Changelog

Python next

Release date: XXXX-XX-XX

Security

Core and Builtins

  • 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-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-101860: Expose __name__ attribute on property.

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

Library

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

  • 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-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-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-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.

Documentation

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

Tests

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

  • 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 hander targets by _testinternalcapi.optimize_cfg.

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

Build

  • 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.

Windows

  • 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.

Tools/Demos

  • gh-100176: Remove outdated Tools/{io,cc,string}bench

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.

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 accomodate 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.aquire() 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 differenly if dst is a symbolic link: they modified the permission bits of dst itself rather than the file it points to if follow_symlinks is true or src is not a symbolic link, and did not modify the permission bits if follow_symlinks is false and src is a symbolic link.

  • gh-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 paramater 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 urrlib.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.sh script to regenerate the configure with an Ubuntu container image. The quay.io/tiran/cpython_autoconf:271 container image (tiran/cpython_autoconf) is no longer used. Patch by Victor Stinner.

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

  • gh-110828: AIX 32bit needs -latomic to build the _testcapi extension module.

  • gh-85283: The errno, md5, resource, winsound, _ctypes_test, _multiprocessing.posixshmem, _scproxy, _stat, _testimportmultiple and _uuid C extensions are now built with the limited C API. Patch by Victor Stinner.

Windows

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

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

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

macOS

  • gh-59703: For macOS framework builds, in getpath.c use the system dladdr function to find the path to the shared library rather than depending on deprecated macOS APIs.

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

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

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

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

IDLE

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

Tools/Demos

  • gh-111903: Argument Clinic now supports the @critical_section directive that instructs Argument Clinic to generate a critical section around the function call, which locks the self object in --disable-gil builds. Patch by Sam Gross.

C API

  • gh-112026: Add again the private _PyThreadState_UncheckedGet() function as an alias to the new public PyThreadState_GetUnchecked() function. Patch by Victor Stinner.

  • gh-112026: Restore the removed _PyDict_GetItemStringWithError() function. It is used by numpy. Patch by Victor Stinner.

  • gh-112026: Restore removed private C API functions, macros and structures which have no simple replacement for now:

    • _PyDict_GetItem_KnownHash()

    • _PyDict_NewPresized()

    • _PyHASH_BITS

    • _PyHASH_IMAG

    • _PyHASH_INF

    • _PyHASH_MODULUS

    • _PyHASH_MULTIPLIER

    • _PyLong_Copy()

    • _PyLong_FromDigits()

    • _PyLong_New()

    • _PyLong_Sign()

    • _PyObject_CallMethodId()

    • _PyObject_CallMethodNoArgs()

    • _PyObject_CallMethodOneArg()

    • _PyObject_CallOneArg()

    • _PyObject_EXTRA_INIT

    • _PyObject_FastCallDict()

    • _PyObject_GetAttrId()

    • _PyObject_Vectorcall()

    • _PyObject_VectorcallMethod()

    • _PyStack_AsDict()

    • _PyThread_CurrentFrames()

    • _PyUnicodeWriter structure

    • _PyUnicodeWriter_Dealloc()

    • _PyUnicodeWriter_Finish()

    • _PyUnicodeWriter_Init()

    • _PyUnicodeWriter_Prepare()

    • _PyUnicodeWriter_PrepareKind()

    • _PyUnicodeWriter_WriteASCIIString()

    • _PyUnicodeWriter_WriteChar()

    • _PyUnicodeWriter_WriteLatin1String()

    • _PyUnicodeWriter_WriteStr()

    • _PyUnicodeWriter_WriteSubstring()

    • _PyUnicode_AsString()

    • _PyUnicode_FromId()

    • _PyVectorcall_Function()

    • _Py_IDENTIFIER()

    • _Py_c_abs()

    • _Py_c_diff()

    • _Py_c_neg()

    • _Py_c_pow()

    • _Py_c_prod()

    • _Py_c_quot()

    • _Py_c_sum()

    • _Py_static_string()

    • _Py_static_string_init()

    Patch by Victor Stinner.

  • gh-112026: Add again <ctype.h> and <unistd.h> includes in Python.h, but don’t include them in the limited C API version 3.13 and newer. Patch by Victor Stinner.

  • gh-111956: Add internal-only one-time initialization API: _PyOnceFlag and _PyOnceFlag_CallOnce.

  • gh-111262: Add PyDict_Pop() and PyDict_PopString() functions: remove a key from a dictionary and optionally return the removed value. This is similar to dict.pop(), but without the default value and not raising KeyError if the key missing. Patch by Stefan Behnel and Victor Stinner.

  • gh-111863: Rename Py_NOGIL to Py_GIL_DISABLED. Patch by Hugo van Kemenade.

  • gh-111138: Add PyList_Extend() and PyList_Clear() functions: similar to Python list.extend() and list.clear() methods. Patch by Victor Stinner.

  • gh-108765: On Windows, Python.h no longer includes the <stddef.h> standard header file. If needed, it should now be included explicitly. Patch by Victor Stinner.

  • gh-111569: Implement “Python Critical Sections” from PEP 703. These are macros to help replace the GIL with per-object locks in the --disable-gil build of CPython. The macros are no-ops in the default build.

  • gh-111506: In the limited C API version 3.13, Py_SET_REFCNT() function is now implemented as an opaque function call. Patch by Victor Stinner.

  • gh-108082: Add PyErr_FormatUnraisable() function.

  • gh-110964: Move the undocumented private _PyArg functions and _PyArg_Parser structure to internal C API (pycore_modsupport.h). Patch by Victor Stinner.

  • gh-110815: Support non-ASCII keyword names in PyArg_ParseTupleAndKeywords().

  • gh-109587: Introduced PyUnstable_PerfTrampoline_CompileCode(), PyUnstable_PerfTrampoline_SetPersistAfterFork() and PyUnstable_CopyPerfMapFile(). These functions allow extension modules to initialize trampolines eagerly, after the application is “warmed up”. This makes it possible to have perf-trampolines running in an always-enabled fashion.

  • gh-85283: Add the PySys_Audit() function to the limited C API. Patch by Victor Stinner.

  • gh-85283: Add PyMem_RawMalloc(), PyMem_RawCalloc(), PyMem_RawRealloc() and PyMem_RawFree() to the limited C API. Patch by Victor Stinner.

  • gh-106672: Functions PyDict_GetItem(), PyDict_GetItemString(), PyMapping_HasKey(), PyMapping_HasKeyString(), PyObject_HasAttr(), PyObject_HasAttrString(), and PySys_GetObject(), which clear all errors occurred during calling the function, report now them using sys.unraisablehook().

  • gh-67565: Remove redundant C-contiguity check in getargs.c, binascii, ssl and Argument Clinic. Patched by Stefan Krah and Furkan Onder

Python 3.13.0 alpha 1

Release date: 2023-10-13

Security

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

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

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

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

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

Core and Builtins

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

  • gh-110752: Reset ceval.eval_breaker in interpreter_clear()

  • gh-110721: Use the traceback implementation for the default PyErr_Display() functionality. Patch by Pablo Galindo

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

  • gh-104169: Split the tokenizer into two separate directories: - One part includes the actual lexeme producing logic and lives in Parser/lexer. - The second part wraps the lexer according to the different tokenization modes we have (string, utf-8, file, interactive, readline) and lives in Parser/tokenizer.

  • gh-110688: Remove undocumented test_c_api method from set, which was only defined for testing purposes under Py_DEBUG. Now we have proper CAPI tests.

  • gh-104584: Fix a reference leak when running with PYTHONUOPS or -X uops enabled.

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

  • gh-110489: Optimise math.ceil() when the input is exactly a float, resulting in about a 10% improvement.

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

  • gh-110309: Remove unnecessary empty constant nodes in the ast of f-string specs.

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

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

  • gh-110164: regrtest: If the SOURCE_DATE_EPOCH environment variable is defined, regrtest now disables tests randomization. Patch by Victor Stinner.

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

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

  • gh-109923: Set line number on the POP_TOP that follows a RETURN_GENERATOR.

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

  • gh-109369: The internal eval_breaker and supporting flags, plus the monitoring version have been merged into a single atomic integer to speed up checks.

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

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

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

  • gh-109595: Add -X cpu_count command line option to override return results of os.cpu_count() and os.process_cpu_count(). This option is useful for users who need to limit CPU resources of a container system without having to modify the container (application code). Patch by Donghee Na.

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

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

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

  • gh-107265: Deopt opcodes hidden by the executor when base opcode is needed

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

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

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

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

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

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

  • gh-109256: Opcode IDs for specialized opcodes are allocated in their own range to improve stability of the IDs for the ‘real’ opcodes.

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

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

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

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

  • gh-109156: Add tests for de-instrumenting instructions while keeping the instrumentation for lines

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

  • gh-105848: Add a new CALL_KW opcode, used for calls containing keyword arguments. Also, fix a possible crash when jumping over method calls in a debugger.

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

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

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

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

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

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

  • gh-104584: Fix a crash when running with PYTHONUOPS or -X uops enabled and an error occurs during optimization.

  • gh-108727: Define tp_dealloc for CounterOptimizer_Type. This fixes a segfault on deallocation.

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

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

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

  • gh-108488: Change the initialization of inline cache entries so that the cache entry for JUMP_BACKWARD is initialized to zero, instead of the adaptive_counter_warmup() value used for all other instructions. This counter, unique among instructions, counts up from zero.

  • gh-108716: Turn off deep-freezing of code objects. Modules are still frozen, so that a file system search is not needed for common modules.

  • gh-108614: Add RESUME_CHECK instruction, to avoid having to handle instrumentation, signals, and contexts switches in the tier 2 execution engine.

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

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

  • gh-105481: The regen-opcode build stage was removed and its work is now done in regen-cases.

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

  • gh-108113: The compile() built-in can now accept a new flag, ast.PyCF_OPTIMIZED_AST, which is similar to ast.PyCF_ONLY_AST except that the returned AST is optimized according to the value of the optimize argument.

    ast.parse() now accepts an optional argument optimize which is passed on to the compile() built-in. This makes it possible to obtain an optimized AST.

  • gh-107971: Opcode IDs are generated from bytecodes.c instead of being hard coded in opcode.py.

  • gh-107944: Improve error message for function calls with bad keyword arguments. Patch by Pablo Galindo

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

    Fixes crash when tracing in recursive calls to Python classes.

  • gh-108035: Remove the _PyCFrame struct, moving the pointer to the current intepreter frame back to the threadstate, as it was for 3.10 and earlier. The _PyCFrame existed as a performance optimization for tracing. Since PEP 669 has been implemented, this optimization no longer applies.

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

  • gh-106581: Fix possible assertion failures and missing instrumentation events when PYTHONUOPS or -X uops is enabled.

  • gh-107526: Revert converting vars, dir, next, getattr, and iter to argument clinic.

  • gh-84805: Autogenerate signature for METH_NOARGS and METH_O extension functions.

  • gh-107758: Make the dump_stack() routine used by the lltrace feature (low-level interpreter debugging) robust against recursion by ensuring that it never calls a __repr__ method implemented in Python. Also make the similar output for Tier-2 uops appear on stdout (instead of stderr), to match the lltrace code in ceval.c.

  • gh-107659: Add docstrings for ctypes.pointer() and ctypes.POINTER().

  • gh-105848: Modify the bytecode so that the actual callable for a CALL is at a consistent position on the stack (regardless of whether or not bound-method-calling optimizations are active).

  • gh-107674: Fixed performance regression in sys.settrace.

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

  • gh-84436: Skip reference count modifications for many known immortal objects.

  • gh-107596: Specialize subscripting str objects by int indexes.

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

  • gh-107557: Generate the cases needed for the barebones tier 2 abstract interpreter for optimization passes in CPython.

  • gh-106608: Make _PyUOpExecutorObject variable length.

  • gh-100964: Clear generators’ exception state after return to break reference cycles.

  • gh-107455: Improve error messages when converting an incompatible type to ctypes.c_char_p, ctypes.c_wchar_p and ctypes.c_void_p.

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

  • gh-104584: Fix an issue which caused incorrect inline caches to be read when running with PYTHONUOPS or -X uops enabled.

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

  • gh-106078: Isolate _decimal (apply PEP 687). Patch by Charlie Zhao.

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

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

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

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

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

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

  • gh-107122: Add dbm.ndbm.ndbm.clear() to dbm.ndbm. Patch By Donghee Na.

  • gh-107122: Add dbm.gnu.gdbm.clear() to dbm.gnu. Patch By Donghee Na.

  • gh-107015: The ASYNC and AWAIT tokens are removed from the Grammar, which removes the posibility of making async and await soft keywords when using feature_version<7 in ast.parse().

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

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

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

  • gh-106908: Fix various hangs, reference leaks, test failures, and tracing/introspection bugs when running with PYTHONUOPS or -X uops enabled.

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

  • gh-106485: Reduce the number of materialized instances dictionaries by dematerializing them when possible.

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

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

  • gh-104909: Split LOAD_ATTR_INSTANCE_VALUE into micro-ops.

  • gh-104909: Split LOAD_GLOBAL specializations into micro-ops.

  • gh-106597: A new debug structure of offsets has been added to the _PyRuntimeState that will help out-of-process debuggers and profilers to obtain the offsets to relevant interpreter structures in a way that is agnostic of how Python was compiled and that doesn’t require copying the headers. Patch by Pablo Galindo

  • gh-106487: Allow the count argument of str.replace() to be a keyword. Patch by Hugo van Kemenade.

  • gh-96844: Improve error message of list.remove(). Patch by Donghee Na.

  • gh-81283: Compiler now strips indents from docstrings. It reduces pyc file size 5% when the module is heavily documented. This change affects to __doc__ so tools like doctest will be affected.

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

  • gh-100288: Specialize LOAD_ATTR for non-descriptors on the class. Adds LOAD_ATTR_NONDESCRIPTOR_WITH_VALUES and LOAD_ATTR_NONDESCRIPTOR_NO_DICT.

  • gh-106008: Fix possible reference leaks when failing to optimize comparisons with None in the bytecode compiler.

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

  • gh-106213: Changed the way that Emscripten call trampolines work for compatibility with Wasm/JS Promise integration.

  • gh-106182: sys.getfilesystemencoding() and sys.getfilesystemencodeerrors now return interned Unicode object.

  • gh-106210: Removed Emscripten import trampoline as it was no longer necessary for Pyodide.

  • gh-104584: Added a new, experimental, tracing optimizer and interpreter (a.k.a. “tier 2”). This currently pessimizes, so don’t use yet – this is infrastructure so we can experiment with optimizing passes. To enable it, pass -Xuops or set PYTHONUOPS=1. To get debug output, set PYTHONUOPSDEBUG=N where N is a debug level (0-4, where 0 is no debug output and 4 is excessively verbose).

  • gh-105775: LOAD_CLOSURE is now a pseudo-op.

  • gh-105730: Allow any callable other than type objects as the condition predicate in BaseExceptionGroup.split() and BaseExceptionGroup.subgroup().

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

  • gh-106003: Add a new TO_BOOL instruction, which performs boolean conversions for POP_JUMP_IF_TRUE, POP_JUMP_IF_FALSE, and UNARY_NOT (which all expect exact bool values now). Also, modify the oparg of COMPARE_OP to include an optional “boolean conversion” flag.

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

  • gh-105724: Improve assert error messages by providing exact error range.

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

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

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

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

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

  • gh-105331: Raise ValueError if the delay argument to asyncio.sleep() is a NaN (matching time.sleep()).

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

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

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

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

  • gh-100987: Allow objects other than code objects as the “executable” in internal frames. In the long term, this can help tools like Cython and PySpy interact more efficiently. In the shorter term, it allows us to perform some optimizations more simply.

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

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

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

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

  • gh-105678: Break the MAKE_FUNCTION instruction into two parts, MAKE_FUNCTION which makes the function and SET_FUNCTION_ATTRIBUTE which sets the attributes on the function. This makes the stack effect of MAKE_FUNCTION regular to ease optimization and code generation.

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

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

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

  • gh-104635: Eliminate redundant STORE_FAST instructions in the compiler. Patch by Donghee Na and Carl Meyer.

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

  • gh-33092: Simplify and speed up interpreter for f-strings. Removes FORMAT_VALUE opcode. Add CONVERT_VALUE, FORMAT_SIMPLE and FORMAT_WITH_SPEC opcode. Compiler emits more efficient sequence for each format expression.

  • gh-105229: Remove remaining two-codeunit superinstructions. All remaining superinstructions only take a single codeunit, simplifying instrumentation and quickening.

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

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

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

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

  • gh-105229: Replace some dynamic superinstructions with single instruction equivalents.

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

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

  • gh-105148: Make _PyASTOptimizeState internal to ast_opt.c. Make _PyAST_Optimize take two integers instead of a pointer to this struct. This avoids the need to include pycore_compile.h in ast_opt.c.

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

  • gh-105111: Remove the old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

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

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

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

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

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

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

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

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

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

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

  • gh-104770: If a generator returns a value upon being closed, the value is now returned by generator.close().

  • gh-89091: Raise RuntimeWarning for unawaited async generator methods like asend(), athrow() and aclose(). Patch by Kumar Aditya.

  • gh-96663: Add a better, more introspect-able error message when setting attributes on classes without a __dict__ and no slot member for the attribute.

  • gh-93627: Update the Python pickle module implementation to match the C implementation of the pickle module. For objects setting reduction methods like __reduce_ex__() or __reduce__() to None, pickling will result in a TypeError.

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

  • gh-91095: Specializes calls to most Python classes. Specifically, any class that inherits from object, or another Python class, and does not override __new__.

    The specialized instruction does the following:

    1. Creates the object (by calling object.__new__)

    2. Pushes a shim frame to the frame stack (to cleanup after __init__)

    3. Pushes the frame for __init__ to the frame stack

    Speeds up the instantiation of most Python classes.

Library

  • gh-110786: sysconfig’s CLI now ignores BrokenPipeError, making it exit normally if its output is being piped and the pipe closes.

  • gh-103480: The sysconfig module is now a package, instead of a single-file module.

  • gh-110733: Micro-optimization: Avoid calling min(), max() in BaseEventLoop._run_once().

  • gh-94597: Added asyncio.EventLoop for use with the asyncio.run() loop_factory kwarg to avoid calling the asyncio policy system.

  • gh-110682: runtime-checkable protocols used to consider __match_args__ a protocol member in __instancecheck__ if it was present on the protocol. Now, this attribute is ignored if it is present.

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

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

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

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

  • gh-89902: Deprecate non-standard format specifier “N” for decimal.Decimal. It was not documented and only supported in the C implementation.

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

  • gh-106670: In pdb, set convenience variable $_exception for post mortem debugging.

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

  • gh-109653: Slightly improve the import time of several standard-library modules by deferring imports of warnings within those modules. Patch by Alex Waygood.

  • gh-110273: dataclasses.replace() now raises TypeError instead of ValueError if specify keyword argument for a field declared with init=False or miss keyword argument for required InitVar field.

  • gh-110249: Add --inline-caches flag to dis command line.

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

  • gh-110222: Add support of struct sequence objects in copy.replace(). Patched by Xuehai Pan.

  • gh-109649: multiprocessing, concurrent.futures, compileall: Replace os.cpu_count() with os.process_cpu_count() to select the default number of worker threads and processes. Get the CPU affinity if supported. Patch by Victor Stinner.

  • gh-110150: Fix base case handling in statistics.quantiles. Now allows a single data point.

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

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

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

  • gh-88402: Add new variables to sysconfig.get_config_vars() on Windows: LIBRARY, LDLIBRARY, LIBDIR, SOABI, and Py_NOGIL.

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

  • gh-109653: Reduce the import time of email.utils by around 43%. This results in the import time of email.message falling by around 18%, which in turn reduces the import time of importlib.metadata by around 6%. Patch by Alex Waygood.

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

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

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

  • gh-109653: Improve import time of functools by around 13%. Patch by Alex Waygood.

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

  • gh-109653: Reduce the import time of enum by over 50%. Patch by Alex Waygood.

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

  • gh-109653: Reduce the import time of typing by around a third. Patch by Alex Waygood.

  • gh-109649: Add os.process_cpu_count() function to get the number of logical CPUs usable by the calling thread of the current process. Patch by Victor Stinner.

  • gh-74481: Add set_error_mode related constants in msvcrt module in Python debug build.

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

  • gh-109599: Expose the type of PyCapsule objects as types.CapsuleType.

  • gh-109109: You can now get the raw TLS certificate chains from TLS connections via ssl.SSLSocket.get_verified_chain() and ssl.SSLSocket.get_unverified_chain() methods.

    Contributed by Mateusz Nowak.

  • gh-109559: Update unicodedata database to Unicode 15.1.0.

  • gh-109543: Remove unnecessary hasattr() check during typing.TypedDict creation.

  • gh-109495: Remove unnecessary extra __slots__ in datetime's pure python implementation to reduce memory size, as they are defined in the superclass. Patch by James Hilton-Balfe

  • gh-109461: logging: Use a context manager for lock acquisition.

  • gh-109096: http.server.CGIHTTPRequestHandler has been deprecated for removal in 3.15. Its design is old and the web world has long since moved beyond CGI.

  • gh-109409: Fix error when it was possible to inherit a frozen dataclass from multiple parents some of which were possibly not frozen.

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

  • gh-109319: Deprecate the dis.HAVE_ARGUMENT field in favour of dis.hasarg.

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

  • gh-66143: The codecs.CodecInfo object has been made copyable and pickleable. Patched by Robert Lehmann and Furkan Onder.

  • gh-109187: pathlib.Path.resolve() now treats symlink loops like other errors: in strict mode, OSError is raised, and in non-strict mode, no exception is raised.

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

  • gh-109174: Add support of types.SimpleNamespace in copy.replace().

  • gh-109164: pdb: Replace getopt with argparse for parsing command line arguments.

  • gh-109151: Enable readline editing features in the sqlite3 command-line interface (python -m sqlite3).

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

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

  • gh-109033: Exceptions raised by os.utime builtin function now include the related filename

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

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

  • gh-108751: Add copy.replace() function which allows to create a modified copy of an object. It supports named tuples, dataclasses, and many other objects.

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

  • gh-108278: Deprecate passing the callback callable by keyword for the following sqlite3.Connection APIs:

    The affected parameters will become positional-only in Python 3.15.

    Patch by Erlend E. Aasland.

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

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

  • gh-108463: Make expressions/statements work as expected in pdb

  • gh-108277: Add os.timerfd_create(), os.timerfd_settime(), os.timerfd_gettime(), os.timerfd_settime_ns(), and os.timerfd_gettime_ns() to provide a low level interface for Linux’s timer notification file descriptor.

  • gh-107811: tarfile: extraction of members with overly large UID or GID (e.g. on an OS with 32-bit id_t) now fails in the same way as failing to set the ID.

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

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

  • gh-108294: time.sleep() now raises an auditing event.

  • gh-108278: Deprecate passing name, number of arguments, and the callable as keyword arguments, for the following sqlite3.Connection APIs:

    The affected parameters will become positional-only in Python 3.15.

    Patch by Erlend E. Aasland.

  • gh-108322: Speed-up NormalDist.samples() by using the inverse CDF method instead of calling random.gauss().

  • gh-83417: Add the ability for venv to create a .gitignore file which causes the created environment to be ignored by Git. It is on by default when venv is called via its CLI.

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

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

  • gh-107932: Fix dis module to properly report and display bytecode that do not have source lines.

  • gh-105539: sqlite3 now emits an ResourceWarning if a sqlite3.Connection object is not closed explicitly. Patch by Erlend E. Aasland.

  • gh-107995: The __module__ attribute on instances of functools.cached_property is now set to the name of the module in which the cached_property is defined, rather than “functools”. This means that doctests in cached_property docstrings are now properly collected by the doctest module. Patch by Tyler Smart.

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

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

  • gh-81555: xml.dom.minidom now only quotes " in attributes.

  • gh-50002: xml.dom.minidom now preserves whitespaces in attributes.

  • gh-93057: Passing more than one positional argument to sqlite3.connect() and the sqlite3.Connection constructor is deprecated. The remaining parameters will become keyword-only in Python 3.15. Patch by Erlend E. Aasland.

  • gh-76913: Add merge_extra parameter/feature to logging.LoggerAdapter

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

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

  • gh-107812: Extend socket’s netlink support to the FreeBSD platform.

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

  • gh-107782: pydoc is now able to show signatures which are not representable in Python, e.g. for getattr and dict.pop.

  • gh-56166: Deprecate passing optional arguments maxsplit, count and flags in module-level functions re.split(), re.sub() and re.subn() as positional. They should only be passed by keyword.

  • gh-107710: Speed up logging.getHandlerNames().

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

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

  • gh-72684: Add tkinter widget methods: tk_busy_hold(), tk_busy_configure(), tk_busy_cget(), tk_busy_forget(), tk_busy_current(), and tk_busy_status().

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

  • gh-107465: Add pathlib.Path.from_uri() classmethod.

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

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

  • gh-105481: Remove opcode.is_pseudo, opcode.MIN_PSEUDO_OPCODE and opcode.MAX_PSEUDO_OPCODE, which were added in 3.12, were never documented and were not intended to be used externally.

  • gh-105481: opcode.ENABLE_SPECIALIZATION (which was added in 3.12 but never documented or intended for external usage) is moved to _opcode.ENABLE_SPECIALIZATION where tests can access it.

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

  • gh-107409: Set __wrapped__ attribute in reprlib.recursive_repr().

  • gh-107406: Implement new __repr__() method for struct.Struct. Now it returns Struct(<format repr>).

  • gh-107369: Optimize textwrap.indent(). It is ~30% faster for large input. Patch by Inada Naoki.

  • gh-78722: Fix issue where pathlib.Path.iterdir() did not raise OSError until iterated.

  • gh-105578: Deprecate typing.AnyStr in favor of the new Type Parameter syntax. See PEP 695.

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

  • gh-107089: Shelves opened with shelve.open() have a much faster clear() method. Patch by James Cave.

  • gh-82500: Fix overflow on 32-bit systems with asyncio os.sendfile() implemention.

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

  • gh-65495: Use lowercase mail from and rcpt to in smptlib.SMTP.

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

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

  • gh-106739: Add the rtype_cache to the warning message (as an addition to the type of leaked objects and the number of leaked objects already included in the message) to make debugging leaked objects easier when the multiprocessing resource tracker process finds leaked objects at shutdown. This helps more quickly identify what was leaked and/or why the leaked object was not properly cleaned up.

  • gh-106751: Optimize SelectSelector.select() for many iteration case. Patch By Donghee Na.

  • gh-106751: Optimize _PollLikeSelector.select() for many iteration case.

  • gh-106751: Optimize KqueueSelector.select() for many iteration case. Patch By Donghee Na.

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

  • gh-105481: The various opcode lists in the dis module are now generated from bytecodes.c instead of explicitly constructed in opcode.py.

  • gh-106727: Make inspect.getsource() smarter for class for same name definitions

  • gh-106789: Remove import of pprint from sysconfig.

  • gh-105726: Added __slots__ to contextlib.AbstractContextManager and contextlib.AbstractAsyncContextManager so that child classes can use __slots__.

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

  • gh-106751: selectors: Optimize EpollSelector.select() code by moving some code outside of the loop.

  • gh-106752: Fixed several bugs in zipfile.Path, including: in zipfile.Path.match(), Windows separators are no longer honored (and never were meant to be); Fixed name/suffix/suffixes/stem operations when no filename is present and the Path is not at the root of the zipfile; Reworked glob for performance and more correct matching behavior.

  • gh-105293: Remove call to SSL_CTX_set_session_id_context during client side context creation in the ssl module.

  • gh-106734: Disable tab completion in multiline mode of pdb

  • gh-105481: Expose opcode metadata through _opcode.

  • gh-106670: Add the new exceptions command to the Pdb debugger. It makes it possible to move between chained exceptions when using post mortem debugging.

  • gh-106602: Add __copy__ and __deepcopy__ in enum

  • gh-106664: selectors: Add _SelectorMapping.get() method and optimize _SelectorMapping.__getitem__().

  • gh-106628: Speed up parsing of emails by about 20% by not compiling a new regular expression for every single email.

  • gh-89427: Set the environment variable VIRTUAL_ENV_PROMPT at venv activation, even when VIRTUAL_ENV_DISABLE_PROMPT is set.

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

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

  • gh-106566: Optimize (?!) (pattern which alwais fails) in regular expressions.

  • gh-106554: selectors: Reduce Selector overhead by using a dict.get() to lookup file descriptors.

  • gh-106558: Remove ref cycle in callers of convert_to_error() by deleting result from scope in a finally block.

  • gh-100502: Add pathlib.PurePath.pathmod class attribute that stores the implementation of os.path used for low-level path operations: either posixpath or ntpath.

  • gh-106527: Reduce overhead to add and remove asyncio readers and writers.

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

  • gh-106531: Removed _legacy and the names it provided from importlib.resources: Resource, contents, is_resource, open_binary, open_text, path, read_binary, and read_text.

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

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

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

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

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

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

  • gh-89812: Add private pathlib._PathBase class, which provides experimental support for virtual filesystems, and may be made public in a future version of Python.

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

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

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

  • gh-106309: Deprecate typing.no_type_check_decorator(). No major type checker ever added support for this decorator. Patch by Alex Waygood.

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

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

  • gh-106236: Replace assert statements with raise RuntimeError in threading, so that _DummyThread cannot be joined even with -OO.

  • gh-106238: Fix rare concurrency bug in lock acquisition by the logging package.

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

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

  • gh-104527: Zipapp will now skip over apending an archive to itself.

  • gh-106046: Improve the error message from os.fspath() if called on an object where __fspath__ is set to None. Patch by Alex Waygood.

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

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

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

  • gh-89812: Add pathlib.UnsupportedOperation, which is raised instead of NotImplementedError when a path operation isn’t supported.

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

  • gh-105481: stack_effect() no longer raises an exception if an oparg is provided for an opcode that doesn’t use its arg, or when it is not provided for an opcode that does use it. In the latter case, the stack effect is returned for oparg=0.

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

  • gh-105793: Add follow_symlinks keyword-only argument to pathlib.Path.is_dir() and is_file(), defaulting to True.

  • gh-105570: Deprecate two methods of creating typing.TypedDict classes with 0 fields using the functional syntax: TD = TypedDict("TD") and TD = TypedDict("TD", None). Both will be disallowed in Python 3.15. To create a TypedDict class with 0 fields, either use class TD(TypedDict): pass or TD = TypedDict("TD", {}).

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

  • gh-105733: ctypes: Deprecate undocumented ctypes.SetPointerType() and ctypes.ARRAY() functions. Patch by Victor Stinner.

  • gh-105687: Remove deprecated re.template, re.T, re.TEMPLATE, sre_constans.SRE_FLAG_TEMPLATE.

  • gh-105684: Supporting asyncio.Task.set_name() is now mandatory for third party task implementations. The undocumented _set_task_name() function (deprecated since 3.8) has been removed. Patch by Kumar Aditya.

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

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

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

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

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

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

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

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

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

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

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

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

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

  • gh-105566: Deprecate creating a typing.NamedTuple class using keyword arguments to denote the fields (NT = NamedTuple("NT", x=int, y=str)). This will be disallowed in Python 3.15. Use the class-based syntax or the functional syntax instead.

    Two methods of creating NamedTuple classes with 0 fields using the functional syntax are also deprecated, and will be disallowed in Python 3.15: NT = NamedTuple("NT") and NT = NamedTuple("NT", None). To create a NamedTuple class with 0 fields, either use class NT(NamedTuple): pass or NT = NamedTuple("NT", []).

  • gh-105545: Remove deprecated in 3.11 webbrowser.MacOSXOSAScript._name attribute.

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

  • gh-105509: typing.Annotated is now implemented as an instance of typing._SpecialForm rather than a class. This should have no user-facing impact for users of the typing module public API.

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

  • gh-70303: Emit FutureWarning from pathlib.Path.glob() and rglob() if the given pattern ends with “**”. In a future Python release, patterns with this ending will match both files and directories. Add a trailing slash to only match directories.

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

  • gh-105382: Remove cafile, capath and cadefault parameters of the urllib.request.urlopen() function, deprecated in Python 3.6. Patch by Victor Stinner.

  • gh-105376: logging: Remove undocumented and untested Logger.warn() and LoggerAdapter.warn() methods and logging.warn() function. Deprecated since Python 3.3, they were aliases to the logging.Logger.warning() method, logging.LoggerAdapter.warning() method and logging.warning() function. Patch by Victor Stinner.

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

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

  • gh-105292: Add option to traceback.format_exception_only() to recurse into the nested exception of a BaseExceptionGroup.

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

  • gh-80480: array: Add 'w' typecode that represents Py_UCS4.

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

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

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

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

  • gh-62948: The io.IOBase finalizer now logs the close() method errors with sys.unraisablehook. Previously, errors were ignored silently by default, and only logged in Python Development Mode or on Python built on debug mode. Patch by Victor Stinner.

  • gh-105096: wave: Deprecate the getmark(), setmark() and getmarkers() methods of the wave.Wave_read and wave.Wave_write classes. They will be removed in Python 3.15. Patch by Victor Stinner.

  • gh-104992: Remove the untested and undocumented unittest.TestProgram.usageExit() method, deprecated in Python 3.11. Patch by Hugo van Kemenade.

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

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

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

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

  • gh-104773: PEP 594: Remove the audioop module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the aifc module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the uu module, deprecated in Python 3.11. Patch by Victor Stinner.

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

  • gh-104773: PEP 594: Remove the crypt module and its private _crypt extension, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the nis module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104898: Add missing __slots__ to os.PathLike.

  • gh-104773: PEP 594: Remove the xdrlib module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the nntplib module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104886: Remove the undocumented configparser.LegacyInterpolation class, deprecated in the docstring since Python 3.2, and with a deprecation warning since Python 3.11. Patch by Hugo van Kemenade.

  • gh-104786: Remove kwargs-based typing.TypedDict creation

  • gh-104876: Remove the turtle.RawTurtle.settiltangle() method, deprecated in docs since Python 3.1 and with a deprecation warning since Python 3.11. Patch by Hugo van Kemenade.

  • gh-104773: PEP 594: Removed the msilib package, deprecated in Python 3.11.

  • gh-104773: PEP 594: Remove the spwd module, deprecated in Python 3.11: the python-pam project can be used instead. Patch by Victor Stinner.

  • gh-75552: Removed the tkinter.tix module, deprecated since Python 3.6.

  • gh-104773: PEP 594: Remove the chunk module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the mailcap module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the sunau module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104780: PEP 594: Remove the ossaudiodev module, deprecated in Python 3.11. Patch Victor Stinner.

  • gh-104773: PEP 594: Remove the pipes module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104873: Add typing.get_protocol_members() to return the set of members defining a typing.Protocol. Add typing.is_protocol() to check whether a class is a typing.Protocol. Patch by Jelle Zijlstra.

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

  • gh-104835: Removed the following unittest functions, deprecated in Python 3.11:

    • unittest.findTestCases()

    • unittest.makeSuite()

    • unittest.getTestCaseNames()

    Use TestLoader methods instead:

    Patch by Hugo van Kemenade.

  • gh-104804: Remove the untested and undocumented webbrowser MacOSX class, deprecated in Python 3.11. Patch by Hugo van Kemenade.

  • gh-83863: Support for using pathlib.Path objects as context managers has been removed. Before Python 3.9, exiting the context manager marked a path as “closed”, which caused some (but not all!) methods to raise when called. Since Python 3.9, using a path as a context manager does nothing.

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

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

  • gh-104783: Remove locale.resetlocale() function deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104780: Remove the 2to3 program and the lib2to3 module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the telnetlib module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the imghdr module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the cgi and cgitb modules, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the sndhdr module, deprecated in Python 3.11. Patch by Victor Stinner.

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

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

  • gh-102613: Improve performance of pathlib.Path.glob() when expanding a pattern with a non-terminal “**” component by filtering walked paths through a regular expression, rather than calling os.scandir() more than once on each directory.

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

  • gh-102676: Add fields start_offset, cache_offset, end_offset, baseopname, baseopcode, jump_target and oparg to dis.Instruction.

  • gh-103558: Fixed parent argument validation mechanism of argparse. Improved test coverage.

  • gh-103464: Provide helpful usage messages when parsing incorrect pdb commands.

  • gh-103384: Generalize the regex pattern BaseConfigurator.INDEX_PATTERN to allow spaces and non-alphanumeric characters in keys.

  • gh-103124: Added multiline statement support for pdb

  • gh-101162: Forbid using builtins.issubclass() with types.GenericAlias as the first argument.

  • gh-103200: Fix cache repopulation semantics of zipimport.invalidate_caches(). The cache is now repopulated upon retrieving files with an invalid cache, not when the cache is invalidated.

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

  • gh-77609: Add follow_symlinks argument to pathlib.Path.glob() and rglob(), defaulting to false.

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

  • gh-102120: Added a stream mode to tarfile that allows for reading archives without caching info about the inner files.

  • gh-102029: Deprecate passing any arguments to threading.RLock().

  • gh-88233: Refactored zipfile._strip_extra to use higher level abstactions for extras instead of a heavy-state loop.

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

  • gh-73435: Add support for recursive wildcards in pathlib.PurePath.match().

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

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

  • gh-80480: Emit DeprecationWarning for array’s 'u' type code, deprecated in docs since Python 3.3.

  • gh-94924: unittest.mock.create_autospec() now properly returns coroutine functions compatible with inspect.iscoroutinefunction()

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

  • gh-92871: Remove the typing.io and typing.re namespaces, deprecated since Python 3.8. All items are still available from the main typing module.

  • bpo-43633: Improve the textual representation of IPv4-mapped IPv6 addresses (RFC 4291 Sections 2.2, 2.5.5.2) in ipaddress. Patch by Oleksandr Pavliuk.

  • bpo-44850: Improve performance of operator.methodcaller() using the PEP 590 vectorcall convention. Patch by Anthony Lee and Pieter Eendebak.

  • bpo-44185: unittest.mock.mock_open() will call the close() method of the file handle mock when it is exiting from the context manager. Patch by Samet Yaslan.

  • bpo-40988: Improve performance of functools.singledispatchmethod by caching the generated dispatch wrapper. Optimization suggested by frederico. Patch by @mental32, Alex Waygood and Pieter Eendebak.

  • bpo-41768: unittest.mock speccing no longer calls class properties. Patch by Melanie Witt.

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

  • bpo-17013: Add ThreadingMock to unittest.mock that can be used to create Mock objects that can wait until they are called. Patch by Karthikeyan Singaravelan and Mario Corchero.

Documentation

Tests

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

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

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

  • gh-110388: Add tests for tty.

  • gh-81002: Add tests for termios.

  • gh-110367: regrtest: When using worker processes (-jN) with –verbose3 option, regrtest can now display the worker output even if a worker process does crash. Previously, sys.stdout and sys.stderr were replaced and so the worker output was lost on a crash. Patch by Victor Stinner.

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

  • gh-110171: libregrtest now always sets and shows random.seed, so tests are more reproducible. Use --randseed flag to pass the explicit random seed for tests.

  • gh-110152: Remove Tools/scripts/run_tests.py and make hostrunnertest. Just run ./python -m test --slow-ci, make buildbottest or make test instead. Python test runner (regrtest) now handles cross-compilation and HOSTRUNNER. It also adds options to Python such fast -u -E -W default -bb when --fast-ci or --slow-ci option is used. Patch by Victor Stinner.

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

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

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

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

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

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

  • gh-109566: regrtest: When --fast-ci or --slow-ci option is used, regrtest now replaces the current process with a new process to add -u -W default -bb -E options to Python. Patch by Victor Stinner.

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

  • gh-109739: regrtest: Fix reference leak check on Windows. Disable the load tracker on Windows in the reference leak check mode (-R option). Patch by Victor Stinner.

  • gh-109276: regrtest: When a test fails with “env changed” and the –rerun option is used, the test is now re-run in verbose mode in a fresh process. Patch by Victor Stinner.

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

  • gh-109580: Skip test_perf_profiler if Python is built with ASAN, MSAN or UBSAN sanitizer. Python does crash randomly in this test on such build. Patch by Victor Stinner.

  • gh-109566: regrtest: Add --fast-ci and --slow-ci options. --fast-ci uses a default timeout of 10 minutes and -u all,-cpu (skip slowest tests). --slow-ci uses a default timeout of 20 minues and -u all (run all tests). Patch by Victor Stinner.

  • gh-109425: libregrtest now decodes stdout of test worker processes with the “backslashreplace” error handler to log corrupted stdout, instead of failing with an error and not logging the stdout. Patch by Victor Stinner.

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

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

  • gh-109276: libregrtest now calls random.seed() before running each test file when -r/--randomize command line option is used. Moreover, it’s also called in worker processes. It should help to make tests more deterministic. Previously, it was only called once in the main process before running all test files and it was not called in worker processes. Patch by Victor Stinner.

  • gh-109276: libregrtest now uses a separated file descriptor to write test result as JSON. Previously, if a test wrote debug messages late around the JSON, the main test process failed to parse JSON. Patch by Victor Stinner.

  • gh-108996: Fix and enable test_msvcrt.

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

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

  • gh-108996: Add tests for msvcrt.

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

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

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

  • gh-91960: FreeBSD 13.2 CI coverage for pull requests is now provided by Cirrus-CI (a hosted CI service that supports Linux, macOS, Windows, and FreeBSD).

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

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

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

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

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

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

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

  • gh-108794: The doctest.DocTestRunner.run() method now counts the number of skipped tests. Add doctest.DocTestRunner.skips and doctest.TestResults.skipped attributes. Patch by Victor Stinner.

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

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

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

  • gh-107652: Set up CIFuzz to run fuzz targets in GitHub Actions. Patch by Illia Volochii.

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

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

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

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

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

  • gh-106690: Add .coveragerc to cpython repository for use with coverage package.

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

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

  • gh-81005: String tests are modified to reflect that str and unicode are merged in Python 3. Patch by Daniel Fortunov.

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

  • gh-69714: Add additional tests to calendar to achieve full test coverage.

Build

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

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

  • gh-110276: No longer ignore PROFILE_TASK failure silently: command used by Profile Guided Optimization (PGO). Patch by Victor Stinner.

  • gh-109566: Remove make testall target: use make buildbottest instead. Patch by Victor Stinner.

  • gh-109740: The experimental --disable-gil configure flag now includes “t” (for “threaded”) in extension ABI tags.

  • gh-109054: Fix building the _testcapi extension on Linux AArch64 which requires linking to libatomic when <cpython/pyatomic.h> is used: the _Py_atomic_or_uint64() function requires libatomic __atomic_fetch_or_8() on this platform. The configure script now checks if linking to libatomic is needed and generates a new LIBATOMIC variable used to build the _testcapi extension. Patch by Victor Stinner.

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

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

  • gh-108634: Python built with configure --with-trace-refs (tracing references) is now ABI compatible with Python release build and debug build. Patch by Victor Stinner.

  • gh-85283: The _stat C extension is now built with the limited C API. Patch by Victor Stinner.

  • gh-108447: Fix x86_64 GNU/Hurd build

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

  • gh-105481: Remove the make target regen-opcode-targets, merge its work into regen-opcode which repeats most of the calculation. This simplifies the code for the build and reduces code duplication.

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

  • gh-95855: Refactor platform triplet detection code and add detection for MIPS soft float and musl libc.

  • gh-106962: Detect MPI compilers in configure.

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

  • gh-105875: SQLite 3.15.2 or newer is required to build the sqlite3 extension module. Patch by Erlend Aasland.

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

  • gh-102404: Document how to perform a WASI build on Linux. Also add Tools/wasm/build_wasi.sh as a reference implementation of the docs.

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

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

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

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

Windows

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

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

  • gh-82367: os.path.realpath() now resolves MS-DOS style file names even if the file is not accessible. Patch by Moonsik Park.

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

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

  • gh-83180: Changes the Python Launcher for Windows to prefer an active virtual environment when the launched script has a shebang line using a Unix-like virtual command, even if the command requests a specific version of Python.

  • gh-106844: Fix integer overflow and truncating by the null character in _winapi.LCMapStringEx() which affects ntpath.normcase().

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

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

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

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

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

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

macOS

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

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

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

IDLE

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

Tools/Demos

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

  • gh-108494: Argument Clinic now has a partial support of the Limited API: see documentation in the Python Developer’s Guide Patch by Victor Stinner.

  • gh-107704: It is now possible to deprecate passing keyword arguments for keyword-or-positional parameters with Argument Clinic, using the new / [from X.Y] syntax. (To be read as “positional-only from Python version X.Y”.) See documentation in the Python Developer’s Guide for more information.

  • gh-107880: Argument Clinic can now clone __init__() and __new__() methods.

  • gh-104683: Add --exclude option to Argument Clinic CLI.

  • gh-95065: Argument Clinic now supports overriding automatically generated signature by using directive @text_signature. See documentation in the Python Developer’s Guide

  • gh-107609: Fix duplicate module check in Argument Clinic. Previously, a duplicate definition would incorrectly be silently accepted. Patch by Erlend E. Aasland.

  • gh-107467: The Argument Clinic command-line tool now prints to stderr instead of stdout on failure.

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

  • gh-106706: Change bytecode syntax for families to remove redundant name matching pseudo syntax.

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

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

  • gh-95065: It is now possible to deprecate passing parameters positionally with Argument Clinic, using the new * [from X.Y] syntax. (To be read as “keyword-only from Python version X.Y”.) See documentation in the Python Developer’s Guide for more information. Patch by Erlend E. Aasland with help from Alex Waygood, Nikita Sobolev, and Serhiy Storchaka.

C API

Python 3.12.0 beta 1

Release date: 2023-05-22

Security

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

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

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

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

Core and Builtins

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Library

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • gh-103977: Improve import time of platform module.

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

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

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

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

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

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

  • gh-103583: Isolate _multibytecodec and codecs extension modules. Patches by Erlend E. Aasland.

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

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

  • gh-99944: Make dis display the value of oparg of KW_NAMES.

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

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

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

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

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

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

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

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

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

  • gh-103693: Add convenience variable feature to pdb

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • gh-102778: Support sys.last_exc in idlelib.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • gh-91896: Deprecate collections.abc.ByteString

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Documentation

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

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

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

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

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

Tests

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

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

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

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

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

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

Build

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

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

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

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

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

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

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

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

    • loongarch64-linux-gnusf

    • loongarch64-linux-gnuf32

    • loongarch64-linux-gnu

    Patch by Zhang Na.

Windows

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

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

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

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

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

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

macOS

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

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

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

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

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

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

IDLE

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

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

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

Tools/Demos

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

C API

Python 3.12.0 alpha 7

Release date: 2023-04-04

Core and Builtins

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

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

  • gh-102859: Removed JUMP_IF_FALSE_OR_POP and JUMP_IF_TRUE_OR_POP instructions.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Library

Documentation

Tests

  • gh-102980: Improve test coverage on pdb.

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

  • gh-101377: Improved test_locale_calendar_formatweekday of calendar.

Build

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

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

Windows

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

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

Tools/Demos

C API

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

Python 3.12.0 alpha 6

Release date: 2023-03-07

Security

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

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

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

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

Core and Builtins

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

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

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

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

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

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

  • gh-102027: Use GetCurrentProcessId on Windows when getpid is unavailable. Patch by Max Bachmann.

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

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

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

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

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

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

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

  • gh-84783: Make the slice object hashable. Patch by Will Bradshaw and Furkan Onder.

  • gh-87849: Change the SEND instruction to leave the receiver on the stack. This allows the specialized form of SEND to skip the chain of C calls and jump directly to the RESUME in the generator or coroutine.

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

  • gh-101430: Update tracemalloc to handle presize of object properly. Patch by Donghee Na.

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

  • gh-101632: Adds a new RETURN_CONST instruction.

  • gh-100719: Remove gi_code field from generator (and coroutine and async generator) objects as it is redundant. The frame already includes a reference to the code object.

  • gh-98627: When an interpreter is configured to check (and only then), importing an extension module will now fail when the extension does not support multiple interpreters (i.e. doesn’t implement PEP 489 multi-phase init). This does not apply to the main interpreter, nor to subinterpreters created with Py_NewInterpreter().

Library

Documentation

Tests

  • gh-102019: Fix deadlock on shutdown if test_current_{exception,frames} fails. Patch by Jacob Bower.

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

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

Build

  • gh-99942: On Android, in a static build, python-config in embed mode no longer incorrectly reports a library to link to.

  • gh-99942: On Android, python.pc now correctly reports the library to link to, the same as python-config.sh.

  • gh-100221: Fix creating install directories in make sharedinstall if they exist outside DESTDIR already.

  • gh-96821: Explicitly mark C extension modules that need defined signed integer overflow, and add a configure option --with-strict-overflow. Patch by Matthias Görgens and Shantanu Jain.

Windows

  • gh-102344: Implement winreg.QueryValue using QueryValueEx and winreg.SetValue using SetValueEx. Patch by Max Bachmann.

  • gh-101881: Handle read and write operations on non-blocking pipes properly on Windows.

  • gh-101881: Add support for the os.get_blocking() and os.set_blocking() functions on Windows.

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

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

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

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

  • gh-101196: The functions os.path.isdir, os.path.isfile, os.path.islink and os.path.exists are now 13% to 28% faster on Windows, by making fewer Win32 API calls.

macOS

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

C API

  • gh-101907: Removes use of non-standard C++ extension in public header files.

  • gh-99293: Document that the Py_TPFLAGS_VALID_VERSION_TAG is an internal feature, should not be used, and will be removed.

  • gh-101578: Add PyErr_GetRaisedException() and PyErr_SetRaisedException() for saving and restoring the current exception. These functions return and accept a single exception object, rather than the triple arguments of the now-deprecated PyErr_Fetch() and PyErr_Restore(). This is less error prone and a bit more efficient.

    Add PyException_GetArgs() and PyException_SetArgs() as convenience functions for retrieving and modifying the args passed to the exception’s constructor.

  • gh-91744: Introduced the Unstable C API tier, marking APi that is allowed to change in minor releases without a deprecation period. See PEP 689 for details.

Python 3.12.0 alpha 5

Release date: 2023-02-07

Security

  • gh-99108: Replace the builtin hashlib implementations of SHA2-224 and SHA2-256 originally from LibTomCrypt with formally verified, side-channel resistant code from the HACL* project. The builtins remain a fallback only used when OpenSSL does not provide them.

Core and Builtins

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

  • gh-59956: The GILState API is now partially compatible with subinterpreters. Previously, PyThreadState_GET() and PyGILState_GetThisThreadState() would get out of sync, causing inconsistent behavior and crashes.

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

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

  • gh-101266: Fix sys.getsizeof() reporting for int subclasses.

  • gh-101291: Refactor the PyLongObject struct into a normal Python object header and a PyLongValue struct.

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

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

  • gh-100762: Record the (virtual) exception block depth in the oparg of YIELD_VALUE. Use this to avoid the expensive throw() when closing generators (and coroutines) that can be closed trivially.

  • gh-100982: Adds a new COMPARE_AND_BRANCH instruction. This is a bit more efficient when performing a comparison immediately followed by a branch, and restores the design intent of PEP 659 that specializations are local to a single instruction.

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

  • gh-100923: Remove the mask cache entry for the COMPARE_OP instruction and embed the mask into the oparg.

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

  • gh-91351: Fix a case where re-entrant imports could corrupt the import deadlock detection code and cause a KeyError to be raised out of importlib/_bootstrap. In addition to the straightforward cases, this could also happen when garbage collection leads to a warning being emitted – as happens when it collects an open socket or file)

  • gh-100726: Optimize construction of range object for medium size integers.

  • gh-100712: Added option to build cpython with specialization disabled, by setting ENABLE_SPECIALIZATION=False in opcode, followed by make regen-all.

  • bpo-32780: Inter-field padding is now inserted into the PEP3118 format strings obtained from ctypes.Structure objects, reflecting their true representation in memory.

Library

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

  • gh-101570: Upgrade pip wheel bundled with ensurepip (pip 23.0)

  • gh-101323: Fix a bug where errors where not thrown by zlib._ZlibDecompressor if encountered during decompressing.

  • gh-101317: Add ssl_shutdown_timeout parameter for asyncio.StreamWriter.start_tls().

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

  • gh-92123: Adapt the _elementtree extension module to multi-phase init (PEP 489). Patches by Erlend E. Aasland.

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

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

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

  • gh-94518: Group-related variables of _posixsubprocess module are renamed to stress that supplimentary group affinity is added to a fork, not replace the inherited ones. Patch by Oleg Iarygin.

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

  • gh-101000: Add os.path.splitroot(), which splits a path into a 3-item tuple (drive, root, tail). This new function is used by pathlib to improve the performance of path construction by up to a third.

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

  • gh-39615: warnings.warn() now has the ability to skip stack frames based on code filename prefix rather than only a numeric stacklevel via the new skip_file_prefixes keyword argument.

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

  • gh-100160: Emit a deprecation warning in asyncio.DefaultEventLoopPolicy.get_event_loop() if there is no current event loop set and it decides to create one.

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

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

  • gh-67790: Add float-style formatting support for fractions.Fraction instances.

  • gh-99266: Preserve more detailed error messages in ctypes.

  • gh-86682: Ensure runtime-created collections have the correct module name using the newly added (internal) sys._getframemodulename().

  • gh-88597: uuid now has a command line interface. Try python -m uuid -h.

  • gh-60580: ctypes.wintypes.BYTE definition changed from c_byte to c_ubyte to match Windows SDK. Patch by Anatoly Techtonik and Oleg Iarygin.

  • gh-94518: _posixsubprocess now initializes all UID and GID variables using a reserved -1 value instead of a separate flag. Patch by Oleg Iarygin.

  • bpo-38941: The xml.etree.ElementTree module now emits DeprecationWarning when testing the truth value of an xml.etree.ElementTree.Element. Before, the Python implementation emitted FutureWarning, and the C implementation emitted nothing.

  • bpo-40077: Convert elementtree types to heap types. Patch by Erlend E. Aasland.

  • bpo-29847: Fix a bug where pathlib.Path accepted and ignored keyword arguments. Patch provided by Yurii Karabas.

  • gh-77772: ctypes.CDLL, ctypes.OleDLL, ctypes.WinDLL, and ctypes.PyDLL now accept path-like objects as their name argument. Patch by Robert Hoelzl.

Documentation

  • gh-88324: Reword subprocess to emphasize default behavior of stdin, stdout, and stderr arguments. Remove inaccurate statement about child file handle inheritance.

Tests

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

Build

  • gh-101282: Update BOLT configration not to use depreacted usage of --split functions. Patch by Donghee Na.

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

  • gh-77532: Minor fixes to allow building with PlatformToolset=ClangCL on Windows.

  • gh-101152: In accordance with PEP 699, the ma_version_tag field in PyDictObject is deprecated for extension modules. Accessing this field will generate a compiler warning at compile time. This field will be removed in Python 3.14.

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

  • gh-101060: Conditionally add -fno-reorder-blocks-and-partition in configure. Effectively fixes --enable-bolt when using Clang, as this appears to be a GCC-only flag.

  • gh-98705: __bool__ is defined in AIX system header files which breaks the build in AIX, so undefine it.

  • gh-98636: Fix a regression in detecting gdbm_compat library for the _gdbm module build.

  • gh-96305: _aix_support now uses a simple code to get platform details rather than the now non-existent _bootsubprocess during bootstrap.

Windows

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

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

  • gh-99834: Updates bundled copy of Tcl/Tk to 8.6.13.0

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

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

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

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

Python 3.12.0 alpha 4

Release date: 2023-01-10

Core and Builtins

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

  • gh-99005: Remove UNARY_POSITIVE, ASYNC_GEN_WRAP and LIST_TO_TUPLE, replacing them with intrinsics.

  • gh-99005: Add new CALL_INTRINSIC_1 instruction. Remove IMPORT_STAR, PRINT_EXPR and STOPITERATION_ERROR, replacing them with the CALL_INTRINSIC_1 instruction.

  • gh-100288: Remove the LOAD_ATTR_METHOD_WITH_DICT specialized instruction. Stats show it is not useful.

  • gh-100720: Added _PyFrame_NumSlotsForCodeObject, which returns the number of slots needed in a frame for a given code object.

  • gh-100719: Removed the co_nplaincellvars field from the code object, as it is redundant.

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

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

  • gh-100126: Fix an issue where “incomplete” frames could be briefly visible to C code while other frames are being torn down, possibly resulting in corruption or hard crashes of the interpreter while running finalizers.

  • gh-87447: Fix SyntaxError on comprehension rebind checking with names that are not actually redefined.

    Now reassigning b in [(b := 1) for a, b.prop in some_iter] is allowed. Reassigning a is still disallowed as per PEP 572.

  • gh-100268: Add int.is_integer() to improve duck type compatibility between int and float.

  • gh-100425: Improve the accuracy of sum() with compensated summation.

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

  • gh-100357: Convert vars, dir, next, getattr, and iter to argument clinic.

  • gh-100117: Improve the output of codeobject.co_lines() by emitting only one entry for each line range.

  • gh-90043: Handle NaNs when specializing COMPARE_OP for float values.

  • gh-100222: Redefine the _Py_CODEUNIT typedef as a union to describe its layout to the C compiler, avoiding type punning and improving clarity.

  • gh-99955: Internal compiler functions (in compile.c) now consistently return -1 on error and 0 on success.

  • gh-100188: The BINARY_SUBSCR_LIST_INT and BINARY_SUBSCR_TUPLE_INT instructions are no longer used for negative integers because those instructions always miss when encountering negative integers.

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

  • gh-94155: Improved the hashing algorithm for code objects, mitigating some hash collisions.

  • gh-99540: None now hashes to a constant value. This is not a requirements change.

  • gh-100143: When built with --enable-pystats, stats collection is now off by default. To enable it early at startup, pass the -Xpystats flag. Stats are now always dumped, even if switched off.

  • gh-100146: Improve BUILD_LIST opcode so that it works similarly to the BUILD_TUPLE opcode, by stealing references from the stack rather than repeatedly using stack operations to set list elements. Implementation details are in a new private API _PyList_FromArraySteal().

  • gh-100110: Specialize FOR_ITER for tuples.

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

  • gh-92216: Improve the performance of hasattr() for type objects with a missing attribute.

  • gh-99582: Freeze zipimport module into _bootstrap_python.

  • gh-99554: Pack debugging location tables more efficiently during bytecode compilation.

  • gh-98522: Add an internal version number to code objects, to give better versioning of inner functions and comprehensions, and thus better specialization of those functions. This change is invisible to both Python and C extensions.

  • gh-94603: Improve performance of list.pop for small lists.

  • gh-89051: Add ssl.OP_LEGACY_SERVER_CONNECT

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

Library

Documentation

Tests

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

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

  • gh-93018: Make two tests forgiving towards host system libexpat with backported security fixes applied.

Build

  • gh-100540: Removed the --with-system-ffi configure option; libffi must now always be supplied by the system on all non-Windows platforms. The option has had no effect on non-Darwin platforms for several releases, and in 3.11 only had the non-obvious effect of invoking pkg-config to find libffi and never setting -DUSING_APPLE_OS_LIBFFI. Now on Darwin platforms configure will first check for the OS libffi and then fall back to the same processing as other platforms if it is not found.

  • gh-88267: Avoid exporting Python symbols in linked Windows applications when the core is built as static.

  • bpo-41916: Allow override of ac_cv_cxx_thread so that cross compiled python can set -pthread for CXX.

Windows

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

  • gh-99191: Use _MSVC_LANG >= 202002L instead of less-precise _MSC_VER >=1929 to more accurately test for C++20 support in PC/_wmimodule.cpp.

  • gh-79218: Define MS_WIN64 for Mingw-w64 64bit, fix cython compilation failure.

  • gh-99941: Ensure that asyncio.Protocol.data_received() receives an immutable bytes object (as documented), instead of bytearray.

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

  • bpo-34816: hasattr(ctypes.windll, 'nonexistant') now returns False instead of raising OSError.

macOS

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

  • gh-100540: Removed obsolete dlfcn.h shim from the _ctypes extension module, which has not been necessary since Mac OS X 10.2.

Tools/Demos

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

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

C API

  • gh-99947: Raising SystemError on import will now have its cause be set to the original unexpected exception.

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

  • gh-98724: The Py_CLEAR, Py_SETREF and Py_XSETREF macros now only evaluate their arguments once. If an argument has side effects, these side effects are no longer duplicated. Patch by Victor Stinner.

Python 3.12.0 alpha 3

Release date: 2022-12-06

Security

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

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

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

Core and Builtins

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

  • gh-91054: Add PyCode_AddWatcher() and PyCode_ClearWatcher() APIs to register callbacks to receive notification on creation and destruction of code objects.

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

  • gh-99708: Fix bug where compiler crashes on an if expression with an empty body block.

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

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

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

  • gh-99547: Add a function to os.path to check if a path is a junction: isjunction. Add similar functionality to pathlib.Path as is_junction.

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

  • gh-99377: Add audit events for thread creation and clear operations.

  • gh-98686: Remove the BINARY_OP_GENERIC and COMPARE_OP_GENERIC “specializations”.

  • gh-99298: Remove the remaining error paths for attribute specializations, and refuse to specialize attribute accesses on types that haven’t had PyType_Ready() called on them yet.

  • gh-99127: Allow some features of syslog to the main interpreter only. Patch by Donghee Na.

  • gh-91053: Optimizing interpreters and JIT compilers may need to invalidate internal metadata when functions are modified. This change adds the ability to provide a callback that will be invoked each time a function is created, modified, or destroyed.

  • gh-90994: Improve error messages when there’s a syntax error with call arguments. The following three cases are covered: - No value is assigned to a named argument, eg foo(a=). - A value is assigned to a star argument, eg foo(*args=[0]). - A value is assigned to a double-star keyword argument, eg foo(**kwarg={'a': 0}).

  • bpo-45026: Optimize the range object iterator. It is now smaller, faster iteration of ranges containing large numbers. Smaller pickles, faster unpickling.

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

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

Library

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

  • gh-99957: Add frozen_default parameter to typing.dataclass_transform().

  • gh-79033: Fix asyncio.Server.wait_closed() to actually do what the docs promise – wait for all existing connections to complete, after closing the server.

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

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

  • gh-99508: Fix TypeError in Lib/importlib/_bootstrap_external.py while calling _imp.source_hash().

  • gh-66285: Fix asyncio to not share event loop and signal wakeupfd in forked processes. Patch by Kumar Aditya.

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

  • gh-92647: Use final status of an enum to determine lookup or creation branch of functional API.

  • gh-99388: Add loop_factory parameter to asyncio.run() to allow specifying a custom event loop factory. Patch by Kumar Aditya.

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

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

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

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

  • gh-99284: Remove _use_broken_old_ctypes_structure_semantics_ old untested and undocumented hack from ctypes.

  • gh-99201: Fix IndexError when initializing the config variables on Windows if HAVE_DYNAMIC_LOADING is not set.

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

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

  • gh-99029: pathlib.PurePath.relative_to() now treats naked Windows drive paths as relative. This brings its behaviour in line with other parts of pathlib.

  • gh-98253: The implementation of the typing module is now more resilient to reference leaks in binary extension modules.

    Previously, a reference leak in a typed C API-based extension module could leak internals of the typing module, which could in turn introduce leaks in essentially any other package with typed function signatures. Although the typing package is not the original source of the problem, such non-local dependences exacerbate debugging of large-scale projects, and the implementation was therefore changed to reduce harm by providing better isolation.

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

  • gh-93453: asyncio.get_event_loop() and many other asyncio functions like asyncio.ensure_future(), asyncio.shield() or asyncio.gather(), and also the get_event_loop() method of asyncio.BaseDefaultEventLoopPolicy now raise a RuntimeError if called when there is no running event loop and the current event loop was not set. Previously they implicitly created and set a new current event loop. DeprecationWarning is no longer emitted if there is no running event loop but the current event loop was set.

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

  • gh-98248: Provide informative error messages in struct.pack() when its integral arguments are not in range.

  • gh-98108: zipfile.Path is now pickleable if its initialization parameters were pickleable (e.g. for file system paths).

  • gh-98098: Created packages from zipfile and test_zipfile modules, separating zipfile.Path functionality.

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

  • gh-96828: Add an OP_ENABLE_KTLS option for enabling the use of the kernel TLS (kTLS). Patch by Illia Volochii.

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

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

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

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

  • bpo-41260: Rename the fmt parameter of the pure Python implementation of datetime.date.strftime() to format.

  • bpo-15999: All built-in functions now accept arguments of any type instead of just bool and int for boolean parameters.

Documentation

  • gh-99931: Use sphinxext-opengraph to generate OpenGraph metadata.

  • gh-89682: Reworded docstring of the default __contains__ to clarify that it returns a bool.

  • gh-88330: Improved the description of what a resource is in importlib.resources docs.

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

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

Tests

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

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

  • gh-99741: We’ve implemented multi-phase init (PEP 489/630/687) for the internal (for testing) _xxsubinterpreters module.

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

  • gh-99593: Cover the Unicode C API with tests.

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

Build

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

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

  • gh-99289: Add a COMPILEALL_OPTS variable in Makefile to override compileall options (default: -j0) in make install. Also merged the compileall commands into a single command building .pyc files for the all optimization levels (0, 1, 2) at once. Patch by Victor Stinner.

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

  • gh-88226: Always define TARGET_* labels in Python/ceval.c, even if USE_COMPUTED_GOTOS is disabled. This allows breakpoints to be set at those labels in (for instance) gdb.

Windows

macOS

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

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

Tools/Demos

  • gh-64490: Argument Clinic varargs bugfixes

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

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

    • Fix miscalculation of noptargs in generated code.

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

C API

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

  • gh-99612: Fix PyUnicode_DecodeUTF8Stateful() for ASCII-only data: *consumed was not set.

  • gh-47146: The structmember.h header is deprecated. Its non-deprecated contents are now available just by including Python.h, with a Py_ prefix added if it was missing. (Deprecated contents are T_OBJECT, T_NONE, and no-op flags.) Patch by Petr Viktorin, based on earlier work by Alexander Belopolsky and Matthias Braun.

Python 3.12.0 alpha 2

Release date: 2022-11-14

Security

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

    Individual labels within an IDNA encoded DNS name will now raise an error early during IDNA decoding if they are longer than 1024 unicode characters given that each decoded DNS label must be 63 or fewer characters and the entire decoded DNS name is limited to 255. Only an application presenting a hostname or label consisting primarily of RFC 3454 section 3.1 “Nothing” characters to be removed would run into of this new limit. See also RFC 5894 section 6 and RFC 3491.

  • gh-98739: Update bundled libexpat to 2.5.0

Core and Builtins

  • gh-81057: The docs clearly say that PyImport_Inittab, PyImport_AppendInittab(), and PyImport_ExtendInittab() should not be used after Py_Initialize() has been called. We now enforce this for the two functions. Additionally, the runtime now uses an internal copy of PyImport_Inittab, to guard against modification.

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

  • gh-99254: The compiler now removes all unused constants from code objects (except the first one, which may be a docstring).

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

  • gh-81057: The 18 global C variables holding the state of the allocators have been moved to _PyRuntimeState. This is a strictly internal change with no change in behavior.

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

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

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

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

  • gh-98686: Merge the adaptive opcode logic into each instruction’s unquickened variant, and merge the logic in EXTENDED_ARG_QUICK into EXTENDED_ARG. With these changes, the quickening that happens at code object creation is now only responsible for initializing warmup counters and inserting superinstructions.

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

  • gh-99139: Improve the error suggestion for NameError exceptions for instances. Now if a NameError is raised in a method and the instance has an attribute that’s exactly equal to the name in the exception, the suggestion will include self.<NAME> instead of the closest match in the method scope. Patch by Pablo Galindo

  • gh-98401: Octal escapes with value larger than 0o377 (ex: "\477"), deprecated in Python 3.11, now produce a SyntaxWarning, instead of DeprecationWarning. In a future Python version they will be eventually a SyntaxError. Patch by Victor Stinner.

  • gh-98401: A backslash-character pair that is not a valid escape sequence now generates a SyntaxWarning, instead of DeprecationWarning. For example, re.compile("\d+\.\d+") now emits a SyntaxWarning ("\d" is an invalid escape sequence), use raw strings for regular expression: re.compile(r"\d+\.\d+"). In a future Python version, SyntaxError will eventually be raised, instead of SyntaxWarning. Patch by Victor Stinner.

  • gh-96793: Handle StopIteration and StopAsyncIteration raised in generator or coroutines in the bytecode, rather than in wrapping C code.

  • gh-98931: Improve the SyntaxError error message when the user types import x from y instead of from y import x. Patch by Pablo Galindo

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

  • gh-98925: Lower the recursion depth for marshal on WASI to support (in-development) wasmtime 2.0.

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

  • gh-98811: Use complete source locations to simplify detection of __future__ imports which are not at the beginning of the file. Also corrects the offset in the exception raised in one case, which was off by one and impeded highlighting.

  • gh-96793: Add specialization of FOR_ITER for generators. Saves multiple layers of dispatch and checking to get from the FOR_ITER instruction in the caller to the RESUME in the generator.

  • gh-98762: Fix source locations of match sub-patterns.

  • gh-98586: Added the methods PyObject_Vectorcall() and PyObject_VectorcallMethod() to the Limited API along with the auxiliary macro constant PY_VECTORCALL_ARGUMENTS_OFFSET.

    The availability of these functions enables more efficient PEP 590 vector calls from binary extension modules that avoid argument boxing/unboxing overheads.

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

  • gh-93143: Rather than changing co_code, the interpreter will now display a RuntimeWarning and assign None to any fast locals that are left unbound after jumps or del statements executed while tracing.

  • gh-96421: When calling into Python code from C code, through PyEval_EvalFrameEx() or a related C-API function, a shim frame in inserted into the call stack. This occurs in the _PyEval_EvalFrameDefault() function. The extra frame should be invisible to all Python and most C extensions, but out-of-process profilers and debuggers need to be aware of it. These shim frames can be detected by checking frame->owner == FRAME_OWNED_BY_CSTACK.

    Extensions implementing their own interpreters using PEP 523 need to be aware of this shim frame and the changes to the semantics of RETURN_VALUE, YIELD_VALUE, and RETURN_GENERATOR, which now clear the frame.

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

  • gh-98686: Quicken all code objects, and specialize adaptive bytecode instructions more aggressively.

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

  • gh-91058: ImportError raised from failed from <module> import <name> now include suggestions for the value of <name> based on the available names in <module>. Patch by Pablo Galindo

  • gh-96793: The FOR_ITER now leaves the iterator on the stack on termination of the loop. This is to assist specialization of loops for generators.

  • gh-90716: Add _pylong.py module. It includes asymptotically faster algorithms that can be used for operations on integers with many digits. It is used by longobject.c to speed up some operations.

  • gh-95389: Expose ETH_P_ALL and some of the ETHERTYPE_* constants in socket. Patch by Noam Cohen.

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

Library

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

  • gh-94597: Deprecate asyncio.AbstractChildWatcher to be removed in Python 3.14. Patch by Kumar Aditya.

  • gh-99305: Improve performance of secrets.token_hex().

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

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

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

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

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

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

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

  • gh-92584: Remove the distutils package. It was deprecated in Python 3.10 by PEP 632 “Deprecate distutils module”. For projects still using distutils and cannot be updated to something else, the setuptools project can be installed: it still provides distutils. Patch by Victor Stinner.

  • gh-98999: Now _pyio is consistent with _io in raising ValueError when executing methods over closed buffers.

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

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

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

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

  • gh-98878: Use the frame bound builtins when offering a name suggestion in traceback to prevent crashing when __builtins__ is not a dict.

  • gh-98139: In importlib._bootstrap, enhance namespace package repr to <module 'x' (namespace) from ['path']>.

  • gh-90352: Fix _SelectorDatagramTransport to inherit from DatagramTransport in asyncio. Patch by Kumar Aditya.

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

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

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

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

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

  • gh-98658: The array.array class now supports subscripting, making it a generic type.

  • gh-98284: Improved TypeError message for undefined abstract methods of a abc.ABC instance. The names of the missing methods are surrounded by single-quotes to highlight them.

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

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

  • gh-72719: Remove modules asyncore and asynchat, which were deprecated by PEP 594.

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

  • gh-94172: ftplib: Remove the FTP_TLS.ssl_version class attribute: use the context parameter instead. Patch by Victor Stinner

  • gh-94172: Remove the keyfile and certfile parameters from the ftplib, imaplib, poplib and smtplib modules, and the key_file, cert_file and check_hostname parameters from the http.client module, all deprecated since Python 3.6. Use the context parameter (ssl_context in imaplib) instead. Patch by Victor Stinner.

  • gh-83638: Add the autocommit attribute to sqlite3.Connection and the autocommit parameter to sqlite3.connect() to control PEP 249-compliant transaction handling. Patch by Erlend E. Aasland.

  • gh-92452: Fixed a race condition that could cause sysconfig.get_config_var() to incorrectly return None in multi-threaded programs.

  • gh-91803: Fix an error when using a method of objects mocked with unittest.mock.create_autospec() after it was sealed with unittest.mock.seal() function.

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

  • bpo-40358: Add walk_up argument in pathlib.PurePath.relative_to().

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

Documentation

  • gh-98832: Changes wording of docstring for pathlib.Path.iterdir().

  • gh-97966: Update uname docs to clarify the special nature of the platform attribute and to indicate when it became late-bound.

Tests

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

  • gh-98713: Fix a bug in the typing tests where a test relying on CPython-speci