Changelog

Python 3.11.15 final

Release date: 2026-03-03

Security

  • gh-144125: BytesGenerator will now refuse to serialize (write) headers that are unsafely folded or delimited; see verify_generated_headers. (Contributed by Bas Bloemsaat and Petr Viktorin in gh-121650).

  • gh-143935: Fixed a bug in the folding of comments when flattening an email message using a modern email policy. Comments consisting of a very long sequence of non-foldable characters could trigger a forced line wrap that omitted the required leading space on the continuation line, causing the remainder of the comment to be interpreted as a new header field. This enabled header injection with carefully crafted inputs.

  • gh-143925: Reject control characters in data: URL media types.

  • gh-143919: Reject control characters in http.cookies.Morsel fields and values.

  • gh-143916: Reject C0 control characters within wsgiref.headers.Headers fields, values, and parameters.

  • gh-142145: Remove quadratic behavior in xml.minidom node ID cache clearing. In order to do this without breaking existing users, we also add the ownerDocument attribute to xml.dom.minidom elements and attributes created by directly instantiating the Element or Attr class. Note that this way of creating nodes is not supported; creator functions like xml.dom.Document.documentElement() should be used instead.

  • gh-137836: Add support of the “plaintext” element, RAWTEXT elements “xmp”, “iframe”, “noembed” and “noframes”, and optionally RAWTEXT element “noscript” in html.parser.HTMLParser.

  • gh-136063: email.message: ensure linear complexity for legacy HTTP parameters parsing. Patch by Bénédikt Tran.

  • gh-136065: Fix quadratic complexity in os.path.expandvars().

  • gh-119451: Fix a potential memory denial of service in the http.client module. When connecting to a malicious server, it could cause an arbitrary amount of memory to be allocated. This could have led to symptoms including a MemoryError, swapping, out of memory (OOM) killed processes or containers, or even system crashes.

  • gh-119452: Fix a potential memory denial of service in the http.server module. When a malicious user is connected to the CGI server on Windows, it could cause an arbitrary amount of memory to be allocated. This could have led to symptoms including a MemoryError, swapping, out of memory (OOM) killed processes or containers, or even system crashes.

  • gh-119342: Fix a potential memory denial of service in the plistlib module. When reading a Plist file received from untrusted source, it could cause an arbitrary amount of memory to be allocated. This could have led to symptoms including a MemoryError, swapping, out of memory (OOM) killed processes or containers, or even system crashes.

Library

Core and Builtins

  • gh-120384: Fix an array out of bounds crash in list_ass_subscript, which could be invoked via some specificly tailored input: including concurrent modification of a list object, where one thread assigns a slice and another clears it.

  • gh-120298: Fix use-after free in list_richcompare_impl which can be invoked via some specificly tailored evil input.

Python 3.11.14 final

Release date: 2025-10-09

Security

  • gh-139700: Check consistency of the zip64 end of central directory record. Support records with “zip64 extensible data” if there are no bytes prepended to the ZIP file.

  • gh-139400: xml.parsers.expat: Make sure that parent Expat parsers are only garbage-collected once they are no longer referenced by subparsers created by ExternalEntityParserCreate(). Patch by Sebastian Pipping.

  • gh-135661: Fix parsing start and end tags in html.parser.HTMLParser according to the HTML5 standard.

    • Whitespaces no longer accepted between </ and the tag name. E.g. </ script> does not end the script section.

    • Vertical tabulation (\v) and non-ASCII whitespaces no longer recognized as whitespaces. The only whitespaces are \t\n\r\f and space.

    • Null character (U+0000) no longer ends the tag name.

    • Attributes and slashes after the tag name in end tags are now ignored, instead of terminating after the first > in quoted attribute value. E.g. </script/foo=">"/>.

    • Multiple slashes and whitespaces between the last attribute and closing > are now ignored in both start and end tags. E.g. <a foo=bar/ //>.

    • Multiple = between attribute name and value are no longer collapsed. E.g. <a foo==bar> produces attribute “foo” with value “=bar”.

  • gh-135661: Fix CDATA section parsing in html.parser.HTMLParser according to the HTML5 standard: ] ]> and ]] > no longer end the CDATA section. Add private method _set_support_cdata() which can be used to specify how to parse <[CDATA[ — as a CDATA section in foreign content (SVG or MathML) or as a bogus comment in the HTML namespace.

  • gh-102555: Fix comment parsing in html.parser.HTMLParser according to the HTML5 standard. --!> now ends the comment. -- > no longer ends the comment. Support abnormally ended empty comments <--> and <--->.

  • gh-135462: Fix quadratic complexity in processing specially crafted input in html.parser.HTMLParser. End-of-file errors are now handled according to the HTML5 specs – comments and declarations are automatically closed, tags are ignored.

  • gh-118350: Fix support of escapable raw text mode (elements “textarea” and “title”) in html.parser.HTMLParser.

  • gh-86155: html.parser.HTMLParser.close() no longer loses data when the <script> tag is not closed. Patch by Waylan Limberg.

Library

  • gh-139312: Upgrade bundled libexpat to 2.7.3

  • gh-138998: Update bundled libexpat to 2.7.2

  • gh-130577: tarfile now validates archives to ensure member offsets are non-negative. (Contributed by Alexander Enrique Urieles Nieto in gh-130577.)

  • gh-135374: Update the bundled copy of setuptools to 79.0.1.

Python 3.11.13 final

Release date: 2025-06-03

Security

  • gh-135034: Fixes multiple issues that allowed tarfile extraction filters (filter="data" and filter="tar") to be bypassed using crafted symlinks and hard links.

    Addresses CVE 2024-12718, CVE 2025-4138, CVE 2025-4330, and CVE 2025-4517.

  • gh-133767: Fix use-after-free in the “unicode-escape” decoder with a non-“strict” error handler.

  • gh-128840: Short-circuit the processing of long IPv6 addresses early in ipaddress to prevent excessive memory consumption and a minor denial-of-service.

Library

Python 3.11.12 final

Release date: 2025-04-08

Security

  • gh-131809: Update bundled libexpat to 2.7.1

  • gh-131261: Upgrade to libexpat 2.7.0

  • gh-105704: When using urllib.parse.urlsplit() and urllib.parse.urlparse() host parsing would not reject domain names containing square brackets ([ and ]). Square brackets are only valid for IPv6 and IPvFuture hosts according to RFC 3986 Section 3.2.2.

  • gh-121284: Fix bug in the folding of rfc2047 encoded-words when flattening an email message using a modern email policy. Previously when an encoded-word was too long for a line, it would be decoded, split across lines, and re-encoded. But commas and other special characters in the original text could be left unencoded and unquoted. This could theoretically be used to spoof header lines using a carefully constructed encoded-word if the resulting rendered email was transmitted or re-parsed.

  • gh-80222: Fix bug in the folding of quoted strings when flattening an email message using a modern email policy. Previously when a quoted string was folded so that it spanned more than one line, the surrounding quotes and internal escapes would be omitted. This could theoretically be used to spoof header lines using a carefully constructed quoted string if the resulting rendered email was transmitted or re-parsed.

  • gh-119511: Fix a potential denial of service in the imaplib module. When connecting to a malicious server, it could cause an arbitrary amount of memory to be allocated. On many systems this is harmless as unused virtual memory is only a mapping, but if this hit a virtual address size limit it could lead to a MemoryError or other process crash. On unusual systems or builds where all allocated memory is touched and backed by actual ram or storage it could’ve consumed resources doing so until similarly crashing.

Library

  • gh-127257: In ssl, system call failures that OpenSSL reports using ERR_LIB_SYS are now raised as OSError.

Documentation

  • gh-121277: Writers of CPython’s documentation can now use next as the version for the versionchanged, versionadded, deprecated directives.

C API

  • gh-106883: Disable GC during the _PyThread_CurrentFrames() and _PyThread_CurrentExceptions() calls to avoid the interpreter to deadlock.

Python 3.11.11 final

Release date: 2024-12-03

Tools/Demos

  • gh-123418: Update GitHub CI workflows to use OpenSSL 3.0.15 and multissltests to use 3.0.15, 3.1.7, and 3.2.3.

Tests

  • gh-125041: Re-enable skipped tests for zlib on the s390x architecture: only skip checks of the compressed bytes, which can be different between zlib’s software implementation and the hardware-accelerated implementation.

Security

  • gh-126623: Upgrade libexpat to 2.6.4

  • gh-122792: Changed IPv4-mapped ipaddress.IPv6Address to consistently use the mapped IPv4 address value for deciding properties. Properties which have their behavior fixed are is_multicast, is_reserved, is_link_local, is_global, and is_unspecified.

Library

  • gh-124651: Properly quote template strings in venv activation scripts.

Python 3.11.10 final

Release date: 2024-09-07

Windows

  • gh-123418: Updated Windows build to use OpenSSL 3.0.15.

  • gh-119690: Fixes data type confusion in audit event raised by _winapi.CreateNamedPipe.

Security

  • gh-123678: Upgrade libexpat to 2.6.3

  • gh-121957: Fixed missing audit events around interactive use of Python, now also properly firing for python -i, as well as for python -m asyncio. The event in question is cpython.run_stdin.

  • gh-122133: Authenticate the socket connection for the socket.socketpair() fallback on platforms where AF_UNIX is not available like Windows.

    Patch by Gregory P. Smith <greg@krypto.org> and Seth Larson <seth@python.org>. Reported by Ellie <el@horse64.org>

  • gh-121285: Remove backtracking from tarfile header parsing for hdrcharset, PAX, and GNU sparse headers.

  • gh-118486: os.mkdir() on Windows now accepts mode of 0o700 to restrict the new directory to the current user. This fixes CVE-2024-4030 affecting tempfile.mkdtemp() in scenarios where the base temporary directory is more permissive than the default.

  • gh-116741: Update bundled libexpat to 2.6.2

Library

Core and Builtins

  • gh-112275: A deadlock involving pystate.c’s HEAD_LOCK in posixmodule.c at fork is now fixed. Patch by ChuBoning based on previous Python 3.12 fix by Victor Stinner.

  • gh-109120: Added handle of incorrect star expressions, e.g f(3, *). Patch by Grigoryev Semyon

Python 3.11.9 final

Release date: 2024-04-02

Security

Core and Builtins

  • gh-116296: Fix possible refleak in object.__reduce__() internal error handling.

  • gh-116034: Fix location of the error on a failed assertion.

  • gh-115823: Properly calculate error ranges in the parser when raising SyntaxError exceptions caused by invalid byte sequences. Patch by Pablo Galindo

  • gh-112087: For an empty reverse iterator for list will be reduced to reversed(). Patch by Donghee Na.

  • gh-115011: Setters for members with an unsigned integer type now support the same range of valid values for objects that has a __index__() method as for int.

  • gh-96497: Fix incorrect resolution of mangled class variables used in assignment expressions in comprehensions.

Library

  • gh-117310: Fixed an unlikely early & extra Py_DECREF triggered crash in ssl when creating a new _ssl._SSLContext if CPython was built implausibly such that the default cipher list is empty or the SSL library it was linked against reports a failure from its C SSL_CTX_set_cipher_list() API.

  • gh-117178: Fix regression in lazy loading of self-referential modules, introduced in gh-114781.

  • gh-117084: Fix zipfile extraction for directory entries with the name containing backslashes on Windows.

  • gh-117110: Fix a bug that prevents subclasses of typing.Any to be instantiated with arguments. Patch by Chris Fu.

  • gh-90872: On Windows, subprocess.Popen.wait() no longer calls WaitForSingleObject() with a negative timeout: pass 0 ms if the timeout is negative. Patch by Victor Stinner.

  • gh-116957: configparser: Don’t leave ConfigParser values in an invalid state (stored as a list instead of a str) after an earlier read raised DuplicateSectionError or DuplicateOptionError.

  • gh-90095: Ignore empty lines and comments in .pdbrc

  • gh-116764: Restore support of None and other false values in urllib.parse functions parse_qs() and parse_qsl(). Also, they now raise a TypeError for non-zero integers and non-empty sequences.

  • gh-116811: In PathFinder.invalidate_caches, delegate to MetadataPathFinder.invalidate_caches.

  • gh-116600: Fix repr() for global Flag members.

  • gh-116484: Change automatically generated tkinter.Checkbutton widget names to avoid collisions with automatically generated tkinter.ttk.Checkbutton widget names within the same parent widget.

  • gh-116401: Fix blocking os.fwalk() and shutil.rmtree() on opening named pipe.

  • gh-116143: Fix a race in pydoc _start_server, eliminating a window in which _start_server can return a thread that is “serving” but without a docserver set.

  • gh-116325: typing: raise SyntaxError instead of AttributeError on forward references as empty strings.

  • gh-90535: Fix support of interval values > 1 in logging.TimedRotatingFileHandler for when='MIDNIGHT' and when='Wx'.

  • gh-115978: Disable preadv(), readv(), pwritev(), and writev() on WASI.

    Under wasmtime for WASI 0.2, these functions don’t pass test_posix (https://github.com/bytecodealliance/wasmtime/issues/7830).

  • gh-88352: Fix the computation of the next rollover time in the logging.TimedRotatingFileHandler handler. computeRollover() now always returns a timestamp larger than the specified time and works correctly during the DST change. doRollover() no longer overwrite the already rolled over file, saving from data loss when run at midnight or during repeated time at the DST change.

  • gh-87115: Set __main__.__spec__ to None when running a script with pdb

  • gh-76511: Fix UnicodeEncodeError in email.Message.as_string() that results when a message that claims to be in the ascii character set actually has non-ascii characters. Non-ascii characters are now replaced with the U+FFFD replacement character, like in the replace error handler.

  • gh-75988: Fixed unittest.mock.create_autospec() to pass the call through to the wrapped object to return the real result.

  • gh-115881: Fix issue where ast.parse() would incorrectly flag conditional context managers (such as with (x() if y else z()): ...) as invalid syntax if feature_version=(3, 8) was passed. This reverts changes to the grammar made as part of gh-94949.

  • gh-115886: Fix silent truncation of the name with an embedded null character in multiprocessing.shared_memory.SharedMemory.

  • gh-115809: Improve algorithm for computing which rolled-over log files to delete in logging.TimedRotatingFileHandler. It is now reliable for handlers without namer and with arbitrary deterministic namer that leaves the datetime part in the file name unmodified.

  • gh-74668: urllib.parse functions parse_qs() and parse_qsl() now support bytes arguments containing raw and percent-encoded non-ASCII data.

  • gh-67044: csv.writer() now always quotes or escapes '\r' and '\n', regardless of lineterminator value.

  • gh-115712: csv.writer() now quotes empty fields if delimiter is a space and skipinitialspace is true and raises exception if quoting is not possible.

  • gh-115618: Fix improper decreasing the reference count for None argument in property methods getter(), setter() and deleter().

  • gh-115570: A DeprecationWarning is no longer omitted on access to the __doc__ attributes of the deprecated typing.io and typing.re pseudo-modules.

  • gh-112006: Fix inspect.unwrap() for types with the __wrapper__ data descriptor.

  • gh-101293: Support callables with the __call__() method and types with __new__() and __init__() methods set to class methods, static methods, bound methods, partial functions, and other types of methods and descriptors in inspect.Signature.from_callable().

  • gh-115392: Fix a bug in doctest where incorrect line numbers would be reported for decorated functions.

  • gh-114563: Fix several format() bugs when using the C implementation of Decimal: * memory leak in some rare cases when using the z format option (coerce negative 0) * incorrect output when applying the z format option to type F (fixed-point with capital NAN / INF) * incorrect output when applying the # format option (alternate form)

  • gh-115197: urllib.request no longer resolves the hostname before checking it against the system’s proxy bypass list on macOS and Windows.

  • gh-115198: Fix support of Docutils >= 0.19 in distutils.

  • gh-115165: Most exceptions are now ignored when attempting to set the __orig_class__ attribute on objects returned when calling typing generic aliases (including generic aliases created using typing.Annotated). Previously only AttributeError was ignored. Patch by Dave Shawley.

  • gh-115133: Fix tests for XMLPullParser with Expat 2.6.0.

  • gh-115059: io.BufferedRandom.read1() now flushes the underlying write buffer.

  • gh-79382: Trailing ** no longer allows to match files and non-existing paths in recursive glob().

  • gh-114763: Protect modules loaded with importlib.util.LazyLoader from race conditions when multiple threads try to access attributes before the loading is complete.

  • gh-97959: Fix rendering class methods, bound methods, method and function aliases in pydoc. Class methods no longer have “method of builtins.type instance” note. Corresponding notes are now added for class and unbound methods. Method and function aliases now have references to the module or the class where the origin was defined if it differs from the current. Bound methods are now listed in the static methods section. Methods of builtin classes are now supported as well as methods of Python classes.

  • gh-112281: Allow creating union of types for typing.Annotated with unhashable metadata.

  • gh-111775: Fix importlib.resources.simple.ResourceHandle.open() for text mode, added missed stream argument.

  • gh-90095: Make .pdbrc and -c work with any valid pdb commands.

  • gh-107155: Fix incorrect output of help(x) where x is a lambda function, which has an __annotations__ dictionary attribute with a "return" key.

  • gh-105866: Fixed _get_slots bug which caused error when defining dataclasses with slots and a weakref_slot.

  • gh-60346: Fix ArgumentParser inconsistent with parse_known_args.

  • gh-100985: Update HTTPSConnection to consistently wrap IPv6 Addresses when using a proxy.

  • gh-100884: email: fix misfolding of comma in address-lists over multiple lines in combination with unicode encoding.

  • gh-95782: Fix io.BufferedReader.tell(), io.BufferedReader.seek(), _pyio.BufferedReader.tell(), io.BufferedRandom.tell(), io.BufferedRandom.seek() and _pyio.BufferedRandom.tell() being able to return negative offsets.

  • gh-96310: Fix a traceback in argparse when all options in a mutually exclusive group are suppressed.

  • gh-93205: Fixed a bug in logging.handlers.TimedRotatingFileHandler where multiple rotating handler instances pointing to files with the same name but different extensions would conflict and not delete the correct files.

  • bpo-44865: Add missing call to localization function in argparse.

  • bpo-43952: Fix multiprocessing.connection.Listener.accept() to accept empty bytes as authkey. Not accepting empty bytes as key causes it to hang indefinitely.

  • bpo-42125: linecache: get module name from __spec__ if available. This allows getting source code for the __main__ module when a custom loader is used.

  • gh-66543: Make mimetypes.guess_type() properly parsing of URLs with only a host name, URLs containing fragment or query, and filenames with only a UNC sharepoint on Windows. Based on patch by Dong-hee Na.

  • bpo-33775: Add ‘default’ and ‘version’ help text for localization in argparse.

Documentation

Tests

  • gh-83434: Disable JUnit XML output (--junit-xml=FILE command line option) in regrtest when hunting for reference leaks (-R option). Patch by Victor Stinner.

  • gh-117187: Fix XML tests for vanilla Expat <2.6.0.

  • gh-115979: Update test_importlib so that it passes under WASI SDK 21.

  • gh-116307: Added import helper isolated_modules as CleanImport does not remove modules imported during the context.

  • gh-115720: Leak tests (-R, --huntrleaks) now show a summary of the number of leaks found in each iteration.

  • gh-115122: Add --bisect option to regrtest test runner: run failed tests with test.bisect_cmd to identify failing tests. Patch by Victor Stinner.

  • gh-115596: Fix ProgramPriorityTests in test_os permanently changing the process priority.

  • gh-115198: Fix test_check_metadata_deprecate in distutils tests with a newer Docutils.

Build

  • gh-116313: Get WASI builds to work under wasmtime 18 w/ WASI 0.2/preview2 primitives.

  • gh-115167: Avoid vendoring vcruntime140_threads.dll when building with Visual Studio 2022 version 17.8.

Windows

  • gh-116773: Fix instances of <_overlapped.Overlapped object at 0xXXX> still has pending operation at deallocation, the process may crash.

  • gh-91227: Fix the asyncio ProactorEventLoop implementation so that sending a datagram to an address that is not listening does not prevent receiving any more datagrams.

  • gh-115554: The installer now has more strict rules about updating the Python Launcher for Windows. In general, most users only have a single launcher installed and will see no difference. When multiple launchers have been installed, the option to install the launcher is disabled until all but one have been removed. Downgrading the launcher (which was never allowed) is now more obviously blocked.

  • gh-115543: Python Launcher for Windows can now detect Python 3.13 when installed from the Microsoft Store, and will install Python 3.12 by default when PYLAUNCHER_ALLOW_INSTALL is set.

  • gh-115009: Update Windows installer to use SQLite 3.45.1.

IDLE

  • gh-88516: On macOS show a proxy icon in the title bar of editor windows to match platform behaviour.

Tools/Demos

  • gh-113516: Don’t set LDSHARED when building for WASI.

C API

  • gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windows 64-bit platforms.

Python 3.11.8 final

Release date: 2024-02-06

Security

  • gh-113659: Skip .pth files with names starting with a dot or hidden file attribute.

Core and Builtins

  • gh-114887: Changed socket type validation in create_datagram_endpoint() to accept all non-stream sockets. This fixes a regression in compatibility with raw sockets.

  • gh-114388: Fix a RuntimeWarning emitted when assign an integer-like value that is not an instance of int to an attribute that corresponds to a C struct member of type T_UINT and T_ULONG. Fix a double RuntimeWarning emitted when assign a negative integer value to an attribute that corresponds to a C struct member of type T_UINT.

  • gh-89811: Check for a valid tp_version_tag before performing bytecode specializations that rely on this value being usable.

  • gh-113602: Fix an error that was causing the parser to try to overwrite existing errors and crashing in the process. Patch by Pablo Galindo

  • gh-113566: Fix a 3.11-specific crash when the repr of a Future is requested after the module has already been garbage-collected.

  • gh-106905: Use per AST-parser state rather than global state to track recursion depth within the AST parser to prevent potential race condition due to simultaneous parsing.

    The issue primarily showed up in 3.11 by multithreaded users of ast.parse(). In 3.12 a change to when garbage collection can be triggered prevented the race condition from occurring.

  • gh-112716: Fix SystemError in the import statement and in __reduce__() methods of builtin types when __builtins__ is not a dict.

  • gh-105967: Workaround a bug in Apple’s macOS platform zlib library where zlib.crc32() and binascii.crc32() could produce incorrect results on multi-gigabyte inputs. Including when using zipfile on zips containing large data.

  • gh-94606: Fix UnicodeEncodeError when email.message.get_payload() reads a message with a Unicode surrogate character and the message content is not well-formed for surrogateescape encoding. Patch by Sidney Markowitz.

Library

  • gh-114965: Update bundled pip to 24.0

  • gh-114959: tarfile no longer ignores errors when trying to extract a directory on top of a file.

  • gh-109475: Fix support of explicit option value “–” in argparse (e.g. --option=--).

  • gh-110190: Fix ctypes structs with array on Windows ARM64 platform by setting MAX_STRUCT_SIZE to 32 in stgdict. Patch by Diego Russo

  • gh-113280: Fix a leak of open socket in rare cases when error occurred in ssl.SSLSocket creation.

  • gh-77749: email.policy.EmailPolicy.fold() now always encodes non-ASCII characters in headers if utf8 is false.

  • gh-114492: Make the result of termios.tcgetattr() reproducible on Alpine Linux. Previously it could leave a random garbage in some fields.

  • gh-75128: Ignore an OSError in asyncio.BaseEventLoop.create_server() when IPv6 is available but the interface cannot actually support it.

  • gh-114257: Dismiss the FileNotFound error in ctypes.util.find_library() and just return None on Linux.

  • gh-101438: Avoid reference cycle in ElementTree.iterparse. The iterator returned by ElementTree.iterparse may hold on to a file descriptor. The reference cycle prevented prompt clean-up of the file descriptor if the returned iterator was not exhausted.

  • gh-104522: OSError raised when run a subprocess now only has filename attribute set to cwd if the error was caused by a failed attempt to change the current directory.

  • gh-109534: Fix a reference leak in asyncio.selector_events.BaseSelectorEventLoop when SSL handshakes fail. Patch contributed by Jamie Phan.

  • gh-114077: Fix possible OverflowError in socket.socket.sendfile() when pass count larger than 2 GiB on 32-bit platform.

  • gh-114014: Fixed a bug in fractions.Fraction where an invalid string using d in the decimals part creates a different error compared to other invalid letters/characters. Patch by Jeremiah Gabriel Pascual.

  • gh-113951: Fix the behavior of tag_unbind() methods of tkinter.Text and tkinter.Canvas classes with three arguments. Previously, widget.tag_unbind(tag, sequence, funcid) destroyed the current binding for sequence, leaving sequence unbound, and deleted the funcid command. Now it removes only funcid from the binding for sequence, keeping other commands, and deletes the funcid command. It leaves sequence unbound only if funcid was the last bound command.

  • gh-113877: Fix tkinter method winfo_pathname() on 64-bit Windows.

  • gh-113781: Silence unraisable AttributeError when warnings are emitted during Python finalization.

  • gh-113594: Fix UnicodeEncodeError in email when re-fold lines that contain unknown-8bit encoded part followed by non-unknown-8bit encoded part.

  • gh-113538: In asyncio.StreamReaderProtocol.connection_made(), there is callback that logs an error if the task wrapping the “connected callback” fails. This callback would itself fail if the task was cancelled. Prevent this by checking whether the task was cancelled first. If so, close the transport but don’t log an error.

  • gh-85567: Fix resource warnings for unclosed files in pickle and pickletools command line interfaces.

  • gh-101225: Increase the backlog for multiprocessing.connection.Listener objects created by multiprocessing.manager and multiprocessing.resource_sharer to significantly reduce the risk of getting a connection refused error when creating a multiprocessing.connection.Connection to them.

  • gh-113543: Make sure that webbrowser.MacOSXOSAScript sends webbrowser.open audit event.

  • gh-113028: When a second reference to a string appears in the input to pickle, and the Python implementation is in use, we are guaranteed that a single copy gets pickled and a single object is shared when reloaded. Previously, in protocol 0, when a string contained certain characters (e.g. newline) it resulted in duplicate objects.

  • gh-113421: Fix multiprocessing logger for %(filename)s.

  • gh-113358: Fix rendering tracebacks for exceptions with a broken __getattr__.

  • gh-113214: Fix an AttributeError during asyncio SSL protocol aborts in SSL-over-SSL scenarios.

  • gh-113246: Update bundled pip to 23.3.2.

  • gh-113199: Make http.client.HTTPResponse.read1 and http.client.HTTPResponse.readline close IO after reading all data when content length is known. Patch by Illia Volochii.

  • gh-113188: Fix shutil.copymode() and shutil.copystat() on Windows. Previously they worked differenly if dst is a symbolic link: they modified the permission bits of dst itself rather than the file it points to if follow_symlinks is true or src is not a symbolic link, and did not modify the permission bits if follow_symlinks is false and src is a symbolic link.

  • gh-61648: Detect line numbers of properties in doctests.

  • gh-112559: signal.signal() and signal.getsignal() no longer call repr on callable handlers. asyncio.run() and asyncio.Runner.run() no longer call repr on the task results. Patch by Yilei Yang.

  • gh-110190: Fix ctypes structs with array on PPC64LE platform by setting MAX_STRUCT_SIZE to 64 in stgdict. Patch by Diego Russo.

  • gh-79429: Ignore FileNotFoundError when remove a temporary directory in the multiprocessing finalizer.

  • gh-79325: Fix an infinite recursion error in tempfile.TemporaryDirectory() cleanup on Windows.

  • gh-110190: Fix ctypes structs with array on Arm platform by setting MAX_STRUCT_SIZE to 32 in stgdict. Patch by Diego Russo.

  • gh-81194: Fix a crash in socket.if_indextoname() with specific value (UINT_MAX). Fix an integer overflow in socket.if_indextoname() on 64-bit non-Windows platforms.

  • gh-75666: Fix the behavior of tkinter widget’s unbind() method with two arguments. Previously, widget.unbind(sequence, funcid) destroyed the current binding for sequence, leaving sequence unbound, and deleted the funcid command. Now it removes only funcid from the binding for sequence, keeping other commands, and deletes the funcid command. It leaves sequence unbound only if funcid was the last bound command.

  • gh-110345: Show the Tcl/Tk patchlevel (rather than version) in tkinter._test().

  • gh-109858: Protect zipfile from “quoted-overlap” zipbomb. It now raises BadZipFile when try to read an entry that overlaps with other entry or central directory.

  • gh-38807: Fix race condition in trace. Instead of checking if a directory exists and creating it, directly call os.makedirs() with the kwarg exist_ok=True.

  • gh-75705: Set unixfrom envelope in mailbox.mbox and mailbox.MMDF.

  • gh-105102: Allow ctypes.Union to be nested in ctypes.Structure when the system endianness is the opposite of the classes.

  • gh-104282: Fix null pointer dereference in lzma._decode_filter_properties() due to improper handling of BCJ filters with properties of zero length. Patch by Radislav Chugunov.

  • gh-102512: When os.fork() is called from a foreign thread (aka _DummyThread), the type of the thread in a child process is changed to _MainThread. Also changed its name and daemonic status, it can be now joined.

  • gh-91133: Fix a bug in tempfile.TemporaryDirectory cleanup, which now no longer dereferences symlinks when working around file system permission errors.

  • bpo-43153: On Windows, tempfile.TemporaryDirectory previously masked a PermissionError with NotADirectoryError during directory cleanup. It now correctly raises PermissionError if errors are not ignored. Patch by Andrei Kulakov and Ken Jin.

  • bpo-35332: The shutil.rmtree() function now ignores errors when calling os.close() when ignore_errors is True, and os.close() no longer retried after error.

  • bpo-35928: io.TextIOWrapper now correctly handles the decoding buffer after read() and write().

  • bpo-26791: shutil.move() now moves a symlink into a directory when that directory is the target of the symlink. This provides the same behavior as the mv shell command. The previous behavior raised an exception. Patch by Jeffrey Kintscher.

  • bpo-36959: Fix some error messages for invalid ISO format string combinations in strptime() that referred to directives not contained in the format string. Patch by Gordon P. Hemsley.

  • bpo-18060: Fixed a class inheritance issue that can cause segfaults when deriving two or more levels of subclasses from a base class of Structure or Union.

Documentation

  • gh-110746: Improved markup for valid options/values for methods ttk.treeview.column and ttk.treeview.heading, and for Layouts.

  • gh-95649: Document that the asyncio module contains code taken from v0.16.0 of the uvloop project, as well as the required MIT licensing information.

Tests

  • gh-109980: Fix test_tarfile_vs_tar in test_shutil for macOS, where system tar can include more information in the archive than shutil.make_archive.

  • gh-112769: The tests now correctly compare zlib version when zlib.ZLIB_RUNTIME_VERSION contains non-integer suffixes. For example zlib-ng defines the version as 1.3.0.zlib-ng.

  • gh-105089: Fix test.test_zipfile.test_core.TestWithDirectory.test_create_directory_with_write test in AIX by doing a bitwise AND of 0xFFFF on mode , so that it will be in sync with zinfo.external_attr

  • bpo-40648: Test modes that file can get with chmod() on Windows.

Build

  • gh-101778: Fix build error when there’s a dangling symlink in the directory containing ffi.h.

  • gh-112305: Fixed the check-clean-src step performed on out of tree builds to detect errant $(srcdir)/Python/frozen_modules/*.h files and recommend appropriate source tree cleanup steps to get a working build again.

  • bpo-11102: The os.major(), os.makedev(), and os.minor() functions are now available on HP-UX v3.

  • bpo-36351: Do not set ipv6type when cross-compiling.

Windows

  • gh-109991: Update Windows build to use OpenSSL 3.0.13.

  • gh-111239: Update Windows builds to use zlib v1.3.1.

  • gh-100107: The py.exe launcher will no longer attempt to run the Microsoft Store redirector when launching a script containing a /usr/bin/env shebang

  • gh-114096: Process privileges that are activated for creating directory junctions are now restored afterwards, avoiding behaviour changes in other parts of the program.

  • gh-113009: multiprocessing: On Windows, fix a race condition in Process.terminate(): no longer set the returncode attribute to always call WaitForSingleObject() in Process.wait(). Previously, sometimes the process was still running after TerminateProcess() even if GetExitCodeProcess() is not STILL_ACTIVE. Patch by Victor Stinner.

  • gh-87868: Correctly sort and remove duplicate environment variables in _winapi.CreateProcess().

  • bpo-37308: Fix mojibake in mmap.mmap when using a non-ASCII tagname argument on Windows.

macOS

  • gh-115009: Update macOS installer to use SQLite 3.45.1.

  • gh-109991: Update macOS installer to use OpenSSL 3.0.13.

  • gh-74573: Document that dbm.ndbm can silently corrupt DBM files on updates when exceeding undocumented platform limits, and can crash (segmentation fault) when reading such a corrupted file. (FB8919203)

  • gh-65701: The freeze tool doesn’t work with framework builds of Python. Document this and bail out early when running the tool with such a build.

  • gh-102362: Make sure the result of sysconfig.get_plaform() includes at least a major and minor versions, even if MACOSX_DEPLOYMENT_TARGET is set to only a major version during build to match the format expected by pip.

  • gh-110017: Disable a signal handling stress test on macOS due to a bug in macOS (FB13453490).

  • gh-109981: Use /dev/fd on macOS to determine the number of open files in test.support.os_helper.fd_count to avoid a crash with “guarded” file descriptors when probing for open files.

IDLE

  • gh-96905: In idlelib code, stop redefining built-ins ‘dict’ and ‘object’.

  • gh-72284: Improve the lists of features, editor key bindings, and shell key bingings in the IDLE doc.

  • gh-113903: Fix rare failure of test.test_idle, in test_configdialog.

  • gh-113729: Fix the “Help -> IDLE Doc” menu bug in 3.11.7 and 3.12.1.

  • gh-113269: Fix test_editor hang on macOS Catalina.

  • gh-112898: Fix processing unsaved files when quitting IDLE on macOS.

  • gh-103820: Revise IDLE bindings so that events from mouse button 4/5 on non-X11 windowing systems (i.e. Win32 and Aqua) are not mistaken for scrolling.

  • bpo-13586: Enter the selected text when opening the “Replace” dialog.

Tools/Demos

  • gh-109991: Update GitHub CI workflows to use OpenSSL 3.0.13 and multissltests to use 1.1.1w, 3.0.13, 3.1.5, and 3.2.1.

  • gh-115015: Fix a bug in Argument Clinic that generated incorrect code for methods with no parameters that use the METH_METHOD | METH_FASTCALL | METH_KEYWORDS calling convention. Only the positional parameter count was checked; any keyword argument passed would be silently accepted.

Python 3.11.7 final

Release date: 2023-12-04

Core and Builtins

  • gh-112625: Fixes a bug where a bytearray object could be cleared while iterating over an argument in the bytearray.join() method that could result in reading memory after it was freed.

  • gh-112388: Fix an error that was causing the parser to try to overwrite tokenizer errors. Patch by pablo Galindo

  • gh-112387: Fix error positions for decoded strings with backwards tokenize errors. Patch by Pablo Galindo

  • gh-112266: Change docstrings of __dict__ and __weakref__.

  • gh-109181: Speed up Traceback object creation by lazily compute the line number. Patch by Pablo Galindo

  • gh-102388: Fix a bug where iso2022_jp_3 and iso2022_jp_2004 codecs read out of bounds

  • gh-111366: Fix an issue in the codeop that was causing SyntaxError exceptions raised in the presence of invalid syntax to not contain precise error messages. Patch by Pablo Galindo

  • gh-111380: Fix a bug that was causing SyntaxWarning to appear twice when parsing if invalid syntax is encountered later. Patch by Pablo galindo

  • gh-88116: Traceback location ranges involving wide unicode characters (like emoji and asian characters) now are properly highlighted. Patch by Batuhan Taskaya and Pablo Galindo.

  • gh-94438: Fix a regression that prevented jumping across is None and is not None when debugging. Patch by Savannah Ostrowski.

  • gh-110696: Fix incorrect error message for invalid argument unpacking. Patch by Pablo Galindo

  • gh-110237: Fix missing error checks for calls to PyList_Append in _PyEval_MatchClass.

  • gh-109216: Fix possible memory leak in BUILD_MAP.

Library

  • gh-112618: Fix a caching bug relating to typing.Annotated. Annotated[str, True] is no longer identical to Annotated[str, 1].

  • gh-112509: Fix edge cases that could cause a key to be present in both the __required_keys__ and __optional_keys__ attributes of a typing.TypedDict. Patch by Jelle Zijlstra.

  • gh-94722: Fix bug where comparison between instances of DocTest fails if one of them has None as its lineno.

  • gh-112105: Make readline.set_completer_delims() work with libedit

  • gh-111942: Fix SystemError in the TextIOWrapper constructor with non-encodable “errors” argument in non-debug mode.

  • gh-109538: Issue warning message instead of having RuntimeError be displayed when event loop has already been closed at StreamWriter.__del__().

  • gh-111942: Fix crashes in io.TextIOWrapper.reconfigure() when pass invalid arguments, e.g. non-string encoding.

  • gh-111804: Remove posix.fallocate() under WASI as the underlying posix_fallocate() is not available in WASI preview2.

  • gh-111841: Fix truncating arguments on an embedded null character in os.putenv() and os.unsetenv() on Windows.

  • gh-111541: Fix doctest for SyntaxError not-builtin subclasses.

  • gh-110894: Call loop exception handler for exceptions in client_connected_cb of asyncio.start_server() so that applications can handle it. Patch by Kumar Aditya.

  • gh-111531: Fix reference leaks in bind_class() and bind_all() methods of tkinter widgets.

  • gh-111356: Added io.text_encoding(), io.DEFAULT_BUFFER_SIZE, and io.IncrementalNewlineDecoder to io.__all__.

  • gh-68166: Remove mention of not supported “vsapi” element type in tkinter.ttk.Style.element_create(). Add tests for element_create() and other ttk.Style methods. Add examples for element_create() in the documentation.

  • gh-111251: Fix _blake2 not checking for errors when initializing.

  • gh-111174: Fix crash in io.BytesIO.getbuffer() called repeatedly for empty BytesIO.

  • gh-111187: Postpone removal version for locale.getdefaultlocale() to Python 3.15.

  • gh-111159: Fix doctest output comparison for exceptions with notes.

  • gh-110910: Fix invalid state handling in asyncio.TaskGroup and asyncio.Timeout. They now raise proper RuntimeError if they are improperly used and are left in consistent state after this.

  • gh-111092: Make turtledemo run without default root enabled.

  • gh-110590: Fix a bug in _sre.compile() where TypeError would be overwritten by OverflowError when the code argument was a list of non-ints.

  • gh-65052: Prevent pdb from crashing when trying to display undisplayable objects

  • gh-110519: Deprecation warning about non-integer number in gettext now alwais refers to the line in the user code where gettext function or method is used. Previously it could refer to a line in gettext code.

  • gh-110378: contextmanager() and asynccontextmanager() context managers now close an invalid underlying generator object that yields more then one value.

  • gh-110365: Fix termios.tcsetattr() bug that was overwritting existing errors during parsing integers from term list.

  • gh-110196: Add __reduce__ method to IPv6Address in order to keep scope_id

  • gh-109747: Improve errors for unsupported look-behind patterns. Now re.error is raised instead of OverflowError or RuntimeError for too large width of look-behind pattern.

  • gh-109786: Fix possible reference leaks and crash when re-enter the __next__() method of itertools.pairwise.

  • gh-108791: Improved error handling in pdb command line interface, making it produce more concise error messages.

  • gh-73561: Omit the interface scope from an IPv6 address when used as Host header by http.client.

  • gh-86826: zipinfo now supports the full range of values in the TZ string determined by RFC 8536 and detects all invalid formats. Both Python and C implementations now raise exceptions of the same type on invalid data.

  • bpo-41422: Fixed memory leaks of pickle.Pickler and pickle.Unpickler involving cyclic references via the internal memo mapping.

  • bpo-40262: The ssl.SSLSocket.recv_into() method no longer requires the buffer argument to implement __len__ and supports buffers with arbitrary item size.

  • bpo-35191: Fix unexpected integer truncation in socket.setblocking() which caused it to interpret multiples of 2**32 as False.

Documentation

  • gh-108826: dis module command-line interface is now mentioned in documentation.

Tests

  • gh-110367: Make regrtest --verbose3 option compatible with --huntrleaks -jN options. The ./python -m test -j1 -R 3:3 --verbose3 command now works as expected. Patch by Victor Stinner.

  • gh-111309: distutils tests can now be run via unittest.

  • gh-111165: Remove no longer used functions run_unittest() and run_doctest() and class BasicTestRunner from the test.support module.

  • gh-110932: Fix regrtest if the SOURCE_DATE_EPOCH environment variable is defined: use the variable value as the random seed. Patch by Victor Stinner.

  • gh-110995: test_gdb: Fix detection of gdb built without Python scripting support. Patch by Victor Stinner.

  • gh-110918: Test case matching patterns specified by options --match, --ignore, --matchfile and --ignorefile are now tested in the order of specification, and the last match determines whether the test case be run or ignored.

  • gh-110647: Fix test_stress_modifying_handlers() of test_signal. Patch by Victor Stinner.

  • gh-103053: Fix test_tools.test_freeze on FreeBSD: run “make distclean” instead of “make clean” in the copied source directory to remove also the “python” program. Patch by Victor Stinner.

  • gh-110167: Fix a deadlock in test_socket when server fails with a timeout but the client is still running in its thread. Don’t hold a lock to call cleanup functions in doCleanups(). One of the cleanup function waits until the client completes, whereas the client could deadlock if it called addCleanup() in such situation. Patch by Victor Stinner.

  • gh-110388: Add tests for tty.

  • gh-81002: Add tests for termios.

  • gh-110267: Add tests for pickling and copying PyStructSequence objects. Patched by Xuehai Pan.

  • gh-109974: Fix race conditions in test_threading lock tests. Wait until a condition is met rather than using time.sleep() with a hardcoded number of seconds. Patch by Victor Stinner.

  • gh-109972: Split test_gdb.py file into a test_gdb package made of multiple tests, so tests can now be run in parallel. Patch by Victor Stinner.

  • gh-104736: Fix test_gdb on Python built with LLVM clang 16 on Linux ppc64le (ex: Fedora 38). Search patterns in gdb “bt” command output to detect when gdb fails to retrieve the traceback. For example, skip a test if Backtrace stopped: frame did not save the PC is found. Patch by Victor Stinner.

  • gh-108927: Fixed order dependence in running tests in the same process when a test that has submodules (e.g. test_importlib) follows a test that imports its submodule (e.g. test_importlib.util) and precedes a test (e.g. test_unittest or test_compileall) that uses that submodule.

Build

  • gh-103053: “make check-clean-src” now also checks if the “python” program is found in the source directory: fail with an error if it does exist. Patch by Victor Stinner.

  • gh-109191: Fix compile error when building with recent versions of libedit.

Windows

  • gh-110913: WindowsConsoleIO now correctly chunks large buffers without splitting up UTF-8 sequences.

  • gh-110437: Allows overriding the source of VC redistributables so that releases can be guaranteed to never downgrade between updates.

  • gh-109286: Update Windows installer to use SQLite 3.43.1.

macOS

  • gh-110950: Update macOS installer to include an upstream Tcl/Tk fix for the Secure coding is not enabled for restorable state! warning encountered in Tkinter on macOS 14 Sonoma.

  • gh-111015: Ensure that IDLE.app and Python Launcher.app are installed with appropriate permissions on macOS builds.

  • gh-109286: Update macOS installer to use SQLite 3.43.1.

  • gh-71383: Update macOS installer to include an upstream Tcl/Tk fix for the ttk::ThemeChanged error encountered in Tkinter.

  • gh-92603: Update macOS installer to include a fix accepted by upstream Tcl/Tk for a crash encountered after the first tkinter.Tk() instance is destroyed.

  • gh-99834: Update macOS installer to Tcl/Tk 8.6.13.

IDLE

  • bpo-35668: Add docstrings to the IDLE debugger module. Fix two bugs: initialize Idb.botframe (should be in Bdb); in Idb.in_rpc_code, check whether prev_frame is None before trying to use it. Greatly expand test_debugger.

C API

Python 3.11.6 final

Release date: 2023-10-02

Core and Builtins

  • gh-109351: Fix crash when compiling an invalid AST involving a named (walrus) expression.

  • gh-109207: Fix a SystemError in __repr__ of symtable entry object.

  • gh-109179: Fix bug where the C traceback display drops notes from SyntaxError.

  • gh-88943: Improve syntax error for non-ASCII character that follows a numerical literal. It now points on the invalid non-ASCII character, not on the valid numerical literal.

  • gh-108959: Fix caret placement for error locations for subscript and binary operations that involve non-semantic parentheses and spaces. Patch by Pablo Galindo

  • gh-108520: Fix multiprocessing.synchronize.SemLock.__setstate__() to properly initialize multiprocessing.synchronize.SemLock._is_fork_ctx. This fixes a regression when passing a SemLock accross nested processes.

    Rename multiprocessing.synchronize.SemLock.is_fork_ctx to multiprocessing.synchronize.SemLock._is_fork_ctx to avoid exposing it as public API.

Library

  • gh-110036: On Windows, multiprocessing Popen.terminate() now catchs PermissionError and get the process exit code. If the process is still running, raise again the PermissionError. Otherwise, the process terminated as expected: store its exit code. Patch by Victor Stinner.

  • gh-110038: Fixed an issue that caused KqueueSelector.select() to not return all the ready events in some cases when a file descriptor is registered for both read and write.

  • gh-109631: re functions such as re.findall(), re.split(), re.search() and re.sub() which perform short repeated matches can now be interrupted by user.

  • gh-109593: Avoid deadlocking on a reentrant call to the multiprocessing resource tracker. Such a reentrant call, though unlikely, can happen if a GC pass invokes the finalizer for a multiprocessing object such as SemLock.

  • gh-109613: Fix os.stat() and os.DirEntry.stat(): check for exceptions. Previously, on Python built in debug mode, these functions could trigger a fatal Python error (and abort the process) when a function succeeded with an exception set. Patch by Victor Stinner.

  • gh-109375: The pdb alias command now prevents registering aliases without arguments.

  • gh-107219: Fix a race condition in concurrent.futures. When a process in the process pool was terminated abruptly (while the future was running or pending), close the connection write end. If the call queue is blocked on sending bytes to a worker process, closing the connection write end interrupts the send, so the queue can be closed. Patch by Victor Stinner.

  • gh-50644: Attempts to pickle or create a shallow or deep copy of codecs streams now raise a TypeError. Previously, copying failed with a RecursionError, while pickling produced wrong results that eventually caused unpickling to fail with a RecursionError.

  • gh-108987: Fix _thread.start_new_thread() race condition. If a thread is created during Python finalization, the newly spawned thread now exits immediately instead of trying to access freed memory and lead to a crash. Patch by Victor Stinner.

  • gh-108843: Fix an issue in ast.unparse() when unparsing f-strings containing many quote types.

  • gh-108682: Enum: raise TypeError if super().__new__() is called from a custom __new__.

  • gh-105829: Fix concurrent.futures.ProcessPoolExecutor deadlock

  • gh-64662: Fix support for virtual tables in sqlite3.Connection.iterdump(). Patch by Aviv Palivoda.

  • gh-107913: Fix possible losses of errno and winerror values in OSError exceptions if they were cleared or modified by the cleanup code before creating the exception object.

  • gh-104372: On Linux where subprocess can use the vfork() syscall for faster spawning, prevent the parent process from blocking other threads by dropping the GIL while it waits for the vfork’ed child process exec() outcome. This prevents spawning a binary from a slow filesystem from blocking the rest of the application.

  • gh-84867: unittest.TestLoader no longer loads test cases from exact unittest.TestCase and unittest.FunctionTestCase classes.

Documentation

  • gh-109209: The minimum Sphinx version required for the documentation is now 4.2.

  • gh-105052: Update timeit doc to specify that time in seconds is just the default.

  • gh-102823: Document the return type of x // y when x and y have type float.

Tests

  • gh-110031: Skip test_threading tests using thread+fork if Python is built with Address Sanitizer (ASAN). Patch by Victor Stinner.

  • gh-110088: Fix test_asyncio timeouts: don’t measure the maximum duration, a test should not measure a CI performance. Only measure the minimum duration when a task has a timeout or delay. Add CLOCK_RES to test_asyncio.utils. Patch by Victor Stinner.

  • gh-110033: Fix test_interprocess_signal() of test_signal. Make sure that the subprocess.Popen object is deleted before the test raising an exception in a signal handler. Otherwise, Popen.__del__() can get the exception which is logged as Exception ignored in: ... and the test fails. Patch by Victor Stinner.

  • gh-109594: Fix test_timeout() of test_concurrent_futures.test_wait. Remove the future which may or may not complete depending if it takes longer than the timeout ot not. Keep the second future which does not complete before wait() timeout. Patch by Victor Stinner.

  • gh-109748: Fix test_zippath_from_non_installed_posix() of test_venv: don’t copy __pycache__/ sub-directories, because they can be modified by other Python tests running in parallel. Patch by Victor Stinner.

  • gh-103053: Skip test_freeze_simple_script() of test_tools.test_freeze if Python is built with ./configure --enable-optimizations, which means with Profile Guided Optimization (PGO): it just makes the test too slow. The freeze tool is tested by many other CIs with other (faster) compiler flags. Patch by Victor Stinner.

  • gh-109396: Fix test_socket.test_hmac_sha1() in FIPS mode. Use a longer key: FIPS mode requires at least of at least 112 bits. The previous key was only 32 bits. Patch by Victor Stinner.

  • gh-104736: Fix test_gdb on Python built with LLVM clang 16 on Linux ppc64le (ex: Fedora 38). Search patterns in gdb “bt” command output to detect when gdb fails to retrieve the traceback. For example, skip a test if Backtrace stopped: frame did not save the PC is found. Patch by Victor Stinner.

  • gh-109237: Fix test_site.test_underpth_basic() when the working directory contains at least one non-ASCII character: encode the ._pth file to UTF-8 and enable the UTF-8 Mode to use UTF-8 for the child process stdout. Patch by Victor Stinner.

  • gh-109230: Fix test_pyexpat.test_exception(): it can now be run from a directory different than Python source code directory. Before, the test failed in this case. Skip the test if Modules/pyexpat.c source is not available. Skip also the test on Python implementations other than CPython. Patch by Victor Stinner.

  • gh-109015: Fix test_asyncio, test_imaplib and test_socket tests on FreeBSD if the TCP blackhole is enabled (sysctl net.inet.tcp.blackhole). Skip the few tests which failed with ETIMEDOUT which such non standard configuration. Currently, the FreeBSD GCP image enables TCP and UDP blackhole (sysctl net.inet.tcp.blackhole=2 and sysctl net.inet.udp.blackhole=1). Patch by Victor Stinner.

  • gh-91960: Skip test_gdb if gdb is unable to retrieve Python frame objects: if a frame is <optimized out>. When Python is built with “clang -Og”, gdb can fail to retrive the frame parameter of _PyEval_EvalFrameDefault(). In this case, tests like py_bt() are likely to fail. Without getting access to Python frames, python-gdb.py is mostly clueless on retrieving the Python traceback. Moreover, test_gdb is no longer skipped on macOS if Python is built with Clang. Patch by Victor Stinner.

  • gh-108962: Skip test_tempfile.test_flags() if chflags() fails with “OSError: [Errno 45] Operation not supported” (ex: on FreeBSD 13). Patch by Victor Stinner.

  • gh-89392: Removed support of test_main() function in tests. They now always use normal unittest test runner.

  • gh-108851: Fix test_tomllib recursion tests for WASI buildbots: reduce the recursion limit and compute the maximum nested array/dict depending on the current available recursion limit. Patch by Victor Stinner.

  • gh-108851: Add get_recursion_available() and get_recursion_depth() functions to the test.support module. Patch by Victor Stinner.

  • gh-108822: regrtest now computes statistics on all tests: successes, failures and skipped. test_netrc, test_pep646_syntax and test_xml_etree now return results in their test_main() function. Patch by Victor Stinner and Alex Waygood.

  • gh-108388: Convert test_concurrent_futures to a package of 7 sub-tests. Patch by Victor Stinner.

  • gh-108388: Split test_multiprocessing_fork, test_multiprocessing_forkserver and test_multiprocessing_spawn into test packages. Each package is made of 4 sub-tests: processes, threads, manager and misc. It allows running more tests in parallel and so reduce the total test duration. Patch by Victor Stinner.

  • gh-101634: When running the Python test suite with -jN option, if a worker stdout cannot be decoded from the locale encoding report a failed testn so the exitcode is non-zero. Patch by Victor Stinner.

  • gh-100086: The Python test runner (libregrtest) now logs Python build information like “debug” vs “release” build, or LTO and PGO optimizations. Patch by Victor Stinner.

  • gh-98903: The Python test suite now fails wit exit code 4 if no tests ran. It should help detecting typos in test names and test methods.

  • gh-95027: On Windows, when the Python test suite is run with the -jN option, the ANSI code page is now used as the encoding for the stdout temporary file, rather than using UTF-8 which can lead to decoding errors. Patch by Victor Stinner.

  • gh-93353: regrtest now checks if a test leaks temporary files or directories if run with -jN option. Patch by Victor Stinner.

Build

  • gh-63760: Fix Solaris build: no longer redefine the gethostname() function. Solaris defines the function since 2005. Patch by Victor Stinner, original patch by Jakub Kulík.

  • gh-108740: Fix a race condition in make regen-all. The deepfreeze.c source and files generated by Argument Clinic are now generated or updated before generating “global objects”. Previously, some identifiers may miss depending on the order in which these files were generated. Patch by Victor Stinner.

Windows

  • gh-109991: Update Windows build to use OpenSSL 3.0.11.

  • gh-107565: Update Windows build to use OpenSSL 3.0.10.

macOS

  • gh-109991: Update macOS installer to use OpenSSL 3.0.11.

Tools/Demos

  • gh-109991: Update GitHub CI workflows to use OpenSSL 3.0.11 and multissltests to use 1.1.1w, 3.0.11, and 3.1.3.

Python 3.11.5 final

Release date: 2023-08-24

Security

  • gh-108310: Fixed an issue where instances of ssl.SSLSocket were vulnerable to a bypass of the TLS handshake and included protections (like certificate verification) and treating sent unencrypted data as if it were post-handshake TLS encrypted data. Security issue reported as CVE-2023-40217 by Aapo Oksman. Patch by Gregory P. Smith.

Core and Builtins

  • gh-104432: Fix potential unaligned memory access on C APIs involving returned sequences of char * pointers within the grp and socket modules. These were revealed using a -fsaniziter=alignment build on ARM macOS. Patch by Christopher Chavez.

  • gh-77377: Ensure that multiprocessing synchronization objects created in a fork context are not sent to a different process created in a spawn context. This changes a segfault into an actionable RuntimeError in the parent process.

  • gh-106092: Fix a segmentation fault caused by a use-after-free bug in frame_dealloc when the trashcan delays the deallocation of a PyFrameObject.

  • gh-106719: No longer suppress arbitrary errors in the __annotations__ getter and setter in the type and module types.

  • gh-106723: Propagate frozen_modules to multiprocessing spawned process interpreters.

  • gh-105979: Fix crash in _imp.get_frozen_object() due to improper exception handling.

  • gh-105840: Fix possible crashes when specializing function calls with too many __defaults__.

  • gh-105588: Fix an issue that could result in crashes when compiling malformed ast nodes.

  • gh-105375: Fix bugs in the builtins module where exceptions could end up being overwritten.

  • gh-105375: Fix bug in the compiler where an exception could end up being overwritten.

  • gh-105375: Improve error handling in PyUnicode_BuildEncodingMap() where an exception could end up being overwritten.

  • gh-105235: Prevent out-of-bounds memory access during mmap.find() calls.

  • gh-101006: Improve error handling when read marshal data.

Library

  • gh-105736: Harmonized the pure Python version of OrderedDict with the C version. Now, both versions set up their internal state in __new__. Formerly, the pure Python version did the set up in __init__.

  • gh-107963: Fix multiprocessing.set_forkserver_preload() to check the given list of modules names. Patch by Donghee Na.

  • gh-106242: Fixes os.path.normpath() to handle embedded null characters without truncating the path.

  • gh-107845: tarfile.data_filter() now takes the location of symlinks into account when determining their target, so it will no longer reject some valid tarballs with LinkOutsideDestinationError.

  • gh-107715: Fix doctest.DocTestFinder.find() in presence of class names with special characters. Patch by Gertjan van Zwieten.

  • gh-100814: Passing a callable object as an option value to a Tkinter image now raises the expected TclError instead of an AttributeError.

  • gh-106684: Close asyncio.StreamWriter when it is not closed by application leading to memory leaks. Patch by Kumar Aditya.

  • gh-107077: Seems that in some conditions, OpenSSL will return SSL_ERROR_SYSCALL instead of SSL_ERROR_SSL when a certification verification has failed, but the error parameters will still contain ERR_LIB_SSL and SSL_R_CERTIFICATE_VERIFY_FAILED. We are now detecting this situation and raising the appropiate ssl.SSLCertVerificationError. Patch by Pablo Galindo

  • gh-107396: tarfiles; Fixed use before assignment of self.exception for gzip decompression

  • gh-62519: Make gettext.pgettext() search plural definitions when translation is not found.

  • gh-83006: Document behavior of shutil.disk_usage() for non-mounted filesystems on Unix.

  • gh-106186: Do not report MultipartInvariantViolationDefect defect when the email.parser.Parser class is used to parse emails with headersonly=True.

  • gh-106831: Fix potential missing NULL check of d2i_SSL_SESSION result in _ssl.c.

  • gh-106774: Update the bundled copy of pip to version 23.2.1.

  • gh-106752: Fixed several bug in zipfile.Path in name/suffix/suffixes/stem operations when no filename is present and the Path is not at the root of the zipfile.

  • gh-106602: Add __copy__ and __deepcopy__ in enum

  • gh-106530: Revert a change to colorsys.rgb_to_hls() that caused division by zero for certain almost-white inputs. Patch by Terry Jan Reedy.

  • gh-106052: re module: fix the matching of possessive quantifiers in the case of a subpattern containing backtracking.

  • gh-106510: Improve debug output for atomic groups in regular expressions.

  • gh-105497: Fix flag mask inversion when unnamed flags exist.

  • gh-90876: Prevent multiprocessing.spawn from failing to import in environments where sys.executable is None. This regressed in 3.11 with the addition of support for path-like objects in multiprocessing.

  • gh-106350: Detect possible memory allocation failure in the libtommath function mp_init() used by the _tkinter module.

  • gh-102541: Make pydoc.doc catch bad module ImportError when output stream is not None.

  • gh-106263: Fix crash when calling repr with a manually constructed SignalDict object. Patch by Charlie Zhao.

  • gh-105375: Fix a bug in _Unpickler_SetInputStream() where an exception could end up being overwritten in case of failure.

  • gh-105375: Fix bugs in sys where exceptions could end up being overwritten because of deferred error handling.

  • gh-105605: Harden pyexpat error handling during module initialisation to prevent exceptions from possibly being overwritten, and objects from being dereferenced twice.

  • gh-105375: Fix bug in decimal where an exception could end up being overwritten.

  • gh-105375: Fix bugs in _datetime where exceptions could be overwritten in case of module initialisation failure.

  • gh-105375: Fix bugs in _ssl initialisation which could lead to leaked references and overwritten exceptions.

  • gh-105375: Fix a bug in array.array where an exception could end up being overwritten.

  • gh-105375: Fix bugs in _ctypes where exceptions could end up being overwritten.

  • gh-105375: Fix a bug in the posix module where an exception could be overwritten.

  • gh-105375: Fix bugs in _elementtree where exceptions could be overwritten.

  • gh-105375: Fix bugs in zoneinfo where exceptions could be overwritten.

  • gh-105375: Fix bugs in errno where exceptions could be overwritten.

  • gh-105497: Fix flag inversion when alias/mask members exist.

  • gh-105375: Fix bugs in pickle where exceptions could be overwritten.

  • gh-103171: Revert undocumented behaviour change with runtime-checkable protocols decorated with typing.final() in Python 3.11. The behaviour change had meant that objects would not be considered instances of these protocols at runtime unless they had a __final__ attribute. Patch by Alex Waygood.

  • gh-105375: Fix a bug in sqlite3 where an exception could be overwritten in the collation callback.

  • gh-105332: Revert pickling method from by-name back to by-value.

  • gh-104554: Add RTSPS scheme support in urllib.parse

  • gh-100061: Fix a bug that causes wrong matches for regular expressions with possessive qualifier.

  • gh-102541: Hide traceback in help() prompt, when import failed.

  • gh-99203: Restore following CPython <= 3.10.5 behavior of shutil.make_archive(): do not create an empty archive if root_dir is not a directory, and, in that case, raise FileNotFoundError or NotADirectoryError regardless of format choice. Beyond the brought-back behavior, the function may now also raise these exceptions in dry_run mode.

  • gh-94777: Fix hanging multiprocessing ProcessPoolExecutor when a child process crashes while data is being written in the call queue.

  • bpo-18319: Ensure gettext(msg) retrieve translations even if a plural form exists. In other words: gettext(msg) == ngettext(msg, '', 1).

Documentation

Tests

  • gh-105776: Fix test_cppext when the C compiler command -std=c11 option: remove -std= options from the compiler command. Patch by Victor Stinner.

  • gh-107237: test_logging: Fix test_udp_reconnection() by increasing the timeout from 100 ms to 5 minutes (LONG_TIMEOUT). Patch by Victor Stinner.

  • gh-101634: When running the Python test suite with -jN option, if a worker stdout cannot be decoded from the locale encoding report a failed testn so the exitcode is non-zero. Patch by Victor Stinner.

Build

  • gh-107814: When calling find_python.bat with -q it did not properly silence the output of nuget. That is now fixed.

  • gh-106881: Check for linux/limits.h before including it in Modules/posixmodule.c.

  • gh-104692: Include commoninstall as a prerequisite for bininstall

    This ensures that commoninstall is completed before bininstall is started when parallel builds are used (make -j install), and so the python3 symlink is only installed after all standard library modules are installed.

  • gh-100340: Allows -Wno-int-conversion for wasm-sdk 17 and onwards, thus enables building WASI builds once against the latest sdk.

Windows

  • gh-106242: Fixes realpath() to behave consistently when passed a path containing an embedded null character on Windows. In strict mode, it now raises OSError instead of the unexpected ValueError, and in non-strict mode will make the path absolute.

  • gh-106844: Fix integer overflow in _winapi.LCMapStringEx() which affects ntpath.normcase().

  • gh-99079: Update Windows build to use OpenSSL 3.0.9

  • gh-105436: Ensure that an empty environment block is terminated by two null characters, as is required by Windows.

macOS

  • gh-107565: Update macOS installer to use OpenSSL 3.0.10.

  • gh-99079: Update macOS installer to use OpenSSL 3.0.9.

Tools/Demos

  • gh-107565: Update multissltests and GitHub CI workflows to use OpenSSL 1.1.1v, 3.0.10, and 3.1.2.

  • gh-95065: Argument Clinic now supports overriding automatically generated signature by using directive @text_signature. See the Argument Clinic docs.

  • gh-106970: Fix bugs in the Argument Clinic destination <name> clear command; the destination buffers would never be cleared, and the destination directive parser would simply continue to the fault handler after processing the command. Patch by Erlend E. Aasland.

C API

Python 3.11.4 final

Release date: 2023-06-06

Security

  • gh-103142: The version of OpenSSL used in our binary builds has been upgraded to 1.1.1u to address several CVEs.

  • gh-99889: Fixed a security in flaw in uu.decode() that could allow for directory traversal based on the input if no out_file was specified.

  • gh-104049: Do not expose the local on-disk location in directory indexes produced by http.client.SimpleHTTPRequestHandler.

  • gh-102153: urllib.parse.urlsplit() now strips leading C0 control and space characters following the specification for URLs defined by WHATWG in response to CVE-2023-24329. Patch by Illia Volochii.

Core and Builtins

  • gh-105164: Ensure annotations are set up correctly if the only annotation in a block is within a match block. Patch by Jelle Zijlstra.

  • gh-104615: Fix wrong ordering of assignments in code like a, a = x, y. Contributed by Carl Meyer.

  • gh-104482: Fix three error handling bugs in ast.c’s validation of pattern matching statements.

  • gh-102818: Do not add a frame to the traceback in the sys.setprofile and sys.settrace trampoline functions. This ensures that frames are not duplicated if an exception is raised in the callback function, and ensures that frames are not omitted if a C callback is used and that does not add the frame.

  • gh-104405: Fix an issue where some bytecode instructions could ignore PEP 523 when “inlining” calls.

  • gh-104018: Disallow the “z” format specifier in %-format of bytes objects.

  • gh-103971: Fix an issue where incorrect locations numbers could be assigned to code following case blocks.

  • gh-102310: Change the error range for invalid bytes literals.

  • gh-103590: Do not wrap a single exception raised from a try-except* construct in an ExceptionGroup.

  • gh-101517: Fix bug in line numbers of instructions emitted for except*.

  • gh-103242: Migrate set_ecdh_curve() method not to use deprecated OpenSSL APIs. Patch by Donghee Na.

  • gh-102700: Allow built-in modules to be submodules. This allows submodules to be statically linked into a CPython binary.

  • gh-101857: Fix xattr support detection on Linux systems by widening the check to linux, not just glibc. This fixes support for musl.

  • gh-99184: Bypass instance attribute access of __name__ in repr of weakref.ref.

  • gh-96670: The parser now raises SyntaxError when parsing source code containing null bytes. Backported from aab01e3. Patch by Pablo Galindo

  • bpo-31821: Fix pause_reading() to work when called from connection_made() in asyncio.

Library

  • gh-105080: Fixed inconsistent signature on derived classes for inspect.signature()

  • gh-104874: Document the __name__ and __supertype__ attributes of typing.NewType. Patch by Jelle Zijlstra.

  • gh-104340: When an asyncio pipe protocol loses its connection due to an error, and the caller doesn’t await wait_closed() on the corresponding StreamWriter, don’t log a warning about an exception that was never retrieved. After all, according to the StreamWriter.close() docs, the wait_closed() call is optional (“not mandatory”).

  • gh-104372: Refactored the _posixsubprocess internals to avoid Python C API usage between fork and exec when marking pass_fds= file descriptors inheritable.

  • gh-75367: Fix data descriptor detection in inspect.getattr_static().

  • gh-104536: Fix a race condition in the internal multiprocessing.process cleanup logic that could manifest as an unintended AttributeError when calling process.close().

  • gh-104399: Prepare the _tkinter module for building with Tcl 9.0 and future libtommath by replacing usage of deprecated functions mp_to_unsigned_bin_n() and mp_unsigned_bin_size() when necessary.

  • gh-104307: socket.getnameinfo() now releases the GIL while contacting the DNS server

  • gh-87695: Fix issue where pathlib.Path.glob() raised OSError when it encountered a symlink to an overly long path.

  • gh-104265: Prevent possible crash by disallowing instantiation of the _csv.Reader and _csv.Writer types. The regression was introduced in 3.10.0a4 with PR 23224 (bpo-14935). Patch by Radislav Chugunov.

  • gh-104035: Do not ignore user-defined __getstate__ and __setstate__ methods for slotted frozen dataclasses.

  • gh-103987: In mmap, fix several bugs that could lead to access to memory-mapped files after they have been invalidated.

  • gh-103935: Use io.open_code() for files to be executed instead of raw open()

  • gh-100370: Fix potential OverflowError in sqlite3.Connection.blobopen() for 32-bit builds. Patch by Erlend E. Aasland.

  • gh-103848: Add checks to ensure that [ bracketed ] hosts found by urllib.parse.urlsplit() are of IPv6 or IPvFuture format.

  • gh-103872: Update the bundled copy of pip to version 23.1.2.

  • gh-103861: Fix zipfile.Zipfile creating invalid zip files when force_zip64 was used to add files to them. Patch by Carey Metcalfe.

  • gh-103685: Prepare tkinter.Menu.index() for Tk 8.7 so that it does not raise TclError: expected integer but got "" when it should return None.

  • gh-81403: urllib.request.CacheFTPHandler no longer raises URLError if a cached FTP instance is reused. ftplib’s endtransfer method calls voidresp to drain the connection to handle FTP instance reuse properly.

  • gh-103578: Fixed a bug where pdb crashes when reading source file with different encoding by replacing io.open() with io.open_code(). The new method would also call into the hook set by PyFile_SetOpenCodeHook().

  • gh-103556: Now creating inspect.Signature objects with positional-only parameter with a default followed by a positional-or-keyword parameter without one is impossible.

  • gh-103559: Update the bundled copy of pip to version 23.1.1.

  • gh-103365: Set default Flag boundary to STRICT and fix bitwise operations.

  • gh-103472: Avoid a potential ResourceWarning in http.client.HTTPConnection by closing the proxy / tunnel’s CONNECT response explicitly.

  • gh-103449: Fix a bug in doc string generation in dataclasses.dataclass().

  • gh-103256: Fixed a bug that caused hmac to raise an exception when the requested hash algorithm was not available in OpenSSL despite being available separately as part of hashlib itself. It now falls back properly to the built-in. This could happen when, for example, your OpenSSL does not include SHA3 support and you want to compute hmac.digest(b'K', b'M', 'sha3_256').

  • gh-103225: Fix a bug in pdb when displaying line numbers of module-level source code.

  • gh-93910: Remove deprecation of enum memmber.member access.

  • gh-102978: Fixes unittest.mock.patch() not enforcing function signatures for methods decorated with @classmethod or @staticmethod when patch is called with autospec=True.

  • gh-103204: Fixes http.server accepting HTTP requests with HTTP version numbers preceded by ‘+’, or ‘-’, or with digit-separating ‘_’ characters. The length of the version numbers is also constrained.

  • gh-102953: The extraction methods in tarfile, and shutil.unpack_archive(), have a new a filter argument that allows limiting tar features than may be surprising or dangerous, such as creating files outside the destination directory. See Extraction filters for details.

  • gh-101640: argparse.ArgumentParser now catches errors when writing messages, such as when sys.stderr is None. Patch by Oleg Iarygin.

  • gh-96522: Fix potential deadlock in pty.spawn()

  • gh-87474: Fix potential file descriptor leaks in subprocess.Popen.

Documentation

  • gh-89455: Add missing documentation for the max_group_depth and max_group_width parameters and the exceptions attribute of the traceback.TracebackException class.

  • gh-89412: Add missing documentation for the end_lineno and end_offset attributes of the traceback.TracebackException class.

  • gh-104943: Remove mentions of old Python versions in typing.NamedTuple.

  • gh-67056: Document that the effect of registering or unregistering an atexit cleanup function from within a registered cleanup function is undefined.

  • gh-48241: Clarifying documentation about the url parameter to urllib.request.urlopen and urllib.request.Requst needing to be encoded properly.

Tests

  • gh-104494: Update test_pack_configure_in and test_place_configure_in for changes to error message formatting in Tk 8.7.

  • gh-104461: Run test_configure_screen on X11 only, since the DISPLAY environment variable and -screen option for toplevels are not useful on Tk for Win32 or Aqua.

  • gh-103329: Regression tests for the behaviour of unittest.mock.PropertyMock were added.

  • gh-85984: Utilize new “winsize” functions from termios in pty tests.

  • gh-75729: Fix the os.spawn* tests failing on Windows when the working directory or interpreter path contains spaces.

Build

  • gh-90005: Fix a regression in configure where we could end up unintentionally linking with libbsd.

  • gh-104106: Add gcc fallback of mkfifoat/mknodat for macOS. Patch by Donghee Na.

  • gh-99069: Extended workaround defining static_assert when missing from the libc headers to all clang and gcc builds. In particular, this fixes building on macOS <= 10.10.

Windows

  • gh-105146: Updated the links at the end of the installer to point to Discourse rather than the mailing lists.

  • gh-104623: Update Windows installer to use SQLite 3.42.0.

  • gh-102997: Update Windows installer to use SQLite 3.41.2.

  • gh-88013: Fixed a bug where TypeError was raised when calling ntpath.realpath() with a bytes parameter in some cases.

macOS

  • gh-103142: Update macOS installer to use OpenSSL 1.1.1u.

  • gh-104623: Update macOS installer to SQLite 3.42.0.

  • gh-102997: Update macOS installer to SQLite 3.41.2.

IDLE

  • gh-104719: Remove IDLE’s modification of tokenize.tabsize and test other uses of tokenize data and methods.

  • gh-104499: Fix completions for Tk Aqua 8.7 (currently blank).

  • gh-104496: About prints both tcl and tk versions if different (expected someday).

  • gh-88496: Fix IDLE test hang on macOS.

Python 3.11.3 final

Release date: 2023-04-04

Security

Core and Builtins

  • gh-101975: Fixed stacktop value on tracing entries to avoid corruption on garbage collection.

  • gh-102701: Fix overflow when creating very large dict.

  • gh-102416: Do not memoize incorrectly automatically generated loop rules in the parser. Patch by Pablo Galindo.

  • gh-102356: Fix a bug that caused a crash when deallocating deeply nested filter objects. Patch by Marta Gómez Macías.

  • gh-102397: Fix segfault from race condition in signal handling during garbage collection. Patch by Kumar Aditya.

  • gh-102281: Fix potential nullptr dereference and use of uninitialized memory in fileutils. Patch by Max Bachmann.

  • gh-102126: Fix deadlock at shutdown when clearing thread states if any finalizer tries to acquire the runtime head lock. Patch by Kumar Aditya.

  • gh-102027: Fix SSE2 and SSE3 detection in _blake2 internal module. Patch by Max Bachmann.

  • gh-101967: Fix possible segfault in positional_only_passed_as_keyword function, when new list created.

  • gh-101765: Fix SystemError / segmentation fault in iter __reduce__ when internal access of builtins.__dict__ keys mutates the iter object.

  • gh-101696: Invalidate type version tag in _PyStaticType_Dealloc for static types, avoiding bug where a false cache hit could crash the interpreter. Patch by Kumar Aditya.

Library

  • gh-102549: Don’t ignore exceptions in member type creation.

  • gh-102947: Improve traceback when dataclasses.fields() is called on a non-dataclass. Patch by Alex Waygood

  • gh-102780: The asyncio.Timeout context manager now works reliably even when performing cleanup due to task cancellation. Previously it could raise a CancelledError instead of an TimeoutError in such cases.

  • gh-88965: typing: Fix a bug relating to substitution in custom classes generic over a ParamSpec. Previously, if the ParamSpec was substituted with a parameters list that itself contained a TypeVar, the TypeVar in the parameters list could not be subsequently substituted. This is now fixed.

    Patch by Nikita Sobolev.

  • gh-101979: Fix a bug where parentheses in the metavar argument to argparse.ArgumentParser.add_argument() were dropped. Patch by Yeojin Kim.

  • gh-102179: Fix os.dup2() error message for negative fds.

  • gh-101961: For the binary mode, fileinput.hookcompressed() doesn’t set the encoding value even if the value is None. Patch by Gihwan Kim.

  • gh-101936: The default value of fp becomes io.BytesIO if HTTPError is initialized without a designated fp parameter. Patch by Long Vo.

  • gh-102069: Fix __weakref__ descriptor generation for custom dataclasses.

  • gh-101566: In zipfile, apply fix for extractall on the underlying zipfile after being wrapped in Path.

  • gh-101892: Callable iterators no longer raise SystemError when the callable object exhausts the iterator but forgets to either return a sentinel value or raise StopIteration.

  • gh-97786: Fix potential undefined behaviour in corner cases of floating-point-to-time conversions.

  • gh-101517: Fixed bug where bdb looks up the source line with linecache with a lineno=None, which causes it to fail with an unhandled exception.

  • gh-101673: Fix a pdb bug where ll clears the changes to local variables.

  • gh-96931: Fix incorrect results from ssl.SSLSocket.shared_ciphers()

  • gh-88233: Correctly preserve “extra” fields in zipfile regardless of their ordering relative to a zip64 “extra.”

  • gh-96127: inspect.signature was raising TypeError on call with mock objects. Now it correctly returns (*args, **kwargs) as infered signature.

  • gh-95495: When built against OpenSSL 3.0, the ssl module had a bug where it reported unauthenticated EOFs (i.e. without close_notify) as a clean TLS-level EOF. It now raises SSLEOFError, matching the behavior in previous versions of OpenSSL. The options attribute on SSLContext also no longer includes OP_IGNORE_UNEXPECTED_EOF by default. This option may be set to specify the previous OpenSSL 3.0 behavior.

  • gh-94440: Fix a concurrent.futures.process bug where ProcessPoolExecutor shutdown could hang after a future has been quickly submitted and canceled.

Documentation

Tests

  • gh-102980: Improve test coverage on pdb.

  • gh-102537: Adjust the error handling strategy in test_zoneinfo.TzPathTest.python_tzpath_context. Patch by Paul Ganssle.

  • gh-89792: test_tools now copies up to 10x less source data to a temporary directory during the freeze test by ignoring git metadata and other artifacts. It also limits its python build parallelism based on os.cpu_count instead of hard coding it as 8 cores.

  • gh-101377: Improved test_locale_calendar_formatweekday of calendar.

Build

  • gh-102711: Fix -Wstrict-prototypes compiler warnings.

Windows

  • gh-101849: Ensures installer will correctly upgrade existing py.exe launcher installs.

  • gh-101763: Updates copy of libffi bundled with Windows installs to 3.4.4.

  • gh-101759: Update Windows installer to SQLite 3.40.1.

  • gh-101614: Correctly handle extensions built against debug binaries that reference python3_d.dll.

macOS

  • gh-103207: Add instructions to the macOS installer welcome display on how to workaround the macOS 13 Ventura “The installer encountered an error” failure.

  • gh-101759: Update macOS installer to SQLite 3.40.1.

Python 3.11.2 final

Release date: 2023-02-07

Core and Builtins

  • gh-92173: Fix the defs and kwdefs arguments to PyEval_EvalCodeEx() and a reference leak in that function.

  • gh-101400: Fix wrong lineno in exception message on continue or break which are not in a loop. Patch by Donghee Na.

  • gh-101372: Fix is_normalized() to properly handle the UCD 3.2.0 cases. Patch by Donghee Na.

  • gh-101046: Fix a possible memory leak in the parser when raising MemoryError. Patch by Pablo Galindo

  • gh-101037: Fix potential memory underallocation issue for instances of int subclasses with value zero.

  • gh-100942: Fixed segfault in property.getter/setter/deleter that occurred when a property subclass overrode the __new__ method to return a non-property instance.

  • gh-100892: Fix race while iterating over thread states in clearing threading.local. Patch by Kumar Aditya.

  • gh-100776: Fix misleading default value in input()’s __text_signature__.

  • gh-100637: Fix int.__sizeof__() calculation to include the 1 element ob_digit array for 0 and False.

  • gh-100649: Update the native_thread_id field of PyThreadState after fork.

  • gh-100374: Fix incorrect result and delay in socket.getfqdn(). Patch by Dominic Socular.

  • gh-99110: Initialize frame->previous in frameobject.c to fix a segmentation fault when accessing frames created by PyFrame_New().

  • gh-100050: Honor existing errors obtained when searching for mismatching parentheses in the tokenizer. Patch by Pablo Galindo

  • bpo-32782: ctypes arrays of length 0 now report a correct itemsize when a memoryview is constructed from them, rather than always giving a value of 0.

Library

  • gh-101541: [Enum] - fix psuedo-flag creation

  • gh-101326: Fix regression when passing None as second or third argument to FutureIter.throw.

  • gh-100795: Avoid potential unexpected freeaddrinfo call (double free) in socket when when a libc getaddrinfo() implementation leaves garbage in an output pointer when returning an error. Original patch by Sergey G. Brester.

  • gh-101143: Remove unused references to TimerHandle in asyncio.base_events.BaseEventLoop._add_callback.

  • gh-101144: Make zipfile.Path.open() and zipfile.Path.read_text() also accept encoding as a positional argument. This was the behavior in Python 3.9 and earlier. 3.10 introduced a regression where supplying it as a positional argument would lead to a TypeError.

  • gh-101015: Fix typing.get_type_hints() on '*tuple[...]' and *tuple[...]. It must not drop the Unpack part.

  • gh-100573: Fix a Windows asyncio bug with named pipes where a client doing os.stat() on the pipe would cause an error in the server that disabled serving future requests.

  • gh-100805: Modify random.choice() implementation to once again work with NumPy arrays.

  • gh-90104: Avoid RecursionError on repr if a dataclass field definition has a cyclic reference.

  • gh-100750: pass encoding kwarg to subprocess in platform

  • gh-100689: Fix crash in pyexpat by statically allocating PyExpat_CAPI capsule.

  • gh-100740: Fix unittest.mock.Mock not respecting the spec for attribute names prefixed with assert.

  • gh-86508: Fix asyncio.open_connection() to skip binding to local addresses of different family. Patch by Kumar Aditya.

  • gh-100287: Fix the interaction of unittest.mock.seal() with unittest.mock.AsyncMock.

  • gh-100474: http.server now checks that an index page is actually a regular file before trying to serve it. This avoids issues with directories named index.html.

  • gh-100160: Remove any deprecation warnings in asyncio.get_event_loop(). They are deferred to Python 3.12.

  • gh-96290: Fix handling of partial and invalid UNC drives in ntpath.splitdrive(), and in ntpath.normpath() on non-Windows systems. Paths such as ‘\server’ and ‘\’ are now considered by splitdrive() to contain only a drive, and consequently are not modified by normpath() on non-Windows systems. The behaviour of normpath() on Windows systems is unaffected, as native OS APIs are used. Patch by Eryk Sun, with contributions by Barney Gale.

  • gh-78878: Fix crash when creating an instance of _ctypes.CField.

  • gh-99952: Fix a reference undercounting issue in ctypes.Structure with from_param() results larger than a C pointer.

  • gh-100133: Fix regression in asyncio where a subprocess would sometimes lose data received from pipe.

  • gh-100098: Fix tuple subclasses being cast to tuple when used as enum values.

  • gh-98778: Update HTTPError to be initialized properly, even if the fp is None. Patch by Donghee Na.

  • gh-83035: Fix inspect.getsource() handling of decorator calls with nested parentheses.

  • gh-99576: Fix .save() method for LWPCookieJar and MozillaCookieJar: saved file was not truncated on repeated save.

  • gh-99433: Fix doctest failure on types.MethodWrapperType in modules.

  • gh-99240: Fix double-free bug in Argument Clinic str_converter by extracting memory clean up to a new post_parsing section.

  • gh-64490: Fix refcount error when arguments are packed to tuple in Argument Clinic.

  • gh-85267: Several improvements to inspect.signature()’s handling of __text_signature. - Fixes a case where inspect.signature() dropped parameters - Fixes a case where inspect.signature() raised tokenize.TokenError - Allows inspect.signature() to understand defaults involving binary operations of constants - inspect.signature() is documented as only raising TypeError or ValueError, but sometimes raised RuntimeError. These cases now raise ValueError - Removed a dead code path

  • gh-95882: Fix a 3.11 regression in asynccontextmanager(), which caused it to propagate exceptions with incorrect tracebacks and fix a 3.11 regression in contextmanager(), which caused it to propagate exceptions with incorrect tracebacks for StopIteration.

  • bpo-44817: Ignore WinError 53 (ERROR_BAD_NETPATH), 65 (ERROR_NETWORK_ACCESS_DENIED) and 161 (ERROR_BAD_PATHNAME) when using ntpath.realpath().

  • bpo-40447: Accept os.PathLike (such as pathlib.Path) in the stripdir arguments of compileall.compile_file() and compileall.compile_dir().

  • bpo-36880: Fix a reference counting issue when a ctypes callback with return type py_object returns None, which could cause crashes.

Documentation

Tests

  • gh-101334: test_tarfile has been updated to pass when run as a high UID.

  • gh-100454: Start running SSL tests with OpenSSL 3.1.0-beta1.

  • gh-96002: Add functional test for Argument Clinic.

Build

  • gh-101522: Allow overriding Windows dependencies versions and paths using MSBuild properties.

Windows

  • gh-101543: Ensure the install path in the registry is only used when the standard library hasn’t been located in any other way.

  • gh-101467: The py.exe launcher now correctly filters when only a single runtime is installed. It also correctly handles prefix matches on tags so that -3.1 does not match 3.11, but would still match 3.1-32.

  • gh-101135: Restore ability to launch older 32-bit versions from the py.exe launcher when both 32-bit and 64-bit installs of the same version are available.

  • gh-82052: Fixed an issue where writing more than 32K of Unicode output to the console screen in one go can result in mojibake.

  • gh-100320: Ensures the PythonPath registry key from an install is used when launching from a different copy of Python that relies on an existing install to provide a copy of its modules and standard library.

  • gh-100247: Restores support for the py.exe launcher finding shebang commands in its configuration file using the full command name.

  • gh-100180: Update Windows installer to OpenSSL 1.1.1s

  • bpo-43984: winreg.SetValueEx() now leaves the target value untouched in the case of conversion errors. Previously, -1 would be written in case of such errors.

macOS

  • gh-100180: Update macOS installer to OpenSSL 1.1.1s

Tools/Demos

  • bpo-45256: Fix a bug that caused an AttributeError to be raised in python-gdb.py when py-locals is used without a frame.

  • gh-100342: Add missing NULL check for possible allocation failure in *args parsing in Argument Clinic.

  • gh-64490: Argument Clinic varargs bugfixes

    • Fix out-of-bounds error in _PyArg_UnpackKeywordsWithVararg().

    • Fix incorrect check which allowed more than one varargs in clinic.py.

    • Fix miscalculation of noptargs in generated code.

    • Do not generate noptargs when there is a vararg argument and no optional argument.

C API

  • gh-99240: In argument parsing, after deallocating newly allocated memory, reset its pointer to NULL.

Python 3.11.1 final

Release date: 2022-12-06

Security

  • gh-100001: python -m http.server no longer allows terminal control characters sent within a garbage request to be printed to the stderr server log.

    This is done by changing the http.server BaseHTTPRequestHandler .log_message method to replace control characters with a \xHH hex escape before printing.

  • gh-87604: Avoid publishing list of active per-interpreter audit hooks via the gc module

  • gh-98433: The IDNA codec decoder used on DNS hostnames by socket or asyncio related name resolution functions no longer involves a quadratic algorithm. This prevents a potential CPU denial of service if an out-of-spec excessive length hostname involving bidirectional characters were decoded. Some protocols such as urllib http 3xx redirects potentially allow for an attacker to supply such a name.

  • gh-98739: Update bundled libexpat to 2.5.0

  • gh-97612: Fix a shell code injection vulnerability in the get-remote-certificate.py example script. The script no longer uses a shell to run openssl commands. Issue reported and initial fix by Caleb Shortt. Patch by Victor Stinner.

Core and Builtins

  • gh-99886: Fix a crash when an object which does not have a dictionary frees its instance values.

  • gh-99891: Fix a bug in the tokenizer that could cause infinite recursion when showing syntax warnings that happen in the first line of the source. Patch by Pablo Galindo

  • gh-99729: Fix an issue that could cause frames to be visible to Python code as they are being torn down, possibly leading to memory corruption or hard crashes of the interpreter.

  • gh-99578: Fix a reference bug in _imp.create_builtin() after the creation of the first sub-interpreter for modules builtins and sys. Patch by Victor Stinner.

  • gh-99581: Fixed a bug that was causing a buffer overflow if the tokenizer copies a line missing the newline caracter from a file that is as long as the available tokenizer buffer. Patch by Pablo galindo

  • gh-99553: Fix bug where an ExceptionGroup subclass can wrap a BaseException.

  • gh-99370: Fix zip path for venv created from a non-installed python on POSIX platforms.

  • gh-99298: Fix an issue that could potentially cause incorrect error handling for some bytecode instructions.

  • gh-99205: Fix an issue that prevented PyThreadState and PyInterpreterState memory from being freed properly.

  • gh-99181: Fix failure in except* with unhashable exceptions.

  • gh-99204: Fix calculation of sys._base_executable when inside a POSIX virtual environment using copies of the python binary when the base installation does not provide the executable name used by the venv. Calculation will fall back to alternative names (“python<MAJOR>”, “python<MAJOR>.<MINOR>”).

  • gh-96055: Update faulthandler to emit an error message with the proper unexpected signal number. Patch by Donghee Na.

  • gh-99153: Fix location of SyntaxError for a try block with both except and except*.

  • gh-99103: Fix the error reporting positions of specialized traceback anchors when the source line contains Unicode characters.

  • gh-98852: Fix subscription of type aliases containing bare generic types or types like TypeVar: for example tuple[A, T][int] and tuple[TypeVar, T][int], where A is a generic type, and T is a type variable.

  • gh-98925: Lower the recursion depth for marshal on WASI to support wasmtime 2.0/main.

  • gh-98783: Fix multiple crashes in debug mode when str subclasses are used instead of str itself.

  • gh-99257: Fix an issue where member descriptors (such as those for __slots__) could behave incorrectly or crash instead of raising a TypeError when accessed via an instance of an invalid type.

  • gh-98374: Suppress ImportError for invalid query for help() command. Patch by Donghee Na.

  • gh-98415: Fix detection of MAC addresses for uuid on certain OSs. Patch by Chaim Sanders

  • gh-92119: Print exception class name instead of its string representation when raising errors from ctypes calls.

  • gh-96078: os.sched_yield() now release the GIL while calling sched_yield(2). Patch by Donghee Na.

  • gh-93354: Fix an issue that could delay the specialization of PRECALL instructions.

  • gh-97943: Bugfix: PyFunction_GetAnnotations() should return a borrowed reference. It was returning a new reference.

  • gh-97779: Ensure that all Python frame objects are backed by “complete” frames.

  • gh-97591: Fixed a missing incref/decref pair in Exception.__setstate__(). Patch by Ofey Chan.

  • gh-94526: Fix the Python path configuration used to initialized sys.path at Python startup. Paths are no longer encoded to UTF-8/strict to avoid encoding errors if it contains surrogate characters (bytes paths are decoded with the surrogateescape error handler). Patch by Victor Stinner.

  • gh-95921: Fix overly-broad source position information for chained comparisons used as branching conditions.

  • gh-96387: At Python exit, sometimes a thread holding the GIL can wait forever for a thread (usually a daemon thread) which requested to drop the GIL, whereas the thread already exited. To fix the race condition, the thread which requested the GIL drop now resets its request before exiting. Issue discovered and analyzed by Mingliang ZHAO. Patch by Victor Stinner.

  • gh-96864: Fix a possible assertion failure, fatal error, or SystemError if a line tracing event raises an exception while opcode tracing is enabled.

  • gh-96678: Fix undefined behaviour in C code of null pointer arithmetic.

  • gh-96754: Make sure that all frame objects created are created from valid interpreter frames. Prevents the possibility of invalid frames in backtraces and signal handlers.

  • gh-95196: Disable incorrect pickling of the C implemented classmethod descriptors.

  • gh-96005: On WASI ENOTCAPABLE is now mapped to PermissionError. The errno modules exposes the new error number. getpath.py now ignores PermissionError when it cannot open landmark files pybuilddir.txt and pyenv.cfg.

  • gh-93696: Allow pdb to locate source for frozen modules in the standard library.

  • bpo-31718: Raise ValueError instead of SystemError when methods of uninitialized io.IncrementalNewlineDecoder objects are called. Patch by Oren Milman.

  • bpo-38031: Fix a possible assertion failure in io.FileIO when the opener returns an invalid file descriptor.

Library

  • gh-100001: Also escape s in the http.server BaseHTTPRequestHandler.log_message so that it is technically possible to parse the line and reconstruct what the original data was. Without this a xHH is ambiguious as to if it is a hex replacement we put in or the characters r”x” came through in the original request line.

  • gh-93453: asyncio.get_event_loop() now only emits a deprecation warning when a new event loop was created implicitly. It no longer emits a deprecation warning if the current event loop was set.

  • gh-51524: Fix bug when calling trace.CoverageResults with valid infile.

  • gh-99645: Fix a bug in handling class cleanups in unittest.TestCase. Now addClassCleanup() uses separate lists for different TestCase subclasses, and doClassCleanups() only cleans up the particular class.

  • gh-97001: Release the GIL when calling termios APIs to avoid blocking threads.

  • gh-99341: Fix ast.increment_lineno() to also cover ast.TypeIgnore when changing line numbers.

  • gh-99418: Fix bug in urllib.parse.urlparse() that causes URL schemes that begin with a digit, a plus sign, or a minus sign to be parsed incorrectly.

  • gh-99382: Check the number of arguments in substitution in user generics containing a TypeVarTuple and one or more TypeVar.

  • gh-99379: Fix substitution of ParamSpec followed by TypeVarTuple in generic aliases.

  • gh-99344: Fix substitution of TypeVarTuple and ParamSpec together in user generics.

  • gh-74044: Fixed bug where inspect.signature() reported incorrect arguments for decorated methods.

  • gh-99275: Fix SystemError in ctypes when exception was not set during __initsubclass__.

  • gh-99277: Remove older version of _SSLProtocolTransport.get_write_buffer_limits in asyncio.sslproto

  • gh-99248: fix negative numbers failing in verify()

  • gh-99155: Fix statistics.NormalDist pickle with 0 and 1 protocols.

  • gh-93464: enum.auto() is now correctly activated when combined with other assignment values. E.g. ONE = auto(), 'some text' will now evaluate as (1, 'some text').

  • gh-99134: Update the bundled copy of pip to version 22.3.1.

  • gh-83004: Clean up refleak on failed module initialisation in _zoneinfo

  • gh-83004: Clean up refleaks on failed module initialisation in in _pickle

  • gh-83004: Clean up refleak on failed module initialisation in _io.

  • gh-98897: Fix memory leak in math.dist() when both points don’t have the same dimension. Patch by Kumar Aditya.

  • gh-98706: [3.11] Applied changes from importlib_metadata 4.11.4 through 4.13, including compatibility and robustness fixes for Distribution objects without _normalized_name, disallowing invalid inputs to Distribution.from_name, and refined behaviors in PathDistribution._name_from_stem and PathDistribution._normalized_name.

  • gh-98793: Fix argument typechecks in _overlapped.WSAConnect() and _overlapped.Overlapped.WSASendTo() functions.

  • gh-98744: Prevent crashing in traceback when retrieving the byte-offset for some source files that contain certain unicode characters.

  • gh-98740: Fix internal error in the re module which in very rare circumstances prevented compilation of a regular expression containing a conditional expression without the “else” branch.

  • gh-98703: Fix asyncio.StreamWriter.drain() to call protocol.connection_lost callback only once on Windows.

  • gh-98624: Add a mutex to unittest.mock.NonCallableMock to protect concurrent access to mock attributes.

  • gh-89237: Fix hang on Windows in subprocess.wait_closed() in asyncio with ProactorEventLoop. Patch by Kumar Aditya.

  • gh-98458: Fix infinite loop in unittest when a self-referencing chained exception is raised

  • gh-97928: tkinter.Text.count() raises now an exception for options starting with “-” instead of silently ignoring them.

  • gh-97966: On uname_result, restored expectation that _fields and _asdict would include all six properties including processor.

  • gh-98307: A createSocket() method was added to SysLogHandler.

  • gh-96035: Fix bug in urllib.parse.urlparse() that causes certain port numbers containing whitespace, underscores, plus and minus signs, or non-ASCII digits to be incorrectly accepted.

  • gh-98251: Allow venv to pass along PYTHON* variables to ensurepip and pip when they do not impact path resolution

  • gh-98178: On macOS, fix a crash in syslog.syslog() in multi-threaded applications. On macOS, the libc syslog() function is not thread-safe, so syslog.syslog() no longer releases the GIL to call it. Patch by Victor Stinner.

  • gh-96151: Allow BUILTINS to be a valid field name for frozen dataclasses.

  • gh-87730: Wrap network errors consistently in urllib FTP support, so the test suite doesn’t fail when a network is available but the public internet is not reachable.

  • gh-98086: Make sure patch.dict() can be applied on async functions.

  • gh-90985: Earlier in 3.11 we deprecated asyncio.Task.cancel("message"). We realized we were too harsh, and have undeprecated it.

  • gh-97837: Change deprecate warning message in unittest from

    It is deprecated to return a value!=None

    to

    It is deprecated to return a value that is not None from a test case

  • gh-97825: Fixes AttributeError when subprocess.check_output() is used with argument input=None and either of the arguments encoding or errors are used.

  • gh-82836: Fix is_private properties in the ipaddress module. Previously non-private networks (0.0.0.0/0) would return True from this method; now they correctly return False.

  • gh-96827: Avoid spurious tracebacks from asyncio when default executor cleanup is delayed until after the event loop is closed (e.g. as the result of a keyboard interrupt).

  • gh-97592: Avoid a crash in the C version of asyncio.Future.remove_done_callback() when an evil argument is passed.

  • gh-97639: Remove tokenize.NL check from tabnanny.

  • gh-73588: Fix generation of the default name of tkinter.Checkbutton. Previously, checkbuttons in different parent widgets could have the same short name and share the same state if arguments “name” and “variable” are not specified. Now they are globally unique.

  • gh-97005: Update bundled libexpat to 2.4.9

  • gh-85760: Fix race condition in asyncio where process_exited() called before the pipe_data_received() leading to inconsistent output. Patch by Kumar Aditya.

  • gh-96819: Fixed check in multiprocessing.resource_tracker that guarantees that the length of a write to a pipe is not greater than PIPE_BUF.

  • gh-96741: Corrected type annotation for dataclass attribute pstats.FunctionProfile.ncalls to be str.

  • gh-95987: Fix repr of Any subclasses.

  • gh-96388: Work around missing socket functions in socket’s __repr__.

  • gh-96073: In inspect, fix overeager replacement of “typing.” in formatting annotations.

  • gh-96192: Fix handling of bytes path-like objects in os.ismount().

  • gh-96052: Fix handling compiler warnings (SyntaxWarning and DeprecationWarning) in codeop.compile_command() when checking for incomplete input. Previously it emitted warnings and raised a SyntaxError. Now it always returns None for incomplete input without emitting any warnings.

  • gh-88863: To avoid apparent memory leaks when asyncio.open_connection() raises, break reference cycles generated by local exception and future instances (which has exception instance as its member var). Patch by Dong Uk, Kang.

  • gh-91212: Fixed flickering of the turtle window when the tracer is turned off. Patch by Shin-myoung-serp.

  • gh-88050: Fix asyncio subprocess transport to kill process cleanly when process is blocked and avoid RuntimeError when loop is closed. Patch by Kumar Aditya.

  • gh-93858: Prevent error when activating venv in nested fish instances.

  • gh-91078: TarFile.next() now returns None when called on an empty tarfile.

  • bpo-47220: Document the optional callback parameter of WeakMethod. Patch by Géry Ogam.

  • bpo-46364: Restrict use of sockets instead of pipes for stdin of subprocesses created by asyncio to AIX platform only.

  • bpo-38523: shutil.copytree() now applies the ignore_dangling_symlinks argument recursively.

  • bpo-36267: Fix IndexError in argparse.ArgumentParser when a store_true action is given an explicit argument.

Documentation

  • gh-92892: Document that calling variadic functions with ctypes requires special care on macOS/arm64 (and possibly other platforms).

  • gh-85525: Remove extra row

  • gh-95588: Clarified the conflicting advice given in the ast documentation about ast.literal_eval() being “safe” for use on untrusted input while at the same time warning that it can crash the process. The latter statement is true and is deemed unfixable without a large amount of work unsuitable for a bugfix. So we keep the warning and no longer claim that literal_eval is safe.

  • bpo-41825: Restructured the documentation for the os.wait* family of functions, and improved the docs for os.waitid() with more explanation of the possible argument constants.

Tests

  • gh-99892: Skip test_normalization() of test_unicodedata if it fails to download NormalizationTest.txt file from pythontest.net. Patch by Victor Stinner.

  • gh-99934: Correct test_marsh on (32 bit) x86: test_deterministic sets was failing.

  • gh-99659: Optional big memory tests in test_sqlite3 now catch the correct sqlite.DataError exception type in case of too large strings and/or blobs passed.

  • gh-98713: Fix a bug in the typing tests where a test relying on CPython-specific implementation details was not decorated with @cpython_only and was not skipped on other implementations.

  • gh-87390: Add tests for star-unpacking with PEP 646, and some other miscellaneous PEP 646 tests.

  • gh-96853: Added explicit coverage of Py_Initialize (and hence Py_InitializeEx) back to the embedding tests (all other embedding tests migrated to Py_InitializeFromConfig in Python 3.11)

  • bpo-34272: Some C API tests were moved into the new Lib/test/test_capi/ directory.

Build

  • gh-99086: Fix -Wimplicit-int, -Wstrict-prototypes, and -Wimplicit-function-declaration compiler warnings in configure checks.

  • gh-99337: Fix a compilation issue with GCC 12 on macOS.

  • gh-99086: Fix -Wimplicit-int compiler warning in configure check for PTHREAD_SCOPE_SYSTEM.

  • gh-98872: Fix a possible fd leak in Programs/_freeze_module.c introduced in Python 3.11.

  • gh-99016: Fix build with PYTHON_FOR_REGEN=python3.8.

  • gh-97731: Specify the full path to the source location for make docclean (needed for cross-builds).

  • gh-98707: Don’t use vendored libmpdec headers if --with-system-libmpdec is passed to configure. Don’t use vendored libexpat headers if --with-system-expat is passed to !configure.

  • gh-96761: Fix the build process of clang compiler for _bootstrap_python if LTO optimization is applied. Patch by Matthias Görgens and Donghee Na.

  • gh-96883: wasm32-emscripten builds for browsers now include concurrent.futures for asyncio and unittest.mock.

  • gh-84461: wasm32-emscripten platform no longer builds resource module, getresuid(), getresgid(), and their setters. The APIs are stubs and not functional.

  • gh-94280: Updated pegen regeneration script on Windows to find and use Python 3.9 or higher. Prior to this, pegen regeneration already required 3.9 or higher, but the script may have used lower versions of Python.

Windows

  • gh-99345: Use faster initialization functions to detect install location for Windows Store package

  • gh-98629: Fix initialization of sys.version and sys._git on Windows

  • gh-99442: Fix handling in Python Launcher for Windows when argv[0] does not include a file extension.

  • gh-98689: Update Windows builds to zlib v1.2.13. v1.2.12 has CVE-2022-37434, but the vulnerable inflateGetHeader API is not used by Python.

  • gh-98790: Assumes that a missing DLLs directory means that standard extension modules are in the executable’s directory.

  • gh-98745: Update py.exe launcher to install 3.11 by default and 3.12 on request.

  • gh-98692: Fix the Python Launcher for Windows ignoring unrecognized shebang lines instead of treating them as local paths

  • gh-94328: Update Windows installer to use SQLite 3.39.4.

  • gh-97728: Fix possible crashes caused by the use of uninitialized variables when pass invalid arguments in os.system() on Windows and in Windows-specific modules (like winreg).

  • gh-96965: Update libffi to 3.4.3

  • gh-94781: Fix pcbuild.proj to clean previous instances of ouput files in Python\deepfreeze and Python\frozen_modules directories on Windows. Patch by Charlie Zhao.

  • bpo-40882: Fix a memory leak in multiprocessing.shared_memory.SharedMemory on Windows.

macOS

  • gh-87235: On macOS python3 /dev/fd/9 9</path/to/script.py failed for any script longer than a couple of bytes.

  • gh-98940: Fix Mac/Extras.install.py file filter bug.

  • gh-94328: Update macOS installer to SQLite 3.39.4.

IDLE

  • gh-97527: Fix a bug in the previous bugfix that caused IDLE to not start when run with 3.10.8, 3.12.0a1, and at least Microsoft Python 3.10.2288.0 installed without the Lib/test package. 3.11.0 was never affected.

Tools/Demos

  • gh-95853: The wasm_build.py script now pre-builds Emscripten ports, checks for broken EMSDK versions, and warns about pkg-config env vars.

  • gh-95853: The new tool Tools/wasm/wasm_builder.py automates configure, compile, and test steps for building CPython on WebAssembly platforms.

  • gh-95731: Fix handling of module docstrings in Tools/i18n/pygettext.py.

C API

  • gh-98680: PyBUF_* constants were marked as part of Limited API of Python 3.11+. These were available in 3.11.0 with Py_LIMITED_API defined for 3.11, and are necessary to use the buffer API.

  • gh-98978: Fix use-after-free in Py_SetPythonHome(NULL), Py_SetProgramName(NULL) and _Py_SetProgramFullPath(NULL) function calls. Issue reported by Benedikt Reinartz. Patch by Victor Stinner.

  • gh-96853: Py_InitializeEx now correctly calls PyConfig_Clear after initializing the interpreter (the omission didn’t cause a memory leak only because none of the dynamically allocated config fields are populated by the wrapper function)

Python 3.11.0 final

Release date: 2022-10-24

Security

  • gh-97616: Fix multiplying a list by an integer (list *= int): detect the integer overflow when the new allocated length is close to the maximum size. Issue reported by Jordan Limor. Patch by Victor Stinner.

  • gh-97514: On Linux the multiprocessing module returns to using filesystem backed unix domain sockets for communication with the forkserver process instead of the Linux abstract socket namespace. Only code that chooses to use the “forkserver” start method is affected.

    Abstract sockets have no permissions and could allow any user on the system in the same network namespace (often the whole system) to inject code into the multiprocessing forkserver process. This was a potential privilege escalation. Filesystem based socket permissions restrict this to the forkserver process user as was the default in Python 3.8 and earlier.

    This prevents Linux CVE-2022-42919.

Core and Builtins

  • gh-97002: Fix an issue where several frame objects could be backed by the same interpreter frame, possibly leading to corrupted memory and hard crashes of the interpreter.

  • gh-97752: Fix possible data corruption or crashes when accessing the f_back member of newly-created generator or coroutine frames.

  • gh-96975: Fix a crash occurring when PyEval_GetFrame() is called while the topmost Python frame is in a partially-initialized state.

  • gh-96848: Fix command line parsing: reject -X int_max_str_digits option with no value (invalid) when the PYTHONINTMAXSTRDIGITS environment variable is set to a valid limit. Patch by Victor Stinner.

  • gh-96821: Fix undefined behaviour in _testcapimodule.c.

  • gh-95778: When ValueError is raised if an integer is larger than the limit, mention the sys.set_int_max_str_digits() function in the error message. Patch by Victor Stinner.

  • gh-96587: Correctly raise SyntaxError on exception groups (PEP 654) on python versions prior to 3.11

  • bpo-42316: Document some places where an assignment expression needs parentheses.

Library

  • gh-98331: Update the bundled copies of pip and setuptools to versions 22.3 and 65.5.0 respectively.

  • gh-90985: Earlier in 3.11 we deprecated asyncio.Task.cancel("message"). We realized we were too harsh, and have undeprecated it.

  • gh-97545: Make Semaphore run faster.

  • gh-96865: fix Flag to use boundary CONFORM

    This restores previous Flag behavior of allowing flags with non-sequential values to be combined; e.g.

    class Skip(Flag): TWO = 2 EIGHT = 8

    Skip.TWO | Skip.EIGHT -> <Skip.TWO|EIGHT: 10>

  • gh-90155: Fix broken asyncio.Semaphore when acquire is cancelled.

Documentation

  • gh-97741: Fix ! in c domain ref target syntax via a conf.py patch, so it works as intended to disable ref target resolution.

  • gh-93031: Update tutorial introduction output to use 3.10+ SyntaxError invalid range.

Tests

  • gh-95027: On Windows, when the Python test suite is run with the -jN option, the ANSI code page is now used as the encoding for the stdout temporary file, rather than using UTF-8 which can lead to decoding errors. Patch by Victor Stinner.

Build

  • gh-96729: Ensure that Windows releases built with Tools\msi\buildrelease.bat are upgradable to and from official Python releases.

Windows

  • gh-98360: Fixes multiprocessing spawning child processes on Windows from a virtual environment to ensure that child processes that also use multiprocessing to spawn more children will recognize that they are in a virtual environment.

  • gh-98414: Fix py.exe launcher handling of -V:<company>/ option when default preferences have been set in environment variables or configuration files.

  • gh-90989: Clarify some text in the Windows installer.

macOS

  • gh-97897: The macOS 13 SDK includes support for the mkfifoat and mknodat system calls. Using the dir_fd option with either os.mkfifo() or os.mknod() could result in a segfault if cpython is built with the macOS 13 SDK but run on an earlier version of macOS. Prevent this by adding runtime support for detection of these system calls (“weaklinking”) as is done for other newer syscalls on macOS.

Python 3.11.0 release candidate 2

Release date: 2022-09-11

Security

  • gh-95778: Converting between int and str in bases other than 2 (binary), 4, 8 (octal), 16 (hexadecimal), or 32 such as base 10 (decimal) now raises a ValueError if the number of digits in string form is above a limit to avoid potential denial of service attacks due to the algorithmic complexity. This is a mitigation for CVE-2020-10735.

    This new limit can be configured or disabled by environment variable, command line flag, or sys APIs. See the integer string conversion length limitation documentation. The default limit is 4300 digits in string form.

    Patch by Gregory P. Smith [Google] and Christian Heimes [Red Hat] with feedback from Victor Stinner, Thomas Wouters, Steve Dower, Ned Deily, and Mark Dickinson.

Core and Builtins

  • gh-96678: Fix case of undefined behavior in ceval.c

  • gh-96641: Do not expose KeyWrapper in _functools.

  • gh-96636: Ensure that tracing, sys.setrace(), is turned on immediately. In pre-release versions of 3.11, some tracing events might have been lost when turning on tracing in a __del__ method or interrupt.

  • gh-96572: Fix use after free in trace refs build mode. Patch by Kumar Aditya.

  • gh-96611: When loading a file with invalid UTF-8 inside a multi-line string, a correct SyntaxError is emitted.

  • gh-96612: Make sure that incomplete frames do not show up in tracemalloc traces.

  • gh-96569: Remove two cases of undefined behavior, by adding NULL checks.

  • gh-96582: Fix possible NULL pointer dereference in _PyThread_CurrentFrames. Patch by Kumar Aditya.

  • gh-96352: Fix AttributeError missing name and obj attributes in object.__getattribute__(). Patch by Philip Georgi.

  • gh-96268: Loading a file with invalid UTF-8 will now report the broken character at the correct location.

  • gh-96187: Fixed a bug that caused _PyCode_GetExtra to return garbage for negative indexes. Patch by Pablo Galindo

  • gh-96071: Fix a deadlock in PyGILState_Ensure() when allocating new thread state. Patch by Kumar Aditya.

  • gh-96046: PyType_Ready() now initializes ht_cached_keys and performs additional checks to ensure that type objects are properly configured. This avoids crashes in 3rd party packages that don’t use regular API to create new types.

  • gh-95818: Skip over incomplete frames in PyThreadState_GetFrame().

  • gh-95876: Fix format string in _PyPegen_raise_error_known_location that can lead to memory corruption on some 64bit systems. The function was building a tuple with i (int) instead of n (Py_ssize_t) for Py_ssize_t arguments.

  • gh-95605: Fix misleading contents of error message when converting an all-whitespace string to float.

  • gh-94996: ast.parse() will no longer parse function definitions with positional-only params when passed feature_version less than (3, 8). Patch by Shantanu Jain.

Library

  • gh-96700: Fix incorrect error message in the io module.

  • gh-96652: Fix the faulthandler implementation of faulthandler.register(signal, chain=True) if the sigaction() function is not available: don’t call the previous signal handler if it’s NULL. Patch by Victor Stinner.

  • gh-68163: Correct conversion of numbers.Rational’s to float.

  • gh-96385: Fix TypeVarTuple.__typing_prepare_subst__. TypeError was not raised when using more than one TypeVarTuple, like [*T, *V] in type alias substitutions.

  • gh-90467: Fix asyncio.streams.StreamReaderProtocol to keep a strong reference to the created task, so that it’s not garbage collected

  • gh-96159: Fix a performance regression in logging TimedRotatingFileHandler. Only check for special files when the rollover time has passed.

  • gh-96175: Fix unused localName parameter in the Attr class in xml.dom.minidom.

  • gh-96125: Fix incorrect condition that causes sys.thread_info.name to be wrong on pthread platforms.

  • gh-95463: Remove an incompatible change from bpo-28080 that caused a regression that ignored the utf8 in ZipInfo.flag_bits. Patch by Pablo Galindo.

  • gh-95899: Fix asyncio.Runner to call asyncio.set_event_loop() only once to avoid calling attach_loop() multiple times on child watchers. Patch by Kumar Aditya.

  • gh-95736: Fix unittest.IsolatedAsyncioTestCase to set event loop before calling setup functions. Patch by Kumar Aditya.

  • gh-95704: When a task catches asyncio.CancelledError and raises some other error, the other error should generally not silently be suppressed.

  • gh-95231: Fail gracefully if EPERM or ENOSYS is raised when loading crypt methods. This may happen when trying to load MD5 on a Linux kernel with FIPS enabled.

  • gh-74116: Allow asyncio.StreamWriter.drain() to be awaited concurrently by multiple tasks. Patch by Kumar Aditya.

  • gh-92986: Fix ast.unparse() when ImportFrom.level is None

Documentation

  • gh-96098: Improve discoverability of the higher level concurrent.futures module by providing clearer links from the lower level threading and multiprocessing modules.

  • gh-95957: What’s New 3.11 now has instructions for how to provide compiler and linker flags for Tcl/Tk and OpenSSL on RHEL 7 and CentOS 7.

Tests

  • gh-95243: Mitigate the inherent race condition from using find_unused_port() in testSockName() by trying to find an unused port a few times before failing. Patch by Ross Burton.

Build

  • gh-94682: Build and test with OpenSSL 1.1.1q

Windows

  • gh-96577: Fixes a potential buffer overrun in msilib.

  • gh-96559: Fixes the Windows launcher not using the compatible interpretation of default tags found in configuration files when no tag was passed to the command.

Python 3.11.0 release candidate 1

Release date: 2022-08-05

Core and Builtins

  • gh-95150: Update code object hashing and equality to consider all debugging and exception handling tables. This fixes an issue where certain non-identical code objects could be “deduplicated” during compilation.

  • gh-95355: _PyPegen_Parser_New now properly detects token memory allocation errors. Patch by Honglin Zhu.

  • gh-90081: Run Python code in tracer/profiler function at full speed. Fixes slowdown in earlier versions of 3.11.

  • gh-95324: Emit a warning in debug mode if an object does not call PyObject_GC_UnTrack() before deallocation. Patch by Pablo Galindo.

  • gh-95185: Prevented crashes in the AST constructor when compiling some absurdly long expressions like "+0"*1000000. RecursionError is now raised instead. Patch by Pablo Galindo

  • gh-93351: ast.AST node positions are now validated when provided to compile() and other related functions. If invalid positions are detected, a ValueError will be raised.

  • gh-94938: Fix error detection in some builtin functions when keyword argument name is an instance of a str subclass with overloaded __eq__ and __hash__. Previously it could cause SystemError or other undesired behavior.

Library

Documentation

  • gh-91207: Fix stylesheet not working in Windows CHM htmlhelp docs and add warning that they are deprecated. Contributed by C.A.M. Gerlach.

  • gh-95451: Update library documentation with availability information on WebAssembly platforms wasm32-emscripten and wasm32-wasi.

  • gh-95415: Use consistent syntax for platform availability. The directive now supports a content body and emits a warning when it encounters an unknown platform.

  • gh-86128: Document a limitation in ThreadPoolExecutor where its exit handler is executed before any handlers in atexit.

Tests

  • gh-95573: Lib/test/test_asyncio/test_ssl.py exposed a bug in the macOS kernel where intense concurrent load on non-blocking sockets occasionally causes errno.ENOBUFS (“No buffer space available”) to be emitted. FB11063974 filed with Apple, in the mean time as a workaround buffer size used in tests on macOS is decreased to avoid intermittent failures. Patch by Fantix King.

  • gh-95280: Fix problem with test_ssl test_get_ciphers on systems that require perfect forward secrecy (PFS) ciphers.

  • gh-94675: Add a regression test for re exponentional slowdown when using rjsmin.

Build

  • gh-94801: Fix a regression in configure script that caused some header checks to ignore custom CPPFLAGS. The regression was introduced in gh-94802.

  • gh-95145: wasm32-wasi builds no longer depend on WASIX’s pthread stubs. Python now has its own stubbed pthread API.

  • gh-95174: Python now detects missing dup function in WASI and works around some missing errno, select, and socket constants.

  • gh-95174: Python now skips missing socket functions and methods on WASI. WASI can only create sockets from existing fd / accept and has no netdb.

  • gh-95085: Platforms wasm32-unknown-emscripten and wasm32-unknown-wasi have been promoted to PEP 11 tier 3 platform support.

Windows

  • gh-95656: Enable the enable_load_extension() sqlite3 API.

  • gh-95587: Fixes some issues where the Windows installer would incorrectly detect certain features of an existing install when upgrading.

  • gh-94399: Restores the behaviour of Python Launcher for Windows for /usr/bin/env shebang lines, which will now search PATH for an executable matching the given command. If none is found, the usual search process is used.

  • gh-95445: Fixes the unsuccessful removal of the HTML document directory when uninstalling with Windows msi.

  • gh-95359: Fix Python Launcher for Windows handling of py.ini commands (it was incorrectly expecting a py_ prefix on keys) and crashes when reading per-user configuration file.

  • gh-95285: Fix Python Launcher for Windows handling of command lines where it is only passed a short executable name.

IDLE

  • gh-65802: Document handling of extensions in Save As dialogs.

  • gh-95191: Include prompts when saving Shell (interactive input and output).

  • gh-95511: Fix the Shell context menu copy-with-prompts bug of copying an extra line when one selects whole lines.

  • gh-95471: In the Edit menu, move Select All and add a new separator.

  • gh-95411: Enable using IDLE’s module browser with .pyw files.

  • gh-89610: Add .pyi as a recognized extension for IDLE on macOS. This allows opening stub files by double clicking on them in the Finder.

C API

Python 3.11.0 beta 5

Release date: 2022-07-25

Core and Builtins

  • gh-93351: ast.AST node positions are now validated when provided to compile() and other related functions. If invalid positions are detected, a ValueError will be raised.

  • gh-94438: Fix an issue that caused extended opcode arguments and some conditional pops to be ignored when calculating valid jump targets for assignments to the f_lineno attribute of frame objects. In some cases, this could cause inconsistent internal state, resulting in a hard crash of the interpreter.

  • gh-95060: Undocumented PyCode_Addr2Location function now properly returns when addrq argument is less than zero.

  • gh-95113: Replace all EXTENDED_ARG_QUICK instructions with basic EXTENDED_ARG instructions in unquickened code. Consumers of non-adaptive bytecode should be able to handle extended arguments the same way they were handled in CPython 3.10 and older.

  • gh-91409: Fix incorrect source location info caused by certain optimizations in the bytecode compiler.

  • gh-94036: Fix incorrect source location info for some multi-line attribute accesses and method calls.

  • gh-94739: Allow jumping within, out of, and across exception handlers in the debugger.

  • gh-94949: ast.parse() will no longer parse parenthesized context managers when passed feature_version less than (3, 9). Patch by Shantanu Jain.

  • gh-94947: ast.parse() will no longer parse assignment expressions when passed feature_version less than (3, 8). Patch by Shantanu Jain.

  • gh-91256: Ensures the program name is known for help text during interpreter startup.

  • gh-94869: Fix the column offsets for some expressions in multi-line f-strings ast nodes. Patch by Pablo Galindo.

  • gh-94822: Fix an issue where lookups of metaclass descriptors may be ignored when an identically-named attribute also exists on the class itself.

  • gh-91153: Fix an issue where a bytearray item assignment could crash if it’s resized by the new value’s __index__() method.

  • gh-90699: Fix reference counting bug in bool.__repr__(). Patch by Kumar Aditya.

Library

  • gh-95087: Fix IndexError in parsing invalid date in the email module.

  • gh-95199: Upgrade bundled setuptools to 63.2.0.

  • gh-95194: Upgrade bundled pip to 22.2.

  • gh-95132: Fix a sqlite3 regression where *args and **kwds were incorrectly relayed from connect() to the Connection factory. The regression was introduced in 3.11a1 with PR 24421 (gh-85128). Patch by Erlend E. Aasland.`

  • gh-93157: Fix fileinput module didn’t support errors option when inplace is true.

  • gh-95105: wsgiref.types.InputStream.__iter__() should return Iterator[bytes], not Iterable[bytes]. Patch by Shantanu Jain.

  • gh-94857: Fix refleak in _io.TextIOWrapper.reconfigure. Patch by Kumar Aditya.

  • gh-94821: Fix binding of unix socket to empty address on Linux to use an available address from the abstract namespace, instead of “0”.

  • gh-89988: Fix memory leak in pickle.Pickler when looking up dispatch_table. Patch by Kumar Aditya.

  • bpo-47025: Drop support for bytes on sys.path.

Tests

  • gh-95212: Make multiprocessing test case test_shared_memory_recreate parallel-safe.

Build

  • gh-94847: Fixed _decimal module build issue on GCC when compiling with LTO and pydebug. Debug builds no longer force inlining of functions.

  • gh-94841: Fix the possible performance regression of PyObject_Free() compiled with MSVC version 1932.

  • gh-94801: configure now uses custom flags like ZLIB_CFLAGS and ZLIB_LIBS when searching for headers and libraries.

  • gh-94773: deepfreeze.py now supports code object with frozensets that contain incompatible, unsortable types.

Windows

  • gh-90844: Allow virtual environments to correctly launch when they have spaces in the path.

  • gh-94772: Fix incorrect handling of shebang lines in py.exe launcher

C API

  • gh-92678: Adds unstable C-API functions _PyObject_VisitManagedDict and _PyObject_ClearManagedDict to allow C extensions to allow the VM to manage their object’s dictionaries.

  • gh-94930: Fix SystemError raised when PyArg_ParseTupleAndKeywords() is used with # in (...) but without PY_SSIZE_T_CLEAN defined.

  • gh-94864: Fix PyArg_Parse* with deprecated format units “u” and “Z”. It returned 1 (success) when warnings are turned into exceptions.

  • gh-94731: Python again uses C-style casts for most casting operations when compiled with C++. This may trigger compiler warnings, if they are enabled with e.g. -Wold-style-cast or -Wzero-as-null-pointer-constant options for g++.

Python 3.11.0 beta 4

Release date: 2022-07-11

Security

  • gh-87389: http.server: Fix an open redirection vulnerability in the HTTP server when an URI path starts with //. Vulnerability discovered, and initial fix proposed, by Hamza Avvan.

  • gh-79096: LWPCookieJar and MozillaCookieJar create files with file mode 600 instead of 644 (Microsoft Windows is not affected)

  • gh-92888: Fix memoryview use after free when accessing the backing buffer in certain cases.

  • gh-68966: The deprecated mailcap module now refuses to inject unsafe text (filenames, MIME types, parameters) into shell commands. Instead of using such text, it will warn and act as if a match was not found (or for test commands, as if the test failed).

Core and Builtins

  • gh-94694: Fix an issue that could cause code with multi-line method lookups to have misleading or incorrect column offset information. In some cases (when compiling a hand-built AST) this could have resulted in a hard crash of the interpreter.

  • gh-93252: Fix an issue that caused internal frames to outlive failed Python function calls, possibly resulting in memory leaks or hard interpreter crashes.

  • gh-94215: Fix an issue where exceptions raised by line-tracing events would cause frames to be left in an invalid state, possibly resulting in a hard crash of the interpreter.

  • gh-92228: Disable the compiler’s inline-small-exit-blocks optimization for exit blocks that are associated with source code lines. This fixes a bug where the debugger cannot tell where an exception handler ends and the following code block begins.

  • gh-94485: Line number of a module’s RESUME instruction is set to 0 as specified in PEP 626.

  • gh-94438: Account for instructions that can push NULL to the stack when setting line number in a frame. Prevents some (unlikely) crashes.

  • gh-91719: Reload opcode when raising unknown opcode error in the interpreter main loop, for C compilers to generate dispatching code independently.

  • gh-94329: Compile and run code with unpacking of extremely large sequences (1000s of elements). Such code failed to compile. It now compiles and runs correctly.

  • gh-94360: Fixed a tokenizer crash when reading encoded files with syntax errors from stdin with non utf-8 encoded text. Patch by Pablo Galindo

  • gh-88116: Fix an issue when reading line numbers from code objects if the encoded line numbers are close to INT_MIN. Patch by Pablo Galindo

  • gh-94262: Don’t create frame objects for incomplete frames. Prevents the creation of generators and closures from being observable to Python and C extensions, restoring the behavior of 3.10 and earlier.

  • gh-94192: Fix error for dictionary literals with invalid expression as value.

  • gh-93883: Revise the display strategy of traceback enhanced error locations. The indicators are only shown when the location doesn’t span the whole line.

  • gh-94021: Fix unreachable code warning in Python/specialize.c.

  • gh-93516: Store offset of first traceable instruction in code object to avoid having to recompute it for each instruction when tracing.

  • gh-93516: Lazily create a table mapping bytecode offsets to line numbers to speed up calculation of line numbers when tracing.

  • gh-89828: types.GenericAlias no longer relays the __class__ attribute. For example, isinstance(list[int], type) no longer returns True.

  • gh-93671: Fix some exponential backtrace case happening with deeply nested sequence patterns in match statements. Patch by Pablo Galindo

  • gh-93662: Make sure that the end column offsets are correct in multi-line method calls. Previously, the end column could precede the column offset.

  • gh-93461: importlib.invalidate_caches() now drops entries from sys.path_importer_cache with a relative path as name. This solves a caching issue when a process changes its current working directory.

    FileFinder no longer inserts a dot in the path, e.g. /egg/./spam is now /egg/spam.

  • gh-93418: Fixed an assert where an f-string has an equal sign ‘=’ following an expression, but there’s no trailing brace. For example, f”{i=”.

  • gh-93382: Cache the result of PyCode_GetCode() function to restore the O(1) lookup of the co_code attribute.

  • gh-93354: Use exponential backoff for specialization counters in the interpreter. Can reduce the number of failed specializations significantly and avoid slowdown for those parts of a program that are not suitable for specialization.

  • gh-93021: Fix the __text_signature__ for __get__() methods implemented in C. Patch by Jelle Zijlstra.

  • gh-92930: Fixed a crash in _pickle.c from mutating collections during __reduce__ or persistent_id.

  • gh-92914: Always round the allocated size for lists up to the nearest even number.

  • gh-92858: Improve error message for some suites with syntax error before ‘:’

  • bpo-46142: Make --help output shorter by moving some info to the new --help-env and --help-xoptions command-line options. Also add --help-all option to print complete usage.

Library

  • gh-94736: Fix crash when deallocating an instance of a subclass of _multiprocessing.SemLock. Patch by Kumar Aditya.

  • gh-94637: SSLContext.set_default_verify_paths() now releases the GIL around SSL_CTX_set_default_verify_paths call. The function call performs I/O and CPU intensive work.

  • gh-94607: Fix subclassing complex generics with type variables in typing. Previously an error message saying Some type variables ... are not listed in Generic[...] was shown. typing no longer populates __parameters__ with the __parameters__ of a Python class.

  • gh-93910: The ability to access the other values of an enum on an enum (e.g. Color.RED.BLUE) has been restored in order to fix a performance regression.

  • gh-93896: Fix asyncio.run() and unittest.IsolatedAsyncioTestCase to always the set event loop as it was done in Python 3.10 and earlier. Patch by Kumar Aditya.

  • gh-94510: Re-entrant calls to sys.setprofile() and sys.settrace() now raise RuntimeError. Patch by Pablo Galindo.

  • gh-92336: Fix bug where linecache.getline() fails on bad files with UnicodeDecodeError or SyntaxError. It now returns an empty string as per the documentation.

  • gh-94398: Once a asyncio.TaskGroup has started shutting down (i.e., at least one task has failed and the task group has started cancelling the remaining tasks), it should not be possible to add new tasks to the task group.

  • gh-94254: Fixed types of struct module to be immutable. Patch by Kumar Aditya.

  • gh-94207: Made _struct.Struct GC-tracked in order to fix a reference leak in the _struct module.

  • gh-91742: Fix pdb crash after jump caused by a null pointer dereference. Patch by Kumar Aditya.

  • gh-94101: Manual instantiation of ssl.SSLSession objects is no longer allowed as it lead to misconfigured instances that crashed the interpreter when attributes where accessed on them.

  • gh-84753: inspect.iscoroutinefunction(), inspect.isgeneratorfunction(), and inspect.isasyncgenfunction() now properly return True for duck-typed function-like objects like instances of unittest.mock.AsyncMock.

    This makes inspect.iscoroutinefunction() consistent with the behavior of asyncio.iscoroutinefunction(). Patch by Mehdi ABAAKOUK.

  • gh-94028: Fix a regression in the sqlite3 where statement objects were not properly cleared and reset after use in cursor iters. The regression was introduced by PR 27884 in Python 3.11a1. Patch by Erlend E. Aasland.

  • gh-93820: Pickle enum.Flag by name.

  • gh-93847: Fix repr of enum of generic aliases.

  • gh-91404: Revert the re memory leak when a match is terminated by a signal or memory allocation failure as the implemented fix caused a major performance regression.

  • gh-83499: Fix double closing of file description in tempfile.

  • gh-93820: Fixed a regression when copy.copy()-ing enum.Flag with multiple flag members.

  • gh-79512: Fixed names and __module__ value of weakref classes ReferenceType, ProxyType, CallableProxyType. It makes them pickleable.

  • gh-91389: Fix an issue where dis utilities could report missing or incorrect position information in the presence of CACHE entries.

  • gh-93626: Set __future__.annotations to have a None mandatoryRelease to indicate that it is currently ‘TBD’.

  • gh-90473: Emscripten and WASI have no home directory and cannot provide PEP 370 user site directory.

  • gh-90494: copy.copy() and copy.deepcopy() now always raise a TypeError if __reduce__() returns a tuple with length 6 instead of silently ignore the 6th item or produce incorrect result.

  • gh-90549: Fix a multiprocessing bug where a global named resource (such as a semaphore) could leak when a child process is spawned (as opposed to forked).

  • gh-93521: Fixed a case where dataclasses would try to add __weakref__ into the __slots__ for a dataclass that specified weakref_slot=True when it was already defined in one of its bases. This resulted in a TypeError upon the new class being created.

  • gh-79579: sqlite3 now correctly detects DML queries with leading comments. Patch by Erlend E. Aasland.

  • gh-93421: Update sqlite3.Cursor.rowcount when a DML statement has run to completion. This fixes the row count for SQL queries like UPDATE ... RETURNING. Patch by Erlend E. Aasland.

  • gh-91162: Support splitting of unpacked arbitrary-length tuple over TypeVar and TypeVarTuple parameters. For example:

    • A[T, *Ts][*tuple[int, ...]] -> A[int, *tuple[int, ...]]

    • A[*Ts, T][*tuple[int, ...]] -> A[*tuple[int, ...], int]

  • gh-93353: Fix the importlib.resources.as_file() context manager to remove the temporary file if destroyed late during Python finalization: keep a local reference to the os.remove() function. Patch by Victor Stinner.

  • gh-83658: Make multiprocessing.Pool raise an exception if maxtasksperchild is not None or a positive int.

  • gh-93156: Accessing the pathlib.PurePath.parents sequence of an absolute path using negative index values produced incorrect results.

  • gh-74696: shutil.make_archive() no longer temporarily changes the current working directory during creation of standard .zip or tar archives.

  • gh-89973: Fix re.error raised in fnmatch if the pattern contains a character range with upper bound lower than lower bound (e.g. [c-a]). Now such ranges are interpreted as empty ranges.

  • gh-92932: Now dis() and get_instructions() handle operand values for instructions prefixed by EXTENDED_ARG_QUICK. Patch by Sam Gross and Donghee Na.

  • gh-91577: Move imports in SharedMemory methods to module level so that they can be executed late in python finalization.

  • gh-91456: Deprecate current default auto() behavior: In 3.13 the default will be for for auto() to always return the largest member value incremented by 1, and to raise if incompatible value types are used.

  • bpo-47231: Fixed an issue with inconsistent trailing slashes in tarfile longname directories.

  • bpo-46755: In QueueHandler, clear stack_info from LogRecord to prevent stack trace from being written twice.

  • bpo-46197: Fix ensurepip environment isolation for subprocess running pip.

  • bpo-45924: Fix asyncio incorrect traceback when future’s exception is raised multiple times. Patch by Kumar Aditya.

  • bpo-34828: sqlite3.Connection.iterdump() now handles databases that use AUTOINCREMENT in one or more tables.

Documentation

Tests

  • gh-91330: Added more tests for dataclasses to cover behavior with data descriptor-based fields.

  • gh-94208: test_ssl is now checking for supported TLS version and protocols in more tests.

  • gh-94315: Tests now check for DAC override capability instead of relying on os.geteuid().

  • gh-93951: In test_bdb.StateTestCase.test_skip, avoid including auxiliary importers.

  • gh-93957: Provide nicer error reporting from subprocesses in test_venv.EnsurePipTest.test_with_pip.

  • gh-84461: run_tests.py now handles cross compiling env vars correctly and pass HOSTRUNNER to regression tests.

  • gh-93616: test_modulefinder now creates a temporary directory in ModuleFinderTest.setUp() instead of module scope.

  • gh-93575: Fix issue with test_unicode test_raiseMemError. The test case now use test.support.calcobjsize to calculate size of PyUnicode structs. sys.getsizeof() may return different size when string has UTF-8 memory.

  • gh-90473: WASI does not have a chmod(2) syscall. os.chmod() is now a dummy function on WASI. Skip all tests that depend on working os.chmod().

  • gh-90473: Skip tests on WASI that require symlinks with absolute paths.

  • gh-57539: Increase calendar test coverage for calendar.LocaleTextCalendar.formatweekday().

  • gh-90473: Skip symlink tests on WASI. wasmtime uses openat2(2) with RESOLVE_BENEATH flag, which prevents symlinks with absolute paths.

  • gh-89858: Fix test_embed for out-of-tree builds. Patch by Kumar Aditya.

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in test_imaplib.py.

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in test_zipimport.py

  • bpo-47016: Create a GitHub Actions workflow for verifying bundled pip and setuptools. Patch by Illia Volochii and Adam Turner.

Build

  • gh-94404: makesetup now works around an issue with sed on macOS and uses correct CFLAGS for object files that end up in a shared extension. Module CFLAGS are used before PY_STDMODULE_CFLAGS to avoid clashes with system headers.

  • gh-93584: Address race condition in Makefile when installing a PGO build. All test and install targets now depend on all target.

  • gh-93491: configure now detects and reports PEP 11 support tiers.

Windows

  • gh-93824: Drag and drop of files onto Python files in Windows Explorer has been enabled for Windows ARM64.

  • bpo-42658: Support native Windows case-insensitive path comparisons by using LCMapStringEx instead of str.lower() in ntpath.normcase(). Add LCMapStringEx to the _winapi module.

Tools/Demos

  • gh-94538: Fix Argument Clinic output to custom file destinations. Patch by Erlend E. Aasland.

  • gh-94430: Allow parameters named module and self with custom C names in Argument Clinic. Patch by Erlend E. Aasland

C API

Python 3.11.0 beta 3

Release date: 2022-06-01

Core and Builtins

  • gh-93359: Ensure that custom ast nodes without explicit end positions can be compiled. Patch by Pablo Galindo.

  • gh-93345: Fix a crash in substitution of a TypeVar in nested generic alias after TypeVarTuple.

Build

  • gh-69093: Fix Modules/Setup.stdlib.in rule for _sqlite3 extension.

Python 3.11.0 beta 2

Release date: 2022-05-30

Core and Builtins

  • gh-84694: The --experimental-isolated-subinterpreters configure option and EXPERIMENTAL_ISOLATED_SUBINTERPRETERS macro have been removed.

  • gh-91924: Fix __lltrace__ debug feature if the stdout encoding is not UTF-8. Patch by Victor Stinner.

  • gh-93061: Backward jumps after async for loops are no longer given dubious line numbers.

  • gh-93065: Fix contextvars HAMT implementation to handle iteration over deep trees.

    The bug was discovered and fixed by Eli Libman. See MagicStack/immutables#84 for more details.

  • gh-90473: Decrease default recursion limit on WASI to address limited call stack size.

  • gh-92804: Fix memory leak in memoryview iterator as it was not finalized at exit. Patch by Kumar Aditya.

  • gh-92236: Remove spurious “LINE” event when starting a generator or coroutine, visible tracing functions implemented in C.

  • gh-92619: Make the compiler duplicate an exit block only if none of its instructions have a lineno (previously only the first instruction in the block was checked, leading to unnecessarily duplicated blocks).

  • gh-92261: Fix hang when trying to iterate over a typing.Union.

Library

  • gh-93297: Make asyncio task groups prevent child tasks from being GCed

  • gh-90817: The locale.resetlocale() function is deprecated and will be removed in Python 3.13. Use locale.setlocale(locale.LC_ALL, "") instead. Patch by Victor Stinner.

  • gh-92728: The re.template() function and the corresponding re.TEMPLATE and re.T flags are restored after they were removed in 3.11.0b1, but they are now deprecated, so they might be removed from Python 3.13.

  • gh-93044: No longer convert the database argument of sqlite3.connect() to bytes before passing it to the factory.

  • gh-93010: In a very special case, the email package tried to append the nonexistent InvalidHeaderError to the defect list. It should have been InvalidHeaderDefect.

  • gh-92675: Fix venv.ensure_directories() to accept pathlib.Path arguments in addition to str paths. Patch by David Foster.

  • gh-87901: Removed the encoding argument from os.popen() that was added in 3.11b1.

  • gh-91922: Fix function sqlite.connect() and the sqlite.Connection constructor on non-UTF-8 locales. Also, they now support bytes paths non-decodable with the current FS encoding.

  • gh-92839: Fixed crash resulting from calling bisect.insort() or bisect.insort_left() with the key argument not equal to None.

  • gh-90473: subprocess now fails early on Emscripten and WASI platforms to work around missing os.pipe() on WASI.

  • gh-92671: Fixed ast.unparse() for empty tuples in the assignment target context.

  • gh-91581: utcfromtimestamp() no longer attempts to resolve fold in the pure Python implementation, since the fold is never 1 in UTC. In addition to being slightly faster in the common case, this also prevents some errors when the timestamp is close to datetime.min. Patch by Paul Ganssle.

  • gh-92550: Fix pathlib.Path.rglob() for empty pattern.

  • gh-92530: Fix an issue that occurred after interrupting threading.Condition.notify().

  • gh-92531: The statistics.median_grouped() function now always return a float. Formerly, it did not convert the input type when for sequences of length one.

  • gh-91810: ElementTree method write() and function tostring() now use the text file’s encoding (“UTF-8” if not available) instead of locale encoding in XML declaration when encoding="unicode" is specified.

  • gh-90622: Worker processes for concurrent.futures.ProcessPoolExecutor are no longer spawned on demand (a feature added in 3.9) when the multiprocessing context start method is "fork" as that can lead to deadlocks in the child processes due to a fork happening while threads are running.

  • gh-91581: Remove an unhandled error case in the C implementation of calls to datetime.fromtimestamp with no time zone (i.e. getting a local time from an epoch timestamp). This should have no user-facing effect other than giving a possibly more accurate error message when called with timestamps that fall on 10000-01-01 in the local time. Patch by Paul Ganssle.

  • bpo-39064: zipfile.ZipFile now raises zipfile.BadZipFile instead of ValueError when reading a corrupt zip file in which the central directory offset is negative.

  • bpo-45393: Fix the formatting for await x and not x in the operator precedence table when using the help() system.

  • bpo-28249: Set doctest.DocTest.lineno to None when object does not have __doc__.

  • bpo-45046: Add support of context managers in unittest: methods enterContext() and enterClassContext() of class TestCase, method enterAsyncContext() of class IsolatedAsyncioTestCase and function unittest.enterModuleContext().

  • bpo-42627: Fix incorrect parsing of Windows registry proxy settings

Documentation

Tests

  • gh-92670: Skip test_shutil.TestCopy.test_copyfile_nonexistent_dir test on AIX as the test uses a trailing slash to force the OS consider the path as a directory, but on AIX the trailing slash has no effect and is considered as a file.

Build

  • gh-90473: Disable pymalloc and increase stack size on wasm32-wasi.

  • bpo-34449: Drop invalid compiler switch -fPIC for HP aCC on HP-UX. Patch by Michael Osipov.

Windows

  • gh-92817: Ensures that py.exe will prefer an active virtual environment over default tags specified with environment variables or through a py.ini file.

  • gh-92984: Explicitly disable incremental linking for non-Debug builds

  • gh-92841: asyncio no longer throws RuntimeError: Event loop is closed on interpreter exit after asynchronous socket activity. Patch by Oleg Iarygin.

  • bpo-46907: Update Windows installer to use SQLite 3.38.4.

C API

  • gh-92898: Fix C++ compiler warnings when casting function arguments to PyObject*. Patch by Serge Guelton.

  • gh-92913: Ensures changes to PyConfig.module_search_paths are ignored unless PyConfig.module_search_paths_set is set

  • gh-92781: Avoid mixing declarations and code in the C API to fix the compiler warning: “ISO C90 forbids mixed declarations and code” [-Werror=declaration-after-statement]. Patch by Victor Stinner.

Python 3.11.0 beta 1

Release date: 2022-05-06

Security

  • gh-57684: Add the -P command line option and the PYTHONSAFEPATH environment variable to not prepend a potentially unsafe path to sys.path. Patch by Victor Stinner.

Core and Builtins

  • gh-89519: Chaining classmethod descriptors (introduced in bpo-19072) is deprecated. It can no longer be used to wrap other descriptors such as property(). The core design of this feature was flawed, and it caused a number of downstream problems.

  • gh-92345: pymain_run_python() now imports readline and rlcompleter before sys.path is extended to include the current working directory of an interactive interpreter. Non-interactive interpreters are not affected.

  • bpo-43857: Improve the AttributeError message when deleting a missing attribute. Patch by Géry Ogam.

  • gh-92245: Make sure that PEP 523 is respected in all cases. In 3.11a7, specialization may have prevented Python-to-Python calls respecting PEP 523.

  • gh-92203: Add a closure keyword-only parameter to exec(). It can only be specified when exec-ing a code object that uses free variables. When specified, it must be a tuple, with exactly the number of cell variables referenced by the code object. closure has a default value of None, and it must be None if the code object doesn’t refer to any free variables.

  • gh-91173: Disable frozen modules in debug builds. Patch by Kumar Aditya.

  • gh-92114: Improve error message when subscript a type with __class_getitem__ set to None.

  • gh-92112: Fix crash triggered by an evil custom mro() on a metaclass.

  • gh-92063: The PRECALL_METHOD_DESCRIPTOR_FAST_WITH_KEYWORDS instruction now ensures methods are called only on objects of the correct type.

  • gh-92031: Deoptimize statically allocated code objects during Py_FINALIZE() so that future _PyCode_Quicken calls always start with unquickened code.

  • gh-92036: Fix a crash in subinterpreters related to the garbage collector. When a subinterpreter is deleted, untrack all objects tracked by its GC. To prevent a crash in deallocator functions expecting objects to be tracked by the GC, leak a strong reference to these objects on purpose, so they are never deleted and their deallocator functions are not called. Patch by Victor Stinner.

  • gh-92032: The interpreter can now autocomplete soft keywords, as of now match, case, and _ (wildcard pattern) from PEP 634.

  • gh-87999: The warning emitted by the Python parser for a numeric literal immediately followed by keyword has been changed from deprecation warning to syntax warning.

  • gh-91869: Fix an issue where specialized opcodes with extended arguments could produce incorrect tracing output or lead to assertion failures.

  • gh-91603: Speed up types.UnionType instantiation. Based on patch provided by Yurii Karabas.

  • gh-89373: If Python is built in debug mode, Python now ensures that deallocator functions leave the current exception unchanged. Patch by Victor Stinner.

  • gh-91632: Fix a minor memory leak at exit: release the memory of the generic_alias_iterator type. Patch by Donghee Na.

  • gh-81548: Octal escapes with value larger than 0o377 now produce a DeprecationWarning. In a future Python version they will be a SyntaxWarning and eventually a SyntaxError.

  • bpo-43950: Use a single compact table for line starts, ends and column offsets. Reduces memory consumption for location info by half

  • gh-91102: Use Argument Clinic for EncodingMap. Patch by Oleg Iarygin.

  • gh-91636: Fixed a crash in a garbage-collection edge-case, in which a PyFunction_Type.tp_clear function could leave a python function object in an inconsistent state.

  • gh-91603: Speed up isinstance() and issubclass() checks for types.UnionType. Patch by Yurii Karabas.

  • gh-91625: Fixed a bug in which adaptive opcodes ignored any preceding EXTENDED_ARGs on specialization failure.

  • gh-78607: The LLTRACE special build now looks for the name __lltrace__ defined in module globals, rather than the name __ltrace__, which had been introduced as a typo.

  • gh-91576: Speed up iteration of ascii strings by 50%. Patch by Kumar Aditya.

  • gh-89279: Improve interpreter performance on Windows by inlining a few specific macros.

  • gh-91502: Add a new _PyFrame_IsEntryFrame() API function, to check if a PyFrameObject is an entry frame. Patch by Pablo Galindo.

  • gh-91266: Refactor the bytearray strip methods strip, lstrip and rstrip to use a common implementation.

  • gh-91479: Replaced the __note__ field of BaseException (added in an earlier version of 3.11) with the final design of PEP 678. Namely, BaseException gets an add_note() method, and its __notes__ field is created when necessary.

  • gh-46055: Speed up right shift of negative integers, by removing unnecessary creation of temporaries. Original patch by Xinhang Xu, reworked by Mark Dickinson.

  • gh-91462: Make the interpreter’s low-level tracing (lltrace) feature output more readable by displaying opcode names (rather than just numbers), and by displaying stack contents before each opcode.

  • gh-89455: Fixed an uninitialized bool value in the traceback printing code path that was introduced by the initial bpo-45292 exception groups work.

  • gh-91421: Fix a potential integer overflow in _Py_DecodeUTF8Ex.

  • gh-91428: Add static const char *const _PyOpcode_OpName[256] = {...}; to opcode.h for debug builds to assist in debugging the Python interpreter. It is now more convenient to make various forms of debugging output more human-readable by including opcode names rather than just the corresponding decimal digits.

  • bpo-47120: Make POP_JUMP_IF_TRUE, POP_JUMP_IF_FALSE, POP_JUMP_IF_NONE and POP_JUMP_IF_NOT_NONE virtual, mapping to new relative jump opcodes.

  • bpo-45317: Add internal documentation explaining design of new (for 3.11) frame stack.

  • bpo-47197: ctypes used to mishandle void return types, so that for instance a function declared like ctypes.CFUNCTYPE(None, ctypes.c_int) would be called with signature int f(int) instead of void f(int). Wasm targets require function pointers to be called with the correct signatures so this led to crashes. The problem is now fixed.

  • bpo-47120: Make opcodes JUMP_IF_TRUE_OR_POP and JUMP_IF_FALSE_OR_POP relative rather than absolute.

  • bpo-47177: Replace the f_lasti member of the internal _PyInterpreterFrame structure with a prev_instr pointer, which reduces overhead in the main interpreter loop. The f_lasti attribute of Python-layer frame objects is preserved for backward-compatibility.

  • bpo-46961: Integer mod/remainder operations, including the three-argument form of pow(), now consistently return ints from the global small integer cache when applicable.

  • bpo-46962: Classes and functions that unconditionally declared their docstrings ignoring the --without-doc-strings compilation flag no longer do so.

    The classes affected are ctypes.UnionType, pickle.PickleBuffer, testcapi.RecursingInfinitelyError, and types.GenericAlias.

    The functions affected are 24 methods in ctypes.

    Patch by Oleg Iarygin.

  • bpo-46942: Use Argument Clinic for the types.MethodType constructor. Patch by Oleg Iarygin.

  • bpo-46764: Fix wrapping bound methods with @classmethod

  • bpo-43464: Optimize set.intersection() for non-set arguments.

  • bpo-46721: Optimize set.issuperset() for non-set argument.

  • bpo-46509: Add type-specialized versions of the Py_DECREF(), and use them for float, int, str, bool, and None to avoid pointer-chasing at runtime where types are known at C compile time.

  • bpo-46045: Do not use POSIX semaphores on NetBSD

  • bpo-36819: Fix crashes in built-in encoders with error handlers that return position less or equal than the starting position of non-encodable characters.

  • bpo-34093: marshal.dumps() uses FLAG_REF for all interned strings. This makes output more deterministic and helps reproducible build.

  • bpo-26579: Added object.__getstate__ which provides the default implementation of the __getstate__() method.

    Copying and pickling instances of subclasses of builtin types bytearray, set, frozenset, collections.OrderedDict, collections.deque, weakref.WeakSet, and datetime.tzinfo now copies and pickles instance attributes implemented as slots.

Library

  • gh-87901: Add the encoding parameter to os.popen().

  • gh-90997: Fix an issue where dis utilities may interpret populated inline cache entries as valid instructions.

  • gh-92332: Deprecate typing.Text (removal of the class is currently not planned). Patch by Alex Waygood.

  • gh-78157: Deprecate nested classes in enum definitions becoming members – in 3.13 they will be normal classes; add member and nonmember functions to allow control over results now.

  • gh-92356: Fixed a performance regression in ctypes function calls.

  • gh-90997: Show the actual named values stored in inline caches when show_caches=True is passed to dis utilities.

  • gh-92301: Prefer close_range() to iterating over procfs for file descriptor closing in subprocess for better performance.

  • gh-67248: Sort the miscellaneous topics in Cmd.do_help()

  • gh-92210: Port socket.__init__ to Argument Clinic. Patch by Cinder.

  • gh-80010: Add support for generalized ISO 8601 parsing to datetime.datetime.fromisoformat(), datetime.date.fromisoformat() and datetime.time.fromisoformat(). Patch by Paul Ganssle.

  • gh-92118: Fix a 3.11 regression in contextmanager(), which caused it to propagate exceptions with incorrect tracebacks.

  • gh-90887: Adding COPYFILE_STAT, COPYFILE_ACL and COPYFILE_XATTR constants for os.fcopyfile() available in macOs.

  • gh-91215: For @dataclass, add weakref_slot. Default is False. If True, and if slots=True, add a slot named “__weakref__”, which will allow instances to be weakref’d. Contributed by Eric V. Smith

  • gh-85984: New function os.login_tty() for Unix.

  • gh-92128: Add __class_getitem__() to logging.LoggerAdapter and logging.StreamHandler, allowing them to be parameterized at runtime. Patch by Alex Waygood.

  • gh-92049: Forbid pickling constants re._constants.SUCCESS etc. Previously, pickling did not fail, but the result could not be unpickled.

  • gh-92062: inspect.Parameter now raises ValueError if name is a keyword, in addition to the existing check that it is an identifier.

  • gh-87390: Add an __unpacked__ attribute to types.GenericAlias. Patch by Jelle Zijlstra.

  • gh-88089: Add support for generic typing.NamedTuple.

  • gh-91996: New http.HTTPMethod enum to represent all the available HTTP request methods in a convenient way

  • gh-91984: Modified test strings in test_argparse.py to not contain trailing spaces before end of line.

  • gh-91952: Add encoding="locale" support to TextIOWrapper.reconfigure().

  • gh-91954: Add encoding and errors arguments to subprocess.getoutput() and subprocess.getstatusoutput().

  • bpo-47029: Always close the read end of the pipe used by multiprocessing.Queue after the last write of buffered data to the write end of the pipe to avoid BrokenPipeError at garbage collection and at multiprocessing.Queue.close() calls. Patch by Géry Ogam.

  • gh-91928: Add datetime.UTC alias for datetime.timezone.utc.

    Patch by Kabir Kwatra.

  • gh-68966: The mailcap module is now deprecated and will be removed in Python 3.13. See PEP 594 for the rationale and the mimetypes module for an alternative. Patch by Victor Stinner.

  • gh-91401: Provide a way to disable subprocess use of vfork() just in case it is ever needed and document the existing mechanism for posix_spawn().

  • gh-64783: Fix signal.NSIG value on FreeBSD to accept signal numbers greater than 32, like signal.SIGRTMIN and signal.SIGRTMAX. Patch by Victor Stinner.

  • gh-91910: Add missing f prefix to f-strings in error messages from the multiprocessing and asyncio modules.

  • gh-91860: Add typing.dataclass_transform(), implementing PEP 681. Patch by Jelle Zijlstra.

  • gh-91832: Add required attribute to argparse.Action repr output.

  • gh-91827: In the tkinter module add method info_patchlevel() which returns the exact version of the Tcl library as a named tuple similar to sys.version_info.

  • gh-84461: Add --enable-wasm-pthreads to enable pthreads support for WASM builds. Emscripten/node no longer has threading enabled by default. Include additional file systems.

  • gh-91821: Fix unstable test_from_tuple test in test_decimal.py.

  • gh-91217: Deprecate the xdrlib module.

  • gh-91217: Deprecate the uu module.

  • gh-91760: More strict rules will be applied for numerical group references and group names in regular expressions. For now, a deprecation warning is emitted for group references and group names which will be errors in future Python versions.

  • gh-84461: Add provisional sys._emscripten_info named tuple with build-time and run-time information about Emscripten platform.

  • gh-90623: signal.raise_signal() and os.kill() now check immediately for pending signals. Patch by Victor Stinner.

  • gh-91734: Fix OSS audio support on Solaris.

  • gh-90633: Include the passed value in the exception thrown by typing.assert_never(). Patch by Jelle Zijlstra.

  • gh-91700: Compilation of regular expression containing a conditional expression (?(group)...) now raises an appropriate re.error if the group number refers to not defined group. Previously an internal RuntimeError was raised.

  • gh-91231: Add an optional keyword shutdown_timeout parameter to the multiprocessing.BaseManager constructor. Kill the process if terminate() takes longer than the timeout. Patch by Victor Stinner.

  • gh-91621: Fix typing.get_type_hints() for collections.abc.Callable. Patch by Shantanu Jain.

  • gh-90568: Parsing \N escapes of Unicode Named Character Sequences in a regular expression raises now re.error instead of TypeError.

  • gh-91670: Remove deprecated SO config variable in sysconfig.

  • gh-91217: Deprecate the telnetlib module.

  • gh-91217: Deprecate the sunau module.

  • gh-91217: Deprecate the spwd module.

  • gh-91217: Deprecate the sndhdr module, as well as inline needed functionality for email.mime.MIMEAudio.

  • gh-91616: re module, fix fullmatch() mismatch when using Atomic Grouping or Possessive Quantifiers.

  • gh-91217: Deprecate the ‘pipes’ module.

  • gh-91217: Deprecate the ossaudiodev module.

  • bpo-47256: re module, limit the maximum capturing group to 1,073,741,823 in 64-bit build, this increases the depth of backtracking.

  • gh-91217: Deprecate the nis module.

  • gh-91595: Fix the comparison of character and integer inside Tools.gdb.libpython.write_repr(). Patch by Yu Liu.

  • gh-74166: Add option to raise all errors from create_connection() in an ExceptionGroup when it fails to create a connection. The default remains to raise only the last error that had occurred when multiple addresses were tried.

  • gh-91487: Optimize asyncio UDP speed, over 100 times faster when transferring a large file.

  • gh-91575: Update case-insensitive matching in the re module to the latest Unicode version.

  • gh-90622: In concurrent.futures.process.ProcessPoolExecutor disallow the “fork” multiprocessing start method when the new max_tasks_per_child feature is used as the mix of threads+fork can hang the child processes. Default to using the safe “spawn” start method in that circumstance if no mp_context was supplied.

  • gh-89022: In sqlite3, SQLITE_MISUSE result codes are now mapped to InterfaceError instead of ProgrammingError. Also, more accurate exceptions are raised when binding parameters fail. Patch by Erlend E. Aasland.

  • gh-91526: Stop calling os.device_encoding(file.fileno()) in TextIOWrapper. It was complex, never documented, and didn’t work for most cases. (Patch by Inada Naoki.)

  • gh-88116: Change the frame-related functions in the inspect module to return a regular object (that is backwards compatible with the old tuple-like interface) that include the extended PEP 657 position information (end line number, column and end column). The affected functions are: inspect.getframeinfo(), inspect.getouterframes(), inspect.getinnerframes(), inspect.stack() and inspect.trace(). Patch by Pablo Galindo.

  • gh-69093: Add indexing and slicing support to sqlite3.Blob. Patch by Aviv Palivoda and Erlend E. Aasland.

  • gh-69093: Add context manager support to sqlite3.Blob. Patch by Aviv Palivoda and Erlend E. Aasland.

  • gh-91217: Deprecate nntplib.

  • gh-91217: Deprecate msilib.

  • gh-91404: Improve the performance of re matching by using computed gotos (or “threaded code”) on supported platforms and removing expensive pointer indirections.

  • gh-91217: Deprecate the imghdr module.

  • gh-91217: Deprecate the crypt module.

  • gh-91276: Make space for longer opcodes in dis output.

  • bpo-47000: Make TextIOWrapper uses locale encoding when encoding="locale" is specified even in UTF-8 mode.

  • gh-91230: warnings.catch_warnings() now accepts arguments for warnings.simplefilter(), providing a more concise way to locally ignore warnings or convert them to errors.

  • gh-91217: Deprecate the chunk module.

  • gh-91498: Add the TCP_CONNECTION_INFO option (available on macOS) to socket.

  • bpo-47260: Fix os.closerange() potentially being a no-op in a Linux seccomp sandbox.

  • bpo-47087: Implement typing.Required and typing.NotRequired (PEP 655). Patch by David Foster and Jelle Zijlstra.

  • bpo-47061: Deprecate cgi and cgitb.

  • bpo-47061: Deprecate audioop.

  • bpo-47000: Add locale.getencoding() to get the current locale encoding. It is similar to locale.getpreferredencoding(False) but ignores the Python UTF-8 Mode.

  • bpo-42012: Add wsgiref.types, containing WSGI-specific types for static type checking.

  • bpo-47227: Suppress expression chaining for more re parsing errors.

  • bpo-47211: Remove undocumented and never working function re.template() and flag re.TEMPLATE. This was later reverted in 3.11.0b2 and deprecated instead.

  • bpo-47135: decimal.localcontext() now accepts context attributes via keyword arguments

  • bpo-43323: Fix errors in the email module if the charset itself contains undecodable/unencodable characters.

  • bpo-46841: Disassembly of quickened code.

  • bpo-46681: Forward gzip.compress() compresslevel to zlib.

  • bpo-45100: Add typing.get_overloads() and typing.clear_overloads(). Patch by Jelle Zijlstra.

  • bpo-44807: typing.Protocol no longer silently replaces __init__() methods defined on subclasses. Patch by Adrian Garcia Badaracco.

  • bpo-46787: Fix concurrent.futures.ProcessPoolExecutor exception memory leak

  • bpo-46720: Add support for path-like objects to multiprocessing.set_executable() for Windows to be on a par with Unix-like systems. Patch by Géry Ogam.

  • bpo-46696: Add SO_INCOMING_CPU constant to socket.

  • bpo-46053: Fix OSS audio support on NetBSD.

  • bpo-45639: image/avif and image/webp were added to mimetypes.

  • bpo-46285: Add command-line option -p/--protocol to module http.server which specifies the HTTP version to which the server is conformant (HTTP/1.1 conformant servers can now be run from the command-line interface of module http.server). Patch by Géry Ogam.

  • bpo-44791: Accept ellipsis as the last argument of typing.Concatenate.

  • bpo-46547: Remove variables leaking into pydoc.Helper class namespace.

  • bpo-46415: Fix ipaddress.ip_{address,interface,network} raising TypeError instead of ValueError if given invalid tuple as address parameter.

  • bpo-46075: CookieJar with DefaultCookiePolicy now can process cookies from localhost with domain=localhost explicitly specified in Set-Cookie header.

  • bpo-45995: Add a “z” option to the string formatting specification that coerces negative zero floating-point values to positive zero after rounding to the format precision. Contributed by John Belmonte.

  • bpo-26175: Fully implement the io.BufferedIOBase or io.TextIOBase interface for tempfile.SpooledTemporaryFile objects. This lets them work correctly with higher-level layers (like compression modules). Patch by Carey Metcalfe.

  • bpo-45138: Fix a regression in the sqlite3 trace callback where bound parameters were not expanded in the passed statement string. The regression was introduced in Python 3.10 by bpo-40318. Patch by Erlend E. Aasland.

  • bpo-44863: Allow TypedDict subclasses to also include Generic as a base class in class based syntax. Thereby allowing the user to define a generic TypedDict, just like a user-defined generic but with TypedDict semantics.

  • bpo-44587: Fix BooleanOptionalAction to not automatically add a default string. If a default string is desired, use a formatter to add it.

  • bpo-43827: All positional-or-keyword parameters to ABCMeta.__new__ are now positional-only to avoid conflicts with keyword arguments to be passed to __init_subclass__().

  • bpo-43218: Prevent creation of a venv whose path contains the PATH separator. This could affect the usage of the activate script. Patch by Dustin Rodrigues.

  • bpo-38435: Add a process_group parameter to subprocess.Popen to help move more things off of the unsafe preexec_fn parameter.

  • bpo-42066: Fix cookies getting sorted in CookieJar.__iter__() which is an extra behavior and not mentioned in RFC 2965 or Netscape cookie protocol. Now the cookies in CookieJar follows the order of the Set-Cookie header. Patch by Iman Kermani.

  • bpo-40617: Add create_window_function() to sqlite3.Connection for creating aggregate window functions. Patch by Erlend E. Aasland.

  • bpo-40676: Convert csv to use Argument Clinic for csv.field_size_limit(), csv.get_dialect(), csv.unregister_dialect() and csv.list_dialects().

  • bpo-39716: Raise an ArgumentError when the same subparser name is added twice to an argparse.ArgumentParser. This is consistent with the (default) behavior when the same option string is added twice to an ArgumentParser.

  • bpo-36073: Raise ProgrammingError instead of segfaulting on recursive usage of cursors in sqlite3 converters. Patch by Sergey Fedoseev.

  • bpo-34975: Adds a start_tls() method to StreamWriter, which upgrades the connection with TLS using the given SSLContext.

  • bpo-22276: Path methods glob() and rglob() return only directories if pattern ends with a pathname components separator (/ or sep). Patch by Eisuke Kawashima.

  • bpo-24905: Add blobopen() to sqlite3.Connection. sqlite3.Blob allows incremental I/O operations on blobs. Patch by Aviv Palivoda and Erlend E. Aasland.

Documentation

Tests

  • gh-92169: Use warnings_helper.import_deprecated() to import deprecated modules uniformly in tests. Patch by Hugo van Kemenade.

  • gh-84461: When multiprocessing is enabled, libregrtest can now use a Python executable other than sys.executable via the --python flag.

  • gh-91904: Fix initialization of PYTHONREGRTEST_UNICODE_GUARD which prevented running regression tests on non-UTF-8 locale.

  • gh-91752: Added @requires_zlib to test.test_tools.test_freeze.TestFreeze.

  • gh-91607: Fix test_concurrent_futures to test the correct multiprocessing start method context in several cases where the test logic mixed this up.

  • bpo-40280: Threading tests are now skipped on WASM targets without pthread support.

  • bpo-47109: Test for ctypes.macholib.dyld, ctypes.macholib.dylib, and ctypes.macholib.framework are brought from manual pre-unittest times to ctypes.test location and structure. Patch by Oleg Iarygin.

  • bpo-29890: Add tests for ipaddress.IPv4Interface and ipaddress.IPv6Interface construction with tuple arguments. Original patch and tests by louisom.

Build

  • gh-89452: gdbm-compat is now preferred over ndbm if both are available on the system. This allows avoiding the problematic ndbm.h on macOS.

  • gh-91731: Python is now built with -std=c11 compiler option, rather than -std=c99. Patch by Victor Stinner.

  • bpo-47152: Add script and make target for generating sre_constants.h.

  • bpo-47103: Windows PGInstrument builds now copy a required DLL into the output directory, making it easier to run the profile stage of a PGO build.

Windows

  • bpo-46907: Update Windows installer to use SQLite 3.38.3.

  • bpo-47239: Fixed –list and –list-paths output for Python Launcher for Windows when used in an active virtual environment.

  • bpo-46907: Update Windows installer to use SQLite 3.38.2.

  • bpo-46785: Fix race condition between os.stat() and unlinking a file on Windows, by using errors codes returned by FindFirstFileW() when appropriate in win32_xstat_impl.

  • bpo-40859: Update Windows build to use xz-5.2.5

macOS

  • bpo-46907: Update macOS installer to SQLite 3.38.4.

Tools/Demos

  • gh-91583: Fix regression in the code generated by Argument Clinic for functions with the defining_class parameter.

  • gh-91575: Add script Tools/scripts/generate_re_casefix.py and the make target regen-re for generating additional data for case-insensitive matching according to the current Unicode version.

  • gh-91551: Remove the ancient Pynche color editor. It has moved to https://gitlab.com/warsaw/pynche

C API

Python 3.11.0 alpha 7

Release date: 2022-04-05

Core and Builtins

  • bpo-47212: Raise IndentationError instead of SyntaxError for a bare except with no following indent. Improve SyntaxError locations for an un-parenthesized generator used as arguments. Patch by Matthieu Dartiailh.

  • bpo-47186: Replace JUMP_IF_NOT_EG_MATCH by CHECK_EG_MATCH + jump.

  • bpo-47176: Emscripten builds cannot handle signals in the usual way due to platform limitations. Python can now handle signals. To use, set Module.Py_EmscriptenSignalBuffer to be a single byte SharedArrayBuffer and set Py_EMSCRIPTEN_SIGNAL_HANDLING to 1. Writing a number into the SharedArrayBuffer will cause the corresponding signal to be raised into the Python thread.

  • bpo-47186: Replace JUMP_IF_NOT_EXC_MATCH by CHECK_EXC_MATCH + jump.

  • bpo-47120: Replace the absolute jump opcode JUMP_NO_INTERRUPT by the relative JUMP_BACKWARD_NO_INTERRUPT.

  • bpo-46841: Avoid unnecessary allocations when comparing code objects.

  • bpo-47182: Fix a crash when using a named unicode character like "\N{digit nine}" after the main interpreter has been initialized a second time.

  • bpo-47162: WebAssembly cannot deal with bad function pointer casts (different count or types of arguments). Python can now use call trampolines to mitigate the problem. Define PY_CALL_TRAMPOLINE to enable call trampolines.

  • bpo-46775: Some Windows system error codes(>= 10000) are now mapped into the correct errno and may now raise a subclass of OSError. Patch by Donghee Na.

  • bpo-47129: Improve error messages in f-string syntax errors concerning empty expressions.

  • bpo-47117: Fix a crash if we fail to decode characters in interactive mode if the tokenizer buffers are uninitialized. Patch by Pablo Galindo.

  • bpo-47127: Speed up calls to c functions with keyword arguments by 25% with specialization. Patch by Kumar Aditya.

  • bpo-47120: Replaced JUMP_ABSOLUTE by the relative jump JUMP_BACKWARD.

  • bpo-42197: PyFrame_FastToLocalsWithError() and PyFrame_LocalsToFast() are no longer called during profiling nor tracing. C code can access the f_locals attribute of PyFrameObject by calling PyFrame_GetLocals().

  • bpo-47070: Improve performance of array_inplace_repeat by reducing the number of invocations of memcpy. Refactor the repeat and inplace repeat methods of array, bytes, bytearray and unicodeobject to use the common _PyBytes_Repeat.

  • bpo-47053: Reduce de-optimization in the specialized BINARY_OP_INPLACE_ADD_UNICODE opcode.

  • bpo-47045: Remove the f_state field from the _PyInterpreterFrame struct. Add the owner field to the _PyInterpreterFrame struct to make ownership explicit to simplify clearing and deallocing frames and generators.

  • bpo-46968: Check for the existence of the “sys/auxv.h” header in faulthandler to avoid compilation problems in systems where this header doesn’t exist. Patch by Pablo Galindo

  • bpo-46329: Use low bit of LOAD_GLOBAL to indicate whether to push a NULL before the global. Helps streamline the call sequence a bit.

  • bpo-46841: Quicken bytecode in-place by storing it as part of the corresponding PyCodeObject.

  • bpo-47012: Speed up iteration of bytes and bytearray by 30%. Patch by Kumar Aditya.

  • bpo-47009: Improved the performance of list.append() and list comprehensions by optimizing for the common case, where no resize is needed. Patch by Dennis Sweeney.

  • bpo-47005: Improve performance of bytearray_repeat and bytearray_irepeat by reducing the number of invocations of memcpy.

  • bpo-46829: Deprecate passing a message into asyncio.Future.cancel() and asyncio.Task.cancel()

  • bpo-46993: Speed up bytearray creation from list and tuple by 40%. Patch by Kumar Aditya.

  • bpo-39829: Removed the __len__() call when initializing a list and moved initializing to list_extend. Patch by Jeremiah Pascual.

  • bpo-46944: Speed up throwing exception in generator with METH_FASTCALL calling convention. Patch by Kumar Aditya.

  • bpo-46841: Modify STORE_SUBSCR to use an inline cache entry (rather than its oparg) as an adaptive counter.

  • bpo-46841: Use inline caching for PRECALL and CALL, and remove the internal machinery for managing the (now unused) non-inline caches.

  • bpo-46881: Statically allocate and initialize the latin1 characters.

  • bpo-46838: Improve syntax errors for incorrect function definitions. Patch by Pablo Galindo

  • bpo-43721: Fix docstrings of getter, setter, and deleter to clarify that they create a new copy of the property.

  • bpo-43224: Make grammar changes required for PEP 646.

Library

  • bpo-47208: Allow vendors to override CTYPES_MAX_ARGCOUNT.

  • bpo-23689: re module: fix memory leak when a match is terminated by a signal or memory allocation failure. Patch by Ma Lin.

  • bpo-47167: Allow overriding a future compliance check in asyncio.Task.

  • bpo-47151: When subprocess tries to use vfork, it now falls back to fork if vfork returns an error. This allows use in situations where vfork isn’t allowed by the OS kernel.

  • bpo-47152: Convert the re module into a package. Deprecate modules sre_compile, sre_constants and sre_parse.

  • bpo-4833: Add ZipFile.mkdir()

  • bpo-27929: Fix asyncio.loop.sock_connect() to only resolve names for socket.AF_INET or socket.AF_INET6 families. Resolution may not make sense for other families, like socket.AF_BLUETOOTH and socket.AF_UNIX.

  • bpo-14265: Adds the fully qualified test name to unittest output

  • bpo-47061: Deprecate the aifc module.

  • bpo-39622: Handle Ctrl+C in asyncio programs to interrupt the main task.

  • bpo-47101: hashlib.algorithms_available now lists only algorithms that are provided by activated crypto providers on OpenSSL 3.0. Legacy algorithms are not listed unless the legacy provider has been loaded into the default OSSL context.

  • bpo-47099: All URLError exception messages raised in urllib.request.URLopener now contain a colon between ftp error and the rest of the message. Previously, open_ftp() missed the colon. Patch by Oleg Iarygin.

  • bpo-47099: Exception chaining is changed from Exception.with_traceback()/sys.exc_info() to PEP 3134. Patch by Oleg Iarygin.

  • bpo-47095: hashlib’s internal _blake2 module now prefers libb2 from https://www.blake2.net/ over Python’s vendored copy of blake2.

  • bpo-47098: The Keccak Code Package for hashlib’s internal _sha3 module has been replaced with tiny_sha3. The module is used as fallback when Python is built without OpenSSL.

  • bpo-47088: Implement typing.LiteralString, part of PEP 675. Patch by Jelle Zijlstra.

  • bpo-42885: Optimize re.search(), re.split(), re.findall(), re.finditer() and re.sub() for regular expressions starting with \A or ^.

  • bpo-23691: Protect the re.finditer() iterator from re-entering.

  • bpo-47067: Optimize calling GenericAlias objects by using PEP 590 vectorcall and by replacing PyObject_SetAttrString with PyObject_SetAttr.

  • bpo-28080: Add the metadata_encoding parameter in the zipfile.ZipFile constructor and the --metadata-encoding option in the zipfile CLI to allow reading zipfiles using non-standard codecs to encode the filenames within the archive.

  • bpo-47000: Make io.text_encoding() returns “utf-8” when UTF-8 mode is enabled.

  • bpo-42369: Fix thread safety of zipfile._SharedFile.tell() to avoid a “zipfile.BadZipFile: Bad CRC-32 for file” exception when reading a ZipFile from multiple threads.

  • bpo-38256: Fix binascii.crc32() when it is compiled to use zlib’c crc32 to work properly on inputs 4+GiB in length instead of returning the wrong result. The workaround prior to this was to always feed the function data in increments smaller than 4GiB or to just call the zlib module function.

    We also have binascii.crc32() release the GIL when computing on larger inputs as zlib.crc32() and hashlib do.

    This also boosts performance on Windows as it now uses the zlib crc32 implementation for binascii.crc32() for a 2-3x speedup.

    That the stdlib has a crc32 API in two modules is a known historical oddity. This moves us closer to a single implementation behind them.

  • bpo-47066: Global inline flags (e.g. (?i)) can now only be used at the start of the regular expressions. Using them not at the start of expression was deprecated since Python 3.6.

  • bpo-39394: A warning about inline flags not at the start of the regular expression now contains the position of the flag.

  • bpo-433030: Add support of atomic grouping ((?>...)) and possessive quantifiers (*+, ++, ?+, {m,n}+) in regular expressions.

  • bpo-47062: Implement asyncio.Runner context manager.

  • bpo-46382: dataclass() slots=True now correctly omits slots already defined in base classes. Patch by Arie Bovenberg.

  • bpo-47057: Use FASTCALL convention for FutureIter.throw()

  • bpo-47061: Deprecate the various modules listed by PEP 594:

    aifc, asynchat, asyncore, audioop, cgi, cgitb, chunk, crypt, imghdr, msilib, nntplib, nis, ossaudiodev, pipes, smtpd, sndhdr, spwd, sunau, telnetlib, uu, xdrlib

  • bpo-34790: Remove passing coroutine objects to asyncio.wait().

  • bpo-47039: Normalize repr() of asyncio future and task objects.

  • bpo-2604: Fix bug where doctests using globals would fail when run multiple times.

  • bpo-45150: Add hashlib.file_digest() helper for efficient hashing of file object.

  • bpo-34861: Made cumtime the default sorting key for cProfile

  • bpo-45997: Fix asyncio.Semaphore re-aquiring FIFO order.

  • bpo-47022: The asynchat, asyncore and smtpd modules have been deprecated since at least Python 3.6. Their documentation and deprecation warnings and have now been updated to note they will removed in Python 3.12 (PEP 594).

  • bpo-43253: Fix a crash when closing transports where the underlying socket handle is already invalid on the Proactor event loop.

  • bpo-40280: select.select() now passes NULL to select for each empty fdset.

  • bpo-47004: Apply bugfixes from importlib_metadata 4.11.3, including bugfix for EntryPoint.extras, which was returning match objects and not the extras strings.

  • bpo-46998: Allow subclassing of typing.Any. Patch by Shantanu Jain.

  • bpo-46995: Deprecate missing asyncio.Task.set_name() for third-party task implementations, schedule making it mandatory in Python 3.13.

  • bpo-46994: Accept explicit contextvars.Context in asyncio.create_task() and asyncio.loop.create_task().

  • bpo-46981: typing.get_args(typing.Tuple[()]) now returns () instead of ((),).

  • bpo-46968: Add os.sysconf_names['SC_MINSIGSTKSZ'].

  • bpo-46985: Upgrade pip wheel bundled with ensurepip (pip 22.0.4)

  • bpo-46968: faulthandler: On Linux 5.14 and newer, dynamically determine size of signal handler stack size CPython allocates using getauxval(AT_MINSIGSTKSZ). This changes allows for Python extension’s request to Linux kernel to use AMX_TILE instruction set on Sapphire Rapids Xeon processor to succeed, unblocking use of the ISA in frameworks.

  • bpo-46917: The math.nan value is now always available. Patch by Victor Stinner.

  • bpo-46955: Expose asyncio.base_events.Server as asyncio.Server. Patch by Stefan Zabka.

  • bpo-23325: The signal module no longer assumes that SIG_IGN and SIG_DFL are small int singletons.

  • bpo-46932: Update bundled libexpat to 2.4.7

  • bpo-46933: The pwd module is now optional. os.path.expanduser() returns the path when the pwd module is not available.

  • bpo-40059: PEP 680, the tomllib module. Adds support for parsing TOML.

  • bpo-464471: asyncio.timeout() and asyncio.timeout_at() context managers added. Patch by Tin Tvrtković and Andrew Svetlov.

  • bpo-46805: Added raw datagram socket functions for asyncio: sock_sendto(), sock_recvfrom() and sock_recvfrom_into().

  • bpo-46644: No longer require valid typeforms to be callable. This allows typing.Annotated to wrap typing.ParamSpecArgs and dataclasses.InitVar. Patch by Gregory Beauregard.

  • bpo-46581: Brings ParamSpec propagation for GenericAlias in line with Concatenate (and others).

  • bpo-45413: Define posix_venv and nt_venv sysconfig installation schemes to be used for bootstrapping new virtual environments. Add venv sysconfig installation scheme to get the appropriate one of the above. The schemes are identical to the pre-existing posix_prefix and nt install schemes. The venv module now uses the venv scheme to create new virtual environments instead of hardcoding the paths depending only on the platform. Downstream Python distributors customizing the posix_prefix or nt install scheme in a way that is not compatible with the install scheme used in virtual environments are encouraged not to customize the venv schemes. When Python itself runs in a virtual environment, sysconfig.get_default_scheme() and sysconfig.get_preferred_scheme() with key="prefix" returns venv.

  • bpo-43224: Implement support for PEP 646 in typing.py.

  • bpo-43224: Allow unpacking types.GenericAlias objects, e.g. *tuple[int, str].

  • bpo-46557: Warnings captured by the logging module are now logged without a format string to prevent systems that group logs by the msg argument from grouping captured warnings together.

  • bpo-41370: typing.get_type_hints() now supports evaluating strings as forward references in PEP 585 generic aliases.

  • bpo-46607: Add DeprecationWarning to LegacyInterpolation, deprecated in the docstring since Python 3.2. Will be removed in Python 3.13. Use BasicInterpolation or ExtendedInterpolation instead.

  • bpo-26120: pydoc now excludes __future__ imports from the module’s data items.

  • bpo-46480: Add typing.assert_type(). Patch by Jelle Zijlstra.

  • bpo-46421: Fix a unittest issue where if the command was invoked as python -m unittest and the filename(s) began with a dot (.), a ValueError is returned.

  • bpo-46245: Add optional parameter dir_fd in shutil.rmtree().

  • bpo-22859: usageExit() is marked deprecated, to be removed in 3.13.

  • bpo-46170: Improve the error message when you try to subclass an instance of typing.NewType.

  • bpo-40296: Fix supporting generic aliases in pydoc.

  • bpo-20392: Fix inconsistency with uppercase file extensions in MimeTypes.guess_type(). Patch by Kumar Aditya.

  • bpo-46030: Add LOCAL_CREDS, LOCAL_CREDS_PERSISTENT and SCM_CREDS2 FreeBSD constants to the socket module.

  • bpo-44439: Fix .write() method of a member file in ZipFile, when the input data is an object that supports the buffer protocol, the file length may be wrong.

  • bpo-45171: Fix handling of the stacklevel argument to logging functions in the logging module so that it is consistent across all logging functions and, as advertised, similar to the stacklevel argument used in warn().

  • bpo-24959: Fix bug where unittest sometimes drops frames from tracebacks of exceptions raised in tests.

  • bpo-44859: Raise more accurate and PEP 249 compatible exceptions in sqlite3.

  • bpo-44493: Add missing terminated NUL in sockaddr_un’s length

    This was potentially observable when using non-abstract AF_UNIX datagram sockets to processes written in another programming language.

  • bpo-41930: Add serialize() and deserialize() support to sqlite3. Patch by Erlend E. Aasland.

  • bpo-33178: Added ctypes.BigEndianUnion and ctypes.LittleEndianUnion classes, as originally documented in the library docs but not yet implemented.

  • bpo-43352: Add an Barrier object in synchronization primitives of asyncio Lib in order to be consistant with Barrier from threading and multiprocessing libs*

  • bpo-35859: re module, fix a few bugs about capturing group. In rare cases, capturing group gets an incorrect string. Patch by Ma Lin.

Documentation

Tests

Build

  • bpo-40280: Add configure option --enable-wasm-dynamic-linking to enable dlopen and MAIN_MODULE / SIDE_MODULE on wasm32-emscripten.

  • bpo-46023: makesetup now detects and skips all duplicated module definitions. The first entry wins.

  • bpo-40280: Add SOABI wasm32-emscripten for Emscripten and wasm32-wasi for WASI on 32bit WASM as well as wasm64 counter parts.

  • bpo-47032: Ensure Windows install builds fail correctly with a non-zero exit code when part of the build fails.

  • bpo-47024: Update OpenSSL to 1.1.1n for macOS installers and all Windows builds.

  • bpo-46996: The tkinter package now requires Tcl/Tk version 8.5.12 or newer.

  • bpo-46973: Add regen-configure make target to regenerate configure script with Christian’s container image quay.io/tiran/cpython_autoconf:269.

  • bpo-46917: Building Python now requires support of IEEE 754 floating point numbers. Patch by Victor Stinner.

  • bpo-45774: configure now verifies that all SQLite C APIs needed for the sqlite3 extension module are found.

Windows

  • bpo-47194: Update zlib to v1.2.12 to resolve CVE-2018-25032.

  • bpo-47171: Enables installing the py.exe launcher on Windows ARM64.

  • bpo-46566: Upgraded Python Launcher for Windows to support a new -V:company/tag argument for full PEP 514 support and to detect ARM64 installs. The -64 suffix on arguments is deprecated, but still selects any non-32-bit install. Setting PYLAUNCHER_ALLOW_INSTALL and specifying a version that is not installed will attempt to install the requested version from the Microsoft Store.

  • bpo-47086: The installer for Windows now includes documentation as loose HTML files rather than a single compiled .chm file.

  • bpo-46907: Update Windows installer to use SQLite 3.38.1.

  • bpo-44549: Update bzip2 to 1.0.8 in Windows builds to mitigate CVE-2016-3189 and CVE-2019-12900

  • bpo-46948: Prevent CVE-2022-26488 by ensuring the Add to PATH option in the Windows installer uses the correct path when being repaired.

macOS

  • bpo-46890: Fix a regression in the setting of sys._base_executable in framework builds, and thereby fix a regression in venv virtual environments with such builds.

  • bpo-46907: Update macOS installer to SQLite 3.38.1.

Tools/Demos

  • bpo-40280: Replace Emscripten’s limited shell with Katie Bell’s browser-ui REPL from python-wasm project.

C API

  • bpo-40421: Add PyFrame_GetBuiltins, PyFrame_GetGenerator and PyFrame_GetGlobals C-API functions to access frame object attributes safely from C code.

  • bpo-46850: Move the private _PyFrameEvalFunction type, and private _PyInterpreterState_GetEvalFrameFunc() and _PyInterpreterState_SetEvalFrameFunc() functions to the internal C API. The _PyFrameEvalFunction callback function type now uses the _PyInterpreterFrame type which is part of the internal C API. Patch by Victor Stinner.

  • bpo-46850: Move the private undocumented _PyEval_EvalFrameDefault() function to the internal C API. The function now uses the _PyInterpreterFrame type which is part of the internal C API. Patch by Victor Stinner.

  • bpo-46850: Remove the private undocumented function _PyEval_CallTracing() from the C API. Call the public sys.call_tracing() function instead. Patch by Victor Stinner.

  • bpo-46850: Remove the private undocumented function _PyEval_GetCoroutineOriginTrackingDepth() from the C API. Call the public sys.get_coroutine_origin_tracking_depth() function instead. Patch by Victor Stinner.

  • bpo-46850: Remove the following private undocumented functions from the C API:

    • _PyEval_GetAsyncGenFirstiter()

    • _PyEval_GetAsyncGenFinalizer()

    • _PyEval_SetAsyncGenFirstiter()

    • _PyEval_SetAsyncGenFinalizer()

    Call the public sys.get_asyncgen_hooks() and sys.set_asyncgen_hooks() functions instead. Patch by Victor Stinner.

  • bpo-46987: Remove private functions _PySys_GetObjectId() and _PySys_SetObjectId(). Patch by Donghee Na.

  • bpo-46906: Add new functions to pack and unpack C double (serialize and deserialize): PyFloat_Pack2(), PyFloat_Pack4(), PyFloat_Pack8(), PyFloat_Unpack2(), PyFloat_Unpack4() and PyFloat_Unpack8(). Patch by Victor Stinner.

Python 3.11.0 alpha 6

Release date: 2022-03-07

Core and Builtins

  • bpo-46940: Avoid overriding AttributeError metadata information for nested attribute access calls. Patch by Pablo Galindo.

  • bpo-46927: Include the type’s name in the error message for subscripting non-generic types.

  • bpo-46921: Support vectorcall for super(). Patch by Ken Jin.

  • bpo-46841: Fix incorrect handling of inline cache entries when specializing BINARY_OP.

  • bpo-46841: Use an oparg to simplify the construction of helpful error messages in GET_AWAITABLE.

  • bpo-46903: Make sure that str subclasses can be used as attribute names for instances with virtual dictionaries. Fixes regression in 3.11alpha

  • bpo-46841: Add more detailed specialization failure stats for COMPARE_OP followed by EXTENDED_ARG.

  • bpo-46891: Fix bug introduced during 3.11alpha where subclasses of types.ModuleType with __slots__ were not initialized correctly, resulting in an interpreter crash.

  • bpo-46841: Use inline caching for LOAD_ATTR, LOAD_METHOD, and STORE_ATTR.

  • bpo-46841: Use inline cache for BINARY_SUBSCR.

  • bpo-46841: Use inline caching for COMPARE_OP.

  • bpo-46864: Deprecate PyBytesObject.ob_shash. It will be removed in Python 3.13.

  • bpo-46841: Use inline caching for UNPACK_SEQUENCE.

  • bpo-46845: Reduces dict size by removing hash value from hash table when all inserted keys are Unicode. For example, sys.getsizeof(dict.fromkeys("abcdefg")) becomes 272 bytes from 352 bytes on 64bit platform.

  • bpo-46841: Use inline cache for LOAD_GLOBAL.

  • bpo-46852: Rename the private undocumented float.__set_format__() method to float.__setformat__() to fix a typo introduced in Python 3.7. The method is only used by test_float. Patch by Victor Stinner.

  • bpo-46852: Remove the undocumented private float.__set_format__() method, previously known as float.__setformat__() in Python 3.7. Its docstring said: “You probably don’t want to use this function. It exists mainly to be used in Python’s test suite.” Patch by Victor Stinner.

  • bpo-40116: Fix regression that dict.update(other) may don’t respect iterate order of other when other is key sharing dict.

  • bpo-46712: Share global string identifiers in deep-frozen modules.

  • bpo-46430: Fix memory leak in interned strings of deep-frozen modules.

  • bpo-46841: Store BINARY_OP caches inline using a new CACHE instruction.

  • bpo-45107: Specialize LOAD_METHOD for instances with a dict.

  • bpo-44337: Reduce the memory usage of specialized LOAD_ATTR and STORE_ATTR instructions.

  • bpo-46729: Add number of sub-exceptions to BaseException.__str__().

  • bpo-45885: Don’t un-adapt COMPARE_OP when collecting specialization stats.

  • bpo-46329: Fix specialization stats gathering for PRECALL instructions.

  • bpo-46794: Bump up the libexpat version into 2.4.6

  • bpo-46823: Implement a specialized combined opcode LOAD_FAST__LOAD_ATTR_INSTANCE_VALUE. Patch by Dennis Sweeney.

  • bpo-46820: Fix parsing a numeric literal immediately (without spaces) followed by “not in” keywords, like in 1not in x. Now the parser only emits a warning, not a syntax error.

  • bpo-46329: Move KW_NAMES before PRECALL instruction in call sequence. Change operand of CALL to match PRECALL for easier specialization.

  • bpo-46808: Remove the NEXT_BLOCK macro from compile.c, and make the compiler automatically generate implicit blocks when they are needed.

  • bpo-46329: Add PUSH_NULL instruction. This is used as a prefix when evaluating a callable, so that the stack has the same shape for methods and other calls. PRECALL_FUNCTION and PRECALL_METHOD are merged into a single PRECALL instruction.

    There is no change in semantics.

  • bpo-46762: Fix an assert failure in debug builds when a ‘<’, ‘>’, or ‘=’ is the last character in an f-string that’s missing a closing right brace.

  • bpo-46730: Message of AttributeError caused by getting, setting or deleting a property without the corresponding function now mentions that the attribute is in fact a property and also specifies type of the class that it belongs to.

  • bpo-46724: Make sure that all backwards jumps use the JUMP_ABSOLUTE instruction, rather than JUMP_FORWARD with an argument of (2**32)+offset.

  • bpo-46732: Correct the docstring for the __bool__() method. Patch by Jelle Zijlstra.

  • bpo-46072: Add more detailed specialization failure statistics for BINARY_OP.

  • bpo-46707: Avoid potential exponential backtracking when producing some syntax errors involving lots of brackets. Patch by Pablo Galindo.

  • bpo-46323: ctypes now allocates memory on the stack instead of on the heap to pass arguments while calling a Python callback function. Patch by Donghee Na.

  • bpo-45923: Add a quickened form of RESUME that skips quickening checks.

  • bpo-46702: Specialize UNPACK_SEQUENCE for tuple and list unpackings.

  • bpo-46072: Opcode pair stats are now gathered with --enable-pystats. Defining DYNAMIC_EXECUTION_PROFILE or DXPAIRS no longer has any effect.

  • bpo-46675: Allow more than 16 items in a split dict before it is combined. The limit is now 254.

  • bpo-40479: Add a missing call to va_end() in Modules/_hashopenssl.c.

  • bpo-46323: Use PyObject_Vectorcall() while calling ctypes callback function. Patch by Donghee Na.

  • bpo-46615: When iterating over sets internally in setobject.c, acquire strong references to the resulting items from the set. This prevents crashes in corner-cases of various set operations where the set gets mutated.

  • bpo-45828: The bytecode compiler now attempts to apply runtime stack manipulations at compile-time (whenever it is feasible to do so).

  • bpo-30496: Fixed a minor portability issue in the implementation of PyLong_FromLong(), and added a fast path for single-digit integers to PyLong_FromLongLong().

Library

Documentation

  • bpo-42238: Doc/tools/rstlint.py has moved to its own repository and is now packaged on PyPI as sphinx-lint.

Tests

  • bpo-46913: Fix test_faulthandler.test_sigfpe() if Python is built with undefined behavior sanitizer (UBSAN): disable UBSAN on the faulthandler_sigfpe() function. Patch by Victor Stinner.

  • bpo-46760: Remove bytecode offsets from expected values in test.test_dis module. Reduces the obstacles to modifying the VM or compiler.

  • bpo-46708: Prevent default asyncio event loop policy modification warning after test_asyncio execution.

  • bpo-46678: The function make_legacy_pyc in Lib/test/support/import_helper.py no longer fails when PYTHONPYCACHEPREFIX is set to a directory on a different device from where tempfiles are stored.

  • bpo-46623: Skip test_pair() and test_speech128() of test_zlib on s390x since they fail if zlib uses the s390x hardware accelerator. Patch by Victor Stinner.

Build

  • bpo-46860: Respect --with-suffix when building on case-insensitive file systems.

  • bpo-46656: Building Python now requires a C11 compiler. Optional C11 features are not required. Patch by Victor Stinner.

  • bpo-46656: Building Python now requires support for floating point Not-a-Number (NaN): remove the Py_NO_NAN macro. Patch by Victor Stinner.

  • bpo-46640: Building Python now requires a C99 <math.h> header file providing a NAN constant, or the __builtin_nan() built-in function. Patch by Victor Stinner.

  • bpo-46608: Exclude marshalled-frozen data if deep-freezing to save 300 KB disk space. This includes adding a new is_package field to _frozen. Patch by Kumar Aditya.

  • bpo-40280: Fix wasm32-emscripten test failures and platform issues. - Disable syscalls that are not supported or don’t work, e.g. wait, getrusage, prlimit, mkfifo, mknod, setres[gu]id, setgroups. - Use fd_count to cound open fds. - Add more checks for subprocess and fork. - Add workarounds for missing _multiprocessing and failing socket.accept(). - Enable bzip2. - Disable large file support. - Disable signal.alarm.

  • bpo-46430: Intern strings in deep-frozen modules. Patch by Kumar Aditya.

Windows

  • bpo-46744: The default all users install directory for ARM64 is now under the native Program Files folder, rather than Program Files (Arm) which is intended for ARM (32-bit) files.

  • bpo-46567: Adds Tcl and Tk support for Windows ARM64. This also adds IDLE to the installation.

  • bpo-46638: Ensures registry virtualization is consistently disabled. For 3.10 and earlier, it remains enabled (some registry writes are protected), while for 3.11 and later it is disabled (registry modifications affect all applications).

IDLE

  • bpo-46630: Make query dialogs on Windows start with a cursor in the entry box.

  • bpo-45447: Apply IDLE syntax highlighting to .pyi files. Patch by Alex Waygood and Terry Jan Reedy.

C API

  • bpo-46748: Python’s public headers no longer import <stdbool.h>, leaving code that embedd/extends Python free to define bool, true and false.

  • bpo-46836: Move the PyFrameObject type definition (struct _frame) to the internal C API pycore_frame.h header file. Patch by Victor Stinner.

  • bpo-45459: Rename Include/buffer.h header file to Include/pybuffer.h to avoid conflits with projects having an existing buffer.h header file. Patch by Victor Stinner.

  • bpo-45412: Remove the HAVE_PY_SET_53BIT_PRECISION macro (moved to the internal C API). Patch by Victor Stinner.

  • bpo-46613: Added function PyType_GetModuleByDef(), which allows accesss to module state when a method’s defining class is not available.

Python 3.11.0 alpha 5

Release date: 2022-02-03

Core and Builtins

  • bpo-45773: Remove two invalid “peephole” optimizations from the bytecode compiler.

  • bpo-46564: Do not create frame objects when creating super object. Patch by Kumar Aditya.

  • bpo-45885: Added more fined-grained specialization failure stats regarding the COMPARE_OP bytecode.

  • bpo-44977: The delegation of int() to __trunc__() is now deprecated. Calling int(a) when type(a) implements __trunc__() but not __int__() or __index__() now raises a DeprecationWarning.

  • bpo-46458: Reorder code emitted by the compiler for a try-except block so that the else block’s code immediately follows the try body (without a jump). This is more optimal for the happy path.

  • bpo-46527: Allow passing iterable as a keyword argument to enumerate() again. Patch by Jelle Zijlstra.

  • bpo-46528: Replace several stack manipulation instructions (DUP_TOP, DUP_TOP_TWO, ROT_TWO, ROT_THREE, ROT_FOUR, and ROT_N) with new COPY and SWAP instructions.

  • bpo-46329: Use two or three bytecodes to implement most calls.

    Calls without named arguments are implemented as a sequence of two instructions: PRECALL; CALL. Calls with named arguments are implemented as a sequence of three instructions: PRECALL; KW_NAMES; CALL. There are two different PRECALL instructions: PRECALL_FUNTION and PRECALL_METHOD. The latter pairs with LOAD_METHOD.

    This partition into pre-call and call allows better specialization, and thus better performance ultimately.

    There is no change in semantics.

  • bpo-46503: Fix an assert when parsing some invalid N escape sequences in f-strings.

  • bpo-46431: Improve error message on invalid calls to BaseExceptionGroup.__new__().

  • bpo-46476: Fix memory leak in code objects generated by deepfreeze. Patch by Kumar Aditya.

  • bpo-46481: Speed up calls to weakref.ref.__call__() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-46417: Fix a race condition on setting a type __bases__ attribute: the internal function add_subclass() now gets the PyTypeObject.tp_subclasses member after calling PyWeakref_NewRef() which can trigger a garbage collection which can indirectly modify PyTypeObject.tp_subclasses. Patch by Victor Stinner.

  • bpo-46417: python -X showrefcount now shows the total reference count after clearing and destroyed the main Python interpreter. Previously, it was shown before. Patch by Victor Stinner.

  • bpo-43683: Add ASYNC_GEN_WRAP opcode to wrap the value to be yielded in async generators. Removes the need to special case async generators in the YIELD_VALUE instruction.

  • bpo-46407: Optimize some modulo operations in Objects/longobject.c. Patch by Jeremiah Vivian.

  • bpo-46409: Add new RETURN_GENERATOR bytecode to make generators. Simplifies calling Python functions in the VM, as they no longer any need to special case generator functions.

    Also add JUMP_NO_INTERRUPT bytecode that acts like JUMP_ABSOLUTE, but does not check for interrupts.

  • bpo-46406: The integer division // implementation has been optimized to better let the compiler understand its constraints. It can be 20% faster on the amd64 platform when dividing an int by a value smaller than 2**30.

  • bpo-46383: Fix invalid signature of _zoneinfo’s module_free function to resolve a crash on wasm32-emscripten platform.

  • bpo-46361: Ensure that “small” integers created by int.from_bytes() and decimal.Decimal are properly cached.

  • bpo-46161: Fix the class building error when the arguments are constants and CALL_FUNCTION_EX is used.

  • bpo-46028: Fixes calculation of sys._base_executable when inside a virtual environment that uses symlinks with different binary names than the base environment provides.

  • bpo-46091: Correctly calculate indentation levels for lines with whitespace character that are ended by line continuation characters. Patch by Pablo Galindo

  • bpo-30512: Add CAN Socket support for NetBSD.

  • bpo-46045: Do not use POSIX semaphores on NetBSD

  • bpo-44024: Improve the TypeError message for non-string second arguments passed to the built-in functions getattr() and hasattr(). Patch by Géry Ogam.

Library

  • bpo-46624: Restore support for non-integer arguments of random.randrange() and random.randint().

  • bpo-46591: Make the IDLE doc URL on the About IDLE dialog clickable.

  • bpo-46565: Remove loop variables that are leaking into modules’ namespaces.

  • bpo-46553: In typing.get_type_hints(), support evaluating bare stringified ClassVar annotations. Patch by Gregory Beauregard.

  • bpo-46544: Don’t leak x & uspace intermediate vars in textwrap.TextWrapper.

  • bpo-46487: Add the get_write_buffer_limits method to asyncio.transports.WriteTransport and to the SSL transport.

  • bpo-45173: Note the configparser deprecations will be removed in Python 3.12.

  • bpo-45162: The deprecated unittest APIs removed in 3.11a1 have been temporarily restored to be removed in 3.12 while cleanups in external projects go in.

  • bpo-46539: In typing.get_type_hints(), support evaluating stringified ClassVar and Final annotations inside Annotated. Patch by Gregory Beauregard.

  • bpo-46510: Add missing test for types.TracebackType and types.FrameType. Calculate them directly from the caught exception without calling sys.exc_info().

  • bpo-46491: Allow typing.Annotated to wrap typing.Final and typing.ClassVar. Patch by Gregory Beauregard.

  • bpo-46483: Remove __class_getitem__() from pathlib.PurePath as this class was not supposed to be generic.

  • bpo-46436: Fix command-line option -d/--directory in module http.server which is ignored when combined with command-line option --cgi. Patch by Géry Ogam.

  • bpo-41403: Make mock.patch() raise a TypeError with a relevant error message on invalid arg. Previously it allowed a cryptic AttributeError to escape.

  • bpo-46474: In importlib.metadata.EntryPoint.pattern, avoid potential REDoS by limiting ambiguity in consecutive whitespace.

  • bpo-46474: Removed private method from importlib.metadata.Path. Sync with importlib_metadata 4.10.0.

  • bpo-46470: Remove unused branch from typing._remove_dups_flatten

  • bpo-46469: asyncio generic classes now return types.GenericAlias in __class_getitem__ instead of the same class.

  • bpo-41906: Support passing filter instances in the filters values of handlers and loggers in the dictionary passed to logging.config.dictConfig().

  • bpo-46422: Use dis.Positions in dis.Instruction instead of a regular tuple.

  • bpo-46434: pdb now gracefully handles help when __doc__ is missing, for example when run with pregenerated optimized .pyc files.

  • bpo-43869: Python uses the same time Epoch on all platforms. Add an explicit unit test to ensure that it’s the case. Patch by Victor Stinner.

  • bpo-46414: Add typing.reveal_type(). Patch by Jelle Zijlstra.

  • bpo-40280: subprocess now imports Windows-specific imports when msvcrt module is available, and POSIX-specific imports on all other platforms. This gives a clean exception when _posixsubprocess is not available (e.g. Emscripten browser target).

  • bpo-40066: IntEnum, IntFlag, and StrEnum use the mixed-in type for their str() and format() output.

  • bpo-46316: Optimize pathlib.Path.iterdir() by removing an unnecessary check for special entries.

  • bpo-29688: Document pathlib.Path.absolute() (which has always existed).

  • bpo-43012: The pathlib module’s obsolete and internal _Accessor class has been removed to prepare the terrain for upcoming enhancements to the module.

  • bpo-46258: Speed up math.isqrt() for small positive integers by replacing two division steps with a lookup table.

  • bpo-46242: Improve error message when creating a new enum.Enum type subclassing an existing Enum with _member_names_ using enum.Enum.__call__().

  • bpo-43118: Fix a bug in inspect.signature() that was causing it to fail on some subclasses of classes with a __text_signature__ referencing module globals. Patch by Weipeng Hong.

  • bpo-26552: Fixed case where failing asyncio.ensure_future() did not close the coroutine. Patch by Kumar Aditya.

  • bpo-21987: Fix an issue with tarfile.TarFile.getmember() getting a directory name with a trailing slash.

  • bpo-46124: Update zoneinfo to rely on importlib.resources traversable API.

  • bpo-46103: Now inspect.getmembers() only gets __bases__ attribute from class type. Patch by Weipeng Hong.

  • bpo-46080: Fix exception in argparse help text generation if a argparse.BooleanOptionalAction argument’s default is argparse.SUPPRESS and it has help specified. Patch by Felix Fontein.

  • bpo-44791: Fix substitution of ParamSpec in Concatenate with different parameter expressions. Substitution with a list of types returns now a tuple of types. Substitution with Concatenate returns now a Concatenate with concatenated lists of arguments.

Documentation

  • bpo-46463: Fixes escape4chm.py script used when building the CHM documentation file

Tests

  • bpo-43478: Mocks can no longer be provided as the specs for other Mocks. As a result, an already-mocked object cannot be passed to mock.Mock(). This can uncover bugs in tests since these Mock-derived Mocks will always pass certain tests (e.g. isinstance) and builtin assert functions (e.g. assert_called_once_with) will unconditionally pass.

  • bpo-46616: Ensures test_importlib.test_windows cleans up registry keys after completion.

  • bpo-44359: test_ftplib now silently ignores socket errors to prevent logging unhandled threading exceptions. Patch by Victor Stinner.

  • bpo-46600: Fix test_gdb.test_pycfunction() for Python built with clang -Og. Tolerate inlined functions in the gdb traceback. Patch by Victor Stinner.

  • bpo-46542: Fix a Python crash in test_lib2to3 when using Python built in debug mode: limit the recursion limit. Patch by Victor Stinner.

  • bpo-46576: test_peg_generator now disables compiler optimization when testing compilation of its own C extensions to significantly speed up the testing on non-debug builds of CPython.

  • bpo-46542: Fix test_json tests checking for RecursionError: modify these tests to use support.infinite_recursion(). Patch by Victor Stinner.

  • bpo-13886: Skip test_builtin PTY tests on non-ASCII characters if the readline module is loaded. The readline module changes input() behavior, but test_builtin is not intented to test the readline module. Patch by Victor Stinner.

  • bpo-40280: Add test.support.requires_fork() decorators to mark tests that require a working os.fork().

  • bpo-40280: Add test.support.requires_subprocess() decorator to mark tests which require working subprocess module or os.spawn*. The wasm32-emscripten platform has no support for processes.

  • bpo-46126: Disable ‘descriptions’ when running tests internally.

Build

  • bpo-46602: Tidied up configure.ac so that conftest.c is truncated rather than appended. This assists in the case where the ‘rm’ of conftest.c fails to happen between tests. Downstream issues such as a clobbered SOABI can result.

  • bpo-46600: Fix the test checking if the C compiler supports -Og option in the ./configure script to also use -Og on clang which supports it. Patch by Victor Stinner.

  • bpo-38472: Fix GCC detection in setup.py when cross-compiling. The C compiler is now run with LC_ALL=C. Previously, the detection failed with a German locale.

  • bpo-46513: configure no longer uses AC_C_CHAR_UNSIGNED macro and pyconfig.h no longer defines reserved symbol __CHAR_UNSIGNED__.

  • bpo-46471: Use global singletons for single byte bytes objects in deepfreeze.

  • bpo-46443: Deepfreeze now uses cached small integers as it saves some space for common small integers.

  • bpo-46429: Merge all deep-frozen files into one for space savings. Patch by Kumar Aditya.

  • bpo-45569: The build now defaults to using 30-bit digits for Python integers. Previously either 15-bit or 30-bit digits would be selected, depending on the platform. 15-bit digits may still be selected using the --enable-big-digits=15 option to the configure script, or by defining PYLONG_BITS_IN_DIGIT in pyconfig.h.

  • bpo-45925: Update Windows installer to use SQLite 3.37.2.

  • bpo-43112: Detect musl libc as a separate SOABI (tagged as linux-musl).

Windows

  • bpo-33125: The traditional EXE/MSI based installer for Windows is now available for ARM64

  • bpo-46362: os.path.abspath(“C:CON”) is now fixed to return “\.CON”, not the same path. The regression was true of all legacy DOS devices such as COM1, LPT1, or NUL.

  • bpo-44934: The installer now offers a command-line only option to add the installation directory to the end of PATH instead of at the start.

macOS

  • bpo-45925: Update macOS installer to SQLite 3.37.2.

IDLE

  • bpo-45296: Clarify close, quit, and exit in IDLE. In the File menu, ‘Close’ and ‘Exit’ are now ‘Close Window’ (the current one) and ‘Exit’ is now ‘Exit IDLE’ (by closing all windows). In Shell, ‘quit()’ and ‘exit()’ mean ‘close Shell’. If there are no other windows, this also exits IDLE.

C API

  • bpo-40170: Remove the PyHeapType_GET_MEMBERS() macro. It was exposed in the public C API by mistake, it must only be used by Python internally. Use the PyTypeObject.tp_members member instead. Patch by Victor Stinner.

  • bpo-40170: Move _Py_GetAllocatedBlocks() and _PyObject_DebugMallocStats() private functions to the internal C API. Patch by Victor Stinner.

  • bpo-46433: The internal function _PyType_GetModuleByDef now correctly handles inheritance patterns involving static types.

  • bpo-45459: Py_buffer and various Py_buffer related functions are now part of the limited API and stable ABI.

  • bpo-14916: Fixed bug in the tokenizer that prevented PyRun_InteractiveOne from parsing from the provided FD.

Python 3.11.0 alpha 4

Release date: 2022-01-13

Core and Builtins

  • bpo-46070: Py_EndInterpreter() now explicitly untracks all objects currently tracked by the GC. Previously, if an object was used later by another interpreter, calling PyObject_GC_UnTrack() on the object crashed if the previous or the next object of the PyGC_Head structure became a dangling pointer. Patch by Victor Stinner.

  • bpo-46347: Fix memory leak in PyEval_EvalCodeEx.

  • bpo-46339: Fix a crash in the parser when retrieving the error text for multi-line f-strings expressions that do not start in the first line of the string. Patch by Pablo Galindo

  • bpo-46331: Do not set line number of instruction storing doc-string. Fixes regression introduced in 3.11 alpha.

  • bpo-46314: Remove spurious “call” event when creating a lambda function that was accidentally introduced in 3.11a4.

  • bpo-46289: ASDL declaration of FormattedValue has changed to reflect conversion field is not optional.

  • bpo-46297: Fixed an interpreter crash on bootup with multiple PythonPaths set in the Windows registry. Patch by Derzsi Dániel.

  • bpo-46237: Fix the line number of tokenizer errors inside f-strings. Patch by Pablo Galindo.

  • bpo-46263: We always expect the “use_frozen_modules” config to be set, now that getpath.c was rewritten in pure Python and the logic improved.

  • bpo-46006: Fix a regression when a type method like __init__() is modified in a subinterpreter. Fix a regression in _PyUnicode_EqualToASCIIId() and type update_slot(). Revert the change which made the Unicode dictionary of interned strings compatible with subinterpreters: the internal interned dictionary is shared again by all interpreters. Patch by Victor Stinner.

  • bpo-45923: Add RESUME opcode. This is a logical no-op. It is emitted by the compiler anywhere a Python function can be entered. It is used by the interpreter to perform tracing and optimizer checks.

  • bpo-46208: Fix the regression of os.path.normpath(“A/../../B”) not returning expected “../B” but “B”.

  • bpo-46240: Correct the error message for unclosed parentheses when the tokenizer doesn’t reach the end of the source when the error is reported. Patch by Pablo Galindo

  • bpo-46009: Remove the GEN_START opcode.

  • bpo-46235: Certain sequence multiplication operations like [0] * 1_000 are now faster due to reference-counting optimizations. Patch by Dennis Sweeney.

  • bpo-46221: PREP_RERAISE_STAR no longer pushes lasti to the stack.

  • bpo-46202: Remove POP_EXCEPT_AND_RERAISE and replace it by an equivalent sequence of other opcodes.

  • bpo-46085: Fix iterator cache mechanism of OrderedDict.

  • bpo-46055: Speed up shifting operation involving integers less than PyLong_BASE. Patch by Xinhang Xu.

  • bpo-46110: Add a maximum recursion check to the PEG parser to avoid stack overflow. Patch by Pablo Galindo

  • bpo-46107: Fix bug where ExceptionGroup.split() and ExceptionGroup.subgroup() did not copy the exception group’s __note__ field to the parts.

  • bpo-45711: The interpreter state’s representation of handled exceptions (a.k.a exc_info, or _PyErr_StackItem) now has only the exc_value field, exc_type and exc_traceback have been removed as their values can be derived from exc_value.

  • bpo-44525: Replace the four call bytecode instructions which one pre-call instruction and two call instructions.

    Removes CALL_FUNCTION, CALL_FUNCTION_KW, CALL_METHOD and CALL_METHOD_KW.

    Adds CALL_NO_KW and CALL_KW call instructions, and PRECALL_METHOD prefix for pairing with LOAD_METHOD.

  • bpo-46039: Remove the YIELD_FROM instruction and replace it with the SEND instruction which performs the same operation, but without the loop.

  • bpo-45635: The code called from _PyErr_Display() was refactored to improve error handling. It now exits immediately upon an unrecoverable error.

  • bpo-46054: Fix parser error when parsing non-utf8 characters in source files. Patch by Pablo Galindo.

  • bpo-46042: Improve the location of the caret in SyntaxError exceptions emitted by the symbol table. Patch by Pablo Galindo.

  • bpo-46049: Ensure ._pth files work as intended on platforms other than Windows.

  • bpo-46048: Fixes parsing of ._pth files on startup so that single-character paths are correctly read.

  • bpo-37971: Fix a bug where the line numbers given in a traceback when a decorator application raised an exception were wrong.

  • bpo-46031: Add POP_JUMP_IF_NOT_NONE and POP_JUMP_IF_NONE opcodes to speed up conditional jumps.

  • bpo-45654: Deepfreeze runpy, patch by Kumar Aditya.

  • bpo-46025: Fix a crash in the atexit module involving functions that unregister themselves before raising exceptions. Patch by Pablo Galindo.

  • bpo-46000: Improve compatibility of the curses module with NetBSD curses.

  • bpo-44525: Specialize the CALL_FUNCTION instruction for calls to builtin types with a single argument. Speeds up range(x), list(x), and specifically type(obj).

  • bpo-42918: Fix bug where the built-in compile() function did not always raise a SyntaxError when passed multiple statements in ‘single’ mode. Patch by Weipeng Hong.

  • bpo-45953: The main interpreter in _PyRuntimeState.interpreters is now statically allocated (as part of _PyRuntime). Likewise for the initial thread state of each interpreter. This means less allocation during runtime init, as well as better memory locality for these key state objects.

  • bpo-45292: Complete the PEP 654 implementation: add except*.

  • bpo-43413: Revert changes in set.__init__. Subclass of set needs to define a __init__() method if it defines a __new__() method with additional keyword parameters.

  • bpo-43931: Added the Py_Version constant which bears the same value as PY_VERSION_HEX. Patch by Gabriele N. Tornetta.

Library

  • bpo-46342: The @typing.final decorator now sets the __final__ attribute on the decorated object to allow runtime introspection. Patch by Jelle Zijlstra.

  • bpo-46328: Added the sys.exception() method which returns the active exception instance.

  • bpo-46307: Add string.Template.is_valid() and string.Template.get_identifiers() methods.

  • bpo-46306: Assume that types.CodeType always has types.CodeType.co_firstlineno in doctest.

  • bpo-40479: Fix hashlib usedforsecurity option to work correctly with OpenSSL 3.0.0 in FIPS mode.

  • bpo-46070: Fix possible segfault when importing the asyncio module from different sub-interpreters in parallel. Patch by Erlend E. Aasland.

  • bpo-46244: Removed __slots__ from typing.ParamSpec and typing.TypeVar. They served no purpose. Patch by Arie Bovenberg.

  • bpo-46278: Reflect context argument in AbstractEventLoop.call_*() methods. Loop implementations already support it.

  • bpo-46269: Remove special-casing of __new__ in enum.Enum.__dir__().

  • bpo-46266: Improve day constants in calendar.

    Now all constants (MONDAY … SUNDAY) are documented, tested, and added to __all__.

  • bpo-46257: Optimized the mean, variance, and stdev functions in the statistics module. If the input is an iterator, it is consumed in a single pass rather than eating memory by conversion to a list. The single pass algorithm is about twice as fast as the previous two pass code.

  • bpo-41011: Added two new variables to pyvenv.cfg which is generated by venv module: executable for the executable and command for the command line used to create the environment.

  • bpo-46239: Improve error message when importing asyncio.windows_events on non-Windows.

  • bpo-46238: Reuse _winapi constants in asyncio.windows_events.

  • bpo-46222: Adding SF_NOCACHE sendfile constant for FreeBSD for the posixmodule.

  • bpo-37295: Add fast path for 0 <= k <= n <= 67 for math.comb().

  • bpo-46176: Adding the MAP_STACK constant for the mmap module.

  • bpo-43424: Deprecate webbrowser.MacOSXOSAScript._name and use name instead.

  • bpo-45321: Added missing error codes to module xml.parsers.expat.errors.

  • bpo-46125: Refactor tests to test traversable API directly. Includes changes from importlib 5.4.0.

  • bpo-46118: Moved importlib.resources and its related functionality to a package.

  • bpo-37578: Add include_hidden parameter to glob() and iglob() to match hidden files and directories when using special characters like *, **, ? and [].

  • bpo-20369: concurrent.futures.wait() no longer blocks forever when given duplicate Futures. Patch by Kumar Aditya.

  • bpo-46105: Honor spec when generating requirement specs with urls and extras (importlib_metadata 4.8.3).

  • bpo-44893: EntryPoint objects are no longer tuples. Recommended means to access is by attribute (‘.name’, ‘.group’) or accessor (‘.load()’). Access by index is deprecated and will raise deprecation warning.

  • bpo-22815: Print unexpected successes together with failures and errors in summary in unittest.TextTestResult.

  • bpo-22047: Calling add_argument_group() on an argument group is deprecated. Calling add_argument_group() or add_mutually_exclusive_group() on a mutually exclusive group is deprecated.

    These features were never supported and do not always work correctly. The functions exist on the API by accident through inheritance and will be removed in the future.

  • bpo-26952: argparse raises ValueError with clear message when trying to render usage for an empty mutually exclusive group. Previously it raised a cryptic IndexError.

  • bpo-45615: Functions in the traceback module raise TypeError rather than AttributeError when an exception argument is not of type BaseException.

  • bpo-16594: Add allow allow_reuse_port flag in socketserver.

  • bpo-27718: Fix help for the signal module. Some functions (e.g. signal() and getsignal()) were omitted.

  • bpo-46032: The registry() method of functools.singledispatch() functions checks now the first argument or the first parameter annotation and raises a TypeError if it is not supported. Previously unsupported “types” were ignored (e.g. typing.List[int]) or caused an error at calling time (e.g. list[int]).

  • bpo-46014: Add ability to use typing.Union and types.UnionType as dispatch argument to functools.singledispatch. Patch provided by Yurii Karabas.

  • bpo-27062: Add __all__ to inspect, patch by Kumar Aditya.

  • bpo-46018: Ensure that math.expm1() does not raise on underflow.

  • bpo-46016: Adding F_DUP2FD and F_DUP2FD_CLOEXEC constants from FreeBSD into the fcntl module.

  • bpo-45755: typing generic aliases now reveal the class attributes of the original generic class when passed to dir(). This was the behavior up to Python 3.6, but was changed in 3.7-3.9.

  • bpo-45874: The empty query string, consisting of no query arguments, is now handled correctly in urllib.parse.parse_qsl. This caused problems before when strict parsing was enabled.

  • bpo-44674: Change how dataclasses disallows mutable default values. It used to use a list of known types (list, dict, set). Now it disallows unhashable objects to be defaults. It’s using unhashability as a proxy for mutability. Patch by Eric V. Smith, idea by Raymond Hettinger.

  • bpo-23882: Remove namespace package (PEP 420) support from unittest discovery. It was introduced in Python 3.4 but has been broken since Python 3.7.

  • bpo-25066: Added a __repr__() method to multiprocessing.Event objects, patch by Kumar Aditya.

  • bpo-45643: Added signal.SIGSTKFLT on platforms where this signal is defined.

  • bpo-44092: Fetch across rollback no longer raises InterfaceError. Instead we leave it to the SQLite library to handle these cases. Patch by Erlend E. Aasland.

  • bpo-42413: Replace concurrent.futures.TimeoutError and asyncio.TimeoutError with builtin TimeoutError, keep these names as deprecated aliases.

Documentation

Tests

  • bpo-46296: Add a test case for enum with _use_args_ == True and _member_type_ == object.

  • bpo-46205: Fix hang in runtest_mp due to race condition

  • bpo-46263: Fix test_capi on FreeBSD 14-dev: instruct jemalloc to not fill freed memory with junk byte.

  • bpo-46262: Cover ValueError path in tests for enum.Flag._missing_().

  • bpo-46150: Now fakename in test_pathlib.PosixPathTest.test_expanduser is checked to be non-existent.

  • bpo-46129: Rewrite asyncio.locks tests with unittest.IsolatedAsyncioTestCase usage.

  • bpo-23819: Fixed asyncio tests in python optimized mode. Patch by Kumar Aditya.

  • bpo-46114: Fix test case for OpenSSL 3.0.1 version. OpenSSL 3.0 uses 0xMNN00PP0L.

Build

  • bpo-44133: When Python is configured with --without-static-libpython, the Python static library (libpython.a) is no longer built. Patch by Victor Stinner.

  • bpo-44133: When Python is built without --enable-shared, the python program is now linked to object files, rather than being linked to the Python static library (libpython.a), to make sure that all symbols are exported. Previously, the linker omitted some symbols like the Py_FrozenMain() function. Patch by Victor Stinner.

  • bpo-40280: The configure script has a new option --with-emscripten-target to select browser or node as Emscripten build target.

  • bpo-46315: Added and fixed #ifdef HAVE_FEATURE checks for functionality that is not available on WASI platform.

  • bpo-45723: Fixed a regression in configure check for select.epoll().

  • bpo-46263: configure no longer sets MULTIARCH on FreeBSD platforms.

  • bpo-46106: Updated OpenSSL to 1.1.1m in Windows builds, macOS installer builds, and CI. Patch by Kumar Aditya.

  • bpo-46088: Automatically detect or install bootstrap Python runtime when building from Visual Studio.

  • bpo-46072: Add a –with-pystats configure option to turn on internal statistics gathering.

  • bpo-40280: A new directory Tools/wasm contains WebAssembly-related helpers like config.site override for wasm32-emscripten, wasm assets generator to bundle the stdlib, and a README.

  • bpo-46023: makesetup no longer builds extensions that have been marked as disabled. This allows users to disable modules in Modules/Setup.local.

  • bpo-45949: Use pure Python freeze_module for all but importlib bootstrap files. --with-freeze-module configure option is no longer needed for cross builds.

Windows

  • bpo-46217: Removed parameter that is unsupported on Windows 8.1 and early Windows 10 and may have caused build or runtime failures.

macOS

  • bpo-40477: The Python Launcher app for macOS now properly launches scripts and, if necessary, the Terminal app when running on recent macOS releases.

C API

Python 3.11.0 alpha 3

Release date: 2021-12-08

Core and Builtins

  • bpo-46009: Restore behavior from 3.9 and earlier when sending non-None to newly started generator. In 3.9 this did not affect the state of the generator. In 3.10.0 and 3.10.1 gen_func().send(0) is equivalent to gen_func().throw(TypeError(...) which exhausts the generator. In 3.10.2 onward, the behavior has been reverted to that of 3.9.

  • bpo-46004: Fix the SyntaxError location for errors involving for loops with invalid targets. Patch by Pablo Galindo

  • bpo-45711: _PyErr_ChainStackItem() no longer normalizes exc_info (including setting the traceback on the exception instance) because exc_info is always normalized.

  • bpo-45607: The __note__ field was added to BaseException. It is None by default but can be set to a string which is added to the exception’s traceback.

  • bpo-45947: Place pointers to dict and values immediately before GC header. This reduces number of dependent memory loads to access either dict or values from 3 to 1.

  • bpo-45915: is_valid_fd now uses faster fcntl(fd, F_GETFD) on Linux, macOS, and Windows.

  • bpo-44530: Reverts a change to the code.__new__ audit event from an earlier prerelease.

  • bpo-42268: Fail the configure step if the selected compiler doesn’t support memory sanitizer. Patch by Pablo Galindo

  • bpo-45711: The three values of exc_info are now always consistent with each other. In particular, the type and traceback fields are now derived from the exception instance. This impacts the return values of sys.exc_info() and PyErr_GetExcInfo() if the exception instance is modified while the exception is handled, as well as PyErr_SetExcInfo(), which now ignores the type and traceback arguments provided to it.

  • bpo-45727: Refine the custom syntax error that suggests that a comma may be missing to trigger only when the expressions are detected between parentheses or brackets. Patch by Pablo Galindo

  • bpo-45885: Specialized the COMPARE_OP opcode using the PEP 659 machinery.

  • bpo-45786: Allocate space for the interpreter frame in the frame object, to avoid an additional allocation when the frame object outlives the frame activation.

  • bpo-45614: Fix traceback display for exceptions with invalid module name.

  • bpo-45813: Fix crash when calling coro.cr_frame.clear() after coroutine has been freed.

  • bpo-45811: Improve the tokenizer errors when encountering invisible control characters in the parser. Patch by Pablo Galindo

  • bpo-45848: Allow the parser to obtain error lines directly from encoded files. Patch by Pablo Galindo

  • bpo-45709: Restore behavior from 3.10 when tracing an exception raised within a with statement.

  • bpo-44525: Adds new COPY_FREE_VARS opcode, to make copying of free variables from function to frame explicit. Helps optimization of calls to Python function.

  • bpo-45829: Specialize BINARY_SUBSCR for classes with a __getitem__ method implemented in Python

  • bpo-45826: Fixed a crash when calling .with_traceback(None) on NameError. This occurs internally in unittest.TestCase.assertRaises().

  • bpo-45822: Fixed a bug in the parser that was causing it to not respect PEP 263 coding cookies when no flags are provided. Patch by Pablo Galindo

  • bpo-45820: Fix a segfault when the parser fails without reading any input. Patch by Pablo Galindo

  • bpo-45636: Simplify the implementation of BINARY_OP by indexing into an array of function pointers (rather than switching on the oparg).

  • bpo-42540: Fix crash when os.fork() is called with an active non-default memory allocator.

  • bpo-45738: Fix computation of error location for invalid continuation characters in the parser. Patch by Pablo Galindo.

  • bpo-45636: Remove an existing “fast path” for old-style string formatting, since it no longer appears to have any measurable impact.

  • bpo-45753: Make recursion checks a bit more efficient by tracking amount of calls left before overflow.

  • bpo-45773: Fix a compiler hang when attempting to optimize certain jump patterns.

  • bpo-45764: The parser now gives a better error message when leaving out the opening parenthesis ( after a def-statement:

    >>> def f:
  File "<stdin>", line 1
    def f:
         ^
SyntaxError: expected '('

  • bpo-45609: Specialized the STORE_SUBSCR opcode using the PEP 659 machinery.

  • bpo-45636: Replace all numeric BINARY_* and INPLACE_* instructions with a single BINARY_OP implementation.

  • bpo-45582: Path calculation (known as getpath) has been reimplemented as a frozen Python module. This should have no visible impact, but may affect calculation of all paths referenced in sys and sysconfig.

  • bpo-45450: Improve the syntax error message for parenthesized arguments. Patch by Pablo Galindo.

Library

  • bpo-27946: Fix possible crash when getting an attribute of xml.etree.ElementTree.Element simultaneously with replacing the attrib dict.

  • bpo-45711: Make asyncio normalize exceptions as soon as they are captured with PyErr_Fetch(), and before they are stored as an exc_info triplet. This brings asyncio in line with the rest of the codebase, where an exc_info triplet is always normalized.

  • bpo-23819: Replaced asserts with exceptions in asyncio, patch by Kumar Aditya.

  • bpo-13236: unittest.TextTestResult and unittest.TextTestRunner flush now the output stream more often.

  • bpo-45917: Added math.exp2():, which returns 2 raised to the power of x.

  • bpo-37658: Fix issue when on certain conditions asyncio.wait_for() may allow a coroutine to complete successfully, but fail to return the result, potentially causing memory leaks or other issues.

  • bpo-45876: Improve the accuracy of stdev() and pstdev() in the statistics module. When the inputs are floats or fractions, the output is a correctly rounded float

  • bpo-44649: Handle dataclass(slots=True) with a field that has default a default value, but for which init=False.

  • bpo-45803: Added missing kw_only parameter to dataclasses.make_dataclass().

  • bpo-45837: The turtle.RawTurtle.settiltangle() is deprecated since Python 3.1, it now emits a deprecation warning and will be removed in Python 3.13.

    Use turtle.RawTurtle.tiltangle() instead.

    turtle.RawTurtle.tiltangle() was earlier incorrectly marked as deprecated, its docstring has been corrected.

    Patch by Hugo van Kemenade.

  • bpo-45831: faulthandler can now write ASCII-only strings (like filenames and function names) with a single write() syscall when dumping a traceback. It reduces the risk of getting an unreadable dump when two threads or two processes dump a traceback to the same file (like stderr) at the same time. Patch by Victor Stinner.

  • bpo-45828: sqlite C callbacks now use unraisable exceptions if callback tracebacks are enabled. Patch by Erlend E. Aasland.

  • bpo-41735: Fix thread lock in zlib.Decompress.flush() method before PyObject_GetBuffer.

  • bpo-45235: Reverted an argparse bugfix that caused regression in the handling of default arguments for subparsers. This prevented leaf level arguments from taking precedence over root level arguments.

  • bpo-45754: Fix a regression in Python 3.11a1 and 3.11a2 where sqlite3 incorrectly would use SQLITE_LIMIT_LENGTH when checking SQL statement lengths. Now, SQLITE_LIMIT_SQL_LENGTH is used. Patch by Erlend E. Aasland.

  • bpo-45766: Added proportional option to statistics.linear_regression().

  • bpo-45765: In importlib.metadata, fix distribution discovery for an empty path.

  • bpo-45757: Fix bug where dis produced an incorrect oparg when EXTENDED_ARG is followed by an opcode that does not use its argument.

  • bpo-45644: In-place JSON file formatting using python3 -m json.tool infile infile now works correctly, previously it left the file empty. Patch by Chris Wesseling.

  • bpo-45703: When a namespace package is imported before another module from the same namespace is created/installed in a different sys.path location while the program is running, calling the importlib.invalidate_caches() function will now also guarantee the new module is noticed.

  • bpo-45535: Improve output of dir() with Enums.

  • bpo-45664: Fix types.resolve_bases() and types.new_class() for types.GenericAlias instance as a base.

  • bpo-45663: Fix dataclasses.is_dataclass() for dataclasses which are subclasses of types.GenericAlias.

  • bpo-45662: Fix the repr of dataclasses.InitVar with a type alias to the built-in class, e.g. InitVar[list[int]].

  • bpo-43137: Launch GNOME web browsers via gio tool instead of obsolete gvfs-open

  • bpo-45429: On Windows, time.sleep() now uses a waitable timer which supports high-resolution timers. Patch by Donghee Na and Eryk Sun.

  • bpo-37295: Optimize math.comb() and math.perm().

  • bpo-45514: Deprecated legacy functions in importlib.resources.

  • bpo-45507: Add tests for truncated/missing trailers in gzip.decompress implementation.

  • bpo-45359: Implement PEP 585 for graphlib.TopologicalSorter.

  • bpo-44733: Add max_tasks_per_child to concurrent.futures.ProcessPoolExecutor. This allows users to specify the maximum number of tasks a single process should execute before the process needs to be restarted.

  • bpo-28806: Improve netrc library. netrc file no longer needs to contain all tokens. And if the login name is anonymous, security check is no longer need.

  • bpo-43498: Avoid a possible “RuntimeError: dictionary changed size during iteration” when adjusting the process count of ProcessPoolExecutor.

  • bpo-42158: Add MIME types for N-quads, N-triples, Notation3 and TriG to mimetypes.

  • bpo-30533: Add inspect.getmembers_static() , it return all members without triggering dynamic lookup via the descriptor protocol. Patch by Weipeng Hong.

Documentation

  • bpo-42238: make -C Doc suspicious will be removed soon in favor of make -C Doc check, mark it as deprecated.

  • bpo-45840: Improve cross-references in the documentation for the data model.

  • bpo-45640: Properly marked-up grammar tokens in the documentation are now clickable and take you to the definition of a given piece of grammar. Patch by Arthur Milchior.

  • bpo-45788: Link doc for sys.prefix to sysconfig doc on installation paths.

  • bpo-45772: socket.socket documentation is corrected to a class from a function.

  • bpo-45392: Update the docstring of the type built-in to remove a redundant line and to mention keyword arguments for the constructor.

  • bpo-45250: Update the documentation to note that CPython does not consistently require iterators to define __iter__.

  • bpo-25381: In the extending chapter of the extending doc, update a paragraph about the global variables containing exception information.

  • bpo-43905: Expanded astuple() and asdict() docs, warning about deepcopy being applied and providing a workaround.

Tests

  • bpo-45695: Out-of-tree builds with a read-only source directory are now tested by CI.

  • bpo-19460: Add new Test for Lib/email/mime/nonmultipart.py::MIMENonMultipart.

  • bpo-45835: Fix race condition in test_queue tests with multiple “feeder” threads.

  • bpo-45783: The test for the freeze tool now handles file moves and deletions.

  • bpo-45745: Remove the --findleaks command line option of regrtest: use the --fail-env-changed option instead. Since Python 3.7, it was a deprecated alias to the --fail-env-changed option.

  • bpo-45701: Add tests with tuple type with functools.lru_cache() to test_functools.

Build

  • bpo-44035: CI now verifies that autoconf files have been regenerated with a current and unpatched autoconf package.

  • bpo-45950: The build system now uses a _bootstrap_python interpreter for freezing and deepfreezing again. To speed up build process the build tools _bootstrap_python and _freeze_module are no longer build with LTO.

  • bpo-45881: The configure script now accepts --with-build-python and --with-freeze-module options to make cross compiling easier.

  • bpo-40280: Emscripten platform now uses .wasm suffix by default.

  • bpo-40280: Disable unusable core extension modules on WASM/Emscripten targets.

  • bpo-40280: configure now checks for socket shutdown function. The check makes it possible to disable SYS_shutdown with ac_cv_func_shutdown=no in CONFIG_SITE.

  • bpo-40280: configure now checks for functions fork1, getegid, geteuid, getgid, getppid, getuid, opendir, pipe, system, wait, ttyname.

  • bpo-33393: Update config.guess to 2021-06-03 and config.sub to 2021-08-14. Makefile now has an update-config target to make updating more convenient.

  • bpo-45866: make regen-all now produces the same output when run from a directory other than the source tree: when building Python out of the source tree. pegen now strips directory of the “generated by pygen from <FILENAME>” header Patch by Victor Stinner.

  • bpo-40280: configure now accepts machine wasm32 or wasm64 and OS wasi or emscripten for cross building, e.g. wasm32-unknown-emscripten, wasm32-wasi, or wasm32-unknown-wasi.

  • bpo-41498: Python now compiles on platforms without sigset_t. Several functions in signal are not available when sigset_t is missing.

    Based on patch by Roman Yurchak for pyodide.

  • bpo-45881: setup.py now uses CC from environment first to discover multiarch and cross compile paths.

  • bpo-45886: The _freeze_module program path can now be overridden on the command line, e.g. make FREEZE_MODULE=../x86_64/Program/_freeze_module.

  • bpo-45873: Get rid of the _bootstrap_python build step. The deepfreeze.py script is now run using $(PYTHON_FOR_REGEN) which can be Python 3.7 or newer (on Windows, 3.8 or newer).

  • bpo-45847: Port builtin hashlib extensions to PY_STDLIB_MOD macro and addext().

  • bpo-45723: Add autoconf helpers for saving and restoring environment variables:

    • SAVE_ENV: Save $CFLAGS, $LDFLAGS, $LIBS, and $CPPFLAGS.

    • RESTORE_ENV: Restore $CFLAGS, $LDFLAGS, $LIBS, and $CPPFLAGS.

    • WITH_SAVE_ENV([SCRIPT]): Run SCRIPT wrapped with SAVE_ENV and RESTORE_ENV.

    Patch by Erlend E. Aasland.

  • bpo-45573: Mandatory core modules, that are required to bootstrap Python, are now in Modules/Setup.bootstrap.

  • bpo-45573: configure now creates Modules/Setup.stdlib with conditionally enabled/disabled extension module lines. The file is not used, yet.

  • bpo-45573: configure now uses a unified format to set state, compiler flags, and linker flags in Makefile. The new macro PY_STDLIB_MOD sets three variables that are consumed by Modules/Setup and setup.py.

  • bpo-45816: Python now supports building with Visual Studio 2022 (MSVC v143, VS Version 17.0). Patch by Jeremiah Vivian.

  • bpo-45800: Settings for pyexpat C extension are now detected by configure. The bundled expat library is built in Makefile.

  • bpo-45798: Settings for decimal internal C extension are now detected by configure. The bundled libmpdec library is built in Makefile.

  • bpo-45723: configure has a new option --with-pkg-config to disable or require pkg-config.

  • bpo-45774: The build dependencies for sqlite3 are now detected by configure and pkg-config. Patch by Erlend E. Aasland.

  • bpo-45763: The build dependencies for zlib, bz2, and lzma are now detected by configure.

  • bpo-45747: gdbm and dbm build dependencies are now detected by configure.

  • bpo-45743: On macOS, the build system no longer passes search_paths_first to the linker. The flag has been the default since Xcode 4 / macOS 10.6.

  • bpo-45723: configure.ac is now compatible with autoconf 2.71. Deprecated checks STDC_HEADERS and AC_HEADER_TIME have been removed.

  • bpo-45723: configure now prints a warning when pkg-config is missing.

  • bpo-45731: configure --enable-loadable-sqlite-extensions is now handled by new PY_SQLITE_ENABLE_LOAD_EXTENSION macro instead of logic in setup.py.

  • bpo-45723: configure.ac now uses custom helper macros and AC_CACHE_CHECK to simplify and speed up configure runs.

  • bpo-45696: Skip the marshal step for frozen modules by generating C code that produces a set of ready-to-use code objects. This speeds up startup time by another 10% or more.

  • bpo-45561: Run smelly.py tool from $(srcdir).

Windows

  • bpo-46105: Fixed calculation of sys.path in a venv on Windows.

  • bpo-45901: When installed through the Microsoft Store and set as the default app for *.py files, command line arguments will now be passed to Python when invoking a script without explicitly launching Python (that is, script.py args rather than python script.py args).

  • bpo-45616: Fix Python Launcher’s ability to distinguish between versions 3.1 and 3.10 when either one is explicitly requested. Previously, 3.1 would be used if 3.10 was requested but not installed, and 3.10 would be used if 3.1 was requested but 3.10 was installed.

  • bpo-45850: Implement changes to build with deep-frozen modules on Windows. Note that we now require Python 3.10 as the “bootstrap” or “host” Python.

  • bpo-45732: Updates bundled Tcl/Tk to 8.6.12.

  • bpo-45720: Internal reference to shlwapi.dll was dropped to help improve startup time. This DLL will no longer be loaded at the start of every Python process.

macOS

  • bpo-45732: Update python.org macOS installer to use Tcl/Tk 8.6.12.

C API

  • bpo-39026: Fix Python.h to build C extensions with Xcode: remove a relative include from Include/cpython/pystate.h.

Python 3.11.0 alpha 2

Release date: 2021-11-05

Core and Builtins

  • bpo-45716: Improve the SyntaxError message when using True, None or False as keywords in a function call. Patch by Pablo Galindo.

  • bpo-45688: sys.stdlib_module_names now contains the macOS-specific module _scproxy.

  • bpo-45379: Clarify ImportError message when we try to explicitly import a frozen module but frozen modules are disabled.

  • bpo-44525: Specialize simple calls to Python functions (no starargs, keyowrd dict, or closure)

  • bpo-45530: Cases of sorting using tuples as keys may now be significantly faster in some cases. Patch by Tim Peters.

    The order of the result may differ from earlier releases if the tuple elements don’t define a total ordering (see Value comparisons for information on total ordering). It’s generally true that the result of sorting simply isn’t well-defined in the absence of a total ordering on list elements.

  • bpo-45526: In obmalloc, set ADDRESS_BITS to not ignore any bits (ignored 16 before). That is safer in the case that the kernel gives user-space virtual addresses that span a range greater than 48 bits.

  • bpo-30570: Fixed a crash in issubclass() from infinite recursion when searching pathological __bases__ tuples.

  • bpo-45521: Fix a bug in the obmalloc radix tree code. On 64-bit machines, the bug causes the tree to hold 46-bits of virtual addresses, rather than the intended 48-bits.

  • bpo-45494: Fix parser crash when reporting errors involving invalid continuation characters. Patch by Pablo Galindo.

  • bpo-45445: Python now fails to initialize if it finds an invalid -X option in the command line. Patch by Pablo Galindo.

  • bpo-45340: Object attributes are held in an array instead of a dictionary. An object’s dictionary are created lazily, only when needed. Reduces the memory consumption of a typical Python object by about 30%. Patch by Mark Shannon.

  • bpo-45408: Fix a crash in the parser when reporting tokenizer errors that occur at the same time unclosed parentheses are detected. Patch by Pablo Galindo.

  • bpo-29410: Add SipHash13 for string hash algorithm and use it by default.

  • bpo-45385: Fix reference leak from descr_check. Patch by Donghee Na.

  • bpo-45367: Specialized the BINARY_MULTIPLY opcode to BINARY_MULTIPLY_INT and BINARY_MULTIPLY_FLOAT using the PEP 659 machinery.

  • bpo-21736: Frozen stdlib modules now have __file__ to the .py file they would otherwise be loaded from, if possible. For packages, __path__ now has the correct entry instead of being an empty list, which allows unfrozen submodules to be imported. These are set only if the stdlib directory is known when the runtime is initialized. Note that the file at __file__ is not guaranteed to exist. None of this affects non-stdlib frozen modules nor, for now, frozen modules imported using PyImport_ImportFrozenModule(). Also, at the moment co_filename is not updated for the module.

  • bpo-45020: For frozen stdlib modules, record the original module name as module.__spec__.loader_state.origname. If the value is different than module.__spec__.name then the module was defined as an alias in Tools/scripts/freeze_modules.py. If it is None then the module comes from a source file outside the stdlib.

  • bpo-45324: In FrozenImporter.find_spec(), we now preserve the information needed in exec_module() to load the module. This change mostly impacts internal details, rather than changing the importer’s behavior.

  • bpo-45292: Implement PEP 654. Add ExceptionGroup and BaseExceptionGroup. Update traceback display code.

  • bpo-40116: Change to the implementation of split dictionaries. Classes where the instances differ either in the exact set of attributes, or in the order in which those attributes are set, can still share keys. This should have no observable effect on users of Python or the C-API. Patch by Mark Shannon.

  • bpo-44050: Extensions that indicate they use global state (by setting m_size to -1) can again be used in multiple interpreters. This reverts to behavior of Python 3.8.

  • bpo-44525: Setup initial specialization infrastructure for the CALL_FUNCTION opcode. Implemented initial specializations for C function calls:

    • CALL_FUNCTION_BUILTIN_O for METH_O flag.

    • CALL_FUNCTION_BUILTIN_FAST for METH_FASTCALL flag without keywords.

    • CALL_FUNCTION_LEN for len(o).

    • CALL_FUNCTION_ISINSTANCE for isinstance(o, t).

  • bpo-44511: Improve the generated bytecode for class and mapping patterns.

  • bpo-43706: Speed up calls to enumerate() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

Library

  • bpo-45679: Fix caching of multi-value typing.Literal. Literal[True, 2] is no longer equal to Literal[1, 2].

  • bpo-42064: Convert sqlite3 to multi-phase initialisation (PEP 489). Patches by Erlend E. Aasland.

  • bpo-45438: Fix typing.Signature string representation for generic builtin types.

  • bpo-45613: sqlite3 now sets sqlite3.threadsafety based on the default threading mode the underlying SQLite library has been compiled with. Patch by Erlend E. Aasland.

  • bpo-45574: Fix warning about print_escape being unused.

  • bpo-45581: sqlite3.connect() now correctly raises MemoryError if the underlying SQLite API signals memory error. Patch by Erlend E. Aasland.

  • bpo-45557: pprint.pprint() now handles underscore_numbers correctly. Previously it was always setting it to False.

  • bpo-44019: Add operator.call() to operator.__all__. Patch by Kreusada.

  • bpo-42174: shutil.get_terminal_size() now falls back to sane values if the column or line count are 0.

  • bpo-35673: Improve the introspectability of the __loader__ attribute for namespace packages. importlib.machinery.NamespaceLoader is now public, and implements the importlib.abc.InspectLoader interface. _NamespaceLoader is kept for backward compatibility.

  • bpo-45515: Add references to zoneinfo in the datetime documentation, mostly replacing outdated references to dateutil.tz. Change by Paul Ganssle.

  • bpo-45475: Reverted optimization of iterating gzip.GzipFile, bz2.BZ2File, and lzma.LZMAFile (see bpo-43787) because it caused regression when user iterate them without having reference of them. Patch by Inada Naoki.

  • bpo-45489: Update ForwardRef to support | operator. Patch by Donghee Na.

  • bpo-42222: Removed deprecated support for float arguments in randrange().

  • bpo-45428: Fix a regression in py_compile when reading filenames from standard input.

  • bpo-45467: Fix incremental decoder and stream reader in the “raw-unicode-escape” codec. Previously they failed if the escape sequence was split.

  • bpo-45461: Fix incremental decoder and stream reader in the “unicode-escape” codec. Previously they failed if the escape sequence was split.

  • bpo-45239: Fixed email.utils.parsedate_tz() crashing with UnboundLocalError on certain invalid input instead of returning None. Patch by Ben Hoyt.

  • bpo-45417: Fix quadratic behaviour in the enum module: Creation of enum classes with a lot of entries was quadratic.

  • bpo-45249: Fix the behaviour of traceback.print_exc() when displaying the caret when the end_offset in the exception is set to 0. Patch by Pablo Galindo

  • bpo-45416: Fix use of asyncio.Condition with explicit asyncio.Lock objects, which was a regression due to removal of explicit loop arguments. Patch by Joongi Kim.

  • bpo-20028: Empty escapechar/quotechar is not allowed when initializing csv.Dialect. Patch by Vajrasky Kok and Donghee Na.

  • bpo-44904: Fix bug in the doctest module that caused it to fail if a docstring included an example with a classmethod property. Patch by Alex Waygood.

  • bpo-45406: Make inspect.getmodule() catch FileNotFoundError raised by inspect.getabsfile(), and return None to indicate that the module could not be determined.

  • bpo-45411: Add extensions for files containing subtitles - .srt & .vtt - to the mimetypes.py module.

  • bpo-10716: Migrated pydoc to HTML5 (without changing the look of it). Side effect is to update xmlrpc’s ServerHTMLDoc which now uses the CSS too. cgitb now relies less on pydoc (as it can’t use the CSS file).

  • bpo-27580: Add support of null characters in csv.

  • bpo-45262: Prevent use-after-free in asyncio. Make sure the cached running loop holder gets cleared on dealloc to prevent use-after-free in get_running_loop

  • bpo-45386: Make xmlrpc.client more robust to C runtimes where the underlying C strftime function results in a ValueError when testing for year formatting options.

  • bpo-20028: Improve error message of csv.Dialect when initializing. Patch by Vajrasky Kok and Donghee Na.

  • bpo-45343: Update bundled pip to 21.2.4 and setuptools to 58.1.0

  • bpo-45328: Fixed http.client.HTTPConnection to work properly in OSs that don’t support the TCP_NODELAY socket option.

  • bpo-45243: Add setlimit() and getlimit() to sqlite3.Connection for setting and getting SQLite limits by connection basis. Patch by Erlend E. Aasland.

  • bpo-45320: Removed from the inspect module:

    Patch by Hugo van Kemenade.

  • bpo-45192: Fix the tempfile._infer_return_type function so that the dir argument of the tempfile functions accepts an object implementing the os.PathLike protocol.

    Patch by Kyungmin Lee.

  • bpo-45160: When tracing a tkinter variable used by a ttk OptionMenu, callbacks are no longer made twice.

  • bpo-25625: Added non parallel-safe chdir() context manager to change the current working directory and then restore it on exit. Simple wrapper around chdir().

  • bpo-24139: Add support for SQLite extended result codes in sqlite3.Error. Patch by Erlend E. Aasland.

  • bpo-24444: Fixed an error raised in argparse help display when help for an option is set to 1+ blank spaces or when choices arg is an empty container.

  • bpo-44547: Implement Fraction.__int__, so that a fractions.Fraction instance f passes an isinstance(f, typing.SupportsInt) check.

  • bpo-40321: Adds support for HTTP 308 redirects to urllib. See RFC 7538 for details. Patch by Jochem Schulenklopper.

  • bpo-41374: Ensure that socket.TCP_* constants are exposed on Cygwin 3.1.6 and greater.

  • bpo-35970: Add help flag to the base64 module’s command line interface. Patch contributed by Robert Kuska.

Documentation

  • bpo-45726: Improve documentation for functools.singledispatch() and functools.singledispatchmethod.

  • bpo-45680: Amend the docs on GenericAlias objects to clarify that non-container classes can also implement __class_getitem__. Patch contributed by Alex Waygood.

  • bpo-45618: Update Sphinx version used to build the documentation to 4.2.0. Patch by Maciej Olko.

  • bpo-45655: Add a new “relevant PEPs” section to the top of the documentation for the typing module. Patch by Alex Waygood.

  • bpo-45604: Add level argument to multiprocessing.log_to_stderr function docs.

  • bpo-45516: Add protocol description to the importlib.abc.TraversableResources documentation.

  • bpo-45464: Mention in the documentation of Built-in Exceptions that inheriting from multiple exception types in a single subclass is not recommended due to possible memory layout incompatibility.

  • bpo-45449: Add note about PEP 585 in collections.abc.

  • bpo-45516: Add protocol description to the importlib.abc.Traversable documentation.

  • bpo-20692: Add Programming FAQ entry explaining that int literal attribute access requires either a space after or parentheses around the literal.

Tests

  • bpo-45678: Add tests for scenarios in which functools.singledispatchmethod is stacked on top of a method that has already been wrapped by two other decorators. Patch by Alex Waygood.

  • bpo-45578: Add tests for dis.distb()

  • bpo-45678: Add tests to ensure that functools.singledispatchmethod correctly wraps the attributes of the target function.

  • bpo-45668: PGO tests now pass when Python is built without test extension modules.

  • bpo-45577: Add subtests for all pickle protocols in test_zoneinfo.

  • bpo-45566: Fix test_frozen_pickle in test_dataclasses to check all pickle versions.

  • bpo-43592: test.libregrtest now raises the soft resource limit for the maximum number of file descriptors when the default is too low for our test suite as was often the case on macOS.

  • bpo-39679: Add more test cases for @functools.singledispatchmethod when combined with @classmethod or @staticmethod.

  • bpo-45410: When libregrtest spawns a worker process, stderr is now written into stdout to keep messages order. Use a single pipe for stdout and stderr, rather than two pipes. Previously, messages were out of order which made analysis of buildbot logs harder Patch by Victor Stinner.

  • bpo-45402: Fix test_tools.test_sundry() when Python is built out of tree: fix how the freeze_modules.py tool locates the _freeze_module program. Patch by Victor Stinner.

  • bpo-45403: Fix test_sys.test_stdlib_dir() when Python is built outside the source tree: compare normalized paths. Patch by Victor Stinner.

  • bpo-45400: Fix test_name_error_suggestions_do_not_trigger_for_too_many_locals() of test_exceptions if a directory name contains “a1” (like “Python-3.11.0a1”): use a stricter regular expression. Patch by Victor Stinner.

  • bpo-10572: Rename sqlite3 tests from test_sqlite to test_sqlite3, and relocate them to Lib/test/test_sqlite3. Patch by Erlend E. Aasland.

Build

  • bpo-43158: setup.py now uses values from configure script to build the _uuid extension module. Configure now detects util-linux’s libuuid, too.

  • bpo-45666: Fix warning of swprintf and %s usage in _testembed.c

  • bpo-45548: Modules/Setup and Modules/makesetup have been improved. The Setup file now contains working rules for all extensions. Outdated comments have been removed. Rules defined by makesetup track dependencies correctly.

  • bpo-45548: The math and cmath implementation now require a C99 compatible libm and no longer ship with workarounds for missing acosh, asinh, atanh, expm1, and log1p functions.

  • bpo-45595: setup.py and makesetup now track build dependencies on all Python header files and module specific header files.

  • bpo-45571: Modules/Setup now use PY_CFLAGS_NODIST instead of PY_CFLAGS to compile shared modules.

  • bpo-45570: pyexpat and _elementtree no longer define obsolete macros HAVE_EXPAT_CONFIG_H and USE_PYEXPAT_CAPI. XML_POOR_ENTROPY is now defined in expat_config.h.

  • bpo-43974: setup.py no longer defines Py_BUILD_CORE_MODULE. Instead every module, that uses the internal API, defines the macro.

  • bpo-45548: Fill in missing entries in Modules/Setup.

  • bpo-45532: Update sys.version to use main as fallback information. Patch by Jeong YunWon.

  • bpo-45536: The configure script now checks whether OpenSSL headers and libraries provide required APIs. Most common APIs are verified. The check detects outdated or missing OpenSSL. Failures do not stop configure.

  • bpo-45221: Fixed regression in handling of LDFLAGS and CPPFLAGS options where argparse.parse_known_args() could interpret an option as one of the built-in command line argument, for example -h for help.

  • bpo-45440: Building Python now requires a C99 <math.h> header file providing the following functions: copysign(), hypot(), isfinite(), isinf(), isnan(), round(). Patch by Victor Stinner.

  • bpo-45405: Prevent internal configure error when running configure with recent versions of non-Apple clang. Patch by David Bohman.

  • bpo-45433: Avoid linking libpython with libcrypt.

Windows

  • bpo-43652: Update Tcl/Tk to 8.6.11, actually this time. The previous update incorrectly included 8.6.10.

  • bpo-45337: venv now warns when the created environment may need to be accessed at a different path, due to redirections, links or junctions. It also now correctly installs or upgrades components when the alternate path is required.

  • bpo-43851: Build SQLite SQLITE_OMIT_AUTOINIT on Windows. Patch by Erlend E. Aasland.

macOS

  • bpo-44828: Avoid tkinter file dialog failure on macOS 12 Monterey when using the Tk 8.6.11 provided by python.org macOS installers. Patch by Marc Culler of the Tk project.

IDLE

  • bpo-45495: Add context keywords ‘case’ and ‘match’ to completions list.

C API

  • bpo-29103: PyType_FromSpec* now copies the class name from the spec to a buffer owned by the class, so the original can be safely deallocated. Patch by Petr Viktorin.

  • bpo-45522: The internal freelists for frame, float, list, dict, async generators, and context objects can now be disabled.

  • bpo-35134: Exclude PyWeakref_GET_OBJECT() from the limited C API. It never worked since the PyWeakReference structure is opaque in the limited C API.

  • bpo-35081: Move the interpreteridobject.h header file from Include/ to Include/internal/. It only provides private functions. Patch by Victor Stinner.

  • bpo-35134: The non-limited API files cellobject.h, classobject.h, context.h, funcobject.h, genobject.h and longintrepr.h have been moved to the Include/cpython directory. Moreover, the eval.h header file was removed. These files must not be included directly, as they are already included in Python.h: Include Files. If they have been included directly, consider including Python.h instead. Patch by Victor Stinner.

  • bpo-45474: The following items are no longer available when Py_LIMITED_API is defined:

    These are not part of the limited API.

    Patch by Victor Stinner.

  • bpo-45434: Remove the pystrhex.h header file. It only contains private functions. C extensions should only include the main <Python.h> header file. Patch by Victor Stinner.

  • bpo-45440: Remove the Py_FORCE_DOUBLE() macro. It was used by the Py_IS_INFINITY() macro. Patch by Victor Stinner.

  • bpo-45434: <Python.h> no longer includes the header files <stdlib.h>, <stdio.h>, <errno.h> and <string.h> when the Py_LIMITED_API macro is set to 0x030b0000 (Python 3.11) or higher. C extensions should explicitly include the header files after #include <Python.h>. Patch by Victor Stinner.

  • bpo-41123: Remove Py_UNICODE_COPY() and Py_UNICODE_FILL() macros, deprecated since Python 3.3. Use PyUnicode_CopyCharacters() or memcpy() (wchar_t* string), and PyUnicode_Fill() functions instead. Patch by Victor Stinner.

  • bpo-45412: Remove the following math macros using the errno variable:

    • Py_ADJUST_ERANGE1()

    • Py_ADJUST_ERANGE2()

    • Py_OVERFLOWED()

    • Py_SET_ERANGE_IF_OVERFLOW()

    • Py_SET_ERRNO_ON_MATH_ERROR()

    Patch by Victor Stinner.

  • bpo-45395: Custom frozen modules (the array set to PyImport_FrozenModules) are now treated as additions, rather than replacing all the default frozen modules. Frozen stdlib modules can still be disabled by setting the “code” field of the custom array entry to NULL.

  • bpo-43760: Add new PyThreadState_EnterTracing(), and PyThreadState_LeaveTracing() functions to the limited C API to suspend and resume tracing and profiling. Patch by Victor Stinner.

  • bpo-44220: PyStructSequence_UnnamedField is added to the Stable ABI.

Python 3.11.0 alpha 1

Release date: 2021-10-05

Security

  • bpo-42278: Replaced usage of tempfile.mktemp() with TemporaryDirectory to avoid a potential race condition.

  • bpo-44600: Fix incorrect line numbers while tracing some failed patterns in match statements. Patch by Charles Burkland.

  • bpo-41180: Add auditing events to the marshal module, and stop raising code.__init__ events for every unmarshalled code object. Directly instantiated code objects will continue to raise an event, and audit event handlers should inspect or collect the raw marshal data. This reduces a significant performance overhead when loading from .pyc files.

  • bpo-44394: Update the vendored copy of libexpat to 2.4.1 (from 2.2.8) to get the fix for the CVE-2013-0340 “Billion Laughs” vulnerability. This copy is most used on Windows and macOS.

  • bpo-43124: Made the internal putcmd function in smtplib sanitize input for presence of \r and \n characters to avoid (unlikely) command injection.

  • bpo-44022: http.client now avoids infinitely reading potential HTTP headers after a 100 Continue status response from the server.

Core and Builtins

  • bpo-43760: The number of hardware branches per instruction dispatch is reduced from two to one by adding a special instruction for tracing. Patch by Mark Shannon.

  • bpo-45061: Add a deallocator to the bool type to detect refcount bugs in C extensions which call Py_DECREF(Py_True) or Py_DECREF(Py_False) by mistake. Detect also refcount bugs when the empty tuple singleton or the Unicode empty string singleton is destroyed by mistake. Patch by Victor Stinner.

  • bpo-24076: sum() was further optimised for summing up single digit integers.

  • bpo-45190: Update Unicode databases to Unicode 14.0.0.

  • bpo-45167: Fix deepcopying of types.GenericAlias objects.

  • bpo-45155: int.to_bytes() and int.from_bytes() now take a default value of "big" for the byteorder argument. int.to_bytes() also takes a default value of 1 for the length argument.

  • bpo-44219: Release the GIL while performing isatty system calls on arbitrary file descriptors. In particular, this affects os.isatty(), os.device_encoding() and io.TextIOWrapper. By extension, io.open() in text mode is also affected. This change solves a deadlock in os.isatty(). Patch by Vincent Michel in bpo-44219.

  • bpo-44959: Added fallback to extension modules with ‘.sl’ suffix on HP-UX

  • bpo-45121: Fix issue where Protocol.__init__ raises RecursionError when it’s called directly or via super(). Patch provided by Yurii Karabas.

  • bpo-44348: The deallocator function of the BaseException type now uses the trashcan mechanism to prevent stack overflow. For example, when a RecursionError instance is raised, it can be linked to another RecursionError through the __context__ attribute or the __traceback__ attribute, and then a chain of exceptions is created. When the chain is destroyed, nested deallocator function calls can crash with a stack overflow if the chain is too long compared to the available stack memory. Patch by Victor Stinner.

  • bpo-45123: Fix PyAiter_Check to only check for the __anext__ presence (not for __aiter__). Rename PyAiter_Check to PyAIter_Check, PyObject_GetAiter -> PyObject_GetAIter.

  • bpo-1514420: Interpreter no longer attempts to open files with names in angle brackets (like “<string>” or “<stdin>”) when formatting an exception.

  • bpo-41031: Match C and Python code formatting of unprintable exceptions and exceptions in the __main__ module.

  • bpo-37330: open(), io.open(), codecs.open() and fileinput.FileInput no longer accept 'U' (“universal newline”) in the file mode. This flag was deprecated since Python 3.3. Patch by Victor Stinner.

  • bpo-45083: When the interpreter renders an exception, its name now has a complete qualname. Previously only the class name was concatenated to the module name, which sometimes resulted in an incorrect full name being displayed.

    (This issue impacted only the C code exception rendering, the traceback module was using qualname already).

  • bpo-34561: List sorting now uses the merge-ordering strategy from Munro and Wild’s powersort(). Unlike the former strategy, this is provably near-optimal in the entropy of the distribution of run lengths. Most uses of list.sort() probably won’t see a significant time difference, but may see significant improvements in cases where the former strategy was exceptionally poor. However, as these are all fast linear-time approximations to a problem that’s inherently at best quadratic-time to solve truly optimally, it’s also possible to contrive cases where the former strategy did better.

  • bpo-45056: Compiler now removes trailing unused constants from co_consts.

  • bpo-45020: Add a new command line option, “-X frozen_modules=[on|off]” to opt out of (or into) using optional frozen modules. This defaults to “on” (or “off” if it’s running out of the source tree).

  • bpo-45012: In posix, release GIL during stat(), lstat(), and fstatat() syscalls made by os.DirEntry.stat(). Patch by Stanisław Skonieczny.

  • bpo-45018: Fixed pickling of range iterators that iterated for over 2**32 times.

  • bpo-45000: A SyntaxError is now raised when trying to delete __debug__. Patch by Donghee Na.

  • bpo-44963: Implement send() and throw() methods for anext_awaitable objects. Patch by Pablo Galindo.

  • bpo-44962: Fix a race in WeakKeyDictionary, WeakValueDictionary and WeakSet when two threads attempt to commit the last pending removal. This fixes asyncio.create_task and fixes a data loss in asyncio.run where shutdown_asyncgens is not run

  • bpo-24234: Implement the __bytes__() special method on the bytes type, so a bytes object b passes an isinstance(b, typing.SupportsBytes) check.

  • bpo-24234: Implement the __complex__() special method on the complex type, so a complex number z passes an isinstance(z, typing.SupportsComplex) check.

  • bpo-44954: Fixed a corner case bug where the result of float.fromhex('0x.8p-1074') was rounded the wrong way.

  • bpo-44947: Refine the syntax error for trailing commas in import statements. Patch by Pablo Galindo.

  • bpo-44945: Specialize the BINARY_ADD instruction using the PEP 659 machinery. Adds five new instructions:

    • BINARY_ADD_ADAPTIVE

    • BINARY_ADD_FLOAT

    • BINARY_ADD_INT

    • BINARY_ADD_UNICODE

    • BINARY_ADD_UNICODE_INPLACE_FAST

  • bpo-44929: Fix some edge cases of enum.Flag string representation in the REPL. Patch by Pablo Galindo.

  • bpo-44914: Class version tags are no longer recycled.

    This means that a version tag serves as a unique identifier for the state of a class. We rely on this for effective specialization of the LOAD_ATTR and other instructions.

  • bpo-44698: Restore behaviour of complex exponentiation with integer-valued exponent of type float or complex.

  • bpo-44895: A debug variable PYTHONDUMPREFSFILE is added for creating a dump file which is generated by --with-trace-refs. Patch by Donghee Na.

  • bpo-44900: Add five superinstructions for PEP 659 quickening:

    • LOAD_FAST LOAD_FAST

    • STORE_FAST LOAD_FAST

    • LOAD_FAST LOAD_CONST

    • LOAD_CONST LOAD_FAST

    • STORE_FAST STORE_FAST

  • bpo-44889: Initial implementation of adaptive specialization of LOAD_METHOD. The following specialized forms were added:

    • LOAD_METHOD_CACHED

    • LOAD_METHOD_MODULE

    • LOAD_METHOD_CLASS

  • bpo-44890: Specialization stats are always collected in debug builds.

  • bpo-44885: Correct the ast locations of f-strings with format specs and repeated expressions. Patch by Pablo Galindo

  • bpo-44878: Remove the loop from the bytecode interpreter. All instructions end with a DISPATCH macro, so the loop is now redundant.

  • bpo-44878: Remove switch statement for interpreter loop when using computed gotos. This makes sure that we only have one dispatch table in the interpreter.

  • bpo-44874: Deprecate the old trashcan macros (Py_TRASHCAN_SAFE_BEGIN/Py_TRASHCAN_SAFE_END). They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

  • bpo-44872: Use new trashcan macros (Py_TRASHCAN_BEGIN/END) in frameobject.c instead of the old ones (Py_TRASHCAN_SAFE_BEGIN/END).

  • bpo-33930: Fix segmentation fault with deep recursion when cleaning method objects. Patch by Augusto Goulart and Pablo Galindo.

  • bpo-25782: Fix bug where PyErr_SetObject hangs when the current exception has a cycle in its context chain.

  • bpo-44856: Fix reference leaks in the error paths of update_bases() and __build_class__. Patch by Pablo Galindo.

  • bpo-44826: Initial implementation of adaptive specialization of STORE_ATTR

    Three specialized forms of STORE_ATTR are added:

    • STORE_ATTR_SLOT

    • STORE_ATTR_SPLIT_KEYS

    • STORE_ATTR_WITH_HINT

  • bpo-44838: Fixed a bug that was causing the parser to raise an incorrect custom SyntaxError for invalid ‘if’ expressions. Patch by Pablo Galindo.

  • bpo-44821: Create instance dictionaries (__dict__) eagerly, to improve regularity of object layout and assist specialization.

  • bpo-44792: Improve syntax errors for if expressions. Patch by Miguel Brito

  • bpo-34013: Generalize the invalid legacy statement custom error message (like the one generated when “print” is called without parentheses) to include more generic expressions. Patch by Pablo Galindo

  • bpo-44732: Rename types.Union to types.UnionType.

  • bpo-44725: Expose specialization stats in python via _opcode.get_specialization_stats().

  • bpo-44717: Improve AttributeError on circular imports of submodules.

  • bpo-44698: Fix undefined behaviour in complex object exponentiation.

  • bpo-44653: Support typing types in parameter substitution in the union type.

  • bpo-44676: Add ability to serialise types.Union objects. Patch provided by Yurii Karabas.

  • bpo-44633: Parameter substitution of the union type with wrong types now raises TypeError instead of returning NotImplemented.

  • bpo-44661: Update property_descr_set to use vectorcall if possible. Patch by Donghee Na.

  • bpo-44662: Add __module__ to types.Union. This also fixes types.Union issues with typing.Annotated. Patch provided by Yurii Karabas.

  • bpo-44655: Include the name of the type in unset __slots__ attribute errors. Patch by Pablo Galindo

  • bpo-44655: Don’t include a missing attribute with the same name as the failing one when offering suggestions for missing attributes. Patch by Pablo Galindo

  • bpo-44646: Fix the hash of the union type: it no longer depends on the order of arguments.

  • bpo-44636: Collapse union of equal types. E.g. the result of int | int is now int. Fix comparison of the union type with non-hashable objects. E.g. int | str == {} no longer raises a TypeError.

  • bpo-44611: On Windows, os.urandom(): uses BCryptGenRandom API instead of CryptGenRandom API which is deprecated from Microsoft Windows API. Patch by Donghee Na.

  • bpo-44635: Convert None to type(None) in the union type constructor.

  • bpo-26280: Implement adaptive specialization for BINARY_SUBSCR

    Three specialized forms of BINARY_SUBSCR are added:

    • BINARY_SUBSCR_LIST_INT

    • BINARY_SUBSCR_TUPLE_INT

    • BINARY_SUBSCR_DICT

  • bpo-44589: Mapping patterns in match statements with two or more equal literal keys will now raise a SyntaxError at compile-time.

  • bpo-44606: Fix __instancecheck__ and __subclasscheck__ for the union type.

  • bpo-42073: The @classmethod decorator can now wrap other classmethod-like descriptors.

  • bpo-41972: Tuned the string-searching algorithm of fastsearch.h to have a shorter inner loop for most cases.

  • bpo-44590: All necessary data for executing a Python function (local variables, stack, etc) is now kept in a per-thread stack. Frame objects are lazily allocated on demand. This increases performance by about 7% on the standard benchmark suite. Introspection and debugging are unaffected as frame objects are always available when needed. Patch by Mark Shannon.

  • bpo-44584: The threading debug (PYTHONTHREADDEBUG environment variable) is deprecated in Python 3.10 and will be removed in Python 3.12. This feature requires a debug build of Python. Patch by Victor Stinner.

  • bpo-43895: An obsolete internal cache of shared object file handles added in 1995 that attempted, but did not guarantee, that a .so would not be dlopen’ed twice to work around flaws in mid-1990s posix-ish operating systems has been removed from dynload_shlib.c.

  • bpo-44490: typing now searches for type parameters in types.Union objects. get_type_hints will also properly resolve annotations with nested types.Union objects. Patch provided by Yurii Karabas.

  • bpo-43950: Code objects can now provide the column information for instructions when available. This is levaraged during traceback printing to show the expressions responsible for errors.

    Contributed by Pablo Galindo, Batuhan Taskaya and Ammar Askar as part of PEP 657.

  • bpo-44562: Remove uses of PyObject_GC_Del() in error path when initializing types.GenericAlias.

  • bpo-41486: Fix a memory consumption and copying performance regression in earlier 3.10 beta releases if someone used an output buffer larger than 4GiB with zlib.decompress on input data that expands that large.

  • bpo-43908: Heap types with the Py_TPFLAGS_IMMUTABLETYPE flag can now inherit the PEP 590 vectorcall protocol. Previously, this was only possible for static types. Patch by Erlend E. Aasland.

  • bpo-44553: Implement GC methods for types.Union to break reference cycles and prevent memory leaks.

  • bpo-44490: Add __parameters__ attribute and __getitem__ operator to types.Union. Patch provided by Yurii Karabas.

  • bpo-44523: Remove the pass-through for hash() of weakref.proxy objects to prevent unintended consequences when the original referred object dies while the proxy is part of a hashable object. Patch by Pablo Galindo.

  • bpo-44483: Fix a crash in types.Union objects when creating a union of an object with bad __module__ field.

  • bpo-44486: Modules will always have a dictionary, even when created by types.ModuleType.__new__()

  • bpo-44472: Fix ltrace functionality when exceptions are raised. Patch by Pablo Galindo

  • bpo-12022: A TypeError is now raised instead of an AttributeError in with and async with statements for objects which do not support the context manager or asynchronous context manager protocols correspondingly.

  • bpo-44297: Make sure that the line number is set when entering a comprehension scope. Ensures that backtraces inclusing generator expressions show the correct line number.

  • bpo-44456: Improve the syntax error when mixing positional and keyword patterns. Patch by Pablo Galindo.

  • bpo-44409: Fix error location information for tokenizer errors raised on initialization of the tokenizer. Patch by Pablo Galindo.

  • bpo-44396: Fix a possible crash in the tokenizer when raising syntax errors for unclosed strings. Patch by Pablo Galindo.

  • bpo-44376: Exact integer exponentiation (like i**2 or pow(i, 2)) with a small exponent is much faster, due to reducing overhead in such cases.

  • bpo-44313: Directly imported objects and modules (through import and from import statements) don’t generate LOAD_METHOD/CALL_METHOD for directly accessed objects on their namespace. They now use the regular LOAD_ATTR/CALL_FUNCTION.

  • bpo-44338: Implement adaptive specialization for LOAD_GLOBAL

    Two specialized forms of LOAD_GLOBAL are added:

    • LOAD_GLOBAL_MODULE

    • LOAD_GLOBAL_BUILTIN

  • bpo-44368: Improve syntax errors for invalid “as” targets. Patch by Pablo Galindo

  • bpo-44349: Fix an edge case when displaying text from files with encoding in syntax errors. Patch by Pablo Galindo.

  • bpo-44337: Initial implementation of adaptive specialization of LOAD_ATTR

    Four specialized forms of LOAD_ATTR are added:

    • LOAD_ATTR_SLOT

    • LOAD_ATTR_SPLIT_KEYS

    • LOAD_ATTR_WITH_HINT

    • LOAD_ATTR_MODULE

  • bpo-44335: Fix a regression when identifying incorrect characters in syntax errors. Patch by Pablo Galindo

  • bpo-43693: Computation of the offsets of cell variables is done in the compiler instead of at runtime. This reduces the overhead of handling cell and free variables, especially in the case where a variable is both an argument and cell variable.

  • bpo-44317: Improve tokenizer error with improved locations. Patch by Pablo Galindo.

  • bpo-44304: Fix a crash in the sqlite3 module that happened when the garbage collector clears sqlite.Statement objects. Patch by Pablo Galindo

  • bpo-44305: Improve error message for try blocks without except or finally blocks. Patch by Pablo Galindo.

  • bpo-43413: Constructors of subclasses of some builtin classes (e.g. tuple, list, frozenset) no longer accept arbitrary keyword arguments. [reverted in 3.11a4] Subclass of set can now define a __new__() method with additional keyword parameters without overriding also __init__().

  • bpo-43667: Improve Unicode support in non-UTF locales on Oracle Solaris. This issue does not affect other Solaris systems.

  • bpo-43693: A new opcode MAKE_CELL has been added that effectively moves some of the work done on function entry into the compiler and into the eval loop. In addition to creating the required cell objects, the new opcode converts relevant arguments (and other locals) to cell variables on function entry.

  • bpo-44232: Fix a regression in type() when a metaclass raises an exception. The C function type_new() must properly report the exception when a metaclass constructor raises an exception and the winner class is not the metaclass. Patch by Victor Stinner.

  • bpo-44201: Avoid side effects of checking for specialized syntax errors in the REPL that was causing it to ask for extra tokens after a syntax error had been detected. Patch by Pablo Galindo

  • bpo-43693: PyCodeObject gained co_fastlocalnames and co_fastlocalkinds as the authoritative source of fast locals info. Marshaled code objects have changed accordingly.

  • bpo-44184: Fix a crash at Python exit when a deallocator function removes the last strong reference to a heap type. Patch by Victor Stinner.

  • bpo-44187: Implement quickening in the interpreter. This offers no advantages as yet, but is an enabler of future optimizations. See PEP 659 for full explanation.

  • bpo-44180: The parser doesn’t report generic syntax errors that happen in a position further away that the one it reached in the first pass. Patch by Pablo Galindo

  • bpo-44168: Fix error message in the parser involving keyword arguments with invalid expressions. Patch by Pablo Galindo

  • bpo-44156: String caches in compile.c are now subinterpreter compatible.

  • bpo-44143: Fixed a crash in the parser that manifest when raising tokenizer errors when an existing exception was present. Patch by Pablo Galindo.

  • bpo-44032: Move ‘fast’ locals and other variables from the frame object to a per-thread datastack.

  • bpo-44114: Fix incorrect dictkeys_reversed and dictitems_reversed function signatures in C code, which broke webassembly builds.

  • bpo-44110: Improve str.__getitem__() error message

  • bpo-26110: Add CALL_METHOD_KW opcode to speed up method calls with keyword arguments. Idea originated from PyPy. A side effect is executing CALL_METHOD is now branchless in the evaluation loop.

  • bpo-28307: Compiler now optimizes simple C-style formatting with literal format containing only format codes %s, %r and %a by converting them to f-string expressions.

  • bpo-43149: Correct the syntax error message regarding multiple exception types to not refer to “exception groups”. Patch by Pablo Galindo

  • bpo-43822: The parser will prioritize tokenizer errors over custom syntax errors when raising exceptions. Patch by Pablo Galindo.

  • bpo-40222: “Zero cost” exception handling.

    • Uses a lookup table to determine how to handle exceptions.

    • Removes SETUP_FINALLY and POP_TOP block instructions, eliminating the runtime overhead of try statements.

    • Reduces the size of the frame object by about 60%.

    Patch by Mark Shannon

  • bpo-43918: Document the signature and default argument in the docstring of the new anext builtin.

  • bpo-43833: Emit a deprecation warning if the numeric literal is immediately followed by one of keywords: and, else, for, if, in, is, or. Raise a syntax error with more informative message if it is immediately followed by other keyword or identifier.

  • bpo-43879: Add native_thread_id to PyThreadState. Patch by Gabriele N. Tornetta.

  • bpo-43693: Compute cell offsets relative to locals in compiler. Allows the interpreter to treats locals and cells a single array, which is slightly more efficient. Also make the LOAD_CLOSURE opcode an alias for LOAD_FAST. Preserving LOAD_CLOSURE helps keep bytecode a bit more readable.

  • bpo-17792: More accurate error messages for access of unbound locals or free vars.

  • bpo-28146: Fix a confusing error message in str.format().

  • bpo-11105: When compiling ast.AST objects with recursive references through compile(), the interpreter doesn’t crash anymore instead it raises a RecursionError.

  • bpo-39091: Fix crash when using passing a non-exception to a generator’s throw() method. Patch by Noah Oxer

  • bpo-33346: Asynchronous comprehensions are now allowed inside comprehensions in asynchronous functions. Outer comprehensions implicitly become asynchronous.

Library

  • bpo-45371: Fix clang rpath issue in distutils. The UnixCCompiler now uses correct clang option to add a runtime library directory (rpath) to a shared library.

  • bpo-45329: Fix freed memory access in pyexpat.xmlparser when building it with an installed expat library <= 2.2.0.

  • bpo-41710: On Unix, if the sem_clockwait() function is available in the C library (glibc 2.30 and newer), the threading.Lock.acquire() method now uses the monotonic clock (time.CLOCK_MONOTONIC) for the timeout, rather than using the system clock (time.CLOCK_REALTIME), to not be affected by system clock changes. Patch by Victor Stinner.

  • bpo-1596321: Fix the threading._shutdown() function when the threading module was imported first from a thread different than the main thread: no longer log an error at Python exit.

  • bpo-45274: Fix a race condition in the Thread.join() method of the threading module. If the function is interrupted by a signal and the signal handler raises an exception, make sure that the thread remains in a consistent state to prevent a deadlock. Patch by Victor Stinner.

  • bpo-21302: In Unix operating systems, time.sleep() now uses the nanosleep() function, if clock_nanosleep() is not available but nanosleep() is available. nanosleep() allows to sleep with nanosecond precision.

  • bpo-21302: On Windows, time.sleep() now uses a waitable timer which has a resolution of 100 nanoseconds (10-7 seconds). Previously, it had a resolution of 1 millisecond (10-3 seconds). Patch by Benjamin Szőke and Victor Stinner.

  • bpo-45238: Fix unittest.IsolatedAsyncioTestCase.debug(): it runs now asynchronous methods and callbacks.

  • bpo-36674: unittest.TestCase.debug() raises now a unittest.SkipTest if the class or the test method are decorated with the skipping decorator.

  • bpo-45235: Fix an issue where argparse would not preserve values in a provided namespace when using a subparser with defaults.

  • bpo-45183: Have zipimport.zipimporter.find_spec() not raise an exception when the underlying zip file has been deleted and the internal cache has been reset via invalidate_cache().

  • bpo-45234: Fixed a regression in copyfile(), copy(), copy2() raising FileNotFoundError when source is a directory, which should raise IsADirectoryError

  • bpo-45228: Fix stack buffer overflow in parsing J1939 network address.

  • bpo-45225: use map function instead of genexpr in capwords.

  • bpo-42135: Fix typo: importlib.find_loader is really slated for removal in Python 3.12 not 3.10, like the others in PR 25169.

    Patch by Hugo van Kemenade.

  • bpo-20524: Improves error messages on .format() operation for str, float, int, and complex. New format now shows the problematic pattern and the object type.

  • bpo-45168: Change dis.dis() output to omit op arg values that cannot be resolved due to co_consts, co_names etc not being provided. Previously the oparg itself was repeated in the value field, which is not useful and can be confusing.

  • bpo-21302: In Unix operating systems, time.sleep() now uses the clock_nanosleep() function, if available, which allows to sleep for an interval specified with nanosecond precision.

  • bpo-45173: Remove from the configparser module: the SafeConfigParser class, the filename property of the ParsingError class, the readfp() method of the ConfigParser class, deprecated since Python 3.2.

    Patch by Hugo van Kemenade.

  • bpo-44987: Pure ASCII strings are now normalized in constant time by unicodedata.normalize(). Patch by Donghee Na.

  • bpo-35474: Calling mimetypes.guess_all_extensions() with strict=False no longer affects the result of the following call with strict=True. Also, mutating the returned list no longer affects the global state.

  • bpo-45166: typing.get_type_hints() now works with Final wrapped in ForwardRef.

  • bpo-45162: Remove many old deprecated unittest features:

    • “fail*” and “assert*” aliases of TestCase methods.

    • Broken from start TestCase method assertDictContainsSubset().

    • Ignored <unittest.TestLoader.loadTestsFromModule> TestLoader.loadTestsFromModule() parameter use_load_tests.

    • Old alias _TextTestResult of TextTestResult.

  • bpo-38371: Remove the deprecated split() method of _tkinter.TkappType. Patch by Erlend E. Aasland.

  • bpo-20499: Improve the speed and accuracy of statistics.pvariance().

  • bpo-45132: Remove __getitem__() methods of xml.dom.pulldom.DOMEventStream, wsgiref.util.FileWrapper and fileinput.FileInput, deprecated since Python 3.9.

    Patch by Hugo van Kemenade.

  • bpo-45129: Due to significant security concerns, the reuse_address parameter of asyncio.loop.create_datagram_endpoint(), disabled in Python 3.9, is now entirely removed. This is because of the behavior of the socket option SO_REUSEADDR in UDP.

    Patch by Hugo van Kemenade.

  • bpo-45124: The bdist_msi command, deprecated in Python 3.9, is now removed.

    Use bdist_wheel (wheel packages) instead.

    Patch by Hugo van Kemenade.

  • bpo-30856: unittest.TestResult methods addFailure(), addError(), addSkip() and addSubTest() are now called immediately after raising an exception in test or finishing a subtest. Previously they were called only after finishing the test clean up.

  • bpo-45034: Changes how error is formatted for struct.pack with 'H' and 'h' modes and too large / small numbers. Now it shows the actual numeric limits, while previously it was showing arithmetic expressions.

  • bpo-25894: unittest now always reports skipped and failed subtests separately: separate characters in default mode and separate lines in verbose mode. Also the test description is now output for errors in test method, class and module cleanups.

  • bpo-45081: Fix issue when dataclasses that inherit from typing.Protocol subclasses have wrong __init__. Patch provided by Yurii Karabas.

  • bpo-45085: The binhex module, deprecated in Python 3.9, is now removed. The following binascii functions, deprecated in Python 3.9, are now also removed:

    • a2b_hqx(), b2a_hqx();

    • rlecode_hqx(), rledecode_hqx().

    The binascii.crc_hqx() function remains available.

    Patch by Victor Stinner.

  • bpo-40360: The lib2to3 package is now deprecated and may not be able to parse Python 3.10 or newer. See the PEP 617 (New PEG parser for CPython). Patch by Victor Stinner.

  • bpo-45075: Rename traceback.StackSummary.format_frame() to traceback.StackSummary.format_frame_summary(). This method was added for 3.11 so it was not released yet.

    Updated code and docs to better distinguish frame and FrameSummary.

  • bpo-31299: Add option to completely drop frames from a traceback by returning None from a format_frame() override.

  • bpo-41620: run() now always return a TestResult instance. Previously it returned None if the test class or method was decorated with a skipping decorator.

  • bpo-45021: Fix a potential deadlock at shutdown of forked children when using concurrent.futures module

  • bpo-43913: Fix bugs in cleaning up classes and modules in unittest:

    • Functions registered with addModuleCleanup() were not called unless the user defines tearDownModule() in their test module.

    • Functions registered with addClassCleanup() were not called if tearDownClass is set to None.

    • Buffering in TestResult did not work with functions registered with addClassCleanup() and addModuleCleanup().

    • Errors in functions registered with addClassCleanup() and addModuleCleanup() were not handled correctly in buffered and debug modes.

    • Errors in setUpModule() and functions registered with addModuleCleanup() were reported in wrong order.

    • And several lesser bugs.

  • bpo-45030: Fix integer overflow in pickling and copying the range iterator.

  • bpo-45001: Made email date parsing more robust against malformed input, namely a whitespace-only Date: header. Patch by Wouter Bolsterlee.

  • bpo-45010: Remove support of special method __div__ in unittest.mock. It is not used in Python 3.

  • bpo-39218: Improve accuracy of variance calculations by using x*x instead of x**2.

  • bpo-43613: Improve the speed of gzip.compress() and gzip.decompress() by compressing and decompressing at once in memory instead of in a streamed fashion.

  • bpo-37596: Ensure that set and frozenset objects are always marshalled reproducibly.

  • bpo-44019: A new function operator.call has been added, such that operator.call(obj, *args, **kwargs) == obj(*args, **kwargs).

  • bpo-42255: webbrowser.MacOSX is deprecated and will be removed in Python 3.13. It is untested and undocumented and also not used by webbrowser itself. Patch by Donghee Na.

  • bpo-44955: Method stopTestRun() is now always called in pair with method startTestRun() for TestResult objects implicitly created in run(). Previously it was not called for test methods and classes decorated with a skipping decorator.

  • bpo-39039: tarfile.open raises ReadError when a zlib error occurs during file extraction.

  • bpo-44935: subprocess on Solaris now also uses os.posix_spawn() for better performance.

  • bpo-44911: IsolatedAsyncioTestCase will no longer throw an exception while cancelling leaked tasks. Patch by Bar Harel.

  • bpo-41322: Added DeprecationWarning for tests and async tests that return a value!=None (as this may indicate an improperly written test, for example a test written as a generator function).

  • bpo-44524: Make exception message more useful when subclass from typing special form alias. Patch provided by Yurii Karabas.

  • bpo-38956: argparse.BooleanOptionalAction’s default value is no longer printed twice when used with argparse.ArgumentDefaultsHelpFormatter.

  • bpo-44860: Fix the posix_user scheme in sysconfig to not depend on sys.platlibdir.

  • bpo-44859: Improve error handling in sqlite3 and raise more accurate exceptions.

    • MemoryError is now raised instead of sqlite3.Warning when memory is not enough for encoding a statement to UTF-8 in Connection.__call__() and Cursor.execute().

    • UnicodEncodeError is now raised instead of sqlite3.Warning when the statement contains surrogate characters in Connection.__call__() and Cursor.execute().

    • TypeError is now raised instead of ValueError for non-string script argument in Cursor.executescript().

    • ValueError is now raised for script containing the null character instead of truncating it in Cursor.executescript().

    • Correctly handle exceptions raised when getting boolean value of the result of the progress handler.

    • Add many tests covering different corner cases.

  • bpo-44581: Upgrade bundled pip to 21.2.3 and setuptools to 57.4.0

  • bpo-44849: Fix the os.set_inheritable() function on FreeBSD 14 for file descriptor opened with the O_PATH flag: ignore the EBADF error on ioctl(), fallback on the fcntl() implementation. Patch by Victor Stinner.

  • bpo-44605: The @functools.total_ordering() decorator now works with metaclasses.

  • bpo-44524: Fixed an issue wherein the __name__ and __qualname__ attributes of subscribed specialforms could be None.

  • bpo-44839: MemoryError raised in user-defined functions will now produce a MemoryError in sqlite3. OverflowError will now be converted to DataError. Previously OperationalError was produced in these cases.

  • bpo-44822: sqlite3 user-defined functions and aggregators returning strings with embedded NUL characters are no longer truncated. Patch by Erlend E. Aasland.

  • bpo-44801: Ensure that the ParamSpec variable in Callable can only be substituted with a parameters expression (a list of types, an ellipsis, ParamSpec or Concatenate).

  • bpo-44806: Non-protocol subclasses of typing.Protocol ignore now the __init__ method inherited from protocol base classes.

  • bpo-27275: collections.OrderedDict.popitem() and collections.OrderedDict.pop() no longer call __getitem__ and __delitem__ methods of the OrderedDict subclasses.

  • bpo-44793: Fix checking the number of arguments when subscribe a generic type with ParamSpec parameter.

  • bpo-44784: In importlib.metadata tests, override warnings behavior under expected DeprecationWarnings (importlib_metadata 4.6.3).

  • bpo-44667: The tokenize.tokenize() doesn’t incorrectly generate a NEWLINE token if the source doesn’t end with a new line character but the last line is a comment, as the function is already generating a NL token. Patch by Pablo Galindo

  • bpo-44771: Added importlib.simple module implementing adapters from a low-level resources reader interface to a TraversableResources interface. Legacy API (path, contents, …) is now supported entirely by the .files() API with a compatibility shim supplied for resource loaders without that functionality. Feature parity with importlib_resources 5.2.

  • bpo-44752: rcompleter does not call getattr() on property objects to avoid the side-effect of evaluating the corresponding method.

  • bpo-44747: Refactor usage of sys._getframe in typing module. Patch provided by Yurii Karabas.

  • bpo-42378: Fixes the issue with log file being overwritten when logging.FileHandler is used in atexit with filemode set to 'w'. Note this will cause the message in atexit not being logged if the log stream is already closed due to shutdown of logging.

  • bpo-44720: weakref.proxy objects referencing non-iterators now raise TypeError rather than dereferencing the null tp_iternext slot and crashing.

  • bpo-44704: The implementation of collections.abc.Set._hash() now matches that of frozenset.__hash__().

  • bpo-44666: Fixed issue in compileall.compile_file() when sys.stdout is redirected. Patch by Stefan Hölzl.

  • bpo-44688: sqlite3.Connection.create_collation() now accepts non-ASCII collation names. Patch by Erlend E. Aasland.

  • bpo-44690: Adopt binacii.a2b_base64’s strict mode in base64.b64decode.

  • bpo-42854: Fixed a bug in the _ssl module that was throwing OverflowError when using _ssl._SSLSocket.write() and _ssl._SSLSocket.read() for a big value of the len parameter. Patch by Pablo Galindo

  • bpo-44686: Replace unittest.mock._importer with pkgutil.resolve_name.

  • bpo-44353: Make NewType.__call__ faster by implementing it in C. Patch provided by Yurii Karabas.

  • bpo-44682: Change the pdb commands directive to disallow setting commands for an invalid breakpoint and to display an appropriate error.

  • bpo-44353: Refactor typing.NewType from function into callable class. Patch provided by Yurii Karabas.

  • bpo-44678: Added a separate error message for discontinuous padding in binascii.a2b_base64 strict mode.

  • bpo-44524: Add missing __name__ and __qualname__ attributes to typing module classes. Patch provided by Yurii Karabas.

  • bpo-40897: Give priority to using the current class constructor in inspect.signature(). Patch by Weipeng Hong.

  • bpo-44638: Add a reference to the zipp project and hint as to how to use it.

  • bpo-44648: Fixed wrong error being thrown by inspect.getsource() when examining a class in the interactive session. Instead of TypeError, it should be OSError with appropriate error message.

  • bpo-44608: Fix memory leak in _tkinter._flatten() if it is called with a sequence or set, but not list or tuple.

  • bpo-44594: Fix an edge case of ExitStack and AsyncExitStack exception chaining. They will now match with block behavior when __context__ is explicitly set to None when the exception is in flight.

  • bpo-42799: In fnmatch, the cache size for compiled regex patterns (functools.lru_cache()) was bumped up from 256 to 32768, affecting functions: fnmatch.fnmatch(), fnmatch.fnmatchcase(), fnmatch.filter().

  • bpo-41928: Update shutil.copyfile() to raise FileNotFoundError instead of confusing IsADirectoryError when a path ending with a os.path.sep does not exist; shutil.copy() and shutil.copy2() are also affected.

  • bpo-44569: Added the StackSummary.format_frame() function in traceback. This allows users to customize the way individual lines are formatted in tracebacks without re-implementing logic to handle recursive tracebacks.

  • bpo-44566: handle StopIteration subclass raised from @contextlib.contextmanager generator

  • bpo-44558: Make the implementation consistency of indexOf() between C and Python versions. Patch by Donghee Na.

  • bpo-41249: Fixes TypedDict to work with typing.get_type_hints() and postponed evaluation of annotations across modules.

  • bpo-44554: Refactor argument processing in pdb.main() to simplify detection of errors in input loading and clarify behavior around module or script invocation.

  • bpo-34798: Break up paragraph about pprint.PrettyPrinter construction parameters to make it easier to read.

  • bpo-44539: Added support for recognizing JPEG files without JFIF or Exif markers.

  • bpo-44461: Fix bug with pdb’s handling of import error due to a package which does not have a __main__ module

  • bpo-43625: Fix a bug in the detection of CSV file headers by csv.Sniffer.has_header() and improve documentation of same.

  • bpo-44516: Update vendored pip to 21.1.3

  • bpo-42892: Fixed an exception thrown while parsing a malformed multipart email by email.message.EmailMessage.

  • bpo-44468: typing.get_type_hints() now finds annotations in classes and base classes with unexpected __module__. Previously, it skipped those MRO elements.

  • bpo-44491: Allow clearing the sqlite3 authorizer callback by passing None to set_authorizer(). Patch by Erlend E. Aasland.

  • bpo-43977: Set the proper Py_TPFLAGS_MAPPING and Py_TPFLAGS_SEQUENCE flags for subclasses created before a parent has been registered as a collections.abc.Mapping or collections.abc.Sequence.

  • bpo-44482: Fix very unlikely resource leak in glob in alternate Python implementations.

  • bpo-44466: The faulthandler module now detects if a fatal error occurs during a garbage collector collection. Patch by Victor Stinner.

  • bpo-44471: A TypeError is now raised instead of an AttributeError in contextlib.ExitStack.enter_context() and contextlib.AsyncExitStack.enter_async_context() for objects which do not support the context manager or asynchronous context manager protocols correspondingly.

  • bpo-44404: tkinter’s after() method now supports callables without the __name__ attribute.

  • bpo-41546: Make pprint (like the builtin print) not attempt to write to stdout when it is None.

  • bpo-44458: BUFFER_BLOCK_SIZE is now declared static, to avoid linking collisions when bz2, lmza or zlib are statically linked.

  • bpo-44464: Remove exception for flake8 in deprecated importlib.metadata interfaces. Sync with importlib_metadata 4.6.

  • bpo-44446: Take into account that lineno might be None in traceback.FrameSummary.

  • bpo-44439: Fix in bz2.BZ2File.write() / lzma.LZMAFile.write() methods, when the input data is an object that supports the buffer protocol, the file length may be wrong.

  • bpo-44434: _thread.start_new_thread() no longer calls PyThread_exit_thread() explicitly at the thread exit, the call was redundant. On Linux with the glibc, pthread_exit() aborts the whole process if dlopen() fails to open libgcc_s.so file (ex: EMFILE error). Patch by Victor Stinner.

  • bpo-42972: The _thread.RLock type now fully implement the GC protocol: add a traverse function and the Py_TPFLAGS_HAVE_GC flag. Patch by Victor Stinner.

  • bpo-44422: The threading.enumerate() function now uses a reentrant lock to prevent a hang on reentrant call. Patch by Victor Stinner.

  • bpo-38291: Importing typing.io or typing.re now prints a DeprecationWarning.

  • bpo-37880: argparse actions store_const and append_const each receive a default value of None when the const kwarg is not provided. Previously, this raised a TypeError.

  • bpo-44389: Fix deprecation of ssl.OP_NO_TLSv1_3

  • bpo-27827: pathlib.PureWindowsPath.is_reserved() now identifies a greater range of reserved filenames, including those with trailing spaces or colons.

  • bpo-44395: Fix as_string() to pass unixfrom properly. Patch by Donghee Na.

  • bpo-34266: Handle exceptions from parsing the arg of pdb’s run/restart command.

  • bpo-44362: Improve ssl module’s deprecation messages, error reporting, and documentation for deprecations.

  • bpo-44342: [Enum] Change pickling from by-value to by-name.

  • bpo-44356: [Enum] Allow multiple data-type mixins if they are all the same.

  • bpo-44351: Restore back parse_makefile() in distutils.sysconfig because it behaves differently than the similar implementation in sysconfig.

  • bpo-35800: smtpd.MailmanProxy is now removed as it is unusable without an external module, mailman. Patch by Donghee Na.

  • bpo-44357: Added a function that returns cube root of the given number math.cbrt()

  • bpo-44339: Change math.pow(±0.0, -math.inf) to return inf instead of raising ValueError. This brings the special-case handling of math.pow into compliance with the IEEE 754 standard.

  • bpo-44242: Remove missing flag check from Enum creation and move into a verify decorator.

  • bpo-44246: In importlib.metadata, restore compatibility in the result from Distribution.entry_points (EntryPoints) to honor expectations in older implementations and issuing deprecation warnings for these cases: A. EntryPoints objects are once again mutable, allowing for sort() and other list-based mutation operations. Avoid deprecation warnings by casting to a mutable sequence (e.g. list(dist.entry_points).sort()). B. EntryPoints results once again allow for access by index. To avoid deprecation warnings, cast the result to a Sequence first (e.g. tuple(dist.entry_points)[0]).

  • bpo-44246: In importlib.metadata.entry_points, de-duplication of distributions no longer requires loading the full metadata for PathDistribution objects, improving entry point loading performance by ~10x.

  • bpo-43858: Added a function that returns a copy of a dict of logging levels: logging.getLevelNamesMapping()

  • bpo-44260: The random.Random constructor no longer reads system entropy without need.

  • bpo-44254: On Mac, give turtledemo button text a color that works on both light or dark background. Programmers cannot control the latter.

  • bpo-44258: Support PEP 515 for Fraction’s initialization from string.

  • bpo-44235: Remove deprecated functions in the gettext. Patch by Donghee Na.

  • bpo-38693: Prefer f-strings to .format in importlib.resources.

  • bpo-33693: Importlib.metadata now prefers f-strings to .format.

  • bpo-44241: Incorporate minor tweaks from importlib_metadata 4.1: SimplePath protocol, support for Metadata 2.2.

  • bpo-43216: Remove the @asyncio.coroutine decorator enabling legacy generator-based coroutines to be compatible with async/await code; remove asyncio.coroutines.CoroWrapper used for wrapping legacy coroutine objects in the debug mode. The decorator has been deprecated since Python 3.8 and the removal was initially scheduled for Python 3.10. Patch by Illia Volochii.

  • bpo-44210: Make importlib.metadata._meta.PackageMetadata public.

  • bpo-43643: Declare readers.MultiplexedPath.name as a property per the spec.

  • bpo-27334: The sqlite3 context manager now performs a rollback (thus releasing the database lock) if commit failed. Patch by Luca Citi and Erlend E. Aasland.

  • bpo-4928: Documented existing behavior on POSIX: NamedTemporaryFiles are not deleted when creating process is killed with SIGKILL

  • bpo-44154: Optimize fractions.Fraction pickling for large components.

  • bpo-33433: For IPv4 mapped IPv6 addresses (RFC 4291 Section 2.5.5.2), the ipaddress.IPv6Address.is_private check is deferred to the mapped IPv4 address. This solves a bug where public mapped IPv4 addresses were considered private by the IPv6 check.

  • bpo-44150: Add optional weights argument to statistics.fmean().

  • bpo-44142: ast.unparse() will now drop the redundant parentheses when tuples used as assignment targets (e.g in for loops).

  • bpo-44145: hmac computations were not releasing the GIL while calling the OpenSSL HMAC_Update C API (a new feature in 3.9). This unintentionally prevented parallel computation as other hashlib algorithms support.

  • bpo-44095: zipfile.Path now supports zipfile.Path.stem, zipfile.Path.suffixes, and zipfile.Path.suffix attributes.

  • bpo-44077: It’s now possible to receive the type of service (ToS), a.k.a. differentiated services (DS), a.k.a. differentiated services code point (DSCP) and explicit congestion notification (ECN) IP header fields with socket.IP_RECVTOS.

  • bpo-37788: Fix a reference leak when a Thread object is never joined.

  • bpo-38908: Subclasses of typing.Protocol which only have data variables declared will now raise a TypeError when checked with isinstance unless they are decorated with runtime_checkable(). Previously, these checks passed silently. Patch provided by Yurii Karabas.

  • bpo-44098: typing.ParamSpec will no longer be found in the __parameters__ of most typing generics except in valid use locations specified by PEP 612. This prevents incorrect usage like typing.List[P][int]. This change means incorrect usage which may have passed silently in 3.10 beta 1 and earlier will now error.

  • bpo-44089: Allow subclassing csv.Error in 3.10 (it was allowed in 3.9 and earlier but was disallowed in early versions of 3.10).

  • bpo-44081: ast.unparse() now doesn’t use redundant spaces to separate lambda and the : if there are no parameters.

  • bpo-44061: Fix regression in previous release when calling pkgutil.iter_modules() with a list of pathlib.Path objects

  • bpo-44059: Register the SerenityOS Browser in the webbrowser module.

  • bpo-36515: The hashlib module no longer does unaligned memory accesses when compiled for ARM platforms.

  • bpo-40465: Remove random module features deprecated in Python 3.9.

  • bpo-44018: random.seed() no longer mutates bytearray inputs.

  • bpo-38352: Add IO, BinaryIO, TextIO, Match, and Pattern to typing.__all__. Patch by Jelle Zijlstra.

  • bpo-44002: urllib.parse now uses functool.lru_cache() for its internal URL splitting and quoting caches instead of rolling its own like its the ’90s.

    The undocumented internal urllib.parse Quoted class API is now deprecated, for removal in 3.14.

  • bpo-43972: When http.server.SimpleHTTPRequestHandler sends a 301 (Moved Permanently) for a directory path not ending with /, add a Content-Length: 0 header. This improves the behavior for certain clients.

  • bpo-28528: Fix a bug in pdb where checkline() raises AttributeError if it is called after reset().

  • bpo-43853: Improved string handling for sqlite3 user-defined functions and aggregates:

    • It is now possible to pass strings with embedded null characters to UDFs

    • Conversion failures now correctly raise MemoryError

    Patch by Erlend E. Aasland.

  • bpo-43666: AIX: Lib/_aix_support.get_platform() may fail in an AIX WPAR. The fileset bos.rte appears to have a builddate in both LPAR and WPAR so this fileset is queried rather than bos.mp64. To prevent a similar situation (no builddate in ODM) a value (9988) sufficient for completing a build is provided. Patch by M Felt.

  • bpo-43650: Fix MemoryError in shutil.unpack_archive() which fails inside shutil._unpack_zipfile() on large files. Patch by Igor Bolshakov.

  • bpo-43612: zlib.compress() now accepts a wbits parameter which allows users to compress data as a raw deflate block without zlib headers and trailers in one go. Previously this required instantiating a zlib.compressobj. It also provides a faster alternative to gzip.compress when wbits=31 is used.

  • bpo-43392: importlib._bootstrap._find_and_load() now implements a two-step check to avoid locking when modules have been already imported and are ready. This improves performance of repeated calls to importlib.import_module() and importlib.__import__().

  • bpo-43318: Fix a bug where pdb does not always echo cleared breakpoints.

  • bpo-43234: Prohibit passing non-concurrent.futures.ThreadPoolExecutor executors to loop.set_default_executor() following a deprecation in Python 3.8. Patch by Illia Volochii.

  • bpo-43232: Prohibit previously deprecated potentially disruptive operations on asyncio.trsock.TransportSocket. Patch by Illia Volochii.

  • bpo-30077: Added support for Apple’s aifc/sowt pseudo-compression

  • bpo-42971: Add definition of errno.EQFULL for platforms that define this constant (such as macOS).

  • bpo-43086: Added a new optional strict_mode parameter to binascii.a2b_base64. When scrict_mode is set to True, the a2b_base64 function will accept only valid base64 content. More details about what “valid base64 content” is, can be found in the function’s documentation.

  • bpo-43024: Improve the help signature of traceback.print_exception(), traceback.format_exception() and traceback.format_exception_only().

  • bpo-33809: Add the traceback.TracebackException.print() method which prints the formatted exception information.

  • bpo-42862: sqlite3 now utilizes functools.lru_cache() to implement the connection statement cache. As a small optimisation, the default statement cache size has been increased from 100 to 128. Patch by Erlend E. Aasland.

  • bpo-41818: Soumendra Ganguly: add termios.tcgetwinsize(), termios.tcsetwinsize().

  • bpo-40497: subprocess.check_output() now raises ValueError when the invalid keyword argument check is passed by user code. Previously such use would fail later with a TypeError. Patch by Rémi Lapeyre.

  • bpo-37449: ensurepip now uses importlib.resources.files() traversable APIs

  • bpo-40956: Use Argument Clinic in sqlite3. Patches by Erlend E. Aasland.

  • bpo-41730: DeprecationWarning is now raised when importing tkinter.tix, which has been deprecated in documentation since Python 3.6.

  • bpo-20684: Remove unused _signature_get_bound_param function from inspect - by Anthony Sottile.

  • bpo-41402: Fix email.message.EmailMessage.set_content() when called with binary data and 7bit content transfer encoding.

  • bpo-32695: The compresslevel and preset keyword arguments of tarfile.open() are now both documented and tested.

  • bpo-41137: Use utf-8 encoding while reading .pdbrc files. Patch by Srinivas Reddy Thatiparthy

  • bpo-24391: Improved reprs of threading synchronization objects: Semaphore, BoundedSemaphore, Event and Barrier.

  • bpo-5846: Deprecated the following unittest functions, scheduled for removal in Python 3.13:

    • findTestCases()

    • makeSuite()

    • getTestCaseNames()

    Use TestLoader methods instead:

    Patch by Erlend E. Aasland.

  • bpo-40563: Support pathlike objects on dbm/shelve. Patch by Hakan Çelik and Henry-Joseph Audéoud.

  • bpo-34990: Fixed a Y2k38 bug in the compileall module where it would fail to compile files with a modification time after the year 2038.

  • bpo-39549: Whereas the code for reprlib.Repr had previously used a hardcoded string value of ‘…’, this PR updates it to use of a “fillvalue” attribute, whose value defaults to ‘…’ and can be reset in either individual reprlib.Repr instances or in subclasses thereof.

  • bpo-37022: pdb now displays exceptions from repr() with its p and pp commands.

  • bpo-38840: Fix test___all__ on platforms lacking a shared memory implementation.

  • bpo-39359: Add one missing check that the password is a bytes object for an encrypted zipfile.

  • bpo-38741: configparser: using ‘]’ inside a section header will no longer cut the section name short at the ‘]’

  • bpo-38415: Added missing behavior to contextlib.asynccontextmanager() to match contextlib.contextmanager() so decorated functions can themselves be decorators.

  • bpo-30256: Pass multiprocessing BaseProxy argument manager_owned through AutoProxy.

  • bpo-27513: email.utils.getaddresses() now accepts email.header.Header objects along with string values. Patch by Zackery Spytz.

  • bpo-16379: Add SQLite error code and name to sqlite3 exceptions. Patch by Aviv Palivoda, Daniel Shahaf, and Erlend E. Aasland.

  • bpo-26228: pty.spawn no longer hangs on FreeBSD, macOS, and Solaris.

  • bpo-33349: lib2to3 now recognizes async generators everywhere.

  • bpo-29298: Fix TypeError when required subparsers without dest do not receive arguments. Patch by Anthony Sottile.

Documentation

  • bpo-45216: Remove extra documentation listing methods in difflib. It was rendering twice in pydoc and was outdated in some places.

  • bpo-45024: collections.abc documentation has been expanded to explicitly cover how instance and subclass checks work, with additional doctest examples and an exhaustive list of ABCs which test membership purely by presence of the right special methods. Patch by Raymond Hettinger.

  • bpo-44957: Promote PEP 604 union syntax by using it where possible. Also, mention X | Y more prominently in section about Union and mention X | None at all in section about Optional.

  • bpo-16580: Added code equivalents for the int.to_bytes() and int.from_bytes() methods, as well as tests ensuring that these code equivalents are valid.

  • bpo-44903: Removed the othergui.rst file, any references to it, and the list of GUI frameworks in the FAQ. In their place I’ve added links to the Python Wiki page on GUI frameworks.

  • bpo-33479: Tkinter documentation has been greatly expanded with new “Architecture” and “Threading model” sections.

  • bpo-36700: base64 RFC references were updated to point to RFC 4648; a section was added to point users to the new “security considerations” section of the RFC.

  • bpo-44740: Replaced occurrences of uppercase “Web” and “Internet” with lowercase versions per the 2016 revised Associated Press Style Book.

  • bpo-44693: Update the definition of __future__ in the glossary by replacing the confusing word “pseudo-module” with a more accurate description.

  • bpo-35183: Add typical examples to os.path.splitext docs

  • bpo-30511: Clarify that shutil.make_archive() is not thread-safe due to reliance on changing the current working directory.

  • bpo-44561: Update of three expired hyperlinks in Doc/distributing/index.rst: “Project structure”, “Building and packaging the project”, and “Uploading the project to the Python Packaging Index”.

  • bpo-44651: Delete entry “coercion” in Doc/glossary.rst for its outdated definition.

  • bpo-42958: Updated the docstring and docs of filecmp.cmp() to be more accurate and less confusing especially in respect to shallow arg.

  • bpo-44631: Refactored the repr() code of the _Environ (os module).

  • bpo-44613: importlib.metadata is no longer provisional.

  • bpo-44558: Match the docstring and python implementation of countOf() to the behavior of its c implementation.

  • bpo-44544: List all kwargs for textwrap.wrap(), textwrap.fill(), and textwrap.shorten(). Now, there are nav links to attributes of TextWrap, which makes navigation much easier while minimizing duplication in the documentation.

  • bpo-38062: Clarify that atexit uses equality comparisons internally.

  • bpo-40620: Convert examples in tutorial controlflow.rst section 4.3 to be interpreter-demo style.

  • bpo-43066: Added a warning to zipfile docs: filename arg with a leading slash may cause archive to be un-openable on Windows systems.

  • bpo-39452: Rewrote Doc/library/__main__.rst. Broadened scope of the document to explicitly discuss and differentiate between __main__.py in packages versus the __name__ == '__main__' expression (and the idioms that surround it).

  • bpo-13814: In the Design FAQ, answer “Why don’t generators support the with statement?”

  • bpo-27752: Documentation of csv.Dialect is more descriptive.

  • bpo-44453: Fix documentation for the return type of sysconfig.get_path().

  • bpo-44392: Added a new section in the C API documentation for types used in type hinting. Documented Py_GenericAlias and Py_GenericAliasType.

  • bpo-38291: Mark typing.io and typing.re as deprecated since Python 3.8 in the documentation. They were never properly supported by type checkers.

  • bpo-44322: Document that SyntaxError args have a details tuple and that details are adjusted for errors in f-string field replacement expressions.

  • bpo-42392: Document the deprecation and removal of the loop parameter for many functions and classes in asyncio.

  • bpo-44195: Corrected references to TraversableResources in docs. There is no TraversableReader.

  • bpo-41963: Document that ConfigParser strips off comments when reading configuration files.

  • bpo-44072: Correct where in the numeric ABC hierarchy ** support is added, i.e., in numbers.Complex, not numbers.Integral.

  • bpo-43558: Add the remark to dataclasses documentation that the __init__() of any base class has to be called in __post_init__(), along with a code example.

  • bpo-44025: Clarify when ‘_’ in match statements is a keyword, and when not.

  • bpo-41706: Fix docs about how methods like __add__ are invoked when evaluating operator expressions.

  • bpo-41621: Document that collections.defaultdict parameter default_factory defaults to None and is positional-only.

  • bpo-41576: document BaseException in favor of bare except

  • bpo-21760: The description for __file__ fixed. Patch by Furkan Onder

  • bpo-39498: Add a “Security Considerations” index which links to standard library modules that have explicitly documented security considerations.

  • bpo-33479: Remove the unqualified claim that tkinter is threadsafe. It has not been true for several years and likely never was. An explanation of what is true may be added later, after more discussion, and possibly after patching _tkinter.c,

Tests

  • bpo-40173: Fix test.support.import_helper.import_fresh_module().

  • bpo-45280: Add a test case for empty typing.NamedTuple.

  • bpo-45269: Cover case when invalid markers type is supplied to c_make_encoder.

  • bpo-45128: Fix test_multiprocessing_fork failure due to test_logging and sys.modules manipulation.

  • bpo-45209: Fix UserWarning: resource_tracker warning in _test_multiprocessing._TestSharedMemory.test_shared_memory_cleaned_after_process_termination

  • bpo-45185: Enables TestEnumerations test cases in test_ssl suite.

  • bpo-45195: Fix test_readline.test_nonascii(): sometimes, the newline character is not written at the end, so don’t expect it in the output. Patch by Victor Stinner.

  • bpo-45156: Fixes infinite loop on unittest.mock.seal() of mocks created by create_autospec().

  • bpo-45125: Improves pickling tests and docs of SharedMemory and SharableList objects.

  • bpo-44860: Update test_sysconfig.test_user_similar() for the posix_user scheme: platlib doesn’t use sys.platlibdir. Patch by Victor Stinner.

  • bpo-45052: WithProcessesTestSharedMemory.test_shared_memory_basics test was ignored, because self.assertEqual(sms.size, sms2.size) line was failing. It is now removed and test is unskipped.

    The main motivation for this line to be removed from the test is that the size of SharedMemory is not ever guaranteed to be the same. It is decided by the platform.

  • bpo-44895: libregrtest now clears the type cache later to reduce the risk of false alarm when checking for reference leaks. Previously, the type cache was cleared too early and libregrtest raised a false alarm about reference leaks under very specific conditions. Patch by Irit Katriel and Victor Stinner.

  • bpo-45042: Fixes that test classes decorated with @hashlib_helper.requires_hashdigest were skipped all the time.

  • bpo-25130: Add calls of gc.collect() in tests to support PyPy.

  • bpo-45011: Made tests relying on the _asyncio C extension module optional to allow running on alternative Python implementations. Patch by Serhiy Storchaka.

  • bpo-44949: Fix auto history tests of test_readline: sometimes, the newline character is not written at the end, so don’t expect it in the output.

  • bpo-44891: Tests were added to clarify id() is preserved when obj * 1 is used on str and bytes objects. Patch by Nikita Sobolev.

  • bpo-44852: Add ability to wholesale silence DeprecationWarnings while running the regression test suite.

  • bpo-40928: Notify users running test_decimal regression tests on macOS of potential harmless “malloc can’t allocate region” messages spewed by test_decimal.

  • bpo-44734: Fixed floating point precision issue in turtle tests.

  • bpo-44708: Regression tests, when run with -w, are now re-running only the affected test methods instead of re-running the entire test file.

  • bpo-42095: Added interop tests for Apple plists: generate plist files with Python plistlib and parse with Apple plutil; and the other way round.

  • bpo-44647: Added a permanent Unicode-valued environment variable to regression tests to ensure they handle this use case in the future. If your test environment breaks because of that, report a bug to us, and temporarily set PYTHONREGRTEST_UNICODE_GUARD=0 in your test environment.

  • bpo-44515: Adjust recently added contextlib tests to avoid assuming the use of a refcounted GC

  • bpo-44287: Fix asyncio test_popen() of test_windows_utils by using a longer timeout. Use military grade battle-tested test.support.SHORT_TIMEOUT timeout rather than a hardcoded timeout of 10 seconds: it’s 30 seconds by default, but it is made longer on slow buildbots. Patch by Victor Stinner.

  • bpo-44451: Reset DeprecationWarning filters in test.test_importlib.test_metadata_api.APITests.test_entry_points_by_index to avoid StopIteration error if DeprecationWarnings are ignored.

  • bpo-44363: Account for address sanitizer in test_capi. test_capi now passes when run GCC address sanitizer.

  • bpo-44364: Add non integral tests for math.sqrt() function.

  • bpo-43921: Fix test_ssl.test_wrong_cert_tls13(): use suppress_ragged_eofs=False, since read() can raise ssl.SSLEOFError on Windows. Patch by Victor Stinner.

  • bpo-43921: Fix test_pha_required_nocert() of test_ssl: catch two more EOF cases (when the recv() method returns an empty string). Patch by Victor Stinner.

  • bpo-44131: Add test_frozenmain to test_embed to test the Py_FrozenMain() C function. Patch by Victor Stinner.

  • bpo-31904: Ignore error string case in test_file_not_exists().

  • bpo-42083: Add test to check that PyStructSequence_NewType accepts a PyStructSequence_Desc with doc field set to NULL.

  • bpo-35753: Fix crash in doctest when doctest parses modules that include unwrappable functions by skipping those functions.

  • bpo-30256: Add test for nested queues when using multiprocessing shared objects AutoProxy[Queue] inside ListProxy and DictProxy

Build

  • bpo-45220: Avoid building with the Windows 11 SDK previews automatically. This may be overridden by setting the DefaultWindowsSDKVersion environment variable before building.

  • bpo-45020: Freeze stdlib modules that are imported during startup. This provides significant performance improvements to startup. If necessary, use the previously added “-X frozen_modules=off” commandline option to force importing the source modules.

  • bpo-45188: Windows builds now regenerate frozen modules as the first part of the build. Previously the regeneration was later in the build, which would require it to be restarted if any modules had changed.

  • bpo-45163: Fixes Haiku platform build.

  • bpo-45067: The ncurses function extended_color_content was introduced in 2017

    (https://invisible-island.net/ncurses/NEWS.html#index-t20170401). The

    ncurses-devel package in CentOS 7 had a older version ncurses resulted in compilation error. For compiling ncurses with extended color support, we verify the version of the ncurses library >= 20170401.

  • bpo-45019: Generate lines in relevant files for frozen modules. Up until now each of the files had to be edited manually. This change makes it easier to add to and modify the frozen modules.

  • bpo-44340: Add support for building with clang thin lto via –with-lto=thin/full. Patch by Donghee Na and Brett Holman.

  • bpo-44535: Enable building using a Visual Studio 2022 install on Windows.

  • bpo-43298: Improved error message when building without a Windows SDK installed.

  • bpo-44381: The Windows build now accepts EnableControlFlowGuard set to guard to enable CFG.

  • bpo-41282: Fix broken make install that caused standard library extension modules to be unnecessarily and incorrectly rebuilt during the install phase of cpython.

Windows

macOS

  • bpo-45007: Update macOS installer builds to use OpenSSL 1.1.1l.

  • bpo-34602: When building CPython on macOS with ./configure --with-undefined-behavior-sanitizer --with-pydebug, the stack size is now quadrupled to allow for the entire test suite to pass.

  • bpo-44848: Update macOS installer to use SQLite 3.36.0.

  • bpo-44689: ctypes.util.find_library() now works correctly on macOS 11 Big Sur even if Python is built on an older version of macOS. Previously, when built on older macOS systems, find_library was not able to find macOS system libraries when running on Big Sur due to changes in how system libraries are stored.

  • bpo-41972: The framework build’s user header path in sysconfig is changed to add a ‘pythonX.Y’ component to match distutils’s behavior.

  • bpo-43109: Allow –with-lto configure option to work with Apple-supplied Xcode or Command Line Tools.

  • bpo-34932: Add socket.TCP_KEEPALIVE support for macOS. Patch by Shane Harvey.

IDLE

  • bpo-45296: On Windows, change exit/quit message to suggest Ctrl-D, which works, instead of <Ctrl-Z Return>, which does not work in IDLE.

  • bpo-45193: Make completion boxes appear on Ubuntu again.

  • bpo-40128: Mostly fix completions on macOS when not using tcl/tk 8.6.11 (as with 3.9). The added update_idletask call should be harmless and possibly helpful otherwise.

  • bpo-33962: Move the indent space setting from the Font tab to the new Windows tab. Patch by Mark Roseman and Terry Jan Reedy.

  • bpo-40468: Split the settings dialog General tab into Windows and Shell/ED tabs. Move help sources, which extend the Help menu, to the Extensions tab. Make space for new options and shorten the dialog. The latter makes the dialog better fit small screens.

  • bpo-41611: Avoid uncaught exceptions in AutoCompleteWindow.winconfig_event().

  • bpo-41611: Fix IDLE sometimes freezing upon tab-completion on macOS.

  • bpo-44010: Highlight the new match statement’s soft keywords: match, case, and _. However, this highlighting is not perfect and will be incorrect in some rare cases, including some _-s in case patterns.

  • bpo-44026: Include interpreter’s typo fix suggestions in message line for NameErrors and AttributeErrors. Patch by E. Paine.

Tools/Demos

  • bpo-44786: Fix a warning in regular expression in the c-analyzer script.

  • bpo-44967: pydoc now returns a non-zero status code when a module cannot be found.

  • bpo-44978: Allow the Argument Clinic tool to handle __complex__ special methods.

  • bpo-43425: Removed the ‘test2to3’ demo project that demonstrated using lib2to3 to support Python 2.x and Python 3.x from a single source in a distutils package. Patch by Donghee Na

  • bpo-44074: Make patchcheck automatically detect the correct base branch name (previously it was hardcoded to ‘master’)

  • bpo-20291: Added support for variadic positional parameters in Argument Clinic.

C API

  • bpo-41710: The PyThread_acquire_lock_timed() function now clamps the timeout if it is too large, rather than aborting the process. Patch by Victor Stinner.

  • bpo-44687: BufferedReader.peek() no longer raises ValueError when the entire file has already been buffered.

  • bpo-45116: Add the Py_ALWAYS_INLINE macro to ask the compiler to always inline a static inline function. The compiler can ignore it and decides to not inline the function. Patch by Victor Stinner.

  • bpo-45094: Add the Py_NO_INLINE macro to disable inlining on a function. Patch by Victor Stinner.

  • bpo-45061: Add a deallocator to the bool type to detect refcount bugs in C extensions which call Py_DECREF(Py_True); or Py_DECREF(Py_False); by mistake. Patch by Victor Stinner.

  • bpo-42035: Add a new PyType_GetQualName() function to get type’s qualified name.

  • bpo-41103: Reverts removal of the old buffer protocol because they are part of stable ABI.

  • bpo-44751: Remove crypt.h include from the public Python.h header.

  • bpo-42747: The Py_TPFLAGS_HAVE_VERSION_TAG type flag now does nothing. The Py_TPFLAGS_HAVE_AM_SEND flag (which was added in 3.10) is removed. Both were unnecessary because it is not possible to have type objects with the relevant fields missing.

  • bpo-44530: Added the co_qualname to the PyCodeObject structure to propagate the qualified name from the compiler to code objects.

    Patch by Gabriele N. Tornetta

  • bpo-44441: Py_RunMain() now resets PyImport_Inittab to its initial value at exit. It must be possible to call PyImport_AppendInittab() or PyImport_ExtendInittab() at each Python initialization. Patch by Victor Stinner.

  • bpo-39947: Remove 4 private trashcan C API functions which were only kept for the backward compatibility of the stable ABI with Python 3.8 and older, since the trashcan API was not usable with the limited C API on Python 3.8 and older. The trashcan API was excluded from the limited C API in Python 3.9.

    Removed functions:

    • _PyTrash_deposit_object()

    • _PyTrash_destroy_chain()

    • _PyTrash_thread_deposit_object()

    • _PyTrash_thread_destroy_chain()

    The trashcan C API was never usable with the limited C API, since old trashcan macros accessed directly PyThreadState members like _tstate->trash_delete_nesting, whereas the PyThreadState structure is opaque in the limited C API.

    Exclude also the PyTrash_UNWIND_LEVEL constant from the C API.

    Patch by Victor Stinner.

  • bpo-40939: Removed documentation for the removed PyParser_* C API.

  • bpo-43795: The list in Contents of Limited API now shows the public name PyFrameObject rather than _frame. The non-existing entry _node no longer appears in the list.

  • bpo-44378: Py_IS_TYPE() no longer uses Py_TYPE() to avoid a compiler warning: no longer cast const PyObject* to PyObject*. Patch by Victor Stinner.

  • bpo-39573: Convert the Py_TYPE() and Py_SIZE() macros to static inline functions. The Py_SET_TYPE() and Py_SET_SIZE() functions must now be used to set an object type and size. Patch by Victor Stinner.

  • bpo-44263: The PyType_Ready() function now raises an error if a type is defined with the Py_TPFLAGS_HAVE_GC flag set but has no traverse function (PyTypeObject.tp_traverse). Patch by Victor Stinner.

  • bpo-43795: The undocumented function Py_FrozenMain() is removed from the Limited API.

  • bpo-44113: Deprecate the following functions to configure the Python initialization:

    • PySys_AddWarnOptionUnicode()

    • PySys_AddWarnOption()

    • PySys_AddXOption()

    • PySys_HasWarnOptions()

    • Py_SetPath()

    • Py_SetProgramName()

    • Py_SetPythonHome()

    • Py_SetStandardStreamEncoding()

    • _Py_SetProgramFullPath()

    Use the new PyConfig API of the Python Initialization Configuration instead (PEP 587).

  • bpo-44094: Remove PyErr_SetFromErrnoWithUnicodeFilename(), PyErr_SetFromWindowsErrWithUnicodeFilename(), and PyErr_SetExcFromWindowsErrWithUnicodeFilename(). They are not documented and have been deprecated since Python 3.3.

  • bpo-43795: PyCodec_Unregister() is now properly exported as a function in the Windows Stable ABI DLL.

  • bpo-44029: Remove deprecated Py_UNICODE APIs: PyUnicode_Encode, PyUnicode_EncodeUTF7, PyUnicode_EncodeUTF8, PyUnicode_EncodeUTF16, PyUnicode_EncodeUTF32, PyUnicode_EncodeLatin1, PyUnicode_EncodeMBCS, PyUnicode_EncodeDecimal, PyUnicode_EncodeRawUnicodeEscape, PyUnicode_EncodeCharmap, PyUnicode_EncodeUnicodeEscape, PyUnicode_TransformDecimalToASCII, PyUnicode_TranslateCharmap, PyUnicodeEncodeError_Create, PyUnicodeTranslateError_Create. See PEP 393 and PEP 624 for reference.

  • bpo-42035: Add a new PyType_GetName() function to get type’s short name.

Python 3.10.0 beta 1

Release date: 2021-05-03

Security

  • bpo-43434: Creating sqlite3.Connection objects now also produces sqlite3.connect and sqlite3.connect/handle auditing events. Previously these events were only produced by sqlite3.connect() calls. Patch by Erlend E. Aasland.

  • bpo-43998: The ssl module sets more secure cipher suites defaults. Ciphers without forward secrecy and with SHA-1 MAC are disabled by default. Security level 2 prohibits weak RSA, DH, and ECC keys with less than 112 bits of security. SSLContext defaults to minimum protocol version TLS 1.2. Settings are based on Hynek Schlawack’s research.

  • bpo-43882: The presence of newline or tab characters in parts of a URL could allow some forms of attacks.

    Following the controlling specification for URLs defined by WHATWG urllib.parse() now removes ASCII newlines and tabs from URLs, preventing such attacks.

  • bpo-43472: Ensures interpreter-level audit hooks receive the cpython.PyInterpreterState_New event when called through the _xxsubinterpreters module.

  • bpo-43362: Fix invalid free in _sha3 module. The issue was introduced in 3.10.0a1. Python 3.9 and earlier are not affected.

  • bpo-43762: Add audit events for sqlite3.connect/handle(), sqlite3.Connection.enable_load_extension(), and sqlite3.Connection.load_extension(). Patch by Erlend E. Aasland.

  • bpo-43756: Add new audit event glob.glob/2 to incorporate the new root_dir and dir_fd arguments added to glob.glob() and glob.iglob().

  • bpo-36384: ipaddress module no longer accepts any leading zeros in IPv4 address strings. Leading zeros are ambiguous and interpreted as octal notation by some libraries. For example the legacy function socket.inet_aton() treats leading zeros as octal notation. glibc implementation of modern inet_pton() does not accept any leading zeros. For a while the ipaddress module used to accept ambiguous leading zeros.

  • bpo-43075: Fix Regular Expression Denial of Service (ReDoS) vulnerability in urllib.request.AbstractBasicAuthHandler. The ReDoS-vulnerable regex has quadratic worst-case complexity and it allows cause a denial of service when identifying crafted invalid RFCs. This ReDoS issue is on the client side and needs remote attackers to control the HTTP server.

  • bpo-42800: Audit hooks are now fired for frame.f_code, traceback.tb_frame, and generator code/frame attribute access.

  • bpo-37363: Add audit events to the http.client module.

Core and Builtins

  • bpo-43977: Prevent classes being both a sequence and a mapping when pattern matching.

  • bpo-43977: Use tp_flags on the class object to determine if the subject is a sequence or mapping when pattern matching. Avoids the need to import collections.abc when pattern matching.

  • bpo-43892: Restore proper validation of complex literal value patterns when parsing match blocks.

  • bpo-43933: Set frame.f_lineno to the line number of the ‘with’ kweyword when executing the call to __exit__.

  • bpo-43933: If the current position in a frame has no line number then set the f_lineno attribute to None, instead of -1, to conform to PEP 626. This should not normally be possible, but might occur in some unusual circumstances.

  • bpo-43963: Importing the _signal module in a subinterpreter has no longer side effects.

  • bpo-42739: The internal representation of line number tables is changed to not use sentinels, and an explicit length parameter is added to the out of process API function PyLineTable_InitAddressRange. This makes the handling of line number tables more robust in some circumstances.

  • bpo-43908: Make re types immutable. Patch by Erlend E. Aasland.

  • bpo-43908: Make the array.array type immutable. Patch by Erlend E. Aasland.

  • bpo-43901: Change class and module objects to lazy-create empty annotations dicts on demand. The annotations dicts are stored in the object’s __dict__ for backwards compatibility.

  • bpo-43892: Match patterns now use new dedicated AST nodes (MatchValue, MatchSingleton, MatchSequence, MatchStar, MatchMapping, MatchClass) rather than reusing expression AST nodes. MatchAs and MatchOr are now defined as pattern nodes rather than as expression nodes. Patch by Nick Coghlan.

  • bpo-42725: Usage of await/yield/yield from and named expressions within an annotation is now forbidden when PEP 563 is activated.

  • bpo-43754: When performing structural pattern matching (PEP 634), captured names are now left unbound until the entire pattern has matched successfully.

  • bpo-42737: Annotations for complex targets (everything beside simple names) no longer cause any runtime effects with from __future__ import annotations.

  • bpo-43914: SyntaxError exceptions raised by the interpreter will highlight the full error range of the expression that consistutes the syntax error itself, instead of just where the problem is detected. Patch by Pablo Galindo.

  • bpo-38605: Revert making from __future__ import annotations the default. This follows the Steering Council decision to postpone PEP 563 changes to at least Python 3.11. See the original email for more information regarding the decision: https://mail.python.org/archives/list/python-dev@python.org/thread/CLVXXPQ2T2LQ5MP2Y53VVQFCXYWQJHKZ/. Patch by Pablo Galindo.

  • bpo-43475: Hashes of NaN values now depend on object identity. Formerly, they always hashed to 0 even though NaN values are not equal to one another. Having the same hash for unequal values caused pile-ups in hash tables.

  • bpo-43859: Improve the error message for IndentationError exceptions. Patch by Pablo Galindo

  • bpo-41323: Constant tuple folding in bytecode optimizer now reuses tuple in constant table.

  • bpo-43846: Data stack usage is much reduced for large literal and call expressions.

  • bpo-38530: When printing NameError raised by the interpreter, PyErr_Display() will offer suggestions of similar variable names in the function that the exception was raised from. Patch by Pablo Galindo

  • bpo-43823: Improve syntax errors for invalid dictionary literals. Patch by Pablo Galindo.

  • bpo-43822: Improve syntax errors in the parser for missing commas between expressions. Patch by Pablo Galindo.

  • bpo-43798: ast.alias nodes now include source location metadata attributes e.g. lineno, col_offset.

  • bpo-43797: Improve SyntaxError error messages for invalid comparisons. Patch by Pablo Galindo.

  • bpo-43760: Move the flag for checking whether tracing is enabled to the C stack, from the heap. Should speed up dispatch in the interpreter.

  • bpo-43682: Static methods (@staticmethod) and class methods (@classmethod) now inherit the method attributes (__module__, __name__, __qualname__, __doc__, __annotations__) and have a new __wrapped__ attribute. Patch by Victor Stinner.

  • bpo-43751: Fixed a bug where anext(ait, default) would erroneously return None.

  • bpo-42128: __match_args__ is no longer allowed to be a list.

  • bpo-43683: Add GEN_START opcode. Marks start of generator, including async, or coroutine and handles sending values to a newly created generator or coroutine.

  • bpo-43105: Importlib now resolves relative paths when creating module spec objects from file locations.

  • bpo-43682: Static methods (@staticmethod) are now callable as regular functions. Patch by Victor Stinner.

  • bpo-42609: Prevented crashes in the AST validator and optimizer when compiling some absurdly long expressions like "+0"*1000000. RecursionError is now raised instead.

  • bpo-38530: When printing AttributeError, PyErr_Display() will offer suggestions of similar attribute names in the object that the exception was raised from. Patch by Pablo Galindo

Library

  • bpo-44015: In @dataclass(), raise a TypeError if KW_ONLY is specified more than once.

  • bpo-25478: Added a total() method to collections.Counter() to compute the sum of the counts.

  • bpo-43733: Change netrc.netrc to use UTF-8 encoding before using locale encoding.

  • bpo-43979: Removed an unnecessary list comprehension before looping from urllib.parse.parse_qsl(). Patch by Christoph Zwerschke and Donghee Na.

  • bpo-43993: Update bundled pip to 21.1.1.

  • bpo-43957: [Enum] Deprecate TypeError when non-member is used in a containment check; In 3.12 True or False will be returned instead, and containment will return True if the value is either a member of that enum or one of its members’ value.

  • bpo-42904: For backwards compatibility with previous minor versions of Python, if typing.get_type_hints() receives no namespace dictionary arguments, typing.get_type_hints() will search through the global then local namespaces during evaluation of stringized type annotations (string forward references) inside a class.

  • bpo-43945: [Enum] Deprecate non-standard mixin format() behavior: in 3.12 the enum member, not the member’s value, will be used for format() calls.

  • bpo-41139: Deprecate undocumented cgi.log() API.

  • bpo-43937: Fixed the turtle module working with non-default root window.

  • bpo-43930: Update bundled pip to 21.1 and setuptools to 56.0.0

  • bpo-43907: Fix a bug in the pure-Python pickle implementation when using protocol 5, where bytearray instances that occur several time in the pickled object graph would incorrectly unpickle into repeated copies of the bytearray object.

  • bpo-43926: In importlib.metadata, provide a uniform interface to Description, allow for any field to be encoded with multiline values, remove continuation lines from multiline values, and add a .json property for easy access to the PEP 566 JSON-compatible form. Sync with importlib_metadata 4.0.

  • bpo-43920: OpenSSL 3.0.0: load_verify_locations() now returns a consistent error message when cadata contains no valid certificate.

  • bpo-43607: urllib can now convert Windows paths with \\?\ prefixes into URL paths.

  • bpo-43817: Add inspect.get_annotations(), which safely computes the annotations defined on an object. It works around the quirks of accessing the annotations from various types of objects, and makes very few assumptions about the object passed in. inspect.get_annotations() can also correctly un-stringize stringized annotations.

    inspect.signature(), inspect.from_callable(), and inspect.from_function() now call inspect.get_annotations() to retrieve annotations. This means inspect.signature() and inspect.from_callable() can now un-stringize stringized annotations, too.

  • bpo-43284: platform.win32_ver derives the windows version from sys.getwindowsversion().platform_version which in turn derives the version from kernel32.dll (which can be of a different version than Windows itself). Therefore change the platform.win32_ver to determine the version using the platform module’s _syscmd_ver private function to return an accurate version.

  • bpo-42854: The ssl module now uses SSL_read_ex and SSL_write_ex internally. The functions support reading and writing of data larger than 2 GB. Writing zero-length data no longer fails with a protocol violation error.

  • bpo-42333: Port _ssl extension module to multiphase initialization.

  • bpo-43880: ssl now raises DeprecationWarning for OP_NO_SSL/TLS* options, old TLS versions, old protocols, and other features that have been deprecated since Python 3.6, 3.7, or OpenSSL 1.1.0.

  • bpo-41559: PEP 612 is now implemented purely in Python; builtin types.GenericAlias objects no longer include typing.ParamSpec in __parameters__ (with the exception of collections.abc.Callable‘s GenericAlias). This means previously invalid uses of ParamSpec (such as list[P]) which worked in earlier versions of Python 3.10 alpha, will now raise TypeError during substitution.

  • bpo-43867: The multiprocessing Server class now explicitly catches SystemExit and closes the client connection in this case. It happens when the Server.serve_client() method reaches the end of file (EOF).

  • bpo-40443: Remove unused imports: pyclbr no longer uses copy, and typing no longer uses ast. Patch by Victor Stinner.

  • bpo-43820: Remove an unneeded copy of the namespace passed to dataclasses.make_dataclass().

  • bpo-43787: Add __iter__() method to bz2.BZ2File, gzip.GzipFile, and lzma.LZMAFile. It makes iterating them about 2x faster. Patch by Inada Naoki.

  • bpo-43680: Deprecate io.OpenWrapper and _pyio.OpenWrapper: use io.open and _pyio.open instead. Until Python 3.9, _pyio.open was not a static method and builtins.open was set to OpenWrapper to not become a bound method when set to a class variable. _io.open is a built-in function whereas _pyio.open is a Python function. In Python 3.10, _pyio.open() is now a static method, and builtins.open() is now io.open().

  • bpo-43680: The Python _pyio.open() function becomes a static method to behave as io.open() built-in function: don’t become a bound method when stored as a class variable. It becomes possible since static methods are now callable in Python 3.10. Moreover, _pyio.OpenWrapper() becomes a simple alias to _pyio.open(). Patch by Victor Stinner.

  • bpo-41515: Fix KeyError raised in typing.get_type_hints() due to synthetic modules that don’t appear in sys.modules.

  • bpo-43776: When subprocess.Popen args are provided as a string or as pathlib.Path, the Popen instance repr now shows the right thing.

  • bpo-42248: [Enum] ensure exceptions raised in _missing__ are released

  • bpo-43744: fix issue with enum member name matching the start of a private variable name

  • bpo-43772: Fixed the return value of TypeVar.__ror__. Patch by Jelle Zijlstra.

  • bpo-43764: Add match_args parameter to @dataclass decorator to allow suppression of __match_args__ generation.

  • bpo-43799: OpenSSL 3.0.0: define OPENSSL_API_COMPAT 1.1.1 to suppress deprecation warnings. Python requires OpenSSL 1.1.1 APIs.

  • bpo-43478: Mocks can no longer be used as the specs for other Mocks. As a result, an already-mocked object cannot have an attribute mocked using autospec=True or be the subject of a create_autospec(...) call. This can uncover bugs in tests since these Mock-derived Mocks will always pass certain tests (e.g. isinstance()) and builtin assert functions (e.g. assert_called_once_with) will unconditionally pass.

  • bpo-43794: Add ssl.OP_IGNORE_UNEXPECTED_EOF constants (OpenSSL 3.0.0)

  • bpo-43785: Improve bz2.BZ2File performance by removing the RLock from BZ2File. This makes BZ2File thread unsafe in the face of multiple simultaneous readers or writers, just like its equivalent classes in gzip and lzma have always been. Patch by Inada Naoki.

  • bpo-43789: OpenSSL 3.0.0: Don’t call the password callback function a second time when first call has signaled an error condition.

  • bpo-43788: The header files for ssl error codes are now OpenSSL version-specific. Exceptions will now show correct reason and library codes. The make_ssl_data.py script has been rewritten to use OpenSSL’s text file with error codes.

  • bpo-43766: Implement PEP 647 in the typing module by adding TypeGuard.

  • bpo-25264: os.path.realpath() now accepts a strict keyword-only argument. When set to True, OSError is raised if a path doesn’t exist or a symlink loop is encountered.

  • bpo-43780: In importlib.metadata, incorporate changes from importlib_metadata 3.10: Add mtime-based caching during distribution discovery. Flagged use of dict result from entry_points() as deprecated.

  • gh-47383: The P.args and P.kwargs attributes of typing.ParamSpec are now instances of the new classes typing.ParamSpecArgs and typing.ParamSpecKwargs, which enables a more useful repr(). Patch by Jelle Zijlstra.

  • bpo-43731: Add an encoding parameter logging.fileConfig().

  • bpo-43712: Add encoding and errors parameters to fileinput.input() and fileinput.FileInput.

  • bpo-38659: A simple_enum decorator is added to the enum module to convert a normal class into an Enum. test_simple_enum added to test simple enums against a corresponding normal Enum. Standard library modules updated to use simple_enum.

  • bpo-43764: Fix an issue where __match_args__ generation could fail for some dataclasses.

  • bpo-43752: Fix sqlite3 regression for zero-sized blobs with converters, where b"" was returned instead of None. The regression was introduced by PR 24723. Patch by Erlend E. Aasland.

  • bpo-43655: tkinter dialog windows are now recognized as dialogs by window managers on macOS and X Window.

  • bpo-43723: The following threading methods are now deprecated and should be replaced:

    Patch by Jelle Zijlstra.

  • bpo-2135: Deprecate find_module() and find_loader() implementations in importlib and zipimport.

  • bpo-43534: turtle.textinput() and turtle.numinput() create now a transient window working on behalf of the canvas window.

  • bpo-43532: Add the ability to specify keyword-only fields to dataclasses. These fields will become keyword-only arguments to the generated __init__.

  • bpo-43522: Fix problem with hostname_checks_common_name. OpenSSL does not copy hostflags from struct SSL_CTX to struct SSL.

  • bpo-8978: Improve error message for tarfile.open() when lzma / bz2 are unavailable. Patch by Anthony Sottile.

  • bpo-42967: Allow bytes separator argument in urllib.parse.parse_qs and urllib.parse.parse_qsl when parsing str query strings. Previously, this raised a TypeError.

  • bpo-43296: Improve sqlite3 error handling: sqlite3_value_blob() errors that set SQLITE_NOMEM now raise MemoryError. Patch by Erlend E. Aasland.

  • bpo-43312: New functions sysconfig.get_preferred_scheme() and sysconfig.get_default_scheme() are added to query a platform for its preferred “user”, “home”, and “prefix” (default) scheme names.

  • bpo-43265: Improve sqlite3.Connection.backup() error handling. The error message for non-existent target database names is now unknown database <database name> instead of SQL logic error. Patch by Erlend E. Aasland.

  • bpo-41282: Install schemes in distutils.command.install are now loaded from sysconfig.

  • bpo-41282: distutils.sysconfig has been merged to sysconfig.

  • bpo-43176: Fixed processing of a dataclass that inherits from a frozen dataclass with no fields. It is now correctly detected as an error.

  • bpo-43080: pprint now has support for dataclasses.dataclass. Patch by Lewis Gaul.

  • bpo-39950: Add pathlib.Path.hardlink_to() method that supersedes link_to(). The new method has the same argument order as symlink_to().

  • bpo-42904: typing.get_type_hints() now checks the local namespace of a class when evaluating PEP 563 annotations inside said class.

  • bpo-42269: Add slots parameter to dataclasses.dataclass decorator to automatically generate __slots__ for class. Patch provided by Yurii Karabas.

  • bpo-39529: Deprecated use of asyncio.get_event_loop() without running event loop. Emit deprecation warning for asyncio functions which implicitly create a Future or Task objects if there is no running event loop and no explicit loop argument is passed: ensure_future(), wrap_future(), gather(), shield(), as_completed() and constructors of Future, Task, StreamReader, StreamReaderProtocol.

  • bpo-18369: Certificate and PrivateKey classes were added to the ssl module. Certificates and keys can now be loaded from memory buffer, too.

  • bpo-41486: Use a new output buffer management code for bz2 / lzma / zlib modules, and add .readall() function to _compression.DecompressReader class. These bring some performance improvements. Patch by Ma Lin.

  • bpo-31870: The ssl.get_server_certificate() function now has a timeout parameter.

  • bpo-41735: Fix thread locks in zlib module may go wrong in rare case. Patch by Ma Lin.

  • bpo-36470: Fix dataclasses with InitVars and replace(). Patch by Claudiu Popa.

  • bpo-40849: Expose X509_V_FLAG_PARTIAL_CHAIN ssl flag

  • bpo-35114: ssl.RAND_status() now returns a boolean value (as documented) instead of 1 or 0.

  • bpo-39906: pathlib.Path.stat() and chmod() now accept a follow_symlinks keyword-only argument for consistency with corresponding functions in the os module.

  • bpo-39899: os.path.expanduser() now refuses to guess Windows home directories if the basename of current user’s home directory does not match their username.

    pathlib.Path.expanduser() and home() now consistently raise RuntimeError exception when a home directory cannot be resolved. Previously a KeyError exception could be raised on Windows when the "USERNAME" environment variable was unset.

  • bpo-36076: Added SNI support to ssl.get_server_certificate().

  • bpo-38490: Covariance, Pearson’s correlation, and simple linear regression functionality was added to statistics module. Patch by Tymoteusz Wołodźko.

  • bpo-33731: Provide a locale.localize() function, which converts a normalized number string into a locale format.

  • bpo-32745: Fix a regression in the handling of ctypes’ ctypes.c_wchar_p type: embedded null characters would cause a ValueError to be raised. Patch by Zackery Spytz.

Documentation

  • bpo-43987: Add “Annotations Best Practices” document as a new HOWTO.

  • bpo-43977: Document the new Py_TPFLAGS_MAPPING and Py_TPFLAGS_SEQUENCE type flags.

  • bpo-43959: The documentation on the PyContextVar C-API was clarified.

  • bpo-43938: Update dataclasses documentation to express that FrozenInstanceError is derived from AttributeError.

  • bpo-43778: Fix the Sphinx glossary_search extension: create the _static/ sub-directory if it doesn’t exist.

  • bpo-43755: Update documentation to reflect that unparenthesized lambda expressions can no longer be the expression part in an if clause in comprehensions and generator expressions since Python 3.9.

  • bpo-43739: Fixing the example code in Doc/extending/extending.rst to declare and initialize the pmodule variable to be of the right type.

Tests

  • bpo-43961: Fix test_logging.test_namer_rotator_inheritance() on Windows: use os.replace() rather than os.rename(). Patch by Victor Stinner.

  • bpo-43842: Fix a race condition in the SMTP test of test_logging. Don’t close a file descriptor (socket) from a different thread while asyncore.loop() is polling the file descriptor. Patch by Victor Stinner.

  • bpo-43843: test.libregrtest now marks a test as ENV_CHANGED (altered the execution environment) if a thread raises an exception but does not catch it. It sets a hook on threading.excepthook(). Use --fail-env-changed option to mark the test as failed. Patch by Victor Stinner.

  • bpo-43811: Tests multiple OpenSSL versions on GitHub Actions. Use ccache to speed up testing.

  • bpo-43791: OpenSSL 3.0.0: Disable testing of legacy protocols TLS 1.0 and 1.1. Tests are failing with TLSV1_ALERT_INTERNAL_ERROR.

Build

  • bpo-43567: Improved generated code refresh (AST/tokens/opcodes/keywords) on Windows.

  • bpo-43669: Implement PEP 644. Python now requires OpenSSL 1.1.1 or newer.

Windows

  • bpo-35306: Adds additional arguments to os.startfile() function.

  • bpo-43538: Avoid raising errors from pathlib.Path.exists() when passed an invalid filename.

  • bpo-38822: Fixed os.stat() failing on inaccessible directories with a trailing slash, rather than falling back to the parent directory’s metadata. This implicitly affected os.path.exists() and os.path.isdir().

  • bpo-26227: Fixed decoding of host names in socket.gethostbyaddr() and socket.gethostbyname_ex().

  • bpo-40432: Updated pegen regeneration script on Windows to find and use Python 3.8 or higher. Prior to this, pegen regeneration already required 3.8 or higher, but the script may have used lower versions of Python.

  • bpo-43745: Actually updates Windows release to OpenSSL 1.1.1k. Earlier releases were mislabelled and actually included 1.1.1i again.

  • bpo-43652: Update Tcl and Tk to 8.6.11 in Windows installer.

  • bpo-43492: Upgrade Windows installer to use SQLite 3.35.5.

  • bpo-30555: Fix WindowsConsoleIO errors in the presence of fd redirection. Patch by Segev Finer.

macOS

  • bpo-42119: Fix check for macOS SDK paths when building Python. Narrow search to match contents of SDKs, namely only files in /System/Library, /System/IOSSupport, and /usr other than /usr/local. Previously, anything under /System was assumed to be in an SDK which causes problems with the new file system layout in 10.15+ where user file systems may appear to be mounted under /System. Paths in /Library were also incorrectly treated as SDK locations.

  • bpo-43568: Drop support for MACOSX_DEPLOYMENT_TARGET < 10.3

  • bpo-44009: Provide “python3.x-intel64” executable to allow reliably forcing macOS universal2 framework builds to run under Rosetta 2 Intel-64 emulation on Apple Silicon Macs. This can be useful for testing or when universal2 wheels are not yet available.

  • bpo-43851: Build SQLite with SQLITE_OMIT_AUTOINIT on macOS. Patch by Erlend E. Aasland.

  • bpo-43492: Update macOS installer to use SQLite 3.35.4.

  • bpo-42235: Mac/BuildScript/build-installer.py will now use “–enable-optimizations” and --with-lto when building on macOS 10.15 or later.

IDLE

  • bpo-37903: Add mouse actions to the shell sidebar. Left click and optional drag selects one or more lines, as with the editor line number sidebar. Right click after selecting raises a context menu with ‘copy with prompts’. This zips together prompts from the sidebar with lines from the selected text.

  • bpo-43981: Fix reference leak in test_sidebar and test_squeezer. Patches by Terry Jan Reedy and Pablo Galindo

  • bpo-37892: Indent IDLE Shell input with spaces instead of tabs

  • bpo-43655: IDLE dialog windows are now recognized as dialogs by window managers on macOS and X Window.

  • bpo-37903: IDLE’s shell now shows prompts in a separate side-bar.

C API

  • bpo-43916: Add a new Py_TPFLAGS_DISALLOW_INSTANTIATION type flag to disallow creating type instances. Patch by Victor Stinner.

  • bpo-43774: Remove the now unused PYMALLOC_DEBUG macro. Debug hooks on memory allocators are now installed by default if Python is built in debug mode (if Py_DEBUG macro is defined). Moreover, they can now be used on Python build in release mode (ex: using PYTHONMALLOC=debug environment variable).

  • bpo-43962: _PyInterpreterState_IDIncref() now calls _PyInterpreterState_IDInitref() and always increments id_refcount. Previously, calling _xxsubinterpreters.get_current() could create an id_refcount inconsistency when a _xxsubinterpreters.InterpreterID object was deallocated. Patch by Victor Stinner.

  • bpo-28254: Add new C-API functions to control the state of the garbage collector: PyGC_Enable(), PyGC_Disable(), PyGC_IsEnabled(), corresponding to the functions in the gc module.

  • bpo-43908: Introduce Py_TPFLAGS_IMMUTABLETYPE flag for immutable type objects, and modify PyType_Ready() to set it for static types. Patch by Erlend E. Aasland.

  • bpo-43795: PyMem_Calloc() is now available in the limited C API (Py_LIMITED_API).

  • bpo-43868: PyOS_ReadlineFunctionPointer() is no longer exported by limited C API headers and by python3.dll on Windows. Like any function that takes FILE*, it is not part of the stable ABI.

  • bpo-43795: Stable ABI and limited API definitions are generated from a central manifest (PEP 652).

  • bpo-43753: Add the Py_Is(x, y) function to test if the x object is the y object, the same as x is y in Python. Add also the Py_IsNone(), Py_IsTrue(), Py_IsFalse() functions to test if an object is, respectively, the None singleton, the True singleton or the False singleton. Patch by Victor Stinner.

Python 3.10.0 alpha 7

Release date: 2021-04-05

Security

  • bpo-42988: CVE-2021-3426: Remove the getfile feature of the pydoc module which could be abused to read arbitrary files on the disk (directory traversal vulnerability). Moreover, even source code of Python modules can contain sensitive data like passwords. Vulnerability reported by David Schwörer.

  • bpo-43285: ftplib no longer trusts the IP address value returned from the server in response to the PASV command by default. This prevents a malicious FTP server from using the response to probe IPv4 address and port combinations on the client network.

    Code that requires the former vulnerable behavior may set a trust_server_pasv_ipv4_address attribute on their ftplib.FTP instances to True to re-enable it.

  • bpo-43439: Add audit hooks for gc.get_objects(), gc.get_referrers() and gc.get_referents(). Patch by Pablo Galindo.

Core and Builtins

  • bpo-27129: Update CPython bytecode magic number.

  • bpo-43672: Raise ImportWarning when calling find_loader().

  • bpo-43660: Fix crash that happens when replacing sys.stderr with a callable that can remove the object while an exception is being printed. Patch by Pablo Galindo.

  • bpo-27129: The bytecode interpreter uses instruction, rather byte, offsets internally. This reduces the number of EXTENDED_ARG instructions needed and streamlines instruction dispatch a bit.

  • bpo-40645: Fix reference leak in the _hashopenssl extension. Patch by Pablo Galindo.

  • bpo-42134: Calls to find_module() by the import system now raise ImportWarning.

  • bpo-41064: Improve the syntax error for invalid usage of double starred elements (‘**’) in f-strings. Patch by Pablo Galindo.

  • bpo-43575: Speed up calls to map() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-42137: The import system now prefers using __spec__ for ModuleType.__repr__ over module_repr().

  • bpo-43452: Added micro-optimizations to _PyType_Lookup() to improve cache lookup performance in the common case of cache hits.

  • bpo-43555: Report the column offset for SyntaxError for invalid line continuation characters. Patch by Pablo Galindo.

  • bpo-43517: Fix misdetection of circular imports when using from pkg.mod import attr, which caused false positives in non-trivial multi-threaded code.

  • bpo-43497: Emit SyntaxWarnings for assertions with tuple constants, this is a regression introduced in python3.7

  • bpo-39316: Tracing now has correct line numbers for attribute accesses when the attribute is on a different line from the object. Improves debugging and profiling for multi-line method chains.

  • bpo-35883: Python no longer fails at startup with a fatal error if a command line argument contains an invalid Unicode character. The Py_DecodeLocale() function now escapes byte sequences which would be decoded as Unicode characters outside the [U+0000; U+10ffff] range.

  • bpo-43410: Fix a bug that was causing the parser to crash when emitting syntax errors when reading input from stdin. Patch by Pablo Galindo

  • bpo-43406: Fix a possible race condition where PyErr_CheckSignals tries to execute a non-Python signal handler.

  • bpo-42128: Add __match_args__ to struct sequence objects. Patch by Pablo Galindo.

  • bpo-43390: CPython now sets the SA_ONSTACK flag in PyOS_setsig for the VM’s default signal handlers. This is friendlier to other in-process code that an extension module or embedding use could pull in (such as Golang’s cgo) where tiny thread stacks are the norm and sigaltstack() has been used to provide for signal handlers. This is a no-op change for the vast majority of processes that don’t use sigaltstack.

  • bpo-43287: Speed up calls to filter() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-37448: Add a radix tree based memory map to track in-use obmalloc arenas. Use to replace the old implementation of address_in_range(). The radix tree approach makes it easy to increase pool sizes beyond the OS page size. Boosting the pool and arena size allows obmalloc to handle a significantly higher percentage of requests from its ultra-fast paths.

    It also has the advantage of eliminating the memory unsanitary behavior of the previous address_in_range(). The old address_in_range() was marked with the annotations _Py_NO_SANITIZE_ADDRESS, _Py_NO_SANITIZE_THREAD, and _Py_NO_SANITIZE_MEMORY. Those annotations are no longer needed.

    To disable the radix tree map, set a preprocessor flag as follows: -DWITH_PYMALLOC_RADIX_TREE=0.

    Co-authored-by: Tim Peters <tim.peters@gmail.com>

  • bpo-29988: Only handle asynchronous exceptions and requests to drop the GIL when returning from a call or on the back edges of loops. Makes sure that __exit__() is always called in with statements, even for interrupts.

Library

  • bpo-43720: Document various stdlib deprecations in imp, pkgutil, and importlib.util for removal in Python 3.12.

  • bpo-43433: xmlrpc.client.ServerProxy no longer ignores query and fragment in the URL of the server.

  • bpo-31956: The index() method of array.array now has optional start and stop parameters.

  • bpo-40066: Enum: adjust repr() to show only enum and member name (not value, nor angle brackets) and str() to show only member name. Update and improve documentation to match.

  • bpo-42136: Deprecate all module_repr() methods found in importlib as their use is being phased out by Python 3.12.

  • bpo-35930: Raising an exception raised in a “future” instance will create reference cycles.

  • bpo-41369: Finish updating the vendored libmpdec to version 2.5.1. Patch by Stefan Krah.

  • bpo-43422: Revert the _decimal C API which was added in bpo-41324.

  • bpo-43577: Fix deadlock when using ssl.SSLContext debug callback with ssl.SSLContext.sni_callback().

  • bpo-43571: It’s now possible to create MPTCP sockets with IPPROTO_MPTCP

  • bpo-43542: image/heic and image/heif were added to mimetypes.

  • bpo-40645: The hmac module now uses OpenSSL’s HMAC implementation when digestmod argument is a hash name or builtin hash function.

  • bpo-43510: Implement PEP 597: Add EncodingWarning warning, -X warn_default_encoding option, PYTHONWARNDEFAULTENCODING environment variable and encoding="locale" argument value.

  • bpo-43521: ast.unparse can now render NaNs and empty sets.

  • bpo-42914: pprint.pprint() gains a new boolean underscore_numbers optional argument to emit integers with thousands separated by an underscore character for improved readability (for example 1_000_000 instead of 1000000).

  • bpo-41361: rotate() calls are now slightly faster due to faster argument parsing.

  • bpo-43423: subprocess.communicate() no longer raises an IndexError when there is an empty stdout or stderr IO buffer during a timeout on Windows.

  • bpo-27820: Fixed long-standing bug of smtplib.SMTP where doing AUTH LOGIN with initial_response_ok=False will fail.

    The cause is that SMTP.auth_login _always_ returns a password if provided with a challenge string, thus non-compliant with the standard for AUTH LOGIN.

    Also fixes bug with the test for smtpd.

  • bpo-43445: Add frozen modules to sys.stdlib_module_names. For example, add "_frozen_importlib" and "_frozen_importlib_external" names.

  • bpo-43245: Add keyword arguments support to ChainMap.new_child().

  • bpo-29982: Add optional parameter ignore_cleanup_errors to tempfile.TemporaryDirectory() and allow multiple cleanup() attempts. Contributed by C.A.M. Gerlach.

  • bpo-43428: Include changes from importlib_metadata 3.7:

    Performance enhancements to distribution discovery.

    entry_points only returns unique distributions.

    Introduces new EntryPoints object for containing a set of entry points with convenience methods for selecting entry points by group or name. entry_points now returns this object if selection parameters are supplied but continues to return a dict object for compatibility. Users are encouraged to rely on the selection interface. The dict object result is likely to be deprecated in the future.

    Added packages_distributions function to return a mapping of packages to the distributions that provide them.

  • bpo-43332: Improves the networking efficiency of http.client when using a proxy via set_tunnel(). Fewer small send calls are made during connection setup.

  • bpo-43420: Improve performance of fractions.Fraction arithmetics for large components. Contributed by Sergey B. Kirpichev.

  • bpo-43356: Allow passing a signal number to _thread.interrupt_main().

  • bpo-43399: Fix ElementTree.extend not working on iterators when using the Python implementation

  • bpo-43369: Improve sqlite3 error handling: If sqlite3_column_text() and sqlite3_column_blob() set SQLITE_NOMEM, MemoryError is now raised. Patch by Erlend E. Aasland.

  • bpo-43368: Fix a regression introduced in PR 24562, where an empty bytestring was fetched as None instead of b'' in sqlite3. Patch by Mariusz Felisiak.

  • bpo-41282: Fixed stacklevel of DeprecationWarning emitted from import distutils.

  • bpo-42129: importlib.resources now honors namespace packages, merging resources from each location in the namespace as introduced in importlib_resources 3.2 and including incidental changes through 5.0.3.

  • bpo-43295: datetime.datetime.strptime() now raises ValueError instead of IndexError when matching 'z' with the %z format specifier.

  • bpo-43125: Return empty string if base64mime.body_encode receive empty bytes

  • bpo-43084: curses.window.enclose() returns now True or False (as was documented) instead of 1 or 0.

  • bpo-42994: Add MIME types for opus, AAC, 3gpp and 3gpp2

  • bpo-14678: Add an invalidate_caches() method to the zipimport.zipimporter class to support importlib.invalidate_caches(). Patch by Desmond Cheong.

  • bpo-42782: Fail fast in shutil.move() to avoid creating destination directories on failure.

  • bpo-40066: Enum’s repr() and str() have changed: repr() is now EnumClass.MemberName and str() is MemberName. Additionally, stdlib Enum’s whose contents are available as module attributes, such as RegexFlag.IGNORECASE, have their repr() as module.name, e.g. re.IGNORECASE.

  • bpo-26053: Fixed bug where the pdb interactive run command echoed the args from the shell command line, even if those have been overridden at the pdb prompt.

  • bpo-24160: Fixed bug where breakpoints did not persist across multiple debugger sessions in pdb’s interactive mode.

  • bpo-40701: When the tempfile.tempdir global variable is set to a value of type bytes, it is now handled consistently. Previously exceptions could be raised from some tempfile APIs when the directory did not already exist in this situation. Also ensures that the tempfile.gettempdir() and tempfile.gettempdirb() functions always return str and bytes respectively.

  • bpo-39342: Expose X509_V_FLAG_ALLOW_PROXY_CERTS as VERIFY_ALLOW_PROXY_CERTS to allow proxy certificate validation as explained in https://www.openssl.org/docs/man1.1.1/man7/proxy-certificates.html.

  • bpo-31861: Add builtins.aiter and builtins.anext. Patch by Joshua Bronson (@jab), Daniel Pope (@lordmauve), and Justin Wang (@justin39).

Documentation

Tests

  • bpo-37945: Fix test_getsetlocale_issue1813() of test_locale: skip the test if setlocale() fails. Patch by Victor Stinner.

  • bpo-41561: Add workaround for Ubuntu’s custom OpenSSL security level policy.

Build

  • bpo-43179: Introduce and correctly use ALIGNOF_X in place of SIZEOF_X for alignment-related code in optimized string routines. Patch by Jessica Clarke.

  • bpo-43631: Update macOS, Windows, and CI to OpenSSL 1.1.1k.

  • bpo-43617: Improve configure.ac: Check for presence of autoconf-archive package and remove our copies of M4 macros.

  • bpo-43466: The configure script now supports --with-openssl-rpath option.

  • bpo-43372: Use _freeze_importlib to generate code for the __hello__ module. This approach ensures the code matches the interpreter version. Previously, PYTHON_FOR_REGEN was used to generate the code, which might be wrong. The marshal format for code objects has changed with bpo-42246, commit 877df851. Update the code and the expected code sizes in ctypes test_frozentable.

Windows

  • bpo-43440: Build sqlite3 with the R*Tree module enabled. Patch by Erlend E. Aasland.

IDLE

  • bpo-42225: Document that IDLE can fail on Unix either from misconfigured IP masquerade rules or failure displaying complex colored (non-ascii) characters.

C API

  • bpo-43688: The limited C API is now supported if Python is built in debug mode (if the Py_DEBUG macro is defined). In the limited C API, the Py_INCREF() and Py_DECREF() functions are now implemented as opaque function calls, rather than accessing directly the PyObject.ob_refcnt member, if Python is built in debug mode and the Py_LIMITED_API macro targets Python 3.10 or newer. It became possible to support the limited C API in debug mode because the PyObject structure is the same in release and debug mode since Python 3.8 (see bpo-36465).

    The limited C API is still not supported in the --with-trace-refs special build (Py_TRACE_REFS macro).

    Patch by Victor Stinner.

  • bpo-43244: Remove the pyarena.h header file with functions:

    • PyArena_New()

    • PyArena_Free()

    • PyArena_Malloc()

    • PyArena_AddPyObject()

    These functions were undocumented, excluded from the limited C API, and were only used internally by the compiler. Patch by Victor Stinner.

  • bpo-43244: Remove the compiler and parser functions using struct _mod type, because the public AST C API was removed:

    • PyAST_Compile()

    • PyAST_CompileEx()

    • PyAST_CompileObject()

    • PyFuture_FromAST()

    • PyFuture_FromASTObject()

    • PyParser_ASTFromFile()

    • PyParser_ASTFromFileObject()

    • PyParser_ASTFromFilename()

    • PyParser_ASTFromString()

    • PyParser_ASTFromStringObject()

    These functions were undocumented and excluded from the limited C API. Patch by Victor Stinner.

  • bpo-43244: Remove ast.h, asdl.h, and Python-ast.h header files. These functions were undocumented and excluded from the limited C API. Most names defined by these header files were not prefixed by Py and so could create names conflicts. For example, Python-ast.h defined a Yield macro which was conflict with the Yield name used by the Windows <winbase.h> header. Use the Python ast module instead. Patch by Victor Stinner.

  • bpo-43541: Fix a PyEval_EvalCodeEx() regression: fix reference counting on builtins. Patch by Victor Stinner.

  • bpo-43244: Remove the symtable.h header file and the undocumented functions:

    • PyST_GetScope()

    • PySymtable_Build()

    • PySymtable_BuildObject()

    • PySymtable_Free()

    • Py_SymtableString()

    • Py_SymtableStringObject()

    The Py_SymtableString() function was part the stable ABI by mistake but it could not be used, because the symtable.h header file was excluded from the limited C API.

    The Python symtable module remains available and is unchanged.

    Patch by Victor Stinner.

  • bpo-43244: Remove the PyAST_Validate() function. It is no longer possible to build a AST object (mod_ty type) with the public C API. The function was already excluded from the limited C API (PEP 384). Patch by Victor Stinner.

Python 3.10.0 alpha 6

Release date: 2021-03-01

Security

  • bpo-42967: Fix web cache poisoning vulnerability by defaulting the query args separator to &, and allowing the user to choose a custom separator.

Core and Builtins

  • bpo-43321: Fix SystemError raised when PyArg_Parse*() is used with # but without PY_SSIZE_T_CLEAN defined.

  • bpo-36346: PyArg_Parse*() functions now emits DeprecationWarning when u or Z format is used. See PEP 623 for detail.

  • bpo-43277: Add a new PySet_CheckExact() function to the C-API to check if an object is an instance of set but not an instance of a subtype. Patch by Pablo Galindo.

  • bpo-42990: The types.FunctionType constructor now inherits the current builtins if the globals dictionary has no "__builtins__" key, rather than using {"None": None} as builtins: same behavior as eval() and exec() functions. Defining a function with def function(...): ... in Python is not affected, globals cannot be overridden with this syntax: it also inherits the current builtins. Patch by Victor Stinner.

  • bpo-42990: Functions have a new __builtins__ attribute which is used to look for builtin symbols when a function is executed, instead of looking into __globals__['__builtins__']. Patch by Mark Shannon and Victor Stinner.

  • bpo-43149: Improve the error message in the parser for exception groups without parentheses. Patch by Pablo Galindo.

  • bpo-43121: Fixed an incorrect SyntaxError message for missing comma in literals. Patch by Pablo Galindo.

  • bpo-42819: readline: Explicitly disable bracketed paste in the interactive interpreter, even if it’s set in the inputrc, is enabled by default (eg GNU Readline 8.1), or a user calls readline.read_init_file(). The Python REPL has not implemented bracketed paste support. Also, bracketed mode writes the "\x1b[?2004h" escape sequence into stdout which causes test failures in applications that don’t support it. It can still be explicitly enabled by calling readline.parse_and_bind("set enable-bracketed-paste on"). Patch by Dustin Rodrigues.

  • bpo-42808: Simple calls to type(object) are now faster due to the vectorcall calling convention. Patch by Dennis Sweeney.

  • bpo-42217: Make the compiler merges same co_code and co_linetable objects in a module like already did for co_consts.

  • bpo-41972: Substring search functions such as str1 in str2 and str2.find(str1) now sometimes use the “Two-Way” string comparison algorithm to avoid quadratic behavior on long strings.

  • bpo-42128: Implement PEP 634 (structural pattern matching). Patch by Brandt Bucher.

  • bpo-40692: In the concurrent.futures.ProcessPoolExecutor, validate that multiprocess.synchronize() is available on a given platform and rely on that check in the concurrent.futures test suite so we can run tests that are unrelated to ProcessPoolExecutor on those platforms.

  • bpo-38302: If object.__ipow__() returns NotImplemented, the operator will correctly fall back to object.__pow__() and object.__rpow__() as expected.

Library

  • bpo-43316: The python -m gzip command line application now properly fails when detecting an unsupported extension. It exits with a non-zero exit code and prints an error message to stderr.

  • bpo-43317: Set the chunk size for the gzip module main function to io.DEFAULT_BUFFER_SIZE. This is slightly faster than the 1024 bytes constant that was used previously.

  • bpo-43146: Handle None in single-arg versions of print_exception() and format_exception().

  • bpo-43260: Fix TextIOWrapper can not flush internal buffer forever after very large text is written.

  • bpo-43258: Prevent needless allocation of sqlite3 aggregate function context when no rows match an aggregate query. Patch by Erlend E. Aasland.

  • bpo-43251: Improve sqlite3 error handling: sqlite3_column_name() failures now result in MemoryError. Patch by Erlend E. Aasland.

  • bpo-40956: Fix segfault in sqlite3.Connection.backup() if no argument was provided. The regression was introduced by PR 23838. Patch by Erlend E. Aasland.

  • bpo-43172: The readline module now passes its tests when built directly against libedit. Existing irreconcilable API differences remain in readline.get_begidx() and readline.get_endidx() behavior based on libreadline vs libedit use.

  • bpo-43163: Fix a bug in codeop that was causing it to not ask for more input when multi-line snippets have unclosed parentheses. Patch by Pablo Galindo

  • bpo-43162: deprecate unsupported ability to access enum members as attributes of other enum members

  • bpo-43146: Fix recent regression in None argument handling in traceback module functions.

  • bpo-43102: The namedtuple __new__ method had its __builtins__ set to None instead of an actual dictionary. This created problems for introspection tools.

  • bpo-43106: Added O_EVTONLY, O_FSYNC, O_SYMLINK and O_NOFOLLOW_ANY for macOS. Patch by Donghee Na.

  • bpo-42960: Adds resource.RLIMIT_KQUEUES constant from FreeBSD to the resource module.

  • bpo-42151: Make the pure Python implementation of xml.etree.ElementTree behave the same as the C implementation (_elementree) regarding default attribute values (by not setting specified_attributes=1).

  • bpo-29753: In ctypes, now packed bitfields are calculated properly and the first item of packed bitfields is now shrank correctly.

Documentation

  • bpo-27646: Clarify that ‘yield from <expr>’ works with any iterable, not just iterators.

  • bpo-36346: Update some deprecated unicode APIs which are documented as “will be removed in 4.0” to “3.12”. See PEP 623 for detail.

Tests

  • bpo-43288: Fix test_importlib to correctly skip Unicode file tests if the filesystem does not support them.

Build

  • bpo-43174: Windows build now uses /utf-8 compiler option.

  • bpo-43103: Add a new configure --without-static-libpython option to not build the libpythonMAJOR.MINOR.a static library and not install the python.o object file.

  • bpo-13501: The configure script can now use libedit instead of readline with the command line option --with-readline=editline.

  • bpo-42603: Make configure script use pkg-config to detect the location of Tcl/Tk headers and libraries, used to build tkinter.

    On macOS, a Tcl/Tk configuration provided by pkg-config will be preferred over Tcl/Tk frameworks installed in /{System/,}Library/Frameworks. If both exist and the latter is preferred, the appropriate --with-tcltk-* configuration options need to be explicitly set.

  • bpo-39448: Add the “regen-frozen” makefile target that regenerates the code for the frozen __hello__ module.

Windows

macOS

  • bpo-41837: Update macOS installer build to use OpenSSL 1.1.1j.

IDLE

  • bpo-43283: Document why printing to IDLE’s Shell is often slower than printing to a system terminal and that it can be made faster by pre-formatting a single string before printing.

C API

  • bpo-43278: Always put compiler and system information on the first line of the REPL welcome message.

  • bpo-43270: Remove the private _PyErr_OCCURRED() macro: use the public PyErr_Occurred() function instead.

  • bpo-35134: Move odictobject.h, parser_interface.h, picklebufobject.h, pydebug.h, and pyfpe.h into the cpython/ directory. They must not be included directly, as they are already included by Python.h: Include Files.

  • bpo-35134: Move pyarena.h, pyctype.h, and pytime.h into the cpython/ directory. They must not be included directly, as they are already included by Python.h: Include Files.

  • bpo-40170: PyExceptionClass_Name() is now always declared as a function, in order to hide implementation details. The macro accessed PyTypeObject.tp_name directly. Patch by Erlend E. Aasland.

  • bpo-43239: The PyCFunction_New() function is now exported in the ABI when compiled with -fvisibility=hidden.

  • bpo-40170: PyIter_Check() is now always declared as a function, in order to hide implementation details. The macro accessed PyTypeObject.tp_iternext directly. Patch by Erlend E. Aasland.

  • bpo-40170: Convert PyDescr_IsData() macro to a function to hide implementation details: The macro accessed PyTypeObject.tp_descr_set directly. Patch by Erlend E. Aasland.

  • bpo-43181: Convert PyObject_TypeCheck() macro to a static inline function. Patch by Erlend E. Aasland.

Python 3.10.0 alpha 5

Release date: 2021-02-02

Security

Core and Builtins

  • bpo-42990: Refactor the PyEval_ family of functions.

    • An new function _PyEval_Vector is added to simplify calls to Python from C.

    • _PyEval_EvalCodeWithName is removed

    • PyEval_EvalCodeEx is retained as part of the API, but is not used internally

  • bpo-38631: Replace Py_FatalError() calls in the compiler with regular SystemError exceptions. Patch by Victor Stinner.

  • bpo-42997: Improve error message for missing “:” before blocks. Patch by Pablo Galindo.

  • bpo-43017: Improve error message in the parser when using un-parenthesised tuples in comprehensions. Patch by Pablo Galindo.

  • bpo-42986: Fix parser crash when reporting syntax errors in f-string with newlines. Patch by Pablo Galindo.

  • bpo-40176: Syntax errors for unterminated string literals now point to the start of the string instead of reporting EOF/EOL.

  • bpo-42927: The inline cache for LOAD_ATTR now also optimizes access to attributes defined by __slots__. This makes reading such attribute up to 30% faster.

  • bpo-42864: Improve error messages in the parser when parentheses are not closed. Patch by Pablo Galindo.

  • bpo-42924: Fix bytearray repetition incorrectly copying data from the start of the buffer, even if the data is offset within the buffer (e.g. after reassigning a slice at the start of the bytearray to a shorter byte string).

  • bpo-42882: Fix the _PyUnicode_FromId() function (_Py_IDENTIFIER(var) API) when Py_Initialize() / Py_Finalize() is called multiple times: preserve _PyRuntime.unicode_ids.next_index value.

  • bpo-42827: Fix a crash when working out the error line of a SyntaxError in some multi-line expressions.

  • bpo-42823: frame.f_lineno is correct even if frame.f_trace is set to True

  • bpo-37324: Remove deprecated aliases to Collections Abstract Base Classes from the collections module.

  • bpo-41994: Fixed possible leak in import when sys.modules is not a dict.

  • bpo-27772: In string formatting, preceding the width field by '0' no longer affects the default alignment for strings.

Library

  • bpo-43108: Fixed a reference leak in the curses module. Patch by Pablo Galindo

  • bpo-43077: Update the bundled pip to 21.0.1 and setuptools to 52.0.0.

  • bpo-41282: Deprecate distutils in documentation and add warning on import.

  • bpo-43014: Improve performance of tokenize by 20-30%. Patch by Anthony Sottile.

  • bpo-42323: Fix math.nextafter() for NaN on AIX.

  • bpo-42955: Add sys.stdlib_module_names, containing the list of the standard library module names. Patch by Victor Stinner.

  • bpo-42944: Fix random.Random.sample when counts argument is not None.

  • bpo-42934: Use TracebackException’s new compact param in TestResult to reduce time and memory consumed by traceback formatting.

  • bpo-42931: Add randbytes() to random.__all__.

  • bpo-38250: [Enum] Flags consisting of a single bit are now considered canonical, and will be the only flags returned from listing and iterating over a Flag class or a Flag member. Multi-bit flags are considered aliases; they will be returned from lookups and operations that result in their value. Iteration for both Flag and Flag members is in definition order.

  • bpo-42877: Added the compact parameter to the constructor of traceback.TracebackException to reduce time and memory for use cases that only need to call TracebackException.format() and TracebackException.format_exception_only().

  • bpo-42923: The Py_FatalError() function and the faulthandler module now dump the list of extension modules on a fatal error.

  • bpo-42848: Removed recursion from TracebackException to allow it to handle long exception chains.

  • bpo-42901: [Enum] move member creation from EnumMeta.__new__ to _proto_member.__set_name__, allowing members to be created and visible in __init_subclass__.

  • bpo-42780: Fix os.set_inheritable() for O_PATH file descriptors on Linux.

  • bpo-42866: Fix a reference leak in the getcodec() function of CJK codecs. Patch by Victor Stinner.

  • bpo-42846: Convert the 6 CJK codec extension modules (_codecs_cn, _codecs_hk, _codecs_iso2022, _codecs_jp, _codecs_kr and _codecs_tw) to the multiphase initialization API (PEP 489). Patch by Victor Stinner.

  • bpo-42851: remove __init_subclass__ support for Enum members

  • bpo-42834: Make internal caches of the _json module compatible with subinterpreters.

  • bpo-41748: Fix HTMLParser parsing rules for element attributes containing commas with spaces. Patch by Karl Dubost.

  • bpo-40810: Require SQLite 3.7.15 or newer. Patch by Erlend E. Aasland.

  • bpo-1635741: Convert the _multibytecodec extension module (CJK codecs) to multi-phase initialization (PEP 489). Patch by Erlend E. Aasland.

  • bpo-42802: The distutils bdist_wininst command deprecated in Python 3.8 has been removed. The distutils bdist_wheel command is now recommended to distribute binary packages on Windows.

  • bpo-24464: The undocumented built-in function sqlite3.enable_shared_cache is now deprecated, scheduled for removal in Python 3.12. Its use is strongly discouraged by the SQLite3 documentation. Patch by Erlend E. Aasland.

  • bpo-42384: Make pdb populate sys.path[0] exactly the same as regular python execution.

  • bpo-42383: Fix pdb: previously pdb would fail to restart the debugging target if it was specified using a relative path and the current directory changed.

  • bpo-42005: Fix CLI of cProfile and profile to catch BrokenPipeError.

  • bpo-41604: Don’t decrement the reference count of the previous user_ptr when set_panel_userptr fails.

  • bpo-41149: Allow executing callables that have a boolean value of False when passed to Threading.thread as the target. Patch contributed by Barney Stratford.

  • bpo-38307: Add an ‘end_lineno’ attribute to the Class and Function objects that appear in the tree returned by pyclbr functions. This and the existing ‘lineno’ attribute define the extent of class and def statements. Patch by Aviral Srivastava.

  • bpo-39273: The BUTTON5_* constants are now exposed in the curses module if available.

  • bpo-33289: Correct call to tkinter.colorchooser to return RGB triplet of ints instead of floats. Patch by Cheryl Sabella.

Documentation

  • bpo-40304: Fix doc for type(name, bases, dict). Patch by Boris Verkhovskiy and Éric Araujo.

  • bpo-42811: Updated importlib.utils.resolve_name() doc to use __spec__.parent instead of __package__. (Thanks Yair Frid.)

Tests

  • bpo-40823: Use unittest.TestLoader().loadTestsFromTestCase() instead of unittest.makeSuite() in sqlite3 tests. Patch by Erlend E. Aasland.

  • bpo-40810: In sqlite3, fix CheckTraceCallbackContent for SQLite pre 3.7.15.

Build

  • bpo-43031: Pass --timeout=$(TESTTIMEOUT) option to the default profile task ./python -m test --pgo command.

  • bpo-36143: make regen-all now also runs regen-keyword. Patch by Victor Stinner.

  • bpo-42874: Removed the grep -q and -E flags in the tzpath validation section of the configure script to better accommodate users of some platforms (specifically Solaris 10).

  • bpo-31904: Add library search path by wr-cc in add_cross_compiling_paths() for VxWorks.

  • bpo-42856: Add --with-wheel-pkg-dir=PATH option to the ./configure script. If specified, the ensurepip module looks for setuptools and pip wheel packages in this directory: if both are present, these wheel packages are used instead of ensurepip bundled wheel packages.

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

Windows

  • bpo-41837: Updated Windows installer to include OpenSSL 1.1.1i

  • bpo-42584: Upgrade Windows installer to use SQLite 3.34.0.

macOS

  • bpo-42504: Ensure that the value of sysconfig.get_config_var(‘MACOSX_DEPLOYMENT_TARGET’) is always a string, even in when the value is parsable as an integer.

IDLE

  • bpo-43008: Make IDLE invoke sys.excepthook() in normal, 2-process mode. Patch by Ken Hilton.

  • bpo-33065: Fix problem debugging user classes with __repr__ method.

  • bpo-23544: Disable Debug=>Stack Viewer when user code is running or Debugger is active, to prevent hang or crash. Patch by Zackery Spytz.

  • bpo-32631: Finish zzdummy example extension module: make menu entries work; add docstrings and tests with 100% coverage.

C API

  • bpo-42979: When Python is built in debug mode (with C assertions), calling a type slot like sq_length (__len__() in Python) now fails with a fatal error if the slot succeeded with an exception set, or failed with no exception set. The error message contains the slot, the type name, and the current exception (if an exception is set). Patch by Victor Stinner.

  • bpo-43030: Fixed a compiler warning in Py_UNICODE_ISSPACE() on platforms with signed wchar_t.

Python 3.10.0 alpha 4

Release date: 2021-01-04

Core and Builtins

  • bpo-42814: Fix undefined behavior in Objects/genericaliasobject.c.

  • bpo-42806: Fix the column offsets for f-strings ast nodes surrounded by parentheses and for nodes that spawn multiple lines. Patch by Pablo Galindo.

  • bpo-40631: Fix regression where a single parenthesized starred expression was a valid assignment target.

  • bpo-27794: Improve the error message for failed writes/deletes to property objects. When possible, the attribute name is now shown. Patch provided by Yurii Karabas.

  • bpo-42745: Make the type attribute lookup cache per-interpreter. Patch by Victor Stinner.

  • bpo-42246: Jumps to jumps are not eliminated when it would break PEP 626.

  • bpo-42246: Make sure that the f_lasti and f_lineno attributes of a frame are set correctly when an exception is raised or re-raised. Required for PEP 626.

  • bpo-32381: The coding cookie (ex: # coding: latin1) is now ignored in the command passed to the -c command line option. Patch by Victor Stinner.

  • bpo-30858: Improve error location in expressions that contain assignments. Patch by Pablo Galindo and Lysandros Nikolaou.

  • bpo-42615: Remove jump commands made redundant by the deletion of unreachable bytecode blocks

  • bpo-42639: Make the atexit module state per-interpreter. It is now safe have more than one atexit module instance. Patch by Donghee Na and Victor Stinner.

  • bpo-32381: Fix encoding name when running a .pyc file on Windows: PyRun_SimpleFileExFlags() now uses the correct encoding to decode the filename.

  • bpo-42195: The __args__ of the parameterized generics for typing.Callable and collections.abc.Callable are now consistent. The __args__ for collections.abc.Callable are now flattened while typing.Callable’s have not changed. To allow this change, types.GenericAlias can now be subclassed and collections.abc.Callable’s __class_getitem__ will now return a subclass of types.GenericAlias. Tests for typing were also updated to not subclass things like Callable[..., T] as that is not a valid base class. Finally, both Callables no longer validate their argtypes, in Callable[[argtypes], resulttype] to prepare for PEP 612. Patch by Ken Jin.

  • bpo-40137: Convert functools module to use PyType_FromModuleAndSpec().

  • bpo-40077: Convert array to use heap types, and establish module state for these.

  • bpo-42008: Fix _random.Random() seeding.

  • bpo-1635741: Port the pyexpat extension module to multi-phase initialization (PEP 489).

  • bpo-40521: Make the Unicode dictionary of interned strings compatible with subinterpreters. Patch by Victor Stinner.

  • bpo-39465: Make _PyUnicode_FromId() function compatible with subinterpreters. Each interpreter now has an array of identifier objects (interned strings decoded from UTF-8). Patch by Victor Stinner.

Library

  • bpo-42257: Handle empty string in variable executable in platform.libc_ver()

  • bpo-42772: randrange() now raises a TypeError when step is specified without a stop argument. Formerly, it silently ignored the step argument.

  • bpo-42759: Fixed equality comparison of tkinter.Variable and tkinter.font.Font. Objects which belong to different Tcl interpreters are now always different, even if they have the same name.

  • bpo-42756: Configure LMTP Unix-domain socket to use socket global default timeout when a timeout is not explicitly provided.

  • bpo-23328: Allow / character in username, password fields on _PROXY envars.

  • bpo-42740: typing.get_args() and typing.get_origin() now support PEP 604 union types and PEP 612 additions to Callable.

  • bpo-42655: subprocess extra_groups is now correctly passed into setgroups() system call.

  • bpo-42727: EnumMeta.__prepare__ now accepts **kwds to properly support __init_subclass__

  • bpo-38308: Add optional weights to statistics.harmonic_mean().

  • bpo-42721: When simple query dialogs (tkinter.simpledialog), message boxes (tkinter.messagebox) or color choose dialog (tkinter.colorchooser) are created without arguments master and parent, and the default root window is not yet created, and NoDefaultRoot() was not called, a new temporal hidden root window will be created automatically. It will not be set as the default root window and will be destroyed right after closing the dialog window. It will help to use these simple dialog windows in programs which do not need other GUI.

  • bpo-25246: Optimized collections.deque.remove().

  • bpo-35728: Added a root parameter to tkinter.font.nametofont().

  • bpo-15303: tkinter supports now widgets with boolean value False.

  • bpo-42681: Fixed range checks for color and pair numbers in curses.

  • bpo-42685: Improved placing of simple query windows in Tkinter (such as tkinter.simpledialog.askinteger()). They are now centered at the center of the parent window if it is specified and shown, otherwise at the center of the screen.

  • bpo-9694: Argparse help no longer uses the confusing phrase, “optional arguments”. It uses “options” instead.

  • bpo-1635741: Port the _thread extension module to the multiphase initialization API (PEP 489) and convert its static types to heap types.

  • bpo-37961: Fix crash in tracemalloc.Traceback.__repr__() (regressed in Python 3.9).

  • bpo-42630: tkinter functions and constructors which need a default root window raise now RuntimeError with descriptive message instead of obscure AttributeError or NameError if it is not created yet or cannot be created automatically.

  • bpo-42639: atexit._run_exitfuncs() now logs callback exceptions using sys.unraisablehook, rather than logging them directly into sys.stderr and raise the last exception.

  • bpo-42644: logging.disable will now validate the types and value of its parameter. It also now accepts strings representing the levels (as does loging.setLevel) instead of only the numerical values.

  • bpo-42639: At Python exit, if a callback registered with atexit.register() fails, its exception is now logged. Previously, only some exceptions were logged, and the last exception was always silently ignored.

  • bpo-36541: Fixed lib2to3.pgen2 to be able to parse PEP-570 positional only argument syntax.

  • bpo-42382: In importlib.metadata: - EntryPoint objects now expose a .dist object referencing the Distribution when constructed from a Distribution. - Add support for package discovery under package normalization rules. - The object returned by metadata() now has a formally defined protocol called PackageMetadata with declared support for the .get_all() method. - Synced with importlib_metadata 3.3.

  • bpo-41877: A check is added against misspellings of autospect, auto_spec and set_spec being passed as arguments to patch, patch.object and create_autospec.

  • bpo-39717: [tarfile] update nested exception raising to use from None or from e

  • bpo-41877: AttributeError for suspected misspellings of assertions on mocks are now pointing out that the cause are misspelled assertions and also what to do if the misspelling is actually an intended attribute name. The unittest.mock document is also updated to reflect the current set of recognised misspellings.

  • bpo-41559: Implemented PEP 612: added ParamSpec and Concatenate to typing. Patch by Ken Jin.

  • bpo-42385: StrEnum: fix _generate_next_value_ to return a str

  • bpo-31904: Define THREAD_STACK_SIZE for VxWorks.

  • bpo-34750: [Enum] _EnumDict.update() is now supported.

  • bpo-42517: Enum: private names do not become members / do not generate errors – they remain normal attributes

  • bpo-42678: Enum: call __init_subclass__ after members have been added

  • bpo-28964: ast.literal_eval() adds line number information (if available) in error message for malformed nodes.

  • bpo-42470: random.sample() no longer warns on a sequence which is also a set.

  • bpo-31904: posixpath.expanduser() returns the input path unchanged if user home directory is None on VxWorks.

  • bpo-42388: Fix subprocess.check_output(…, input=None) behavior when text=True to be consistent with that of the documentation and universal_newlines=True.

  • bpo-34463: Fixed discrepancy between traceback and the interpreter in formatting of SyntaxError with lineno not set (traceback was changed to match interpreter).

  • bpo-42393: Raise OverflowError instead of silent truncation in socket.ntohs() and socket.htons(). Silent truncation was deprecated in Python 3.7. Patch by Erlend E. Aasland

  • bpo-42222: Harmonized random.randrange() argument handling to match range().

    • The integer test and conversion in randrange() now uses operator.index().

    • Non-integer arguments to randrange() are deprecated.

    • The ValueError is deprecated in favor of a TypeError.

    • It now runs a little faster than before.

    (Contributed by Raymond Hettinger and Serhiy Storchaka.)

  • bpo-42163: Restore compatibility for uname_result around deepcopy and _replace.

  • bpo-42090: zipfile.Path.joinpath now accepts arbitrary arguments, same as pathlib.Path.joinpath.

  • bpo-1635741: Port the _csv module to the multi-phase initialization API (PEP 489).

  • bpo-42059: typing.TypedDict types created using the alternative call-style syntax now correctly respect the total keyword argument when setting their __required_keys__ and __optional_keys__ class attributes.

  • bpo-41960: Add globalns and localns parameters to the inspect.signature() and inspect.Signature.from_callable().

  • bpo-41907: fix format() behavior for IntFlag

  • bpo-41891: Ensure asyncio.wait_for waits for task completion

  • bpo-24792: Fixed bug where zipimporter sometimes reports an incorrect cause of import errors.

  • bpo-31904: Fix site and sysconfig modules for VxWorks RTOS which has no home directories.

  • bpo-41462: Add os.set_blocking() support for VxWorks RTOS.

  • bpo-40219: Lowered tkinter.ttk.LabeledScale dummy widget to prevent hiding part of the content label.

  • bpo-37193: Fixed memory leak in socketserver.ThreadingMixIn introduced in Python 3.7.

  • bpo-39068: Fix initialization race condition in a85encode() and b85encode() in base64. Patch by Brandon Stansbury.

Documentation

Tests

  • bpo-42794: Update test_nntplib to use official group name of news.aioe.org for testing. Patch by Donghee Na.

  • bpo-31904: Skip some asyncio tests on VxWorks.

  • bpo-42641: Enhance test_select.test_select(): it now takes 500 milliseconds rather than 10 seconds. Use Python rather than a shell to make the test more portable.

  • bpo-31904: Skip some tests in _test_all_chown_common() on VxWorks.

  • bpo-42199: Fix bytecode helper assertNotInBytecode.

  • bpo-41443: Add more attribute checking in test_posix.py

  • bpo-31904: Disable os.popen and impacted tests on VxWorks

  • bpo-41439: Port test_ssl and test_uuid to VxWorks RTOS.

Build

  • bpo-42692: Fix __builtin_available check on older compilers. Patch by Joshua Root.

  • bpo-27640: Added --disable-test-modules option to the configure script: don’t build nor install test modules. Patch by Xavier de Gaye, Thomas Petazzoni and Peixing Xin.

  • bpo-42604: Now all platforms use a value for the “EXT_SUFFIX” build variable derived from SOABI (for instance in freeBSD, “EXT_SUFFIX” is now “.cpython-310d.so” instead of “.so”). Previously only Linux, Mac and VxWorks were using a value for “EXT_SUFFIX” that included “SOABI”.

  • bpo-42598: Fix implicit function declarations in configure which could have resulted in incorrect configuration checks. Patch contributed by Joshua Root.

  • bpo-31904: Enable libpython3.so for VxWorks.

  • bpo-29076: Add fish shell support to macOS installer.

macOS

  • bpo-42361: Update macOS installer build to use Tcl/Tk 8.6.11 (rc2, expected to be final release).

  • bpo-41837: Update macOS installer build to use OpenSSL 1.1.1i.

  • bpo-42584: Update macOS installer to use SQLite 3.34.0.

Tools/Demos

  • bpo-42726: Fixed Python 3 compatibility issue with gdb/libpython.py handling of attribute dictionaries.

  • bpo-42613: Fix freeze.py tool to use the prope config and library directories. Patch by Victor Stinner.

C API

  • bpo-42591: Export the Py_FrozenMain() function: fix a Python 3.9.0 regression. Python 3.9 uses -fvisibility=hidden and the function was not exported explicitly and so not exported.

  • bpo-32381: Remove the private _Py_fopen() function which is no longer needed. Use _Py_wfopen() or _Py_fopen_obj() instead. Patch by Victor Stinner.

  • bpo-1635741: Port resource extension module to module state

  • bpo-42111: Update the xxlimited module to be a better example of how to use the limited C API.

  • bpo-40052: Fix an alignment build warning/error in function PyVectorcall_Function(). Patch by Andreas Schneider, Antoine Pitrou and Petr Viktorin.

Python 3.10.0 alpha 3

Release date: 2020-12-07

Security

  • bpo-40791: Add volatile to the accumulator variable in hmac.compare_digest, making constant-time-defeating optimizations less likely.

Core and Builtins

  • bpo-42576: types.GenericAlias will now raise a TypeError when attempting to initialize with a keyword argument. Previously, this would cause the interpreter to crash if the interpreter was compiled with debug symbols. This does not affect interpreters compiled for release. Patch by Ken Jin.

  • bpo-42536: Several built-in and standard library types now ensure that their internal result tuples are always tracked by the garbage collector:

    Previously, they could have become untracked by a prior garbage collection. Patch by Brandt Bucher.

  • bpo-42500: Improve handling of exceptions near recursion limit. Converts a number of Fatal Errors in RecursionErrors.

  • bpo-42246: PEP 626: After a return, the f_lineno attribute of a frame is always the last line executed.

  • bpo-42435: Speed up comparison of bytes objects with non-bytes objects when option -b is specified. Speed up comparison of bytarray objects with non-buffer object.

  • bpo-1635741: Port the _warnings extension module to the multi-phase initialization API (PEP 489). Patch by Victor Stinner.

  • bpo-41686: On Windows, the SIGINT event, _PyOS_SigintEvent(), is now created even if Python is configured to not install signal handlers (if PyConfig.install_signal_handlers equals to 0, or Py_InitializeEx(0)).

  • bpo-42381: Allow assignment expressions in set literals and set comprehensions as per PEP 572. Patch by Pablo Galindo.

  • bpo-42202: Change function parameters annotations internal representation to tuple of strings. Patch provided by Yurii Karabas.

  • bpo-42374: Fix a regression introduced by the new parser, where an unparenthesized walrus operator was not allowed within generator expressions.

  • bpo-42316: Allow an unparenthesized walrus in subscript indexes.

  • bpo-42349: Make sure that the compiler front-end produces a well-formed control flow graph. Be be more aggressive in the compiler back-end, as it is now safe to do so.

  • bpo-42296: On Windows, fix a regression in signal handling which prevented to interrupt a program using CTRL+C. The signal handler can be run in a thread different than the Python thread, in which case the test deciding if the thread can handle signals is wrong.

  • bpo-42332: types.GenericAlias objects can now be the targets of weakrefs.

  • bpo-42282: Optimise constant subexpressions that appear as part of named expressions (previously the AST optimiser did not descend into named expressions). Patch by Nick Coghlan.

  • bpo-42266: Fixed a bug with the LOAD_ATTR opcode cache that was not respecting monkey-patching a class-level attribute to make it a descriptor. Patch by Pablo Galindo.

  • bpo-40077: Convert queue to use heap types.

  • bpo-42246: Improved accuracy of line tracing events and f_lineno attribute of Frame objects. See PEP 626 for details.

  • bpo-40077: Convert mmap to use heap types.

  • bpo-42233: Allow GenericAlias objects to use union type expressions. This allows expressions like list[int] | dict[float, str] where previously a TypeError would have been thrown. This also fixes union type expressions not de-duplicating GenericAlias objects. (Contributed by Ken Jin in bpo-42233.)

  • bpo-26131: The import system triggers a ImportWarning when it falls back to using load_module().

Library

  • bpo-5054: CGIHTTPRequestHandler.run_cgi() HTTP_ACCEPT improperly parsed. Replace the special purpose getallmatchingheaders with generic get_all method and add relevant tests.

    Original Patch by Martin Panter. Modified by Senthil Kumaran.

  • bpo-42562: Fix issue when dis failed to parse function that has no line numbers. Patch provided by Yurii Karabas.

  • bpo-17735: inspect.findsource() now raises OSError instead of IndexError when co_lineno of a code object is greater than the file length. This can happen, for example, when a file is edited after it was imported. PR by Irit Katriel.

  • bpo-42116: Fix handling of trailing comments by inspect.getsource().

  • bpo-42532: Remove unexpected call of __bool__ when passing a spec_arg argument to a Mock.

  • bpo-38200: Added itertools.pairwise()

  • bpo-41818: Fix test_master_read() so that it succeeds on all platforms that either raise OSError or return b”” upon reading from master.

  • bpo-42487: ChainMap.__iter__ no longer calls __getitem__ on underlying maps

  • bpo-42482: TracebackException no longer holds a reference to the exception’s traceback object. Consequently, instances of TracebackException for equivalent but non-equal exceptions now compare as equal.

  • bpo-41818: Make test_openpty() avoid unexpected success due to number of rows and/or number of columns being == 0.

  • bpo-42392: Remove loop parameter from asyncio.subprocess and asyncio.tasks functions. Patch provided by Yurii Karabas.

  • bpo-42392: Remove loop parameter from asyncio.open_connection and asyncio.start_server functions. Patch provided by Yurii Karabas.

  • bpo-28468: Add platform.freedesktop_os_release() function to parse freedesktop.org os-release files.

  • bpo-42299: Removed the formatter module, which was deprecated in Python 3.4. It is somewhat obsolete, little used, and not tested. It was originally scheduled to be removed in Python 3.6, but such removals were delayed until after Python 2.7 EOL. Existing users should copy whatever classes they use into their code. Patch by Donghee Na and and Terry J. Reedy.

  • bpo-26131: Deprecate zipimport.zipimporter.load_module() in favour of exec_module().

  • bpo-41818: Updated tests for the pty library. test_basic() has been changed to test_openpty(); this additionally checks if slave termios and slave winsize are being set properly by pty.openpty(). In order to add support for FreeBSD, NetBSD, OpenBSD, and Darwin, this also adds test_master_read(), which demonstrates that pty.spawn() should not depend on an OSError to exit from its copy loop.

  • bpo-42392: Remove loop parameter from __init__ in all asyncio.locks and asyncio.Queue classes. Patch provided by Yurii Karabas.

  • bpo-15450: Make filecmp.dircmp respect subclassing. Now the filecmp.dircmp.subdirs behaves as expected when subclassing dircmp.

  • bpo-42413: The exception socket.timeout is now an alias of TimeoutError.

  • bpo-31904: Support signal module on VxWorks.

  • bpo-42406: We fixed an issue in pickle.whichmodule in which importing multiprocessing could change the how pickle identifies which module an object belongs to, potentially breaking the unpickling of those objects.

  • bpo-42403: Simplify the importlib external bootstrap code: importlib._bootstrap_external now uses regular imports to import builtin modules. When it is imported, the builtin __import__() function is already fully working and so can be used to import builtin modules like sys. Patch by Victor Stinner.

  • bpo-1635741: Convert _sre module types to heap types (PEP 384). Patch by Erlend E. Aasland.

  • bpo-42375: subprocess module update for DragonFlyBSD support.

  • bpo-41713: Port the _signal extension module to the multi-phase initialization API (PEP 489). Patch by Victor Stinner and Mohamed Koubaa.

  • bpo-37205: time.time(), time.perf_counter() and time.monotonic() functions can no longer fail with a Python fatal error, instead raise a regular Python exception on failure.

  • bpo-42328: Fixed tkinter.ttk.Style.map(). The function accepts now the representation of the default state as empty sequence (as returned by Style.map()). The structure of the result is now the same on all platform and does not depend on the value of wantobjects.

  • bpo-42345: Fix various issues with typing.Literal parameter handling (flatten, deduplicate, use type to cache key). Patch provided by Yurii Karabas.

  • bpo-37205: time.perf_counter() on Windows and time.monotonic() on macOS are now system-wide. Previously, they used an offset computed at startup to reduce the precision loss caused by the float type. Use time.perf_counter_ns() and time.monotonic_ns() added in Python 3.7 to avoid this precision loss.

  • bpo-42318: Fixed support of non-BMP characters in tkinter on macOS.

  • bpo-42350: Fix the threading.Thread class at fork: do nothing if the thread is already stopped (ex: fork called at Python exit). Previously, an error was logged in the child process.

  • bpo-42333: Port _ssl extension module to heap types.

  • bpo-42014: The onerror callback from shutil.rmtree now receives correct function when os.open fails.

  • bpo-42237: Fix os.sendfile() on illumos.

  • bpo-42308: Add threading.__excepthook__ to allow retrieving the original value of threading.excepthook() in case it is set to a broken or a different value. Patch by Mario Corchero.

  • bpo-42131: Implement PEP 451/spec methods on zipimport.zipimporter: find_spec(), create_module(), and exec_module().

    This also allows for the documented deprecation of find_loader(), find_module(), and load_module().

  • bpo-41877: Mock objects which are not unsafe will now raise an AttributeError if an attribute with the prefix asert, aseert, or assrt is accessed, in addition to this already happening for the prefixes assert or assret.

  • bpo-42264: sqlite3.OptimizedUnicode has been undocumented and obsolete since Python 3.3, when it was made an alias to str. It is now deprecated, scheduled for removal in Python 3.12.

  • bpo-42251: Added threading.gettrace() and threading.getprofile() to retrieve the functions set by threading.settrace() and threading.setprofile() respectively. Patch by Mario Corchero.

  • bpo-42249: Fixed writing binary Plist files larger than 4 GiB.

  • bpo-42236: On Unix, the os.device_encoding() function now returns 'UTF-8' rather than the device encoding if the Python UTF-8 Mode is enabled.

  • bpo-41754: webbrowser: Ignore NotADirectoryError when calling xdg-settings.

  • bpo-42183: Fix a stack overflow error for asyncio Task or Future repr().

    The overflow occurs under some circumstances when a Task or Future recursively returns itself.

  • bpo-42140: Improve asyncio.wait function to create the futures set just one time.

  • bpo-42133: Update various modules in the stdlib to fall back on __spec__.loader when __loader__ isn’t defined on a module.

  • bpo-26131: The load_module() methods found in importlib now trigger a DeprecationWarning.

  • bpo-39825: Windows: Change sysconfig.get_config_var('EXT_SUFFIX') to the expected full platform_tag.extension format. Previously it was hard-coded to .pyd, now it is compatible with distutils.sysconfig and will result in something like .cp38-win_amd64.pyd. This brings windows into conformance with the other platforms.

  • bpo-26389: The traceback.format_exception(), traceback.format_exception_only(), and traceback.print_exception() functions can now take an exception object as a positional-only argument.

  • bpo-41889: Enum: fix regression involving inheriting a multiply inherited enum

  • bpo-41861: Convert sqlite3 to use heap types (PEP 384). Patch by Erlend E. Aasland.

  • bpo-40624: Added support for the XPath != operator in xml.etree

  • bpo-28850: Fix pprint.PrettyPrinter.format() overrides being ignored for contents of small containers. The pprint._safe_repr() function was removed.

  • bpo-41625: Expose the splice() as os.splice() in the os module. Patch by Pablo Galindo

  • bpo-34215: Clarify the error message for asyncio.IncompleteReadError when expected is None.

  • bpo-41543: Add async context manager support for contextlib.nullcontext.

  • bpo-21041: pathlib.PurePath.parents now supports negative indexing. Patch contributed by Yaroslav Pankovych.

  • bpo-41332: Added missing connect_accepted_socket() method to asyncio.AbstractEventLoop.

  • bpo-12800: Extracting a symlink from a tarball should succeed and overwrite the symlink if it already exists. The fix is to remove the existing file or symlink before extraction. Based on patch by Chris AtLee, Jeffrey Kintscher, and Senthil Kumaran.

  • bpo-40968: urllib.request and http.client now send http/1.1 ALPN extension during TLS handshake when no custom context is supplied.

  • bpo-41001: Add os.eventfd() to provide a low level interface for Linux’s event notification file descriptor.

  • bpo-40816: Add AsyncContextDecorator to contextlib to support async context manager as a decorator.

  • bpo-40550: Fix time-of-check/time-of-action issue in subprocess.Popen.send_signal.

  • bpo-39411: Add an is_async identifier to pyclbr’s Function objects. Patch by Batuhan Taskaya

  • bpo-35498: Add slice support to pathlib.PurePath.parents.

Documentation

  • bpo-42238: Tentative to deprecate make suspicious by first removing it from the CI and documentation builds, but keeping it around for manual uses.

  • bpo-42153: Fix the URL for the IMAP protocol documents.

  • bpo-41028: Language and version switchers, previously maintained in every cpython branches, are now handled by docsbuild-script.

Tests

  • bpo-41473: Re-enable test_gdb on gdb 9.2 and newer: https://bugzilla.redhat.com/show_bug.cgi?id=1866884 bug is fixed in gdb 10.1.

  • bpo-42553: Fix test_asyncio.test_call_later() race condition: don’t measure asyncio performance in the call_later() unit test. The test failed randomly on the CI.

  • bpo-31904: Fix test_netrc on VxWorks: create temporary directories using temp_cwd().

  • bpo-31904: skip test_getaddrinfo_ipv6_scopeid_symbolic and test_getnameinfo_ipv6_scopeid_symbolic on VxWorks

  • bpo-31904: skip test_test of test_mailcap on VxWorks

  • bpo-31904: add shell requirement for test_pipes

  • bpo-31904: skip some tests related to fifo on VxWorks

  • bpo-31904: Fix test_doctest.py failures for VxWorks.

  • bpo-40754: Include _testinternalcapi module in Windows installer for test suite

  • bpo-41561: test_ssl: skip test_min_max_version_mismatch when TLS 1.0 is not available

  • bpo-31904: Fix os module failures for VxWorks RTOS.

  • bpo-31904: Fix fifo test cases for VxWorks RTOS.

Build

  • bpo-31904: remove libnet dependency from detect_socket() for VxWorks

  • bpo-42398: Fix a race condition in “make regen-all” when make -jN option is used to run jobs in parallel. The clinic.py script now only use atomic write to write files. Moveover, generated files are now left unchanged if the content does not change, to not change the file modification time.

  • bpo-41617: Fix building pycore_bitutils.h internal header on old clang version without __builtin_bswap16() (ex: Xcode 4.6.3 on Mac OS X 10.7). Patch by Joshua Root and Victor Stinner.

  • bpo-38823: It is no longer possible to build the _ctypes extension module without wchar_t type: remove CTYPES_UNICODE macro. Anyway, the wchar_t type is required to build Python. Patch by Victor Stinner.

  • bpo-42087: Support was removed for AIX 5.3 and below. See bpo-40680.

  • bpo-40998: Addressed three compiler warnings found by undefined behavior sanitizer (ubsan).

Windows

  • bpo-42120: Remove macro definition of copysign (to _copysign) in headers.

  • bpo-38506: The Windows launcher now properly handles Python 3.10 when listing installed Python versions.

macOS

  • bpo-42504: Fix build on macOS Big Sur when MACOSX_DEPLOYMENT_TARGET=11

  • bpo-41116: Ensure distutils.unixxcompiler.find_library_file can find system provided libraries on macOS 11.

  • bpo-41100: Add support for macOS 11 and Apple Silicon systems.

    It is now possible to build “Universal 2” binaries using “–enable-universalsdk –with-universal-archs=universal2”.

    Binaries build on later macOS versions can be deployed back to older versions (tested up to macOS 10.9), when using the correct deployment target. This is tested using Xcode 11 and later.

  • bpo-42232: Added Darwin specific madvise options to mmap module.

  • bpo-38443: The --enable-universalsdk and --with-universal-archs options for the configure script now check that the specified architectures can be used.

IDLE

  • bpo-42508: Keep IDLE running on macOS. Remove obsolete workaround that prevented running files with shortcuts when using new universal2 installers built on macOS 11.

  • bpo-42426: Fix reporting offset of the RE error in searchengine.

  • bpo-42415: Get docstrings for IDLE calltips more often by using inspect.getdoc.

Tools/Demos

  • bpo-42212: The smelly.py script now also checks the Python dynamic library and extension modules, not only the Python static library. Make also the script more verbose: explain what it does.

  • bpo-36310: Allow Tools/i18n/pygettext.py to detect calls to gettext in f-strings.

C API

Python 3.10.0 alpha 2

Release date: 2020-11-03

Security

  • bpo-42103: Prevented potential DoS attack via CPU and RAM exhaustion when processing malformed Apple Property List files in binary format.

  • bpo-42051: The plistlib module no longer accepts entity declarations in XML plist files to avoid XML vulnerabilities. This should not affect users as entity declarations are not used in regular plist files.

Core and Builtins

  • bpo-42236: If the nl_langinfo(CODESET) function returns an empty string, Python now uses UTF-8 as the filesystem encoding. Patch by Victor Stinner.

  • bpo-42218: Fixed a bug in the PEG parser that was causing crashes in debug mode. Now errors are checked in left-recursive rules to avoid cases where such errors do not get handled in time and appear as long-distance crashes in other places.

  • bpo-42214: Fixed a possible crash in the PEG parser when checking for the ‘!=’ token in the barry_as_flufl rule. Patch by Pablo Galindo.

  • bpo-42206: Propagate and raise the errors caused by PyAST_Validate() in the parser.

  • bpo-41796: The ast module internal state is now per interpreter. Patch by Victor Stinner.

  • bpo-42143: Fix handling of errors during creation of PyFunctionObject, which resulted in operations on uninitialized memory. Patch by Yonatan Goldschmidt.

  • bpo-41659: Fix a bug in the parser, where a curly brace following a primary didn’t fail immediately. This led to invalid expressions like a {b} to throw a SyntaxError with a wrong offset, or invalid expressions ending with a curly brace like a { to not fail immediately in the REPL.

  • bpo-42150: Fix possible buffer overflow in the new parser when checking for continuation lines. Patch by Pablo Galindo.

  • bpo-42123: Run the parser two times. On the first run, disable all the rules that only generate better error messages to gain performance. If there’s a parse failure, run the parser a second time with those enabled.

  • bpo-42093: The LOAD_ATTR instruction now uses new “per opcode cache” mechanism and it is about 36% faster now. Patch by Pablo Galindo and Yury Selivanov.

  • bpo-42030: Support for the legacy AIX-specific shared library loading support has been removed. All versions of AIX since 4.3 have supported and defaulted to using the common Unix mechanism instead.

  • bpo-41984: The garbage collector now tracks all user-defined classes. Patch by Brandt Bucher.

  • bpo-41993: Fixed potential issues with removing not completely initialized module from sys.modules when import fails.

  • bpo-41979: Star-unpacking is now allowed for with item’s targets in the PEG parser.

  • bpo-41974: Removed special methods __int__, __float__, __floordiv__, __mod__, __divmod__, __rfloordiv__, __rmod__ and __rdivmod__ of the complex class. They always raised a TypeError.

  • bpo-41902: Micro optimization when compute sq_item and mp_subscript of range. Patch by Donghee Na.

  • bpo-41894: When loading a native module and a load failure occurs, prevent a possible UnicodeDecodeError when not running in a UTF-8 locale by decoding the load error message using the current locale’s encoding.

  • bpo-41902: Micro optimization for range.index if step is 1. Patch by Donghee Na.

  • bpo-41435: Add sys._current_exceptions() function to retrieve a dictionary mapping each thread’s identifier to the topmost exception currently active in that thread at the time the function is called.

  • bpo-38605: Enable from __future__ import annotations (PEP 563) by default. The values found in __annotations__ dicts are now strings, e.g. {"x": "int"} instead of {"x": int}.

Library

  • bpo-35455: On Solaris, thread_time() is now implemented with gethrvtime() because clock_gettime(CLOCK_THREAD_CPUTIME_ID) is not always available. Patch by Jakub Kulik.

  • bpo-42233: The repr() of typing types containing Generic Alias Types previously did not show the parameterized types in the GenericAlias. They have now been changed to do so.

  • bpo-29566: binhex.binhex() consistently writes macOS 9 line endings.

  • bpo-26789: The logging.FileHandler class now keeps a reference to the builtin open() function to be able to open or reopen the file during Python finalization. Fix errors like: NameError: name 'open' is not defined. Patch by Victor Stinner.

  • bpo-42157: Removed the unicodedata.ucnhash_CAPI attribute which was an internal PyCapsule object. The related private _PyUnicode_Name_CAPI structure was moved to the internal C API. Patch by Victor Stinner.

  • bpo-42157: Convert the unicodedata extension module to the multiphase initialization API (PEP 489) and convert the unicodedata.UCD static type to a heap type. Patch by Mohamed Koubaa and Victor Stinner.

  • bpo-42146: Fix memory leak in subprocess.Popen() in case an uid (gid) specified in user (group, extra_groups) overflows uid_t (gid_t).

  • bpo-42103: InvalidFileException and RecursionError are now the only errors caused by loading malformed binary Plist file (previously ValueError and TypeError could be raised in some specific cases).

  • bpo-41490: In importlib.resources, .path method is more aggressive about releasing handles to zipfile objects early, enabling use-cases like certifi to leave the context open but delete the underlying zip file.

  • bpo-41052: Pickling heap types implemented in C with protocols 0 and 1 raises now an error instead of producing incorrect data.

  • bpo-42089: In importlib.metadata.PackageNotFoundError, make reference to the package metadata being missing to improve the user experience.

  • bpo-41491: plistlib: fix parsing XML plists with hexadecimal integer values

  • bpo-42065: Fix an incorrectly formatted error from _codecs.charmap_decode() when called with a mapped value outside the range of valid Unicode code points. PR by Max Bernstein.

  • bpo-41966: Fix pickling pure Python datetime.time subclasses. Patch by Dean Inwood.

  • bpo-19270: sched.scheduler.cancel() will now cancel the correct event, if two events with same priority are scheduled for the same time. Patch by Bar Harel.

  • bpo-28660: textwrap.wrap() now attempts to break long words after hyphens when break_long_words=True and break_on_hyphens=True.

  • bpo-35823: Use vfork() instead of fork() for subprocess.Popen() on Linux to improve performance in cases where it is deemed safe.

  • bpo-42043: Add support for zipfile.Path inheritance. zipfile.Path.is_file() now returns False for non-existent names. zipfile.Path objects now expose a .filename attribute and rely on that to resolve .name and .parent when the Path object is at the root of the zipfile.

  • bpo-42021: Fix possible ref leaks in sqlite3 module init.

  • bpo-39101: Fixed tests using IsolatedAsyncioTestCase from hanging on BaseExceptions.

  • bpo-41976: Fixed a bug that was causing ctypes.util.find_library() to return None when triying to locate a library in an environment when gcc>=9 is available and ldconfig is not. Patch by Pablo Galindo

  • bpo-41943: Fix bug where TestCase.assertLogs doesn’t correctly filter messages by level.

  • bpo-41923: Implement PEP 613, introducing typing.TypeAlias annotation.

  • bpo-41905: A new function in abc: update_abstractmethods to re-calculate an abstract class’s abstract status. In addition, dataclass has been changed to call this function.

  • bpo-23706: Added newline parameter to pathlib.Path.write_text().

  • bpo-41876: Tkinter font class repr uses font name

  • bpo-41831: str() for the type attribute of the tkinter.Event object always returns now the numeric code returned by Tk instead of the name of the event type.

  • bpo-39337: encodings.normalize_encoding() now ignores non-ASCII characters.

  • bpo-41747: Ensure all methods that generated from dataclasses.dataclass() objects now have the proper __qualname__ attribute referring to the class they belong to. Patch by Batuhan Taskaya.

  • bpo-30681: Handle exceptions caused by unparsable date headers when using email “default” policy. Patch by Tim Bell, Georges Toth

  • bpo-41586: Add F_SETPIPE_SZ and F_GETPIPE_SZ to fcntl module. Allow setting pipesize on subprocess.Popen.

  • bpo-41229: Add contextlib.aclosing for deterministic cleanup of async generators which is analogous to contextlib.closing for non-async generators. Patch by Joongi Kim and John Belmonte.

  • bpo-16396: Allow ctypes.wintypes to be imported on non-Windows systems.

  • bpo-4356: Add a key function to the bisect module.

  • bpo-40592: shutil.which() now ignores empty entries in PATHEXT instead of treating them as a match.

  • bpo-40492: Fix --outfile for cProfile / profile not writing the output file in the original directory when the program being profiled changes the working directory. PR by Anthony Sottile.

  • bpo-34204: The shelve module now uses pickle.DEFAULT_PROTOCOL by default instead of pickle protocol 3.

  • bpo-27321: Fixed KeyError exception when flattening an email to a string attempts to replace a non-existent Content-Transfer-Encoding header.

  • bpo-38976: The http.cookiejar module now supports the parsing of cookies in CURL-style cookiejar files through MozillaCookieJar on all platforms. Previously, such cookie entries would be silently ignored when loading a cookiejar with such entries.

    Additionally, the HTTP Only attribute is persisted in the object, and will be correctly written to file if the MozillaCookieJar object is subsequently dumped.

Documentation

  • bpo-42061: Document __format__ functionality for IP addresses.

  • bpo-41910: Document the default implementation of object.__eq__.

  • bpo-42010: Clarify that subscription expressions are also valid for certain classes and types in the standard library, and for user-defined classes and types if the classmethod __class_getitem__() is provided.

  • bpo-41805: Documented generic alias type and types.GenericAlias. Also added an entry in glossary for generic types.

  • bpo-39693: Fix tarfile’s extractfile documentation

  • bpo-39416: Document some restrictions on the default string representations of numeric classes.

Tests

  • bpo-41739: Fix test_logging.test_race_between_set_target_and_flush(): the test now waits until all threads complete to avoid leaking running threads.

  • bpo-41970: Avoid a test failure in test_lib2to3 if the module has already imported at the time the test executes. Patch by Pablo Galindo.

  • bpo-41944: Tests for CJK codecs no longer call eval() on content received via HTTP.

  • bpo-41306: Fixed a failure in test_tk.test_widgets.ScaleTest happening when executing the test with Tk 8.6.10.

Build

  • bpo-38980: Add -fno-semantic-interposition to both the compile and link line when building with --enable-optimizations. Patch by Victor Stinner and Pablo Galindo.

Windows

  • bpo-38439: Updates the icons for IDLE in the Windows Store package.

  • bpo-38252: Use 8-byte step to detect ASCII sequence in 64-bit Windows build.

  • bpo-39107: Update Tcl and Tk to 8.6.10 in Windows installer.

  • bpo-41557: Update Windows installer to use SQLite 3.33.0.

  • bpo-38324: Avoid Unicode errors when accessing certain locale data on Windows.

macOS

  • bpo-41471: Ignore invalid prefix lengths in system proxy excludes.

IDLE

  • bpo-33987: Mostly finish using ttk widgets, mainly for editor, settings, and searches. Some patches by Mark Roseman.

  • bpo-40511: Typing opening and closing parentheses inside the parentheses of a function call will no longer cause unnecessary “flashing” off and on of an existing open call-tip, e.g. when typed in a string literal.

  • bpo-38439: Add a 256×256 pixel IDLE icon to the Windows .ico file. Created by Andrew Clover. Remove the low-color gif variations from the .ico file.

C API

  • bpo-42157: The private _PyUnicode_Name_CAPI structure of the PyCapsule API unicodedata.ucnhash_CAPI has been moved to the internal C API. Patch by Victor Stinner.

  • bpo-42015: Fix potential crash in deallocating method objects when dynamically allocated PyMethodDef’s lifetime is managed through the self argument of a PyCFunction.

  • bpo-40423: The subprocess module and os.closerange will now use the close_range(low, high, flags) syscall when it is available for more efficient closing of ranges of descriptors.

  • bpo-41845: PyObject_GenericGetDict() is available again in the limited API when targeting 3.10 or later.

  • bpo-40422: Add _Py_closerange function to provide performant closing of a range of file descriptors.

  • bpo-41986: Py_FileSystemDefaultEncodeErrors and Py_UTF8Mode are available again in limited API.

  • bpo-41756: Add PyIter_Send function to allow sending value into generator/coroutine/iterator without raising StopIteration exception to signal return.

  • bpo-41784: Added PyUnicode_AsUTF8AndSize to the limited C API.

Python 3.10.0 alpha 1

Release date: 2020-10-05

Security

  • bpo-41304: Fixes python3x._pth being ignored on Windows, caused by the fix for bpo-29778 (CVE-2020-15801).

  • bpo-41162: Audit hooks are now cleared later during finalization to avoid missing events.

  • bpo-29778: Ensure python3.dll is loaded from correct locations when Python is embedded (CVE-2020-15523).

  • bpo-41004: The __hash__() methods of ipaddress.IPv4Interface and ipaddress.IPv6Interface incorrectly generated constant hash values of 32 and 128 respectively. This resulted in always causing hash collisions. The fix uses hash() to generate hash values for the tuple of (address, mask length, network address).

  • bpo-39603: Prevent http header injection by rejecting control characters in http.client.putrequest(…).

Core and Builtins

  • bpo-41909: Fixed stack overflow in issubclass() and isinstance() when getting the __bases__ attribute leads to infinite recursion.

  • bpo-41922: Speed up calls to reversed() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-41873: Calls to float() are now faster due to the vectorcall calling convention. Patch by Dennis Sweeney.

  • bpo-41870: Speed up calls to bool() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-1635741: Port the _bisect module to the multi-phase initialization API (PEP 489).

  • bpo-39934: Correctly count control blocks in ‘except’ in compiler. Ensures that a syntax error, rather a fatal error, occurs for deeply nested, named exception handlers.

  • bpo-41780: Fix __dir__() of types.GenericAlias. Patch by Batuhan Taskaya.

  • bpo-1635741: Port the _lsprof extension module to multi-phase initialization (PEP 489).

  • bpo-1635741: Port the cmath extension module to multi-phase initialization (PEP 489).

  • bpo-1635741: Port the _scproxy extension module to multi-phase initialization (PEP 489).

  • bpo-1635741: Port the termios extension module to multi-phase initialization (PEP 489).

  • bpo-1635741: Convert the _sha256 extension module types to heap types.

  • bpo-41690: Fix a possible stack overflow in the parser when parsing functions and classes with a huge amount of arguments. Patch by Pablo Galindo.

  • bpo-1635741: Port the _overlapped extension module to multi-phase initialization (PEP 489).

  • bpo-1635741: Port the _curses_panel extension module to multi-phase initialization (PEP 489).

  • bpo-1635741: Port the _opcode extension module to multi-phase initialization (PEP 489).

  • bpo-41681: Fixes the wrong error description in the error raised by using 2 , in format string in f-string and str.format().

  • bpo-41675: The implementation of signal.siginterrupt() now uses sigaction() (if it is available in the system) instead of the deprecated siginterrupt(). Patch by Pablo Galindo.

  • bpo-41670: Prevent line trace being skipped on platforms not compiled with USE_COMPUTED_GOTOS. Fixes issue where some lines nested within a try-except block were not being traced on Windows.

  • bpo-41654: Fix a crash that occurred when destroying subclasses of MemoryError. Patch by Pablo Galindo.

  • bpo-1635741: Port the zlib extension module to multi-phase initialization (PEP 489).

  • bpo-41631: The _ast module uses again a global state. Using a module state per module instance is causing subtle practical problems. For example, the Mercurial project replaces the __import__() function to implement lazy import, whereas Python expected that import _ast always return a fully initialized _ast module.

  • bpo-40077: Convert _operator to use PyType_FromSpec().

  • bpo-1653741: Port _sha3 to multi-phase init. Convert static types to heap types.

  • bpo-1635741: Port the _blake2 extension module to the multi-phase initialization API (PEP 489).

  • bpo-41533: Free the stack allocated in va_build_stack if do_mkstack fails and the stack is not a small_stack.

  • bpo-41531: Fix a bug that was dropping keys when compiling dict literals with more than 0xFFFF elements. Patch by Pablo Galindo.

  • bpo-41525: The output of python --help contains now only ASCII characters.

  • bpo-1635741: Port the _sha1, _sha512, and _md5 extension modules to multi-phase initialization API (PEP 489).

  • bpo-41431: Optimize dict_merge() for copying dict (e.g. dict(d) and {}.update(d)).

  • bpo-41428: Implement PEP 604. This supports (int | str) etc. in place of Union[str, int].

  • bpo-41340: Removed fallback implementation for strdup.

  • bpo-38156: Handle interrupts that come after EOF correctly in PyOS_StdioReadline.

  • bpo-41342: round() with integer argument is now faster (9–60%).

  • bpo-41334: Constructors str(), bytes() and bytearray() are now faster (around 30–40% for small objects).

  • bpo-41295: Resolve a regression in CPython 3.8.4 where defining “__setattr__” in a multi-inheritance setup and calling up the hierarchy chain could fail if builtins/extension types were involved in the base types.

  • bpo-41323: Bytecode optimizations are performed directly on the control flow graph. This will result in slightly more compact code objects in some circumstances.

  • bpo-41247: Always cache the running loop holder when running asyncio.set_running_loop.

  • bpo-41252: Fix incorrect refcounting in _ssl.c’s _servername_callback().

  • bpo-1635741: Port multiprocessing to multi-phase initialization

  • bpo-1635741: Port winapi to multiphase initialization

  • bpo-41215: Use non-NULL default values in the PEG parser keyword list to overcome a bug that was preventing Python from being properly compiled when using the XLC compiler. Patch by Pablo Galindo.

  • bpo-41218: Python 3.8.3 had a regression where compiling with ast.PyCF_ALLOW_TOP_LEVEL_AWAIT would aggressively mark list comprehension with CO_COROUTINE. Now only list comprehension making use of async/await will tagged as so.

  • bpo-1635741: Port faulthandler to multiphase initialization.

  • bpo-1635741: Port sha256 to multiphase initialization

  • bpo-41175: Guard against a NULL pointer dereference within bytearrayobject triggered by the bytearray() + bytearray() operation.

  • bpo-41100: add arm64 to the allowable Mac OS arches in mpdecimal.h

  • bpo-41094: Fix decoding errors with audit when open files with non-ASCII names on non-UTF-8 locale.

  • bpo-39960: The “hackcheck” that prevents sneaking around a type’s __setattr__() by calling the superclass method was rewritten to allow C implemented heap types.

  • bpo-41084: Prefix the error message with ‘f-string: ‘, when parsing an f-string expression which throws a SyntaxError.

  • bpo-40521: Empty frozensets are no longer singletons.

  • bpo-41076: Pre-feed the parser with the location of the f-string expression, not the f-string itself, which allows us to skip the shifting of the AST node locations after the parsing is completed.

  • bpo-41056: Fixes a reference to deallocated stack space during startup when constructing sys.path involving a relative symlink when code was supplied via -c. (discovered via Coverity)

  • bpo-41061: Fix incorrect expressions and asserts in hashtable code and tests.

  • bpo-41052: Opt out serialization/deserialization for _random.Random

  • bpo-40939: Rename PyPegen* functions to PyParser*, so that we can remove the old set of PyParser* functions that were using the old parser, but keep everything backwards-compatible.

  • bpo-35975: Stefan Behnel reported that cf_feature_version is used even when PyCF_ONLY_AST is not set. This is against the intention and against the documented behavior, so it’s been fixed.

  • bpo-40939: Remove the remaining files from the old parser and the symbol module.

  • bpo-40077: Convert _bz2 to use PyType_FromSpec().

  • bpo-41006: The encodings.latin_1 module is no longer imported at startup. Now it is only imported when it is the filesystem encoding or the stdio encoding.

  • bpo-40636: zip() now supports PEP 618’s strict parameter, which raises a ValueError if the arguments are exhausted at different lengths. Patch by Brandt Bucher.

  • bpo-1635741: Port _gdbm to multiphase initialization.

  • bpo-40985: Fix a bug that caused the SyntaxError text to be empty when a file ends with a line ending in a line continuation character (i.e. backslash). The error text should contain the text of the last line.

  • bpo-40958: Fix a possible buffer overflow in the PEG parser when gathering information for emitting syntax errors. Patch by Pablo Galindo.

  • bpo-1635741: Port _dbm to multiphase initialization.

  • bpo-40957: Fix refleak in _Py_fopen_obj() when PySys_Audit() fails

  • bpo-40950: Add a state to the nis module (PEP 3121) and apply the multiphase initialization. Patch by Donghee Na.

  • bpo-40947: The Python Path Configuration now takes PyConfig.platlibdir in account.

  • bpo-40939: Remove the old parser, the parser module and all associated support code, command-line options and environment variables. Patch by Pablo Galindo.

  • bpo-40847: Fix a bug where a line with only a line continuation character is not considered a blank line at tokenizer level. In such cases, more than a single NEWLINE token was emitted. The old parser was working around the issue, but the new parser threw a SyntaxError for valid input due to this. For example, an empty line following a line continuation character was interpreted as a SyntaxError.

  • bpo-40890: Each dictionary view now has a mapping attribute that provides a types.MappingProxyType wrapping the original dictionary. Patch contributed by Dennis Sweeney.

  • bpo-40889: Improved the performance of symmetric difference operations on dictionary item views. Patch by Dennis Sweeney.

  • bpo-40904: Fix possible segfault in the new PEG parser when parsing f-string containing yield statements with no value (f"{yield}"). Patch by Pablo Galindo

  • bpo-40903: Fixed a possible segfault in the new PEG parser when producing error messages for invalid assignments of the form p=p=. Patch by Pablo Galindo

  • bpo-40880: Fix invalid memory read in the new parser when checking newlines in string literals. Patch by Pablo Galindo.

  • bpo-40883: Fix memory leak in when parsing f-strings in the new parser. Patch by Pablo Galindo

  • bpo-40870: Raise ValueError when validating custom AST’s where the constants True, False and None are used within a ast.Name node.

  • bpo-40854: Allow overriding sys.platlibdir via a new PYTHONPLATLIBDIR environment variable.

  • bpo-40826: Fix GIL usage in PyOS_Readline(): lock the GIL to set an exception and pass the Python thread state when checking if there is a pending signal.

  • bpo-1635741: Port fcntl to multiphase initialization.

  • bpo-19468: Delete unnecessary instance check in importlib.reload(). Patch by Furkan Önder.

  • bpo-40824: Unexpected errors in calling the __iter__ method are no longer masked by TypeError in the in operator and functions contains(), indexOf() and countOf() of the operator module.

  • bpo-40792: Attributes start, stop and step of the range object now always has exact type int. Previously, they could have been an instance of a subclass of int.

  • bpo-40780: Fix a corner case where g-style string formatting of a float failed to remove trailing zeros.

  • bpo-38964: When there’s a SyntaxError in the expression part of an fstring, the filename attribute of the SyntaxError gets correctly set to the name of the file the fstring resides in.

  • bpo-40750: Support the “-d” debug flag in the new PEG parser. Patch by Pablo Galindo

  • bpo-40217: Instances of types created with PyType_FromSpecWithBases() will no longer automatically visit their class object when traversing references in the garbage collector. The user is expected to manually visit the object’s class. Patch by Pablo Galindo.

  • bpo-39573: Py_TYPE() is changed to the inline static function. Patch by Donghee Na.

  • bpo-40696: Fix a hang that can arise after generator.throw() due to a cycle in the exception context chain.

  • bpo-40521: Each interpreter now its has own free lists, singletons and caches:

    • Free lists: float, tuple, list, dict, frame, context, asynchronous generator, MemoryError.

    • Singletons: empty tuple, empty bytes string, empty Unicode string, single byte character, single Unicode (latin1) character.

    • Slice cache.

    They are no longer shared by all interpreters.

  • bpo-40679: Certain TypeError messages about missing or extra arguments now include the function’s qualified name. Patch by Dennis Sweeney.

  • bpo-29590: Make the stack trace correct after calling generator.throw() on a generator that has yielded from a yield from.

  • bpo-4022: Improve performance of generators by not raising internal StopIteration.

  • bpo-1635741: Port mmap to multiphase initialization.

  • bpo-1635741: Port _lzma to multiphase initialization.

  • bpo-37999: Builtin and extension functions that take integer arguments no longer accept Decimals, Fractions and other objects that can be converted to integers only with a loss (e.g. that have the __int__() method but do not have the __index__() method).

  • bpo-29882: Add int.bit_count(), counting the number of ones in the binary representation of an integer. Patch by Niklas Fiekas.

  • bpo-36982: Use ncurses extended color functions when available to support terminals with 256 colors, and add the new function curses.has_extended_color_support() to indicate whether extended color support is provided by the underlying ncurses library.

  • bpo-19569: Add the private macros _Py_COMP_DIAG_PUSH, _Py_COMP_DIAG_IGNORE_DEPR_DECLS, and _Py_COMP_DIAG_POP.

  • bpo-26680: The int type now supports the x.is_integer() method for compatibility with float.

Library

  • bpo-41900: C14N 2.0 serialisation in xml.etree.ElementTree failed for unprefixed attributes when a default namespace was defined.

  • bpo-41887: Strip leading spaces and tabs on ast.literal_eval(). Also document stripping of spaces and tabs for eval().

  • bpo-41773: Note in documentation that random.choices() doesn’t support non-finite weights, raise ValueError when given non-finite weights.

  • bpo-41840: Fix a bug in the symtable module that was causing module-scope global variables to not be reported as both local and global. Patch by Pablo Galindo.

  • bpo-41842: Add codecs.unregister() function to unregister a codec search function.

  • bpo-40564: In zipfile.Path, mutate the passed ZipFile object type instead of making a copy. Prevents issues when both the local copy and the caller’s copy attempt to close the same file handle.

  • bpo-40670: More reliable validation of statements in timeit.Timer. It now accepts “empty” statements (only whitespaces and comments) and rejects misindentent statements.

  • bpo-41833: The threading.Thread constructor now uses the target name if the target argument is specified but the name argument is omitted.

  • bpo-41817: fix tkinter.EventType Enum so all members are strings, and none are tuples

  • bpo-41810: types.EllipsisType, types.NotImplementedType and types.NoneType have been reintroduced, providing a new set of types readily interpretable by static type checkers.

  • bpo-41815: Fix SQLite3 segfault when backing up closed database. Patch contributed by Peter David McCormick.

  • bpo-41816: StrEnum added: it ensures that all members are already strings or string candidates

  • bpo-41517: fix bug allowing Enums to be extended via multiple inheritance

  • bpo-39587: use the correct mix-in data type when constructing Enums

  • bpo-41792: Add is_typeddict function to typing.py to check if a type is a TypedDict class

    Previously there was no way to check that without using private API. See the relevant issue in python/typing.

  • bpo-41789: Honor object overrides in Enum class creation (specifically, __str__, __repr__, __format__, and __reduce_ex__).

  • bpo-32218: enum.Flag and enum.IntFlag members are now iterable.

  • bpo-39651: Fix a race condition in the call_soon_threadsafe() method of asyncio.ProactorEventLoop: do nothing if the self-pipe socket has been closed.

  • bpo-1635741: Port the mashal extension module to the multi-phase initialization API (PEP 489).

  • bpo-1635741: Port the _string extension module to the multi-phase initialization API (PEP 489).

  • bpo-41732: Added an iterator to memoryview.

  • bpo-41720: Fixed turtle.Vec2D.__rmul__() for arguments which are not int or float.

  • bpo-41696: Fix handling of debug mode in asyncio.run(). This allows setting PYTHONASYNCIODEBUG or -X dev to enable asyncio debug mode when using asyncio.run().

  • bpo-41687: Fix implementation of sendfile to be compatible with Solaris.

  • bpo-41662: No longer override exceptions raised in __len__() of a sequence of parameters in sqlite3 with ProgrammingError.

  • bpo-39010: Restarting a ProactorEventLoop on Windows no longer logs spurious ConnectionResetErrors.

  • bpo-41638: ProgrammingError message for absent parameter in sqlite3 contains now the name of the parameter instead of its index when parameters are supplied as a dict.

  • bpo-41662: Fixed crash when mutate list of parameters during iteration in sqlite3.

  • bpo-41513: Improved the accuracy of math.hypot(). Internally, each step is computed with extra precision so that the result is now almost always correctly rounded.

  • bpo-41609: The pdb whatis command correctly reports instance methods as ‘Method’ rather than ‘Function’.

  • bpo-39994: Fixed pprint’s handling of dict subclasses that override __repr__.

  • bpo-32751: When cancelling the task due to a timeout, asyncio.wait_for() will now wait until the cancellation is complete also in the case when timeout is <= 0, like it does with positive timeouts.

  • bpo-37658: asyncio.wait_for() now properly handles races between cancellation of itself and the completion of the wrapped awaitable.

  • bpo-40782: Change the method asyncio.AbstractEventLoop.run_in_executor to not be a coroutine.

  • bpo-41520: Fix codeop regression that prevented turning compile warnings into errors.

  • bpo-41528: turtle uses math module functions to convert degrees to radians and vice versa and to calculate vector norm

  • bpo-41513: Minor algorithmic improvement to math.hypot() and math.dist() giving small gains in speed and accuracy.

  • bpo-41503: Fixed a race between setTarget and flush in logging.handlers.MemoryHandler.

  • bpo-41497: Fix potential UnicodeDecodeError in dis module.

  • bpo-41467: On Windows, fix asyncio recv_into() return value when the socket/pipe is closed (BrokenPipeError): return 0 rather than an empty byte string (b'').

  • bpo-41425: Make tkinter doc example runnable.

  • bpo-41421: Make an algebraic simplification to random.paretovariate(). It now is slightly less subject to round-off error and is slightly faster. Inputs that used to cause ZeroDivisionError now cause an OverflowError instead.

  • bpo-41440: Add os.cpu_count() support for VxWorks RTOS.

  • bpo-41316: Fix the tarfile module to write only basename of TAR file to GZIP compression header.

  • bpo-41384: Raise TclError instead of TypeError when an unknown option is passed to tkinter.OptionMenu.

  • bpo-41317: Use add_done_callback() in asyncio.loop.sock_accept() to unsubscribe reader early on cancellation.

  • bpo-41364: Reduce import overhead of uuid.

  • bpo-35328: Set the environment variable VIRTUAL_ENV_PROMPT at venv activation.

  • bpo-41341: Recursive evaluation of typing.ForwardRef in get_type_hints.

  • bpo-41344: Prevent creating shared_memory.SharedMemory objects with size=0.

  • bpo-41333: collections.OrderedDict.pop() is now 2 times faster.

  • bpo-41288: Unpickling invalid NEWOBJ_EX opcode with the C implementation raises now UnpicklingError instead of crashing.

  • bpo-39017: Avoid infinite loop when reading specially crafted TAR files using the tarfile module (CVE-2019-20907).

  • bpo-41273: Speed up any transport using _ProactorReadPipeTransport by calling recv_into instead of recv, thus not creating a new buffer for each recv call in the transport’s read loop.

  • bpo-41235: Fix the error handling in ssl.SSLContext.load_dh_params().

  • bpo-41207: In distutils.spawn, restore expectation that DistutilsExecError is raised when the command is not found.

  • bpo-29727: Register array.array as a MutableSequence. Patch by Pablo Galindo.

  • bpo-39168: Remove the __new__ method of typing.Generic.

  • bpo-41194: Fix a crash in the _ast module: it can no longer be loaded more than once. It now uses a global state rather than a module state.

  • bpo-41195: Add read-only ssl.SSLContext.security_level attribute to retrieve the context’s security level.

  • bpo-41193: The write_history() atexit function of the readline completer now ignores any OSError to ignore error if the filesystem is read-only, instead of only ignoring FileNotFoundError and PermissionError.

  • bpo-41182: selector: use DefaultSelector based upon implementation

  • bpo-41161: The decimal module now requires libmpdec-2.5.0. Users of –with-system-libmpdec should update their system library.

  • bpo-40874: The decimal module now requires libmpdec-2.5.0.

  • bpo-41138: Fixed the trace module CLI for Python source files with non-UTF-8 encoding.

  • bpo-31082: Use the term “iterable” in the docstring for functools.reduce().

  • bpo-40521: Remove freelist from collections.deque().

  • bpo-31938: Fix default-value signatures of several functions in the select module - by Anthony Sottile.

  • bpo-41068: Fixed reading files with non-ASCII names from ZIP archive directly after writing them.

  • bpo-41058: pdb.find_function() now correctly determines the source file encoding.

  • bpo-41056: Invalid file descriptor values are now prevented from being passed to os.fpathconf. (discovered by Coverity)

  • bpo-41056: Fix a NULL pointer dereference within the ssl module during a MemoryError in the keylog callback. (discovered by Coverity)

  • bpo-41056: Fixed an instance where a MemoryError within the zoneinfo module might not be reported or not reported at its source. (found by Coverity)

  • bpo-41048: mimetypes.read_mime_types() function reads the rule file using UTF-8 encoding, not the locale encoding. Patch by Srinivas Reddy Thatiparthy.

  • bpo-41043: Fixed the use of glob() in the stdlib: literal part of the path is now always correctly escaped.

  • bpo-41025: Fixed an issue preventing the C implementation of zoneinfo.ZoneInfo from being subclassed.

  • bpo-35018: Add the xml.sax.handler.LexicalHandler class that is present in other SAX XML implementations.

  • bpo-41002: Improve performance of HTTPResponse.read with a given amount. Patch by Bruce Merry.

  • bpo-40448: ensurepip now disables the use of pip cache when installing the bundled versions of pip and setuptools. Patch by Krzysztof Konopko.

  • bpo-40967: Removed asyncio.Task.current_task() and asyncio.Task.all_tasks(). Patch contributed by Rémi Lapeyre.

  • bpo-40924: Ensure importlib.resources.path returns an extant path for the SourceFileLoader’s resource reader. Avoids the regression identified in master while a long-term solution is devised.

  • bpo-40955: Fix a minor memory leak in subprocess module when extra_groups was specified.

  • bpo-40855: The standard deviation and variance functions in the statistics module were ignoring their mu and xbar arguments.

  • bpo-40939: Use the new PEG parser when generating the stdlib keyword module.

  • bpo-23427: Add sys.orig_argv attribute: the list of the original command line arguments passed to the Python executable.

  • bpo-33689: Ignore empty or whitespace-only lines in .pth files. This matches the documentated behavior. Before, empty lines caused the site-packages dir to appear multiple times in sys.path. By Ido Michael, contributors Malcolm Smith and Tal Einat.

  • bpo-40884: Added a defaults parameter to logging.Formatter, to allow specifying default values for custom fields. Patch by Asaf Alon and Bar Harel.

  • bpo-40876: Clarify error message in the csv module.

  • bpo-39791: Refresh importlib.metadata from importlib_metadata 1.6.1.

  • bpo-40807: Stop codeop._maybe_compile, used by code.InteractiveInterpreter (and IDLE). from emitting each warning three times.

  • bpo-32604: Fix reference leak in the select module when the module is imported in a subinterpreter.

  • bpo-39791: Built-in loaders (SourceFileLoader and ZipImporter) now supply TraversableResources implementations for ResourceReader, and the fallback function has been removed.

  • bpo-39314: rlcompleter.Completer and the standard Python shell now close the parenthesis for functions that take no arguments. Patch contributed by Rémi Lapeyre.

  • bpo-17005: The topological sort functionality that was introduced initially in the functools module has been moved to a new graphlib module to better accommodate the new tools and keep the original scope of the functools module. Patch by Pablo Galindo

  • bpo-40834: Fix truncate when sending str object with_xxsubinterpreters.channel_send.

  • bpo-40755: Add rich comparisons to collections.Counter().

  • bpo-26407: Unexpected errors in calling the __iter__ method are no longer masked by TypeError in csv.reader(), csv.writer.writerow() and csv.writer.writerows().

  • bpo-39384: Fixed email.contentmanager to allow set_content() to set a null string.

  • bpo-40744: The sqlite3 module uses SQLite API functions that require SQLite v3.7.3 or higher. This patch removes support for older SQLite versions, and explicitly requires SQLite 3.7.3 both at build, compile and runtime. Patch by Sergey Fedoseev and Erlend E. Aasland.

  • bpo-40777: Initialize PyDateTime_IsoCalendarDateType.tp_base at run-time to avoid errors on some compilers.

  • bpo-38488: Update ensurepip to install pip 20.1.1 and setuptools 47.1.0.

  • bpo-40792: The result of operator.index() now always has exact type int. Previously, the result could have been an instance of a subclass of int.

  • bpo-40767: webbrowser now properly finds the default browser in pure Wayland systems by checking the WAYLAND_DISPLAY environment variable. Patch contributed by Jérémy Attali.

  • bpo-40791: hashlib.compare_digest() uses OpenSSL’s CRYPTO_memcmp() function when OpenSSL is available.

  • bpo-40795: ctypes module: If ctypes fails to convert the result of a callback or if a ctypes callback function raises an exception, sys.unraisablehook is now called with an exception set. Previously, the error was logged into stderr by PyErr_Print().

  • bpo-16995: Add base64.b32hexencode() and base64.b32hexdecode() to support the Base32 Encoding with Extended Hex Alphabet.

  • bpo-30008: Fix ssl code to be compatible with OpenSSL 1.1.x builds that use no-deprecated and --api=1.1.0.

  • bpo-30064: Fix asyncio loop.sock_* race condition issue

  • bpo-40759: Deprecate the symbol module.

  • bpo-40756: The second argument (extra) of LoggerAdapter.__init__ now defaults to None.

  • bpo-37129: Add a new os.RWF_APPEND flag for os.pwritev().

  • bpo-40737: Fix possible reference leak for sqlite3 initialization.

  • bpo-40726: Handle cases where the end_lineno is None on ast.increment_lineno().

  • bpo-40698: distutils upload creates SHA2-256 and Blake2b-256 digests. MD5 digests is skipped if platform blocks MD5.

  • bpo-40695: hashlib no longer falls back to builtin hash implementations when OpenSSL provides a hash digest and the algorithm is blocked by security policy.

  • bpo-9216: hashlib.new() passed usedforsecurity to OpenSSL EVP constructor _hashlib.new(). test_hashlib and test_smtplib handle strict security policy better.

  • bpo-40614: ast.parse() will not parse self documenting expressions in f-strings when passed feature_version is less than (3, 8).

  • bpo-40626: Add h5 file extension as MIME Type application/x-hdf5, as per HDF Group recommendation for HDF5 formatted data files. Patch contributed by Mark Schwab.

  • bpo-25920: On macOS, when building Python for macOS 10.4 and older, which wasn’t the case for python.org macOS installer, socket.getaddrinfo() no longer uses an internal lock to prevent race conditions when calling getaddrinfo() which is thread-safe since macOS 10.5. Python 3.9 requires macOS 10.6 or newer. The internal lock caused random hang on fork when another thread was calling socket.getaddrinfo(). The lock was also used on FreeBSD older than 5.3, OpenBSD older than 201311 and NetBSD older than 4.

  • bpo-40671: Prepare _hashlib for PEP 489 and use PyModule_AddType().

  • bpo-32309: Added a new coroutine asyncio.to_thread(). It is mainly used for running IO-bound functions in a separate thread to avoid blocking the event loop, and essentially works as a high-level version of run_in_executor() that can directly take keyword arguments.

  • bpo-36543: Restored the deprecated xml.etree.cElementTree module.

  • bpo-40611: MAP_POPULATE constant has now been added to the list of exported mmap module flags.

  • bpo-39881: PEP 554 for use in the test suite. (Patch By Joannah Nanjekye)

  • bpo-13097: ctypes now raises an ArgumentError when a callback is invoked with more than 1024 arguments.

  • bpo-39385: A new test assertion context-manager, unittest.assertNoLogs() will ensure a given block of code emits no log messages using the logging module. Contributed by Kit Yan Choi.

  • bpo-23082: Updated the error message and docs of PurePath.relative_to() to better reflect the function behaviour.

  • bpo-40318: Use SQLite3 trace v2 API, if it is available.

  • bpo-40105: ZipFile truncates files to avoid corruption when a shorter comment is provided in append (“a”) mode. Patch by Jan Mazur.

  • bpo-40084: Fix Enum.__dir__: dir(Enum.member) now includes attributes as well as methods.

  • bpo-31122: ssl.wrap_socket() now raises ssl.SSLEOFError rather than OSError when peer closes connection during TLS negotiation

  • bpo-39728: fix default _missing_ so a duplicate ValueError is not set as the __context__ of the original ValueError.

  • bpo-39244: Fixed multiprocessing.context.get_all_start_methods to properly return the default method first on macOS.

  • bpo-39040: Fix parsing of invalid mime headers parameters by collapsing whitespace between encoded words in a bare-quote-string.

  • bpo-38731: Add --quiet option to command-line interface of py_compile. Patch by Gregory Schevchenko.

  • bpo-35714: struct.error is now raised if there is a null character in a struct format string.

  • bpo-38144: Added the root_dir and dir_fd parameters in glob.glob().

  • bpo-26543: Fix IMAP4.noop() when debug mode is enabled (ex: imaplib.Debug = 3).

  • bpo-12178: csv.writer() now correctly escapes escapechar when input contains escapechar. Patch by Catalin Iacob, Berker Peksag, and Itay Elbirt.

  • bpo-36290: AST nodes are now raising TypeError on conflicting keyword arguments. Patch contributed by Rémi Lapeyre.

  • bpo-33944: Added site.py site-packages tracing in verbose mode.

  • bpo-35078: Refactor formatweekday, formatmonthname methods in LocaleHTMLCalendar and LocaleTextCalendar classes in calendar module to call the base class methods.This enables customizable CSS classes for LocaleHTMLCalendar. Patch by Srinivas Reddy Thatiparthy

  • bpo-29620: assertWarns() no longer raises a RuntimeException when accessing a module’s __warningregistry__ causes importation of a new module, or when a new module is imported in another thread. Patch by Kernc.

  • bpo-31844: Remove ParserBase.error() method from the private and undocumented _markupbase module. html.parser.HTMLParser is the only subclass of ParserBase and its error() implementation was deprecated in Python 3.4 and removed in Python 3.5.

  • bpo-34226: Fix cgi.parse_multipart without content_length. Patch by Roger Duran

  • bpo-33660: Fix pathlib.PosixPath to resolve a relative path located on the root directory properly.

  • bpo-28557: Improve the error message for a misbehaving rawio.readinto

  • bpo-26680: The d.is_integer() method is added to the Decimal type, for compatibility with other number types.

  • bpo-26680: The x.is_integer() method is incorporated into the abstract types of the numeric tower, Real, Rational and Integral, with appropriate default implementations.

Documentation

  • bpo-41428: Add documentation for PEP 604 (Allow writing union types as X | Y).

  • bpo-41774: In Programming FAQ “Sequences (Tuples/Lists)” section, add “How do you remove multiple items from a list”.

  • bpo-35293: Fix RemovedInSphinx40Warning when building the documentation. Patch by Donghee Na.

  • bpo-37149: Change Shipman tkinter doc link from archive.org to TkDocs. (The doc has been removed from the NMT server.) The new link responds much faster and includes a short explanatory note.

  • bpo-41726: Update the refcounts info of PyType_FromModuleAndSpec.

  • bpo-41624: Fix the signature of typing.Coroutine.

  • bpo-40204: Enable Sphinx 3.2 c_allow_pre_v3 option and disable c_warn_on_allowed_pre_v3 option to make the documentation compatible with Sphinx 2 and Sphinx 3.

  • bpo-41045: Add documentation for debug feature of f-strings.

  • bpo-41314: Changed the release when from __future__ import annotations becomes the default from 4.0 to 3.10 (following a change in PEP 563).

  • bpo-40979: Refactored typing.rst, arranging more than 70 classes, functions, and decorators into new sub-sections.

  • bpo-40552: Fix in tutorial section 4.2. Code snippet is now correct.

  • bpo-39883: Make code, examples, and recipes in the Python documentation be licensed under the more permissive BSD0 license in addition to the existing Python 2.0 license.

  • bpo-37703: Updated Documentation to comprehensively elaborate on the behaviour of gather.cancel()

Tests

  • bpo-41939: Fix test_site.test_license_exists_at_url(): call urllib.request.urlcleanup() to reset the global urllib.request._opener. Patch by Victor Stinner.

  • bpo-41731: Make test_cmd_line_script pass with option ‘-vv’.

  • bpo-41602: Add tests for SIGINT handling in the runpy module.

  • bpo-41521: test.support: Rename blacklist parameter of check__all__() to not_exported.

  • bpo-41477: Make ctypes optional in test_genericalias.

  • bpo-41085: Fix integer overflow in the array.array.index() method on 64-bit Windows for index larger than 2**31.

  • bpo-41069: test.support.TESTFN and the current directory for tests when run via test.regrtest contain now non-ascii characters if possible.

  • bpo-38377: On Linux, skip tests using multiprocessing if the current user cannot create a file in /dev/shm/ directory. Add the skip_if_broken_multiprocessing_synchronize() function to the test.support module.

  • bpo-41009: Fix use of support.require_{linux|mac|freebsd}_version() decorators as class decorator.

  • bpo-41003: Fix test_copyreg when numpy is installed: test.pickletester now saves/restores warnings filters when importing numpy, to ignore filters installed by numpy.

  • bpo-40964: Disable remote imaplib tests, host cyrus.andrew.cmu.edu is blocking incoming connections.

  • bpo-40927: Fix test_binhex when run twice: it now uses import_fresh_module() to ensure that it raises DeprecationWarning each time.

  • bpo-17258: Skip some multiprocessing tests when MD5 hash digest is blocked.

  • bpo-31904: Increase LOOPBACK_TIMEOUT to 10 for VxWorks RTOS.

  • bpo-38169: Increase code coverage for SharedMemory and ShareableList

  • bpo-34401: Make test_gdb properly run on HP-UX. Patch by Michael Osipov.

Build

  • bpo-38249: Update Py_UNREACHABLE to use __builtin_unreachable() if only the compiler is able to use it. Patch by Donghee Na.

  • bpo-41617: Fix pycore_bitutils.h header file to support old clang versions: __builtin_bswap16() is not available in LLVM clang 3.0.

  • bpo-40204: Pin Sphinx version to 2.3.1 in Doc/Makefile.

  • bpo-36020: The C99 functions snprintf() and vsnprintf() are now required to build Python.

  • bpo-40684: make install now uses the PLATLIBDIR variable for the destination lib-dynload/ directory when ./configure --with-platlibdir is used.

  • bpo-40683: Fixed an issue where the zoneinfo module and its tests were not included when Python is installed with make.

Windows

  • bpo-41744: Fixes automatic import of props file when using the Nuget package.

  • bpo-41627: The user site directory for 32-bit now includes a -32 suffix to distinguish it from the 64-bit interpreter’s directory.

  • bpo-41526: Fixed layout of final page of the installer by removing the special thanks to Mark Hammond (with his permission).

  • bpo-41492: Fixes the description that appears in UAC prompts.

  • bpo-40948: Improve post-install message to direct people to the “py” command.

  • bpo-41412: The installer will now fail to install on Windows 7 and Windows 8. Further, the UCRT dependency is now always downloaded on demand.

  • bpo-40741: Update Windows release to include SQLite 3.32.3.

  • bpo-41142: msilib now supports creating CAB files with non-ASCII file path and adding files with non-ASCII file path to them.

  • bpo-41074: Fixed support of non-ASCII names in functions msilib.OpenDatabase() and msilib.init_database() and non-ASCII SQL in method msilib.Database.OpenView().

  • bpo-41039: Stable ABI redirection DLL (python3.dll) now uses #pragma comment(linker) for re-exporting.

  • bpo-40164: Updates Windows OpenSSL to 1.1.1g

  • bpo-39631: Changes the registered MIME type for .py files on Windows to text/x-python instead of text/plain.

  • bpo-40677: Manually define IO_REPARSE_TAG_APPEXECLINK in case some old Windows SDK doesn’t have it.

  • bpo-37556: Extend py.exe help to mention overrides via venv, shebang, environmental variables & ini files.

macOS

  • bpo-41557: Update macOS installer to use SQLite 3.33.0.

  • bpo-39580: Avoid opening Finder window if running installer from the command line. Patch contributed by Rick Heil.

  • bpo-41100: Fix configure error when building on macOS 11. Note that the current Python release was released shortly after the first developer preview of macOS 11 (Big Sur); there are other known issues with building and running on the developer preview. Big Sur is expected to be fully supported in a future bugfix release of Python 3.8.x and with 3.9.0.

  • bpo-40741: Update macOS installer to use SQLite 3.32.3.

  • bpo-41005: fixed an XDG settings issue not allowing macos to open browser in webbrowser.py

  • bpo-40741: Update macOS installer to use SQLite 3.32.2.

IDLE

  • bpo-41775: Use ‘IDLE Shell’ as shell title

  • bpo-35764: Rewrite the Calltips doc section.

  • bpo-40181: In calltips, stop reminding that ‘/’ marks the end of positional-only arguments.

  • bpo-41468: Improve IDLE run crash error message (which users should never see).

  • bpo-41373: Save files loaded with no line ending, as when blank, or different line endings, by setting its line ending to the system default. Fix regression in 3.8.4 and 3.9.0b4.

  • bpo-41300: Save files with non-ascii chars. Fix regression released in 3.9.0b4 and 3.8.4.

  • bpo-37765: Add keywords to module name completion list. Rewrite Completions section of IDLE doc.

  • bpo-41152: The encoding of stdin, stdout and stderr in IDLE is now always UTF-8.

  • bpo-41144: Make Open Module open a special module such as os.path.

  • bpo-39885: Make context menu Cut and Copy work again when right-clicking within a selection.

  • bpo-40723: Make test_idle pass when run after import.

C API

  • bpo-41936: Removed undocumented macros Py_ALLOW_RECURSION and Py_END_ALLOW_RECURSION and the recursion_critical field of the PyInterpreterState structure.

  • bpo-41692: The PyUnicode_InternImmortal() function is now deprecated and will be removed in Python 3.12: use PyUnicode_InternInPlace() instead. Patch by Victor Stinner.

  • bpo-41842: Add PyCodec_Unregister() function to unregister a codec search function.

  • bpo-41834: Remove the _Py_CheckRecursionLimit variable: it has been replaced by ceval.recursion_limit of the PyInterpreterState structure. Patch by Victor Stinner.

  • bpo-41689: Types created with PyType_FromSpec() now make any signature in their tp_doc slot accessible from __text_signature__.

  • bpo-41524: Fix bug in PyOS_mystrnicmp and PyOS_mystricmp that incremented pointers beyond the end of a string.

  • bpo-41324: Add a minimal decimal capsule API. The API supports fast conversions between Decimals up to 38 digits and their triple representation as a C struct.

  • bpo-30155: Add PyDateTime_DATE_GET_TZINFO() and PyDateTime_TIME_GET_TZINFO() macros for accessing the tzinfo attributes of datetime.datetime and datetime.time objects.

  • bpo-40170: Revert PyType_HasFeature() change: it reads again directly the PyTypeObject.tp_flags member when the limited C API is not used, rather than always calling PyType_GetFlags() which hides implementation details.

  • bpo-41123: Remove PyUnicode_AsUnicodeCopy.

  • bpo-41123: Removed PyLong_FromUnicode().

  • bpo-41123: Removed PyUnicode_GetMax().

  • bpo-41123: Removed Py_UNICODE_str* functions manipulating Py_UNICODE* strings.

  • bpo-41103: PyObject_AsCharBuffer(), PyObject_AsReadBuffer(), PyObject_CheckReadBuffer(), and PyObject_AsWriteBuffer() are removed. Please migrate to new buffer protocol; PyObject_GetBuffer() and PyBuffer_Release().

  • bpo-36346: Raises DeprecationWarning for PyUnicode_FromUnicode(NULL, size) and PyUnicode_FromStringAndSize(NULL, size) with size > 0.

  • bpo-36346: Mark Py_UNICODE_COPY, Py_UNICODE_FILL, PyUnicode_WSTR_LENGTH, PyUnicode_FromUnicode, PyUnicode_AsUnicode, and PyUnicode_AsUnicodeAndSize as deprecated in C. Remove Py_UNICODE_MATCH which was deprecated and broken since Python 3.3.

  • bpo-40989: The PyObject_INIT() and PyObject_INIT_VAR() macros become aliases to, respectively, PyObject_Init() and PyObject_InitVar() functions.

  • bpo-36020: On Windows, #include "pyerrors.h" no longer defines snprintf and vsnprintf macros.

  • bpo-40943: The PY_SSIZE_T_CLEAN macro must now be defined to use PyArg_ParseTuple() and Py_BuildValue() formats which use #: es#, et#, s#, u#, y#, z#, U# and Z#. See Parsing arguments and building values and the PEP 353.

  • bpo-40910: Export explicitly the Py_GetArgcArgv() function to the C API and document the function. Previously, it was exported implicitly which no longer works since Python is built with -fvisibility=hidden.

  • bpo-40724: Allow defining buffer slots in type specs.

  • bpo-40679: Fix a _PyEval_EvalCode() crash if qualname argument is NULL.

  • bpo-40839: Calling PyDict_GetItem() without GIL held had been allowed for historical reason. It is no longer allowed.

  • bpo-40826: PyOS_InterruptOccurred() now fails with a fatal error if it is called with the GIL released.

  • bpo-40792: The result of PyNumber_Index() now always has exact type int. Previously, the result could have been an instance of a subclass of int.

  • bpo-39573: Convert Py_REFCNT() and Py_SIZE() macros to static inline functions. They cannot be used as l-value anymore: use Py_SET_REFCNT() and Py_SET_SIZE() to set an object reference count and size. This change is backward incompatible on purpose, to prepare the C API for an opaque PyObject structure.

  • bpo-40703: The PyType_FromSpec*() functions no longer overwrite the type’s “__module__” attribute if it is set via “Py_tp_members” or “Py_tp_getset”.

  • bpo-39583: Remove superfluous “extern C” declarations from Include/cpython/*.h.

Python 3.9.0 beta 1

Release date: 2020-05-19

Security

Core and Builtins

  • bpo-40663: Correctly generate annotations where parentheses are omitted but required (e.g: Type[(str, int, *other))].

  • bpo-40596: Fixed str.isidentifier() for non-canonicalized strings containing non-BMP characters on Windows.

  • bpo-40593: Improved syntax errors for invalid characters in source code.

  • bpo-40585: Fixed a bug when using codeop.compile_command() that was causing exceptions to be swallowed with the new parser. Patch by Pablo Galindo

  • bpo-40566: Apply PEP 573 to abc.

  • bpo-40502: Initialize n->n_col_offset. (Patch by Joannah Nanjekye)

  • bpo-40527: Fix command line argument parsing: no longer write errors multiple times into stderr.

  • bpo-1635741: Port errno to multiphase initialization (PEP 489).

  • bpo-40523: Add pass-throughs for hash() and reversed() to weakref.proxy objects. Patch by Pablo Galindo.

  • bpo-1635741: Port syslog to multiphase initialization (PEP 489).

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

  • bpo-40417: Fix imp module deprecation warning when PyImport_ReloadModule is called. Patch by Robert Rouhani.

  • bpo-40408: Fixed support of nested type variables in GenericAlias (e.g. list[list[T]]).

  • bpo-1635741: Port _stat module to multiphase initialization (PEP 489).

  • bpo-29587: Enable implicit exception chaining when calling generator.throw().

  • bpo-40328: Add tools for generating mappings headers for CJKCodecs.

  • bpo-40228: Setting frame.f_lineno is now robust w.r.t. changes in the source-to-bytecode compiler

  • bpo-38880: Added the ability to list interpreters associated with channel ends in the internal subinterpreters module.

  • bpo-37986: Improve performance of PyLong_FromDouble() for values that fit into long.

Library

  • bpo-40662: Fixed ast.get_source_segment() for ast nodes that have incomplete location information. Patch by Irit Katriel.

  • bpo-40665: Convert bisect to use Argument Clinic.

  • bpo-40536: Added the available_timezones() function to the zoneinfo module. Patch by Paul Ganssle.

  • bpo-40645: The hmac.HMAC exposes internal implementation details. The attributes digest_cons, inner, and outer are deprecated and will be removed in the future.

  • bpo-40645: The internal module _hashlib wraps and exposes OpenSSL’s HMAC API. The new code will be used in Python 3.10 after the internal implementation details of the pure Python HMAC module are no longer part of the public API.

  • bpo-40637: Builtin hash modules can now be disabled or selectively enabled with configure --with-builtin-hashlib-hashes=sha3,blake1 or --without-builtin-hashlib-hashes.

  • bpo-37630: The hashlib module can now use SHA3 hashes and SHAKE XOF from OpenSSL when available.

  • bpo-40479: The hashlib now compiles with OpenSSL 3.0.0-alpha2.

  • bpo-40257: Revert changes to inspect.getdoc().

  • bpo-40607: When cancelling a task due to timeout, asyncio.wait_for() will now propagate the exception if an error happens during cancellation. Patch by Roman Skurikhin.

  • bpo-40612: Fix edge cases in SyntaxError formatting. If the offset is <= 0, no caret is printed. If the offset is > line length, the caret is printed pointing just after the last character.

  • bpo-40597: If text content lines are longer than policy.max_line_length, always use a content-encoding to make sure they are wrapped.

  • bpo-40571: Added functools.cache() as a simpler, more discoverable way to access the unbounded cache variant of lru_cache(maxsize=None).

  • bpo-40503: PEP 615, the zoneinfo module. Adds support for the IANA time zone database.

  • bpo-40397: Removed attributes __args__ and __parameters__ from special generic aliases like typing.List (not subscripted).

  • bpo-40549: Convert posixmodule.c (“posix” or “nt” module) to the multiphase initialization (PEP 489).

  • bpo-31033: Add a msg argument to Future.cancel() and Task.cancel().

  • bpo-40541: Added an optional counts parameter to random.sample().

  • bpo-40515: The ssl and hashlib modules now actively check that OpenSSL is build with thread support. Python 3.7.0 made thread support mandatory and no longer works safely with a no-thread builds.

  • bpo-31033: When a asyncio.Task is cancelled, the exception traceback now chains all the way back to where the task was first interrupted.

  • bpo-40504: functools.lru_cache() objects can now be the targets of weakrefs.

  • bpo-40559: Fix possible memory leak in the C implementation of asyncio.Task.

  • bpo-40480: fnmatch.fnmatch() could take exponential time in the presence of multiple * pattern characters. This was repaired by generating more elaborate regular expressions to avoid futile backtracking.

  • bpo-40495: compileall is now able to use hardlinks to prevent duplicates in a case when .pyc files for different optimization levels have the same content.

  • bpo-40457: The ssl module now support OpenSSL builds without TLS 1.0 and 1.1 methods.

  • bpo-40355: Improve error reporting in ast.literal_eval() in the presence of malformed ast.Dict nodes instead of silently ignoring any non-conforming elements. Patch by Curtis Bucher.

  • bpo-40465: Deprecated the optional random argument to random.shuffle().

  • bpo-40459: platform.win32_ver() now produces correct ptype strings instead of empty strings.

  • bpo-39435: The first argument of pickle.loads() is now positional-only.

  • bpo-39305: Update nntplib to merge nntplib.NNTP and nntplib._NNTPBase. Patch by Donghee Na.

  • bpo-32494: Update dbm.gnu to use gdbm_count if possible when calling len(). Patch by Donghee Na.

  • bpo-40453: Add isolated=True keyword-only parameter to _xxsubinterpreters.create(). An isolated subinterpreter cannot spawn threads, spawn a child process or call os.fork().

  • bpo-40286: Remove _random.Random.randbytes(): the C implementation of randbytes(). Implement the method in Python to ease subclassing: randbytes() now directly reuses getrandbits().

  • bpo-40394: Added default arguments to difflib.SequenceMatcher.find_longest_match().

  • bpo-39995: Fix a race condition in concurrent.futures._ThreadWakeup: access to _ThreadWakeup is now protected with the shutdown lock.

  • bpo-30966: Process.shutdown(wait=True) of concurrent.futures now closes explicitly the result queue.

  • bpo-30966: Add a new close() method to the SimpleQueue class to explicitly close the queue.

  • bpo-39966: Revert bpo-25597. unittest.mock.MagicMock with wraps’ set uses default return values for magic methods.

  • bpo-39791: Added files() function to importlib.resources with support for subdirectories in package data, matching backport in importlib_resources 1.5.

  • bpo-40375: imaplib.IMAP4.unselect() is added. Patch by Donghee Na.

  • bpo-40389: repr() now returns typing.Optional[T] when called for typing.Union of two types, one of which is NoneType.

  • bpo-40291: Add support for CAN_J1939 sockets (available on Linux 5.4+)

  • bpo-40273: types.MappingProxyType is now reversible.

  • bpo-39075: The repr for types.SimpleNamespace is now insertion ordered rather than alphabetical.

  • bpo-40192: On AIX, thread_time() is now implemented with thread_cputime() which has nanosecond resolution, rather than clock_gettime(CLOCK_THREAD_CPUTIME_ID) which has a resolution of 10 milliseconds. Patch by Batuhan Taskaya.

  • bpo-40025: Raise TypeError when _generate_next_value_ is defined after members. Patch by Ethan Onstott.

  • bpo-39058: In the argparse module, the repr for Namespace() and other argument holders now displayed in the order attributes were added. Formerly, it displayed in alphabetical order even though argument order is preserved the user visible parts of the module.

  • bpo-24416: The isocalendar() methods of datetime.date and datetime.datetime now return a named tuple instead of a tuple.

Documentation

  • bpo-34790: Add version of removal for explicit passing of coros to asyncio.wait()’s documentation

  • bpo-40561: Provide docstrings for webbrowser open functions.

  • bpo-40499: Mention that asyncio.wait() requires a non-empty set of awaitables.

  • bpo-39705: Tutorial example for sorted() in the Loop Techniques section is given a better explanation. Also a new example is included to explain sorted()’s basic behavior.

  • bpo-39435: Fix an incorrect signature for pickle.loads() in the docs

Tests

  • bpo-40055: distutils.tests now saves/restores warnings filters to leave them unchanged. Importing tests imports docutils which imports pkg_resources which adds a warnings filter.

  • bpo-40436: test_gdb and test.pythoninfo now check gdb command exit code.

Build

  • bpo-40653: Move _dirnameW out of HAVE_SYMLINK to fix a potential compiling issue.

  • bpo-40514: Add --with-experimental-isolated-subinterpreters build option to configure: better isolate subinterpreters, experimental build mode.

Windows

  • bpo-40650: Include winsock2.h in pytime.c for timeval.

  • bpo-40458: Increase reserved stack space to prevent overflow crash on Windows.

  • bpo-39148: Add IPv6 support to asyncio datagram endpoints in ProactorEventLoop. Change the raised exception for unknown address families to ValueError as it’s not coming from Windows API.

macOS

  • bpo-34956: When building Python on macOS from source, _tkinter now links with non-system Tcl and Tk frameworks if they are installed in /Library/Frameworks, as had been the case on older releases of macOS. If a macOS SDK is explicitly configured, by using --enable-universalsdk= or -isysroot, only the SDK itself is searched. The default behavior can still be overridden with --with-tcltk-includes and --with-tcltk-libs.

  • bpo-35569: Expose RFC 3542 IPv6 socket options.

Tools/Demos

  • bpo-40479: Update multissltest helper to test with latest OpenSSL 1.0.2, 1.1.0, 1.1.1, and 3.0.0-alpha.

  • bpo-40431: Fix a syntax typo in turtledemo that now raises a SyntaxError.

  • bpo-40163: Fix multissltest tool. OpenSSL has changed download URL for old releases. The multissltest tool now tries to download from current and old download URLs.

C API

  • bpo-39465: Remove the _PyUnicode_ClearStaticStrings() function from the C API.

  • bpo-38787: Add PyCFunction_CheckExact() macro for exact type checks now that we allow subtypes of PyCFunction, as well as PyCMethod_CheckExact() and PyCMethod_Check() for the new PyCMethod subtype.

  • bpo-40545: Declare _PyErr_GetTopmostException() with PyAPI_FUNC() to properly export the function in the C API. The function remains private (_Py) prefix.

  • bpo-40412: Nullify inittab_copy during finalization, preventing future interpreter initializations in an embedded situation from crashing. Patch by Gregory Szorc.

  • bpo-40429: The PyThreadState_GetFrame() function now returns a strong reference to the frame.

  • bpo-40428: Remove the following functions from the C API. Call PyGC_Collect() explicitly to free all free lists.

    • PyAsyncGen_ClearFreeLists()

    • PyContext_ClearFreeList()

    • PyDict_ClearFreeList()

    • PyFloat_ClearFreeList()

    • PyFrame_ClearFreeList()

    • PyList_ClearFreeList()

    • PySet_ClearFreeList()

    • PyTuple_ClearFreeList()

  • bpo-40421: New PyFrame_GetBack() function: get the frame next outer frame.

  • bpo-40421: New PyFrame_GetCode() function: return a borrowed reference to the frame code.

  • bpo-40217: Ensure that instances of types created with PyType_FromSpecWithBases() will visit its class object when traversing references in the garbage collector (implemented as an extension of the provided tp_traverse). Patch by Pablo Galindo.

  • bpo-38787: Module C state is now accessible from C-defined heap type methods (PEP 573). Patch by Marcel Plch and Petr Viktorin.

Python 3.9.0 alpha 6

Release date: 2020-04-27

Security

  • bpo-40121: Fixes audit events raised on creating a new socket.

  • bpo-39073: Disallow CR or LF in email.headerregistry.Address arguments to guard against header injection attacks.

  • bpo-39503: CVE-2020-8492: The AbstractBasicAuthHandler class of the urllib.request module uses an inefficient regular expression which can be exploited by an attacker to cause a denial of service. Fix the regex to prevent the catastrophic backtracking. Vulnerability reported by Ben Caller and Matt Schwager.

Core and Builtins

  • bpo-40313: Improve the performance of bytes.hex().

  • bpo-40334: Switch to a new parser, based on PEG. For more details see PEP 617. To temporarily switch back to the old parser, use -X oldparser or PYTHONOLDPARSER=1. In Python 3.10 we will remove the old parser completely, including the parser module (already deprecated) and anything that depends on it.

  • bpo-40267: Fix the tokenizer to display the correct error message, when there is a SyntaxError on the last input character and no newline follows. It used to be unexpected EOF while parsing, while it should be invalid syntax.

  • bpo-39522: Correctly unparse explicit u prefix for strings when postponed evaluation for annotations activated. Patch by Batuhan Taskaya.

  • bpo-40246: Report a specialized error message, invalid string prefix, when the tokenizer encounters a string with an invalid prefix.

  • bpo-40082: Fix the signal handler: it now always uses the main interpreter, rather than trying to get the current Python thread state.

  • bpo-37388: str.encode() and str.decode() no longer check the encoding and errors in development mode or in debug mode during Python finalization. The codecs machinery can no longer work on very late calls to str.encode() and str.decode().

  • bpo-40077: Fix possible refleaks in _json, memo of PyScannerObject should be traversed.

  • bpo-37207: Speed up calls to dict() by using the PEP 590 vectorcall calling convention.

  • bpo-40141: Add column and line information to ast.keyword nodes. Patch by Pablo Galindo.

  • bpo-1635741: Port resource to multiphase initialization (PEP 489).

  • bpo-1635741: Port math to multiphase initialization (PEP 489).

  • bpo-1635741: Port _uuid module to multiphase initialization (PEP 489).

  • bpo-40077: Convert json module to use PyType_FromSpec().

  • bpo-40067: Improve the error message for multiple star expressions in an assignment. Patch by Furkan Onder

  • bpo-1635741: Port _functools module to multiphase initialization (PEP 489). Patch by Paulo Henrique Silva.

  • bpo-1635741: Port operator module to multiphase initialization (PEP 489). Patch by Paulo Henrique Silva.

  • bpo-20526: Fix PyThreadState_Clear(). PyThreadState.frame is a borrowed reference, not a strong reference: PyThreadState_Clear() must not call Py_CLEAR(tstate->frame).

  • bpo-1635741: Port time module to multiphase initialization (PEP 489). Patch by Paulo Henrique Silva.

  • bpo-1635741: Port _weakref extension module to multiphase initialization (PEP 489).

  • bpo-40020: Fix a leak and subsequent crash in parsetok.c caused by realloc misuse on a rare codepath.

  • bpo-39939: Added str.removeprefix and str.removesuffix methods and corresponding bytes, bytearray, and collections.UserString methods to remove affixes from a string if present. See PEP 616 for a full description. Patch by Dennis Sweeney.

  • bpo-39481: Implement PEP 585. This supports list[int], tuple[str, …] etc.

  • bpo-32894: Support unparsing of infinity numbers in postponed annotations. Patch by Batuhan Taşkaya.

  • bpo-37207: Speed up calls to list() by using the PEP 590 vectorcall calling convention. Patch by Mark Shannon.

Library

  • bpo-40398: typing.get_args() now always returns an empty tuple for special generic aliases.

  • bpo-40396: Functions typing.get_origin(), typing.get_args() and typing.get_type_hints() support now generic aliases like list[int].

  • bpo-38061: Optimize the subprocess module on FreeBSD using closefrom(). A single close(fd) syscall is cheap, but when sysconf(_SC_OPEN_MAX) is high, the loop calling close(fd) on each file descriptor can take several milliseconds.

    The workaround on FreeBSD to improve performance was to load and mount the fdescfs kernel module, but this is not enabled by default.

    Initial patch by Ed Maste (emaste), Conrad Meyer (cem), Kyle Evans (kevans) and Kubilay Kocak (koobs): https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

  • bpo-38061: On FreeBSD, os.closerange(fd_low, fd_high) now calls closefrom(fd_low) if fd_high is greater than or equal to sysconf(_SC_OPEN_MAX).

    Initial patch by Ed Maste (emaste), Conrad Meyer (cem), Kyle Evans (kevans) and Kubilay Kocak (koobs): https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

  • bpo-40360: The lib2to3 module is pending deprecation due to PEP 617.

  • bpo-40138: Fix the Windows implementation of os.waitpid() for exit code larger than INT_MAX >> 8. The exit status is now interpreted as an unsigned number.

  • bpo-39942: Set “__main__” as the default module name when “__name__” is missing in typing.TypeVar. Patch by Weipeng Hong.

  • bpo-40275: The logging package is now imported lazily in unittest only when the assertLogs() assertion is used.

  • bpo-40275: The asyncio package is now imported lazily in unittest only when the IsolatedAsyncioTestCase class is used.

  • bpo-40330: In ShareableList.__setitem__(), check the size of a new string item after encoding it to utf-8, not before.

  • bpo-40148: Added pathlib.Path.with_stem() to create a new Path with the stem replaced.

  • bpo-40325: Deprecated support for set objects in random.sample().

  • bpo-40257: Improved help for the typing module. Docstrings are now shown for all special forms and special generic aliases (like Union and List). Using help() with generic alias like List[int] will show the help for the correspondent concrete type (list in this case).

  • bpo-40257: inspect.getdoc() no longer returns docstring inherited from the type of the object or from parent class if it is a class if it is not defined in the object itself. In pydoc the documentation string is now shown not only for class, function, method etc, but for any object that has its own __doc__ attribute.

  • bpo-40287: Fixed SpooledTemporaryFile.seek() to return the position.

  • bpo-40290: Added zscore() to statistics.NormalDist().

  • bpo-40282: Allow random.getrandbits(0) to succeed and to return 0.

  • bpo-40286: Add random.randbytes() function and random.Random.randbytes() method to generate random bytes.

  • bpo-40277: collections.namedtuple() now provides a human-readable repr for its field accessors.

  • bpo-40270: The included copy of sqlite3 on Windows is now compiled with the json extension. This allows the use of functions such as json_object.

  • bpo-29255: Wait in KqueueSelector.select when no fds are registered

  • bpo-40260: Ensure modulefinder uses io.open_code() and respects coding comments.

  • bpo-40234: Allow again to spawn daemon threads in subinterpreters (revert change which denied them).

  • bpo-39207: Workers in ProcessPoolExecutor are now spawned on demand, only when there are no available idle workers to reuse. This optimizes startup overhead and reduces the amount of lost CPU time to idle workers. Patch by Kyle Stanley.

  • bpo-40091: Fix a hang at fork in the logging module: the new private _at_fork_reinit() method is now used to reinitialize locks at fork in the child process.

  • bpo-40149: Implement traverse and clear slots in _abc._abc_data type.

  • bpo-40208: Remove deprecated symtable.SymbolTable.has_exec().

  • bpo-40196: Fix a bug in the symtable module that was causing incorrectly report global variables as local. Patch by Pablo Galindo.

  • bpo-40190: Add support for _SC_AIX_REALMEM to posix.sysconf().

  • bpo-40182: Removed the _field_types attribute of the typing.NamedTuple class.

  • bpo-36517: Multiple inheritance with typing.NamedTuple now raises an error instead of silently ignoring other types.

  • bpo-40126: Fixed reverting multiple patches in unittest.mock. Patcher’s __exit__() is now never called if its __enter__() is failed. Returning true from __exit__() silences now the exception.

  • bpo-40094: CGIHTTPRequestHandler of http.server now logs the CGI script exit code, rather than the CGI script exit status of os.waitpid(). For example, if the script is killed by signal 11, it now logs: “CGI script exit code -11.”

  • bpo-40108: Improve the error message when triying to import a module using runpy and incorrently use the “.py” extension at the end of the module name. Patch by Pablo Galindo.

  • bpo-40094: Add os.waitstatus_to_exitcode() function: convert a wait status to an exit code.

  • bpo-40089: Fix threading._after_fork(): if fork was not called by a thread spawned by threading.Thread, threading._after_fork() now creates a _MainThread instance for _main_thread, instead of a _DummyThread instance.

  • bpo-40089: Add a private _at_fork_reinit() method to _thread.Lock, _thread.RLock, threading.RLock and threading.Condition classes: reinitialize the lock at fork in the child process, reset the lock to the unlocked state. Rename also the private _reset_internal_locks() method of threading.Event to _at_fork_reinit().

  • bpo-25780: Expose CAN_RAW_JOIN_FILTERS in the socket module.

  • bpo-39503: AbstractBasicAuthHandler of urllib.request now parses all WWW-Authenticate HTTP headers and accepts multiple challenges per header: use the realm of the first Basic challenge.

  • bpo-39812: Removed daemon threads from concurrent.futures by adding an internal threading._register_atexit(), which calls registered functions prior to joining all non-daemon threads. This allows for compatibility with subinterpreters, which don’t support daemon threads.

  • bpo-40050: Fix importlib._bootstrap_external: avoid creating a new winreg builtin module if it’s already available in sys.modules, and remove redundant imports.

  • bpo-40014: Fix os.getgrouplist(): if getgrouplist() function fails because the group list is too small, retry with a larger group list. On failure, the glibc implementation of getgrouplist() sets ngroups to the total number of groups. For other implementations, double the group list size.

  • bpo-40017: Add time.CLOCK_TAI constant if the operating system support it.

  • bpo-40016: In re docstring, clarify the relationship between inline and argument compile flags.

  • bpo-39953: Update internal table of OpenSSL error codes in the ssl module.

  • bpo-36144: Added PEP 584 operators to weakref.WeakValueDictionary.

  • bpo-36144: Added PEP 584 operators to weakref.WeakKeyDictionary.

  • bpo-38891: Fix linear runtime behaviour of the __getitem__ and __setitem__ methods in multiprocessing.shared_memory.ShareableList. This avoids quadratic performance when iterating a ShareableList. Patch by Thomas Krennwallner.

  • bpo-39682: Remove undocumented support for closing a pathlib.Path object via its context manager. The context manager magic methods remain, but they are now a no-op, making Path objects immutable.

  • bpo-36144: Added PEP 584 operators (| and |=) to collections.ChainMap.

  • bpo-39011: Normalization of line endings in ElementTree attributes was removed, as line endings which were replaced by entity numbers should be preserved in original form.

  • bpo-38410: Properly handle sys.audit() failures in sys.set_asyncgen_hooks().

  • bpo-36541: lib2to3 now recognizes named assignment expressions (the walrus operator, :=)

  • bpo-35967: In platform, delay the invocation of ‘uname -p’ until the processor attribute is requested.

  • bpo-35113: inspect.getsource() now returns correct source code for inner class with same name as module level class. Decorators are also returned as part of source of the class. Patch by Karthikeyan Singaravelan.

  • bpo-33262: Deprecate passing None as an argument for shlex.split()’s s parameter. Patch by Zackery Spytz.

  • bpo-31758: Prevent crashes when using an uninitialized _elementtree.XMLParser object. Patch by Oren Milman.

Documentation

  • bpo-27635: The pickle documentation incorrectly claimed that __new__ isn’t called by default when unpickling.

  • bpo-39879: Updated Data model docs to include dict() insertion order preservation. Patch by Furkan Onder and Samy Lahfa.

  • bpo-38387: Document PyDoc_STRVAR macro in the C-API reference.

  • bpo-13743: Some methods within xml.dom.minidom.Element class are now better documented.

Tests

  • bpo-31904: Set expected default encoding in test_c_locale_coercion.py for VxWorks RTOS.

  • bpo-40162: Update Travis CI configuration to OpenSSL 1.1.1f.

  • bpo-40146: Update OpenSSL to 1.1.1f in Azure Pipelines.

  • bpo-40094: Add test.support.wait_process() function.

  • bpo-40003: test.bisect_cmd now copies Python command line options like -O or -W. Moreover, emit a warning if test.bisect_cmd is used with -w/--verbose2 option.

  • bpo-39380: Add the encoding in ftplib.FTP and ftplib.FTP_TLS to the constructor as keyword-only and change the default from latin-1 to utf-8 to follow RFC 2640.

  • bpo-39793: Use the same domain when testing make_msgid. Patch by Batuhan Taskaya.

  • bpo-1812: Fix newline handling in doctest.testfile when loading from a package whose loader has a get_data method. Patch by Peter Donis.

Build

  • bpo-38360: Support single-argument form of macOS -isysroot flag.

  • bpo-40158: Fix CPython MSBuild Properties in NuGet Package (build/native/python.props)

  • bpo-38527: Fix configure check on Solaris for “float word ordering”: sometimes, the correct “grep” command was not being used. Patch by Arnon Yaari.

Windows

  • bpo-40164: Updates Windows to OpenSSL 1.1.1f

  • bpo-8901: Ignore the Windows registry when the -E option is used.

macOS

  • bpo-38329: python.org macOS installers now update the Current version symlink of /Library/Frameworks/Python.framework/Versions for 3.9 installs. Previously, Current was only updated for Python 2.x installs. This should make it easier to embed Python 3 into other macOS applications.

  • bpo-40164: Update macOS installer builds to use OpenSSL 1.1.1g.

IDLE

  • bpo-38439: Add a 256×256 pixel IDLE icon to support more modern environments. Created by Andrew Clover. Delete the unused macOS idle.icns icon file.

  • bpo-38689: IDLE will no longer freeze when inspect.signature fails when fetching a calltip.

Tools/Demos

C API

Python 3.9.0 alpha 5

Release date: 2020-03-23

Security

  • bpo-38576: Disallow control characters in hostnames in http.client, addressing CVE-2019-18348. Such potentially malicious header injection URLs now cause a InvalidURL to be raised.

Core and Builtins

  • bpo-40010: Optimize pending calls in multithreaded applications. If a thread different than the main thread schedules a pending call (Py_AddPendingCall()), the bytecode evaluation loop is no longer interrupted at each bytecode instruction to check for pending calls which cannot be executed. Only the main thread can execute pending calls.

    Previously, the bytecode evaluation loop was interrupted at each instruction until the main thread executes pending calls.

  • bpo-1635741: Port _weakref extension module to multiphase initialization (PEP 489).

  • bpo-1635741: Port _collections module to multiphase initialization (PEP 489).

  • bpo-40010: Optimize signal handling in multithreaded applications. If a thread different than the main thread gets a signal, the bytecode evaluation loop is no longer interrupted at each bytecode instruction to check for pending signals which cannot be handled. Only the main thread of the main interpreter can handle signals.

    Previously, the bytecode evaluation loop was interrupted at each instruction until the main thread handles signals.

  • bpo-39984: If Py_AddPendingCall() is called in a subinterpreter, the function is now scheduled to be called from the subinterpreter, rather than being called from the main interpreter. Each subinterpreter now has its own list of scheduled calls.

  • bpo-1635741: Port _heapq module to multiphase initialization.

  • bpo-1635741: Port itertools module to multiphase initialization (PEP 489).

  • bpo-37207: Speed up calls to frozenset() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-39984: subinterpreters: Move _PyRuntimeState.ceval.tracing_possible to PyInterpreterState.ceval.tracing_possible: each interpreter now has its own variable.

  • bpo-37207: Speed up calls to set() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-1635741: Port _statistics module to multiphase initialization (PEP 489).

  • bpo-39968: Use inline function to replace extension modules’ get_module_state macros.

  • bpo-39965: Correctly raise SyntaxError if await is used inside non-async functions and PyCF_ALLOW_TOP_LEVEL_AWAIT is set (like in the asyncio REPL). Patch by Pablo Galindo.

  • bpo-39562: Allow executing asynchronous comprehensions on the top level when the PyCF_ALLOW_TOP_LEVEL_AWAIT flag is given. Patch by Batuhan Taskaya.

  • bpo-37207: Speed up calls to tuple() by using the PEP 590 vectorcall calling convention. Patch by Donghee Na.

  • bpo-38373: Changed list overallocation strategy. It no longer overallocates if the new size is closer to overallocated size than to the old size and adds padding.

  • bpo-39926: Update Unicode database to Unicode version 13.0.0.

  • bpo-19466: Clear the frames of daemon threads earlier during the Python shutdown to call objects destructors. So “unclosed file” resource warnings are now emitted for daemon threads in a more reliable way.

  • bpo-38894: Fix a bug that was causing incomplete results when calling pathlib.Path.glob in the presence of symlinks that point to files where the user does not have read access. Patch by Pablo Galindo and Matt Wozniski.

  • bpo-39877: Fix PyEval_RestoreThread() random crash at exit with daemon threads. It now accesses the _PyRuntime variable directly instead of using tstate->interp->runtime, since tstate can be a dangling pointer after Py_Finalize() has been called. Moreover, the daemon thread now exits before trying to take the GIL.

  • bpo-39871: Fix a possible SystemError in math.{atan2,copysign,remainder}() when the first argument cannot be converted to a float. Patch by Zackery Spytz.

  • bpo-39776: Fix race condition where threads created by PyGILState_Ensure() could get a duplicate id.

    This affects consumers of tstate->id like the contextvar caching machinery, which could return invalid cached objects under heavy thread load (observed in embedded scenarios).

  • bpo-39778: Fixed a crash due to incorrect handling of weak references in collections.OrderedDict classes. Patch by Pablo Galindo.

  • bpo-1635741: Port audioop extension module to multiphase initialization (PEP 489).

  • bpo-39702: Relax decorator grammar restrictions to allow any valid expression (PEP 614).

  • bpo-38091: Tweak import deadlock detection code to not deadlock itself.

  • bpo-1635741: Port _locale extension module to multiphase initialization (PEP 489).

  • bpo-39087: Optimize PyUnicode_AsUTF8() and PyUnicode_AsUTF8AndSize() slightly when they need to create internal UTF-8 cache.

  • bpo-39520: Fix unparsing of ext slices with no items (foo[:,]). Patch by Batuhan Taskaya.

  • bpo-39220: Do not optimize annotations if ‘from __future__ import annotations’ is used. Patch by Pablo Galindo.

  • bpo-35712: Using NotImplemented in a boolean context has been deprecated. Patch contributed by Josh Rosenberg.

  • bpo-22490: Don’t leak environment variable __PYVENV_LAUNCHER__ into the interpreter session on macOS.

Library

  • bpo-39830: Add zipfile.Path to __all__ in the zipfile module.

  • bpo-40000: Improved error messages for validation of ast.Constant nodes. Patch by Batuhan Taskaya.

  • bpo-39999: __module__ of the AST node classes is now set to “ast” instead of “_ast”. Added docstrings for dummy AST node classes and deprecated attributes.

  • bpo-39991: uuid.getnode() now skips IPv6 addresses with the same string length than a MAC address (17 characters): only use MAC addresses.

  • bpo-39988: Deprecated ast.AugLoad and ast.AugStore node classes because they are no longer used.

  • bpo-39656: Ensure bin/python3.# is always present in virtual environments on POSIX platforms - by Anthony Sottile.

  • bpo-39969: Deprecated ast.Param node class because it’s no longer used. Patch by Batuhan Taskaya.

  • bpo-39360: Ensure all workers exit when finalizing a multiprocessing.Pool implicitly via the module finalization handlers of multiprocessing. This fixes a deadlock situation that can be experienced when the Pool is not properly finalized via the context manager or a call to multiprocessing.Pool.terminate. Patch by Batuhan Taskaya and Pablo Galindo.

  • bpo-35370: sys.settrace(), sys.setprofile() and _lsprof.Profiler.enable() now properly report PySys_Audit() error if “sys.setprofile” or “sys.settrace” audit event is denied.

  • bpo-39936: AIX: Fix _aix_support module when the subprocess is not available, when building Python from scratch. It now uses new private _bootsubprocess module, rather than having two implementations depending if subprocess is available or not. So _aix_support.aix_platform() result is now the same if subprocess is available or not.

  • bpo-36144: collections.OrderedDict now implements | and |= (PEP 584).

  • bpo-39652: The column name found in sqlite3.Cursor.description is now truncated on the first ‘[’ only if the PARSE_COLNAMES option is set.

  • bpo-39915: Ensure unittest.mock.AsyncMock.await_args_list has call objects in the order of awaited arguments instead of using unittest.mock.Mock.call_args which has the last value of the call. Patch by Karthikeyan Singaravelan.

  • bpo-36144: Updated os.environ and os.environb to support PEP 584’s merge (|) and update (|=) operators.

  • bpo-38662: The ensurepip module now invokes pip via the runpy module. Hence it is no longer tightly coupled with the internal API of the bundled pip version, allowing easier updates to a newer pip version both internally and for distributors.

  • bpo-38075: Fix the random.Random.seed() method when a bool is passed as the seed.

  • bpo-39916: More reliable use of os.scandir() in Path.glob(). It no longer emits a ResourceWarning when interrupted.

  • bpo-39850: multiprocessing now supports abstract socket addresses (if abstract sockets are supported in the running platform). When creating arbitrary addresses (like when default-constructing multiprocessing.connection.Listener objects) abstract sockets are preferred to avoid the case when the temporary-file-generated address is too large for an AF_UNIX socket address. Patch by Pablo Galindo.

  • bpo-36287: ast.dump() no longer outputs optional fields and attributes with default values. The default values for optional fields and attributes of AST nodes are now set as class attributes (e.g. Constant.kind is set to None).

  • bpo-39889: Fixed ast.unparse() for extended slices containing a single element (e.g. a[i:j,]). Remove redundant tuples when index with a tuple (e.g. a[i, j]).

  • bpo-39828: Fix json.tool to catch BrokenPipeError. Patch by Donghee Na.

  • bpo-13487: Avoid a possible “RuntimeError: dictionary changed size during iteration” from inspect.getmodule() when it tried to loop through sys.modules.

  • bpo-39674: Revert “bpo-37330: open() no longer accept ‘U’ in file mode”. The “U” mode of open() is kept in Python 3.9 to ease transition from Python 2.7, but will be removed in Python 3.10.

  • bpo-28577: The hosts method on 32-bit prefix length IPv4Networks and 128-bit prefix IPv6Networks now returns a list containing the single Address instead of an empty list.

  • bpo-39826: Add getConnection method to logging HTTPHandler to enable custom connections.

  • bpo-39763: Reimplement distutils.spawn.spawn() function with the subprocess module.

  • bpo-39794: Add –without-decimal-contextvar build option. This enables a thread-local rather than a coroutine local context.

  • bpo-36144: collections.defaultdict now implements | (PEP 584).

  • bpo-39517: Fix runpy.run_path() when using pathlike objects

  • bpo-39775: Change inspect.Signature.parameters back to collections.OrderedDict. This was changed to dict in Python 3.9.0a4.

  • bpo-39678: Refactor queue_manager in concurrent.futures.ProcessPoolExecutor to make it easier to maintain.

  • bpo-39764: Fix AttributeError when calling get_stack on a PyAsyncGenObject Task

  • bpo-39769: The compileall.compile_dir() function’s ddir parameter and the compileall command line flag -d no longer write the wrong pathname to the generated pyc file for submodules beneath the root of the directory tree being compiled. This fixes a regression introduced with Python 3.5.

  • bpo-36144: types.MappingProxyType objects now support the merge (|) operator from PEP 584.

  • bpo-38691: The importlib module now ignores the PYTHONCASEOK environment variable when the -E or -I command line options are being used.

  • bpo-39719: Remove tempfile.SpooledTemporaryFile.softspace() as files no longer have the softspace attribute in Python 3. Patch by Shantanu.

  • bpo-39667: Improve pathlib.Path compatibility on zipfile.Path and correct performance degradation as found in zipp 3.0.

  • bpo-39638: Keep ASDL signatures in the docstrings for AST nodes. Patch by Batuhan Taskaya

  • bpo-39639: Deprecated ast.Suite node class because it’s no longer used. Patch by Batuhan Taskaya.

  • bpo-39609: Add thread_name_prefix to default asyncio executor

  • bpo-39548: Fix handling of header in urllib.request.AbstractDigestAuthHandler when the optional qop parameter is not present.

  • bpo-39509: HTTP status codes 103 EARLY_HINTS and 425 TOO_EARLY are added to http.HTTPStatus. Patch by Donghee Na.

  • bpo-39507: Adding HTTP status 418 “I’m a Teapot” to HTTPStatus in http library. Patch by Ross Rhodes.

  • bpo-39495: Remove default value from attrs parameter of xml.etree.ElementTree.TreeBuilder.start() for consistency between Python and C implementations.

  • bpo-38971: Open issue in the BPO indicated a desire to make the implementation of codecs.open() at parity with io.open(), which implements a try/except to assure file stream gets closed before an exception is raised.

  • bpo-38641: Added starred expressions support to return and yield statements for lib2to3. Patch by Vlad Emelianov.

  • bpo-37534: When using minidom module to generate XML documents the ability to add Standalone Document Declaration is added. All the changes are made to generate a document in compliance with Extensible Markup Language (XML) 1.0 (Fifth Edition) W3C Recommendation (available here: https://www.w3.org/TR/xml/#sec-prolog-dtd).

  • bpo-34788: Add support for scoped IPv6 addresses to ipaddress. Patch by Oleksandr Pavliuk.

  • bpo-34822: Simplified AST for subscription. Simple indices are now represented by their value, extended slices are represented as tuples. ast classes Index and ExtSlice are considered deprecated and will be removed in future Python versions. In the meantime, Index(value) now returns a value itself, ExtSlice(slices) returns Tuple(slices, Load()).

Documentation

  • bpo-39868: Updated the Language Reference for PEP 572.

  • bpo-13790: Change ‘string’ to ‘specification’ in format doc.

  • bpo-17422: The language reference no longer restricts default class namespaces to dicts only.

  • bpo-39530: Fix misleading documentation about mixed-type numeric comparisons.

  • bpo-39718: Update token documentation to reflect additions in Python 3.8

  • bpo-39677: Changed operand name of MAKE_FUNCTION from argc to flags for module dis

Tests

  • bpo-40019: test_gdb now skips tests if it detects that gdb failed to read debug information because the Python binary is optimized.

  • bpo-27807: test_site.test_startup_imports() is now skipped if a path of sys.path contains a .pth file.

  • bpo-26067: Do not fail test_shutil test_chown test when uid or gid of user cannot be resolved to a name.

  • bpo-39855: test_subprocess.test_user() now skips the test on an user name if the user name doesn’t exist. For example, skip the test if the user “nobody” doesn’t exist on Linux.

Build

  • bpo-39761: Fix build with DTrace but without additional DFLAGS.

  • bpo-39763: setup.py now uses a basic implementation of the subprocess module if the subprocess module is not available: before required C extension modules are built.

  • bpo-1294959: Add --with-platlibdir option to the configure script: name of the platform-specific library directory, stored in the new sys.platlibdir attribute. It is used to build the path of platform-specific extension modules and the path of the standard library. It is equal to "lib" on most platforms. On Fedora and SuSE, it is equal to "lib64" on 64-bit platforms. Patch by Jan Matějek, Matěj Cepl, Charalampos Stratakis and Victor Stinner.

Windows

  • bpo-39930: Ensures the required vcruntime140.dll is included in install packages.

  • bpo-39847: Avoid hang when computer is hibernated whilst waiting for a mutex (for lock-related objects from threading) around 49-day uptime.

  • bpo-38597: distutils will no longer statically link vcruntime140.dll when a redistributable version is unavailable. All future releases of CPython will include a copy of this DLL to ensure distributed extensions can continue to load.

  • bpo-38380: Update Windows builds to use SQLite 3.31.1

  • bpo-39789: Update Windows release build machines to Visual Studio 2019 (MSVC 14.2).

  • bpo-34803: Package for nuget.org now includes repository reference and bundled icon image.

macOS

  • bpo-38380: Update macOS builds to use SQLite 3.31.1

IDLE

  • bpo-27115: For ‘Go to Line’, use a Query box subclass with IDLE standard behavior and improved error checking.

  • bpo-39885: Since clicking to get an IDLE context menu moves the cursor, any text selection should be and now is cleared.

  • bpo-39852: Edit “Go to line” now clears any selection, preventing accidental deletion. It also updates Ln and Col on the status bar.

  • bpo-39781: Selecting code context lines no longer causes a jump.

Tools/Demos

  • bpo-36184: Port python-gdb.py to FreeBSD. python-gdb.py now checks for “take_gil” function name to check if a frame tries to acquire the GIL, instead of checking for “pthread_cond_timedwait” which is specific to Linux and can be a different condition than the GIL.

  • bpo-38080: Added support to fix getproxies in the lib2to3.fixes.fix_urllib module. Patch by José Roberto Meza Cabrera.

C API

Python 3.9.0 alpha 4

Release date: 2020-02-25

Security

  • bpo-39184: Add audit events to functions in fcntl, msvcrt, os, resource, shutil, signal and syslog.

  • bpo-39401: Avoid unsafe DLL load at startup on Windows 7 and earlier.

  • bpo-39184: Add audit events to command execution functions in os and pty modules.

Core and Builtins

  • bpo-39382: Fix a use-after-free in the single inheritance path of issubclass(), when the __bases__ of an object has a single reference, and so does its first item. Patch by Yonatan Goldschmidt.

  • bpo-39573: Update clinic tool to use Py_IS_TYPE(). Patch by Donghee Na.

  • bpo-39619: Enable use of os.chroot() on HP-UX systems.

  • bpo-39573: Add Py_IS_TYPE() static inline function to check whether the object o type is type.

  • bpo-39606: Fix regression caused by fix for bpo-39386, that prevented calling aclose on an async generator that had already been closed or exhausted.

  • bpo-39579: Change the ending column offset of Attribute nodes constructed in ast_for_dotted_name to point at the end of the current node and not at the end of the last NAME node.

  • bpo-1635741: Port _crypt extension module to multiphase initialization (PEP 489).

  • bpo-1635741: Port _contextvars extension module to multiphase initialization (PEP 489).

  • bpo-39510: Fix segfault in readinto() method on closed BufferedReader.

  • bpo-39502: Fix time.localtime() on 64-bit AIX to support years before 1902 and after 2038. Patch by M Felt.

  • bpo-39492: Fix a reference cycle in the C Pickler that was preventing the garbage collection of deleted, pickled objects.

  • bpo-39453: Fixed a possible crash in list.__contains__() when a list is changed during comparing items. Patch by Donghee Na.

  • bpo-39434: floor division of float operation now has a better performance. Also the message of ZeroDivisionError for this operation is updated. Patch by Donghee Na.

  • bpo-1635741: Port _codecs extension module to multiphase initialization (PEP 489).

  • bpo-1635741: Port _bz2 extension module to multiphase initialization (PEP 489).

  • bpo-1635741: Port _abc extension module to multiphase initialization (PEP 489).

  • bpo-39320: Replace two complex bytecodes for building dicts with two simpler ones. The new bytecodes DICT_MERGE and DICT_UPDATE have been added The old bytecodes BUILD_MAP_UNPACK and BUILD_MAP_UNPACK_WITH_CALL have been removed.

  • bpo-39219: Syntax errors raised in the tokenizer now always set correct “text” and “offset” attributes.

  • bpo-36051: Drop the GIL during large bytes.join operations. Patch by Bruce Merry.

  • bpo-38960: Fix DTrace build issues on FreeBSD. Patch by David Carlier.

  • bpo-37207: Speed up calls to range() by about 30%, by using the PEP 590 vectorcall calling convention. Patch by Mark Shannon.

  • bpo-36144: dict (and collections.UserDict) objects now support PEP 584’s merge (|) and update (|=) operators. Patch by Brandt Bucher.

  • bpo-32856: Optimized the idiom for assignment a temporary variable in comprehensions. Now for y in [expr] in comprehensions is as fast as a simple assignment y = expr.

Library

  • bpo-30566: Fix IndexError when trying to decode an invalid string with punycode codec.

  • bpo-39649: Remove obsolete check for __args__ in bdb.Bdb.format_stack_entry.

  • bpo-39648: Expanded math.gcd() and math.lcm() to handle multiple arguments.

  • bpo-39681: Fix a regression where the C pickle module wouldn’t allow unpickling from a file-like object that doesn’t expose a readinto() method.

  • bpo-35950: Raise io.UnsupportedOperation in io.BufferedReader.truncate() when it is called on a read-only io.BufferedReader instance.

  • bpo-39479: Add math.lcm() function: least common multiple.

  • bpo-39674: Revert “Do not expose abstract collection classes in the collections module” change (bpo-25988). Aliases to ABC like collections.Mapping are kept in Python 3.9 to ease transition from Python 2.7, but will be removed in Python 3.10.

  • bpo-39104: Fix hanging ProcessPoolExcutor on shutdown(wait=False) when a task has failed pickling.

  • bpo-39627: Fixed TypedDict totality check for inherited keys.

  • bpo-39474: Fixed starting position of AST for expressions like (a)(b), (a)[b] and (a).b.

  • bpo-21016: The pydoc and trace modules now use the sysconfig module to get the path to the Python standard library, to support uncommon installation path like /usr/lib64/python3.9/ on Fedora. Patch by Jan Matějek.

  • bpo-39590: Collections.deque now holds strong references during deque.__contains__ and deque.count, fixing crashes.

  • bpo-39586: The distutils bdist_msi command is deprecated in Python 3.9, use bdist_wheel (wheel packages) instead.

  • bpo-39595: Improved performance of zipfile.Path for files with a large number of entries. Also improved performance and fixed minor issue as published with importlib_metadata 1.5.

  • bpo-39350: Fix regression in fractions.Fraction if the numerator and/or the denominator is an int subclass. The math.gcd() function is now used to normalize the numerator and denominator. math.gcd() always return a int type. Previously, the GCD type depended on numerator and denominator.

  • bpo-39567: Added audit for os.walk(), os.fwalk(), pathlib.Path.glob() and pathlib.Path.rglob().

  • bpo-39559: Remove unused, undocumented argument getters from uuid.getnode()

  • bpo-38149: sys.audit() is now called only once per call of glob.glob() and glob.iglob().

  • bpo-39546: Fix a regression in ArgumentParser where allow_abbrev=False was ignored for long options that used a prefix character other than “-“.

  • bpo-39450: Striped whitespace from docstring before returning it from unittest.case.shortDescription().

  • bpo-12915: A new function resolve_name has been added to the pkgutil module. This resolves a string of the form 'a.b.c.d' or 'a.b:c.d' to an object. In the example, a.b is a package/module and c.d is an object within that package/module reached via recursive attribute access.

  • bpo-39353: The binascii.crc_hqx() function is no longer deprecated.

  • bpo-39493: Mark typing.IO.closed as a property

  • bpo-39491: Add typing.Annotated and include_extras parameter to typing.get_type_hints() as part of PEP 593. Patch by Till Varoquaux, documentation by Till Varoquaux and Konstantin Kashin.

  • bpo-39485: Fix a bug in unittest.mock.create_autospec() that would complain about the wrong number of arguments for custom descriptors defined in an extension module returning functions.

  • bpo-38932: Mock fully resets child objects on reset_mock(). Patch by Vegard Stikbakke

  • bpo-39082: Allow AsyncMock to correctly patch static/class methods

  • bpo-39432: Implement PEP-489 algorithm for non-ascii “PyInit_…” symbol names in distutils to make it export the correct init symbol also on Windows.

  • bpo-18819: Omit devmajor and devminor fields for non-device files in tarfile archives, enabling bit-for-bit compatibility with GNU tar(1).

  • bpo-39349: Added a new cancel_futures parameter to concurrent.futures.Executor.shutdown() that cancels all pending futures which have not started running, instead of waiting for them to complete before shutting down the executor.

  • bpo-39274: bool(fraction.Fraction) now returns a boolean even if (numerator != 0) does not return a boolean (ex: numpy number).

  • bpo-34793: Remove support for with (await asyncio.lock): and with (yield from asyncio.lock):. The same is correct for asyncio.Condition and asyncio.Semaphore.

  • bpo-25597: Ensure, if wraps is supplied to unittest.mock.MagicMock, it is used to calculate return values for the magic methods instead of using the default return values. Patch by Karthikeyan Singaravelan.

  • bpo-36350: inspect.Signature.parameters and inspect.BoundArguments.arguments are now dicts instead of OrderedDicts. Patch contributed by Rémi Lapeyre.

  • bpo-35727: Fix sys.exit() and sys.exit(None) exit code propagation when used in multiprocessing.Process.

  • bpo-32173: * Add lazycache function to __all__. * Use dict.clear to clear the cache. * Refactoring getline function and checkcache function.

Documentation

  • bpo-17422: The language reference now specifies restrictions on class namespaces. Adapted from a patch by Ethan Furman.

  • bpo-39572: Updated documentation of total flag of TypedDict.

  • bpo-39654: In pyclbr doc, update ‘class’ to ‘module’ where appropriate and add readmodule comment. Patch by Hakan Çelik.

  • bpo-39153: Clarify refcounting semantics for the following functions: - PyObject_SetItem - PyMapping_SetItemString - PyDict_SetItem - PyDict_SetItemString

  • bpo-39392: Explain that when filling with turtle, overlap regions may be left unfilled.

  • bpo-39369: Update mmap readline method description. The fact that the readline method does update the file position should not be ignored since this might give the impression for the programmer that it doesn’t update it.

  • bpo-9056: Include subsection in TOC for PDF version of docs.

Tests

Build

  • bpo-39489: Remove COUNT_ALLOCS special build.

Windows

  • bpo-39553: Delete unused code related to SxS manifests.

  • bpo-39439: Honor the Python path when a virtualenv is active on Windows.

  • bpo-39393: Improve the error message when attempting to load a DLL with unresolved dependencies.

  • bpo-38883: home() and expanduser() on Windows now prefer USERPROFILE and no longer use HOME, which is not normally set for regular user accounts. This makes them again behave like os.path.expanduser(), which was changed to ignore HOME in 3.8, see bpo-36264.

  • bpo-39185: The build.bat script has additional options for very-quiet output (-q) and very-verbose output (-vv)

IDLE

  • bpo-39663: Add tests for pyparse find_good_parse_start().

  • bpo-39600: In the font configuration window, remove duplicated font names.

  • bpo-30780: Add remaining configdialog tests for buttons and highlights and keys tabs.

  • bpo-39388: IDLE Settings Cancel button now cancels pending changes

  • bpo-38792: Close an IDLE shell calltip if a KeyboardInterrupt or shell restart occurs. Patch by Zackery Spytz.

C API

  • bpo-35081: Move the bytes_methods.h header file to the internal C API as pycore_bytes_methods.h: it only contains private symbols (prefixed by _Py), except of the PyDoc_STRVAR_shared() macro.

  • bpo-35081: Move the dtoa.h header file to the internal C API as pycore_dtoa.h: it only contains private functions (prefixed by _Py). The math and cmath modules must now be compiled with the Py_BUILD_CORE macro defined.

  • bpo-39573: Add Py_SET_SIZE() function to set the size of an object.

  • bpo-39500: PyUnicode_IsIdentifier() does not call Py_FatalError() anymore if the string is not ready.

  • bpo-39573: Add Py_SET_TYPE() function to set the type of an object.

  • bpo-39573: Add a Py_SET_REFCNT() function to set the reference counter of an object.

  • bpo-39542: Convert PyType_HasFeature(), PyType_Check() and PyType_CheckExact() macros to static inline functions.

  • bpo-39542: In the limited C API, PyObject_INIT() and PyObject_INIT_VAR() are now defined as aliases to PyObject_Init() and PyObject_InitVar() to make their implementation opaque. It avoids to leak implementation details in the limited C API. Exclude the following functions from the limited C API: _Py_NewReference(), _Py_ForgetReference(), _PyTraceMalloc_NewReference() and _Py_GetRefTotal().

  • bpo-39542: Exclude trashcan mechanism from the limited C API: it requires access to PyTypeObject and PyThreadState structure fields, whereas these structures are opaque in the limited C API.

  • bpo-39511: The PyThreadState_Clear() function now calls the PyThreadState.on_delete callback. Previously, that happened in PyThreadState_Delete().

  • bpo-38076: Fix to clear the interpreter state only after clearing module globals to guarantee module state access from C Extensions during runtime destruction

  • bpo-39245: The Vectorcall API (PEP 590) was made public, adding the functions PyObject_Vectorcall, PyObject_VectorcallMethod, PyVectorcall_Function, PyObject_CallOneArg, PyObject_CallMethodNoArgs, PyObject_CallMethodOneArg, PyObject_FastCallDict, and the flag Py_TPFLAGS_HAVE_VECTORCALL.

Python 3.9.0 alpha 3

Release date: 2020-01-24

Core and Builtins

  • bpo-39427: Document all possibilities for the -X options in the command line help section. Patch by Pablo Galindo.

  • bpo-39421: Fix possible crashes when operating with the functions in the heapq module and custom comparison operators.

  • bpo-39386: Prevent double awaiting of async iterator.

  • bpo-17005: Add functools.TopologicalSorter to the functools module to offers functionality to perform topological sorting of graphs. Patch by Pablo Galindo, Tim Peters and Larry Hastings.

  • bpo-39320: Replace four complex bytecodes for building sequences with three simpler ones.

    The following four bytecodes have been removed:

    • BUILD_LIST_UNPACK

    • BUILD_TUPLE_UNPACK

    • BUILD_SET_UNPACK

    • BUILD_TUPLE_UNPACK_WITH_CALL

    The following three bytecodes have been added:

    • LIST_TO_TUPLE

    • LIST_EXTEND

    • SET_UPDATE

  • bpo-39336: Import loaders which publish immutable module objects can now publish immutable packages in addition to individual modules.

  • bpo-39322: Added a new function gc.is_finalized() to check if an object has been finalized by the garbage collector. Patch by Pablo Galindo.

  • bpo-39048: Improve the displayed error message when incorrect types are passed to async with statements by looking up the __aenter__() special method before the __aexit__() special method when entering an asynchronous context manager. Patch by Géry Ogam.

  • bpo-39235: Fix AST end location for lone generator expression in function call, e.g. f(i for i in a).

  • bpo-39209: Correctly handle multi-line tokens in interactive mode. Patch by Pablo Galindo.

  • bpo-1635741: Port _json extension module to multiphase initialization (PEP 489).

  • bpo-39216: Fix constant folding optimization for positional only arguments - by Anthony Sottile.

  • bpo-39215: Fix SystemError when nested function has annotation on positional-only argument - by Anthony Sottile.

  • bpo-39200: Correct the error message when calling the min() or max() with no arguments. Patch by Donghee Na.

  • bpo-39200: Correct the error message when trying to construct range objects with no arguments. Patch by Pablo Galindo.

  • bpo-39166: Fix incorrect line execution reporting in trace functions when tracing the last iteration of asynchronous for loops. Patch by Pablo Galindo.

  • bpo-39114: Fix incorrect line execution reporting in trace functions when tracing exception handlers with name binding. Patch by Pablo Galindo.

  • bpo-39156: Split the COMPARE_OP bytecode instruction into four distinct instructions.

    • COMPARE_OP for rich comparisons

    • IS_OP for ‘is’ and ‘is not’ tests

    • CONTAINS_OP for ‘in’ and ‘is not’ tests

    • JUMP_IF_NOT_EXC_MATCH for checking exceptions in ‘try-except’ statements.

    This improves the clarity of the interpreter and should provide a modest speedup.

  • bpo-38588: Fix possible crashes in dict and list when calling PyObject_RichCompareBool().

  • bpo-13601: By default, sys.stderr is line-buffered now, even if stderr is redirected to a file. You can still make sys.stderr unbuffered by passing the -u command-line option or setting the PYTHONUNBUFFERED environment variable.

    (Contributed by Jendrik Seipp in bpo-13601.)

  • bpo-38610: Fix possible crashes in several list methods by holding strong references to list elements when calling PyObject_RichCompareBool().

  • bpo-32021: Include brotli .br encoding in mimetypes encodings_map

Library

  • bpo-39430: Fixed race condition in lazy imports in tarfile.

  • bpo-39413: The os.unsetenv() function is now also available on Windows.

  • bpo-39390: Fixed a regression with the ignore callback of shutil.copytree(). The argument types are now str and List[str] again.

  • bpo-39395: The os.putenv() and os.unsetenv() functions are now always available.

  • bpo-39406: If setenv() C function is available, os.putenv() is now implemented with setenv() instead of putenv(), so Python doesn’t have to handle the environment variable memory.

  • bpo-39396: Fix math.nextafter(-0.0, +0.0) on AIX 7.1.

  • bpo-29435: Allow tarfile.is_tarfile() to be used with file and file-like objects, like zipfile.is_zipfile(). Patch by William Woodruff.

  • bpo-39377: Removed encoding option from json.loads(). It has been deprecated since Python 3.1.

  • bpo-39389: Write accurate compression level metadata in gzip archives, rather than always signaling maximum compression.

  • bpo-39366: The previously deprecated xpath() and xgtitle() methods of nntplib.NNTP have been removed.

  • bpo-39357: Remove the buffering parameter of bz2.BZ2File. Since Python 3.0, it was ignored and using it was emitting DeprecationWarning. Pass an open file object, to control how the file is opened. The compresslevel parameter becomes keyword-only.

  • bpo-39353: Deprecate binhex4 and hexbin4 standards. Deprecate the binhex module and the following binascii functions: b2a_hqx(), a2b_hqx(), rlecode_hqx(), rledecode_hqx(), crc_hqx().

  • bpo-39351: Remove base64.encodestring() and base64.decodestring(), aliases deprecated since Python 3.1: use base64.encodebytes() and base64.decodebytes() instead.

  • bpo-39350: Remove fractions.gcd() function, deprecated since Python 3.5 (bpo-22486): use math.gcd() instead.

  • bpo-39329: LMTP constructor now has an optional timeout parameter. Patch by Donghee Na.

  • bpo-39313: Add a new exec_function option (–exec-function in the CLI) to RefactoringTool for making exec a function. Patch by Batuhan Taskaya.

  • bpo-39259: FTP_TLS and FTP_TLS now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-39259: SMTP and SMTP_SSL now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-39310: Add math.ulp(): return the value of the least significant bit of a float.

  • bpo-39297: Improved performance of importlib.metadata distribution discovery and resilients to inaccessible sys.path entries (importlib_metadata v1.4.0).

  • bpo-39259: NNTP and NNTP_SSL now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-38901: When you specify prompt=’.’ or equivalently python -m venv –prompt . … the basename of the current directory is used to set the created venv’s prompt when it’s activated.

  • bpo-39288: Add math.nextafter(): return the next floating-point value after x towards y.

  • bpo-39259: POP3 and POP3_SSL now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. Patch by Donghee Na.

  • bpo-39242: Updated the Gmane domain from news.gmane.org to news.gmane.io which is used for examples of NNTP news reader server and nntplib tests.

  • bpo-35292: Proxy the SimpleHTTPRequestHandler.guess_type to mimetypes.guess_type so the mimetypes.init is called lazily to avoid unnecessary costs when http.server module is imported.

  • bpo-39239: The select.epoll.unregister() method no longer ignores the EBADF error.

  • bpo-38907: In http.server script, restore binding to IPv4 on Windows.

  • bpo-39152: Fix ttk.Scale.configure([name]) to return configuration tuple for name or all options. Giovanni Lombardo contributed part of the patch.

  • bpo-39198: If an exception were to be thrown in Logger.isEnabledFor (say, by asyncio timeouts or stopit) , the logging global lock may not be released appropriately, resulting in deadlock. This change wraps that block of code with try...finally to ensure the lock is released.

  • bpo-39191: Perform a check for running loop before starting a new task in loop.run_until_complete() to fail fast; it prevents the side effect of new task spawning before exception raising.

  • bpo-38871: Correctly parenthesize filter-based statements that contain lambda expressions in lib2to3. Patch by Donghee Na.

  • bpo-39142: A change was made to logging.config.dictConfig to avoid converting instances of named tuples to ConvertingTuple. It’s assumed that named tuples are too specialised to be treated like ordinary tuples; if a user of named tuples requires ConvertingTuple functionality, they will have to implement that themselves in their named tuple class.

  • bpo-39158: ast.literal_eval() now supports empty sets.

  • bpo-39129: Fix import path for asyncio.TimeoutError

  • bpo-39057: urllib.request.proxy_bypass_environment() now ignores leading dots and no longer ignores a trailing newline.

  • bpo-39056: Fixed handling invalid warning category in the -W option. No longer import the re module if it is not needed.

  • bpo-39055: base64.b64decode() with validate=True raises now a binascii.Error if the input ends with a single \n.

  • bpo-21600: Fix mock.patch.stopall() to stop active patches that were created with mock.patch.dict().

  • bpo-39019: Implement dummy __class_getitem__ for tempfile.SpooledTemporaryFile.

  • bpo-39019: Implement dummy __class_getitem__ for subprocess.Popen, subprocess.CompletedProcess

  • bpo-38914: Adjusted the wording of the warning issued by distutils’ check command when the author and maintainer fields are supplied but no corresponding e-mail field (author_email or maintainer_email) is found. The wording now reflects the fact that these fields are suggested, but not required. Patch by Juergen Gmach.

  • bpo-38878: Fixed __subclasshook__ of os.PathLike to return a correct result upon inheritance. Patch by Bar Harel.

  • bpo-38615: IMAP4 and IMAP4_SSL now have an optional timeout parameter for their constructors. Also, the open() method now has an optional timeout parameter with this change. The overridden methods of IMAP4_SSL and IMAP4_stream were applied to this change. Patch by Donghee Na.

  • bpo-35182: Fixed Popen.communicate() subsequent call crash when the child process has already closed any piped standard stream, but still continues to be running. Patch by Andriy Maletsky.

  • bpo-38630: On Unix, subprocess.Popen.send_signal() now polls the process status. Polling reduces the risk of sending a signal to the wrong process if the process completed, the subprocess.Popen.returncode attribute is still None, and the pid has been reassigned (recycled) to a new different process.

  • bpo-38536: Removes trailing space in formatted currency with international=True and a locale with symbol following value. E.g. locale.currency(12.34, international=True) returned '12,34 EUR ' instead of '12,34 EUR'.

  • bpo-38473: Use signature from inner mock for autospecced methods attached with unittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.

  • bpo-38361: Fixed an issue where ident could include a leading path separator when syslog.openlog() was called without arguments.

  • bpo-38293: Add copy.copy() and copy.deepcopy() support to property() objects.

  • bpo-37958: Added the pstats.Stats.get_profile_dict() method to return the profile data as a StatsProfile instance.

  • bpo-28367: Termios magic constants for the following baud rates: - B500000 - B576000 - B921600 - B1000000 - B1152000 - B1500000 - B2000000 - B2500000 - B3000000 - B3500000 - B4000000 Patch by Andrey Smirnov

Documentation

  • bpo-39381: Mention in docs that asyncio.get_event_loop() implicitly creates new event loop only if called from the main thread.

  • bpo-38918: Add an entry for __module__ in the “function” & “method” sections of the inspect docs’ Types and members table.

  • bpo-3530: In the ast module documentation, fix a misleading NodeTransformer example and add advice on when to use the fix_missing_locations function.

Build

  • bpo-39395: On non-Windows platforms, the setenv() and unsetenv() functions are now required to build Python.

  • bpo-39160: Updated the documentation in ./configure --help to show default values, reference documentation where required and add additional explanation where needed.

  • bpo-39144: The ctags and etags build targets both include Modules/_ctypes and Python standard library source files.

IDLE

  • bpo-39050: Make IDLE Settings dialog Help button work again.

  • bpo-34118: Tag memoryview, range, and tuple as classes, the same as list, etcetera, in the library manual built-in functions list.

  • bpo-32989: Add tests for editor newline_and_indent_event method. Remove dead code from pyparse find_good_parse_start method.

C API

  • bpo-39372: Clean header files of interfaces defined but with no implementation. The public API symbols being removed are: _PyBytes_InsertThousandsGroupingLocale, _PyBytes_InsertThousandsGrouping, _Py_InitializeFromArgs, _Py_InitializeFromWideArgs, _PyFloat_Repr, _PyFloat_Digits, _PyFloat_DigitsInit, PyFrame_ExtendStack, _PyAIterWrapper_Type, PyNullImporter_Type, PyCmpWrapper_Type, PySortWrapper_Type, PyNoArgsFunction.

  • bpo-39164: Add a private _PyErr_GetExcInfo() function to retrieve exception information of the specified Python thread state.

Python 3.9.0 alpha 2

Release date: 2019-12-18

Security

  • bpo-38945: Newline characters have been escaped when performing uu encoding to prevent them from overflowing into to content section of the encoded file. This prevents malicious or accidental modification of data during the decoding process.

  • bpo-37228: Due to significant security concerns, the reuse_address parameter of asyncio.loop.create_datagram_endpoint() is no longer supported. This is because of the behavior of SO_REUSEADDR in UDP. For more details, see the documentation for loop.create_datagram_endpoint(). (Contributed by Kyle Stanley, Antoine Pitrou, and Yury Selivanov in bpo-37228.)

  • bpo-38804: Fixes a ReDoS vulnerability in http.cookiejar. Patch by Ben Caller.

Core and Builtins

  • bpo-39028: Slightly improve the speed of keyword argument parsing with many kwargs by strengthening the assumption that kwargs are interned strings.

  • bpo-39080: Fix the value of end_col_offset for Starred Expression AST nodes when they are among the elements in the args attribute of Call AST nodes.

  • bpo-39031: When parsing an “elif” node, lineno and col_offset of the node now point to the “elif” keyword and not to its condition, making it consistent with the “if” node. Patch by Lysandros Nikolaou.

  • bpo-20443: In Python 3.9.0a1, sys.argv[0] was made an absolute path if a filename was specified on the command line. Revert this change, since most users expect sys.argv to be unmodified.

  • bpo-39008: PySys_Audit() now requires Py_ssize_t to be used for size arguments in the format string, regardless of whether PY_SSIZE_T_CLEAN was defined at include time.

  • bpo-38673: In REPL mode, don’t switch to PS2 if the line starts with comment or whitespace. Based on work by Batuhan Taşkaya.

  • bpo-38922: Calling replace on a code object now raises the code.__new__ audit event.

  • bpo-38920: Add audit hooks for when sys.excepthook() and sys.unraisablehook() are invoked.

  • bpo-38892: Improve documentation for audit events table and functions.

  • bpo-38852: Set the thread stack size to 8 Mb for debug builds on android platforms.

  • bpo-38858: Each Python subinterpreter now has its own “small integer singletons”: numbers in [-5; 257] range. It is no longer possible to change the number of small integers at build time by overriding NSMALLNEGINTS and NSMALLPOSINTS macros: macros should now be modified manually in pycore_pystate.h header file.

  • bpo-36854: The garbage collector state becomes per interpreter (PyInterpreterState.gc), rather than being global (_PyRuntimeState.gc).

  • bpo-38835: The PyFPE_START_PROTECT() and PyFPE_END_PROTECT() macros are empty: they have been doing nothing for the last year, so stop using them.

  • bpo-38328: Sped up the creation time of constant list and set displays. Patch by Brandt Bucher.

  • bpo-38707: MainThread.native_id is now correctly reset in child processes spawned using multiprocessing.Process, instead of retaining the parent’s value.

  • bpo-38629: Added __floor__ and __ceil__ methods to float object. Patch by Batuhan Taşkaya.

  • bpo-27145: int + int and int - int operators can now return small integer singletons. Patch by hongweipeng.

  • bpo-38021: Provide a platform tag for AIX that is sufficient for PEP425 binary distribution identification. Patch by Michael Felt.

  • bpo-35409: Ignore GeneratorExit exceptions when throwing an exception into the aclose coroutine of an asynchronous generator.

  • bpo-33387: Removed WITH_CLEANUP_START, WITH_CLEANUP_FINISH, BEGIN_FINALLY, END_FINALLY, CALL_FINALLY and POP_FINALLY bytecodes. Replaced with RERAISE and WITH_EXCEPT_START bytecodes. The compiler now generates different code for exceptional and non-exceptional branches for ‘with’ and ‘try-except’ statements. For ‘try-finally’ statements the ‘finally’ block is replicated for each exit from the ‘try’ body.

Library

  • bpo-39033: Fix NameError in zipimport. Patch by Karthikeyan Singaravelan.

  • bpo-39022: Update importlib.metadata to include improvements from importlib_metadata 1.3 including better serialization of EntryPoints and improved documentation for custom finders.

  • bpo-39006: Fix asyncio when the ssl module is missing: only check for ssl.SSLSocket instance if the ssl module is available.

  • bpo-38708: Fix a potential IndexError in email parser when parsing an empty msg-id.

  • bpo-38698: Add a new InvalidMessageID token to email parser to represent invalid Message-ID headers. Also, add defects when there is remaining value after parsing the header.

  • bpo-38994: Implement __class_getitem__ for os.PathLike, pathlib.Path.

  • bpo-38979: Return class from ContextVar.__class_getitem__ to simplify subclassing.

  • bpo-38978: Implement __class_getitem__ on asyncio objects (Future, Task, Queue). Patch by Batuhan Taskaya.

  • bpo-38916: array.array: Remove tostring() and fromstring() methods. They were aliases to tobytes() and frombytes(), deprecated since Python 3.2.

  • bpo-38986: Make repr of C accelerated TaskWakeupMethWrapper the same as of pure Python version.

  • bpo-38982: Fix asyncio PidfdChildWatcher: handle waitpid() error. If waitpid() is called elsewhere, waitpid() call fails with ChildProcessError: use return code 255 in this case, and log a warning. It ensures that the pidfd file descriptor is closed if this error occurs.

  • bpo-38529: Drop too noisy asyncio warning about deletion of a stream without explicit .close() call.

  • bpo-27413: Added ability to pass through ensure_ascii options to json.dumps in the json.tool command-line interface.

  • bpo-38634: The readline module now detects if Python is linked to libedit at runtime on all platforms. Previously, the check was only done on macOS.

  • bpo-33684: Fix json.tool failed to read a JSON file with non-ASCII characters when locale encoding is not UTF-8.

  • bpo-38698: Prevent UnboundLocalError to pop up in parse_message_id.

    parse_message_id() was improperly using a token defined inside an exception handler, which was raising UnboundLocalError on parsing an invalid value. Patch by Claudiu Popa.

  • bpo-38927: Use python -m pip instead of pip to upgrade dependencies in venv.

  • bpo-26730: Fix SpooledTemporaryFile.rollover() might corrupt the file when it is in text mode. Patch by Serhiy Storchaka.

  • bpo-38881: random.choices() now raises a ValueError when all the weights are zero.

  • bpo-38876: Raise pickle.UnpicklingError when loading an item from memo for invalid input.

    The previous code was raising a KeyError for both the Python and C implementation. This was caused by the specified index of an invalid input which did not exist in the memo structure, where the pickle stores what objects it has seen. The malformed input would have caused either a BINGET or LONG_BINGET load from the memo, leading to a KeyError as the determined index was bogus. Patch by Claudiu Popa.

  • bpo-38688: Calling func:shutil.copytree to copy a directory tree from one directory to another subdirectory resulted in an endless loop and a RecursionError. A fix was added to consume an iterator and create the list of the entries to be copied, avoiding the recursion for newly created directories. Patch by Bruno P. Kinoshita.

  • bpo-38863: Improve is_cgi() function in http.server, which enables processing the case that cgi directory is a child of another directory other than root.

  • bpo-37838: typing.get_type_hints() properly handles functions decorated with functools.wraps().

  • bpo-38870: Expose ast.unparse() as a function of the ast module that can be used to unparse an ast.AST object and produce a string with code that would produce an equivalent ast.AST object when parsed. Patch by Pablo Galindo and Batuhan Taskaya.

  • bpo-38859: AsyncMock now returns StopAsyncIteration on the exhaustion of a side_effects iterable. Since PEP-479 its Impossible to raise a StopIteration exception from a coroutine.

  • bpo-38857: AsyncMock fix for return values that are awaitable types. This also covers side_effect iterable values that happened to be awaitable, and wraps callables that return an awaitable type. Before these awaitables were being awaited instead of being returned as is.

  • bpo-38834: typing.TypedDict subclasses now track which keys are optional using the __required_keys__ and __optional_keys__ attributes, to enable runtime validation by downstream projects. Patch by Zac Hatfield-Dodds.

  • bpo-38821: Fix unhandled exceptions in argparse when internationalizing error messages for arguments with nargs set to special (non-integer) values. Patch by Federico Bond.

  • bpo-38820: Make Python compatible with OpenSSL 3.0.0. ssl.SSLSocket.getpeercert() no longer returns IPv6 addresses with a trailing new line.

  • bpo-38811: Fix an unhandled exception in pathlib when os.link() is missing. Patch by Toke Høiland-Jørgensen.

  • bpo-38686: Added support for multiple qop values in urllib.request.AbstractDigestAuthHandler.

  • bpo-38712: Add the Linux-specific signal.pidfd_send_signal() function, which allows sending a signal to a process identified by a file descriptor rather than a pid.

  • bpo-38348: Add -i and --indent (indentation level), and --no-type-comments (type comments) command line options to ast parsing tool.

  • bpo-37523: Change zipfile.ZipExtFile to raise ValueError when trying to access the underlying file object after it has been closed. This new behavior is consistent with how accessing closed files is handled in other parts of Python.

  • bpo-38045: Improve the performance of enum._decompose() in enum. Patch by hongweipeng.

  • bpo-36820: Break cycle generated when saving an exception in socket.py, codeop.py and dyld.py as they keep alive not only the exception but user objects through the __traceback__ attribute. Patch by Mario Corchero.

  • bpo-36406: Handle namespace packages in doctest. Patch by Karthikeyan Singaravelan.

  • bpo-34776: Fix dataclasses to support forward references in type annotations

  • bpo-20928: ElementTree supports recursive XInclude processing. Patch by Stefan Behnel.

  • bpo-29636: Add whitespace options for formatting JSON with the json.tool CLI. The following mutually exclusive options are now supported: --indent for setting the indent level in spaces; --tab for indenting with tabs; --no-indent for suppressing newlines; and --compact for suppressing all whitespace. The default behavior remains the same as --indent=4.

Documentation

Tests

  • bpo-38546: Fix test_ressources_gced_in_workers() of test_concurrent_futures: explicitly stop the manager to prevent leaking a child process running in the background after the test completes.

  • bpo-38546: Multiprocessing and concurrent.futures tests now stop the resource tracker process when tests complete.

  • bpo-38614: Replace hardcoded timeout constants in tests with new test.support constants: LOOPBACK_TIMEOUT, INTERNET_TIMEOUT, SHORT_TIMEOUT and LONG_TIMEOUT. It becomes easier to adjust these four timeout constants for all tests at once, rather than having to adjust every single test file.

  • bpo-38547: Fix test_pty: if the process is the session leader, closing the master file descriptor raises a SIGHUP signal: simply ignore SIGHUP when running the tests.

  • bpo-38992: Fix a test for math.fsum() that was failing due to constant folding.

  • bpo-38991: test.support: run_python_until_end(), assert_python_ok() and assert_python_failure() functions no longer strip whitespaces from stderr. Remove test.support.strip_python_stderr() function.

  • bpo-38965: Fix test_faulthandler on GCC 10. Use the “volatile” keyword in faulthandler._stack_overflow() to prevent tail call optimization on any compiler, rather than relying on compiler specific pragma.

  • bpo-38875: test_capi: trashcan tests now require the test “cpu” resource.

  • bpo-38841: Skip asyncio test_create_datagram_endpoint_existing_sock_unix on platforms lacking a functional bind() for named unix domain sockets.

  • bpo-38692: Skip the test_posix.test_pidfd_open() test if os.pidfd_open() fails with a PermissionError. This situation can happen in a Linux sandbox using a syscall whitelist which doesn’t allow the pidfd_open() syscall yet.

  • bpo-38839: Fix some unused functions in tests. Patch by Adam Johnson.

  • bpo-38669: Raise TypeError when passing target as a string with unittest.mock.patch.object().

  • bpo-37957: test.regrtest now can receive a list of test patterns to ignore (using the -i/–ignore argument) or a file with a list of patterns to ignore (using the –ignore-file argument). Patch by Pablo Galindo.

Build

  • bpo-37404: asyncio now raises TyperError when calling incompatible methods with an ssl.SSLSocket socket. Patch by Ido Michael.

  • bpo-36500: Added an optional “regen” project to the Visual Studio solution that will regenerate all grammar, tokens, and opcodes.

Windows

  • bpo-39007: Add auditing events to functions in winreg.

  • bpo-33125: Add support for building and releasing Windows ARM64 packages.

macOS

  • bpo-37931: Fixed a crash on OSX dynamic builds that occurred when re-initializing the posix module after a Py_Finalize if the environment had changed since the previous import posix. Patch by Benoît Hudson.

IDLE

  • bpo-38944: Escape key now closes IDLE completion windows. Patch by Johnny Najera.

  • bpo-38943: Fix IDLE autocomplete windows not always appearing on some systems. Patch by Johnny Najera.

  • bpo-38862: ‘Strip Trailing Whitespace’ on the Format menu removes extra newlines at the end of non-shell files.

  • bpo-38636: Fix IDLE Format menu tab toggle and file indent width. These functions (default shortcuts Alt-T and Alt-U) were mistakenly disabled in 3.7.5 and 3.8.0.

C API

  • bpo-38896: Remove PyUnicode_ClearFreeList() function: the Unicode free list has been removed in Python 3.3.

  • bpo-37340: Remove PyMethod_ClearFreeList() and PyCFunction_ClearFreeList() functions: the free lists of bound method objects have been removed.

  • bpo-38835: Exclude PyFPE_START_PROTECT() and PyFPE_END_PROTECT() macros of pyfpe.h from Py_LIMITED_API (stable API).

Python 3.9.0 alpha 1

Release date: 2019-11-19

Security

Core and Builtins

  • bpo-38631: Replace Py_FatalError() call with a regular RuntimeError exception in float.__getformat__().

  • bpo-38639: Optimized math.floor(), math.ceil() and math.trunc() for floats.

  • bpo-38640: 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.

  • bpo-38613: 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.

  • bpo-28029: "".replace("", s, n) now returns s instead of an empty string for all non-zero n. There are similar changes for bytes and bytearray objects.

  • bpo-38535: Fixed line numbers and column offsets for AST nodes for calls without arguments in decorators.

  • bpo-38525: Fix a segmentation fault when using reverse iterators of empty dict objects. Patch by Donghee Na and Inada Naoki.

  • bpo-38465: bytearray, array and mmap objects allow now to export more than 2**31 buffers at a time.

  • bpo-38469: 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.

  • bpo-38437: Activate the GC_DEBUG macro for debug builds of the interpreter (when Py_DEBUG is set). Patch by Pablo Galindo.

  • bpo-38379: 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.

  • bpo-38379: 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.

  • bpo-38392: In debug mode, 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.

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

  • bpo-38402: Check the error from the system’s underlying crypt or crypt_r.

  • bpo-37474: 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.

  • bpo-38006: 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.

  • bpo-38317: Fix warnings options priority: PyConfig.warnoptions has the highest priority, as stated in the PEP 587.

  • bpo-38310: Predict BUILD_MAP_UNPACK_WITH_CALL -> CALL_FUNCTION_EX opcode pairs in the main interpreter loop. Patch by Brandt Bucher.

  • bpo-36871: 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.

  • bpo-11410: 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.

  • bpo-38219: Optimized the dict constructor and the update() method for the case when the argument is a dict.

  • bpo-38236: Python now dumps path configuration if it fails to import the Python codecs of the filesystem and stdio encodings.

  • bpo-38013: Allow to call async_generator_athrow().throw(...) even for non-started async generator helper. It fixes annoying warning at the end of asyncio.run() call.

  • bpo-38124: Fix an off-by-one error in PyState_AddModule that could cause out-of-bounds memory access.

  • bpo-38116: The select module is now PEP-384 compliant and no longer has static state