3.12.0a6.rst

Replace builtin hashlib implementations of MD5 and SHA1 with verified ones from the HACL* project.

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.

Replace the builtin :mod:`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.

:class:`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.

Fix regression in semantics of normalisation in PyErr_SetObject.

Do not memoize incorrectly automatically generated loop rules in the parser. Patch by Pablo Galindo.

Fix a bug that caused a crash when deallocating deeply nested filter objects. Patch by Marta Gómez Macías.

Cleanup Windows 7 specific special handling. Patch by Max Bachmann.

Fixed a segfault occurring when the interpreter calls a __bool__ method that raises.

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

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

Fix error handling bugs in interpreter's exception printing code, which could cause a crash on infinite recursion.

Restrict the scope of the :opcode:`FOR_ITER_RANGE` instruction to the scope of the original :opcode:`FOR_ITER` instruction, to allow instrumentation.

Fix possible segfault in positional_only_passed_as_keyword function, when new list created.

Fix possible segfault in BUILD_SET opcode, when new set created.

:mod:`socket.getaddrinfo` no longer raises :class:`OverflowError` for :class:`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 :class:`socket.gaierror` SAI_SERVICE may occur instead, or no error at all as not all platform C libraries generate an error.

Add :opcode:`CALL_INTRINSIC_2` and use it instead of :opcode:`!PREP_RERAISE_STAR`.

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

Make the slice object hashable. Patch by Will Bradshaw and Furkan Onder.

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.

Fix SystemError / segmentation fault in iter __reduce__ when internal access of builtins.__dict__ keys mutates the iter object.

Update :mod:`tracemalloc` to handle presize of object properly. Patch by Donghee Na.

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.

Adds a new :opcode:`RETURN_CONST` instruction.

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.

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().

Micro-optimise hashing of :class:`inspect.Parameter`, reducing the time it takes to hash an instance by around 40%.

Fix a bug where parentheses in the metavar argument to :meth:`argparse.ArgumentParser.add_argument` were dropped. Patch by Yeojin Kim.

:meth:`platform.platform` now has boolean default arguments.

Add :const:`mmap.MAP_ALIGNED_SUPER` FreeBSD and :const:`mmap.MAP_CONCEAL` OpenBSD constants to :mod:`mmap`. Patch by Yeojin Kim.

Fix :func:`os.dup2` error message for negative fds.

For the binary mode, :func:`fileinput.hookcompressed` doesn't set the encoding value even if the value is None. Patch by Gihwan Kim.

The default value of fp becomes :class:`io.BytesIO` if :exc:`~urllib.error.HTTPError` is initialized without a designated fp parameter. Patch by Long Vo.

In zipfile, sync Path with zipp 3.14, including fix for extractall on the underlying zipfile after being wrapped in Path.

Apply changes from importlib_resources 5.12, including fix for MultiplexedPath to support directories in multiple namespaces (python/importlib_resources#265).

Upgrade pip wheel bundled with ensurepip (pip 23.0.1)

The built-in extension modules for :mod:`hashlib` SHA2 algorithms, used when OpenSSL does not provide them, now live in a single internal _sha2 module instead of separate _sha256 and _sha512 modules.

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

Remove locking behavior from :func:`functools.cached_property`.

Fix potential undefined behaviour in corner cases of floating-point-to-time conversions.

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

Optimize :class:`fractions.Fraction` for small components. The private argument _normalize of the :class:`fractions.Fraction` constructor has been removed.

In :meth:`sqlite3.Cursor.execute`, :exc:`DeprecationWarning` is now emitted when :ref:`named placeholders <sqlite3-placeholders>` are used together with parameters supplied as a :term:`sequence` instead of as a :class:`dict`. Starting from Python 3.14, using named placeholders with parameters supplied as a sequence will raise a :exc:`~sqlite3.ProgrammingError`. Patch by Erlend E. Aasland.

Change repr of :class:`collections.OrderedDict` to use regular dictionary formatting instead of pairs of keys and values.

Speed up :class:`pathlib.PurePath` construction by handling arguments more uniformly. When a :class:`pathlib.Path` argument is supplied, we use its string representation rather than joining its parts with :func:`os.path.join`.

Speed up :class:`pathlib.PurePath` construction by calling :func:`os.path.join` only when two or more arguments are given.

Speed up :class:`pathlib.Path` construction by running the path flavour compatibility check only when pathlib is imported.

Refactored the implementation of :func:`pty.fork` to use :func:`os.login_tty`.

A :exc:`DeprecationWarning` is now raised by pty.master_open() and pty.slave_open(). They were undocumented and deprecated long long ago in the docstring in favor of :func:`pty.openpty`.

Add a new decorator :func:`typing.override`. See PEP 698 for details. Patch by Steven Troxler.

Set exit code when :mod:`tabnanny` CLI exits on error.

Fix anchor matching in :meth:`pathlib.PureWindowsPath.match`. Path and pattern anchors are now matched with :mod:`fnmatch`, just like other path parts. This allows patterns such as "*:/Users/*" to be matched.

Remove global state from :mod:`itertools` module (PEP 687). Patches by Erlend E. Aasland.

Fix handling of drive-relative paths (like 'C:' and 'C:foo') in :meth:`pathlib.Path.absolute`. This method now uses the OS API to retrieve the correct current working directory for the drive.

Apply PEP 687 to :mod:`zoneinfo`. Patch by Erlend E. Aasland.

:func:`asyncio.wait_for` now uses :func:`asyncio.timeout` as its underlying implementation. Patch by Kumar Aditya.

Correctly preserve "extra" fields in zipfile regardless of their ordering relative to a zip64 "extra."

Fix segfaults when creating :class:`lzma.LZMADecompressor` and :class:`bz2.BZ2Decompressor` objects without calling __init__(), and fix leakage of locks and internal buffers when calling the __init__() methods of :class:`lzma.LZMADecompressor`, :class:`lzma.LZMACompressor`, :class:`bz2.BZ2Compressor`, and :class:`bz2.BZ2Decompressor` objects multiple times.

Update :mod:`cmath` documentation to clarify behaviour on branch cuts.

Fix :meth:`asyncio.Task.print_stack` description for file=None. Patch by Oleg Iarygin.

Fix deadlock on shutdown if test_current_{exception,frames} fails. Patch by Jacob Bower.

Utilize new "winsize" functions from termios in pty tests.

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.

On Android, in a static build, python-config in embed mode no longer incorrectly reports a library to link to.

On Android, python.pc now correctly reports the library to link to, the same as python-config.sh.

Fix creating install directories in make sharedinstall if they exist outside DESTDIR already.

Explicitly mark C extension modules that need defined signed integer overflow, and add a configure option :option:`--with-strict-overflow`. Patch by Matthias Görgens and Shantanu Jain.

Implement winreg.QueryValue using QueryValueEx and winreg.SetValue using SetValueEx. Patch by Max Bachmann.

Handle read and write operations on non-blocking pipes properly on Windows.

Add support for the os.get_blocking() and os.set_blocking() functions on Windows.

Ensures installer will correctly upgrade existing py.exe launcher installs.

Updates copy of libffi bundled with Windows installs to 3.4.4.

Update Windows installer to SQLite 3.40.1.

Correctly handle extensions built against debug binaries that reference python3_d.dll.

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.

Update macOS installer to SQLite 3.40.1.

Removes use of non-standard C++ extension in public header files.

Document that the Py_TPFLAGS_VALID_VERSION_TAG is an internal feature, should not be used, and will be removed.

Add :c:func:`PyErr_GetRaisedException` and :c:func:`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 :c:func:`PyErr_Fetch` and :c:func:`PyErr_Restore`. This is less error prone and a bit more efficient.

Add :c:func:`PyException_GetArgs` and :c:func:`PyException_SetArgs` as convenience functions for retrieving and modifying the :attr:`~BaseException.args` passed to the exception's constructor.

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.