Changelog

Python 3.13.2 final

Release date: 2025-02-04

macOS

  • gh-127592: Usage of the unified Apple System Log APIs was disabled when the minimum macOS version is earlier than 10.12.

Windows

  • gh-127353: Allow to force color output on Windows using environment variables. Patch by Andrey Efremov.

Tools/Demos

  • gh-129248: The iOS test runner now strips the log prefix from each line output by the test suite.

  • gh-128152: Fix a bug where Argument Clinic’s C pre-processor parser tried to parse pre-processor directives inside C comments. Patch by Erlend Aasland.

Tests

  • gh-127906: Test the limited C API in test_cppext. Patch by Victor Stinner.

  • gh-127637: Add tests for the dis command-line interface. Patch by Bénédikt Tran.

  • gh-126925: iOS test results are now streamed during test execution, and the deprecated xcresulttool is no longer used.

Security

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

  • gh-127655: Fixed the asyncio.selector_events._SelectorSocketTransport transport not pausing writes for the protocol when the buffer reaches the high water mark when using asyncio.WriteTransport.writelines().

  • gh-126108: Fix a possible NULL pointer dereference in PySys_AddWarnOptionUnicode().

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

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

Library

  • gh-129502: Unlikely errors in preparing arguments for ctypes callback are now handled in the same way as errors raised in the callback of in converting the result of the callback – using sys.unraisablehook() instead of sys.excepthook() and not setting sys.last_exc and other variables.

  • gh-129403: Corrected ValueError message for asyncio.Barrier and threading.Barrier.

  • gh-129409: Fix an integer overflow in the csv module when writing a data field larger than 2GB.

  • gh-118761: Improve import time of subprocess by lazy importing locale and signal. Patch by Taneli Hukkinen.

  • gh-129346: In sqlite3, handle out-of-memory when creating user-defined SQL functions.

  • gh-129061: Fix FORCE_COLOR and NO_COLOR when empty strings. Patch by Hugo van Kemenade.

  • gh-128550: Removed an incorrect optimization relating to eager tasks in asyncio.TaskGroup that resulted in cancellations being missed.

  • gh-128991: Release the enter frame reference within bdb callback

  • gh-128978: Fix a NameError in sysconfig.expand_makefile_vars(). Patch by Bénédikt Tran.

  • gh-128961: Fix a crash when setting state on an exhausted array.array iterator.

  • gh-128894: Fix traceback.TracebackException._format_syntax_error not to fail on exceptions with custom metadata.

  • gh-128916: Do not attempt to set SO_REUSEPORT on sockets of address families other than AF_INET and AF_INET6, as it is meaningless with these address families, and the call with fail with Linux kernel 6.12.9 and newer.

  • gh-128679: Fix tracemalloc.stop() race condition. Fix tracemalloc to support calling tracemalloc.stop() in one thread, while another thread is tracing memory allocations. Patch by Victor Stinner.

  • gh-128636: Fix PyREPL failure when os.environ is overwritten with an invalid value.

  • gh-128562: Fix possible conflicts in generated tkinter widget names if the widget class name ends with a digit.

  • gh-128498: Default to stdout isatty for color detection instead of stderr. Patch by Hugo van Kemenade.

  • gh-128552: Fix cyclic garbage introduced by asyncio.loop.create_task() and asyncio.TaskGroup.create_task() holding a reference to the created task if it is eager.

  • gh-128479: Fix asyncio.staggered.staggered_race() leaking tasks and issuing an unhandled exception.

  • gh-128400: Fix crash when using faulthandler.dump_traceback() while other threads are active on the free threaded build.

  • gh-88834: Unify the instance check for typing.Union and types.UnionType: Union now uses the instance checks against its parameters instead of the subclass checks.

  • gh-128302: Fix xml.dom.xmlbuilder.DOMEntityResolver.resolveEntity(), which was broken by the Python 3.0 transition.

  • gh-128302: Allow xml.dom.xmlbuilder.DOMParser.parse() to correctly handle xml.dom.xmlbuilder.DOMInputSource instances that only have a systemId attribute set.

  • gh-112064: Fix incorrect handling of negative read sizes in HTTPResponse.read. Patch by Yury Manushkin.

  • gh-58956: Fixed a frame reference leak in bdb.

  • gh-128131: Completely support random access of uncompressed unencrypted read-only zip files obtained by ZipFile.open.

  • gh-112328: enum.EnumDict can now be used without resorting to private API.

  • gh-127975: Avoid reusing quote types in ast.unparse() if not needed.

  • gh-128062: Revert the font of turtledemo’s menu bar to its default value and display the shortcut keys in the correct position.

  • gh-128014: Fix resetting the default window icon by passing default='' to the tkinter method wm_iconbitmap().

  • gh-115514: Fix exceptions and incomplete writes after asyncio._SelectorTransport is closed before writes are completed.

  • gh-41872: Fix quick extraction of module docstrings from a file in pydoc. It now supports docstrings with single quotes, escape sequences, raw string literals, and other Python syntax.

  • gh-127060: Set TERM environment variable to “dumb” to disable traceback colors in IDLE, since IDLE doesn’t understand ANSI escape sequences. Patch by Victor Stinner.

  • gh-126742: Fix support of localized error messages reported by dlerror(3) and gdbm_strerror in ctypes and dbm.gnu functions respectively. Patch by Bénédikt Tran.

  • gh-127873: When -E is set, only ignore PYTHON_COLORS and not FORCE_COLOR/NO_COLOR/TERM when colourising output. Patch by Hugo van Kemenade.

  • gh-127870: Detect recursive calls in ctypes _as_parameter_ handling. Patch by Victor Stinner.

  • gh-127847: Fix the position when doing interleaved seeks and reads in uncompressed, unencrypted zip files returned by zipfile.ZipFile.open().

  • gh-127732: The platform module now correctly detects Windows Server 2025.

  • gh-126821: macOS and iOS apps can now choose to redirect stdout and stderr to the system log during interpreter configuration.

  • gh-93312: Include <sys/pidfd.h> to get os.PIDFD_NONBLOCK constant. Patch by Victor Stinner.

  • gh-83662: Add missing __class_getitem__ method to the Python implementation of functools.partial(), to make it compatible with the C version. This is mainly relevant for alternative Python implementations like PyPy and GraalPy, because CPython will usually use the C-implementation of that function.

  • gh-127586: multiprocessing.pool.Pool now properly restores blocked signal handlers of the parent thread when creating processes via either spawn or forkserver.

  • gh-98188: Fix an issue in email.message.Message.get_payload() where data cannot be decoded if the Content Transfer Encoding mechanism contains trailing whitespaces or additional junk text. Patch by Hui Liu.

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

  • gh-127096: Do not recreate unnamed section on every read in configparser.ConfigParser. Patch by Andrey Efremov.

  • gh-127196: Fix crash when dict with keys in invalid encoding were passed to several functions in _interpreters module.

  • gh-126775: Make linecache.checkcache() thread safe and GC re-entrancy safe.

  • gh-126332: Fix _pyrepl crash when entering a double CTRL-Z on an overflowing line.

  • gh-126225: getopt and optparse are no longer marked as deprecated. There are legitimate reasons to use one of these modules in preference to argparse, and none of these modules are at risk of being removed from the standard library. Of the three, argparse remains the recommended default choice, unless one of the concerns noted at the top of the optparse module documentation applies.

  • gh-125553: Fix round-trip invariance for backslash continuations in tokenize.untokenize().

  • gh-123987: Fixed issue in NamespaceReader where a non-path item in a namespace path, such as a sentinel added by an editable installer, would break resource loading.

  • gh-123401: The http.cookies module now supports parsing obsolete RFC 850 date formats, in accordance with RFC 9110 requirements. Patch by Nano Zheng.

  • gh-122431: readline.append_history_file() now raises a ValueError when given a negative value.

  • gh-119257: Show tab completions menu below the current line, which results in less janky behaviour, and fixes a cursor movement bug. Patch by Daniel Hollas

Documentation

Core and Builtins

  • gh-129345: Fix null pointer dereference in syslog.openlog() when an audit hook raises an exception.

  • gh-129093: Fix f-strings such as f'{expr=}' sometimes not displaying the full expression when the expression contains !=.

  • gh-124363: Treat debug expressions in f-string as raw strings. Patch by Pablo Galindo

  • gh-128799: Add frame of except* to traceback when it wraps a naked exception.

  • gh-128078: Fix a SystemError when using anext() with a default tuple value. Patch by Bénédikt Tran.

  • gh-128717: Fix a crash when setting the recursion limit while other threads are active on the free threaded build.

  • gh-128330: Restore terminal control characters on REPL exit.

  • gh-128079: Fix a bug where except* does not properly check the return value of an ExceptionGroup’s split() function, leading to a crash in some cases. Now when split() returns an invalid object, except* raises a TypeError with the original raised ExceptionGroup object chained to it.

  • gh-128030: Avoid error from calling PyModule_GetFilenameObject on a non-module object when importing a non-existent symbol from a non-module object.

  • gh-127903: Objects/unicodeobject.c: fix a crash on DEBUG builds in _copy_characters when there is nothing to copy.

  • gh-127599: Fix statistics for increments of object reference counts (in particular, when a reference count was increased by more than 1 in a single operation).

  • gh-127651: When raising ImportError for missing symbols in from imports, use __file__ in the error message if __spec__.origin is not a location

  • gh-127582: Fix non-thread-safe object resurrection when calling finalizers and watcher callbacks in the free threading build.

  • gh-127434: The iOS compiler shims can now accept arguments with spaces.

  • gh-127536: Add missing locks around some list assignment operations in the free threading build.

  • gh-126862: Fix a possible overflow when a class inherits from an absurd number of super-classes. Reported by Valery Fedorenko. Patch by Bénédikt Tran.

  • gh-127349: Fixed the error when resizing terminal in Python REPL. Patch by Semyon Moroz.

  • gh-126076: Relocated objects such as tuple, bytes and str objects are properly tracked by tracemalloc and its associated hooks. Patch by Pablo Galindo.

C API

Build

  • gh-129539: Don’t redefine EX_OK when the system has the sysexits.h header.

  • gh-128472: Skip BOLT optimization of functions using computed gotos, fixing errors on build with LLVM 19.

  • gh-123925: Fix building the curses module on platforms with libncurses but without libncursesw.

  • gh-128321: Set LIBS instead of LDFLAGS when checking if sqlite3 library functions are available. This fixes the ordering of linked libraries during checks, which was incorrect when using a statically linked libsqlite3.

  • gh-127865: Fix build failure on systems without thread-locals support.

Python 3.13.1 final

Release date: 2024-12-03

macOS

  • gh-124448: Update bundled Tcl/Tk in macOS installer to 8.6.15.

Windows

  • gh-126911: Update credits command output.

  • gh-118973: Ensures the experimental free-threaded install includes the _tkinter module. The optional Tcl/Tk component must also be installed in order for the module to work.

  • gh-126497: Fixes venv failure due to missing redirector executables in experimental free-threaded installs.

  • gh-126074: Removed unnecessary DLLs from Windows embeddable package

  • gh-125315: Avoid crashing in platform due to slow WMI calls on some Windows machines.

  • gh-126084: Fix venvwlauncher to launch pythonw instead of python so no extra console window is created.

  • gh-125842: Fix a SystemError when sys.exit() is called with 0xffffffff on Windows.

  • gh-125550: Enable the Python Launcher for Windows to detect Python 3.14 installs from the Windows Store.

  • gh-124448: Updated bundled Tcl/Tk to 8.6.15.

Tools/Demos

  • gh-126807: Fix extraction warnings in pygettext.py caused by mistaking function definitions for function calls.

  • gh-126167: The iOS testbed was modified so that it can be used by third-party projects for testing purposes.

Tests

  • gh-126909: Fix test_os extended attribute tests to work on filesystems with 1 KiB xattr size limit.

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

  • gh-124295: Add translation tests to the argparse module.

Security

  • gh-126623: Upgrade libexpat to 2.6.4

  • gh-125140: Remove the current directory from sys.path when using PyREPL.

  • 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-127321: pdb.set_trace() will not stop at an opcode that does not have an associated line number anymore.

  • gh-127303: Publicly expose EXACT_TOKEN_TYPES in token.__all__.

  • gh-123967: Fix faulthandler for trampoline frames. If the top-most frame is a trampoline frame, skip it. Patch by Victor Stinner.

  • gh-127182: Fix io.StringIO.__setstate__() crash, when None was passed as the first value.

  • gh-127217: Fix urllib.request.pathname2url() for paths starting with multiple slashes on Posix.

  • gh-127035: Fix shutil.which on Windows. Now it looks at direct match if and only if the command ends with a PATHEXT extension or X_OK is not in mode. Support extensionless files if “.” is in PATHEXT. Support PATHEXT extensions that end with a dot.

  • gh-122273: Support PyREPL history on Windows. Patch by devdanzin and Victor Stinner.

  • gh-127078: Fix issue where urllib.request.url2pathname() failed to discard an extra slash before a UNC drive in the URL path on Windows.

  • gh-126766: Fix issue where urllib.request.url2pathname() failed to discard any ‘localhost’ authority present in the URL.

  • gh-127065: Fix crash when calling a operator.methodcaller() instance from multiple threads in the free threading build.

  • gh-126997: Fix support of STRING and GLOBAL opcodes with non-ASCII arguments in pickletools. pickletools.dis() now outputs non-ASCII bytes in STRING, BINSTRING and SHORT_BINSTRING arguments as escaped (\xXX).

  • gh-126316: grp: Make grp.getgrall() thread-safe by adding a mutex. Patch by Victor Stinner.

  • gh-126618: Fix the representation of itertools.count objects when the count value is sys.maxsize.

  • gh-85168: Fix issue where urllib.request.url2pathname() and pathname2url() always used UTF-8 when quoting and unquoting file URIs. They now use the filesystem encoding and error handler.

  • gh-67877: Fix memory leaks when regular expression matching terminates abruptly, either because of a signal or because memory allocation fails.

  • gh-126789: Fixed the values of sysconfig.get_config_vars(), sysconfig.get_paths(), and their siblings when the site initialization happens after sysconfig has built a cache for sysconfig.get_config_vars().

  • gh-126188: Update bundled pip to 24.3.1

  • gh-126780: Fix os.path.normpath() for drive-relative paths on Windows.

  • gh-126766: Fix issue where urllib.request.url2pathname() failed to discard two leading slashes introducing an empty authority section.

  • gh-126727: locale.nl_langinfo(locale.ERA) now returns multiple era description segments separated by semicolons. Previously it only returned the first segment on platforms with Glibc.

  • gh-126699: Allow collections.abc.AsyncIterator to be a base for Protocols.

  • gh-126654: Fix crash when non-dict was passed to several functions in _interpreters module.

  • gh-104745: Limit starting a patcher (from unittest.mock.patch() or unittest.mock.patch.object()) more than once without stopping it

  • gh-126595: Fix a crash when instantiating itertools.count with an initial count of sys.maxsize on debug builds. Patch by Bénédikt Tran.

  • gh-120423: Fix issue where urllib.request.pathname2url() mishandled Windows paths with embedded forward slashes.

  • gh-126565: Improve performances of zipfile.Path.open() for non-reading modes.

  • gh-126505: Fix bugs in compiling case-insensitive regular expressions with character classes containing non-BMP characters: upper-case non-BMP character did was ignored and the ASCII flag was ignored when matching a character range whose upper bound is beyond the BMP region.

  • gh-117378: Fixed the multiprocessing "forkserver" start method forkserver process to correctly inherit the parent’s sys.path during the importing of multiprocessing.set_forkserver_preload() modules in the same manner as sys.path is configured in workers before executing work items.

    This bug caused some forkserver module preloading to silently fail to preload. This manifested as a performance degration in child processes when the sys.path was required due to additional repeated work in every worker.

    It could also have a side effect of "" remaining in sys.path during forkserver preload imports instead of the absolute path from os.getcwd() at multiprocessing import time used in the worker sys.path.

    The sys.path differences between phases in the child process could potentially have caused preload to import incorrect things from the wrong location. We are unaware of that actually having happened in practice.

  • gh-125679: The multiprocessing.Lock and multiprocessing.RLock repr values no longer say “unknown” on macOS.

  • gh-126476: Raise calendar.IllegalMonthError (now a subclass of IndexError) for calendar.month() when the input month is not correct.

  • gh-126489: The Python implementation of pickle no longer calls pickle.Pickler.persistent_id() for the result of persistent_id().

  • gh-126313: Fix an issue in curses.napms() when curses.initscr() has not yet been called. Patch by Bénédikt Tran.

  • gh-126303: Fix pickling and copying of os.sched_param objects.

  • gh-126138: Fix a use-after-free crash on asyncio.Task objects whose underlying coroutine yields an object that implements an evil __getattribute__(). Patch by Nico Posada.

  • gh-126220: Fix crash in cProfile.Profile and _lsprof.Profiler when their callbacks were directly called with 0 arguments.

  • gh-126212: Fix issue where urllib.request.pathname2url() and url2pathname() removed slashes from Windows DOS drive paths and URLs.

  • gh-126223: Raise a UnicodeEncodeError instead of a SystemError upon calling _interpreters.create() with an invalid Unicode character.

  • gh-126205: Fix issue where urllib.request.pathname2url() generated URLs beginning with four slashes (rather than two) when given a Windows UNC path.

  • gh-126105: Fix a crash in ast when the ast.AST._fields attribute is deleted.

  • gh-126106: Fixes a possible NULL pointer dereference in ssl.

  • gh-126080: Fix a use-after-free crash on asyncio.Task objects for which the underlying event loop implements an evil __getattribute__(). Reported by Nico-Posada. Patch by Bénédikt Tran.

  • gh-126083: Fixed a reference leak in asyncio.Task objects when reinitializing the same object with a non-None context. Patch by Nico Posada.

  • gh-125984: Fix use-after-free crashes on asyncio.Future objects for which the underlying event loop implements an evil __getattribute__(). Reported by Nico-Posada. Patch by Bénédikt Tran.

  • gh-125969: Fix an out-of-bounds crash when an evil asyncio.loop.call_soon() mutates the length of the internal callbacks list. Patch by Bénédikt Tran.

  • gh-125966: Fix a use-after-free crash in asyncio.Future.remove_done_callback(). Patch by Bénédikt Tran.

  • gh-125789: Fix possible crash when mutating list of callbacks returned by asyncio.Future._callbacks. It now always returns a new copy in C implementation _asyncio. Patch by Kumar Aditya.

  • gh-124452: Fix an issue in email.policy.EmailPolicy.header_source_parse() and email.policy.Compat32.header_source_parse() that introduced spurious leading whitespaces into header values when the header includes a newline character after the header name delimiter (:) and before the value.

  • gh-125884: Fixed the bug for pdb where it can’t set breakpoints on functions with certain annotations.

  • gh-125355: Fix several bugs in argparse.ArgumentParser.parse_intermixed_args().

    • The parser no longer changes temporarily during parsing.

    • Default values are not processed twice.

    • Required mutually exclusive groups containing positional arguments are now supported.

    • The missing arguments report now includes the names of all required optional and positional arguments.

    • Unknown options can be intermixed with positional arguments in parse_known_intermixed_args().

  • gh-125666: Avoid the exiting the interpreter if a null byte is given as input in the new REPL.

  • gh-125710: [Enum] fix hashable<->nonhashable comparisons for member values

  • gh-125631: Restore ability to set persistent_id and persistent_load attributes of instances of the Pickler and Unpickler classes in the pickle module.

  • gh-125378: Fixed the bug in pdb where after a multi-line command, an empty line repeats the first line of the multi-line command, instead of the full command.

  • gh-125682: Reject non-ASCII digits in the Python implementation of json.loads() conforming to the JSON specification.

  • gh-125660: Reject invalid unicode escapes for Python implementation of json.loads().

  • gh-125259: Fix the notes removal logic for errors thrown in enum initialization.

  • gh-125590: Allow FrameLocalsProxy to delete and pop if the key is not a fast variable.

  • gh-125519: Improve traceback if importlib.reload() is called with an object that is not a module. Patch by Alex Waygood.

  • gh-125451: Fix deadlock when concurrent.futures.ProcessPoolExecutor shuts down concurrently with an error when feeding a job to a worker process.

  • gh-125422: Fixed the bug where pdb and bdb can step into the bottom caller frame.

  • gh-100141: Fixed the bug where pdb will be stuck in an infinite loop when debugging an empty file.

  • gh-125115: Fixed a bug in pdb where arguments starting with - can’t be passed to the debugged script.

  • 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-125398: Fix the conversion of the VIRTUAL_ENV path in the activate script in venv when running in Git Bash for Windows.

  • gh-125316: Fix using functools.partial() as enum.Enum member. A FutureWarning with suggestion to use enum.member() is now emitted when the partial instance is used as an enum member.

  • gh-125245: Fix race condition when importing collections.abc, which could incorrectly return an empty module.

  • gh-125243: Fix data race when creating zoneinfo.ZoneInfo objects in the free threading build.

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

  • gh-125235: Keep tkinter TCL paths in venv pointing to base installation on Windows.

  • 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-52551: Fix encoding issues in time.strftime(), the strftime() method of the datetime classes datetime, date and time and formatting of these classes. Characters not encodable in the current locale are now acceptable in the format string. Surrogate pairs and sequence of surrogatescape-encoded bytes are no longer recombinated. Embedded null character no longer terminates the format string.

  • 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 parser resulted in arguments to the former object’s initializer being joined by the latter object’s parser.

  • gh-125096: If the PYTHON_BASIC_REPL environment variable is set, the site module no longer imports the _pyrepl module. Moreover, the site module now respects -E and -I command line options: ignore PYTHON_BASIC_REPL in this case. Patch by Victor Stinner.

  • gh-124969: Fix locale.nl_langinfo(locale.ALT_DIGITS) on platforms with glibc. Now it returns a string consisting of up to 100 semicolon-separated symbols (an empty string in most locales) on all Posix platforms. Previously it only returned the first symbol or an empty string.

  • gh-124960: Fix support for the barry_as_FLUFL future flag in the new REPL.

  • gh-124984: Fixed thread safety in ssl in the free-threaded build. OpenSSL operations are now protected by a per-object lock.

  • gh-124958: Fix refcycles in exceptions raised from asyncio.TaskGroup and the python implementation of asyncio.Future

  • 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 3.13.0.

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

  • gh-124858: Fix reference cycles left in tracebacks in asyncio.open_connection() when used with happy_eyeballs_delay

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

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

  • 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-124594: All asyncio REPL prompts run in the same context. Contributed by Bartosz Sławecki.

  • 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-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-58956: Fixed a bug in pdb where sometimes the breakpoint won’t trigger if it was set on a function which is already in the call stack.

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

  • gh-124008: Fix possible crash (in debug build), incorrect output or returning incorrect value from raw binary write() when writing to console on Windows.

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

  • gh-122765: Fix unbalanced quote errors occurring when activate.csh in venv was sourced with a custom prompt containing unpaired quotes or newlines.

  • gh-123370: Fix the canvas not clearing after running turtledemo clock.

  • 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-120754: Update unbounded read calls in zipfile to specify an explicit size putting a limit on how much data they may read. This also updates handling around ZIP max comment size to match the standard instead of reading comments that are one byte too long.

  • gh-70764: Fixed an issue where inspect.getclosurevars() would incorrectly classify an attribute name as a global variable when the name exists both as an attribute name and a global variable.

  • gh-118289: posixpath.realpath() now raises NotADirectoryError when strict mode is enabled and a non-directory path with a trailing slash is supplied.

  • gh-119826: Always return an absolute path for os.path.abspath() on Windows.

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

  • gh-101955: Fix SystemError when match regular expression pattern containing some combination of possessive quantifier, alternative and capture group.

  • gh-88110: Fixed multiprocessing.Process reporting a .exitcode of 1 even on success when using the "fork" start method while using a concurrent.futures.ThreadPoolExecutor.

  • gh-71936: Fix a race condition in multiprocessing.pool.Pool.

  • bpo-46128: Strip unittest.IsolatedAsyncioTestCase stack frames from reported stacktraces.

  • 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-126622: Added stub pages for removed modules explaining their removal, where to find replacements, and linking to the last Python version that supported them. Contributed by Ned Batchelder.

  • gh-125277: Require Sphinx 7.2.6 or later to build the Python documentation. Patch by Adam Turner.

  • gh-124872: Added definitions for context, current context, and context management protocol, updated related definitions to be consistent, and expanded the documentation for contextvars.Context.

  • 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.

  • gh-70870: Clarified the dual usage of the term “free variable” (both the formal meaning of any reference to names defined outside the local scope, and the narrower pragmatic meaning of nonlocal variables named in co_freevars).

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

  • gh-60712: Include the object type in the lists of documented types. Change by Furkan Onder and Martin Panter.

  • bpo-34008: The Py_Main() documentation moved from the “Very High Level API” section to the “Initialization and Finalization” section.

    Also make it explicit that we expect Py_Main to typically be called instead of Py_Initialize rather than after it (since Py_Main makes its own call to Py_Initialize). Document that calling both is supported but is version dependent on which settings will be applied correctly.

Core and Builtins

  • gh-113841: Fix possible undefined behavior division by zero in complex’s _Py_c_pow().

  • gh-127020: Fix a crash in the free threading build when PyCode_GetCode(), PyCode_GetVarnames(), PyCode_GetCellvars(), or PyCode_GetFreevars() were called from multiple threads at the same time.

  • gh-126980: Fix __buffer__() of bytearray crashing when READ or WRITE are passed as flags.

  • gh-126881: Fix crash in finalization of dtoa state. Patch by Kumar Aditya.

  • gh-126341: Now ValueError is raised instead of SystemError when trying to iterate over a released memoryview object.

  • gh-126688: Fix a crash when calling os.fork() on some operating systems, including SerenityOS.

  • gh-126066: Fix importlib to not write an incomplete .pyc files when a ulimit or some other operating system mechanism is preventing the write to go through fully.

  • gh-126312: Fix crash during garbage collection on an object frozen by gc.freeze() on the free-threaded build.

  • gh-126139: Provide better error location when attempting to use a future statement with an unknown future feature.

  • gh-126018: Fix a crash in sys.audit() when passing a non-string as first argument and Python was compiled in debug mode.

  • gh-125942: On Android, the errors setting of sys.stdout was changed from surrogateescape to backslashreplace.

  • gh-125859: Fix a crash in the free threading build when gc.get_objects() or gc.get_referrers() is called during an in-progress garbage collection.

  • gh-125703: Correctly honour tracemalloc hooks in specialized Py_DECREF paths. Patch by Pablo Galindo

  • gh-125593: Use color to highlight error locations in traceback from exception group

  • gh-125444: Fix illegal instruction for older Arm architectures. Patch by Diego Russo, testing by Ross Burton.

  • gh-124375: Fix a crash in the free threading build when the GC runs concurrently with a new thread starting.

  • gh-125221: Fix possible race condition when calling __reduce_ex__() for the first time in the free threading build.

  • gh-125038: Fix crash when iterating over a generator expression after direct changes on gi_frame.f_locals. Patch by Mikhail Efimov.

  • 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.

  • gh-116510: Fix a crash caused by immortal interned strings being shared between sub-interpreters that use basic single-phase init. In that case, the string can be used by an interpreter that outlives the interpreter that created and interned it. For interpreters that share obmalloc state, also share the interned dict with the main interpreter.

  • gh-122878: Use the pager binary, if available (e.g. on Debian and derivatives), to display REPL help().

  • 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-123930: Improve the error message when a script shadowing a module from the standard library causes ImportError to be raised during a “from” import. Similarly, improve the error message when a script shadowing a third party module attempts to “from” import an attribute from that third party module while still initialising.

  • gh-122907: Building with HAVE_DYNAMIC_LOADING now works as well as it did in 3.12. Existing deficiences will be addressed separately. (See https://github.com/python/cpython/issues/122950.)

  • gh-118950: Fix bug where SSLProtocol.connection_lost wasn’t getting called when OSError was thrown on writing to socket.

  • gh-113570: Fixed a bug in reprlib.repr where it incorrectly called the repr method on shadowed Python built-in types.

  • gh-109746: If _thread.start_new_thread() fails to start a new thread, it deletes its state from interpreter and thus avoids its repeated cleanup on finalization.

C API

  • gh-126554: Fix error handling in ctypes.CDLL objects which could result in a crash in rare situations.

  • gh-125608: Fix a bug where dictionary watchers (e.g., PyDict_Watch()) on an object’s attribute dictionary (__dict__) were not triggered when the object’s attributes were modified.

  • bpo-34008: Added Py_IsInitialized to the list of APIs that are safe to call before the interpreter is initialized, and updated the embedding tests to cover it.

Build

  • gh-123877: Set wasm32-wasip1 as the WASI target. The old wasm32-wasi target is deprecated so it can be used for an eventual WASI 1.0.

  • gh-89640: Hard-code float word ordering as little endian on WASM.

  • gh-125940: The Android build now supports 16 KB page sizes.

  • gh-89640: Improve detection of float word ordering on Linux when link-time optimizations are enabled.

  • gh-125269: Fix detection of whether -latomic is needed when cross-compiling CPython using the configure script.

  • gh-121634: Allow for specifying the target compile triple for WASI.

  • gh-122578: Use WASI SDK 24 for testing.

  • gh-115382: Fix cross compile failures when the host and target SOABIs match.

Python 3.13.0 final

Release date: 2024-10-07

Core and Builtins

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

  • gh-124871: Fix compiler bug (in some versions of 3.13) where an assertion fails during reachability analysis.

Python 3.13.0 release candidate 3

Release date: 2024-10-01

macOS

  • gh-123797: Check for runtime availability of ptsname_r function on macos.

Windows

  • gh-124609: Fix _Py_ThreadId for Windows builds using MinGW. Patch by Tony Roberts.

  • gh-124254: Ensures experimental free-threaded binaries remain installed when updating.

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

Tests

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

Library

IDLE

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

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

Documentation

  • gh-124720: Update “Using Python on a Mac” section of the “Python Setup and Usage” document and include information on installing free-threading support.

  • gh-116622: Add an Android platform guide, and flag modules not available on Android.

Core and Builtins

  • gh-124567: Revert the incremental GC (in 3.13), since it’s not clear the benefits outweigh the costs at this point.

  • gh-124642: Fixed scalability issue in free-threaded builds for lock-free reads from dictionaries in multi-threaded scenarios

  • 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-124547: When deallocating an object with inline values whose __dict__ is still live: if memory allocation for the inline values fails, clear the dictionary. Prevents an interpreter crash.

  • gh-124513: Fix a crash in FrameLocalsProxy constructor: check the number of arguments. Patch by Victor Stinner.

  • gh-124442: Fix nondeterminism in compilation by sorting the value of __static_attributes__. Patch by kp2pml30.

  • gh-123856: Fix PyREPL failure when a keyboard interrupt is triggered after using a history search

  • gh-65961: Document the deprecation of setting and using __package__ and __cached__.

  • gh-124027: Support <page up>, <page down>, and <delete> keys in the Python REPL when $TERM is set to vt100.

  • 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-123339: Setting the __module__ attribute for a class now removes the __firstlineno__ item from the type’s dict, so they will no longer be inconsistent.

C API

  • gh-124160: Fix crash when importing modules containing state and single-phase initialization in a subinterpreter.

  • gh-123880: Fixed a bug that prevented circular imports of extension modules that use single-phase initialization.

Build

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

  • gh-124043: Building using --with-trace-refs is (temporarily) disallowed when the GIL is disabled.

Python 3.13.0 release candidate 2

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

  • 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-119727: Add --single-process command line option to Python test runner (regrtest). Patch by Victor Stinner.

  • 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

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-120221: asyncio REPL is now again properly recognizing KeyboardInterrupts. Display of exceptions raised in secondary threads is fixed.

  • gh-119310: Allow the new interactive shell to read history files written with the editline library that use unicode-escaped entries. Patch by aorcajo and Łukasz Langa.

  • gh-123572: Fix key mappings for various F-keys in Windows for the new REPL. Patch by devdanzin

  • gh-119034: Change <page up> and <page down> keys of the Python REPL to history search forward/backward. Patch by Victor Stinner.

  • gh-123545: Fix a double decref in rare cases on experimental JIT builds.

  • gh-123484: Fix _Py_DebugOffsets for long objects to be relative to the start of the object rather than the start of a subobject.

  • gh-123344: Add AST optimizations for type parameter defaults.

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

  • gh-123177: Fix a bug causing stray prompts to appear in the middle of wrapped lines in the new REPL.

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

  • gh-123275: Support -X gil=1 and PYTHON_GIL=1 on non-free-threaded builds.

  • gh-123177: Deactivate line wrap in the Apple Terminal via a ANSI escape code. Patch by Pablo Galindo

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

  • gh-122298: Restore printout of GC stats when gc.set_debug(gc.DEBUG_STATS) is called. This featue was accidentally removed when implementing incremental GC.

  • gh-121804: Correctly show error locations when a SyntaxError is raised in the basic REPL. Patch by Sergey B Kirpichev.

  • 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-123123: Fix displaying SyntaxError exceptions covering multiple lines. Patch by Pablo Galindo

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

  • gh-123022: Fix crash in free-threaded build when calling Py_Initialize() from a non-main thread.

  • gh-122888: Fix crash on certain calls to str() with positional arguments of the wrong type. Patch by Jelle Zijlstra.

  • gh-116622: Fix Android stdout and stderr messages being truncated or lost.

  • 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-122445: Add only fields which are modified via self.* to __static_attributes__.

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

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

  • gh-120097: FrameLocalsProxy now subclasses collections.abc.Mapping and can be matched as a mapping in match statements

C API

Build

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

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

  • gh-116622: Rename build variable MODULE_LDFLAGS back to LIBPYTHON, as it’s used by package build systems (e.g. Meson).

  • gh-118943: Fix an issue where the experimental JIT could be built several times by the make regen-all target, leading to possible race conditions on heavily parallelized builds.

  • gh-118943: Fix a possible race condition affecting parallel builds configured with --enable-experimental-jit, in which FileNotFoundError could be caused by another process already moving jit_stencils.h.new to jit_stencils.h.

Python 3.13.0 release candidate 1

Release date: 2024-07-31

Tests

Security

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

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

  • gh-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 events in question are cpython.run_stdin and cpython.run_startup.

Library

IDLE

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

Core and Builtins

  • gh-116090: Fix an issue in JIT builds that prevented some for loops from correctly firing RAISE monitoring events.

  • 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-120906: frame.f_locals now supports arbitrary hashable objects as keys.

  • 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-118934: Make PyEval_GetLocals return borrowed reference

C API

  • gh-116622: Make PyObject_Print work around a bug in Android and OpenBSD which prevented it from throwing an exception when trying to write to a read-only stream.

  • gh-121489: Export private _PyBytes_Join() again.

Build

Python 3.13.0 beta 4

Release date: 2024-07-18

Tests

  • 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.

Library

  • gh-57141: The shallow argument to filecmp.dircmp (new in Python 3.13) is now keyword-only.

  • gh-121245: Simplify handling of the history file in site.register_readline() helper. The CAN_USE_PYREPL variable now will be initialized, when imported. Patch by Sergey B Kirpichev.

  • gh-121332: Fix constructor of ast nodes with custom _attributes. Previously, passing custom attributes would raise a DeprecationWarning. Passing arguments to the constructor that are not in _fields or _attributes remains deprecated. Patch by Jelle Zijlstra.

  • gh-121279: Avoid NameError for the warnings module when accessing the depracated atributes of the importlib.abc module.

  • gh-121245: Fix a bug in the handling of the command history of the new REPL that caused the history file to be wiped at REPL exit.

  • gh-87744: Fix waitpid race while calling send_signal() in asyncio. Patch by Kumar Aditya.

  • gh-121018: Fixed other issues where argparse.ArgumentParser did not honor exit_on_error=False.

  • gh-120678: Fix regression in the new REPL that meant that globals from files passed using the -i argument would not be included in the REPL’s global namespace. Patch by Alex Waygood.

  • gh-120782: Fix wrong references of the datetime types after reloading the module.

  • gh-120713: datetime.datetime.strftime() now 0-pads years with less than four digits for the format specifiers %Y and %G on Linux. Patch by Ben Hsing

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

  • 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-118714: Allow restart in post-mortem debugging of pdb. Removed restart message when the user quits pdb from post-mortem mode.

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

IDLE

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

Documentation

Core and Builtins

  • gh-121860: Fix crash when rematerializing a managed dictionary after it was deleted.

  • gh-121814: Fixed the SegFault when PyEval_SetTrace() is used with no Python frame on stack.

  • gh-121295: Fix PyREPL console getting into a blocked state after interrupting a long paste

  • gh-121794: Fix bug in free-threaded Python where a resurrected object could lead to a negative ref count assertion failure.

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

  • gh-121609: Fix pasting of characters containing unicode character joiners in the new REPL. Patch by Marta Gomez Macias

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

  • gh-121499: Fix a bug affecting how multi-line history was being rendered in the new REPL after interacting with the new screen cache. Patch by Pablo Galindo

  • gh-121497: Fix a bug that was preventing the REPL to correctly respect the history when an input hook was set. Patch by Pablo Galindo

  • gh-121012: Tier 2 execution now ensures that list iterators remain exhausted, once they become exhausted.

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

  • gh-121368: Fix race condition in _PyType_Lookup in the free-threaded build due to a missing memory fence. This could lead to _PyType_Lookup returning incorrect results on arm64.

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

  • gh-121115: PyLong_AsNativeBytes() no longer uses __index__() methods by default. The Py_ASNATIVEBYTES_ALLOW_INDEX flag has been added to allow it.

C API

Build

  • gh-120371: Support WASI SDK 22 by explicitly skipping functions that are just stubs in wasi-libc.

  • gh-121731: Fix mimalloc compile error on GNU/Hurd

  • gh-121487: Fix deprecation warning for ATOMIC_VAR_INIT in mimalloc.

  • gh-121467: Fix a Makefile bug that prevented mimalloc header files from being installed.

  • gh-121103: On POSIX systems, excluding macOS framework installs, the lib directory for the free-threaded build now includes a “t” suffix to avoid conflicts with a co-located default build installation.

  • gh-120831: The default minimum iOS version was increased to 13.0.

  • gh-113565: Improve curses and curses.panel dependency checks in configure.

Python 3.13.0 beta 3

Release date: 2024-06-27

Core and Builtins

  • gh-120838: Py_Finalize() and Py_FinalizeEx() now always run with the main interpreter active.

  • gh-113433: Subinterpreters now get cleaned up automatically during runtime finalization.

  • gh-119462: Make sure that invariants of type versioning are maintained: * Superclasses always have their version number assigned before subclasses * The version tag is always zero if the tag is not valid. * The version tag is always non-zero if the tag is valid.

  • gh-120437: Fix _CHECK_STACK_SPACE optimization problems introduced in gh-118322.

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

  • gh-120367: Fix bug where compiler creates a redundant jump during pseudo-op replacement. Can only happen with a synthetic AST that has a try on the same line as the instruction following the exception handler.

  • 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.

  • 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-120367: Fix crash in compiler on code with redundant NOPs and JUMPs which show up after exception handlers are moved to the end of the code.

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

  • gh-120400: Support Linux perf profiler to see Python calls on RISC-V architecture.

  • gh-120221: Deliver real signals on Ctrl-C and Ctrl-Z in the new REPL. Patch by Pablo Galindo

  • gh-120346: Respect PYTHON_BASIC_REPL when running in interative inspect mode (python -i). Patch by Pablo Galindo

  • 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__.

  • gh-120225: Fix crash in compiler on empty block at end of exception handler.

  • gh-119933: Improve SyntaxError messages for invalid expressions in a type parameters bound, a type parameter constraint tuple or a default type parameter. Patch by Bénédikt Tran.

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

Library

Build

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

  • gh-120602: Correctly handle LLVM installs with LLVM_VERSION_SUFFIX when building with --enable-experimental-jit.

  • gh-120326: On Windows, fix build error when --disable-gil and --experimental-jit options are combined.

  • gh-120291: Make the python-config shell script compatible with non-bash shells.

C API

  • gh-120642: Remove the private _Py_CODEUNIT type from the public C API. The internal pycore_code.h header should now be used to get this internal type. Patch by Victor Stinner.

  • gh-120858: PyDict_Next() no longer locks the dictionary in the free-threaded build. The locking needs to be done by the caller around the entire iteration loop.

  • gh-120642: Remove the following unstable functions:

    • PyUnstable_Replace_Executor()

    • PyUnstable_SetOptimizer()

    • PyUnstable_GetOptimizer()

    • PyUnstable_GetExecutor()

    • PyUnstable_Optimizer_NewCounter()

    • PyUnstable_Optimizer_NewUOpOptimizer()

    Patch by Victor Stinner.

  • gh-119344: The critical section API is now public as part of the non-limited C API.

  • gh-118789: Add PyUnstable_Object_ClearWeakRefsNoCallbacks(), which clears weakrefs without calling their callbacks.

  • gh-117511: Make the PyMutex public in the non-limited C API.

Python 3.13.0 beta 2

Release date: 2024-06-05

Security

  • gh-118773: Fixes creation of ACLs in os.mkdir() on Windows to work correctly on non-English machines.

  • 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.

Core and Builtins

  • gh-119724: Reverted improvements to error messages for elif/else statements not matching any valid statements, which made in hard to locate the syntax errors inside those elif/else blocks.

  • gh-119842: Honor PyOS_InputHook() in the new REPL. Patch by Pablo Galindo

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

  • gh-119548: Add a clear command to the REPL. Patch by Pablo Galindo

  • gh-111999: Fix the signature of str.format_map().

  • gh-119560: An invalid assert in beta 1 has been removed. The assert would fail if PyState_FindModule() was used in an extension module’s init function before the module def had been initialized.

  • gh-119369: Fix deadlock during thread deletion in free-threaded build, which could occur when the GIL was enabled at runtime.

  • gh-119525: Fix deadlock involving _PyType_Lookup() cache in the free-threaded build when the GIL is dynamically enabled at runtime.

  • 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-118692: Avoid creating unnecessary StopIteration instances for monitoring.

  • gh-119049: Fix displaying the source line for warnings created by the C API if the warnings module had not yet been imported.

  • gh-118844: Fix build failures when configuring with both --disable-gil and --enable-experimental-jit.

  • gh-118921: Add copy() method for FrameLocalsProxy which returns a snapshot dict for local variables.

  • gh-117657: Fix data races on the field that stores a pointer to the interpreter’s main thread that occur in free-threaded builds.

  • gh-118561: Fix race condition in free-threaded build where list.extend() could expose uninitialised memory to concurrent readers.

  • gh-117195: Avoid assertion failure for debug builds when calling object.__sizeof__(1)

Library

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

  • gh-117142: The ctypes module may now be imported in all subinterpreters, including those that have their own GIL.

  • gh-118835: Fix _pyrepl crash when using custom prompt with ANSI escape codes.

  • gh-117398: The _datetime module (C implementation for datetime) now supports being imported in multiple interpreters.

  • 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-119588: zipfile.Path.is_symlink now assesses if the given path is a symlink.

  • gh-119555: Catch SyntaxError from compile() in the runsource() method of the InteractiveColoredConsole. Patch by Sergey B Kirpichev.

  • 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-119443: The interactive REPL no longer runs with from __future__ import annotations enabled. Patch by Jelle Zijlstra.

  • gh-117398: Objects in the datetime C-API are now all statically allocated, which means better memory safety, especially when the module is reloaded. This should be transparent to users.

  • gh-118894: asyncio REPL now has the same capabilities as PyREPL.

  • gh-118911: In PyREPL, updated maybe-accept’s logic so that if the user hits Enter twice, they are able to terminate the block even if there’s trailing whitespace. Also, now when the user hits arrow up, the cursor is on the last functional line. This matches IPython’s behavior. Patch by Aya Elsayed.

  • gh-111201: Remove dependency to readline from the new Python REPL.

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

  • gh-119121: Fix a NameError happening in asyncio.staggered.staggered_race. This function is now tested.

  • gh-119113: Fix issue where pathlib.PurePath.with_suffix() didn’t raise TypeError when given None as a suffix.

  • 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-118895: Setting attributes on typing.NoDefault now raises AttributeError instead of TypeError.

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

  • gh-118851: ctx arguments to the constructors of ast node classes now default to ast.Load(). Patch by Jelle Zijlstra.

  • gh-118760: Restore the default value of tkiter.wantobjects to 1.

  • gh-118760: Fix errors in calling Tkinter bindings on Windows.

  • gh-118507: Fix os.path.isfile() on Windows for pipes. Speedup os.path.isjunction() and os.path.lexists() on Windows with a native implementation.

  • gh-118772: Allow typing.TypeVar instances without a default to follow instances without a default in some cases. Patch by Jelle Zijlstra.

  • gh-110863: os.path.realpath() now suppresses any OSError from os.readlink() when strict mode is disabled (the default).

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

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

  • gh-106531: In importlib.resources, sync with importlib_resources 6.3.2, including: MultiplexedPath now expects Traversable paths, deprecating string arguments to MultiplexedPath; Enabled support for resources in namespace packages in zip files; Fixed NotADirectoryError when calling files on a subdirectory of a namespace package.

  • gh-113978: Ignore warnings on text completion inside REPL.

  • 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).

  • 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.

Tests

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

Build

  • gh-119729: On POSIX systems, the pkg-config (.pc) filenames now include the ABI flags, which may include debug (“d”) and free-threaded (“t”). For example: * python-3.14.pc (default, non-debug build) * python-3.14d.pc (default, debug build) * python-3.14t.pc (free-threaded build)

  • gh-115119: Fall back to the bundled libmpdec if a system version cannot be found.

  • gh-119132: Update sys.version to identify whether the build is default build or free-threading build. Patch By Donghee Na.

  • gh-118836: Fix an AssertionError when building with --enable-experimental-jit and the compiler emits a SHT_NOTE section.

  • gh-118943: Fix a possible race condition affecting parallel builds configured with --enable-experimental-jit, in which compilation errors could be caused by an incompletely-generated header file.

Windows

  • gh-119679: Ensures correct import libraries are included in Windows installs.

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

  • gh-111201: Add support for new pyrepl on Windows

  • 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-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.

  • gh-118209: Avoid crashing in mmap on Windows when the mapped memory is inaccessible due to file system errors or access violations.

  • gh-116145: Updated bundled Tcl/Tk to 8.6.14.

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-119336: Restore the removed _PyLong_NumBits() function. It is used by the pywin32 project. Patch by Ethan Smith

  • gh-119247: Added Py_BEGIN_CRITICAL_SECTION_SEQUENCE_FAST and Py_END_CRITICAL_SECTION_SEQUENCE_FAST macros to make it possible to use PySequence_Fast APIs safely when free-threaded, and update str.join to work without the GIL using them.

  • gh-111389: Add PyHASH_MULTIPLIER constant: prime multiplier used in string and various other hashes. Patch by Victor Stinner.

  • gh-116984: Make mimalloc includes relative to the current file to avoid embedders or extensions needing to include Internal/mimalloc if they are already including internal CPython headers.

  • gh-118789: Restore _PyWeakref_ClearRef that was previously removed in Python 3.13 alpha 1.

Python 3.13.0 beta 1

Release date: 2024-05-08

Security

  • 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-118414: Add instrumented opcodes to YIELD_VALUE assertion for tracing cases.

  • gh-117953: When a builtin or extension module is imported for the first time, while a subinterpreter is active, the module’s init function is now run by the main interpreter first before import continues in the subinterpreter. Consequently, single-phase init modules now fail in an isolated subinterpreter without the init function running under that interpreter, whereas before it would run under the subinterpreter before failing, potentially leaving behind global state and callbacks and otherwise leaving the module in an inconsistent state.

  • gh-117549: Don’t use designated initializer syntax in inline functions in internal headers. They cause problems for C++ or MSVC users who aren’t yet using the latest C++ standard (C++20). While internal, pycore_backoff.h, is included (indirectly, via pycore_code.h) by some key 3rd party software that does so for speed.

  • gh-95382: Improve performance of json.dumps() and json.dump() when using the argument indent. Depending on the data the encoding using json.dumps() with indent can be up to 2 to 3 times faster.

  • gh-116322: In --disable-gil builds, the GIL will be enabled while loading C extension modules. If the module indicates that it supports running without the GIL, the GIL will be disabled once loading is complete. Otherwise, the GIL will remain enabled for the remainder of the interpreter’s lifetime. This behavior does not apply if the GIL has been explicitly enabled or disabled with PYTHON_GIL or -Xgil.

  • 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-118518: Allow the Linux perf support to work without frame pointers using perf’s advanced JIT support. The feature is activated when using the PYTHON_PERF_JIT_SUPPORT environment variable or when running Python with -Xperf_jit. Patch by Pablo Galindo.

  • gh-117514: Add sys._is_gil_enabled() function that returns whether the GIL is currently enabled. In the default build it always returns True because the GIL is always enabled. In the free-threaded build, it may return True or False.

  • 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-118473: Fix sys.set_asyncgen_hooks() not to be partially set when raising TypeError.

  • gh-118465: Compiler populates the new __firstlineno__ field on a class with the line number of the first line of the class definition.

  • gh-118492: Fix an issue where the type cache can expose a previously accessed attribute when a finalizer is run.

  • gh-117714: update async_generator.athrow().close() and async_generator.asend().close() to close their section of the underlying async generator

  • gh-111201: The interactive interpreter is now implemented in Python, which allows for a number of new features like colors, multiline input, history viewing, and paste mode. Contributed by Pablo Galindo, Łukasz Langa and Lysandros Nikolaou based on code from the PyPy project.

  • gh-74929: Implement PEP 667: converted FrameType.f_locals and PyFrame_GetLocals() to return a write-through proxy object when the frame refers to a function or comprehension.

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

  • gh-118335: Change how to use the tier 2 interpreter. Instead of running Python with -X uops or setting the environment variable PYTHON_UOPS=1, this choice is now made at build time by configuring with --enable-experimental-jit=interpreter.

    Beware! This changes the environment variable to enable or disable micro-ops to PYTHON_JIT. The old PYTHON_UOPS is no longer used.

  • gh-118306: Update JIT compilation to use LLVM 18

  • gh-118160: Annotation scopes within classes can now contain comprehensions. However, such comprehensions are not inlined into their parent scope at runtime. Patch by Jelle Zijlstra.

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

  • gh-118216: Don’t consider __future__ imports with dots before the module name.

  • gh-118074: Make sure that the Executor objects in the COLD_EXITS array aren’t assumed to be GC-able (which would access bytes outside the object).

  • gh-107674: Lazy load frame line number to improve performance of tracing

  • gh-118082: Improve SyntaxError message for imports without names, like in from x import and import cases. It now points out to users that import expects at least one name after it.

  • gh-118090: Improve SyntaxError message for empty type param brackets.

  • gh-117958: Added a get_jit_code() method to access JIT compiled machine code from the UOp Executor when the experimental JIT is enabled. Patch by Anthony Shaw.

  • gh-117901: Add option for compiler’s codegen to save nested instruction sequences for introspection.

  • gh-116622: Redirect stdout and stderr to system log when embedded in an Android app.

  • gh-109118: annotation scope within class scopes can now contain lambdas.

  • 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-117536: Fix a RuntimeWarning when calling agen.aclose().throw(Exception).

  • gh-117755: Fix mimalloc allocator for huge memory allocation (around 8,589,934,592 GiB) on s390x. Patch by Victor Stinner.

  • gh-117750: Fix issue where an object’s dict would get out of sync with the object’s internal values when being cleared. obj.__dict__.clear() now clears the internal values, but leaves the dict attached to the object.

  • gh-117431: Improve the performance of the following bytes and bytearray methods by adapting them to the METH_FASTCALL calling convention:

    • count()

    • find()

    • index()

    • rfind()

    • rindex()

  • gh-117709: Speed up calls to str() with positional-only argument, by using the PEP 590 vectorcall calling convention. Patch by Erlend Aasland.

  • gh-117680: Give _PyInstructionSequence a Python interface and use it in tests.

  • gh-115776: Statically allocated objects are, by definition, immortal so must be marked as such regardless of whether they are in extension modules or not.

  • gh-117385: Remove unhandled PY_MONITORING_EVENT_BRANCH and PY_MONITORING_EVENT_EXCEPTION_HANDLED events from sys.settrace().

  • gh-116322: Extension modules may indicate to the runtime that they can run without the GIL. Multi-phase init modules do so by calling providing Py_MOD_GIL_NOT_USED for the Py_mod_gil slot, while single-phase init modules call PyUnstable_Module_SetGIL(mod, Py_MOD_GIL_NOT_USED) from their init function.

  • gh-116129: Implement PEP 696, adding support for defaults on type parameters. Patch by Jelle Zijlstra.

  • gh-93502: Add two new functions to the C-API, PyRefTracer_SetTracer() and PyRefTracer_GetTracer(), that allows to track object creation and destruction the same way the tracemalloc module does. Patch by Pablo Galindo

  • gh-107674: Improved the performance of sys.settrace() significantly

  • gh-95754: Improve the error message when a script shadowing a module from the standard library causes AttributeError to be raised. Similarly, improve the error message when a script shadowing a third party module attempts to access an attribute from that third party module while still initialising.

  • gh-99180: Elide uninformative traceback indicators in return and simple assignment statements. Patch by Pablo Galindo.

  • gh-105879: Allow the globals and locals arguments to exec() and eval() to be passed as keywords.

Library

  • gh-118418: A DeprecationWarning is now emitted if you fail to pass a value to the new type_params parameter of typing._eval_type() or typing.ForwardRef._evaluate(). (Using either of these private and undocumented functions is discouraged to begin with, but failing to pass a value to the type_params parameter may lead to incorrect behaviour on Python 3.12 or newer.)

  • gh-118660: Add an optional second type parameter to typing.ContextManager and typing.AsyncContextManager, representing the return types of __exit__() and __aexit__() respectively. This parameter defaults to bool | None.

  • gh-118650: The enum module allows method named _repr_* to be defined on Enum types.

  • gh-118648: Add type parameter defaults to typing.Generator and typing.AsyncGenerator.

  • gh-101137: Mime type text/x-rst is now supported by mimetypes.

  • 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-111744: breakpoint() and pdb.set_trace() now enter the debugger immediately after the call rather than before the next line is executed.

  • gh-118500: Add pdb support for zipapps

  • gh-118406: Add signature for sqlite3.Connection objects.

  • gh-101732: Use a Y2038 compatible openssl time function when available.

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

  • gh-118402: Fix inspect.signature() for the result of the functools.cmp_to_key() call.

  • gh-116622: On Android, sysconfig.get_platform now returns the format specified by PEP 738.

  • gh-118285: Allow to specify the signature of custom callable instances of extension type by the __text_signature__ attribute. Specify signatures of operator.attrgetter, operator.itemgetter, and operator.methodcaller instances.

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

  • gh-118271: Add the PhotoImage methods read() to read an image from a file and data() to get the image data. Add background and grayscale parameters to PhotoImage method write().

  • gh-118225: Add the PhotoImage method copy_replace() to copy a region from one image to other image, possibly with pixel zooming and/or subsampling. Add from_coords parameter to PhotoImage methods copy(), zoom() and subsample(). Add zoom and subsample parameters to PhotoImage method copy().

  • gh-118221: Fix a bug where sqlite3.Connection.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-118218: Speed up itertools.pairwise() in the common case by up to 1.8x.

  • gh-117486: Improve the behavior of user-defined subclasses of ast.AST. Such classes will now require no changes in the usual case to conform with the behavior changes of the ast module in Python 3.13. Patch by Jelle Zijlstra.

  • 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-118131: Add command-line interface for the random module. Patch by Hugo van Kemenade.

  • gh-118107: Fix zipimport reading of ZIP64 files with file entries that are too big or offset too far.

  • gh-102511: Fix os.path.normpath() for UNC paths on Windows. Speed up os.path.splitroot() with a native implementation.

  • gh-117535: Change the unknown filename of warnings from sys to <sys> to clarify that it’s not a real filename.

  • 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-116931: Add parameter fileobj check for tarfile.TarFile.addfile()

  • 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-115874: Fixed a possible segfault during garbage collection of _asyncio.FutureIter objects. Patch by Savannah Ostrowski.

  • gh-115060: Speed up pathlib.Path.glob() by omitting an initial is_dir() call. As a result of this change, glob() can no longer raise OSError.

  • 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-76785: We’ve exposed the low-level _interpreters module for the sake of the PyPI implementation of PEP 734. It was sometimes available as the _xxsubinterpreters module and was formerly used only for testing. For the most part, it should be considered an internal module, like _thread and _imp. See https://discuss.python.org/t/pep-734-multiple-interpreters-in-the-stdlib/41147/26.

  • gh-115060: Speed up pathlib.Path.glob() by not scanning directories for non-wildcard pattern segments.

  • gh-117727: Speed up pathlib.Path.iterdir() by using os.scandir() internally.

  • gh-117586: Speed up pathlib.Path.walk() by working with strings internally.

  • gh-117722: Change the new multi-separator support in asyncio.StreamReader.readuntil() to only accept tuples of separators rather than arbitrary iterables.

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

  • gh-117348: Largely restored import time performance of configparser by avoiding dataclasses.

  • gh-117641: Speedup os.path.commonpath() on Unix.

  • gh-117663: Fix _simple_enum to detect aliases when multiple arguments are present but only one is the member value.

  • gh-117636: Speedup os.path.join().

  • gh-117618: Support package.module as filename for break command of pdb

  • gh-102247: the status codes enum with constants in http.HTTPStatus are updated to include the names from RFC9110. This RFC includes some HTTP statuses previously only used for WEBDAV and assigns more generic names to them.

    The old constants are preserved for backwards compatibility.

  • gh-117607: Speedup os.path.relpath().

  • gh-117586: Speed up pathlib.Path.glob() by working with strings internally.

  • gh-117225: Add colour to doctest output. Patch by Hugo van Kemenade.

  • 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-117546: Fix issue where os.path.realpath() stopped resolving symlinks after encountering a symlink loop on POSIX.

  • gh-116720: Improved behavior of asyncio.TaskGroup when an external cancellation collides with an internal cancellation. For example, when two task groups are nested and both experience an exception in a child task simultaneously, it was possible that the outer task group would misbehave, because its internal cancellation was swallowed by the inner task group.

    In the case where a task group is cancelled externally and also must raise an ExceptionGroup, it will now call the parent task’s cancel() method. This ensures that a asyncio.CancelledError will be raised at the next await, so the cancellation is not lost.

    An added benefit of these changes is that task groups now preserve the cancellation count (asyncio.Task.cancelling()).

    In order to handle some corner cases, asyncio.Task.uncancel() may now reset the undocumented _must_cancel flag when the cancellation count reaches zero.

  • gh-117516: Add typing.TypeIs, implementing PEP 742. Patch by Jelle Zijlstra.

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

  • gh-117394: os.path.ismount() is now 2-3 times faster if the user has permissions.

  • 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-117142: Convert _ctypes to multi-phase initialisation (PEP 489).

  • gh-66543: Add the mimetypes.guess_file_type() function which works with file path. Passing file path instead of URL in guess_type() is soft deprecated.

  • gh-68583: webbrowser CLI: replace getopt with argparse, add long options. Patch by Hugo van Kemenade.

  • gh-116871: Name suggestions for AttributeError and ImportError now only include underscored names if the original name was underscored.

  • gh-116023: Don’t show empty fields (value None or []) in ast.dump() by default. Add show_empty=False parameter to optionally show them.

  • gh-115961: Added name and mode attributes for compressed and archived file-like objects in modules bz2, lzma, tarfile and zipfile. The value of the mode attribute of gzip.GzipFile was changed from integer (1 or 2) to string ('rb' or 'wb'). The value of the mode attribute of the readable file-like object returned by zipfile.ZipFile.open() was changed from 'r' to 'rb'.

  • gh-82062: Fix inspect.signature() to correctly handle parameter defaults on methods in extension modules that use names defined in the module namespace.

  • gh-83856: Honor atexit for all multiprocessing start methods

  • gh-113081: Print colorized exception just like built-in traceback in pdb

  • gh-112855: Speed up pickling of pathlib.PurePath objects. Patch by Barney Gale.

  • gh-111744: Support opcode events in bdb

  • gh-109617: ncurses: fixed a crash that could occur on macOS 13 or earlier when Python was built with Apple Xcode 15’s SDK.

  • gh-83151: Enabled arbitrary statements and evaluations in pdb shell to access the local variables of the current frame, which made it possible for multi-scope code like generators or nested function to work.

  • gh-110209: Add __class_getitem__() to types.GeneratorType and types.CoroutineType for type hinting purposes. Patch by James Hilton-Balfe.

  • gh-108191: The types.SimpleNamespace now accepts an optional positional argument which specifies initial values of attributes as a dict or an iterable of key-value pairs.

  • gh-62090: Fix assertion errors caused by whitespace in metavars or SUPPRESS-ed groups in argparse by simplifying usage formatting. Patch by Ali Hamdan.

  • gh-102402: Adjust logging.LogRecord to use time.time_ns() and fix minor bug related to floating-point math.

  • gh-100242: Bring pure Python implementation functools.partial.__new__ more in line with the C-implementation by not just always checking for the presence of the attribute 'func' on the first argument of partial. Instead, both the Python version and the C version perform an isinstance(func, partial) check on the first argument of partial.

  • gh-99730: HEAD requests are no longer upgraded to GET request during redirects in urllib.

  • gh-66410: Setting the tkinter module global wantobjects to 2 before creating the Tk object or call the wantobjects() method of the Tk object with argument 2 makes now arguments to callbacks registered in the tkinter module to be passed as various Python objects (int, float, bytes, tuple), depending on their internal representation in Tcl, instead of always str. tkinter.wantobjects is now set to 2 by default.

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

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

  • bpo-18108: shutil.chown() now supports dir_fd and follow_symlinks keyword arguments.

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

  • bpo-32839: Add the after_info() method for Tkinter widgets.

Documentation

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

Build

  • gh-118734: Fixes Windows build when invoked directly (not through the build.bat script) without specifying a value for UseTIER2.

  • gh-115119: The configure option --with-system-libmpdec now defaults to yes. The bundled copy of libmpdecimal will be removed in Python 3.15.

  • gh-117845: Fix building against recent libedit versions by detecting readline hook signatures in configure.

  • gh-116622: A testbed project was added to run the test suite on Android.

  • gh-117645: Increase WASI stack size from 512 KiB to 8 MiB and the initial memory from 10 MiB to 20 MiB. Patch by Victor Stinner.

  • gh-115119: configure now uses pkg-config to detect decimal dependencies if the --with-system-libmpdec option is given.

Windows

  • gh-115119: Update Windows installer to use libmpdecimal 4.0.0.

  • gh-118486: os.mkdir() now accepts mode of 0o700 to restrict the new directory to the current user.

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

  • gh-118293: The multiprocessing module now passes the STARTF_FORCEOFFFEEDBACK flag when spawning processes to tell Windows not to change the mouse cursor.

  • 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.

  • gh-117786: Fixes virtual environments not correctly launching when created from a Store install.

macOS

  • gh-115119: Update macOS installer to use libmpdecimal 4.0.0.

  • gh-114099: iOS preprocessor symbol usage was made compatible with older macOS SDKs.

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

  • gh-91629: Use ~/.config/fish/conf.d configs and fish_add_path to set PATH when installing for the Fish shell.

IDLE

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

C API

Python 3.13.0 alpha 6

Release date: 2024-04-09

Core and Builtins

  • gh-117494: Refactored the instruction sequence data structure out of compile.c into instruction_sequence.c.

  • gh-116968: Introduce a unified 16-bit backoff counter type (_Py_BackoffCounter), shared between the Tier 1 adaptive specializer and the Tier 2 optimizer. The API used for adaptive specialization counters is changed but the behavior is (supposed to be) identical.

    The behavior of the Tier 2 counters is changed:

    • There are no longer dynamic thresholds (we never varied these).

    • All counters now use the same exponential backoff.

    • The counter for JUMP_BACKWARD starts counting down from 16.

    • The temperature in side exits starts counting down from 64.

  • gh-117431: Improve the performance of the following bytes and bytearray methods by adapting them to the METH_FASTCALL calling convention:

    • endswith()

    • startswith()

  • gh-117431: Improve the performance of the following str methods by adapting them to the METH_FASTCALL calling convention:

  • gh-117411: Move PyFutureFeatures to an internal header and make it private.

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

  • gh-117266: Fix crashes for certain user-created subclasses of ast.AST. Such classes are now expected to set the _field_types attribute.

  • 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-117108: Change the old space bit of objects in the young generation from 0 to gcstate->visited, so that any objects created during GC will have the old bit set correctly if they get moved into the old generation.

  • gh-117108: The cycle GC now chooses the size of increments based on the total heap size, instead of the rate of object creation. This ensures that it can keep up with growing heaps.

  • 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-116626: Ensure INSTRUMENTED_CALL_FUNCTION_EX always emits CALL

  • gh-116554: list.sort() now exploits more cases of partial ordering, particularly those with long descending runs with sub-runs of equal values. Those are recognized as single runs now (previously, each block of repeated values caused a new run to be created).

  • gh-114099: Added a Loader that can discover extension modules in an iOS-style Frameworks folder.

  • gh-115775: Compiler populates the new __static_attributes__ field on a class with the names of attributes of this class which are accessed through self.X from any function in its body.

  • gh-115776: The array of values, the PyDictValues struct is now embedded in the object during allocation. This provides better performance in the common case, and does not degrade as much when the object’s __dict__ is materialized.

  • gh-108362: Implement an incremental cyclic garbage collector. By collecting the old generation in increments, there is no need for a full heap scan. This can hugely reduce maximum pause time for programs with large heaps.

    Reduce the number of generations from three to two. The old generation is split into two spaces, “visited” and “pending”.

    Collection happens in two steps:: * An increment is formed from the young generation and a small part of the pending space. * This increment is scanned and the survivors moved to the end of the visited space.

    When the collecting space becomes empty, the two spaces are swapped.

  • gh-109870: Dataclasses now calls exec() once per dataclass, instead of once per method being added. This can speed up dataclass creation by up to 20%.

  • gh-97901: Mime type text/rtf is now supported by mimetypes.

  • bpo-24612: Improve the SyntaxError that happens when ‘not’ appears after an operator. Patch by Pablo Galindo

Library

  • gh-117648: Improve performance of os.path.join() and os.path.expanduser().

  • gh-117584: Raise TypeError for non-paths in posixpath.relpath().

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

  • gh-114848: Raise FileNotFoundError when getcwd() returns ‘(unreachable)’, which can happen on Linux >= 2.6.36 with glibc < 2.27.

  • gh-117459: asyncio.asyncio.run_coroutine_threadsafe() now keeps the traceback of CancelledError, TimeoutError and InvalidStateError which are raised in the coroutine.

  • gh-117381: Fix error message for ntpath.commonpath().

  • gh-117337: Deprecate undocumented glob.glob0() and glob.glob1() functions. Use glob.glob() and pass a directory to its root_dir argument instead.

  • gh-117349: Optimise several functions in os.path.

  • gh-117348: Refactored configparser.RawConfigParser._read() to reduce cyclometric complexity and improve comprehensibility.

  • gh-117335: Raise TypeError for non-sequences for ntpath.commonpath().

  • gh-66449: configparser.ConfigParser now accepts unnamed sections before named ones, if configured to do so.

  • gh-88014: In documentation of gzip.GzipFile in module gzip, explain data type of optional constructor argument mtime, and recommend mtime = 0 for generating deterministic streams.

  • 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-117294: A DocTestCase now reports as skipped if all examples in the doctest are skipped.

  • gh-98966: In subprocess, raise a more informative message when stdout=STDOUT.

  • gh-117225: doctest: only print “and X failed” when non-zero, don’t pluralise “1 items”. Patch by Hugo van Kemenade.

  • gh-117205: Speed up compileall.compile_dir() by 20% when using multiprocessing by increasing chunksize.

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

  • gh-112383: Fix dis module’s handling of ENTER_EXECUTOR instructions.

  • gh-117182: Lazy-loading of modules that modify their own __class__ no longer reverts the __class__ to types.ModuleType.

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

  • gh-117114: Make os.path.isdevdrive() available on all platforms. For those that do not offer Dev Drives, it will always return False.

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

  • gh-109653: Deferred select imports in importlib.metadata and importlib.resources for a 14% speedup.

  • gh-70647: Start the deprecation period for the current behavior of datetime.datetime.strptime() and time.strptime() which always fails to parse a date string with a ValueError involving a day of month such as strptime("02-29", "%m-%d") when a year is not specified and the date happen to be February 29th. This should help avoid users finding new bugs every four years due to a natural mistaken assumption about the API when parsing partial date values.

  • gh-116987: Fixed inspect.findsource() for class code objects.

  • gh-114099: Modify standard library to allow for iOS platform differences.

  • 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-115538: _io.WindowsConsoleIO now emit a warning if a boolean value is passed as a filedescriptor argument.

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

  • gh-106531: Refreshed zipfile._path from zipp 3.18, providing better compatibility for PyPy, better glob performance for deeply nested zipfiles, and providing internal access to CompleteDirs.inject for use in other tests (like importlib.resources).

  • gh-63207: On Windows, time.time() now uses the GetSystemTimePreciseAsFileTime() clock to have a resolution better than 1 us, instead of the GetSystemTimeAsFileTime() clock which has a resolution of 15.6 ms. Patch by Victor Stinner.

  • 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-116647: Fix recursive child in dataclasses

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

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

  • gh-63283: In encodings.idna, any capitalization of the ACE prefix (xn--) is now acceptable. Patch by Pepijn de Vos and Zackery Spytz.

  • gh-71042: Add platform.android_ver(), which provides device and OS information on Android.

  • gh-73468: Added new math.fma() function, wrapping C99’s fma() operation: fused multiply-add function. Patch by Mark Dickinson and Victor Stinner.

  • gh-116608: The importlib.resources functions is_resource(), open_binary(), open_text(), path(), read_binary(), and read_text() are un-deprecated, and support subdirectories via multiple positional arguments. The contents() function also allows subdirectories, but remains deprecated.

  • 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-114314: In ctypes, ctype data is now stored in type objects directly rather than in a dict subclass. This is an internal change that should not affect usage.

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

  • gh-71052: Implement ctypes.util.find_library() on Android.

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

  • gh-113308: Remove some internal protected parts from uuid: _has_uuid_generate_time_safe, _netbios_getnode, _ipconfig_getnode, and _load_system_functions. They were unused.

  • gh-115627: Fix the ssl module error handling of connection terminate by peer. It now throws an OSError with the appropriate error code instead of an EOFError.

  • gh-114847: Speed up os.path.realpath() on non-Windows platforms.

  • gh-114271: Fix a race in threading.Thread.join().

    threading._MainThread now always represents the main thread of the main interpreter.

    PyThreadState.on_delete and PyThreadState.on_delete_data have been removed.

  • gh-113538: Add asyncio.Server.close_clients() and asyncio.Server.abort_clients() methods which allow to more forcefully close an asyncio server.

  • gh-85287: Changes Unicode codecs to return UnicodeEncodeError or UnicodeDecodeError, rather than just UnicodeError.

  • gh-113548: pdb now allows CLI arguments to pdb -m.

  • gh-112948: Make completion of pdb similar to Python REPL

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

  • gh-96471: Add asyncio.Queue termination with shutdown() method.

  • gh-89739: The zipimport module can now read ZIP64 files.

  • bpo-33533: asyncio.as_completed() now returns an object that is both an asynchronous iterator and plain iterator. The new asynchronous iteration pattern allows for easier correlation between prior tasks and their completed results. This is a closer match to concurrent.futures.as_completed()’s iteration pattern. Patch by Justin Arthur.

  • bpo-27578: inspect.getsource() (and related functions) work with empty module files, returning '\n' (or reasonable equivalent) instead of raising OSError. Patch by Kernc.

  • bpo-37141: Accept an iterable of separators in asyncio.StreamReader.readuntil(), stopping when one of them is encountered.

  • 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-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-115977: Remove compatibility references to Emscripten.

  • gh-114099: Add an iOS platform guide, and flag modules not available on iOS.

  • 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-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-117089: Consolidated tests for importlib.metadata in their own metadata package.

  • 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.

Build

  • gh-114736: Have WASI builds use WASI SDK 21.

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

  • gh-71052: Add Android build script and instructions.

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-116195: Improves performance of os.getppid() by using an alternate system API when available. Contributed by vxiiduu.

  • gh-88494: On Windows, time.monotonic() now uses the QueryPerformanceCounter() clock to have a resolution better than 1 us, instead of the GetTickCount64() clock which has a resolution of 15.6 ms. Patch by Victor Stinner.

  • 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-115119: Switched from vendored libmpdecimal code to a separately-hosted external package in the cpython-source-deps repository when building the _decimal module.

C API

  • gh-117642: Fix PEP 737 implementation for %#T and %#N.

  • gh-87193: _PyBytes_Resize() can now be called for bytes objects with reference count > 1, including 1-byte bytes objects. It creates a new bytes object and destroys the old one if it has reference count > 1.

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

  • gh-115756: PyCode_GetFirstFree() is an ustable API now and has been renamed to PyUnstable_Code_GetFirstFree(). (Contributed by Bogdan Romanyuk in gh-115781)

  • gh-116869: Add test_cext test: build a C extension to check if the Python C API emits C compiler warnings. Patch by Victor Stinner.

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

  • gh-116936: Add PyType_GetModuleByDef() to the limited C API. Patch by Victor Stinner.

  • gh-116809: Restore removed private _PyErr_ChainExceptions1() function. Patch by Victor Stinner.

  • gh-115754: In the limited C API version 3.13, getting Py_None, Py_False, Py_True, Py_Ellipsis and Py_NotImplemented singletons is now implemented as function calls at the stable ABI level to hide implementation details. Getting these constants still return borrowed references. Patch by Victor Stinner.

  • gh-115754: Add Py_GetConstant() and Py_GetConstantBorrowed() functions to get constants. For example, Py_GetConstant(Py_CONSTANT_ZERO) returns a strong reference to the constant zero. Patch by Victor Stinner.

  • gh-111696: Add support for %T, %T#, %N and %N# formats to PyUnicode_FromFormat(): format the fully qualified name of an object type and of a type: call PyType_GetModuleName(). See PEP 737 for more information. Patch by Victor Stinner.

  • gh-111696: Add PyType_GetModuleName() function to get the type’s module name. Equivalent to getting the type.__module__ attribute. Patch by Eric Snow and Victor Stinner.

  • gh-111696: Add PyType_GetFullyQualifiedName() function to get the type’s fully qualified name. Equivalent to f"{type.__module__}.{type.__qualname__}", or type.__qualname__ if type.__module__ is not a string or is equal to "builtins". Patch by Victor Stinner.

  • gh-85283: The fcntl, grp, pwd, termios, _statistics and _testconsole C extensions are now built with the limited C API. Patch by Victor Stinner.

  • gh-111140: Add additional flags to PyLong_AsNativeBytes() and PyLong_FromNativeBytes() to allow the caller to determine how to handle edge cases around values that fill the entire buffer.

  • gh-113024: Add PyObject_GenericHash() function.

Python 3.13.0 alpha 5

Release date: 2024-03-12

Security

Core and Builtins

  • 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-112087: list is now compatible with the implementation of PEP 703.

  • gh-116381: Add specialization for CONTAINS_OP.

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

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

  • gh-115778: Add tierN annotation for instruction definition in interpreter DSL.

  • gh-115733: Fix crash when calling next() on exhausted list iterators.

  • gh-115700: The regen-cases build stage now works on Windows.

  • gh-115347: Fix bug where docstring was replaced by a redundant NOP when Python is run with -OO.

  • gh-115323: Make error message more meaningful for when bytearray.extend() is called with a str object.

  • gh-112175: Every PyThreadState now has its own eval_breaker, allowing specific threads to be interrupted.

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

  • gh-112433: Add ability to force alignment of ctypes.Structure by way of the new _align_ attribute on the class.

  • gh-104090: The multiprocessing resource tracker now exits with non-zero status code if a resource leak was detected. It still exits with status code 0 otherwise.

  • gh-105858: Improve the constructors for ast nodes. Arguments of list types now default to an empty list if omitted, and optional fields default to None. AST nodes now have an __annotations__ attribute with the expected types of their attributes. Passing unrecognized extra arguments to AST nodes is deprecated and will become an error in Python 3.15. Omitting a required argument to an AST node is deprecated and will become an error in Python 3.15. Patch by Jelle Zijlstra.

  • gh-101860: Expose __name__ attribute on property.

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

Library

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

  • gh-116349: platform.java_ver() is deprecated and will be removed in 3.15. It was largely untested, had a confusing API, and was only useful for Jython support.

  • 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-116127: typing: implement PEP 705 which adds typing.ReadOnly support to typing.TypedDict.

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

  • gh-115957: When asyncio.TaskGroup.create_task is called on an inactive asyncio.TaskGroup, the given coroutine will be closed (which prevents a RuntimeWarning).

  • 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-89547: Add support for nested typing special forms like Final[ClassVar[int]].

  • gh-65824: Improve the less prompt in pydoc.

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

  • gh-115821: [Enum] Improve error message when calling super().__new__() in custom __new__.

  • gh-85644: Use the XDG_CURRENT_DESKTOP environment variable in webbrowser to check desktop. Prefer it to the deprecated GNOME_DESKTOP_SESSION_ID for GNOME detection.

  • 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-115532: Add kernel density estimation to the statistics module.

  • gh-115714: On WASI, the time module no longer get process time using times() or CLOCK_PROCESS_CPUTIME_ID, system API is that is unreliable and is likely to be removed from WASI. The affected clock functions fall back to calling clock().

  • 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: Restore support of space delimiter with skipinitialspace=True in csv. 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-112997: Stop logging potentially sensitive callback arguments in asyncio unless debug mode is active.

  • gh-114914: Fix an issue where an abandoned StreamWriter would not be garbage collected.

  • 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-112720: Refactor dis.ArgResolver to make it possible to subclass and change the way jump args are interpreted.

  • gh-112006: Fix inspect.unwrap() for types with the __wrapper__ data descriptor. Fix inspect.Signature.from_callable() for builtins classmethod() and staticmethod().

  • 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-103092: Isolate _lsprof (apply PEP 687).

  • gh-113942: pydoc no longer skips global functions implemented as builtin methods, such as MethodDescriptorType and WrapperDescriptorType.

  • gh-115256: Added DeprecationWarning when accessing the tarfile attribute of TarInfo objects. The attribute is never used internally and is only attached to TarInfos when the tarfile is opened in write-mode, not read-mode. The attribute creates an unnecessary reference cycle which may cause corruption when not closing the handle after writing a tarfile.

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

  • gh-113812: DatagramTransport.sendto() will now send zero-length datagrams if called with an empty bytes object. The transport flow control also now accounts for the datagram header when calculating the buffer size.

  • 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-114709: posixpath.commonpath() now raises a ValueError exception when passed an empty iterable. Previously, IndexError was raised.

    posixpath.commonpath() now raises a TypeError exception when passed None. Previously, ValueError was raised.

  • gh-114610: Fix bug where pathlib.PurePath.with_stem() converted a non-empty path suffix to a stem when given an empty stem argument. It now raises ValueError, just like pathlib.PurePath.with_suffix() does when called on a path with an empty stem, given a non-empty suffix argument.

  • gh-107361: Add ssl.VERIFY_X509_PARTIAL_CHAIN and VERIFY_X509_STRICT to the default SSL context created with ssl.create_default_context().

  • 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-107625: Raise configparser.ParsingError from read() and read_file() methods of configparser.ConfigParser if a key without a corresponding value is continued (that is, followed by an indented line).

  • 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-57141: Add option for non-shallow comparisons to filecmp.dircmp like filecmp.cmp(). Original patch by Steven Ward. Enhanced by Tobias Rautenkranz

  • gh-69990: Profile.print_stats() has been improved to accept multiple sort arguments. Patched by Chiu-Hsiang Hsu and Furkan Onder.

  • gh-104061: Add socket.SO_BINDTOIFINDEX constant.

  • gh-60346: Fix ArgumentParser inconsistent with parse_known_args.

  • gh-102389: Add windows_31j to aliases for cp932 codec

  • gh-72249: functools.partial`s of :func:`repr() has been improved to include the module name. Patched by Furkan Onder and Anilyka Barry.

  • 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-31116: Add Z85 encoding to base64.

  • 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.

  • bpo-41122: Failing to pass arguments properly to functools.singledispatchmethod() now throws a TypeError instead of hitting an index out of bounds internally.

  • bpo-40818: The asyncio REPL now runs sys.__interactivehook__ on startup. The default implementation of sys.__interactivehook__ provides auto-completion to the asyncio REPL. Patch contributed by Rémi Lapeyre.

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

Documentation

Tests

  • gh-71052: Add test exclusions to support running the test suite on Android.

  • gh-71052: Enable test_concurrent_futures on platforms that support threading but not multiprocessing.

  • gh-115796: Make ‘_testinternalcapi.assemble_code_object’ construct the exception table for the code object.

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

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

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

  • gh-115556: On Windows, commas passed in arguments to Tools\buildbot\test.bat and PCbuild\\rt.bat are now properly handled.

  • gh-115420: Fix translation of exception handler targets by _testinternalcapi.optimize_cfg.

  • gh-115376: Fix segfault in _testinternalcapi.compiler_codegen on bad input.

Build

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

  • gh-71052: Change Android’s sys.platform from "linux" to "android".

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

  • gh-71052: Fix several Android build issues

  • gh-114099: A testbed project was added to run the test suite on iOS.

  • gh-115350: Fix building ctypes module with -DWIN32_LEAN_AND_MEAN defined

  • gh-111225: Link extension modules against libpython on Android.

  • gh-115737: The install name for libPython is now correctly set for non-framework macOS builds.

  • gh-114099: Makefile targets were added to support compiling an iOS-compatible framework build.

Windows

  • gh-116012: Ensure the value of GetLastError() is preserved across GIL operations.

  • gh-115582: Building extensions intended for free-threaded builds of CPython now require compiling with /DPy_GIL_DISABLED manually when using a regular install. This is expected to change in future releases.

  • 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.

macOS

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

IDLE

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

Tools/Demos

  • gh-100176: Remove outdated Tools/{io,cc,string}bench

  • bpo-45101: Add consistency in usage message IO between 2 versions of python-config.

C API

  • gh-114626: Add again _PyCFunctionFastWithKeywords name, removed in Python 3.13 alpha 4 by mistake. Keep the old private _PyCFunctionFastWithKeywords name (Python 3.7) as an alias to the new public name PyCFunctionFastWithKeywords (Python 3.13a4). Patch by Victor Stinner.

  • gh-111418: Add PyHASH_MODULUS, PyHASH_BITS, PyHASH_INF and PyHASH_IMAG C macros. Patch by Sergey B Kirpichev.

Python 3.13.0 alpha 4

Release date: 2024-02-15

Security

Core and Builtins

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

  • gh-114570: Add PythonFinalizationError exception. This exception derived from RuntimeError is raised when an operation is blocked during the Python finalization. Patch by Victor Stinner.

  • gh-114695: Add sys._clear_internal_caches(), which clears all internal performance-related caches (and deprecate the less-general sys._clear_type_cache() function).

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

  • gh-112069: Adapt set and frozenset methods to Argument Clinic.

  • 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-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-114944: Fixes a race between PyParkingLot_Park and _PyParkingLot_UnparkAll.

  • gh-113462: Limit the number of versions that a single class can use. Prevents a few wayward classes using up all the version numbers.

  • gh-76763: The chr() builtin function now always raises ValueError for values outside the valid range. Previously it raised OverflowError for very large or small values.

  • gh-114806: No longer specialize calls to classes, if those classes have metaclasses. Fixes bug where the __call__ method of the metaclass was not being called.

  • gh-107944: Improve error message for function calls with bad keyword arguments via getargs

  • gh-112529: The free-threaded build no longer allocates space for the PyGC_Head structure in objects that support cyclic garbage collection. A number of other fields and data structures are used as replacements, including ob_gc_bits, ob_tid, and mimalloc internal data structures.

  • gh-114456: Lower the recursion limit under a debug build of WASI.

  • gh-114083: Compiler applies folding of LOAD_CONST with following instruction in a separate pass before other optimisations. This enables jump threading in certain circumstances.

  • 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-114265: Compiler propagates line numbers before optimization, leading to more optimization opportunities and removing the need for the guarantee_lineno_for_exits hack.

  • gh-112529: The free-threaded build now has its own thread-safe GC implementation that uses mimalloc to find GC tracked objects. It is non-generational, unlike the existing GC implementation.

  • gh-114050: Fix segmentation fault caused by an incorrect format string in TypeError exception when more than two arguments are passed to int.

  • gh-112354: The END_FOR instruction now pops only one value. This is to better support side exits in loops.

  • gh-113884: Make queue.SimpleQueue thread safe when the GIL is disabled.

  • gh-114058: Implement the foundations of the Tier 2 redundancy eliminator.

  • gh-113939: frame.clear(): Clear frame.f_locals as well, and not only the fast locals. This is relevant once frame.f_locals was accessed, which would contain also references to all the locals.

  • gh-112050: Convert collections.deque to use Argument Clinic.

  • gh-112050: Make methods on collections.deque thread-safe when the GIL is disabled.

  • gh-113464: Add an option (--enable-experimental-jit for configure-based builds or --experimental-jit for PCbuild-based ones) to build an experimental just-in-time compiler, based on copy-and-patch

  • gh-113055: Make interp->obmalloc a pointer. For interpreters that share state with the main interpreter, this points to the same static memory structure. For interpreters with their own obmalloc state, it is heap allocated. Add free_obmalloc_arenas() which will free the obmalloc arenas and radix tree structures for interpreters with their own obmalloc state.

  • gh-55664: Add warning when creating type using a namespace dictionary with non-string keys. Patched by Daniel Urban and Furkan Onder.

  • gh-104530: Use native Win32 condition variables.

Library

  • 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-102840: Fix confused traceback when floordiv, mod, or divmod operations happens between instances of fractions.Fraction and complex.

  • 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-112903: Fix “issubclass() arg 1 must be a class” errors in certain cases of multiple inheritance with generic aliases (regression in early 3.13 alpha releases).

  • 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-67837: Avoid race conditions in the creation of directories during concurrent extraction in tarfile and zipfile.

  • gh-115060: Speed up pathlib.Path.glob() by removing redundant regex matching.

  • gh-97928: Partially revert the behavior of tkinter.Text.count(). By default it preserves the behavior of older Python versions, except that setting wantobjects to 0 no longer has effect. Add a new parameter return_ints: specifying return_ints=True makes Text.count() always returning the single count as an integer instead of a 1-tuple or None.

  • gh-114628: When csv.Error is raised when handling TypeError, do not print the TypeError traceback.

  • gh-85984: Added _POSIX_VDISABLE from C’s <unistd.h> to termios.

  • 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-114894: Add array.array.clear().

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

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

  • gh-49766: Fix date-datetime comparison. Now the special comparison methods like __eq__ and __lt__ return NotImplemented if one of comparands is date and other is datetime instead of ignoring the time part and the time zone or forcefully return “not equal” or raise TypeError. It makes comparison of date and datetime subclasses more symmetric and allows to change the default behavior by overriding the special comparison methods in subclasses.

  • 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-114678: Ensure that deprecation warning for ‘N’ specifier in Decimal format is not raised for cases where ‘N’ appears in other places in the format specifier. Based on patch by Stefan Krah.

  • gh-70303: Return both files and directories from pathlib.Path.glob() if a pattern ends with “**”. Previously only directories were returned.

  • gh-109653: Improve import time of importlib.metadata and email.utils.

  • 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-83383: Synchronization of the dbm.dumb database is now no-op if there was no modification since opening or last synchronization. The directory file for a newly created empty dbm.dumb database is now created immediately after opening instead of deferring this until synchronizing or closing.

  • gh-91602: Add filter keyword-only parameter to sqlite3.Connection.iterdump() for filtering database objects to dump. Patch by Mariusz Felisiak.

  • gh-112451: Prohibit subclassing pure-Python datetime.timezone. This is consistent with C-extension implementation. Patch by Mariusz Felisiak.

  • gh-69893: Add the close() method for the iterator returned by xml.etree.ElementTree.iterparse().

  • gh-109653: Reduce the import time of threading module by ~50%. Patch by Daniel Hollas.

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

  • gh-114315: Make threading.Lock a real class, not a factory function. Add __new__ to _thread.lock type.

  • gh-100414: Add dbm.sqlite3 as a backend to dbm, and make it the new default dbm backend. Patch by Raymond Hettinger and Erlend E. Aasland.

  • 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-114423: _DummyThread entries in threading._active are now automatically removed when the related thread dies.

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

  • gh-114321: Expose more platform specific constants in the fcntl module on Linux, macOS, FreeBSD and NetBSD.

  • 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-114281: Remove type hints from Lib/asyncio/staggered.py. The annotations in the typeshed project should be used instead.

  • 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-114198: The signature for the __replace__ method on dataclasses now has the first argument named self, rather than obj.

  • 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-83648: Support deprecation of options, positional arguments and subcommands in argparse.

  • gh-114087: Speed up dataclasses.asdict up to 1.35x.

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

  • gh-79634: Accept path-like objects as patterns in pathlib.Path.glob() and rglob().

  • gh-112202: Ensure that a asyncio.Condition.notify() call does not get lost if the awakened Task is simultaneously cancelled or encounters any other error.

  • 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-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-113796: Add more validation checks in the csv.Dialect constructor. ValueError is now raised if the same character is used in different roles.

  • gh-113732: Fix support of QUOTE_NOTNULL and QUOTE_STRINGS in csv.reader().

  • gh-113225: Speed up pathlib.Path.walk() by using os.DirEntry.path where possible.

  • gh-89039: When replace() method is called on a subclass of datetime, date or time, properly call derived constructor. Previously, only the base class’s constructor was called.

    Also, make sure to pass non-zero fold values when creating subclasses in various methods. Previously, fold was silently ignored.

  • gh-112919: Speed-up datetime.datetime.replace(), datetime.date.replace() and datetime.time.replace().

  • gh-59013: Set breakpoint on the first executable line of the function, instead of the line of function definition when the user do break func using pdb

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

  • gh-112240: Add option to calendar module CLI to specify the weekday to start each week. Patch by Steven Ward.

  • gh-111741: Recognise image/webp as a standard format in the mimetypes module.

  • gh-43457: Fix the tkinter widget method wm_attributes(). It now accepts the attribute name without the minus prefix to get window attributes and allows to specify attributes and values to set as keyword arguments. Add new optional keyword argument return_python_dict: calling w.wm_attributes(return_python_dict=True) returns the attributes as a dict instead of a tuple. Calling w.wm_attributes() now returns a tuple instead of string if wantobjects was set to 0.

  • gh-82626: Many functions now emit a warning if a boolean value is passed as a file descriptor argument.

  • gh-111051: Added check for file modification during debugging with pdb

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

  • 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-96471: Add queue.Queue termination with shutdown().

  • gh-101599: Changed argparse flag options formatting to remove redundancy.

  • gh-85984: Add POSIX pseudo-terminal functions os.posix_openpt(), os.grantpt(), os.unlockpt(), and os.ptsname().

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

  • gh-88569: Add os.path.isreserved(), which identifies reserved pathnames such as “NUL”, “AUX” and “CON”. This function is only available on Windows.

    Deprecate pathlib.PurePath.is_reserved().

  • bpo-38364: The inspect functions isgeneratorfunction, iscoroutinefunction, isasyncgenfunction now support functools.partialmethod wrapped functions the same way they support functools.partial.

Documentation

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

  • gh-114123: Move the csv module docstring to the csv module instead of reexporting it from the internal _csv module, and remove __doc__ from csv.__all__.

    Move csv.__version__ to the csv module instead of reexporting it from the internal _csv module, and remove __version__ from csv.__all__.

Tests

  • gh-114099: Added test exclusions required to run the test suite on iOS.

  • 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

Build

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

  • gh-113632: Promote WASI to a tier 2 platform and drop Emscripten from tier 3 in configure.ac.

  • gh-114099: configure and Makefile were refactored to accommodate framework builds on Apple platforms other than macOS.

  • gh-114875: Add getgrent() as a prerequisite for building the grp module.

Windows

  • 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.

  • 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-112984: Adds free-threaded binaries to Windows installer as an optional component.

  • gh-89240: Allows multiprocessing to create pools of greater than 62 processes.

macOS

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

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

  • gh-114490: Add Mach-O linkage support for platform.architecture().

  • gh-87804: On macOS the result of os.statvfs and os.fstatvfs now correctly report the size of very large disks, in previous versions the reported number of blocks was wrong for disks with at least 2**32 blocks.

IDLE

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

  • 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.

Tools/Demos

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

  • 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.

C API

Python 3.13.0 alpha 3

Release date: 2024-01-17

Security

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

  • gh-112302: Created a Software Bill-of-Materials document and tooling for tracking dependencies.

Core and Builtins

  • gh-107901: Compiler duplicates basic blocks that have an eval breaker check, no line number, and multiple predecessors.

  • gh-107901: A jump leaving an exception handler back to normal code no longer checks the eval breaker.

  • gh-113655: Set the C recursion limit to 4000 on Windows, and 10000 on Linux/OSX. This seems to be near the sweet spot to maintain safety, but not compromise backwards compatibility.

  • gh-113710: Add typed stack effects to the interpreter DSL, along with various instruction annotations.

  • gh-77046: On Windows, file descriptors wrapping Windows handles are now created non inheritable by default (PEP 446). Patch by Zackery Spytz and Victor Stinner.

  • gh-113853: Guarantee that all executors make progress. This then guarantees that tier 2 execution always makes progress.

  • gh-113753: Fix an issue where the finalizer of PyAsyncGenASend objects might not be called if they were allocated from a free list.

  • gh-107901: Compiler changed so that synthetic jumps which are not at loop end no longer check the eval breaker.

  • 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-111488: Changed error message in case of no ‘in’ keyword after ‘for’ in list comprehensions

  • gh-113657: Fix an issue that caused important instruction pointer updates to be optimized out of tier two traces.

  • gh-113603: Fixed bug where a redundant NOP is not removed, causing an assertion to fail in the compiler in debug mode.

  • 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-113486: No longer issue spurious PY_UNWIND events for optimized calls to classes.

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

  • gh-113212: Improve super error messages.

  • gh-111375: Only use NULL in the exception stack to indicate an exception was handled. Patch by Carey Metcalfe.

  • gh-112215: Increase the C recursion limit by a factor of 3 for non-debug builds, except for webassembly and s390 platforms which are unchanged. This mitigates some regressions in 3.12 with deep recursion mixing builtin (C) and Python code.

  • gh-113054: Fixed bug where a redundant NOP is not removed, causing an assertion to fail in the compiler in debug mode.

  • 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-108866: Change the API and contract of _PyExecutorObject to return the next_instr pointer, instead of the frame, and to always execute at least one instruction.

  • gh-90350: Optimize builtin functions min() and max().

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

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

  • gh-74616: input() now raises a ValueError when output on the terminal if the prompt contains embedded null characters instead of silently truncating it.

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

  • gh-112730: Use color to highlight error locations in tracebacks. Patch by Pablo Galindo

  • 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-112660: Do not clear unexpected errors during formatting error messages for ImportError and AttributeError for modules.

  • 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-95754: Provide a better error message when accessing invalid attributes on partially initialized modules. The origin of the module being accessed is now included in the message to help with the common issue of shadowing other modules.

  • gh-112217: Add check for the type of __cause__ returned from calling the type T in raise from T.

  • 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-99606: Make code generated for an empty f-string identical to the code of an empty normal string.

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

  • gh-112320: The Tier 2 translator now tracks the confidence level for staying “on trace” (i.e. not exiting back to the Tier 1 interpreter) for branch instructions based on the number of bits set in the branch “counter”. Trace translation ends when the confidence drops below 1/3rd.

  • gh-109598: PyComplex_RealAsDouble()/PyComplex_ImagAsDouble() now tries to convert an object to a complex instance using its __complex__() method before falling back to the __float__() method. Patch by Sergey B Kirpichev.

  • 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.

  • bpo-21861: Use the object’s actual class name in _io.FileIO.__repr__(), _io._WindowsConsoleIO() and _io.TextIOWrapper.__repr__(), to make these methods subclass friendly.

  • bpo-45369: Remove LibreSSL workarounds as per PEP 644.

  • bpo-34392: Added sys._is_interned().

Library

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

  • gh-111803: plistlib now supports loading more deeply nested lists in binary format.

  • 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-108364: sqlite3.Connection.iterdump() now ensures that foreign key support is disabled before dumping the database schema, if there is any foreign key violation. Patch by Erlend E. Aasland and Mariusz Felisiak.

  • gh-113971: The zipfile.ZipInfo previously protected ._compresslevel attribute has been made public as .compress_level with the old _compresslevel name remaining available as a property to retain compatibility.

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

  • gh-113868: Added mmap.MAP_NORESERVE, mmap.MAP_NOEXTEND, mmap.MAP_HASSEMAPHORE, mmap.MAP_NOCACHE, mmap.MAP_JIT, mmap.MAP_RESILIENT_CODESIGN, mmap.MAP_RESILIENT_MEDIA, mmap.MAP_32BIT, mmap.MAP_TRANSLATED_ALLOW_EXECUTE, mmap.MAP_UNIX03 and mmap.MAP_TPRO. All of them are mmap(2) flags on macOS.

  • gh-113848: asyncio.TaskGroup() and asyncio.timeout() context managers now handle CancelledError subclasses as well as exact CancelledError.

  • 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-96037: Insert TimeoutError in the context of the exception that was raised during exiting an expired asyncio.timeout() block.

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

  • gh-113238: Add Anchor to importlib.resources (in order for the code to comply with the documentation)

  • gh-111693: asyncio.Condition.wait() now re-raises the same CancelledError instance that may have caused it to be interrupted. Fixed race condition in asyncio.Semaphore.acquire() when interrupted with a CancelledError.

  • gh-113791: Add CLOCK_MONOTONIC_RAW_APPROX and CLOCK_UPTIME_RAW_APPROX to time on macOS. These are clocks available on macOS 10.12 or later.

  • 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-113568: Raise deprecation warnings from pathlib.PurePath and not its private base class PurePathBase.

  • 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-113626: Add support for the allow_code argument in the marshal module. Passing allow_code=False prevents serialization and de-serialization of code objects which is incompatible between Python versions.

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

  • gh-113537: Support loads str in plistlib.loads().

  • gh-89850: Add default implementations of pickle.Pickler.persistent_id() and pickle.Unpickler.persistent_load() methods in the C implementation. Calling super().persistent_id() and super().persistent_load() in subclasses of the C implementation of pickle.Pickler and pickle.Unpickler classes no longer causes infinite recursion.

  • gh-113569: Indicate if there were no actual calls in unittest assert_has_calls() failure.

  • 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-113568: Raise audit events from pathlib.Path and not its private base class PathBase.

  • 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-53502: Add a new option aware_datetime in plistlib to loads or dumps aware datetime.

  • gh-113358: Fix rendering tracebacks with 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-87264: Fixed tarfile list() method to show file type.

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

  • gh-113225: Speed up pathlib.Path.glob() by using os.DirEntry.path where possible.

  • gh-113149: Improve error message when a JSON array or object contains a trailing comma. Patch by Carson Radtke.

  • gh-113117: The subprocess module can now use the os.posix_spawn() function with close_fds=True on platforms where posix_spawn_file_actions_addclosefrom_np is available. Patch by Jakub Kulik.

  • 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-113191: Add support of os.fchmod() and a file descriptor in os.chmod() on Windows.

  • gh-113188: Fix shutil.copymode() and shutil.copystat() on Windows. Previously they worked differently 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-113119: os.posix_spawn() now accepts env=None, which makes the newly spawned process use the current process environment. Patch by Jakub Kulik.

  • gh-113202: Add a strict option to batched() in the itertools module.

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

  • gh-113175: Sync with importlib_metadata 7.0, including improved type annotations, fixed issue with symlinked packages in package_distributions, added EntryPoints.__repr__, introduced the diagnose script, added Distribution.origin property, and removed deprecated EntryPoint access by numeric index (tuple behavior).

  • gh-59616: Add support of os.lchmod() and the follow_symlinks argument in os.chmod() on Windows. Note that the default value of follow_symlinks in os.lchmod() is False on Windows.

  • 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-112962: dis module functions add cache information to the Instruction instance rather than creating fake Instruction instances to represent the cache entries.

  • gh-112989: Reduce overhead to connect sockets with asyncio SelectorEventLoop.

  • gh-112970: Use closefrom() on Linux where available (e.g. glibc-2.34), rather than only FreeBSD.

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

  • gh-112540: The statistics.geometric_mean() function now returns zero for datasets containing a zero. Formerly, it would raise an exception.

  • gh-87286: Added LOG_FTP, LOG_NETINFO, LOG_REMOTEAUTH, LOG_INSTALL, LOG_RAS, and LOG_LAUNCHD tot the syslog module, all of them constants on used on macOS.

  • gh-112800: Fix asyncio SubprocessTransport.close() not to throw PermissionError when used with setuid executables.

  • gh-51944: Add the following constants to the termios module. These values are present in macOS system headers: ALTWERASE, B14400, B28800, B7200, B76800, CCAR_OFLOW, CCTS_OFLOW, CDSR_OFLOW, CDTR_IFLOW, CIGNORE, CRTS_IFLOW, EXTPROC, IUTF8, MDMBUF, NL2, NL3, NOKERNINFO, ONOEOT, OXTABS, VDSUSP, VSTATUS.

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

  • gh-94692: shutil.rmtree() now only catches OSError exceptions. Previously a symlink attack resistant version of shutil.rmtree() could ignore or pass to the error handler arbitrary exception when invalid arguments were provided.

  • gh-112736: The use of del-safe symbols in subprocess was refactored to allow for use in cross-platform build environments.

  • gh-112727: Speed up pathlib.Path.absolute(). Patch by Barney Gale.

  • gh-74690: Speedup issubclass() checks against simple runtime-checkable protocols by around 6%. Patch by Alex Waygood.

  • gh-74690: Speedup isinstance() checks by roughly 20% for runtime-checkable protocols that only have one callable member. Speedup issubclass() checks for these protocols by roughly 10%. Patch by Alex Waygood.

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

  • gh-112640: Add kwdefaults parameter to types.FunctionType to set default keyword argument values.

  • gh-112622: Ensure name parameter is passed to event loop in asyncio.create_task().

  • 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 could have due to a logic bug, instead falling back to the safe but slower fork().

    Also fixed a second 3.12.0 potential security bug. 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 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-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-112578: Fix a spurious RuntimeWarning when executing the zipfile module.

  • gh-112516: Update the bundled copy of pip to version 23.3.1.

  • gh-112510: Add readline.backend for the backend readline uses (editline or readline)

  • gh-112328: [Enum] Make EnumDict, EnumDict.member_names, EnumType._add_alias_ and EnumType._add_value_alias_ public.

  • 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-101336: Add keep_alive keyword parameter for AbstractEventLoop.create_server() and BaseEventLoop.create_server().

  • gh-63284: Added support for TLS-PSK (pre-shared key) mode to the ssl module.

  • 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-112405: Optimize pathlib.PurePath.relative_to(). Patch by Alex Waygood.

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

  • gh-112361: Speed up a small handful of pathlib methods by removing some temporary objects.

  • gh-112345: Improve error message when trying to call issubclass() against a typing.Protocol that has non-method members. Patch by Randolf Scholz.

  • gh-112137: Change dis output to display no-lineno as “–” instead of “None”.

  • gh-112332: Deprecate the exc_type field of traceback.TracebackException. Add exc_type_str to replace it.

  • gh-81620: Add extra tests for random.binomialvariate()

  • gh-112292: Fix a crash in readline when imported from a sub interpreter. Patch by Anthony Shaw

  • gh-77621: Slightly improve the import time of the pathlib module by deferring some imports. Patch by Barney Gale.

  • gh-112137: Change dis output to display logical labels for jump targets instead of offsets.

  • gh-112139: Add Signature.format() to format signatures to string with extra options. And use it in pydoc to render more readable signatures that have new lines between parameters.

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

  • gh-106922: Display multiple lines with traceback when errors span multiple lines.

  • gh-111874: When creating a typing.NamedTuple class, ensure __set_name__() is called on all objects that define __set_name__ and exist in the values of the NamedTuple class’s class dictionary. Patch by Alex Waygood.

  • gh-68166: Add support of the “vsapi” element type in tkinter.ttk.Style.element_create().

  • gh-110275: Named tuple’s methods _replace() and __replace__() now raise TypeError instead of ValueError for invalid keyword arguments.

  • gh-99367: Do not mangle sys.path[0] in pdb if safe_path is set

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

  • 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-67790: Implement basic formatting support (minimum width, alignment, fill) for fractions.Fraction.

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

  • gh-102980: Redirect the output of interact command of pdb to the same channel as the debugger. Add tests and improve docs.

  • 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 parameter is available. Patch by Thomas Dwyer and Victor Stinner to improve the CVE 2023-27043 fix.

  • gh-52161: cmd.Cmd.do_help() now cleans docstrings with inspect.cleandoc() before writing them. Patch by Filip Łapkiewicz.

  • gh-82300: Add track parameter to multiprocessing.shared_memory.SharedMemory that allows using shared memory blocks without having to register with the POSIX resource tracker that automatically releases them upon process exit.

  • gh-110109: Add private pathlib._PurePathBase class: a base class for pathlib.PurePath that omits certain magic methods. It may be made public (along with _PathBase) in future.

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

  • gh-91539: Small (10 - 20%) and trivial performance improvement of urllib.request.getproxies_environment(), typically useful when there are many environment variables to go over.

  • gh-103363: Add follow_symlinks keyword-only argument to pathlib.Path.owner() and group(), defaulting to True.

  • gh-102130: Support tab completion in cmd for editline.

  • 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.

  • gh-104003: Add warnings.deprecated(), a decorator to mark deprecated functions to static type checkers and to warn on usage of deprecated classes and functions. See PEP 702. Patch by Jelle Zijlstra.

  • gh-103708: Make hardcoded python name, a configurable parameter so that different implementations of python can override it instead of making huge diffs in sysconfig.py

  • gh-66515: mailbox.MH now supports folders that do not contain a .mh_sequences file (e.g. Claws Mail IMAP-cache folders). Patch by Serhiy Storchaka.

  • gh-83162: Renamed re.error to PatternError for clarity, and kept re.error for backward compatibility. Patch by Matthias Bussonnier and Adam Chhina.

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

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

  • bpo-32731: getpass.getuser() now raises OSError for all failures rather than ImportError on systems lacking the pwd module or KeyError if the password database is empty.

  • bpo-34321: mmap.mmap now has a trackfd parameter on Unix; if it is False, the file descriptor specified by fileno will not be duplicated.

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

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

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

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

  • bpo-19821: The pydoc.ispackage() function has been deprecated.

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

  • bpo-39912: warnings.filterwarnings() and warnings.simplefilter() now raise appropriate exceptions instead of AssertionError. Patch contributed by Rémi Lapeyre.

  • bpo-37260: Fixed a race condition in shutil.rmtree() in which directory entries removed by another process or thread while shutil.rmtree() is running can cause it to raise FileNotFoundError. 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.

  • bpo-29779: Add a new PYTHON_HISTORY environment variable to set the location of a .python_history file.

  • bpo-21360: mailbox.Maildir now ignores files with a leading dot.

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-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-111798: Disable test_super_deep() from test_call under pydebug builds on WASI; the stack depth is too small to make the test useful.

  • gh-111801: Lower the recursion limit in test_isinstance for test_infinitely_many_bases(). This prevents a stack overflow on a pydebug build of WASI.

  • gh-111802: Specify a low recursion depth for test_bad_getattr() in test.pickletester to avoid exhausting the stack under a pydebug build for WASI.

  • gh-44626: Fix os.path.isabs() incorrectly returning True when given a path that starts with exactly one (back)slash on Windows.

    Fix pathlib.PureWindowsPath.is_absolute() incorrectly returning False for some paths beginning with two (back)slashes.

  • gh-113633: Use module state for the _testcapi extension module.

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

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

  • gh-112334: Adds a regression test to verify that vfork() is used when expected by subprocess on vfork enabled POSIX systems (Linux).

  • 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.

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

Build

  • gh-114013: Fix Tools/wasm/wasi.py to not include the path to python.wasm as part of HOSTRUNNER. The environment variable is meant to specify how to run the WASI host only, having python.wasm and relevant flags appended to the HOSTRUNNER. This fixes make test work.

  • gh-113258: Changed the Windows build to write out generated frozen modules into the build tree instead of the source tree.

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

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

  • gh-103065: Introduce Tools/wasm/wasi.py to simplify doing a WASI build.

  • 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-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-111973: Update Windows installer to use SQLite 3.44.2.

  • 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-86179: Fixes path calculations when launching Python on Windows through a symlink.

  • gh-71383: Update Tcl/Tk in Windows installer to 8.6.13 with a patch to suppress incorrect ThemeChanged warnings.

  • gh-111650: Ensures the Py_GIL_DISABLED preprocessor variable is defined in pyconfig.h so that extension modules written in C are able to use it.

  • gh-112278: Reduce the time cost for some functions in platform on Windows if current user has no permission to the WMI.

  • gh-73427: Deprecate sys._enablelegacywindowsfsencoding(). Use PYTHONLEGACYWINDOWSFSENCODING instead. Patch by Inada Naoki.

  • 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-113666: Add the following constants to module stat: UF_SETTABLE, UF_TRACKED, UF_DATAVAULT, SF_SUPPORTED, SF_SETTABLE, SF_SYNTHETIC, SF_RESTRICTED, SF_FIRMLINK and SF_DATALESS. The values UF_SETTABLE, SF_SUPPORTED, SF_SETTABLE and SF_SYNTHETIC are only available on macOS.

  • gh-113536: os.waitid() is now available on macOS

  • 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-87277: webbrowser: Don’t look for X11 browsers on macOS. Those are generally not used and probing for them can result in starting XQuartz even if it isn’t used otherwise.

  • gh-111973: Update macOS installer to use SQLite 3.44.2.

  • 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.

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

IDLE

  • gh-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.

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

C API

Python 3.13.0 alpha 2

Release date: 2023-11-22

Core and Builtins

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

  • gh-112287: Slightly optimize the Tier 2 (uop) interpreter by only loading oparg and operand when needed. Also double the trace size limit again, to 512 this time.

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

  • gh-111807: Lower the max parser stack depth to 1000 under WASI debug builds.

  • gh-111798: When Python is built in debug mode, set the C recursion limit to 500 instead of 1500. A debug build is likely built with low optimization level which implies higher stack memory usage than a release build. Patch by Victor Stinner.

  • gh-106529: Enable translating unspecialized FOR_ITER to Tier 2.

  • gh-111916: Make hashlib related modules thread-safe without the GIL

  • gh-81137: Deprecate assignment to a function’s __code__ field when the new code object is of a mismatched type (e.g., from a generator to a plain function).

  • gh-79932: Raise exception if frame.clear() is called on a suspended frame.

  • gh-81925: Implement native thread ids for GNU KFreeBSD.

  • gh-111843: Use exponential backoff to reduce the number of failed tier 2 optimization attempts by over 99%.

  • gh-110829: Joining a thread now ensures the underlying OS thread has exited. This is required for safer fork() in multi-threaded processes.

  • gh-109369: Make sure that tier 2 traces are de-optimized if the code is instrumented

  • gh-111772: Specialize slot loads and stores for _Py_T_OBJECT as well as Py_T_OBJECT_EX

  • gh-111666: Speed up BaseExceptionGroup.derive(), BaseExceptionGroup.subgroup(), and BaseExceptionGroup.split() by changing how they parse passed arguments.

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

  • gh-111623: Add support for sharing tuples between interpreters using the cross-interpreter API. Patch by Anthony Shaw.

  • gh-111354: The oparg of YIELD_VALUE is now 1 if the instruction is part of a yield-from or await, and 0 otherwise.

    The SUSPENDED frame state is now split into SUSPENDED and SUSPENDED_YIELD_FROM. This simplifies the code in _PyGen_yf.

  • gh-111520: Merge the Tier 1 (bytecode) and Tier 2 (micro-ops) interpreters together, moving the Tier 2 interpreter loop and switch into _PyEval_EvalFrameDefault() in Python/ceval.c. The Python/executor.c file is gone. Also the TIER_ONE and TIER_TWO macros are now handled by the code generator.

    Beware! This changes the environment variables to enable micro-ops and their debugging to PYTHON_UOPS and PYTHON_LLTRACE.

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

  • gh-111420: Allow type comments in parenthesized with statements

  • gh-111438: Add support for sharing floats between interpreters using the cross-interpreter API. Patch by Anthony Shaw.

  • gh-111435: Add support for sharing of True and False between interpreters using the cross-interpreter API. Patch by Anthony Shaw.

  • 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-111374: Added a new environment variable PYTHON_FROZEN_MODULES. It determines whether or not frozen modules are ignored by the import machinery, equivalent of the -X frozen_modules command-line option.

  • gh-111354: Remove oparg from YIELD_VALUE. Change oparg of RESUME to include information about the except-depth. These changes make it possible to simplify the code in generator close.

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

  • gh-67224: Show source lines in tracebacks when using the -c option when running Python. Patch by Pablo Galindo

  • gh-111123: Fix a bug where a global declaration in an except block is rejected when the global is used in the else block.

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

  • gh-109214: Remove unnecessary instruction pointer updates before returning from frames.

  • gh-110912: Correctly display the traceback for MemoryError exceptions using the traceback module. Patch by Pablo Galindo

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

  • gh-110892: Return NULL for PyTrace_RETURN events caused by an exception

  • gh-110864: Fix argument parsing by _PyArg_UnpackKeywordsWithVararg for functions defining pos-or-keyword, vararg, and kw-only parameters.

  • gh-109094: Replace prev_instr on the interpreter frame by instr_ptr which points to the beginning of the instruction that is currently executing (or will execute once the frame resumes).

  • gh-110805: Allow the repl to show source code and complete tracebacks. Patch by Pablo Galindo

  • gh-110722: Add PYTHON_PRESITE=package.module to import a module early in the interpreter lifecycle before site.py is executed. Python needs to be built in debug mode for this option to exist.

  • gh-110481: Implement biased reference counting in --disable-gil builds.

  • 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-89519: Removed chained classmethod descriptors (introduced in bpo-19072). This can no longer be used to wrap other descriptors such as property. The core design of this feature was flawed and caused a number of downstream problems. To “pass-through” a classmethod, consider using the __wrapped__ attribute that was added in Python 3.10.

  • gh-103615: Use local events for opcode tracing

  • bpo-46657: Add mimalloc memory allocator support.

  • gh-106718: When PyConfig.stdlib_dir is explicitly set, it’s now respected and won’t be overridden by PyConfig.home.

  • gh-106905: Fix incorrect SystemError about AST constructor recursion depth mismatch.

  • gh-100445: Improve error message for unterminated strings with escapes.

  • bpo-45759: Improved error messages for elif/else statements not matching any valid statements. Patch by Jeremiah Vivian.

Library

Tests

  • gh-111808: Make the default value of test.support.infinite_recursion() to be conditional based on whether optimizations were used when compiling the interpreter. This helps with platforms like WASI whose stack size is greatly restricted in debug builds.

  • gh-110722: Gathering line coverage of standard libraries within the regression test suite is now precise, as well as much faster. Patch by Łukasz Langa.

  • 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-108747: Add unit test for usercustomize and sitecustomize hooks from site.

Build

  • gh-96954: Make make regen-unicodedata work for out-of-tree builds of CPython.

  • gh-112088: Add Tools/build/regen-configure.