x/n modifiers (bin/hex/native format). Native format for IPv4 is bin, native format for IPv6 is hex. Also supports '#' and '_' modifiers.

Fix urllib.parse.urlparse() with numeric paths. A string like "path:80" is no longer parsed as a path but as a scheme ("path") and a path ("80").

Fixed non-deterministic behavior related to mimetypes extension mapping and module reinitialization.

Explicitly mention abc support in functools.singledispatch

Provides more details about the interaction between :c:func:`fork` and CPython's runtime, focusing just on the C-API. This includes cautions about where :c:func:`fork` should and shouldn't be called.

Modernize :mod:`email` examples from %-formatting to f-strings.

Document the fact that :exc:`RuntimeError` is raised if :meth:`os.fork` is called in a subinterpreter.

Add Brazilian Portuguese to the language switcher at Python Documentation website.

Add list of no-longer-escaped chars to re.escape documentation

Modernized the plistlib documentation

Fix example usage of :c:func:`PyModule_AddObject` to properly handle errors.

Fix a dead link in the distutils API Reference.

Warn more strongly and clearly about pickle insecurity

Added a link to dateutil.parser.isoparse in the datetime.fromisoformat documentation. Patch by Paul Ganssle

Deprecate info(), geturl(), getcode() methods in favor of the headers, url, and status properties, respectively, for HTTPResponse and addinfourl. Also deprecate the code attribute of addinfourl in favor of the status attribute. Patch by Ashwin Ramaswami

Mention frame.f_trace in :func:`sys.settrace` docs.

Make :c:func:`PyThreadState_DeleteCurrent` Internal.

Beginning edits to Whatsnew 3.8

Stop recommending getopt in the tutorial for command line argument parsing and promote argparse.

Remove implementation-specific behaviour of how venv's Deactivate works.

Fix wording of arguments for :class:`Request` in :mod:`urllib.request`

Add a brief note to indicate that any new sys.implementation required attributes must go through the PEP process.

Documented that :class:`mailbox.Maildir` constructor doesn't attempt to verify the maildir folder layout correctness. Patch by Sviatoslav Sydorenko.

Fix importlib examples to insert any newly created modules via importlib.util.module_from_spec() immediately into sys.modules instead of after calling loader.exec_module().

Thanks to Benjamin Mintz for finding the bug.

Slash ('/') is now part of syntax.

Fix PyList_GetItem index description to include 0.

Replace the dead link to the Tkinter 8.5 reference by John Shipman, New Mexico Tech, with a link to the archive.org copy.

Added possible exceptions to the description of os.chdir().

Documented that in :meth:`datetime.datetime.strptime()`, the leading zero in some two-digit formats is optional. Patch by Mike Gleen.

Add decompression pitfalls to zipfile module documentation.

In the documentation for difflib, a note was added explicitly warning that the results of SequenceMatcher's ratio method may depend on the order of the input strings.

Restructured the :mod:`datetime` docs in the interest of making them more user-friendly and improving readability. Patch by Brad Solomon.

Make C-API docs clear about what the "main" interpreter is.

The documentation for decimal string formatting using the :g specifier has been updated to reflect the correct exponential notation cutoff point. Original patch contributed by Tuomas Suutari.

Document and test that tempfile functions may accept a :term:`path-like object` for the dir argument. Patch by Anthony Sottile.

Added a note about the intended use of code in .pth files.

Fix the Doc/Makefile regarding PAPER environment variable and PDF builds

Add documentation for tkinter modules

Fix test_communicate() of test_asyncio.test_subprocess: use support.LONG_TIMEOUT (5 minutes), instead of just 1 minute.

Add timeout constants to :mod:`test.support`: :data:`~test.support.LOOPBACK_TIMEOUT`, :data:`~test.support.INTERNET_TIMEOUT`, :data:`~test.support.SHORT_TIMEOUT` and :data:`~test.support.LONG_TIMEOUT`.

test.regrtest now uses process groups in the multiprocessing mode (-jN command line option) if process groups are available: if :func:`os.setsid` and :func:`os.killpg` functions are available.

Fix a race condition in test_asyncio.test_start_tls_server_1(). Previously, there was a race condition between the test main() function which replaces the protocol and the test ServerProto protocol which sends ANSWER once it gets HELLO. Now, only the test main() function is responsible to send data, ServerProto no longer sends data.

Fix test_compileall.test_compile_dir_maxlevels() on Windows without long path support: only create 3 subdirectories instead of between 20 and 100 subdirectories.

On timeout, regrtest no longer attempts to call popen.communicate() again: it can hang until all child processes using stdout and stderr pipes completes. Kill the worker process and ignores its output. Change also the faulthandler timeout of the main process from 1 minute to 5 minutes, for Python slowest buildbots.

Fix test_gdb for Link Time Optimization (LTO) builds.

test_ssl now handles disabled TLS/SSL versions better. OpenSSL's crypto policy and run-time settings are recognized and tests for disabled versions are skipped. Tests also accept more TLS minimum_versions for platforms that override OpenSSL's default with strict settings.

The private keys for test_ssl were encrypted with 3DES in traditional PKCS#5 format. 3DES and the digest algorithm of PKCS#5 are blocked by some strict crypto policies. Use PKCS#8 format with AES256 encryption instead.

test.support now has a helper function to check for availability of a hash digest function. Several tests are refactored avoid MD5 and use SHA256 instead. Other tests are marked to use MD5 and skipped when MD5 is disabled.

Multiprocessing test test_mymanager() now also expects -SIGTERM, not only exitcode 0. BaseManager._finalize_manager() sends SIGTERM to the manager process if it takes longer than 1 second to stop, which happens on slow buildbots.

Multiprocessing tests: increase test_queue_feeder_donot_stop_onexc() timeout from 1 to 60 seconds.

Test with OpenSSL 1.1.1d

Increase code coverage for multiprocessing.shared_memory.

Add tests for json.dump(..., skipkeys=True). Patch by Donghee Na.

Enhance regrtest multiprocess timeout: write a message when killing a worker process, catch popen.kill() and popen.wait() exceptions, put a timeout on the second call to popen.communicate().

Add tests for ROT-13 codec.

Added tests for :samp:`PyDateTime_{xxx}_GET_{xxx}()` macros of the C API of the :mod:`datetime` module. Patch by Joannah Nanjekye.

Fix test_shared_memory_cleaned_after_process_termination name handling

Add :func:`test.support.catch_threading_exception`: context manager catching :class:`threading.Thread` exception using :func:`threading.excepthook`.

test_concurrent_futures now explicitly stops the ForkServer instance if it's running.

multiprocessing tests now stop the ForkServer instance if it's running: close the "alive" file descriptor to ask the server to stop and then remove its UNIX address.

test_distutils.test_build_ext() is now able to remove the temporary directory on Windows: don't import the newly built C extension ("xx") in the current process, but test it in a separated process.

test_concurrent_futures now cleans up multiprocessing to remove immediately temporary directories created by multiprocessing.util.get_temp_dir().

test_winconsoleio doesn't leak a temporary file anymore: use tempfile.TemporaryFile() to remove it when the test completes.

multiprocessing tests now explicitly call _run_finalizers() to immediately remove temporary directories created by tests.

urllib.request tests now call :func:`~urllib.request.urlcleanup` to remove temporary files created by urlretrieve() tests and to clear the _opener global variable set by urlopen() and functions calling indirectly urlopen().

Remove Lib/test/outstanding_bugs.py.

Fix test failures when IPv6 is unavailable or disabled.

Replace deprecated method "random.choose" with "random.choice" in "test_pkg_import.py".

Remove no longer necessary code from c locale coercion tests

Fix test_shutil to no longer leak temporary files.

Fix test_wsgiref.testEnviron() to no longer depend on the environment variables (don't fail if "X" variable is set).

Fix test_os.test_chown(): use os.getgroups() rather than grp.getgrall() to get groups. Rename also the test to test_chown_gid().

Add --cleanup option to python3 -m test to remove test_python_* directories of previous failed jobs. Add "make cleantest" to run python3 -m test --cleanup.

test_gdb no longer fails if it gets an "unexpected" message on stderr: it now ignores stderr. The purpose of test_gdb is to test that python-gdb.py commands work as expected, not to test gdb.

Avoid TimeoutError in test_asyncio: test_start_tls_server_1()

Fix test_asyncio ProactorLoopCtrlC: join the thread to prevent leaking a running thread and leaking a reference.

Fix :func:`test.support.catch_unraisable_exception`: its __exit__() method now ignores unraisable exception raised when clearing its unraisable attribute.

regrtest now uses :func:`sys.unraisablehook` to mark a test as "environment altered" (ENV_CHANGED) if it emits an "unraisable exception". Moreover, regrtest logs a warning in this case.

Use python3 -m test --fail-env-changed to catch unraisable exceptions in tests.

Fix assertions in test_close and test_events_mask_overflow devpoll tests.

Rewrite _PyObject_IsFreed() unit tests.

test_venv.test_multiprocessing() now explicitly calls pool.terminate() to wait until the pool completes.

Make test_ssl pass with LibreSSL. LibreSSL handles minimum and maximum TLS version differently than OpenSSL.

Make test_source_encoding.test_issue2301 implementation independent. The test will work now for both CPython and IronPython.

Update test.test_importlib.test_abc to test find_spec().

Modify the test_uuid logic to test when a program is available AND can be used to obtain a MACADDR as basis for an UUID. Patch by M. Felt

Fallback to a default reason when :func:`unittest.skip` is uncalled. Patch by Naitree Zhu.

On Windows, build scripts will now recognize and use python.exe from an active virtual env.

Fix _hashlib build when Blake2 is disabled, but OpenSSL supports it.

Misc/python-config.in now uses getvar() for all still existing sysconfig.get_config_var() calls. Patch by Joannah Nanjekye.

Fix stdatomic.h header check for ICC compiler: the ICC implementation lacks atomic_uintptr_t type which is needed by Python.

In Solaris family, we must be sure to use -D_REENTRANT. Patch by Jesús Cea Avión.

Locate llvm-profdata and llvm-ar binaries using AC_PATH_TOOL rather than AC_PATH_TARGET_TOOL.

The :file:`.gitignore` file systematically keeps "rooted", with a non-trailing slash, all the rules that are meant to apply to files in a specific place in the repo. Previously, when the intended file to ignore happened to be at the root of the repo, we'd most often accidentally also ignore files and directories with the same name anywhere in the tree.

The :file:`Tools/unicode/makeunicodedata.py` script, which is used for converting information from the Unicode Character Database into generated code and data used by the methods of :class:`str` and by the :mod:`unicodedata` module, now handles each character's data as a dataclass with named attributes, rather than a length-18 list of different fields.

The :file:`.gitignore` file no longer applies to any files that are in fact tracked in the Git repository. Patch by Greg Price.

Change "clean" makefile target to also clean the program guided optimization (PGO) data. Previously you would have to use "make clean" and "make profile-removal", or "make clobber".

Mark some individual tests to skip when --pgo is used. The tests marked increase the PGO task time significantly and likely don't help improve optimization of the final executable.

Reduce the number of unit tests run for the PGO generation task. This speeds up the task by a factor of about 15x. Running the full unit test suite is slow. This change may result in a slightly less optimized build since not as many code branches will be executed. If you are willing to wait for the much slower build, the old behavior can be restored using './configure [..] PROFILE_TASK="-m test --pgo-extended"'. We make no guarantees as to which PGO task set produces a faster build. Users who care should run their own relevant benchmarks as results can depend on the environment, workload, and compiler tool chain.

make install no longer installs wininst-*.exe files used by distutils bdist_wininst: bdist_wininst only works on Windows.

Many :samp:`PyRun_{XXX}()` functions like :c:func:`PyRun_String` were no longer exported in libpython38.dll by mistake. Export them again to fix the ABI compatibility.

Enables use of SSE2 instructions in Windows 32-bit build.

Update optional extension module detection for AIX. ossaudiodev and spwd are not applicable for AIX, and are no longer reported as missing. 3rd-party packaging of ncurses (with ASIS support) conflicts with officially supported AIX curses library, so configure AIX to use libcurses.a. However, skip trying to build _curses_panel.

patch by M Felt

Fixes HTML Help shortcut when Windows is not installed to C drive

Ensure ntpath.realpath() correctly resolves relative paths.

Restores the internal C headers that were missing from the nuget.org and Microsoft Store packages.

Remove pythonw.exe dependency on the Microsoft C++ runtime.

Fix error message in activate.bat

Ensures pyw.exe launcher reads correct registry key.

Fixes ntpath.realpath failing on sys.executable.

Update bundled OpenSSL to 1.1.1d

Reduce overhead when using multiprocessing in a Windows virtual environment.

Allow py.exe launcher to locate installations from the Microsoft Store and improve display of active virtual environments.

The pip.ini is no longer included in the Nuget package.

Set Windows 8 as the minimum required version for API support

:func:`os.cpu_count` now returns active processors rather than maximum processors.

venv activate.bat now works when the existing variables contain double quote characters.

Prevent error calling :func:`os.path.realpath` on 'NUL'.

Fix case sensitivity in test_pathlib and test_ntpath.

Fixes distutils not finding vcruntime140.dll with only the v142 toolset installed.

Ensure command-line and unattend.xml setting override previously detected states in Windows installer.

Fixes :func:`os.stat` failing for block devices on Windows

Fixes potential crash when calling :func:`os.readlink` (or indirectly through :func:`~os.path.realpath`) on a file that is not a supported link.

Improve the implementation of winerror_to_errno().

:func:`os.dup` no longer fails for standard streams on Windows 7.

The nul file on Windows now returns True from :func:`~os.path.exists` and a valid result from :func:`os.stat` with S_IFCHR set.

Enable support for following symlinks in :func:`os.realpath`.

Treat all name surrogate reparse points on Windows in :func:`os.lstat` and other reparse points as regular files in :func:`os.stat`.

Add the module name in the formatted error message when DLL load fail happens during module import in _PyImport_FindSharedFuncptrWindows(). Patch by Srinivas Nyayapati.

Trying to import the :mod:`!crypt` module on Windows will result in an :exc:`ImportError` with a message explaining that the module isn't supported on Windows. On other platforms, if the underlying _crypt module is not available, the ImportError will include a message explaining the problem.

Fixes the icons used for file associations to the Microsoft Store package.

Fix use of registry values to launch Python from Microsoft Store app.

Fix memory leak on Windows in creating an SSLContext object or running urllib.request.urlopen('https://...').

Switch Windows Store package's pip to use bundled :file:`pip.ini` instead of :envvar:`PIP_USER` variable.

Officially drop support for creating bdist_wininst installers on non-Windows systems.

Include the FORMAT_MESSAGE_IGNORE_INSERTS flag in FormatMessageW() calls.

Fixes path for :data:`sys.executable` when running from the Microsoft Store.

Don't collect unfinished processes with subprocess._active on Windows to cleanup later. Patch by Ruslan Kuprieiev.

Removes libpython38.a from standard Windows distribution.

Update Windows builds to use SQLite 3.28.0.

On Windows, :func:`os.dup` no longer creates an inheritable fd when handling a character file.

Ensure time.tzname is correct on Windows when the active code page is set to CP_UTF7 or CP_UTF8.

Make :const:`winreg.REG_MULTI_SZ` support zero-length strings.

Replace use of :c:func:`strcasecmp` for the system function :c:func:`_stricmp`. Patch by Minmin Gong.

Add native Bluetooth RFCOMM support to socket module.

Updated OpenSSL to 1.1.1d in macOS installer.

Move Azure Pipelines to latest VM versions and make macOS tests optional

Increase the default stack size of threads from 5MB to 16MB on macOS, to match the stack size of the main thread. This avoids crashes on deep recursion in threads.

Avoid test suite failures on macOS by no longer calling resource.setrlimit to increase the process stack size limit at runtime. The runtime change is no longer needed since the interpreter is being built with a larger default stack size.

Update macOS installer to use SQLite 3.28.0.

Updated OpenSSL to 1.1.1c in macOS installer.

Stop adding newline when saving an IDLE shell window.

Add an option to toggle IDLE's cursor blink for shell, editor, and output windows. See Settings, General, Window Preferences, Cursor Blink. Patch by Zackery Spytz.

Do not try to compile IDLE shell or output windows

IDLE no longer fails when write non-encodable characters to stderr. It now escapes them with a backslash, as the regular Python interpreter. Added the errors field to the standard streams.

When exiting IDLE, catch any AttributeError. One happens when EditorWindow.close is called twice. Printing a traceback, when IDLE is run from a terminal, is useless and annoying.

To avoid problems, test_idle ignores the user config directory. It no longer tries to create or access .idlerc or any files within. Users must run IDLE to discover problems with saving settings.

IDLE no longer adds 'argv' to the user namespace when initializing it. This bug only affected 3.7.4 and 3.8.0b2 to 3.8.0b4.

Shell restart lines now fill the window width, always start with '=', and avoid wrapping unnecessarily. The line will still wrap if the included file name is long relative to the width.

To avoid occasional spurious test_idle failures on slower machines, increase the hover_delay in test_tooltip.

Properly handle user input warnings in IDLE shell. Cease turning SyntaxWarnings into SyntaxErrors.

IDLE Settings dialog now closes properly when there is no shell window.

Add mousewheel scrolling for IDLE module, path, and stack browsers. Patch by George Zhang.

Fixed completions list appearing too high or low when shown above the current line.

Refactor IDLE autocomplete and improve testing.

Reorder the Run menu. Put the most common choice, Run Module, at the top.

Improve highlight config sample with example shell interaction and better labels for shell elements.

Settings dialog no longer expands with font size.

Initialize the Customize Run dialog with the command line arguments most recently entered before. The user can optionally edit before submitting them.

Fix code context not showing the correct context when first toggled on.

Optimize code context to reduce unneeded background activity. Font and highlight changes now occur along with text changes instead of after a random delay.

Cleanup config.py by inlining RemoveFile and simplifying the handling of file in CreateConfigHandlers.

Fix tab focus traversal order for help source and custom run dialogs.

Both subprocess connection error messages now refer to the 'Startup failure' section of the IDLE doc.

Add optional line numbers for IDLE editor windows. Windows open without line numbers unless set otherwise in the General tab of the configuration dialog.

To compensate for stack frames added by IDLE and avoid possible problems with low recursion limits, add 30 to limits in the user code execution process. Subtract 30 when reporting recursion limits to make this addition mostly transparent.

Properly 'attach' search dialogs to their main window so that they behave like other dialogs and do not get hidden behind their main window.

Adjust "Zoom Height" to individual screens by momentarily maximizing the window on first use with a particular screen. Changing screen settings may invalidate the saved height. While a window is maximized, "Zoom Height" has no effect.

Make calltip reminder about '/' meaning positional-only less obtrusive by only adding it when there is room on the first line.

Add 'Run... Customized' to the Run menu to run a module with customized settings. Any 'command line arguments' entered are added to sys.argv. One can suppress the normal Shell main module restart.

Gather Format menu functions into format.py. Combine paragraph.py, rstrip.py, and format methods from editor.py.

Update Valgrind suppression file to ignore a false alarm in :c:func:`PyUnicode_Decode` when using GCC builtin strcmp().

pathfix.py: Assume all files that end on '.py' are Python scripts when working recursively.

pdb's --help and --version long options now work.

Improve ArgumentClinic converter for floats.

Remove Tools/scripts/h2py.py: use cffi to access a C API in Python.

2to3 now works when run from a zipped standard library.

Argument Clinic now uses the argument name on errors with keyword-only argument instead of their position. Patch contributed by Rémi Lapeyre.

Add option -k to pathscript.py script: preserve shebang flags. Add option -a to pathscript.py script: add flags.

Re-export some function compatibility wrappers for macros in pythonrun.h.

Provide :c:func:`Py_EnterRecursiveCall` and :c:func:`Py_LeaveRecursiveCall` as regular functions for the limited API. Previously, there were defined as macros, but these macros didn't work with the limited API which cannot access PyThreadState.recursion_depth field. Remove _Py_CheckRecursionLimit from the stable ABI.

The global variable :c:data:`PyStructSequence_UnnamedField` is now a constant and refers to a constant string.

Fixed possible leak in :c:func:`PyArg_Parse` and similar functions for format units "es#" and "et#" when the macro :c:macro:`PY_SSIZE_T_CLEAN` is not defined.

Fix a crash in :class:`weakref.proxy` objects due to incorrect lifetime management when calling some associated methods that may delete the last reference to object being referenced by the proxy. Patch by Pablo Galindo.

The _PyObject_CheckConsistency() function is now also available in release mode. For example, it can be used to debug a crash in the visit_decref() function of the GC.

Revert the removal of PyThreadState_DeleteCurrent() with documentation.

Update audioop extension module to use the stable ABI (PEP-384). Patch by Tyler Kieft.

:c:func:`!Py_SetPath` now sets :data:`sys.executable` to the program full path (:c:func:`Py_GetProgramFullPath`) rather than to the program name (:c:func:`Py_GetProgramName`).

Python ignored arguments passed to :c:func:`!Py_SetPath`, :c:func:`!Py_SetPythonHome` and :c:func:`!Py_SetProgramName`: fix Python initialization to use specified arguments.

The :c:func:`Py_UNREACHABLE` macro now calls :c:func:`Py_FatalError`.

Make dict and weakref offsets opaque for C heap types by passing the offsets through PyMemberDef

The C function PyGen_NeedsFinalizing has been removed. It was not documented, tested or used anywhere within CPython after the implementation of PEP 442. Patch by Joannah Nanjekye. (Patch by Joannah Nanjekye)

Options added by PySys_AddXOption() are now handled the same way than PyConfig.xoptions and command line -X options.

Fix a crash in PySys_SetArgvEx(0, NULL, 0).

Fix subtype_dealloc to suppress the type decref when the base type is a C heap type

Add :c:func:`!_PyObject_FunctionStr` to get a user-friendly string representation of a function-like object. Patch by Jeroen Demeyer.

The functions PyEval_CallObject, PyEval_CallFunction, PyEval_CallMethod and PyEval_CallObjectWithKeywords are deprecated. Use :c:func:`PyObject_Call` and its variants instead.

PyCFunction_Call is now a deprecated alias of :c:func:`PyObject_Call`.

The vectorcall protocol now requires that the caller passes only strings as keyword names.

The vectorcall protocol is now enabled for type objects: set tp_vectorcall to a vectorcall function to be used instead of tp_new and tp_init when calling the class itself.

Exclude Python-ast.h, ast.h and asdl.h from the limited API.

Add new function _PyObject_CallOneArg for calling an object with one positional argument.

Add :c:func:`PyConfig_SetWideStringList` function.

Add fast functions for calling methods: :c:func:`_PyObject_VectorcallMethod`, :c:func:`_PyObject_CallMethodNoArgs` and :c:func:`_PyObject_CallMethodOneArg`.

The :c:macro:`METH_FASTCALL` calling convention has been documented.

The new function :c:func:`!PyCode_NewWithPosOnlyArgs` allows to create code objects like :c:func:`!PyCode_New`, but with an extra posonlyargcount parameter for indicating the number of positonal-only arguments.

Fix dtrace issue introduce by bpo-36842

Add a new public :c:func:`PyObject_CallNoArgs` function to the C API: call a callable Python object without any arguments. It is the most efficient way to call a callback without any argument. On x86-64, for example, PyObject_CallFunctionObjArgs(func, NULL) allocates 960 bytes on the stack per call, whereas PyObject_CallNoArgs(func) only allocates 624 bytes per call.

Fix the cast on error in :c:func:`PyLong_AsUnsignedLongLongMask()`.

Convert posixmodule.c statically allocated types DirEntryType and ScandirIteratorType to heap-allocated types.

Use singular/plural noun in error message when instantiating an abstract class with non-overridden abstract method(s).