Changelog

Python next

Release date: XXXX-XX-XX

Library

• gh-53203: Fix time.strptime() for %c, %x and %X formats in many locales that use non-ASCII digits, like Persian, Burmese, Odia and Shan.

• gh-125254: Fix a bug where ArgumentError includes the incorrect ambiguous option in argparse.

• gh-61011: Fix inheritance of nested mutually exclusive groups from parent parser in argparse.ArgumentParser. Previously, all nested mutually exclusive groups lost their connection to the group containing them and were displayed as belonging directly to the parser.

• gh-125118: Don’t copy arbitrary values to _Bool in the struct module.

• gh-125069: Fix an issue where providing a pathlib.PurePath object as an initializer argument to a second PurePath object with a different flavour resulted in arguments to the former object’s initializer being joined by the latter object’s flavour.

• gh-124969: Fix locale.nl_langinfo(locale.ALT_DIGITS). Now it returns a tuple of up to 100 strings (an empty tuple on most locales). Previously it returned the first item of that tuple or an empty string.

• gh-53203: Fix time.strptime() for %c and %x formats in many locales: Arabic, Bislama, Breton, Bodo, Kashubian, Chuvash, Estonian, French, Irish, Ge’ez, Gurajati, Manx Gaelic, Hebrew, Hindi, Chhattisgarhi, Haitian Kreyol, Japanese, Kannada, Korean, Marathi, Malay, Norwegian, Nynorsk, Punjabi, Rajasthani, Tok Pisin, Yoruba, Yue Chinese, Yau/Nungon and Chinese.

• gh-124917: Allow calling os.path.exists() and os.path.lexists() with keyword arguments on Windows. Fixes a regression in 3.12.4.

• gh-124653: Fix detection of the minimal Queue API needed by the logging module. Patch by Bénédikt Tran.

• gh-124390: Fixed AssertionError when using asyncio.staggered.staggered_race() with asyncio.eager_task_factory.

• gh-120378: Fix a crash related to an integer overflow in curses.resizeterm() and curses.resize_term().

• gh-123884: Fixed bug in itertools.tee() handling of other tee inputs (a tee in a tee). The output now has the promised n independent new iterators. Formerly, the first iterator was identical (not independent) to the input iterator. This would sometimes give surprising results.

• gh-123978: Remove broken time.thread_time() and time.thread_time_ns() on NetBSD.

• gh-117766: Always use str() to print choices in argparse.

• bpo-14074: Fix argparse metavar processing to allow positional arguments to have a tuple metavar.

IDLE

• gh-122392: Increase currently inadequate vertical spacing for the IDLE browsers (path, module, and stack) on high-resolution monitors.

Documentation

• gh-125018: The importlib.metadata documentation now includes semantic cross-reference targets for the significant documented APIs. This means intersphinx references like importlib.metadata.version() will now work as expected.

Core and Builtins

• gh-125008: Fix tokenize.untokenize() producing invalid syntax for double braces preceded by certain escape characters.

• gh-123378: Fix a crash in the __str__() method of UnicodeError objects when the UnicodeError.start and UnicodeError.end values are invalid or out-of-range. Patch by Bénédikt Tran.

C API

• gh-113601: Removed debug build assertions related to interning strings, which were falsely triggered by stable ABI extensions.

Python 3.12.7 final

Release date: 2024-10-01

Windows

• gh-123915: Ensure that Tools\msi\buildrelease.bat uses different directories for AMD64 and ARM64 builds.

• gh-117505: Fixes an issue with the Windows installer not running ensurepip in a fully isolated environment. This could cause unexpected interactions with the user site-packages.

Tests

• gh-124378: Updated test_ttk to pass with Tcl/Tk 8.6.15.

Security

• 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-116850: Fix argparse for namespaces with not directly writable dict (e.g. classes).

• gh-58573: Fix conflicts between abbreviated long options in the parent parser and subparsers in argparse.

• gh-61181: Fix support of choices with string value in argparse. Substrings of the specified string no longer considered valid values.

• gh-80259: Fix argparse support of positional arguments with nargs='?', default=argparse.SUPPRESS and specified type.

• gh-124498: Fix typing.TypeAliasType not to be generic, when type_params is an empty tuple.

• gh-124345: argparse vim supports abbreviated single-dash long options separated by = from its value.

• gh-104860: Fix disallowing abbreviation of single-dash long options in argparse with allow_abbrev=False.

• gh-63143: Fix parsing mutually exclusive arguments in argparse. Arguments with the value identical to the default value (e.g. booleans, small integers, empty or 1-character strings) are no longer considered “not present”.

• gh-72795: Positional arguments with nargs equal to '*' or argparse.REMAINDER are no longer required. This allows to use positional argument with nargs='*' and without default in mutually exclusive group and improves error message about required arguments.

• gh-59317: Fix parsing positional argument with nargs equal to '?' or '*' if it is preceded by an option and another positional argument.

• gh-53780: argparse now ignores the first "--" (double dash) between an option and command.

• gh-124217: Add RFC 9637 reserved IPv6 block 3fff::/20 in ipaddress module.

• gh-124248: Fixed potential crash when using struct to process zero-width ‘Pascal string’ fields (0p).

• gh-81691: Fix handling of multiple "--" (double dashes) in argparse. Only the first one has now been removed, all subsequent ones are now taken literally.

• gh-87041: Fix a bug in argparse where lengthy subparser argument help is incorrectly indented.

• gh-124171: Add workaround for broken fmod() implementations on Windows, that loose zero sign (e.g. fmod(-10, 1) returns 0.0). Patch by Sergey B Kirpichev.

• gh-123934: Fix unittest.mock.MagicMock reseting magic methods return values after .reset_mock(return_value=True) was called.

• gh-123935: Fix parent slots detection for dataclasses that inherit from classes with __dictoffset__.

• gh-123892: Add "_wmi" to sys.stdlib_module_names. Patch by Victor Stinner.

• gh-116810: Resolve a memory leak introduced in CPython 3.10’s ssl when the ssl.SSLSocket.session property was accessed. Speeds up read and write access to said property by no longer unnecessarily cloning session objects via serialization.

• gh-121735: When working with zip archives, importlib.resources now properly honors module-adjacent references (e.g. files(pkg.mod) and not just files(pkg)).

• gh-119004: Fix a crash in OrderedDict.__eq__ when operands are mutated during the check. Patch by Bénédikt Tran.

• bpo-44864: Do not translate user-provided strings in argparse.ArgumentParser.

IDLE

• gh-112938: Fix uninteruptable hang when Shell gets rapid continuous output.

Core and Builtins

• gh-116510: Fix a bug that can cause a crash when sub-interpreters use “basic” single-phase extension modules. Shared objects could refer to PyGC_Head nodes that had been freed as part of interpreter cleanup.

• gh-124188: Fix reading and decoding a line from the source file witn non-UTF-8 encoding for syntax errors raised in the compiler.

• gh-77894: Fix possible crash in the garbage collector when it tries to break a reference loop containing a memoryview object. Now a memoryview object can only be cleared if there are no buffers that refer it.

• gh-98442: Fix too wide source locations of the cleanup instructions of a with statement.

• gh-113993: Strings interned with sys.intern() are again garbage-collected when no longer used, as per the documentation. Strings interned with the C function PyUnicode_InternInPlace() are still immortal. Internals of the string interning mechanism have been changed. This may affect performance and identities of str objects.

C API

• gh-113993: PyUnicode_InternInPlace() no longer prevents its argument from being garbage collected.

  Several functions that take char * are now documented as possibly preventing string objects from being garbage collected; refer to their documentation for details: PyUnicode_InternFromString(), PyDict_SetItemString(), PyObject_SetAttrString(), PyObject_DelAttrString(), PyUnicode_InternFromString(), and PyModule_Add* convenience functions.

Build

• gh-124487: Windows builds now use Windows 8.1 as their API baseline (installation already required Windows 8.1).

• gh-123917: Fix the check for the crypt() function in the configure script. Patch by Paul Smith and Victor Stinner.

Python 3.12.6 final

Release date: 2024-09-06

macOS

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

Windows

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

• gh-100256: mimetypes no longer fails when it encounters an inaccessible registry key.

• gh-79846: Makes ssl.create_default_context() ignore invalid certificates in the Windows certificate store

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-101525: Skip test_gdb if the binary is relocated by BOLT. Patch by Donghee Na.

Security

• gh-123678: Upgrade libexpat to 2.6.3

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

Library

• gh-123270: Applied a more surgical fix for malformed payloads in zipfile.Path causing infinite loops (gh-122905) without breaking contents using legitimate characters.

• gh-123213: xml.etree.ElementTree.Element.extend() and Element assignment no longer hide the internal exception if an erronous generator is passed. Patch by Bar Harel.

• gh-85110: Preserve relative path in URL without netloc in urllib.parse.urlunsplit() and urllib.parse.urlunparse().

• gh-123067: Fix quadratic complexity in parsing "-quoted cookie values with backslashes by http.cookies.

• gh-122903: zipfile.Path.glob now correctly matches directories instead of silently omitting them.

• gh-122905: zipfile.Path objects now sanitize names from the zipfile.

• gh-122695: Fixed double-free when using gc.get_referents() with a freed asyncio.Future iterator.

• gh-116263: logging.handlers.RotatingFileHandler no longer rolls over empty log files.

• gh-118814: Fix the typing.TypeVar constructor when name is passed by keyword.

• gh-122478: Remove internal frames from tracebacks shown in code.InteractiveInterpreter with non-default sys.excepthook(). Save correct tracebacks in sys.last_traceback and update __traceback__ attribute of sys.last_value and sys.last_exc.

• gh-113785: csv now correctly parses numeric fields (when used with csv.QUOTE_NONNUMERIC) which start with an escape character.

• gh-112182: asyncio.futures.Future.set_exception() now transforms StopIteration into RuntimeError instead of hanging or other misbehavior. Patch contributed by Jamie Phan.

• gh-108172: webbrowser honors OS preferred browser on Linux when its desktop entry name contains the text of a known browser name.

• gh-102988: email.utils.getaddresses() and email.utils.parseaddr() now return ('', '') 2-tuples in more situations where invalid email addresses are encountered instead of potentially inaccurate values. Add optional strict parameter to these two functions: use strict=False to get the old behavior, accept malformed inputs. getattr(email.utils, 'supports_strict_parsing', False) can be use to check if the strict paramater is available. Patch by Thomas Dwyer and Victor Stinner to improve the CVE-2023-27043 fix.

• gh-99437: runpy.run_path() now decodes path-like objects, making sure __file__ and sys.argv[0] of the module being run are always strings.

IDLE

• gh-120083: Add explicit black IDLE Hovertip foreground color needed for recent macOS. Fixes Sonoma showing unreadable white on pale yellow. Patch by John Riggles.

Core and Builtins

• gh-123321: Prevent Parser/myreadline race condition from segfaulting on multi-threaded use. Patch by Bar Harel and Amit Wienner.

• gh-122982: Extend the deprecation period for bool inversion (~) by two years.

• gh-123229: Fix valgrind warning by initializing the f-string buffers to 0 in the tokenizer. Patch by Pablo Galindo

• gh-123142: Fix too-wide source location in exception tracebacks coming from broken iterables in comprehensions.

• gh-123048: Fix a bug where pattern matching code could emit a JUMP_FORWARD with no source location.

• gh-123083: Fix a potential use-after-free in STORE_ATTR_WITH_HINT.

• gh-122527: Fix a crash that occurred when a PyStructSequence was deallocated after its type’s dictionary was cleared by the GC. The type’s tp_basicsize now accounts for non-sequence fields that aren’t included in the Py_SIZE of the sequence.

• gh-93691: Fix source locations of instructions generated for with statements.

Build

• gh-123297: Propagate the value of LDFLAGS to LDCXXSHARED in sysconfig. Patch by Pablo Galindo

Python 3.12.5 final

Release date: 2024-08-06

Windows

• gh-122573: The Windows build of CPython now requires 3.10 or newer.

Tests

• gh-59022: Add tests for pkgutil.extend_path(). Patch by Andreas Stocker.

• gh-99242: os.getloadavg() may throw OSError when running regression tests under certain conditions (e.g. chroot). This error is now caught and ignored, since reporting load average is optional.

• gh-121084: Fix test_typing random leaks. Clear typing ABC caches when running tests for refleaks (-R option): call _abc_caches_clear() on typing abstract classes and their subclasses. Patch by Victor Stinner.

• gh-121160: Add a test for readline.set_history_length(). Note that this test may fail on readline libraries.

• gh-121200: Fix test_expanduser_pwd2() of test_posixpath. Call getpwnam() to get pw_dir, since it can be different than getpwall() pw_dir. Patch by Victor Stinner.

• gh-121188: When creating the JUnit XML file, regrtest now escapes characters which are invalid in XML, such as the chr(27) control character used in ANSI escape sequences. Patch by Victor Stinner.

Security

• 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>

Library

• gh-122744: Bump the version of pip bundled in ensurepip to version 24.2.

• gh-122334: Fix crash when importing ssl after the main interpreter restarts.

• gh-87320: In code.InteractiveInterpreter, handle exceptions caused by calling a non-default sys.excepthook(). Before, the exception bubbled up to the caller, ending the REPL.

• gh-122400: Handle ValueErrors raised by os.stat() in filecmp.dircmp and filecmp.cmpfiles(). Patch by Bénédikt Tran.

• gh-122311: Fix some error messages in pickle.

• gh-121650: email headers with embedded newlines are now quoted on output. The generator 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-122332: Fixed segfault with asyncio.Task.get_coro() when using an eager task factory.

• gh-122170: Handle ValueErrors raised by os.stat() in linecache. Patch by Bénédikt Tran.

• gh-121723: Make logging.config.dictConfig() accept any object implementing the Queue public API. See the queue configuration section for details. Patch by Bénédikt Tran.

• gh-82951: Serializing objects with complex __qualname__ (such as unbound methods and nested classes) by name no longer involves serializing parent objects by value in pickle protocols < 4.

• gh-120930: Fixed a bug introduced by gh-92081 that added an incorrect extra blank to encoded words occurring in wrapped headers.

• gh-121474: Fix missing sanity check for parties arg in threading.Barrier constructor. Patch by Clinton Christian (pygeek).

• gh-121025: Improve the __repr__() of functools.partialmethod. Patch by Bénédikt Tran.

• gh-121018: Fixed issues where argparse.ArgumentParser.parse_args() did not honor exit_on_error=False. Based on patch by Ben Hsing.

• gh-119614: Fix truncation of strings with embedded null characters in some internal operations in tkinter.

• gh-120910: When reading installed files from an egg, use relative_to(walk_up=True) to honor files installed outside of the installation root.

• gh-101830: Accessing the tkinter object’s string representation no longer converts the underlying Tcl object to a string on Windows.

• gh-120811: Fix possible memory leak in contextvars.Context.run().

• gh-120769: Make empty line in pdb repeats the last command even when the command is from cmdqueue.

• gh-120732: Fix name passing to unittest.mock.Mock object when using unittest.mock.create_autospec().

• gh-120495: Fix incorrect exception handling in Tab Nanny. Patch by Wulian233.

• gh-120343: Fix column offset reporting for tokens that come after multiline f-strings in the tokenize module.

• gh-119600: Fix unittest.mock.patch() to not read attributes of the target when new_callable is set. Patch by Robert Collins.

• gh-120289: Fixed the use-after-free issue in cProfile by disallowing disable() and clear() in external timers.

• gh-114053: Fix edge-case bug where typing.get_type_hints() would produce incorrect results if type parameters in a class scope were overridden by assignments in a class scope and from __future__ import annotations semantics were enabled. Patch by Alex Waygood.

• gh-114053: Fix erroneous NameError when calling inspect.get_annotations() with eval_str=True` on a class that made use of PEP 695 type parameters in a module that had from __future__ import annotations at the top of the file. Patch by Alex Waygood.

• gh-120268: Prohibit passing None to pure-Python datetime.date.fromtimestamp() to achieve consistency with C-extension implementation.

• gh-120244: Fix memory leak in re.sub() when the replacement string contains backreferences.

• gh-120211: Fix tkinter.ttk with Tcl/Tk 9.0.

• gh-71587: Fix crash in C version of datetime.datetime.strptime() when called again on the restarted interpreter.

• gh-117983: Defer the threading import in importlib.util until lazy loading is used.

• gh-119698: Fix symtable.Class.get_methods() and document its behaviour. Patch by Bénédikt Tran.

• gh-120121: Add concurrent.futures.InvalidStateError to module’s __all__.

• gh-112672: Support building tkinter with Tcl 9.0.

• gh-65454: unittest.mock.Mock.attach_mock() no longer triggers a call to a PropertyMock being attached.

• gh-81936: help() and showtopic() methods now respect a configured output argument to pydoc.Helper and not use the pager in such cases. Patch by Enrico Tröger.

• gh-119577: The DeprecationWarning emitted when testing the truth value of an xml.etree.ElementTree.Element now describes unconditionally returning True in a future version rather than raising an exception in Python 3.14.

• gh-119506: Fix io.TextIOWrapper.write() method breaks internal buffer when the method is called again during flushing internal buffer.

• gh-119189: When using the ** operator or pow() with Fraction as the base and an exponent that is not rational, a float, or a complex, the fraction is no longer converted to a float.

• gh-105623: Fix performance degradation in logging.handlers.RotatingFileHandler. Patch by Craig Robson.

• bpo-39324: Add mime type mapping for .md <-> text/markdown

IDLE

• gh-122482: Change About IDLE to direct users to discuss.python.org instead of the now unused idle-dev email and mailing list.

• gh-78889: Stop Shell freezes by blocking user access to non-method sys.stdout.shell attributes, which are all private.

• gh-120104: Fix padding in config and search dialog windows in IDLE.

Documentation

• gh-121749: Fix documentation for PyModule_AddObjectRef().

• gh-120012: Clarify the behaviours of multiprocessing.Queue.empty() and multiprocessing.SimpleQueue.empty() on closed queues. Patch by Bénédikt Tran.

Core and Builtins

• gh-122208: Dictionary watchers now only deliver the PyDict_EVENT_ADDED event when the insertion is in a known good state to succeed.

• gh-122300: Preserve AST nodes for f-string with single-element format specifiers. Patch by Pablo Galindo

• gh-122029: Emit c_call events in sys.setprofile() when a PyMethodObject pointing to a PyCFunction is called.

• gh-122026: Fix a bug that caused the tokenizer to not correctly identify mismatched parentheses inside f-strings in some situations. Patch by Pablo Galindo

• gh-121657: Improve the SyntaxError message if the user tries to use yield from outside a function.

• gh-117482: Unexpected slot wrappers are no longer created for builtin static types in subinterpreters.

• gh-121439: Allow tuples of length 20 in the freelist to be reused.

• gh-121130: Fix f-strings with debug expressions in format specifiers. Patch by Pablo Galindo

• gh-120722: Correctly set the bytecode position on return instructions within lambdas. Patch by Jelle Zijlstra.

• 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-120380: Fix Python implementation of pickle.Pickler for bytes and bytearray objects when using protocol version 5. Patch by Bénédikt Tran.

• gh-93691: Fix source locations of instructions generated for the iterator of a for statement.

• gh-120198: Fix a crash when multiple threads read and write to the same __class__ of an object concurrently.

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

• gh-119666: Fix a compiler crash in the case where two comprehensions in class scope both reference __class__.

• bpo-24766: Fix handling of doc argument to subclasses of property.

Build

• gh-120671: Fix failing configure tests due to a missing space when appending to CFLAGS.

• gh-115983: Skip building test modules that must be built as shared under WASI.

Python 3.12.4 final

Release date: 2024-06-06

Security

• 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

• gh-117233: Detect BLAKE2, SHA3, Shake, & truncated SHA512 support in the OpenSSL-ish libcrypto library at build time. This allows hashlib to be used with libraries that do not to support every algorithm that upstream OpenSSL does.

Core and Builtins

• gh-119821: Fix execution of annotation scopes within classes when globals is set to a non-dict. Patch by Jelle Zijlstra.

• gh-119311: Fix bug where names are unexpectedly mangled in the bases of generic classes.

• gh-119395: Fix bug where names appearing after a generic class are mangled as if they are in the generic class.

• gh-119213: Non-builtin modules built with argument clinic were crashing if used in a subinterpreter before the main interpreter. The objects that were causing the problem by leaking between interpreters carelessly have been fixed.

• gh-119011: Fixes type.__type_params__ to return an empty tuple instead of a descriptor.

• gh-118997: Fix _Py_ClearImmortal() assertion: use _Py_IsImmortal() to tolerate reference count lower than _Py_IMMORTAL_REFCNT. Fix the assertion for the stable ABI, when a C extension is built with Python 3.11 or lower. Patch by Victor Stinner.

• gh-118513: Fix incorrect UnboundLocalError when two comprehensions in the same function both reference the same name, and in one comprehension the name is bound while in the other it’s an implicit global.

• gh-118164: Break a loop between the Python implementation of the decimal module and the Python code for integer to string conversion. Also optimize integer to string conversion for values in the range from 9_000 to 135_000 decimal digits.

• gh-118272: Fix bug where generator.close does not free the generator frame’s locals.

• gh-116767: Fix crash in compiler on ‘async with’ that has many context managers.

• gh-117894: Prevent agen.aclose() objects being re-used after .throw().

• gh-117881: prevent concurrent access to an async generator via athrow().throw() or asend().throw()

• gh-115874: Fixed a possible segfault during garbage collection of _asyncio.FutureIter objects

Library

• gh-119819: Fix regression to allow logging configuration with multiprocessing queue types.

• gh-89727: Fix issue with shutil.rmtree() where a RecursionError is raised on deep directory trees.

• gh-89727: Partially fix issue with shutil.rmtree() where a RecursionError is raised on deep directory trees. A recursion error is no longer raised when rmtree.avoids_symlink_attacks is false.

• gh-119118: Fix performance regression in the tokenize module by caching the line token attribute and calculating the column offset more efficiently.

• gh-89727: Fix issue with os.fwalk() where a RecursionError was raised on deep directory trees by adjusting the implementation to be iterative instead of recursive.

• gh-118263: Speed up os.path.normpath() with a direct C call.

• gh-113892: Now, the method sock_connect of asyncio.ProactorEventLoop raises a ValueError if given socket is not in non-blocking mode, as well as in other loop implementations.

• gh-118507: Fix os.path.isfile() on Windows for pipes.

• gh-119174: Fix high DPI causes turtledemo(turtle-graphics examples) windows blurry Patch by Wulian233 and Terry Jan Reedy

• gh-118643: Fix an AttributeError in the email module when re-fold a long address list. Also fix more cases of incorrect encoding of the address separator in the address list.

• gh-58933: Make pdb return to caller frame correctly when f_trace of the caller frame is not set

• gh-118868: Fixed issue where kwargs were no longer passed to the logging handler QueueHandler

• gh-118164: The Python implementation of the decimal module could appear to hang in relatively small power cases (like 2**117) if context precision was set to a very high value. A different method to check for exactly representable results is used now that doesn’t rely on computing 10**precision (which could be effectively too large to compute).

• gh-118404: Fix inspect.signature() for non-comparable callables.

• gh-118314: Fix an edge case in binascii.a2b_base64() strict mode, where excessive padding is not detected when no padding is necessary.

• gh-118042: Fix an unraisable exception in telnetlib.Telnet.__del__() when the __init__() method was not called.

• gh-118221: Fix a bug where sqlite3.iterdump() could fail if a custom row factory was used. Patch by Erlend Aasland.

• gh-118013: Fix regression introduced in gh-103193 that meant that calling inspect.getattr_static() on an instance would cause a strong reference to that instance’s class to persist in an internal cache in the inspect module. This caused unexpected memory consumption if the class was dynamically created, the class held strong references to other objects which took up a significant amount of memory, and the cache contained the sole strong reference to the class. The fix for the regression leads to a slowdown in getattr_static(), but the function should still be significantly faster than it was in Python 3.11. Patch by Alex Waygood.

• gh-90848: Fixed unittest.mock.create_autospec() to configure parent mock with keyword arguments.

• gh-118168: Fix incorrect argument substitution when typing.Unpack is used with the builtin tuple. typing.Unpack now raises TypeError when used with certain invalid types. Patch by Jelle Zijlstra.

• gh-118033: Fix dataclasses.dataclass() not creating a __weakref__ slot when subclassing typing.Generic.

• gh-117535: Do not try to get the source line for made up file name “sys” in warnings.

• gh-114053: Fix erroneous NameError when calling typing.get_type_hints() on a class that made use of PEP 695 type parameters in a module that had from __future__ import annotations at the top of the file. Patch by Alex Waygood.

• gh-117995: Don’t raise DeprecationWarning when a sequence of parameters is used to bind indexed, nameless placeholders. See also gh-100668.

• gh-80361: Fix TypeError in email.message.Message.get_payload() when the charset is RFC 2231 encoded.

• gh-86650: Fix IndexError when parse some emails with invalid Message-ID (including one-off addresses generated by Microsoft Outlook).

• gh-117691: Improve the error messages emitted by tarfile deprecation warnings relating to PEP 706. If a filter argument is not provided to extract() or extractall, the deprecation warning now points to the line in the user’s code where the relevant function was called. Patch by Alex Waygood.

• gh-77102: site module now parses .pth file with UTF-8 first, and locale encoding if UnicodeDecodeError happened. It supported only locale encoding before.

• gh-117692: Fixes a bug when doctest.DocTestFinder was failing on wrapped builtin_function_or_method.

• gh-117566: ipaddress.IPv6Address.is_loopback() will now return True for IPv4-mapped loopback addresses, i.e. addresses in the ::ffff:127.0.0.0/104 address space.

• gh-117503: Fix support of non-ASCII user names in bytes paths in os.path.expanduser() on Posix.

• gh-117313: Only treat '\n', '\r' and '\r\n' as line separators in re-folding the email messages. Preserve control characters '\v', '\f', '\x1c', '\x1d' and '\x1e' and Unicode line separators '\x85', '\u2028' and '\u2029' as is.

• gh-113171: Fixed various false positives and false negatives in

  • ipaddress.IPv4Address.is_private (see these docs for details)

  • ipaddress.IPv4Address.is_global

  • ipaddress.IPv6Address.is_private

  • ipaddress.IPv6Address.is_global

  Also in the corresponding ipaddress.IPv4Network and ipaddress.IPv6Network attributes.

• gh-103956: Fix lack of newline characters in trace module output when line tracing is enabled but source code line for current frame is not available.

• gh-92081: Fix missing spaces in email headers when the spaces are mixed with encoded 8-bit characters.

• gh-103194: Prepare Tkinter for C API changes in Tcl 8.7/9.0 to avoid _tkinter.Tcl_Obj being unexpectedly returned instead of bool, str, bytearray, or int.

• gh-87106: Fixed handling in inspect.Signature.bind() of keyword arguments having the same name as positional-only arguments when a variadic keyword argument (e.g. **kwargs) is present.

• bpo-45767: Fix integer conversion in os.major(), os.minor(), and os.makedev(). Support device numbers larger than 2**63-1. Support non-existent device number (NODEV).

• bpo-40943: Fix several IndexError when parse emails with truncated Message-ID, address, routes, etc, e.g. example@.

• bpo-30988: Fix parsing of emails with invalid address headers having a leading or trailing dot. Patch by tsufeki.

• gh-67693: Fix urllib.parse.urlunparse() and urllib.parse.urlunsplit() for URIs with path starting with multiple slashes and no authority. Based on patch by Ashwin Ramaswami.

• bpo-15010: unittest.TestLoader.discover() now saves the original value of unittest.TestLoader._top_level_dir and restores it at the end of the call.

Documentation

• gh-117928: The minimum Sphinx version required for the documentation is now 6.2.1.

• gh-91565: Changes to documentation files and config outputs to reflect the new location for reporting bugs - i.e. GitHub rather than bugs.python.org.

Tests

• gh-119050: regrtest test runner: Add XML support to the refleak checker (-R option). Patch by Victor Stinner.

Windows

• gh-119690: Adds Unicode support and fixes audit events for _winapi.CreateNamedPipe.

• gh-119070: Fixes py.exe handling of shebangs like /usr/bin/env python3.12, which were previously interpreted as python3.exe instead of python3.12.exe.

• gh-118347: Fixes launcher updates not being installed.

• gh-115009: Update Windows installer to use SQLite 3.45.3.

• gh-90329: Suppress the warning displayed on virtual environment creation when the requested and created paths differ only by a short (8.3 style) name. Warnings will continue to be shown if a junction or symlink in the path caused the venv to be created in a different location than originally requested.

macOS

• gh-115009: Update macOS installer to use SQLite 3.45.3.

• gh-116145: Update macOS installer to Tcl/Tk 8.6.14.

IDLE

• bpo-34774: Use user-selected color theme for Help => IDLE Doc.

C API

• gh-119585: Fix crash when a thread state that was created by PyGILState_Ensure() calls a destructor that during PyThreadState_Clear() that calls back into PyGILState_Ensure() and PyGILState_Release(). This might occur when in the free-threaded build or when using thread-local variables whose destructors call PyGILState_Ensure().

• gh-117534: Improve validation logic in the C implementation of datetime.fromisoformat() to better handle invalid years. Patch by Vlad Efanov.

Python 3.12.3 final

Release date: 2024-04-09

Security

• gh-115398: Allow controlling Expat >=2.6.0 reparse deferral (CVE 2023-52425) by adding five new methods:

  • xml.etree.ElementTree.XMLParser.flush()

  • xml.etree.ElementTree.XMLPullParser.flush()

  • xml.parsers.expat.xmlparser.GetReparseDeferralEnabled()

  • xml.parsers.expat.xmlparser.SetReparseDeferralEnabled()

  • xml.sax.expatreader.ExpatParser.flush()

• gh-115399: Update bundled libexpat to 2.6.0

• gh-115243: Fix possible crashes in collections.deque.index() when the deque is concurrently modified.

• gh-114572: ssl.SSLContext.cert_store_stats() and ssl.SSLContext.get_ca_certs() now correctly lock access to the certificate store, when the ssl.SSLContext is shared across multiple threads.

Core and Builtins

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

• gh-99108: Updated the hashlib built-in HACL* project C code from upstream that we use for many implementations when they are not present via OpenSSL in a given build. This also avoids the rare potential for a C symbol name one definition rule linking issue.

• gh-116735: For INSTRUMENTED_CALL_FUNCTION_EX, set arg0 to sys.monitoring.MISSING instead of None for CALL event.

• gh-113964: Starting new threads and process creation through os.fork() are now only prevented once all non-daemon threads exit.

• gh-116604: Respect the status of the garbage collector when indirect calls are made via PyErr_CheckSignals() and the evaluation breaker. Patch by Pablo Galindo

• gh-116626: Ensure INSTRUMENTED_CALL_FUNCTION_EX always emits CALL

• 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-115154: Fix a bug that was causing the tokenize.untokenize() function to handle unicode named literals incorrectly. Patch by Pablo Galindo

• gh-114828: Fix compilation crashes in uncommon code examples using super() inside a comprehension in a class body.

• 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-112215: Change the C recursion limits to more closely reflect the underlying platform limits.

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

Library

• gh-117467: Preserve mailbox ownership when rewriting in mailbox.mbox.flush(). Patch by Tony Mountifield.

• 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-116040: [Enum] fix by-value calls when second value is falsey; e.g. Cardinal(1, 0)

• 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-112364: Fixed ast.unparse() to handle format_spec with ", ' or \\. Patched by Frank Hoffmann.

• gh-111358: Fix a bug in asyncio.BaseEventLoop.shutdown_default_executor() to ensure the timeout passed to the coroutine behaves as expected.

• 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-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-114071: Support tuple subclasses using auto() for enum member value.

• 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

• gh-115399: Document CVE 2023-52425 of Expat <2.6.0 under “XML vulnerabilities”.

• gh-115233: Fix an example for LoggerAdapter in the Logging Cookbook.

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-116333: Tests of TLS related things (error codes, etc) were updated to be more lenient about specific error message strings and behaviors as seen in the BoringSSL and AWS-LC forks of OpenSSL.

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

• gh-112536: Add –tsan to test.regrtest for running TSAN tests in reasonable execution times. Patch by Donghee Na.

• gh-116307: Added import helper isolated_modules as CleanImport does not remove modules imported during the context. Use it in importlib.resources tests to avoid leaving mod around to impede importlib.metadata tests.

• 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.

Build

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

• gh-116117: Backport libb2’s PR #42 to fix compiling CPython on 32-bit Windows with clang-cl.

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

• gh-112536: Add support for thread sanitizer (TSAN)

Windows

• gh-117267: Ensure DirEntry.stat().st_ctime behaves consistently with os.stat() during the deprecation period of st_ctime by containing the same value as st_birthtime. After the deprecation period, st_ctime will be the metadata change time (or unavailable through DirEntry), and only st_birthtime will contain the creation time.

• 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-115049: Fixes py.exe launcher failing when run as users without user profiles.

• 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.

• gh-116869: Make the C API compatible with -Werror=declaration-after-statement compiler flag again. Patch by Victor Stinner.

Python 3.12.2 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-113703: Fix a regression in the codeop module that was causing it to incorrectly identify incomplete f-strings. Patch by Pablo Galindo

• 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-113297: Fix segfault in the compiler on with statement with 19 context managers.

• 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-112943: Correctly compute end column offsets for multiline tokens in the tokenize module. Patch by Pablo Galindo

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

• 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-113267: Revert changes in gh-106584 which made calls of TestResult methods startTest() and stopTest() unbalanced.

• 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-114328: The tty.setcbreak() and new tty.cfmakecbreak() no longer clears the terminal input ICRLF flag. This fixes a regression introduced in 3.12 that no longer matched how OSes define cbreak mode in their stty(1) manual pages.

• 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-114149: Enum: correctly handle tuple subclasses in custom __new__.

• 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-113661: unittest runner: Don’t exit 5 if tests were skipped. The intention of exiting 5 was to detect issues where the test suite wasn’t discovered at all. If we skipped tests, it was correctly discovered.

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

• gh-112932: Restore the ability for zipfile to extractall from zip files with a “/” directory entry in them as is commonly added to zips by some wiki or bug tracker data exporters.

• 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-111784: Fix segfaults in the _elementtree module. Fix first segfault during deallocation of _elementtree.XMLParser instances by keeping strong reference to pyexpat module in module state for capsule lifetime. Fix second segfault which happens in the same deallocation process by keeping strong reference to _elementtree module in XMLParser structure for _elementtree module lifetime.

• gh-113407: Fix import of unittest.mock when CPython is built without docstrings.

• gh-113320: Fix regression in Python 3.12 where Protocol classes that were not marked as runtime-checkable would be unnecessarily introspected, potentially causing exceptions to be raised if the protocol had problematic members. Patch by Alex Waygood.

• 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-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-112343: Improve handling of pdb convenience variables to avoid replacing string contents.

• gh-111615: Fix a regression caused by a fix to gh-93162 whereby you couldn’t configure a QueueHandler without specifying handlers.

• gh-111049: Fix crash during garbage collection of the io.BytesIO buffer object.

• 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-114440: On Windows, closing the connection writer when cleaning up a broken multiprocessing.Queue queue is now done for all queues, rather than only in concurrent.futures manager thread. This can prevent a deadlock when a multiprocessing worker process terminates without cleaning up. This completes the backport of patches by Victor Stinner and Serhiy Storchaka.

• 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-106233: Fix stacklevel in InvalidTZPathWarning during zoneinfo module import.

• 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.

• 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-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-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.

• gh-112867: Fix the build for the case that WITH_PYMALLOC_RADIX_TREE=0 set.

• 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-111877: os.stat() calls were returning incorrect time values for files that could not be accessed directly.

• 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-110459: Running configure ... --with-openssl-rpath=X/Y/Z no longer fails to detect OpenSSL on macOS.

• 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-108269: Set CFBundleAllowMixedLocalizations to true in the Info.plist for the framework, embedded Python.app and IDLE.app with framework installs on macOS. This allows applications to pick up the user’s preferred locale when that’s different from english.

• 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-110820: Make sure the preprocessor definitions for ALIGNOF_MAX_ALIGN_T, SIZEOF_LONG_DOUBLE and HAVE_GCC_ASM_FOR_X64 are correct for Universal 2 builds on macOS.

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 3.12.1 final

Release date: 2023-12-07

Core and Builtins

• gh-112125: Fix None.__ne__(None) returning NotImplemented instead of False

• 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-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-112356: Stopped erroneously deleting a LOAD_NULL bytecode instruction when optimized twice.

• gh-111058: Change coro.cr_frame/gen.gi_frame to return None after the coroutine/generator has been closed. This fixes a bug where getcoroutinestate() and getgeneratorstate() return the wrong state for a closed coroutine/generator.

• 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-112367: Avoid undefined behaviour when using the perf trampolines by not freeing the code arenas until shutdown. Patch by Pablo Galindo

• gh-112243: Don’t include comments in f-string debug expressions. Patch by Pablo Galindo

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

• gh-111654: Fix runtime crash when some error happens in opcode LOAD_FROM_DICT_OR_DEREF.

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

• gh-110938: Fix error messages for indented blocks with functions and classes with generic type parameters. Patch by Pablo Galindo

• gh-109894: Fixed crash due to improperly initialized static MemoryError in subinterpreter.

• gh-110782: Fix crash when typing.TypeVar is constructed with a keyword argument. Patch by Jelle Zijlstra.

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

• gh-110543: Fix regression in Python 3.12 where types.CodeType.replace() would produce a broken code object if called on a module or class code object that contains a comprehension. Patch by Jelle Zijlstra.

• gh-110514: Add PY_THROW to sys.setprofile() events

• gh-110455: Guard assert(tstate->thread_id > 0) with #ifndef HAVE_PTHREAD_STUBS. This allows for for pydebug builds to work under WASI which (currently) lacks thread support.

• gh-110259: Correctly identify the format spec in f-strings (with single or triple quotes) that have multiple lines in the expression part and include a formatting spec. Patch by Pablo Galindo

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

• gh-109889: Fix the compiler’s redundant NOP detection algorithm to skip over NOPs with no line number when looking for the next instruction’s lineno.

• gh-109853: sys.path[0] is now set correctly for subinterpreters.

• gh-105716: Subinterpreters now correctly handle the case where they have threads running in the background. Before, such threads would interfere with cleaning up and destroying them, as well as prevent running another script.

• gh-109793: The main thread no longer exits prematurely when a subinterpreter is cleaned up during runtime finalization. The bug was a problem particularly because, when triggered, the Python process would always return with a 0 exitcode, even if it failed.

• gh-109596: Fix some tokens in the grammar that were incorrectly marked as soft keywords. Also fix some repeated rule names and ensure that repeated rules are not allowed. Patch by Pablo Galindo

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

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

• 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-109052: Use the base opcode when comparing code objects to avoid interference from instrumentation

• 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-106931: Statically allocated string objects are now interned globally instead of per-interpreter. This fixes a situation where such a string would only be interned in a single interpreter. Normal string objects are unaffected.

Library

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

• gh-112645: Remove deprecation error on passing onerror to shutil.rmtree().

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

• gh-112334: Fixed a performance regression in 3.12’s subprocess on Linux where it would no longer use the fast-path vfork() system call when it should have due to a logic bug, instead always falling back to the safe but slower fork().

  Also fixed a related 3.12 security regression: If a value of extra_groups=[] was passed to subprocess.Popen or related APIs, the underlying setgroups(0, NULL) system call to clear the groups list would not be made in the child process prior to exec(). This has been assigned CVE 2023-6507.

  This was identified via code inspection in the process of fixing the first bug.

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

• gh-112578: Fix a spurious RuntimeWarning when executing the zipfile module.

• 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-112414: Fix regression in Python 3.12 where calling repr() on a module that had been imported using a custom loader could fail with AttributeError. Patch by Alex Waygood.

• gh-112358: Revert change to struct.Struct initialization that broke some cases of subclassing.

• 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-111460: curses: restore wide character support (including curses.unget_wch() and get_wch()) on macOS, which was unavailable due to a regression in Python 3.12.

• gh-103791: contextlib.suppress now supports suppressing exceptions raised as part of a BaseExceptionGroup, in addition to the recent support for ExceptionGroup.

• 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-111342: Fixed typo in math.sumprod().

• 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-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-79033: Another attempt at fixing asyncio.Server.wait_closed(). It now blocks until both conditions are true: the server is closed, and there are no more active connections. (This means that in some cases where in 3.12.0 this function would incorrectly have returned immediately, it will now block; in particular, when there are no active connections but the server hasn’t been closed yet.)

• gh-111295: Fix time not checking for errors when initializing.

• gh-111253: Add error checking during _socket module init.

• 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-110488: Fix a couple of issues in pathlib.PurePath.with_name(): a single dot was incorrectly considered a valid name, and in PureWindowsPath, a name with an NTFS alternate data stream, like a:b, was incorrectly considered invalid.

• gh-110392: Fix tty.setraw() and tty.setcbreak(): previously they returned partially modified list of the original tty attributes. tty.cfmakeraw() and tty.cfmakecbreak() now make a copy of the list of special characters before modifying it.

• 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-110395: Ensure that select.kqueue() objects correctly appear as closed in forked children, to prevent operations on an invalid file descriptor.

• 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-109653: Fix a Python 3.12 regression in the import time of random. Patch by Alex Waygood.

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

• 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-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-109818: Fix reprlib.recursive_repr() not copying __type_params__ from decorated function.

• gh-109047: concurrent.futures: The executor manager thread now catches exceptions when adding an item to the call queue. During Python finalization, creating a new thread can now raise RuntimeError. Catch the exception and call terminate_broken() in this case. Patch by Victor Stinner.

• gh-109782: Ensure the signature of os.path.isdir() is identical on all platforms. Patch by Amin Alaee.

• gh-109590: shutil.which() will prefer files with an extension in PATHEXT if the given mode includes os.X_OK on win32. If no PATHEXT match is found, a file without an extension in PATHEXT can be returned. This change will have shutil.which() act more similarly to previous behavior in Python 3.11.

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

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

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

• gh-106584: Fix exit code for unittest if all tests are skipped. Patch by Egor Eliseev.

• gh-102956: Fix returning of empty byte strings after seek in zipfile module

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

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

• 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-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-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.

Documentation

• gh-111699: Relocate smtpd deprecation notice to its own section rather than under locale in What’s New in Python 3.12 document

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

Tests

• 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-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-111165: Remove no longer used functions run_unittest() and run_doctest() 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-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-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-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-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-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-109580: Skip test_perf_profiler if Python is built with ASAN, MSAN or UBSAN sanitizer. Python does crash randomly in this test on such build. 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-112088: Add Tools/build/regen-configure.sh script to regenerate the configure with an Ubuntu container image. The quay.io/tiran/cpython_autoconf:271 container image (tiran/cpython_autoconf) is no longer used. Patch by Victor Stinner.

• gh-111046: For wasi-threads, memory is now exported to fix compatibility issues with some wasm runtimes.

• 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-111856: Fixes fstat() on file systems that do not support file ID requests. This includes FAT32 and exFAT.

• gh-111293: Fix os.DirEntry.inode dropping higher 64 bits of a file id on some filesystems on 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-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.

• 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.

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

• gh-106560: Fix redundant declarations in the public C API. Declare PyBool_Type and PyLong_Type only once. Patch by Victor Stinner.

• gh-112438: Fix support of format units “es”, “et”, “es#”, and “et#” in nested tuples in PyArg_ParseTuple()-like functions.

• gh-109521: PyImport_GetImporter() now sets RuntimeError if it fails to get sys.path_hooks or sys.path_importer_cache or they are not list and dict correspondingly. Previously it could return NULL without setting error in obscure cases, crash or raise SystemError if these attributes have wrong type.

Python 3.12.0 final

Release date: 2023-10-02

Core and Builtins

• gh-109823: Fix bug where compiler does not adjust labels when removing an empty basic block which is a jump target.

• gh-109719: Fix missing jump target labels when compiler reorders cold/warm blocks.

• gh-109627: Fix bug where the compiler does not assign a new jump target label to a duplicated small exit block.

Library

• gh-110045: Update the symtable module to support the new scopes introduced by PEP 695.

Documentation

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

Windows

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

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 3.12.0 release candidate 3

Release date: 2023-09-18

Core and Builtins

• gh-109496: On a Python built in debug mode, Py_DECREF() now calls _Py_NegativeRefcount() if the object is a dangling pointer to deallocated memory: memory filled with 0xDD “dead byte” by the debug hook on memory allocators. The fix is to check the reference count before checking for _Py_IsImmortal(). Patch by Victor Stinner.

• gh-109371: Deopted instructions correctly for tool initialization and modified the incorrect assertion in instrumentation, when a previous tool already sets INSTRUCTION events

• gh-105658: Fix bug where the line trace of an except block ending with a conditional includes an excess event with the line of the conditional expression.

• gh-109219: Fix compiling type param scopes that use a name which is also free in an inner scope.

• gh-109341: Fix crash when compiling an invalid AST involving a ast.TypeAlias.

• gh-109195: Fix source location for the LOAD_* instruction preceding a LOAD_SUPER_ATTR to load the super global (or shadowing variable) so that it encompasses only the name super and not the following parentheses.

• gh-109118: Disallow nested scopes (lambdas, generator expressions, and comprehensions) within PEP 695 annotation scopes that are nested within classes.

• gh-109114: Relax the detection of the error message for invalid lambdas inside f-strings to not search for arbitrary replacement fields to avoid false positives. Patch by Pablo Galindo

• gh-109118: Fix interpreter crash when a NameError is raised inside the type parameters of a generic class.

• gh-108976: Fix crash that occurs after de-instrumenting a code object in a monitoring callback.

• gh-108732: Make iteration variables of module- and class-scoped comprehensions visible to pdb and other tools that use frame.f_locals again.

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

Library

• gh-108682: Enum: require names=() or type=... to create an empty enum using the functional syntax.

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

Documentation

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

Tests

• 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-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-108834: Add --fail-rerun option option to regrtest: if a test failed when then passed when rerun in verbose mode, exit the process with exit code 2 (error), instead of exit code 0 (success). Patch by Victor Stinner.

• gh-108834: Rename regrtest --verbose2 option (-w) to --rerun. Keep --verbose2 as a deprecated alias. Patch by Victor Stinner.

• gh-108834: When regrtest reruns failed tests in verbose mode (./python -m test --rerun), tests are now rerun in fresh worker processes rather than being executed in the main process. If a test does crash or is killed by a timeout, the main process can detect and handle the killed worker process. Tests are rerun in parallel if the -jN option is used to run tests in parallel. Patch by Victor Stinner.

• gh-103186: Suppress and assert expected RuntimeWarnings in test_sys_settrace.py

Build

• 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.

Python 3.12.0 release candidate 2

Release date: 2023-09-05

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.

• gh-107774: PEP 669 specifies that sys.monitoring.register_callback will generate an audit event. Pre-releases of Python 3.12 did not generate the audit event. This is now fixed.

Core and Builtins

• 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.

• gh-108654: Restore locals shadowed by an inlined comprehension if the comprehension raises an exception.

• gh-108487: Change an assert that would cause a spurious crash in a devious case that should only trigger deoptimization.

• gh-106176: Use a WeakValueDictionary to track the lists containing the modules each thread is currently importing. This helps avoid a reference leak from keeping the list around longer than necessary. Weakrefs are used as GC can’t interrupt the cleanup.

• gh-107901: Fix missing line number on JUMP_BACKWARD at the end of a for loop.

• gh-108390: Raise an exception when setting a non-local event (RAISE, EXCEPTION_HANDLED, etc.) in sys.monitoring.set_local_events.

  Fixes crash when tracing in recursive calls to Python classes.

• gh-91051: Fix abort / segfault when using all eight type watcher slots, on platforms where char is signed by default.

• gh-107724: In pre-release versions of 3.12, up to rc1, the sys.monitoring callback function for the PY_THROW event was missing the third, exception argument. That is now fixed.

• gh-107080: Trace refs builds (--with-trace-refs) were crashing when used with isolated subinterpreters. The problematic global state has been isolated to each interpreter. Other fixing the crashes, this change does not affect users.

• 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.

Library

• gh-108469: ast.unparse() now supports new f-string syntax introduced in Python 3.12. Note that the f-string quotes are reselected for simplicity under the new syntax. (Patch by Steven Sun)

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

• gh-108295: Fix crashes related to use of weakrefs on typing.TypeVar.

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

• gh-108111: Fix a regression introduced in gh-101251 for 3.12, resulting in an incorrect offset calculation in gzip.GzipFile.seek().

• 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-108083: Fix bugs in the constructor of sqlite3.Connection and sqlite3.Connection.close() where exceptions could be leaked. Patch by Erlend E. Aasland.

• 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-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-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-107805: Fix signatures of module-level generated functions in turtle.

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

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

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

• 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.

Documentation

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

Tests

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

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

• gh-107178: Add the C API test for functions in the Mapping Protocol, the Sequence Protocol and some functions in the Object Protocol.

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

Windows

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

• 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 and truncating by the null character in _winapi.LCMapStringEx() which affects ntpath.normcase().

macOS

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

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.

C API

• gh-107916: C API functions PyErr_SetFromErrnoWithFilename(), PyErr_SetExcFromWindowsErrWithFilename() and PyErr_SetFromWindowsErrWithFilename() save now the error code before calling PyUnicode_DecodeFSDefault().

• gh-107915: Such C API functions as PyErr_SetString(), PyErr_Format(), PyErr_SetFromErrnoWithFilename() and many others no longer crash or ignore errors if it failed to format the error message or decode the filename. Instead, they keep a corresponding error.

• gh-107810: Improve DeprecationWarning for uses of PyType_Spec with metaclasses that have custom tp_new.

Python 3.12.0 release candidate 1

Release date: 2023-08-05

Security

• gh-102988: Reverted the email.utils security improvement change released in 3.12beta4 that unintentionally caused email.utils.getaddresses to fail to parse email addresses with a comma in the quoted name field. See gh-106669.

• gh-102509: Start initializing ob_digit during creation of PyLongObject objects. Patch by Illia Volochii.

Core and Builtins

• gh-107263: Increase C recursion limit for functions other than the main interpreter from 800 to 1500. This should allow functions like list.__repr__ and json.dumps to handle all the inputs that they could prior to 3.12

• 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-106898: Add the exception as the third argument to PY_UNIND callbacks in sys.monitoring. This makes the PY_UNWIND callback consistent with the other exception hanlding callbacks.

• gh-106895: Raise a ValueError when a monitoring callback funtion returns DISABLE for events that cannot be disabled locally.

• gh-106897: Add a RERAISE event to sys.monitoring, which occurs when an exception is reraised, either explicitly by a plain raise statement, or implicitly in an except or finally block.

• gh-104621: Unsupported modules now always fail to be imported.

• gh-106917: Fix classmethod-style super() method calls (i.e., where the second argument to super(), or the implied second argument drawn from self/cls in the case of zero-arg super, is a type) when the target of the call is not a classmethod.

• gh-105699: Python no longer crashes due an infrequent race when initialzing per-interpreter interned strings. The crash would manifest when the interpreter was finalized.

• gh-105699: Python no longer crashes due to an infrequent race in setting Py_FileSystemDefaultEncoding and Py_FileSystemDefaultEncodeErrors (both deprecated), when simultaneously initializing two isolated subinterpreters. Now they are only set during runtime initialization.

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

Library

• 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-107576: Fix types.get_original_bases() to only return __orig_bases__ if it is present on cls directly. Patch by James Hilton-Balfe.

• gh-46376: Prevent memory leak and use-after-free when using pointers to pointers with ctypes

• 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-105002: Fix invalid result from PurePath.relative_to() method when attempting to walk a “..” segment in other with walk_up enabled. A ValueError exception is now raised in this case.

• 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 bugs in zipfile.Path, including: in Path.match, Windows separators are no longer honored (and never were meant to be); Fixed name/suffix/suffixes/stem operations when no filename is present and the Path is not at the root of the zipfile; Reworked glob for performance and more correct matching behavior.

• 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-106403: Instances of typing.TypeVar, typing.ParamSpec, typing.ParamSpecArgs, typing.ParamSpecKwargs, and typing.TypeVarTuple once again support weak references, fixing a regression introduced in Python 3.12.0 beta 1. Patch by Jelle Zijlstra.

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

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

• gh-105626: Change the default return value of http.client.HTTPConnection.get_proxy_response_headers() to be None and not {}.

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

Documentation

• gh-107305: Add documentation for PyInterpreterConfig and Py_NewInterpreterFromConfig(). Also clarify some of the nearby docs relative to per-interpreter GIL.

• gh-107008: Document the curses module variables LINES and COLS.

• gh-106948: Add a number of standard external names to nitpick_ignore.

• gh-54738: Add documentation on how to localize the argparse module.

Tests

• 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-106714: test_capi: Fix test_no_FatalError_infinite_loop() to no longer write a coredump, by using test.support.SuppressCrashReport. Patch by Victor Stinner.

• gh-104090: Avoid creating a reference to the test object in collectedDurations().

• gh-106752: Moved tests for zipfile.Path into Lib/test/test_zipfile/_path. Made zipfile._path a package.

Build

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

• gh-106962: Detect MPI compilers in configure.

• gh-101538: Add experimental wasi-threads support. Patch by Takashi Yamamoto.

Windows

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

macOS

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

Tools/Demos

• 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.

• gh-103186: freeze now fetches CONFIG_ARGS from the original CPython instance the Makefile uses to call utility scripts. Patch by Ijtaba Hussain.

C API

• gh-107226: PyModule_AddObjectRef() is now only available in the limited API version 3.10 or later.

Python 3.12.0 beta 4

Release date: 2023-07-11

Security

• gh-102988: CVE 2023-27043: Prevent email.utils.parseaddr() and email.utils.getaddresses() from returning the realname portion of an invalid RFC2822 email header in the email address portion of the 2-tuple returned after being parsed by email._parseaddr.AddressList.

Core and Builtins

• gh-106396: When the format specification of an f-string expression is empty, the parser now generates an empty ast.JoinedStr node for it instead of an one-element ast.JoinedStr with an empty string ast.Constant.

• gh-106145: Make end_lineno and end_col_offset required on type_param ast nodes.

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

• gh-98931: Ensure custom SyntaxError error messages are raised for invalid imports with multiple targets. Patch by Pablo Galindo

• gh-105908: Fixed bug where gh-99111 breaks future import barry_as_FLUFL in the Python REPL.

• gh-105340: Include the comprehension iteration variable in locals() inside a module- or class-scope comprehension.

• gh-105486: Change the repr of ParamSpec list of args in types.GenericAlias.

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

Library

• gh-106524: Fix crash in _sre.template() with templates containing invalid group indices.

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

• gh-106503: Fix ref cycle in asyncio._SelectorSocketTransport by removing _write_ready in close.

• 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-106292: Check for an instance-dict cached value in the __get__() method of functools.cached_property(). This better matches the pre-3.12 behavior and improves compatibility for users subclassing functools.cached_property() and adding a __set__() method.

• gh-106330: Fix incorrect matching of empty paths in pathlib.PurePath.match(). This bug was introduced in Python 3.12.0 beta 1.

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

• gh-106152: Added PY_THROW event hook for cProfile for generators

• gh-106075: Added asyncio.taskgroups.__all__ to asyncio.__all__ for export in star imports.

• gh-105987: Fix crash due to improper reference counting in asyncio eager task factory internal routines.

• gh-105974: Fix bug where a typing.Protocol class that had one or more non-callable members would raise TypeError when issubclass() was called against it, even if it defined a custom __subclasshook__ method. The behaviour in Python 3.11 and lower – which has now been restored – was not to raise TypeError in these situations if a custom __subclasshook__ method was defined. Patch by Alex Waygood.

• gh-96145: Reverted addition of json.AttrDict.

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

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

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

Documentation

• gh-106232: Make timeit doc command lines compatible with Windows by using double quotes for arguments. This works on linux and macOS also.

Tests

• 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-106118: Fix compilation for platforms without O_CLOEXEC. The issue was introduced with Python 3.12b1 in gh-103295. Patch by Erlend Aasland.

• 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.

Tools/Demos

• gh-106359: Argument Clinic now explicitly forbids “kwarg splats” in function calls used as annotations.

C API

• gh-105227: The new PyType_GetDict() provides the dictionary for the given type object that is normally exposed by cls.__dict__. Normally it’s sufficient to use tp_dict, but for the static builtin types tp_dict is now always NULL. PyType_GetDict() provides the correct dict object instead.

Python 3.12.0 beta 3

Release date: 2023-06-19

Core and Builtins

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

• gh-105831: Fix an f-string bug, where using a debug expression (the = sign) that appears in the last line of a file results to the debug buffer that holds the expression text being one character too small.

• gh-105800: Correctly issue SyntaxWarning in f-strings if invalid sequences are used. Patch by Pablo Galindo

• gh-105587: The runtime can’t guarantee that immortal objects will not be mutated by Extensions. Thus, this modifies _PyStaticObject_CheckRefcnt to warn instead of asserting.

• gh-105564: Don’t include artificil newlines in the line attribute of tokens in the APIs of the tokenize module. Patch by Pablo Galindo

• gh-105549: Tokenize separately NUMBER and NAME tokens that are not ambiguous. Patch by Pablo Galindo.

• 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-105435: Fix spurious newline character if file ends on a comment without a newline. Patch by Pablo Galindo

• gh-105390: Correctly raise tokenize.TokenError exceptions instead of SyntaxError for tokenize errors such as incomplete input. Patch by Pablo Galindo

• gh-104812: The “pending call” machinery now works for all interpreters, not just the main interpreter, and runs in all threads, not just the main thread. Some calls are still only done in the main thread, ergo in the main interpreter. This change does not affect signal handling nor the existing public C-API (Py_AddPendingCall()), which both still only target the main thread. The new functionality is meant strictly for internal use for now, since consequences of its use are not well understood yet outside some very restricted cases. This change brings the capability in line with the intention when the state was made per-interpreter several years ago.

Library

• gh-105808: Fix a regression introduced in gh-101251 for 3.12, causing gzip.GzipFile.flush() to not flush the compressor (nor pass along the zip_mode argument).

• gh-104799: Enable ast.unparse() to unparse function and class definitions created without the new type_params field from PEP 695. Patch by Jelle Zijlstra.

• gh-105745: Fix webbrowser.Konqueror.open method.

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

• 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-104310: In the beta 1 release we added a utility function for extension module authors, to use when testing their module for support in multiple interpreters or under a per-interpreter GIL. The name of that function has changed from allowing_all_extensions to _incompatible_extension_module_restrictions. The default for the “disable_check” argument has change from True to False, to better match the new function name.

• gh-104996: Improve performance of pathlib.PurePath initialisation by deferring joining of paths when multiple arguments are given.

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

Tests

• gh-105084: When the Python build is configured --with-wheel-pkg-dir, tests requiring the setuptools and wheel wheels will search for the wheels in WHEEL_PKG_DIR.

Windows

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

C API

• gh-105375: Fix a bug in PyErr_WarnExplicit() where an exception could end up being overwritten if the API failed internally.

• gh-105603: We’ve renamed the new (in 3.12) PyInterpreterConfig.own_gil to PyInterpreterConfig.gil and changed the meaning of the value from “bool” to an integer with supported values of PyInterpreterConfig_DEFAULT_GIL, PyInterpreterConfig_SHARED_GIL, and PyInterpreterConfig_OWN_GIL. The default is “shared”.

• gh-105387: In the limited C API version 3.12, Py_INCREF() and Py_DECREF() functions are now implemented as opaque function calls to hide implementation details. Patch by Victor Stinner.

• gh-103968: PyType_FromMetaclass() now allows metaclasses with tp_new set to NULL.

Python 3.12.0 beta 2

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-99108: Refresh our new HACL* built-in hashlib code from upstream. Built-in SHA2 should be faster and an issue with SHA3 on 32-bit platforms is fixed.

Core and Builtins

• gh-105259: Don’t include newline character for trailing NEWLINE tokens emitted in the tokenize module. Patch by Pablo Galindo

• gh-105324: Fix the main function of the tokenize module when reading from sys.stdin. Patch by Pablo Galindo

• gh-98963: Restore the ability for a subclass of property to define __slots__ or otherwise be dict-less by ignoring failures to set a docstring on such a class. This behavior had regressed in 3.12beta1. An AttributeError where there had not previously been one was disruptive to existing code.

• gh-105194: Do not escape with backslashes f-string format specifiers. Patch by Pablo Galindo

• gh-105162: Fixed bug in generator.close()/throw() where an inner iterator would be ignored when the outer iterator was instrumented.

• 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-104799: Attributes of ast nodes that are lists now default to the empty list if omitted. This means that some code that previously raised TypeError when the AST node was used will now proceed with the empty list instead. Patch by Jelle Zijlstra.

• gh-105035: Fix super() calls on types with custom tp_getattro implementation (e.g. meta-types.)

• gh-105017: Show CRLF lines in the tokenize string attribute in both NL and NEWLINE tokens. Patch by Marta Gómez.

• gh-105013: Fix handling of multiline parenthesized lambdas in inspect.getsource(). Patch by Pablo Galindo

• gh-105017: Do not include an additional final NL token when parsing files having CRLF lines. Patch by Marta Gómez.

• gh-104976: Ensure that trailing DEDENT tokenize.TokenInfo objects emitted by the tokenize module are reported as in Python 3.11. Patch by Pablo Galindo

• gh-104972: Ensure that the line attribute in tokenize.TokenInfo objects in the tokenize module are always correct. Patch by Pablo Galindo

• gh-104955: Fix signature for the new __release_buffer__() slot. Patch by Jelle Zijlstra.

• gh-104690: Starting new threads and process creation through os.fork() during interpreter shutdown (such as from atexit handlers) is no longer supported. It can lead to race condition between the main Python runtime thread freeing thread states while internal threading routines are trying to allocate and use the state of just created threads. Or forked children trying to use the mid-shutdown runtime and thread state in the child process.

• gh-104879: Fix crash when accessing the __module__ attribute of type aliases defined outside a module. Patch by Jelle Zijlstra.

• gh-104825: Tokens emitted by the tokenize module do not include an implicit \n character in the line attribute anymore. Patch by Pablo Galindo

Library

• gh-105280: Fix bug where isinstance([], collections.abc.Mapping) could evaluate to True if garbage collection happened at the wrong time. The bug was caused by changes to the implementation of typing.Protocol in Python 3.12.

• gh-105239: Fix longstanding bug where issubclass(object, typing.Protocol) would evaluate to True in some edge cases. Patch by Alex Waygood.

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

• gh-105144: Fix a recent regression in the typing module. The regression meant that doing class Foo(X, typing.Protocol), where X was a class that had abc.ABCMeta as its metaclass, would then cause subsequent isinstance(1, X) calls to erroneously raise TypeError. Patch by Alex Waygood.

• gh-105113: Improve performance of pathlib.PurePath.match() by compiling an re.Pattern object for the entire pattern.

• gh-101588: Deprecate undocumented copy/deepcopy/pickle support for itertools.

• gh-103631: Fix pathlib.PurePosixPath(pathlib.PureWindowsPath(...)) not converting path separators to restore 3.11 compatible behavior.

• gh-104947: Make comparisons between pathlib.PureWindowsPath objects consistent across Windows and Posix to match 3.11 behavior.

• gh-104935: Fix bugs with the interaction between typing.runtime_checkable() and typing.Generic that were introduced by the PEP 695 implementation. Patch by Jelle Zijlstra.

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

• gh-104799: Adjust the location of the (see PEP 695) type_params field on ast.ClassDef, ast.AsyncFunctionDef, and ast.FunctionDef to better preserve backward compatibility. Patch by Jelle Zijlstra

• gh-104797: Allow typing.Protocol classes to inherit from collections.abc.Buffer. Patch by Jelle Zijlstra.

• 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-99108: We now release the GIL around built-in hashlib computations of reasonable size for the SHA families and MD5 hash functions, matching what our OpenSSL backed hash computations already does.

• 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-102024: Reduce calls of _idle_semaphore.release() in concurrent.futures.thread._worker().

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.

Build

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

• gh-89886: Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate !configure.

Windows

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

• gh-103646: When installed from the Microsoft Store, pip no longer defaults to per-user installs. However, as the install directory is unwritable, it should automatically decide to do a per-user install anyway. This should resolve issues when pip is passed an option that conflicts with --user.

• gh-88745: Improve performance of shutil.copy2() by using the operating system’s CopyFile2 function. This may result in subtle changes to metadata copied along with some files, bringing them in line with normal OS behavior.

• gh-104820: Fixes stat() and related functions on file systems that do not support file ID requests. This includes FAT32 and exFAT.

• gh-104803: Add os.path.isdevdrive() to detect whether a path is on a Windows Dev Drive. Returns False on platforms that do not support Dev Drive, and is absent on non-Windows platforms.

macOS

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

IDLE

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

C API

• gh-105115: PyTypeObject.tp_bases (and tp_mro) for builtin static types are now shared by all interpreters, whereas in 3.12-beta1 they were stored on PyInterpreterState. Also note that now the tuples are immortal objects.

• gh-105071: Add PyUnstable_Exc_PrepReraiseStar to the unstable C api to expose the implementation of except*.

• gh-104668: Don’t call PyOS_InputHook or PyOS_ReadlineFunctionPointer in subinterpreters, since it’s generally difficult to avoid using global state in their registered callbacks. This also avoids situations where extensions may find themselves running in a subinterpreter they don’t support (or haven’t yet been loaded in).

Python 3.12.0 beta 1

Release date: 2023-05-22

Security

• 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-99108: Upgrade built-in hashlib SHA3 implementation to a verified implementation from the HACL* project. Used when OpenSSL is not present or lacks SHA3.

• 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-102856: Implement PEP 701 changes in the tokenize module. Patch by Marta Gómez Macías and Pablo Galindo Salgado

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

• gh-104572: Improve syntax error message for invalid constructs in PEP 695 contexts and in annotations when from __future__ import annotations is active.

• 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-103082: Change behavior of sys.monitoring.events.LINE events in sys.monitoring: Line events now occur when a new line is reached dynamically, instead of using a static approximation, as before. This makes the behavior very similar to that of “line” events in sys.settrace. This should ease porting of tools from 3.11 to 3.12.

• gh-104263: Fix float("nan") to produce a quiet NaN on platforms (like MIPS) where the meaning of the signalling / quiet bit is inverted from its usual meaning. Also introduce a new macro Py_INFINITY matching C99’s INFINITY, and refactor internals to rely on C99’s NAN and INFINITY macros instead of hard-coding bit patterns for infinities and NaNs. Thanks Sebastian Berg.

• gh-99113: Multi-phase init extension modules may now indicate that they support running in subinterpreters that have their own GIL. This is done by using Py_MOD_PER_INTERPRETER_GIL_SUPPORTED as the value for the Py_mod_multiple_interpreters module def slot. Otherwise the module, by default, cannot be imported in such subinterpreters. (This does not affect the main interpreter or subinterpreters that do not have their own GIL.) In addition to the isolation that multi-phase init already normally requires, support for per-interpreter GIL involves one additional constraint: thread-safety. If the module has external (linked) dependencies and those libraries have any state that isn’t thread-safe then the module must do the additional work to add thread-safety. This should be an uncommon case.

• gh-99113: The GIL is now (optionally) per-interpreter. This is the fundamental change for PEP 684. This is all made possible by virtue of the isolated state of each interpreter in the process. The behavior of the main interpreter remains unchanged. Likewise, interpreters created using Py_NewInterpreter() are not affected. To get an interpreter with its own GIL, call Py_NewInterpreterFromConfig().

• gh-104108: Multi-phase init extension modules may now indicate whether or not they actually support multiple interpreters. By default such modules are expected to support use in multiple interpreters. In the uncommon case that one does not, it may use the new Py_mod_multiple_interpreters module def slot. A value of 0 means the module does not support them. 1 means it does. The default is 1.

• gh-104142: Fix an issue where list or tuple repetition could fail to respect PEP 683.

• gh-104078: Improve the performance of PyObject_HasAttrString()

• gh-104066: Improve the performance of hasattr() for module objects with a missing attribute.

• gh-104028: Reduce object creation while calling callback function from gc. Patch by Donghee Na.

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

• gh-102213: Fix performance loss when accessing an object’s attributes with __getattr__ defined.

• gh-103895: Improve handling of edge cases in showing Exception.__notes__. Ensures that the messages always end with a newline and that string/bytes are not exploded over multiple lines. Patch by Carey Metcalfe.

• gh-103907: Don’t modify the refcounts of known immortal objects (True, False, and None) in the main interpreter loop.

• gh-103899: Provide a helpful hint in the TypeError message when accidentally calling a module object that has a callable attribute of the same name (such as dis.dis() or datetime.datetime).

• gh-103845: Remove both line and instruction instrumentation before adding new ones for monitoring, to avoid newly added instrumentation being removed immediately.

• gh-103763: Implement PEP 695, adding syntactic support for generic classes, generic functions, and type aliases.

  A new type X = ... syntax is added for type aliases, which resolves at runtime to an instance of the new class typing.TypeAliasType. The value is lazily evaluated and is accessible through the .__value__ attribute. This is implemented as a new AST node ast.TypeAlias.

  New syntax (class X[T]: ..., def func[T](): ...) is added for defining generic functions and classes. This is implemented as a new type_params attribute on the AST nodes for classes and functions. This node holds instances of the new AST classes ast.TypeVar, ast.ParamSpec, and ast.TypeVarTuple.

  typing.TypeVar, typing.ParamSpec, typing.ParamSpecArgs, typing.ParamSpecKwargs, typing.TypeVarTuple, and typing.Generic are now implemented in C rather than Python.

  There are new bytecode instructions LOAD_LOCALS, LOAD_CLASSDICT_OR_GLOBAL, and LOAD_CLASSDICT_OR_DEREF to support correct resolution of names in class namespaces.

  Patch by Eric Traut, Larry Hastings, and Jelle Zijlstra.

• gh-103801: Adds three minor linting fixes to the wasm module caught that were caught by ruff.

• gh-103793: Optimized asyncio Task creation by deferring expensive string formatting (task name generation) from Task creation to the first time get_name is called. This makes asyncio benchmarks up to 5% faster.

• 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-103650: Change the perf map format to remove the ‘0x’ prefix from the addresses

• gh-102856: Implement the required C tokenizer changes for PEP 701. Patch by Pablo Galindo Salgado, Lysandros Nikolaou, Batuhan Taskaya, Marta Gómez Macías and sunmy2019.

• gh-100530: Clarify the error message raised when the called part of a class pattern isn’t actually a class.

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

• gh-103492: Clarify SyntaxWarning with literal is comparison by specifying which literal is problematic, since comparisons using is with e.g. None and bool literals are idiomatic.

• gh-87729: Add LOAD_SUPER_ATTR (and a specialization for super().method()) to speed up super().method() and super().attr. This makes super().method() roughly 2.3x faster and brings it within 20% of the performance of a simple method call. Patch by Vladimir Matveev and Carl Meyer.

• gh-103488: Change the internal offset distinguishing yield and return target addresses, so that the instruction pointer is correct for exception handling and other stack unwinding.

• gh-82012: The bitwise inversion operator (~) on bool is deprecated. It returns the bitwise inversion of the underlying int representation such that bool(~True) == True, which can be confusing. Use not for logical negation of bools. In the rare case that you really need the bitwise inversion of the underlying int, convert to int explicitly ~int(x).

• gh-77757: Exceptions raised in a typeobject’s __set_name__ method are no longer wrapped by a RuntimeError. Context information is added to the exception as a PEP 678 note.

• gh-103333: AttributeError now retains the name attribute when pickled and unpickled.

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

• gh-103323: We’ve replaced our use of _PyRuntime.tstate_current with a thread-local variable. This is a fairly low-level implementation detail, and there should be no change in behavior.

• gh-84436: The implementation of PEP-683 which adds Immortal Objects by using a fixed reference count that skips reference counting to make objects truly immutable.

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

• gh-103082: Implement PEP 669 Low Impact Monitoring for CPython.

• gh-88691: Reduce the number of inline CACHE entries for CALL.

• gh-102500: Make the buffer protocol accessible in Python code using the new __buffer__ and __release_buffer__ magic methods. See PEP 688 for details. Patch by Jelle Zijlstra.

• gh-97933: PEP 709: inline list, dict and set comprehensions to improve performance and reduce bytecode size.

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

• gh-98003: Complex function calls are now faster and consume no C stack space.

• bpo-39610: len() for 0-dimensional memoryview objects (such as memoryview(ctypes.c_uint8(42))) now raises a TypeError. Previously this returned 1, which was not consistent with mem_0d[0] raising an IndexError.

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

Library

• gh-104600: functools.update_wrapper() now sets the __type_params__ attribute (added by PEP 695).

• 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-104555: Fix issue where an issubclass() check comparing a class X against a runtime-checkable protocol Y with non-callable members would not cause TypeError to be raised if an isinstance() call had previously been made comparing an instance of X to Y. This issue was present in edge cases on Python 3.11, but became more prominent in 3.12 due to some unrelated changes that were made to runtime-checkable protocols. Patch by Alex Waygood.

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

• gh-104484: Added case_sensitive argument to pathlib.PurePath.match()

• 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-103857: Update datetime deprecations’ stracktrace to point to the calling line

• gh-101520: Move the core functionality of the tracemalloc module in the Python/ folder, leaving just the module wrapper in Modules/.

• gh-104392: Remove undocumented and unused _paramspec_tvars attribute from some classes in typing.

• gh-102613: Fix issue where pathlib.Path.glob() raised RecursionError when walking deep directory trees.

• gh-103000: Improve performance of dataclasses.asdict() for the common case where dict_factory is dict. Patch by David C Ellis.

• gh-104301: Allow leading whitespace in disambiguated statements in pdb.

• gh-104139: Teach urllib.parse.unsplit() to retain the "//" when assembling itms-services://?action=generate-bugs style Apple Platform Deployment URLs.

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

• gh-104310: Users may now use importlib.util.allowing_all_extensions() (a context manager) to temporarily disable the strict compatibility checks for importing extension modules in subinterpreters.

• 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-102613: Improve performance of pathlib.Path.glob() when expanding recursive wildcards (”**”) by merging adjacent wildcards and de-duplicating results only when necessary.

• gh-65772: Remove unneeded comments and code in turtle.py.

• gh-90208: Fixed issue where pathlib.Path.glob() returned incomplete results when it encountered a PermissionError. This method now suppresses all OSError exceptions, except those raised from calling is_dir() on the top-level path.

• gh-104144: Optimize asyncio.TaskGroup when using asyncio.eager_task_factory(). Skip scheduling a done callback if a TaskGroup task completes eagerly.

• gh-104144: Optimize asyncio.gather() when using asyncio.eager_task_factory() to complete eagerly if all fututres completed eagerly. Avoid scheduling done callbacks for futures that complete eagerly.

• gh-104114: Fix issue where pathlib.Path.glob() returns paths using the case of non-wildcard segments for corresponding path segments, rather than the real filesystem case.

• gh-104104: Improve performance of pathlib.Path.glob() by using re.IGNORECASE to implement case-insensitive matching.

• gh-104102: Improve performance of pathlib.Path.glob() when evaluating patterns that contain '../' segments.

• gh-103822: Update the return type of weekday to the newly added Day attribute

• gh-103629: Update the repr of typing.Unpack according to PEP 692.

• gh-103963: Make dis display the names of the args for CALL_INTRINSIC_*.

• 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-103977: Improve import time of platform module.

• gh-88773: Added turtle.teleport() to the turtle module to move a turtle to a new point without tracing a line, visible or invisible. Patch by Liam Gersten.

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

• gh-68968: Fixed garbled output of assertEqual() when an input lacks final newline.

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

• gh-102628: Substitute CTRL-D with CTRL-Z in sqlite3 CLI banner when running on Windows.

• gh-103636: Module-level attributes January and February are deprecated from calendar.

• gh-103583: Isolate _multibytecodec and codecs extension modules. Patches 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-99944: Make dis display the value of oparg of KW_NAMES.

• gh-74940: The C.UTF-8 locale is no longer converted to en_US.UTF-8, enabling the use of UTF-8 encoding on systems which have no locales installed.

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

• gh-103857: Deprecated datetime.datetime.utcnow() and datetime.datetime.utcfromtimestamp(). (Patch by Paul Ganssle)

• gh-103839: Avoid compilation error due to tommath.h not being found when building Tkinter against Tcl 8.7 built with bundled libtommath.

• gh-103791: contextlib.suppress now supports suppressing exceptions raised as part of an ExceptionGroup. If other exceptions exist on the group, they are re-raised in a group that does not contain the suppressed exceptions.

• gh-90750: Use datetime.datetime.fromisocalendar() in the implementation of datetime.datetime.strptime(), which should now accept only valid ISO dates. (Patch by Paul Ganssle)

• 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-103699: Add __orig_bases__ to non-generic TypedDicts, call-based TypedDicts, and call-based NamedTuples. Other TypedDicts and NamedTuples already had the attribute.

• gh-103693: Add convenience variable feature to pdb

• gh-92248: Deprecate type, choices, and metavar parameters of argparse.BooleanOptionalAction.

• gh-89415: Add socket constants for source-specific multicast. Patch by Reese Hyde.

• gh-103673: socketserver gains ForkingUnixStreamServer and ForkingUnixDatagramServer classes. Patch by Jay Berry.

• gh-103636: Added Enum for months and days in the calendar module.

• gh-84976: Create a new Lib/_pydatetime.py file that defines the Python version of the datetime module, and make datetime import the contents of the new library only if the C implementation is missing. Currently, the full Python implementation is defined and then deleted if the C implementation is not available, slowing down import datetime unnecessarily.

• gh-103596: Attributes/methods are no longer shadowed by same-named enum members, although they may be shadowed by enum.property’s.

• gh-103584: Updated importlib.metadata with changes from importlib_metadata 5.2 through 6.5.0, including: Support installed-files.txt for Distribution.files when present. PackageMetadata now stipulates an additional get method allowing for easy querying of metadata keys that may not be present. packages_distributions now honors packages and modules with Python modules that not .py sources (e.g. .pyc, .so). Expand protocol for PackageMetadata.get_all to match the upstream implementation of email.message.Message.get_all in python/typeshed#9620. Deprecated use of Distribution without defining abstract methods. Deprecated expectation that PackageMetadata.__getitem__ will return None for missing keys. In the future, it will raise a KeyError.

• 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-103548: Improve performance of pathlib.Path.absolute() and cwd() by joining paths only when necessary. Also improve performance of pathlib.PurePath.is_absolute() on Posix by skipping path parsing and normalization.

• gh-103538: Remove _tkinter module code guarded by definition of the TK_AQUA macro which was only needed for Tk 8.4.7 or earlier and was never actually defined by any build system or documented for manual use.

• gh-103533: Update cProfile to use PEP 669 API

• gh-103525: Fix misleading exception message when mixed str and bytes arguments are supplied to pathlib.PurePath and Path.

• gh-103489: Add getconfig() and setconfig() to Connection to make configuration changes to a database connection. Patch by Erlend E. Aasland.

• 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-103462: Fixed an issue with using writelines() in asyncio to send very large payloads that exceed the amount of data that can be written in one call to socket.socket.send() or socket.socket.sendmsg(), resulting in the remaining buffer being left unwritten.

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

• gh-103092: Isolate _collections (apply PEP 687). Patch by Erlend E. Aasland.

• gh-103357: Added support for logging.Formatter defaults parameter to logging.config.dictConfig() and logging.config.fileConfig(). Patch by Bar Harel.

• gh-103092: Adapt the winreg extension module to PEP 687.

• gh-74690: The performance of isinstance() checks against runtime-checkable protocols has been considerably improved for protocols that only have a few members. To achieve this improvement, several internal implementation details of the typing module have been refactored, including typing._ProtocolMeta.__instancecheck__, typing._is_callable_members_only, and typing._get_protocol_attrs. Patches by Alex Waygood.

• gh-74690: The members of a runtime-checkable protocol are now considered “frozen” at runtime as soon as the class has been created. See “What’s new in Python 3.12” for more details.

• 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-102778: Support sys.last_exc in idlelib.

• gh-103285: Improve performance of ast.get_source_segment().

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

• gh-103092: Adapt the msvcrt extension module to PEP 687.

• gh-103092: Adapt the winsound extension module to PEP 687.

• gh-93910: Remove deprecation of enum member.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-103092: Isolate _socket (apply PEP 687). Patch by Erlend E. Aasland.

• gh-100479: Add pathlib.PurePath.with_segments(), which creates a path object from arguments. This method is called whenever a derivative path is created, such as from pathlib.PurePath.parent. Subclasses may override this method to share information between path objects.

• gh-103220: Fix issue where os.path.join() added a slash when joining onto an incomplete UNC drive with a trailing slash on Windows.

• 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-75586: Fix various Windows-specific issues with shutil.which.

• gh-103193: Improve performance of inspect.getattr_static(). Patch by Alex Waygood.

• gh-103176: sys._current_exceptions() now returns a mapping from thread-id to an exception instance, rather than to a (typ, exc, tb) tuple.

• gh-103143: Polish the help messages and docstrings of pdb.

• gh-103015: Add entrypoint keyword-only parameter to sqlite3.Connection.load_extension(), for overriding the SQLite extension entry point. Patch by Erlend E. Aasland.

• gh-103000: Improve performance of dataclasses.astuple() and dataclasses.asdict() in cases where the contents are common Python types.

• 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-97696: Implemented an eager task factory in asyncio. When used as a task factory on an event loop, it performs eager execution of coroutines. Coroutines that are able to complete synchronously (e.g. return or raise without blocking) are returned immediately as a finished task, and the task is never scheduled to the event loop. If the coroutine blocks, the (pending) task is scheduled and returned.

• gh-81079: Add case_sensitive keyword-only argument to pathlib.Path.glob() and rglob().

• gh-101819: Isolate the io extension module by applying PEP 687. Patch by Kumar Aditya, Victor Stinner, and Erlend E. Aasland.

• gh-91896: Deprecate collections.abc.ByteString

• gh-101362: Speed up pathlib.Path construction by omitting the path anchor from the internal list of path parts.

• gh-102114: Functions in the dis module that accept a source code string as argument now print a more concise traceback when the string contains a syntax or indentation error.

• gh-62432: The unittest runner will now exit with status code 5 if no tests were run. It is common for test runner misconfiguration to fail to find any tests, this should be an error.

• gh-78079: Fix incorrect normalization of UNC device path roots, and partial UNC share path roots, in pathlib.PurePath. Pathlib no longer appends a trailing slash to such paths.

• gh-85984: Add tty.cfmakeraw() and tty.cfmakecbreak() to tty and modernize, the behavior of tty.setraw() and tty.setcbreak() to use POSIX.1-2017 Chapter 11 “General Terminal Interface” flag masks by default.

• gh-101688: Implement types.get_original_bases() to provide further introspection for types.

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

• gh-83861: Fix datetime.astimezone method return value when invoked on a naive datetime instance that represents local time falling in a timezone transition gap. PEP 495 requires that instances with fold=1 produce earlier times than those with fold=0 in this case.

• gh-89550: Decrease execution time of some gzip file writes by 15% by adding more appropriate buffering.

• gh-95299: Remove the bundled setuptools wheel from ensurepip, and stop installing setuptools in environments created by venv.

• gh-99353: Respect the http.client.HTTPConnection .debuglevel flag in urllib.request.AbstractHTTPHandler when its constructor parameter debuglevel is not set. And do the same for *HTTPS*.

• gh-98040: Remove the long-deprecated imp module.

• gh-97850: Deprecate pkgutil.find_loader() and pkgutil.get_loader() in favor of importlib.util.find_spec().

• gh-94473: Flatten arguments in tkinter.Canvas.coords(). It now accepts not only x1, y1, x2, y2, ... and [x1, y1, x2, y2, ...], but also (x1, y1), (x2, y2), ... and [(x1, y1), (x2, y2), ...].

• gh-98040: Remove more deprecated importlib APIs: find_loader(), find_module(), importlib.abc.Finder, pkgutil.ImpImporter, pkgutil.ImpLoader.

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

• gh-96534: Support divert(4) added in FreeBSD 14.

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

• gh-94906: Support multiple steps in math.nextafter(). Patch by Shantanu Jain and Matthias Gorgens.

• gh-51574: Make tempfile.mkdtemp() return absolute paths when its dir parameter is relative.

• gh-94518: Convert private _posixsubprocess.fork_exec() to use Argument Clinic.

• gh-92184: When creating zip files using zipfile, os.altsep, if not None, will always be treated as a path separator even when it is not /. Patch by Carey Metcalfe.

• bpo-46797: Deprecation warnings are now emitted for ast.Num, ast.Bytes, ast.Str, ast.NameConstant and ast.Ellipsis. These have been documented as deprecated since Python 3.8, and will be removed in Python 3.14.

• bpo-44844: Enables webbrowser to detect and launch Microsoft Edge browser.

• bpo-45606: Fixed the bug in pathlib.Path.glob() – previously a dangling symlink would not be found by this method when the pattern is an exact match, but would be found when the pattern contains a wildcard or the recursive wildcard (**). With this change, a dangling symlink will be found in both cases.

• bpo-23041: Add QUOTE_STRINGS and QUOTE_NOTNULL to the suite of csv module quoting styles.

• bpo-24964: Added http.client.HTTPConnection.get_proxy_response_headers() that provides access to the HTTP headers on a proxy server response to the CONNECT request.

• bpo-17258: multiprocessing now supports stronger HMAC algorithms for inter-process connection authentication rather than only HMAC-MD5.

• bpo-39744: Make asyncio.subprocess.Process.communicate() close the subprocess’s stdin even when called with input=None.

• bpo-22708: http.client CONNECT method tunnel improvements: Use HTTP 1.1 protocol; send a matching Host: header with CONNECT, if one is not provided; convert IDN domain names to Punycode. Patch by Michael Handler.

Documentation

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

• gh-103629: Mention the new way of typing **kwargs with Unpack and TypedDict introduced in PEP 692.

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

• gh-86094: Add support for Unicode Path Extra Field in ZipFile. Patch by Yeojin Kim and Andrea Giudiceandrea

• gh-99202: Fix extension type from documentation for compiling in C++20 mode

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-86275: Added property-based tests to the zoneinfo tests, along with stubs for the hypothesis interface. (Patch by Paul Ganssle)

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

• gh-102795: fix use of poll in test_epoll’s test_control_and_wait

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

Build

• gh-101282: BOLT optimization is now applied to the libpython shared library if building a shared library. BOLT instrumentation and application settings can now be influenced via the BOLT_INSTRUMENT_FLAGS and BOLT_APPLY_FLAGS configure variables.

• gh-99017: PYTHON_FOR_REGEN now require Python 3.10 or newer.

• gh-104490: Define .PHONY / virtual make targets consistently and properly.

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

• gh-103532: The TKINTER_PROTECT_LOADTK macro is no longer defined or used in the _tkinter module. It was previously only defined when building against Tk 8.4.13 and older, but Tk older than 8.5.12 has been unsupported since gh-91152.

• 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.

• gh-100220: Changed the default value of the SHELL Makefile variable from /bin/sh to /bin/sh -e to ensure that complex recipes correctly fail after an error. Previously, make install could fail to install some files and yet return a successful result.

• gh-90656: Add platform triplets for 64-bit LoongArch:

  • loongarch64-linux-gnusf

  • loongarch64-linux-gnuf32

  • loongarch64-linux-gnu

  Patch by Zhang Na.

Windows

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

• gh-82814: Fix a potential [Errno 13] Permission denied when using shutil.copystat() within Windows Subsystem for Linux (WSL) on a mounted filesystem by adding errno.EACCES to the list of ignored errors within the internal implementation.

• gh-103088: Fix virtual environment activate script having incorrect line endings for Cygwin.

• gh-103088: Fixes venvs not working in bash on Windows across different disks

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

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

• gh-103545: Add os.PRIO_DARWIN_THREAD, os.PRIO_DARWIN_PROCESS, os.PRIO_DARWIN_BG and os.PRIO_DARWIN_NONUI. These can be used with os.setpriority to run the process at a lower priority and make use of the efficiency cores on Apple Silicon systems.

• gh-104180: Support reading SOCKS proxy configuration from macOS System Configuration. Patch by Sam Schott.

• gh-60436: update curses textbox to additionally handle backspace using the curses.ascii.DEL key press.

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

IDLE

• 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.

Tools/Demos

• gh-104389: Argument Clinic C converters now accept the unused keyword, for wrapping a parameter with Py_UNUSED. Patch by Erlend E. Aasland.

C API

• gh-101291: Added unstable C API for extracting the value of “compact” integers: PyUnstable_Long_IsCompact() and PyUnstable_Long_CompactValue().

• gh-104109: We’ve added Py_NewInterpreterFromConfig() and PyInterpreterConfig to the public C-API (but not the stable ABI; not yet at least). The new function may be used to create a new interpreter with various features configured. The function was added to support PEP 684 (per-interpreter GIL).

• gh-103968: PyType_FromSpec() and its variants now allow creating classes whose metaclass overrides tp_new. The tp_new is ignored. This behavior is deprecated and will be disallowed in 3.14+. The new PyType_FromMetaclass() already disallows it.

• gh-103743: Add PyUnstable_Object_GC_NewWithExtraData() function that can be used to allocate additional memory after an object for data not managed by Python.

• gh-103295: Introduced PyUnstable_WritePerfMapEntry(), PyUnstable_PerfMapState_Init() and PyUnstable_PerfMapState_Fini(). These allow extension modules (JIT compilers in particular) to write to perf-map files in a thread safe manner. The Python support for the Linux perf profiler also uses these APIs to write entries in the perf-map file.

• gh-103509: Added C API for extending types whose instance memory layout is opaque: PyType_Spec.basicsize can now be zero or negative, PyObject_GetTypeData() can be used to get subclass-specific data, and Py_TPFLAGS_ITEMS_AT_END can be used to safely extend variable-size objects. See PEP 697 for details.

• gh-103091: Add a new C-API function to eagerly assign a version tag to a PyTypeObject: PyUnstable_Type_AssignVersionTag().

• gh-101408: PyObject_GC_Resize should calculate preheader size if needed. Patch by Donghee Na.

• gh-98836: Add support of more formatting options (left aligning, octals, uppercase hexadecimals, intmax_t, ptrdiff_t, wchar_t C strings, variable width and precision) in PyUnicode_FromFormat() and PyUnicode_FromFormatV().

• gh-96803: Add unstable C-API functions to get the code object, lasti and line number from the internal _PyInterpreterFrame in the limited API. The functions are:

  • PyCodeObject * PyUnstable_InterpreterFrame_GetCode(struct _PyInterpreterFrame *frame)

  • int PyUnstable_InterpreterFrame_GetLasti(struct _PyInterpreterFrame *frame)

  • int PyUnstable_InterpreterFrame_GetLine(struct _PyInterpreterFrame *frame)

Python 3.12.0 alpha 7

Release date: 2023-04-04

Core and Builtins

• gh-102192: Deprecated _PyErr_ChainExceptions in favour of _PyErr_ChainExceptions1.

• gh-89987: Reduce the number of inline CACHE entries for BINARY_SUBSCR.

• gh-102859: Removed JUMP_IF_FALSE_OR_POP and JUMP_IF_TRUE_OR_POP instructions.

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

• gh-102778: Add sys.last_exc and deprecate sys.last_type, sys.last_value and sys.last_traceback, which hold the same information in its legacy form.

• gh-100982: Replace all occurrences of COMPARE_AND_BRANCH with COMPARE_OP.

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

• gh-102755: Add PyErr_DisplayException() which takes just an exception instance, to replace the legacy PyErr_Display() which takes the (typ, exc, tb) triplet.

• gh-102594: Add note to exception raised in PyErr_SetObject when normalization fails.

• gh-90997: Shrink the number of inline CACHE entries used by LOAD_GLOBAL.

• gh-102491: Improve import time of platform by removing IronPython version parsing. The IronPython version parsing was not functional (see https://github.com/IronLanguages/ironpython3/issues/1667).

• gh-101291: Rearrage bits in first field (after header) of PyLongObject. * Bits 0 and 1: 1 - sign. I.e. 0 for positive numbers, 1 for zero and 2 for negative numbers. * Bit 2 reserved (probably for the immortal bit) * Bits 3+ the unsigned size.

  This makes a few operations slightly more efficient, and will enable a more compact and faster 2s-complement representation of most ints in future.

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

• gh-102406: codecs encoding/decoding errors now get the context information (which operation and which codecs) attached as PEP 678 notes instead of through chaining a new instance of the exception.

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

• gh-102300: Reuse operands with refcount of 1 in float specializations of BINARY_OP.

• gh-102213: Fix performance loss when accessing an object’s attributes with __getattr__ defined.

• gh-102255: Improve build support for the Xbox. Patch by Max Bachmann.

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

• gh-101865: Deprecate co_lnotab in code objects, schedule it for removal in Python 3.14

• bpo-1635741: Adapt _pickle to PEP 687. Patch by Mohamed Koubaa and Erlend Aasland.

Library

• gh-103085: Pure python locale.getencoding() will not warn deprecation.

• gh-103068: It’s no longer possible to register conditional breakpoints in Pdb that raise SyntaxError. Patch by Tian Gao.

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

• gh-103056: Ensure final _generate_next_value_ is a staticmethod.

• gh-103046: Display current line label correctly in dis when show_caches is False and lasti points to a CACHE entry.

• gh-102433: isinstance() checks against runtime-checkable protocols now use inspect.getattr_static() rather than hasattr() to lookup whether attributes exist. This means that descriptors and __getattr__() methods are no longer unexpectedly evaluated during isinstance() checks against runtime-checkable protocols. However, it may also mean that some objects which used to be considered instances of a runtime-checkable protocol may no longer be considered instances of that protocol on Python 3.12+, and vice versa. Most users are unlikely to be affected by this change. Patch by Alex Waygood.

• gh-103023: It’s no longer possible to register expressions to display in Pdb that raise SyntaxError. Patch by Tian Gao.

• 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-102871: Remove support for obsolete browsers from webbrowser. Removed browsers include Grail, Mosaic, Netscape, Galeon, Skipstone, Iceape, Firebird, and Firefox versions 35 and below.

• gh-102839: Improve performance of math.log() arguments handling by removing the argument clinic.

• gh-102828: Add the onexc arg to shutil.rmtree(), which is like onerror but expects an exception instance rather than an exc_info tuple. Deprecate onerror.

• 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-76846: Fix issue where __new__() and __init__() methods of pathlib.PurePath and Path subclasses were not called in some circumstances.

• gh-78530: asyncio.wait() now accepts generators yielding tasks. Patch by Kumar Aditya.

• gh-102748: asyncio.iscoroutine() now returns False for generators as asyncio does not support legacy generator-based coroutines. Patch by Kumar Aditya.

• gh-102670: Optimized fmean(), correlation(), covariance(), and linear_regression() using the new math.sumprod() function.

• gh-102615: Typing: Improve the repr of generic aliases for classes generic over a ParamSpec. (Use square brackets to represent a parameter list.)

• gh-100112: asyncio.Task.get_coro() now always returns a coroutine when wrapping an awaitable object. Patch by Kumar Aditya.

• gh-102578: Speed up setting or deleting mutable attributes on non-dataclass subclasses of frozen dataclasses. Due to the implementation of __setattr__ and __delattr__ for frozen dataclasses, this previously had a time complexity of O(n). It now has a time complexity of O(1).

• gh-102519: Add os.listdrives(), os.listvolumes() and os.listmounts() functions on Windows for enumerating drives, volumes and mount points

• gh-74468: Attribute name of the extracted tarfile file object now holds filename of itself rather than of the archive it is contained in. Patch by Oleg Iarygin.

• gh-102378: Private helper method inspect._signature_strip_non_python_syntax will no longer strip / from the input string.

• gh-79940: Add inspect.getasyncgenstate() and inspect.getasyncgenlocals(). Patch by Thomas Krennwallner.

• gh-102103: Add module argument to dataclasses.make_dataclass() and make classes produced by it pickleable.

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

• gh-102038: Skip a stat in site if we have already found a pyvenv.cfg

• gh-98886: Fix issues when defining dataclasses that have fields with specific underscore names that aren’t clearly reserved by dataclasses.

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

• gh-101313: Added -h and –help arguments to the webbrowser CLI

• gh-100372: ssl.SSLContext.load_verify_locations() no longer incorrectly accepts some cases of trailing data when parsing DER.

• gh-89727: Fix pathlib.Path.walk RecursionError on deep directory trees by rewriting it using iteration instead of recursion.

• gh-100131: Added an optional delete keyword argument to tempfile.TemporaryDirectory.

• gh-48330: Added --durations command line option, showing the N slowest test cases. unittest.TextTestRunner and unittest.TextTestResult constructors accept a new durations keyword argument. Subclasses should take this into account or accept **kwargs. Added unittest.TestResult.addDuration() method and unittest.TestResult.collectedDurations attribute.

  (Contributed by Giampaolo Rodola)

• gh-98169: Fix dataclasses.astuple() crash when collections.defaultdict is present in the attributes.

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

• 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-94684: Now uuid.uuid3() and uuid.uuid5() functions support bytes objects as their name argument.

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

• gh-72346: Added deprecation warning to isdst parameter of email.utils.localtime().

• bpo-36305: Fix handling of Windows filenames that resemble drives, such as ./a:b, in pathlib.

Documentation

• gh-103112: Add docstring to http.client.HTTPResponse.read() to fix pydoc output.

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-101377: Improved test_locale_calendar_formatweekday of calendar.

Build

• gh-102973: Add a dev container (along with accompanying Dockerfile) for development purposes.

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

Windows

• gh-102690: Update webbrowser to fall back to Microsoft Edge instead of Internet Explorer.

• gh-99726: Improves correctness of stat results for Windows, and uses faster API when available

Tools/Demos

• gh-102809: Misc/gdbinit was removed.

C API

• gh-102013: Add a new (unstable) C-API function for iterating over GC’able objects using a callback: PyUnstable_VisitObjects.

Python 3.12.0 alpha 6

Release date: 2023-03-07

Security

• gh-99108: Replace builtin hashlib implementations of MD5 and SHA1 with verified ones from the HACL* project.

• gh-101727: Updated the OpenSSL version used in Windows and macOS binary release builds to 1.1.1t to address CVE 2023-0286, CVE 2022-4303, and CVE 2022-4303 per the OpenSSL 2023-02-07 security advisory.

• gh-99108: Replace the builtin hashlib implementations of SHA2-384 and SHA2-512 originally from LibTomCrypt with formally verified, side-channel resistant code from the HACL* project. The builtins remain a fallback only used when OpenSSL does not provide them.

• gh-101283: subprocess.Popen now uses a safer approach to find cmd.exe when launching with shell=True. Patch by Eryk Sun, based on a patch by Oleg Iarygin.

Core and Builtins

• gh-102493: Fix regression in semantics of normalisation in PyErr_SetObject.

• 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-102336: Cleanup Windows 7 specific special handling. Patch by Max Bachmann.

• gh-102250: Fixed a segfault occurring when the interpreter calls a __bool__ method that raises.

• 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: Use GetCurrentProcessId on Windows when getpid is unavailable. Patch by Max Bachmann.

• gh-102056: Fix error handling bugs in interpreter’s exception printing code, which could cause a crash on infinite recursion.

• gh-100982: Restrict the scope of the FOR_ITER_RANGE instruction to the scope of the original FOR_ITER instruction, to allow instrumentation.

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

• gh-101952: Fix possible segfault in BUILD_SET opcode, when new set created.

• gh-74895: socket.getaddrinfo no longer raises OverflowError for int port values outside of the C long range. Out of range values are left up to the underlying string based C library API to report. A socket.gaierror SAI_SERVICE may occur instead, or no error at all as not all platform C libraries generate an error.

• gh-101799: Add CALL_INTRINSIC_2 and use it instead of PREP_RERAISE_STAR.

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

• gh-84783: Make the slice object hashable. Patch by Will Bradshaw and Furkan Onder.

• gh-87849: Change the SEND instruction to leave the receiver on the stack. This allows the specialized form of SEND to skip the chain of C calls and jump directly to the RESUME in the generator or coroutine.

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

• gh-101430: Update tracemalloc to handle presize of object properly. Patch by Donghee Na.

• 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.

• gh-101632: Adds a new RETURN_CONST instruction.

• gh-100719: Remove gi_code field from generator (and coroutine and async generator) objects as it is redundant. The frame already includes a reference to the code object.

• gh-98627: When an interpreter is configured to check (and only then), importing an extension module will now fail when the extension does not support multiple interpreters (i.e. doesn’t implement PEP 489 multi-phase init). This does not apply to the main interpreter, nor to subinterpreters created with Py_NewInterpreter().

Library

• gh-102302: Micro-optimise hashing of inspect.Parameter, reducing the time it takes to hash an instance by around 40%.

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

• gh-91038: platform.platform() now has boolean default arguments.

• gh-81652: Add mmap.MAP_ALIGNED_SUPER FreeBSD and mmap.MAP_CONCEAL OpenBSD constants to mmap. 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-101566: In zipfile, sync Path with zipp 3.14, including fix for extractall on the underlying zipfile after being wrapped in Path.

• gh-97930: Apply changes from importlib_resources 5.12, including fix for MultiplexedPath to support directories in multiple namespaces (python/importlib_resources#265).

• gh-101997: Upgrade pip wheel bundled with ensurepip (pip 23.0.1)

• gh-99108: The built-in extension modules for hashlib SHA2 algorithms, used when OpenSSL does not provide them, now live in a single internal _sha2 module instead of separate _sha256 and _sha512 modules.

• 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-87634: Remove locking behavior from functools.cached_property().

• 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-101773: Optimize fractions.Fraction for small components. The private argument _normalize of the fractions.Fraction constructor has been removed.

• gh-101693: In sqlite3.Cursor.execute(), DeprecationWarning is now emitted when named placeholders are used together with parameters supplied as a sequence instead of as a dict. Starting from Python 3.14, using named placeholders with parameters supplied as a sequence will raise a ProgrammingError. Patch by Erlend E. Aasland.

• gh-101446: Change repr of collections.OrderedDict to use regular dictionary formatting instead of pairs of keys and values.

• gh-101362: Speed up pathlib.PurePath construction by handling arguments more uniformly. When a pathlib.Path argument is supplied, we use its string representation rather than joining its parts with os.path.join().

• gh-101362: Speed up pathlib.PurePath construction by calling os.path.join() only when two or more arguments are given.

• gh-101362: Speed up pathlib.Path construction by running the path flavour compatibility check only when pathlib is imported.

• gh-85984: Refactored the implementation of pty.fork() to use os.login_tty().

  A DeprecationWarning is now raised by pty.master_open() and pty.slave_open(). They were undocumented and deprecated long long ago in the docstring in favor of pty.openpty().

• gh-101561: Add a new decorator typing.override(). See PEP 698 for details. Patch by Steven Troxler.

• gh-63301: Set exit code when tabnanny CLI exits on error.

• gh-101360: Fix anchor matching in pathlib.PureWindowsPath.match(). Path and pattern anchors are now matched with fnmatch, just like other path parts. This allows patterns such as "*:/Users/*" to be matched.

• gh-101277: Remove global state from itertools module (PEP 687). Patches by Erlend E. Aasland.

• gh-100809: Fix handling of drive-relative paths (like ‘C:’ and ‘C:foo’) in pathlib.Path.absolute(). This method now uses the OS API to retrieve the correct current working directory for the drive.

• gh-99138: Apply PEP 687 to zoneinfo. Patch by Erlend E. Aasland.

• gh-96764: asyncio.wait_for() now uses asyncio.timeout() as its underlying implementation. Patch by Kumar Aditya.

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

• bpo-23224: Fix segfaults when creating lzma.LZMADecompressor and bz2.BZ2Decompressor objects without calling __init__(), and fix leakage of locks and internal buffers when calling the __init__() methods of lzma.LZMADecompressor, lzma.LZMACompressor, bz2.BZ2Compressor, and bz2.BZ2Decompressor objects multiple times.

Documentation

• gh-85417: Update cmath documentation to clarify behaviour on branch cuts.

• gh-97725: Fix asyncio.Task.print_stack() description for file=None. Patch by Oleg Iarygin.

Tests

• gh-102019: Fix deadlock on shutdown if test_current_{exception,frames} fails. Patch by Jacob Bower.

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

• 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.

Build

• gh-99942: On Android, in a static build, python-config in embed mode no longer incorrectly reports a library to link to.

• gh-99942: On Android, python.pc now correctly reports the library to link to, the same as python-config.sh.

• gh-100221: Fix creating install directories in make sharedinstall if they exist outside DESTDIR already.

• gh-96821: Explicitly mark C extension modules that need defined signed integer overflow, and add a configure option --with-strict-overflow. Patch by Matthias Görgens and Shantanu Jain.

Windows

• gh-102344: Implement winreg.QueryValue using QueryValueEx and winreg.SetValue using SetValueEx. Patch by Max Bachmann.

• gh-101881: Handle read and write operations on non-blocking pipes properly on Windows.

• gh-101881: Add support for the os.get_blocking() and os.set_blocking() functions on 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.

• gh-101196: The functions os.path.isdir, os.path.isfile, os.path.islink and os.path.exists are now 13% to 28% faster on Windows, by making fewer Win32 API calls.

macOS

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

C API

• gh-101907: Removes use of non-standard C++ extension in public header files.

• gh-99293: Document that the Py_TPFLAGS_VALID_VERSION_TAG is an internal feature, should not be used, and will be removed.

• gh-101578: Add PyErr_GetRaisedException() and PyErr_SetRaisedException() for saving and restoring the current exception. These functions return and accept a single exception object, rather than the triple arguments of the now-deprecated PyErr_Fetch() and PyErr_Restore(). This is less error prone and a bit more efficient.

  Add PyException_GetArgs() and PyException_SetArgs() as convenience functions for retrieving and modifying the args passed to the exception’s constructor.

• gh-91744: Introduced the Unstable C API tier, marking APi that is allowed to change in minor releases without a deprecation period. See PEP 689 for details.

Python 3.12.0 alpha 5

Release date: 2023-02-07

Security

• gh-99108: Replace the builtin hashlib implementations of SHA2-224 and SHA2-256 originally from LibTomCrypt with formally verified, side-channel resistant code from the HACL* project. The builtins remain a fallback only used when OpenSSL does not provide them.

Core and Builtins

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

• gh-59956: The GILState API is now partially compatible with subinterpreters. Previously, PyThreadState_GET() and PyGILState_GetThisThreadState() would get out of sync, causing inconsistent behavior and crashes.

• 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-101266: Fix sys.getsizeof() reporting for int subclasses.

• gh-101291: Refactor the PyLongObject struct into a normal Python object header and a PyLongValue struct.

• 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-100762: Record the (virtual) exception block depth in the oparg of YIELD_VALUE. Use this to avoid the expensive throw() when closing generators (and coroutines) that can be closed trivially.

• gh-100982: Adds a new COMPARE_AND_BRANCH instruction. This is a bit more efficient when performing a comparison immediately followed by a branch, and restores the design intent of PEP 659 that specializations are local to a single instruction.

• 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-100923: Remove the mask cache entry for the COMPARE_OP instruction and embed the mask into the oparg.

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

• gh-91351: Fix a case where re-entrant imports could corrupt the import deadlock detection code and cause a KeyError to be raised out of importlib/_bootstrap. In addition to the straightforward cases, this could also happen when garbage collection leads to a warning being emitted – as happens when it collects an open socket or file)

• gh-100726: Optimize construction of range object for medium size integers.

• gh-100712: Added option to build cpython with specialization disabled, by setting ENABLE_SPECIALIZATION=False in opcode, followed by make regen-all.

• bpo-32780: Inter-field padding is now inserted into the PEP3118 format strings obtained from ctypes.Structure objects, reflecting their true representation in memory.

Library

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

• gh-101570: Upgrade pip wheel bundled with ensurepip (pip 23.0)

• gh-101323: Fix a bug where errors where not thrown by zlib._ZlibDecompressor if encountered during decompressing.

• gh-101317: Add ssl_shutdown_timeout parameter for asyncio.StreamWriter.start_tls().

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

• gh-92123: Adapt the _elementtree extension module to multi-phase init (PEP 489). Patches by Erlend E. Aasland.

• 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-94518: Group-related variables of _posixsubprocess module are renamed to stress that supplimentary group affinity is added to a fork, not replace the inherited ones. Patch by Oleg Iarygin.

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

• gh-101000: Add os.path.splitroot(), which splits a path into a 3-item tuple (drive, root, tail). This new function is used by pathlib to improve the performance of path construction by up to a third.

• 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-39615: warnings.warn() now has the ability to skip stack frames based on code filename prefix rather than only a numeric stacklevel via the new skip_file_prefixes keyword argument.

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

• gh-100160: Emit a deprecation warning in asyncio.DefaultEventLoopPolicy.get_event_loop() if there is no current event loop set and it decides to create one.

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

• gh-67790: Add float-style formatting support for fractions.Fraction instances.

• gh-99266: Preserve more detailed error messages in ctypes.

• gh-86682: Ensure runtime-created collections have the correct module name using the newly added (internal) sys._getframemodulename().

• gh-88597: uuid now has a command line interface. Try python -m uuid -h.

• gh-60580: ctypes.wintypes.BYTE definition changed from c_byte to c_ubyte to match Windows SDK. Patch by Anatoly Techtonik and Oleg Iarygin.

• gh-94518: _posixsubprocess now initializes all UID and GID variables using a reserved -1 value instead of a separate flag. Patch by Oleg Iarygin.

• bpo-38941: The xml.etree.ElementTree module now emits DeprecationWarning when testing the truth value of an xml.etree.ElementTree.Element. Before, the Python implementation emitted FutureWarning, and the C implementation emitted nothing.

• bpo-40077: Convert elementtree types to heap types. Patch by Erlend E. Aasland.

• bpo-29847: Fix a bug where pathlib.Path accepted and ignored keyword arguments. Patch provided by Yurii Karabas.

• gh-77772: ctypes.CDLL, ctypes.OleDLL, ctypes.WinDLL, and ctypes.PyDLL now accept path-like objects as their name argument. Patch by Robert Hoelzl.

Documentation

• gh-88324: Reword subprocess to emphasize default behavior of stdin, stdout, and stderr arguments. Remove inaccurate statement about child file handle inheritance.

Tests

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

Build

• gh-101282: Update BOLT configuration not to use deprecated usage of --split functions. Patch by Donghee Na.

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

• gh-77532: Minor fixes to allow building with PlatformToolset=ClangCL on Windows.

• gh-101152: In accordance with PEP 699, the ma_version_tag field in PyDictObject is deprecated for extension modules. Accessing this field will generate a compiler warning at compile time. This field will be removed in Python 3.14.

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

• gh-101060: Conditionally add -fno-reorder-blocks-and-partition in configure. Effectively fixes --enable-bolt when using Clang, as this appears to be a GCC-only flag.

• gh-98705: __bool__ is defined in AIX system header files which breaks the build in AIX, so undefine it.

• gh-98636: Fix a regression in detecting gdbm_compat library for the _gdbm module build.

• gh-96305: _aix_support now uses a simple code to get platform details rather than the now non-existent _bootsubprocess during bootstrap.

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-99834: Updates bundled copy of Tcl/Tk to 8.6.13.0

• 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.

Python 3.12.0 alpha 4

Release date: 2023-01-10

Core and Builtins

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

• gh-99005: Remove UNARY_POSITIVE, ASYNC_GEN_WRAP and LIST_TO_TUPLE, replacing them with intrinsics.

• gh-99005: Add new CALL_INTRINSIC_1 instruction. Remove IMPORT_STAR, PRINT_EXPR and STOPITERATION_ERROR, replacing them with the CALL_INTRINSIC_1 instruction.

• gh-100288: Remove the LOAD_ATTR_METHOD_WITH_DICT specialized instruction. Stats show it is not useful.

• gh-100720: Added _PyFrame_NumSlotsForCodeObject, which returns the number of slots needed in a frame for a given code object.

• gh-100719: Removed the co_nplaincellvars field from the code object, as it is redundant.

• 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-100126: Fix an issue where “incomplete” frames could be briefly visible to C code while other frames are being torn down, possibly resulting in corruption or hard crashes of the interpreter while running finalizers.

• gh-87447: Fix SyntaxError on comprehension rebind checking with names that are not actually redefined.

  Now reassigning b in [(b := 1) for a, b.prop in some_iter] is allowed. Reassigning a is still disallowed as per PEP 572.

• gh-100268: Add int.is_integer() to improve duck type compatibility between int and float.

• gh-100425: Improve the accuracy of sum() with compensated summation.

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

• gh-100357: Convert vars, dir, next, getattr, and iter to argument clinic.

• gh-100117: Improve the output of codeobject.co_lines() by emitting only one entry for each line range.

• gh-90043: Handle NaNs when specializing COMPARE_OP for float values.

• gh-100222: Redefine the _Py_CODEUNIT typedef as a union to describe its layout to the C compiler, avoiding type punning and improving clarity.

• gh-99955: Internal compiler functions (in compile.c) now consistently return -1 on error and 0 on success.

• gh-100188: The BINARY_SUBSCR_LIST_INT and BINARY_SUBSCR_TUPLE_INT instructions are no longer used for negative integers because those instructions always miss when encountering negative integers.

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

• gh-94155: Improved the hashing algorithm for code objects, mitigating some hash collisions.

• gh-99540: None now hashes to a constant value. This is not a requirements change.

• gh-100143: When built with --enable-pystats, stats collection is now off by default. To enable it early at startup, pass the -Xpystats flag. Stats are now always dumped, even if switched off.

• gh-100146: Improve BUILD_LIST opcode so that it works similarly to the BUILD_TUPLE opcode, by stealing references from the stack rather than repeatedly using stack operations to set list elements. Implementation details are in a new private API _PyList_FromArraySteal().

• gh-100110: Specialize FOR_ITER for tuples.

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

• gh-92216: Improve the performance of hasattr() for type objects with a missing attribute.

• gh-99582: Freeze zipimport module into _bootstrap_python.

• gh-99554: Pack debugging location tables more efficiently during bytecode compilation.

• gh-98522: Add an internal version number to code objects, to give better versioning of inner functions and comprehensions, and thus better specialization of those functions. This change is invisible to both Python and C extensions.

• gh-94603: Improve performance of list.pop for small lists.

• gh-89051: Add ssl.OP_LEGACY_SERVER_CONNECT

• 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-100833: Speed up math.fsum() by removing defensive volatile qualifiers.

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

• gh-100813: Add socket.IP_PKTINFO constant.

• gh-100792: Make email.message.Message.__contains__() twice as fast.

• gh-91851: Microoptimizations for fractions.Fraction.__round__(), fractions.Fraction.__ceil__() and fractions.Fraction.__floor__().

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

• 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-91219: Change SimpleHTTPRequestHandler to support subclassing to provide a different set of index file names instead of using __init__ parameters.

• gh-100690: Mock objects which are not unsafe will now raise an AttributeError when accessing an attribute that matches the name of an assertion but without the prefix assert_, e.g. accessing called_once instead of assert_called_once. This is in addition to this already happening for accessing attributes with prefixes assert, assret, asert, aseert, and assrt.

• gh-89727: Simplify and optimize os.walk() by using isinstance() checks to check the top of the stack.

• gh-100485: Add math.sumprod() to compute the sum of products.

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

• gh-97930: importlib.resources.files now accepts a module as an anchor instead of only accepting packages. If a module is passed, resources are resolved adjacent to that module (in the same package or at the package root). The parameter was renamed from package to anchor with a compatibility shim for those passing by keyword. Additionally, the new anchor parameter is now optional and will default to the caller’s module.

• gh-100585: Fixed a bug where importlib.resources.as_file was leaving file pointers open

• gh-100562: Improve performance of pathlib.Path.absolute() by nearly 2x. This comes at the cost of a performance regression in pathlib.Path.cwd(), which is generally used less frequently in user code.

• gh-100519: Small simplification of http.cookiejar.eff_request_host() that improves readability and better matches the RFC wording.

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

• gh-100488: Add Fraction.is_integer() to check whether a fractions.Fraction is an integer. This improves duck type compatibility with float and int.

• 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-100363: Speed up asyncio.get_running_loop() by removing redundant getpid checks. Patch by Kumar Aditya.

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

• gh-100348: Fix ref cycle in asyncio._SelectorSocketTransport by removing _read_ready_cb in close.

• gh-100344: Provide C implementation for asyncio.current_task() for a 4x-6x speedup.

• gh-100272: Fix JSON serialization of OrderedDict. It now preserves the order of keys.

• gh-83076: Instantiation of Mock() and AsyncMock() is now 3.8x faster.

• gh-100234: Set a default value of 1.0 for the lambd parameter in random.expovariate().

• gh-100228: A DeprecationWarning may be raised when os.fork() or os.forkpty() is called from multi-threaded processes. Forking with threads is unsafe and can cause deadlocks, crashes and subtle problems. Lack of a warning does not indicate that the fork call was actually safe, as Python may not be aware of all threads.

• gh-100039: Improve signatures for enums and flags.

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

• bpo-44592: Fixes inconsistent handling of case sensitivity of extrasaction arg in csv.DictWriter.

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

• gh-85432: Rename the fmt parameter of the pure-Python implementation of datetime.time.strftime() to format. Rename the t parameter of datetime.datetime.fromtimestamp() to timestamp. These changes mean the parameter names in the pure-Python implementation now match the parameter names in the C implementation. Patch by Alex Waygood.

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

• gh-99925: Unify error messages in JSON serialization between json.dumps(float('nan'), allow_nan=False) and json.dumps(float('nan'), allow_nan=False, indent=<SOMETHING>). Now both include the representation of the value that could not be serialized.

• gh-89727: Fix issue with os.walk() where a RecursionError would occur on deep directory structures by adjusting the implementation of os.walk() to be iterative instead of recursive.

• gh-94943: Add Dataclass support to the Enum __repr__(). When inheriting from a dataclass, only show the field names in the value section of the member repr(), and not the dataclass’ class name.

• 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-94912: Add inspect.markcoroutinefunction() decorator which manually marks a function as a coroutine for the benefit of iscoroutinefunction().

• gh-99509: Add PEP 585 support for multiprocessing.queues.Queue.

• gh-99482: Remove Jython partial compatibility code from several stdlib modules.

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

• 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-91166: asyncio is optimized to avoid excessive copying when writing to socket and use sendmsg() if the platform supports it. Patch by Kumar Aditya.

• gh-98030: Add missing TCP socket options from Linux: TCP_MD5SIG, TCP_THIN_LINEAR_TIMEOUTS, TCP_THIN_DUPACK, TCP_REPAIR, TCP_REPAIR_QUEUE, TCP_QUEUE_SEQ, TCP_REPAIR_OPTIONS, TCP_TIMESTAMP, TCP_CC_INFO, TCP_SAVE_SYN, TCP_SAVED_SYN, TCP_REPAIR_WINDOW, TCP_FASTOPEN_CONNECT, TCP_ULP, TCP_MD5SIG_EXT, TCP_FASTOPEN_KEY, TCP_FASTOPEN_NO_COOKIE, TCP_ZEROCOPY_RECEIVE, TCP_INQ, TCP_TX_DELAY.

• gh-88500: Reduced the memory usage of urllib.parse.unquote() and urllib.parse.unquote_to_bytes() on large values.

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

• 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.

• gh-78707: Deprecate passing more than one positional argument to pathlib.PurePath.relative_to() and is_relative_to().

• gh-92122: Fix reStructuredText syntax errors in docstrings in the enum module.

• gh-91851: Optimize the Fraction arithmetics for small components.

• bpo-24132: Make pathlib.PurePath and Path subclassable (private to start). Previously, attempting to instantiate a subclass resulted in an AttributeError being raised. Patch by Barney Gale.

• 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

• gh-100616: Document existing attr parameter to curses.window.vline() function in curses.

• gh-100472: Remove claim in documentation that the stripdir, prependdir and limit_sl_dest parameters of compileall.compile_dir() and compileall.compile_file() could be bytes.

• bpo-25377: Clarify use of octal format of mode argument in help(os.chmod) as well as help(os.fchmod)

Tests

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

• 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-93018: Make two tests forgiving towards host system libexpat with backported security fixes applied.

Build

• gh-100540: Removed the --with-system-ffi configure option; libffi must now always be supplied by the system on all non-Windows platforms. The option has had no effect on non-Darwin platforms for several releases, and in 3.11 only had the non-obvious effect of invoking pkg-config to find libffi and never setting -DUSING_APPLE_OS_LIBFFI. Now on Darwin platforms configure will first check for the OS libffi and then fall back to the same processing as other platforms if it is not found.

• gh-88267: Avoid exporting Python symbols in linked Windows applications when the core is built as static.

• bpo-41916: Allow override of ac_cv_cxx_thread so that cross compiled python can set -pthread for CXX.

Windows

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

• gh-99191: Use _MSVC_LANG >= 202002L instead of less-precise _MSC_VER >=1929 to more accurately test for C++20 support in PC/_wmimodule.cpp.

• gh-79218: Define MS_WIN64 for Mingw-w64 64bit, fix cython compilation failure.

• gh-99941: Ensure that asyncio.Protocol.data_received() receives an immutable bytes object (as documented), instead of bytearray.

• 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.

• bpo-34816: hasattr(ctypes.windll, 'nonexistant') now returns False instead of raising OSError.

macOS

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

• gh-100540: Removed obsolete dlfcn.h shim from the _ctypes extension module, which has not been necessary since Mac OS X 10.2.

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.

C API

• gh-99947: Raising SystemError on import will now have its cause be set to the original unexpected exception.

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

• gh-98724: The Py_CLEAR, Py_SETREF and Py_XSETREF macros now only evaluate their arguments once. If an argument has side effects, these side effects are no longer duplicated. Patch by Victor Stinner.

Python 3.12.0 alpha 3

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

Core and Builtins

• 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-91054: Add PyCode_AddWatcher() and PyCode_ClearWatcher() APIs to register callbacks to receive notification on creation and destruction of code objects.

• 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-99708: Fix bug where compiler crashes on an if expression with an empty body block.

• 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 character 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-99547: Add a function to os.path to check if a path is a junction: isjunction. Add similar functionality to pathlib.Path as is_junction.

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

• gh-99377: Add audit events for thread creation and clear operations.

• gh-98686: Remove the BINARY_OP_GENERIC and COMPARE_OP_GENERIC “specializations”.

• gh-99298: Remove the remaining error paths for attribute specializations, and refuse to specialize attribute accesses on types that haven’t had PyType_Ready() called on them yet.

• gh-99127: Allow some features of syslog to the main interpreter only. Patch by Donghee Na.

• gh-91053: Optimizing interpreters and JIT compilers may need to invalidate internal metadata when functions are modified. This change adds the ability to provide a callback that will be invoked each time a function is created, modified, or destroyed.

• gh-90994: Improve error messages when there’s a syntax error with call arguments. The following three cases are covered: - No value is assigned to a named argument, eg foo(a=). - A value is assigned to a star argument, eg foo(*args=[0]). - A value is assigned to a double-star keyword argument, eg foo(**kwarg={'a': 0}).

• bpo-45026: Optimize the range object iterator. It is now smaller, faster iteration of ranges containing large numbers. Smaller pickles, faster unpickling.

• 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-99957: Add frozen_default parameter to typing.dataclass_transform().

• gh-79033: Fix asyncio.Server.wait_closed() to actually do what the docs promise – wait for all existing connections to complete, after closing the server.

• 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-99508: Fix TypeError in Lib/importlib/_bootstrap_external.py while calling _imp.source_hash().

• gh-66285: Fix asyncio to not share event loop and signal wakeupfd in forked processes. Patch by Kumar Aditya.

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

• gh-92647: Use final status of an enum to determine lookup or creation branch of functional API.

• gh-99388: Add loop_factory parameter to asyncio.run() to allow specifying a custom event loop factory. Patch by Kumar Aditya.

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

• 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-99284: Remove _use_broken_old_ctypes_structure_semantics_ old untested and undocumented hack from ctypes.

• gh-99201: Fix IndexError when initializing the config variables on Windows if HAVE_DYNAMIC_LOADING is not set.

• 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-99029: pathlib.PurePath.relative_to() now treats naked Windows drive paths as relative. This brings its behaviour in line with other parts of pathlib.

• gh-98253: The implementation of the typing module is now more resilient to reference leaks in binary extension modules.

  Previously, a reference leak in a typed C API-based extension module could leak internals of the typing module, which could in turn introduce leaks in essentially any other package with typed function signatures. Although the typing package is not the original source of the problem, such non-local dependences exacerbate debugging of large-scale projects, and the implementation was therefore changed to reduce harm by providing better isolation.

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

• gh-93453: asyncio.get_event_loop() and many other asyncio functions like asyncio.ensure_future(), asyncio.shield() or asyncio.gather(), and also the get_event_loop() method of asyncio.BaseDefaultEventLoopPolicy now raise a RuntimeError if called when there is no running event loop and the current event loop was not set. Previously they implicitly created and set a new current event loop. DeprecationWarning is no longer emitted if there is no running event loop but the current event loop was set.

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

• gh-98248: Provide informative error messages in struct.pack() when its integral arguments are not in range.

• gh-98108: zipfile.Path is now pickleable if its initialization parameters were pickleable (e.g. for file system paths).

• gh-98098: Created packages from zipfile and test_zipfile modules, separating zipfile.Path functionality.

• 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-96828: Add an OP_ENABLE_KTLS option for enabling the use of the kernel TLS (kTLS). Patch by Illia Volochii.

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

• bpo-41260: Rename the fmt parameter of the pure Python implementation of datetime.date.strftime() to format.

• bpo-15999: All built-in functions now accept arguments of any type instead of just bool and int for boolean parameters.

Documentation

• gh-99931: Use sphinxext-opengraph to generate OpenGraph metadata.

• gh-89682: Reworded docstring of the default __contains__ to clarify that it returns a bool.

• gh-88330: Improved the description of what a resource is in importlib.resources docs.

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

• 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-99741: We’ve implemented multi-phase init (PEP 489/630/687) for the internal (for testing) _xxsubinterpreters module.

• 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-99593: Cover the Unicode C API with tests.

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

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-99289: Add a COMPILEALL_OPTS variable in Makefile to override compileall options (default: -j0) in make install. Also merged the compileall commands into a single command building .pyc files for the all optimization levels (0, 1, 2) at once. Patch by Victor Stinner.

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

• gh-88226: Always define TARGET_* labels in Python/ceval.c, even if USE_COMPUTED_GOTOS is disabled. This allows breakpoints to be set at those labels in (for instance) gdb.

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.

• 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.

Tools/Demos

• 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-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-99612: Fix PyUnicode_DecodeUTF8Stateful() for ASCII-only data: *consumed was not set.

• gh-47146: The structmember.h header is deprecated. Its non-deprecated contents are now available just by including Python.h, with a Py_ prefix added if it was missing. (Deprecated contents are T_OBJECT, T_NONE, and no-op flags.) Patch by Petr Viktorin, based on earlier work by Alexander Belopolsky and Matthias Braun.

Python 3.12.0 alpha 2

Release date: 2022-11-14

Security

• 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.

  Individual labels within an IDNA encoded DNS name will now raise an error early during IDNA decoding if they are longer than 1024 unicode characters given that each decoded DNS label must be 63 or fewer characters and the entire decoded DNS name is limited to 255. Only an application presenting a hostname or label consisting primarily of RFC 3454 section 3.1 “Nothing” characters to be removed would run into of this new limit. See also RFC 5894 section 6 and RFC 3491.

• gh-98739: Update bundled libexpat to 2.5.0

Core and Builtins

• gh-81057: The docs clearly say that PyImport_Inittab, PyImport_AppendInittab(), and PyImport_ExtendInittab() should not be used after Py_Initialize() has been called. We now enforce this for the two functions. Additionally, the runtime now uses an internal copy of PyImport_Inittab, to guard against modification.

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

• gh-99254: The compiler now removes all unused constants from code objects (except the first one, which may be a docstring).

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

• gh-81057: The 18 global C variables holding the state of the allocators have been moved to _PyRuntimeState. This is a strictly internal change with no change in behavior.

• 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-98686: Merge the adaptive opcode logic into each instruction’s unquickened variant, and merge the logic in EXTENDED_ARG_QUICK into EXTENDED_ARG. With these changes, the quickening that happens at code object creation is now only responsible for initializing warmup counters and inserting superinstructions.

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

• gh-99139: Improve the error suggestion for NameError exceptions for instances. Now if a NameError is raised in a method and the instance has an attribute that’s exactly equal to the name in the exception, the suggestion will include self.<NAME> instead of the closest match in the method scope. Patch by Pablo Galindo

• gh-98401: Octal escapes with value larger than 0o377 (ex: "\477"), deprecated in Python 3.11, now produce a SyntaxWarning, instead of DeprecationWarning. In a future Python version they will be eventually a SyntaxError. Patch by Victor Stinner.

• gh-98401: A backslash-character pair that is not a valid escape sequence now generates a SyntaxWarning, instead of DeprecationWarning. For example, re.compile("\d+\.\d+") now emits a SyntaxWarning ("\d" is an invalid escape sequence), use raw strings for regular expression: re.compile(r"\d+\.\d+"). In a future Python version, SyntaxError will eventually be raised, instead of SyntaxWarning. Patch by Victor Stinner.

• gh-96793: Handle StopIteration and StopAsyncIteration raised in generator or coroutines in the bytecode, rather than in wrapping C code.

• gh-98931: Improve the SyntaxError error message when the user types import x from y instead of from y import x. Patch by Pablo Galindo

• 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 (in-development) wasmtime 2.0.

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

• gh-98811: Use complete source locations to simplify detection of __future__ imports which are not at the beginning of the file. Also corrects the offset in the exception raised in one case, which was off by one and impeded highlighting.

• gh-96793: Add specialization of FOR_ITER for generators. Saves multiple layers of dispatch and checking to get from the FOR_ITER instruction in the caller to the RESUME in the generator.

• gh-98762: Fix source locations of match sub-patterns.

• gh-98586: Added the methods PyObject_Vectorcall() and PyObject_VectorcallMethod() to the Limited API along with the auxiliary macro constant PY_VECTORCALL_ARGUMENTS_OFFSET.

  The availability of these functions enables more efficient PEP 590 vector calls from binary extension modules that avoid argument boxing/unboxing overheads.

• 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-93143: Rather than changing co_code, the interpreter will now display a RuntimeWarning and assign None to any fast locals that are left unbound after jumps or del statements executed while tracing.

• gh-96421: When calling into Python code from C code, through PyEval_EvalFrameEx() or a related C-API function, a shim frame in inserted into the call stack. This occurs in the _PyEval_EvalFrameDefault() function. The extra frame should be invisible to all Python and most C extensions, but out-of-process profilers and debuggers need to be aware of it. These shim frames can be detected by checking frame->owner == FRAME_OWNED_BY_CSTACK.

  Extensions implementing their own interpreters using PEP 523 need to be aware of this shim frame and the changes to the semantics of RETURN_VALUE, YIELD_VALUE, and RETURN_GENERATOR, which now clear the frame.

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

• gh-98686: Quicken all code objects, and specialize adaptive bytecode instructions more aggressively.

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

• gh-91058: ImportError raised from failed from <module> import <name> now include suggestions for the value of <name> based on the available names in <module>. Patch by Pablo Galindo

• gh-96793: The FOR_ITER now leaves the iterator on the stack on termination of the loop. This is to assist specialization of loops for generators.

• gh-90716: Add _pylong.py module. It includes asymptotically faster algorithms that can be used for operations on integers with many digits. It is used by longobject.c to speed up some operations.

• gh-95389: Expose ETH_P_ALL and some of the ETHERTYPE_* constants in socket. Patch by Noam Cohen.

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

Library

• 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-94597: Deprecate asyncio.AbstractChildWatcher to be removed in Python 3.14. Patch by Kumar Aditya.

• gh-99305: Improve performance of secrets.token_hex().

• 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-92584: Remove the distutils package. It was deprecated in Python 3.10 by PEP 632 “Deprecate distutils module”. For projects still using distutils and cannot be updated to something else, the setuptools project can be installed: it still provides distutils. Patch by Victor Stinner.

• gh-98999: Now _pyio is consistent with _io in raising ValueError when executing methods over closed buffers.

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

• gh-83004: Clean up refleaks on failed module initialisation 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-98878: Use the frame bound builtins when offering a name suggestion in traceback to prevent crashing when __builtins__ is not a dict.

• gh-98139: In importlib._bootstrap, enhance namespace package repr to <module 'x' (namespace) from ['path']>.

• gh-90352: Fix _SelectorDatagramTransport to inherit from DatagramTransport in asyncio. Patch by Kumar Aditya.

• 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-98658: The array.array class now supports subscripting, making it a generic type.

• gh-98284: Improved TypeError message for undefined abstract methods of a abc.ABC instance. The names of the missing methods are surrounded by single-quotes to highlight them.

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

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

• gh-72719: Remove modules asyncore and asynchat, which were deprecated by PEP 594.

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

• gh-94172: ftplib: Remove the FTP_TLS.ssl_version class attribute: use the context parameter instead. Patch by Victor Stinner

• gh-94172: Remove the keyfile and certfile parameters from the ftplib, imaplib, poplib and smtplib modules, and the key_file, cert_file and check_hostname parameters from the http.client module, all deprecated since Python 3.6. Use the context parameter (ssl_context in imaplib) instead. Patch by Victor Stinner.

• gh-83638: Add the autocommit attribute to sqlite3.Connection and the autocommit parameter to sqlite3.connect() to control PEP 249-compliant transaction handling. Patch by Erlend E. Aasland.

• gh-92452: Fixed a race condition that could cause sysconfig.get_config_var() to incorrectly return None in multi-threaded programs.

• gh-91803: Fix an error when using a method of objects mocked with unittest.mock.create_autospec() after it was sealed with unittest.mock.seal() function.

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

• bpo-40358: Add walk_up argument in pathlib.PurePath.relative_to().

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

Documentation

• gh-98832: Changes wording of docstring for pathlib.Path.iterdir().

• gh-97966: Update uname docs to clarify the special nature of the platform attribute and to indicate when it became late-bound.

Tests

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

• 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 compiler warning in configure check for PTHREAD_SCOPE_SYSTEM.

• 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-98949: Drop unused build dependency on readelf.

• gh-98989: Use python3.11, if available, for regeneration and freezing.

• gh-98831: Add new tooling, in Tools/cases_generator, to generate the interpreter switch statement from a list of opcode definitions. This only affects adding, modifying or removing instruction definitions. The instruction definitions now live in Python/bytecodes.c, in the form of a custom DSL (under development). The tooling reads this file and writes Python/generated_cases.c.h, which is then included by Python/ceval.c to provide most of the cases of the main interpreter switch.

• gh-98817: Remove PCbuild/lib.pyproj: it’s not used for anything, is only a minor convenience for Visual Studio users (who probably mostly don’t even know about it), and it takes a lot of maintenance effort to keep updated.

• gh-98776: Fix make regen-test-levenshtein for out-of-tree 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.

Windows

• 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.

macOS

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

C API

• gh-98724: The Py_CLEAR, Py_SETREF and Py_XSETREF macros now only evaluate their argument once. If the argument has side effects, these side effects are no longer duplicated. Patch by Victor Stinner.

• 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-98410: Add getbufferproc and releasebufferproc to the stable API.

• gh-98610: Some configurable capabilities of sub-interpreters have changed. They always allow subprocesses (subprocess) now, whereas before subprocesses could be optionally disallowed for a sub-interpreter. Instead os.exec() can now be disallowed. Disallowing daemon threads is now supported. Disallowing all threads is still allowed, but is never done by default. Note that the optional restrictions are only available through _Py_NewInterpreterFromConfig(), which isn’t a public API. They do not affect the main interpreter, nor Py_NewInterpreter().

• gh-98608: A _PyInterpreterConfig has been added and _Py_NewInterpreter() has been renamed to _Py_NewInterpreterFromConfig(). The “isolated_subinterpreters” argument is now a granular config that captures the previous behavior. Note that this is all “private” API.

• 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)

• gh-91248: Add PyFrame_GetVar() and PyFrame_GetVarString() functions to get a frame variable by its name. Patch by Victor Stinner.

Python 3.12.0 alpha 1

Release date: 2022-10-25

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.

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

• gh-98461: Fix source location in bytecode for list, set and dict comprehensions as well as generator expressions.

• gh-98354: Added unicode check for name attribute of spec argument passed in _imp.create_builtin() function.

• gh-98398: Fix source location of ‘assert’ bytecodes.

• gh-98390: Fix location of sub-expressions of boolean expressions, by reducing their scope to that of the sub-expression.

• gh-98254: Modules from the standard library are now potentially suggested as part of the error messages displayed by the interpreter when an NameError is raised to the top level. Patch by Pablo Galindo

• gh-97997: Add running column offset to the tokenizer state to avoid calculating AST column information with pointer arithmetic.

• gh-97973: Modify the tokenizer to return all necessary information the parser needs to set location information in the AST nodes, so that the parser does not have to calculate those doing pointer arithmetic.

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

• gh-97955: Migrate zoneinfo to Argument Clinic.

• gh-97912: The compiler now avoids quadratic behavior when finding which instructions should use the LOAD_FAST_CHECK opcode.

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

• gh-97922: The Garbage Collector now runs only on the eval breaker mechanism of the Python bytecode evaluation loop instead on object allocations. The GC can also run when PyErr_CheckSignals() is called so C extensions that need to run for a long time without executing any Python code also have a chance to execute the GC periodically.

• gh-65961: When __package__ is different than __spec__.parent, raise a DeprecationWarning instead of ImportWarning.

  Also remove importlib.util.set_package() which was scheduled for removal.

• gh-97850: Long deprecated, module_repr() should now be completely eradicated.

• gh-86298: In cases where warnings.warn_explicit() consults the module’s loader, an DeprecationWarning is issued when m.__loader__ differs from m.__spec__.loader.

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

• gh-91052: Add API for subscribing to modification events on selected dictionaries.

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

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

• gh-97670: Remove the sys.getdxp() function and the Tools/scripts/analyze_dxp.py script. DXP stands for “dynamic execution pairs”. They were related to DYNAMIC_EXECUTION_PROFILE and DXPAIRS macros which have been removed in Python 3.11. Python can now be built with ./configure --enable-pystats to gather statistics on Python opcodes. Patch by Victor Stinner.

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

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

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

• 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-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-95778: The PyLong_FromString function was refactored to make it more maintainable and extensible.

• 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-90997: Improve the performance of reading and writing inline bytecode caches on some platforms.

• gh-96751: Remove dead code from CALL_FUNCTION_EX opcode.

• gh-90751: memoryview now supports half-floats. Patch by Donghee Na and Antoine Pitrou.

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

• gh-64373: Convert _functools to argument clinic.

• 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-90230: Fix compiler warnings and test failures when building with --enable-pystats.

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

• 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-91079: Separate Python recursion checking from C recursion checking which reduces the chance of C stack overflow and allows the recursion limit to be increased safely.

• gh-93911: Fix an issue that could prevent LOAD_ATTR from specializing properly when accessing properties.

• gh-96348: Emit a DeprecationWarning when throw(), throw() or athrow() are called with more than one argument.

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

• gh-96364: Fix text signatures of list.__getitem__ and dict.__getitem__.

• gh-96352: Fix AttributeError missing name and obj attributes in object.__getattribute__(). Patch by Philip Georgi.

• gh-93554: Change the jump opcodes so that all conditional jumps are forward jumps. Backward jumps are converted by the assembler into a conditional forward jump whose target is the fallthrough block (and with a reversed condition), followed by an unconditional backward jump. For example:

  POP_JUMP_IF_TRUE BACKWARD_TARGET becomes POP_JUMP_IF_FALSE NEXT_BLOCK; JUMP BACKWARD_TARGET.

  All the directed conditional jump opcodes were removed: POP_JUMP_FORWARD_IF_TRUE, POP_JUMP_BACKWARD_IF_TRUE, POP_JUMP_FORWARD_IF_FALSE, POP_JUMP_BACKWARD_IF_FALSE, POP_JUMP_FORWARD_IF_NONE, POP_JUMP_BACKWARD_IF_NONE, POP_JUMP_FORWARD_IF_NOT_NONE, POP_JUMP_BACKWARD_IF_NOT_NONE.

  The corresponding opcodes without direction are no longer pseudo-instructions, and they implement the forward conditional jumps.

• gh-96268: Loading a file with invalid UTF-8 will now report the broken character at the correct location.

• gh-96237: The internal field _PyInterpreterFrame.f_func is renamed to _PyInterpreterFrame.f_funcobj and may be any object. The f_globals and f_builtin fields may hold junk values.

  It is safest to treat the _PyInterpreterFrame struct as opaque.

• gh-96187: Fixed a bug that caused _PyCode_GetExtra to return garbage for negative indexes. Patch by Pablo Galindo

• gh-96143: Add a new -X perf Python command line option as well as sys.activate_stack_trampoline() and sys.deactivate_stack_trampoline() function in the sys module that allows to set/unset the interpreter in a way that the Linux perf profiler can detect Python calls. The new sys.is_stack_trampoline_active() function allows to query the state of the perf trampoline. Design by Pablo Galindo. Patch by Pablo Galindo and Christian Heimes with contributions from Gregory P. Smith [Google] and Mark Shannon.

• 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-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-93678: Added test a harness for direct unit tests of the compiler’s optimization stage. The _testinternalcapi.optimize_cfg() function runs the optimiser on a sequence of instructions. The CfgOptimizationTestCase class in test.support has utilities for invoking the optimizer and checking the output.

• gh-95245: Reduces the size of a “simple” Python object from 8 to 6 words by moving the weakreflist pointer into the pre-header directly before the object’s dict/values pointer.

• gh-90997: Compile virtual try/except blocks to handle exceptions raised during close() or throw() calls through a suspended frame.

• gh-95977: Optimized calling __get__() with vectorcall. Patch by Kumar Aditya.

• gh-91210: Improve error message when a parameter without a default value follows one with a default value, and show the same message, even when the non-default/default sequence is preceded by positional-only parameters.

• gh-95922: Fixed bug where the compiler’s eliminate_empty_basic_blocks function ignores the last block of the code unit.

• 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-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-91146: Reduce allocation size of list from str.split() and str.rsplit(). Patch by Donghee Na and Inada Naoki.

• gh-87092: Create a ‘jump target label’ abstraction in the compiler so that the compiler’s codegen stage does not work directly with basic blocks. This prepares the code for changes to the underlying CFG generation mechanism.

• 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-95245: Merge managed dict and values pointer into a single tagged pointer to save one word in the pre-header.

• gh-93678: Add cfg_builder struct and refactor the relevant code so that a cfg can be constructed without an instance of the compiler struct.

• 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-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-95023: Implement os.setns() and os.unshare() for Linux. Patch by Noam Cohen.

• gh-94036: Fix incorrect source location info for some multi-line attribute accesses and method calls.

• 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.

• 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.

• 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-94893: Fix an issue where frame object manipulations could corrupt inline bytecode caches.

• 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.

• 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-87995: types.MappingProxyType instances are now hashable if the underlying mapping is hashable.

• 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-94163: Add BINARY_SLICE and STORE_SLICE instructions for more efficient handling and better specialization of slicing operations, where the slice is explicit in the source code.

• gh-94021: Fix unreachable code warning in Python/specialize.c.

• gh-93911: Specialize LOAD_ATTR for objects with custom __getattribute__.

• gh-93955: Improve performance of attribute lookups on objects with custom __getattribute__ and __getattr__. Patch by Ken Jin.

• gh-93911: Specialize LOAD_ATTR for property() attributes.

• gh-93678: Refactor compiler optimisation code so that it no longer needs the struct assembler and struct compiler passed around. Instead, each function takes the CFG and other data that it actually needs. This will make it possible to test this code directly.

• gh-93841: When built with -enable-pystats, sys._stats_on(), sys._stats_off(), sys._stats_clear() and sys._stats_dump() functions have been added to enable gathering stats for parts of programs.

• 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-93678: Refactor the compiler to reduce boilerplate and repetition.

• 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-93621: Change order of bytecode instructions emitted for with and async with to reduce the number of entries in the exception table.

• gh-93533: Reduce the size of the inline cache for LOAD_METHOD by 2 bytes.

• gh-93444: Removed redundant fields from the compiler’s basicblock struct: b_nofallthrough, b_exit, b_return. They can be easily calculated from the opcode of the last instruction of the block.

• gh-93429: LOAD_METHOD instruction has been removed. It was merged back into LOAD_ATTR.

• 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-93359: Ensure that custom ast nodes without explicit end positions can be compiled. Patch by Pablo Galindo.

• gh-93356: Code for exception handlers is emitted at the end of the code unit’s bytecode. This avoids one jump when no exception is raised.

• 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-93283: Improve error message for invalid syntax of conversion character in f-string expressions.

• gh-93345: Fix a crash in substitution of a TypeVar in nested generic alias after TypeVarTuple.

• gh-93223: When a bytecode instruction jumps to an unconditional jump instruction, the first instruction can often be optimized to target the unconditional jump’s target directly. For tracing reasons, this would previously only occur if both instructions have the same line number. This also now occurs if the unconditional jump is artificial, i.e., if it has no associated line number.

• 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-93040: Wraps unused parameters in Objects/obmalloc.c with Py_UNUSED.

• gh-93143: Avoid NULL checks for uninitialized local variables by determining at compile time which variables must be initialized.

• 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-93012: Added the new function PyType_FromMetaclass(), which generalizes the existing PyType_FromModuleAndSpec() using an additional metaclass argument. This is useful for language binding tools, where it can be used to intercept type-related operations like subclassing or static attribute access by specifying a metaclass with custom slots.

  Importantly, PyType_FromMetaclass() is available in the Limited API, which provides a path towards migrating more binding tools onto the Stable ABI.

• gh-93021: Fix the __text_signature__ for __get__() methods implemented in C. Patch by Jelle Zijlstra.

• gh-89914: The operand of the YIELD_VALUE instruction is set to the stack depth. This is done to help frame handling on yield and may assist debuggers.

• gh-92955: Fix memory leak in code object’s lines and positions iterators as they were not finalized at exit. Patch by Kumar Aditya.

• gh-92930: Fixed a crash in _pickle.c from mutating collections during __reduce__ or persistent_id.

• gh-90690: The PRECALL instruction has been removed. It offered only a small advantage for specialization and is not needed in the vast majority of cases.

• 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 ‘:’

• 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-92777: Specialize LOAD_METHOD for objects with lazy dictionaries. Patch by Ken Jin.

• gh-92658: Add support for connecting and binding to Hyper-V sockets on Windows Hyper-V hosts and guests.

• gh-92236: Remove spurious “LINE” event when starting a generator or coroutine, visible tracing functions implemented in C.

• gh-91102: _warnings.warn_explicit() is ported to Argument Clinic.

• 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-88750: The deprecated debug build only PYTHONTHREADDEBUG environment variable no longer does anything.

• gh-92261: Fix hang when trying to iterate over a typing.Union.

• gh-91432: Specialized the FOR_ITER opcode using the PEP 659 machinery

• gh-91399: Removed duplicate ‘{0, 0, 0, 0, 0, 0}’ entry in ‘Objects/unicodetype_db.h’.

• gh-91578: Updates the error message for abstract class.

• bpo-47091: Improve performance of repetition of list and tuple by using memcpy to copy data and performing the reference increments in one step.

• 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.

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

Library

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

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

• gh-98393: The os module no longer accepts bytes-like paths, like bytearray and memoryview types: only the exact bytes type is accepted for bytes strings. Patch by Victor Stinner.

• gh-98363: Added itertools.batched() to batch data into lists of a given length with the last list possibly being shorter than the others.

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

• 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-98257: Make sys.setprofile() and sys.settrace() functions reentrant. They can no long fail with: RuntimeError("Cannot install a trace function while another trace function is being installed"). Patch by Victor Stinner.

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

• gh-94597: Deprecated asyncio.AbstractEventLoopPolicy.get_child_watcher() and asyncio.AbstractEventLoopPolicy.set_child_watcher() methods to be removed in Python 3.14. Patch by Kumar Aditya.

• 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-44098: Release the GIL when creating mmap.mmap objects on Unix.

• 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-94597: The child watcher classes MultiLoopChildWatcher, FastChildWatcher and SafeChildWatcher are deprecated and will be removed in Python 3.14. Patch by Kumar Aditya.

• gh-98023: Change default child watcher to PidfdChildWatcher on Linux systems which supports it. Patch by Kumar Aditya.

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

• gh-65961: Do not rely solely on __cached__ on modules; code will also support __spec__.cached.

• gh-97646: Replace deprecated application/javascript with text/javascript in mimetypes. See RFC 9239. Patch by Noam Cohen.

• gh-97930: Apply changes from importlib_resources 5.8 and 5.9: Traversable.joinpath provides a concrete implementation. as_file now supports directories of resources.

• gh-97850: Remove deprecated importlib.util.set_loader() and importlib.util.module_for_loader() from importlib.util.

• 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-97008: NameError and AttributeError spelling suggestions provided since gh-82711 are now also emitted by the pure Python traceback module. Tests for those suggestions now exercise both implementations to ensure they are equivalent. Patch by Carl Friedrich Bolz-Tereick and Łukasz Langa.

• gh-97799: dataclass now uses inspect.get_annotations() to examine the annotations on class objects.

• gh-97781: Removed deprecated interfaces in importlib.metadata (entry points accessed as dictionary, implicit dictionary construction of sequence of EntryPoint objects, mutablility of EntryPoints result, access of entry point by index). entry_points now has a simpler, more straightforward API (returning EntryPoints).

• 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-95534: gzip.GzipFile.read() reads 10% faster.

• 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-97545: Make Semaphore run faster.

• 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-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-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-96704: Pass the correct contextvars.Context when a asyncio exception handler is called on behalf of a task or callback handle. This adds a new Task method, get_context, and also a new Handle method with the same name. If this method is not found on a task object (perhaps because it is a third-party library that does not yet provide this method), the context prevailing at the time the exception handler is called is used.

• 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-95865: Reduce urllib.parse.quote_from_bytes() memory use on large values.

  Contributed by Dennis Sweeney.

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

• gh-96734: Update unicodedata database to Unicode 15.0.0.

• gh-96735: Fix undefined behaviour in struct.unpack().

• gh-46412: Improve performance of bool(db) for large ndb/gdb databases. Previously this would call len(db) which would iterate over all keys – the answer (empty or not) is known after the first key.

• 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-96538: Speed up bisect.bisect() functions by taking advantage of type-stability.

• gh-96465: Fraction hashes are now cached.

• gh-96079: In typing, fix missing field name and incorrect __module__ in _AnnotatedAlias.

• gh-96415: Remove types._cell_factory from module namespace.

• gh-95987: Fix repr of Any subclasses.

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

• 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-96142: Add match_args, kw_only, slots, and weakref_slot to _DataclassParams.

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

• gh-89258: Added a getChildren() method to logging.Logger, to get the immediate child loggers of a logger.

• gh-96346: Use double caching for compiled RE patterns.

• gh-96349: Fixed a minor performance regression in threading.Event.__init__()

• gh-90467: Fix asyncio.streams.StreamReaderProtocol to keep a strong reference to the created task, so that it’s not garbage collected

• gh-96172: Fix a bug in unicodedata: east_asian_width used to return the wrong value for unassigned characters; and for yet unassigned, but reserved characters.

• 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-96145: Add AttrDict to JSON module for use with object_hook.

• 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-96125: Fix incorrect condition that causes sys.thread_info.name to be wrong on pthread platforms.

• gh-96019: Fix a bug in the makeunicodedata.py script leading to about 13 KiB of space saving in the unicodedata module, specifically the character decomposition data.

• 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-69142: Add %:z strftime format code (generates tzoffset with colons as separator), see strftime() and strptime() Behavior.

• 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-95865: Speed up urllib.parse.quote_from_bytes() by replacing a list comprehension with map().

• gh-95861: Add support for computing Spearman’s correlation coefficient to the existing statistics.correlation() function.

• gh-95804: Fix logging shutdown handler so it respects MemoryHandler.flushOnClose.

• gh-95704: When a task catches asyncio.CancelledError and raises some other error, the other error should generally not silently be suppressed.

• gh-95149: The HTTPStatus enum offers a couple of properties to indicate the HTTP status category e.g. HTTPStatus.OK.is_success.

• gh-95609: Update bundled pip to 22.2.2.

• gh-95289: Fix asyncio.TaskGroup to propagate exception when asyncio.CancelledError was replaced with another exception by a context manager. Patch by Kumar Aditya and Guido van Rossum.

• gh-94909: Fix incorrect joining of relative Windows paths with drives in pathlib.PurePath initializer.

• gh-95385: Faster json.dumps() when sorting of keys is not requested (default).

• gh-83901: Improve Signature.bind error message for missing keyword-only arguments.

• gh-95339: Update bundled pip to 22.2.1.

• gh-95045: Fix GC crash when deallocating _lsprof.Profiler by untracking it before calling any callbacks. Patch by Kumar Aditya.

• 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-95097: Fix asyncio.run() for asyncio.Task implementations without uncancel() method. Patch by Kumar Aditya.

• 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-93899: Fix check for existence of os.EFD_CLOEXEC, os.EFD_NONBLOCK and os.EFD_SEMAPHORE flags on older kernel versions where these flags are not present. Patch by Kumar Aditya.

• gh-95166: Fix concurrent.futures.Executor.map() to cancel the currently waiting on future on an error - e.g. TimeoutError or KeyboardInterrupt.

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

• gh-95077: Add deprecation warning for enum member.member access (e.g. Color.RED.BLUE). Remove EnumMeta.__getattr__.

• gh-95109: Ensure that timeouts scheduled with asyncio.Timeout that have already expired are delivered promptly.

• gh-95105: wsgiref.types.InputStream.__iter__() should return Iterator[bytes], not Iterable[bytes]. Patch by Shantanu Jain.

• gh-95066: Replaced assert with exception in ast.parse(), when feature_version has an invalid major version. Patch by Shantanu Jain.

• gh-77617: Add sqlite3 command-line interface. Patch by Erlend Aasland.

• gh-95005: Replace _PyAccu with _PyUnicodeWriter in JSON encoder and StringIO and remove the _PyAccu implementation.

• gh-90085: Remove -c/--clock and -t/--time CLI options of timeit. The options had been deprecated since Python 3.3 and the functionality was removed in Python 3.7. 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-94736: Fix crash when deallocating an instance of a subclass of _multiprocessing.SemLock. Patch by Kumar Aditya.

• gh-81620: Add random.binomialvariate().

• gh-74116: Allow asyncio.StreamWriter.drain() to be awaited concurrently by multiple tasks. Patch by Kumar Aditya.

• gh-87822: When called with capture_locals=True, the traceback module functions swallow exceptions raised from calls to repr() on local variables of frames. This is in order to prioritize the original exception over rendering errors. An indication of the failure is printed in place of the missing value. (Patch by Simon-Martin Schroeder).

• 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-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-94309: Deprecate aliases typing.Hashable and typing.Sized

• gh-92546: An undocumented python -m pprint benchmark is moved into pprint suite of pyperformance. Patch by Oleg Iarygin.

• 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-94619: Remove the long-deprecated module_repr() from importlib.

• 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-94343: Allow setting the attributes of reprlib.Repr during object initialization

• gh-94382: Port static types of _multiprocessing module to heap types. Patch by Kumar Aditya.

• gh-78724: Fix crash in struct.Struct when it was not completely initialized by initializing it in __new__(). 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-94383: xml.etree: Remove the ElementTree.Element.copy() method of the pure Python implementation, deprecated in Python 3.10, use the copy.copy() function instead. The C implementation of xml.etree has no copy() method, only a __copy__() method. Patch by Victor Stinner.

• gh-94379: zipimport: Remove find_loader() and find_module() methods, deprecated in Python 3.10: use the find_spec() method instead. See PEP 451 for the rationale. Patch by Victor Stinner.

• gh-94352: shlex.split(): Passing None for s argument now raises an exception, rather than reading sys.stdin. The feature was deprecated in Python 3.9. Patch by Victor Stinner.

• gh-94318: Strip trailing spaces in pydoc text output.

• gh-89988: Fix memory leak in pickle.Pickler when looking up dispatch_table. Patch by Kumar Aditya.

• gh-90016: Deprecate sqlite3 default adapters and converters. Patch by Erlend E. Aasland.

• gh-94254: Fixed types of struct module to be immutable. Patch by Kumar Aditya.

• gh-93259: Now raise ValueError when None or an empty string are passed to Distribution.from_name (and other callers).

• gh-74696: shutil.make_archive() now passes the root_dir argument to custom archivers which support it.

• gh-94216: The dis module now has the opcodes for pseudo instructions (those which are used by the compiler during code generation but then removed or replaced by real opcodes before the final bytecode is emitted).

• gh-93096: Removed undocumented python -m codecs. Use python -m unittest test.test_codecs.EncodedFileTest instead.

• gh-94207: Made _struct.Struct GC-tracked in order to fix a reference leak in the _struct module.

• gh-93096: Removed undocumented -t argument of python -m base64. Use python -m unittest test.test_base64.LegacyBase64TestCase.test_encodebytes instead.

• gh-94226: Remove the locale.format() function, deprecated in Python 3.7: use locale.format_string() instead. Patch by Victor Stinner.

• gh-94199: Remove the ssl.match_hostname() function. The ssl.match_hostname() was deprecated in Python 3.7. OpenSSL performs hostname matching since Python 3.7, Python no longer uses the ssl.match_hostname() function. Patch by Victor Stinner.

• gh-94214: Document the context object used in the venv.EnvBuilder class, and add the new environment’s library path to it.

• gh-94199: Remove the ssl.wrap_socket() function, deprecated in Python 3.7: instead, create a ssl.SSLContext object and call its ssl.SSLContext.wrap_socket method. Any package that still uses ssl.wrap_socket() is broken and insecure. The function neither sends a SNI TLS extension nor validates server hostname. Code is subject to CWE 295 Improper Certificate Validation. Patch by Victor Stinner.

• gh-94199: Remove the ssl.RAND_pseudo_bytes() function, deprecated in Python 3.6: use os.urandom() or ssl.RAND_bytes() instead. Patch by Victor Stinner.

• gh-94199: hashlib: Remove the pure Python implementation of hashlib.pbkdf2_hmac(), deprecated in Python 3.10. Python 3.10 and newer requires OpenSSL 1.1.1 (PEP 644): this OpenSSL version provides a C implementation of pbkdf2_hmac() which is faster. Patch by Victor Stinner.

• gh-94196: gzip: Remove the filename attribute of gzip.GzipFile, deprecated since Python 2.6, use the name attribute instead. In write mode, the filename attribute added '.gz' file extension if it was not present. Patch by Victor Stinner.

• gh-94182: run the asyncio.PidfdChildWatcher on the running loop, this allows event loops to run subprocesses when there is no default event loop running on the main thread

• gh-94169: Remove io.OpenWrapper and _pyio.OpenWrapper, deprecated in Python 3.10: just use open() instead. The open() (io.open()) function is a built-in function. Since Python 3.10, _pyio.open() is also a static method. Patch by Victor Stinner.

• 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-93973: Add keyword argument all_errors to asyncio.create_connection so that multiple connection errors can be raised as an ExceptionGroup.

• gh-93963: Officially deprecate from importlib.abc classes moved to importlib.resources.abc.

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

• 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-93475: Expose FICLONE and FICLONERANGE constants in fcntl. Patch by Illia Volochii.

• gh-93370: Deprecate sqlite3.version and sqlite3.version_info.

• gh-91810: Suppress writing an XML declaration in open files in ElementTree.write() with encoding='unicode' and xml_declaration=None.

• 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-93312: Add os.PIDFD_NONBLOCK flag to open a file descriptor for a process with os.pidfd_open() in non-blocking mode. Patch by Kumar Aditya.

• gh-88123: Implement Enum.__contains__ that returns True or False to replace the deprecated behaviour that would sometimes raise a TypeError.

• gh-93297: Make asyncio task groups prevent child tasks from being GCed

• gh-85308: Changed argparse.ArgumentParser to use filesystem encoding and error handler instead of default text encoding to read arguments from file (e.g. fromfile_prefix_chars option). This change affects Windows; argument file should be encoded with UTF-8 instead of ANSI Codepage.

• gh-93156: Accessing the pathlib.PurePath.parents sequence of an absolute path using negative index values produced incorrect results.

• gh-93162: Add the ability for logging.config.dictConfig() to usefully configure QueueHandler and QueueListener as a pair, and add logging.getHandlerByName() and logging.getHandlerNames() APIs to allow access to handlers by name.

• gh-93243: The smtpd module was removed per the schedule in PEP 594.

• gh-92886: Replace assert statements with raise AssertionError() in BaseHandler so that the tested behaviour is maintained running with optimizations (-O).

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

• 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-91513: Added taskName attribute to logging module for use with asyncio tasks.

• gh-74696: shutil.make_archive() no longer temporarily changes the current working directory during creation of standard .zip or tar archives.

• 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-93033: Search in some strings (platform dependent i.e [U+0xFFFF, U+0x0100] on Windows or [U+0xFFFFFFFF, U+0x00010000] on Linux 64-bit) are now up to 10 times faster.

• 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-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-92986: Fix ast.unparse() when ImportFrom.level is None

• 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-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-92869: Added c_time_t to ctypes, which has the same size as the time_t type in C.

• 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-89325: Removed many old deprecated unittest features: