3.11.0a7.rst

Raise :exc:`IndentationError` instead of :exc:`SyntaxError` for a bare except with no following indent. Improve :exc:`SyntaxError` locations for an un-parenthesized generator used as arguments. Patch by Matthieu Dartiailh.

Replace :opcode:`JUMP_IF_NOT_EG_MATCH` by :opcode:`CHECK_EG_MATCH` + jump.

Emscripten builds cannot handle signals in the usual way due to platform limitations. Python can now handle signals. To use, set Module.Py_EmscriptenSignalBuffer to be a single byte SharedArrayBuffer and set Py_EMSCRIPTEN_SIGNAL_HANDLING to 1. Writing a number into the SharedArrayBuffer will cause the corresponding signal to be raised into the Python thread.

Replace :opcode:`JUMP_IF_NOT_EXC_MATCH` by :opcode:`CHECK_EXC_MATCH` + jump.

Replace the absolute jump opcode :opcode:`JUMP_NO_INTERRUPT` by the relative :opcode:`JUMP_BACKWARD_NO_INTERRUPT`.

Avoid unnecessary allocations when comparing code objects.

Fix a crash when using a named unicode character like "\N{digit nine}" after the main interpreter has been initialized a second time.

WebAssembly cannot deal with bad function pointer casts (different count or types of arguments). Python can now use call trampolines to mitigate the problem. Define :c:macro:`PY_CALL_TRAMPOLINE` to enable call trampolines.

Some Windows system error codes(>= 10000) are now mapped into the correct errno and may now raise a subclass of :exc:`OSError`. Patch by Donghee Na.

Improve error messages in f-string syntax errors concerning empty expressions.

Fix a crash if we fail to decode characters in interactive mode if the tokenizer buffers are uninitialized. Patch by Pablo Galindo.

Speed up calls to c functions with keyword arguments by 25% with specialization. Patch by Kumar Aditya.

Replaced :opcode:`JUMP_ABSOLUTE` by the relative jump :opcode:`JUMP_BACKWARD`.

:c:func:`!PyFrame_FastToLocalsWithError` and :c:func:`!PyFrame_LocalsToFast` are no longer called during profiling nor tracing. C code can access the f_locals attribute of :c:type:`PyFrameObject` by calling :c:func:`PyFrame_GetLocals`.

Improve performance of array_inplace_repeat by reducing the number of invocations of memcpy. Refactor the repeat and inplace repeat methods of array, bytes, bytearray and unicodeobject to use the common _PyBytes_Repeat.

Reduce de-optimization in the specialized BINARY_OP_INPLACE_ADD_UNICODE opcode.

Remove the f_state field from the _PyInterpreterFrame struct. Add the owner field to the _PyInterpreterFrame struct to make ownership explicit to simplify clearing and deallocing frames and generators.

Check for the existence of the "sys/auxv.h" header in :mod:`faulthandler` to avoid compilation problems in systems where this header doesn't exist. Patch by Pablo Galindo

Use low bit of LOAD_GLOBAL to indicate whether to push a NULL before the global. Helps streamline the call sequence a bit.

Quicken bytecode in-place by storing it as part of the corresponding PyCodeObject.

Speed up iteration of :class:`bytes` and :class:`bytearray` by 30%. Patch by Kumar Aditya.

Improved the performance of :meth:`list.append` and list comprehensions by optimizing for the common case, where no resize is needed. Patch by Dennis Sweeney.

Improve performance of bytearray_repeat and bytearray_irepeat by reducing the number of invocations of memcpy.

Deprecate passing a message into :meth:`asyncio.Future.cancel` and :meth:`asyncio.Task.cancel`

Speed up :class:`bytearray` creation from :class:`list` and :class:`tuple` by 40%. Patch by Kumar Aditya.

Removed the __len__() call when initializing a list and moved initializing to list_extend. Patch by Jeremiah Pascual.

Speed up throwing exception in generator with :c:macro:`METH_FASTCALL` calling convention. Patch by Kumar Aditya.

Modify :opcode:`STORE_SUBSCR` to use an inline cache entry (rather than its oparg) as an adaptive counter.

Use inline caching for :opcode:`!PRECALL` and :opcode:`CALL`, and remove the internal machinery for managing the (now unused) non-inline caches.

Statically allocate and initialize the latin1 characters.

Improve syntax errors for incorrect function definitions. Patch by Pablo Galindo

Fix docstrings of :attr:`~property.getter`, :attr:`~property.setter`, and :attr:`~property.deleter` to clarify that they create a new copy of the property.

Make grammar changes required for PEP 646.

Allow vendors to override :const:`CTYPES_MAX_ARGCOUNT`.

:mod:`re` module: fix memory leak when a match is terminated by a signal or memory allocation failure. Patch by Ma Lin.

Allow overriding a future compliance check in :class:`asyncio.Task`.

When subprocess tries to use vfork, it now falls back to fork if vfork returns an error. This allows use in situations where vfork isn't allowed by the OS kernel.

Convert the :mod:`re` module into a package. Deprecate modules sre_compile, sre_constants and sre_parse.

Add :meth:`ZipFile.mkdir`

Fix :meth:`asyncio.loop.sock_connect` to only resolve names for :const:`socket.AF_INET` or :const:`socket.AF_INET6` families. Resolution may not make sense for other families, like :const:`socket.AF_BLUETOOTH` and :const:`socket.AF_UNIX`.

Adds the fully qualified test name to unittest output

Deprecate the aifc module.

Handle Ctrl+C in asyncio programs to interrupt the main task.

:const:`hashlib.algorithms_available` now lists only algorithms that are provided by activated crypto providers on OpenSSL 3.0. Legacy algorithms are not listed unless the legacy provider has been loaded into the default OSSL context.

All :exc:`URLError` exception messages raised in :class:`urllib.request.URLopener` now contain a colon between ftp error and the rest of the message. Previously, :func:`~urllib.request.URLopener.open_ftp` missed the colon. Patch by Oleg Iarygin.

Exception chaining is changed from :func:`Exception.with_traceback`/:func:`sys.exc_info` to PEP 3134. Patch by Oleg Iarygin.

:mod:`hashlib`'s internal _blake2 module now prefers libb2 from https://www.blake2.net/ over Python's vendored copy of blake2.

The Keccak Code Package for :mod:`hashlib`'s internal _sha3 module has been replaced with tiny_sha3. The module is used as fallback when Python is built without OpenSSL.

Implement :data:`typing.LiteralString`, part of PEP 675. Patch by Jelle Zijlstra.

Optimize :func:`re.search`, :func:`re.split`, :func:`re.findall`, :func:`re.finditer` and :func:`re.sub` for regular expressions starting with \A or ^.

Protect the :func:`re.finditer` iterator from re-entering.

Optimize calling GenericAlias objects by using PEP 590 vectorcall and by replacing PyObject_SetAttrString with PyObject_SetAttr.

Add the metadata_encoding parameter in the :class:`zipfile.ZipFile` constructor and the --metadata-encoding option in the :mod:`zipfile` CLI to allow reading zipfiles using non-standard codecs to encode the filenames within the archive.

Make :func:`io.text_encoding` returns "utf-8" when UTF-8 mode is enabled.

Fix thread safety of :meth:`zipfile._SharedFile.tell` to avoid a "zipfile.BadZipFile: Bad CRC-32 for file" exception when reading a :class:`ZipFile` from multiple threads.

Fix :func:`binascii.crc32` when it is compiled to use zlib'c crc32 to work properly on inputs 4+GiB in length instead of returning the wrong result. The workaround prior to this was to always feed the function data in increments smaller than 4GiB or to just call the zlib module function.

We also have :func:`binascii.crc32` release the GIL when computing on larger inputs as :func:`zlib.crc32` and :mod:`hashlib` do.

This also boosts performance on Windows as it now uses the zlib crc32 implementation for :func:`binascii.crc32` for a 2-3x speedup.

That the stdlib has a crc32 API in two modules is a known historical oddity. This moves us closer to a single implementation behind them.

Global inline flags (e.g. (?i)) can now only be used at the start of the regular expressions. Using them not at the start of expression was deprecated since Python 3.6.

A warning about inline flags not at the start of the regular expression now contains the position of the flag.

Add support of atomic grouping ((?>...)) and possessive quantifiers (*+, ++, ?+, {m,n}+) in :mod:`regular expressions <re>`.

Implement :class:`asyncio.Runner` context manager.

:func:`~dataclasses.dataclass` slots=True now correctly omits slots already defined in base classes. Patch by Arie Bovenberg.

Use FASTCALL convention for FutureIter.throw()

Deprecate the various modules listed by PEP 594:

aifc, asynchat, asyncore, audioop, cgi, cgitb, chunk, crypt, imghdr, msilib, nntplib, nis, ossaudiodev, pipes, smtpd, sndhdr, spwd, sunau, telnetlib, uu, xdrlib

Remove passing coroutine objects to :func:`asyncio.wait`.

Normalize repr() of asyncio future and task objects.

Fix bug where doctests using globals would fail when run multiple times.

Add :func:`hashlib.file_digest` helper for efficient hashing of file object.

Made cumtime the default sorting key for cProfile

Fix :class:`asyncio.Semaphore` re-aquiring FIFO order.

The :mod:`!asynchat`, :mod:`!asyncore` and :mod:`!smtpd` modules have been deprecated since at least Python 3.6. Their documentation and deprecation warnings and have now been updated to note they will removed in Python 3.12 (PEP 594).

Fix a crash when closing transports where the underlying socket handle is already invalid on the Proactor event loop.

:func:`select.select` now passes NULL to select for each empty fdset.

Apply bugfixes from importlib_metadata 4.11.3, including bugfix for EntryPoint.extras, which was returning match objects and not the extras strings.

Allow subclassing of :class:`typing.Any`. Patch by Shantanu Jain.

Deprecate missing :meth:`asyncio.Task.set_name` for third-party task implementations, schedule making it mandatory in Python 3.13.

Accept explicit contextvars.Context in :func:`asyncio.create_task` and :meth:`asyncio.loop.create_task`.

typing.get_args(typing.Tuple[()]) now returns () instead of ((),).

Add os.sysconf_names['SC_MINSIGSTKSZ'].

Upgrade pip wheel bundled with ensurepip (pip 22.0.4)

:mod:`faulthandler`: On Linux 5.14 and newer, dynamically determine size of signal handler stack size CPython allocates using getauxval(AT_MINSIGSTKSZ). This changes allows for Python extension's request to Linux kernel to use AMX_TILE instruction set on Sapphire Rapids Xeon processor to succeed, unblocking use of the ISA in frameworks.

The :data:`math.nan` value is now always available. Patch by Victor Stinner.

Expose :class:`asyncio.base_events.Server` as :class:`asyncio.Server`. Patch by Stefan Zabka.

The :mod:`signal` module no longer assumes that :const:`~signal.SIG_IGN` and :const:`~signal.SIG_DFL` are small int singletons.

Update bundled libexpat to 2.4.7

The :mod:`pwd` module is now optional. :func:`os.path.expanduser` returns the path when the :mod:`pwd` module is not available.

PEP 680, the :mod:`tomllib` module. Adds support for parsing TOML.

:func:`asyncio.timeout` and :func:`asyncio.timeout_at` context managers added. Patch by Tin Tvrtković and Andrew Svetlov.

Added raw datagram socket functions for asyncio: :meth:`~asyncio.AbstractEventLoop.sock_sendto`, :meth:`~asyncio.AbstractEventLoop.sock_recvfrom` and :meth:`~asyncio.AbstractEventLoop.sock_recvfrom_into`.

No longer require valid typeforms to be callable. This allows :data:`typing.Annotated` to wrap :data:`typing.ParamSpecArgs` and :data:`dataclasses.InitVar`. Patch by Gregory Beauregard.

Brings :class:`ParamSpec` propagation for :class:`GenericAlias` in line with :class:`Concatenate` (and others).

Define posix_venv and nt_venv :ref:`sysconfig installation schemes <installation_paths>` to be used for bootstrapping new virtual environments. Add venv sysconfig installation scheme to get the appropriate one of the above. The schemes are identical to the pre-existing posix_prefix and nt install schemes. The :mod:`venv` module now uses the venv scheme to create new virtual environments instead of hardcoding the paths depending only on the platform. Downstream Python distributors customizing the posix_prefix or nt install scheme in a way that is not compatible with the install scheme used in virtual environments are encouraged not to customize the venv schemes. When Python itself runs in a virtual environment, :func:`sysconfig.get_default_scheme` and :func:`sysconfig.get_preferred_scheme` with key="prefix" returns venv.

Implement support for PEP 646 in typing.py.

Allow unpacking types.GenericAlias objects, e.g. *tuple[int, str].

Warnings captured by the logging module are now logged without a format string to prevent systems that group logs by the msg argument from grouping captured warnings together.

:func:`typing.get_type_hints` now supports evaluating strings as forward references in :ref:`PEP 585 generic aliases <types-genericalias>`.

Add :exc:`DeprecationWarning` to :class:`!LegacyInterpolation`, deprecated in the docstring since Python 3.2. Will be removed in Python 3.13. Use :class:`BasicInterpolation` or :class:`ExtendedInterpolation` instead.

:mod:`pydoc` now excludes __future__ imports from the module's data items.

Add :func:`typing.assert_type`. Patch by Jelle Zijlstra.

Fix a unittest issue where if the command was invoked as python -m unittest and the filename(s) began with a dot (.), a ValueError is returned.

Add optional parameter dir_fd in :func:`shutil.rmtree`.

:meth:`!unittest.TestProgram.usageExit` is marked as deprecated, to be removed in Python 3.13.

Improve the error message when you try to subclass an instance of :class:`typing.NewType`.

Fix supporting generic aliases in :mod:`pydoc`.

Fix inconsistency with uppercase file extensions in :meth:`MimeTypes.guess_type`. Patch by Kumar Aditya.

Add LOCAL_CREDS, LOCAL_CREDS_PERSISTENT and SCM_CREDS2 FreeBSD constants to the socket module.

Fix .write() method of a member file in ZipFile, when the input data is an object that supports the buffer protocol, the file length may be wrong.

Fix handling of the stacklevel argument to logging functions in the :mod:`logging` module so that it is consistent across all logging functions and, as advertised, similar to the stacklevel argument used in :meth:`~warnings.warn`.

Fix bug where :mod:`unittest` sometimes drops frames from tracebacks of exceptions raised in tests.

Raise more accurate and PEP 249 compatible exceptions in :mod:`sqlite3`.

• Raise :exc:`~sqlite3.InterfaceError` instead of :exc:`~sqlite3.ProgrammingError` for SQLITE_MISUSE errors.
• Don't overwrite :exc:`BufferError` with :exc:`ValueError` when conversion to BLOB fails.
• Raise :exc:`~sqlite3.ProgrammingError` instead of :exc:`~sqlite3.Warning` if user tries to :meth:`~sqlite3.Cursor.execute` more than one SQL statement.
• Raise :exc:`~sqlite3.ProgrammingError` instead of :exc:`ValueError` if an SQL query contains null characters.

Add missing terminated NUL in sockaddr_un's length

This was potentially observable when using non-abstract AF_UNIX datagram sockets to processes written in another programming language.

Add :meth:`~sqlite3.Connection.serialize` and :meth:`~sqlite3.Connection.deserialize` support to :mod:`sqlite3`. Patch by Erlend E. Aasland.

Added :class:`ctypes.BigEndianUnion` and :class:`ctypes.LittleEndianUnion` classes, as originally documented in the library docs but not yet implemented.

Add an Barrier object in synchronization primitives of asyncio Lib in order to be consistent with Barrier from threading and multiprocessing libs*

:mod:`re` module, fix a few bugs about capturing group. In rare cases, capturing group gets an incorrect string. Patch by Ma Lin.

Document internal :mod:`asyncio` API.

Update PEP URLs to PEP 676's new canonical form.

Clarified the old Python versions compatibility note of :func:`binascii.crc32` / :func:`zlib.adler32` / :func:`zlib.crc32` functions.

Clarify for statement execution in its doc.

Adjust inaccurate phrasing in :doc:`../extending/newtypes_tutorial` about the ob_base field and the macros used to access its contents.

Document that in some circumstances :exc:`KeyboardInterrupt` may cause the code to enter an inconsistent state. Provided a sample workaround to avoid it if needed.

Link the errnos referenced in Doc/library/exceptions.rst to their respective section in Doc/library/errno.rst, and vice versa. Previously this was only done for EINTR and InterruptedError. Patch by Yan "yyyyyyyan" Orestes.

Skip test for :func:`~os.sched_getaffinity` and :func:`~os.sched_setaffinity` error case on FreeBSD.

Restore 'descriptions' when running tests internally.

Rewrite :func:`asyncio.to_thread` tests to use :class:`unittest.IsolatedAsyncioTestCase`.

The test suite is now passing on the Emscripten platform. All fork, socket, and subprocess-based tests are skipped.

Skip strftime("%4Y") feature test on Windows. It can cause an assertion error in debug builds.

Skip tests if platform's strftime does not support non-portable glibc extensions.

A test case for :func:`os.sendfile` is converted from deprecated :mod:`!asyncore` (see PEP 594) to :mod:`asyncio`. Patch by Oleg Iarygin.

Add configure option :option:`--enable-wasm-dynamic-linking` to enable dlopen and MAIN_MODULE / SIDE_MODULE on wasm32-emscripten.

makesetup now detects and skips all duplicated module definitions. The first entry wins.

Add SOABI wasm32-emscripten for Emscripten and wasm32-wasi for WASI on 32bit WASM as well as wasm64 counter parts.

Ensure Windows install builds fail correctly with a non-zero exit code when part of the build fails.

Update OpenSSL to 1.1.1n for macOS installers and all Windows builds.

The :mod:`tkinter` package now requires Tcl/Tk version 8.5.12 or newer.

Add regen-configure make target to regenerate configure script with Christian's container image quay.io/tiran/cpython_autoconf:269.

Building Python now requires support of IEEE 754 floating-point numbers. Patch by Victor Stinner.

configure now verifies that all SQLite C APIs needed for the :mod:`sqlite3` extension module are found.

Update zlib to v1.2.12 to resolve :cve:`2018-25032`.

Enables installing the :file:`py.exe` launcher on Windows ARM64.

Upgraded :ref:`launcher` to support a new -V:company/tag argument for full PEP 514 support and to detect ARM64 installs. The -64 suffix on arguments is deprecated, but still selects any non-32-bit install. Setting :envvar:`PYLAUNCHER_ALLOW_INSTALL` and specifying a version that is not installed will attempt to install the requested version from the Microsoft Store.

The installer for Windows now includes documentation as loose HTML files rather than a single compiled :file:`.chm` file.

Update Windows installer to use SQLite 3.38.1.

Update bzip2 to 1.0.8 in Windows builds to mitigate :cve:`2016-3189` and :cve:`2019-12900`.

Prevent :cve:`2022-26488` by ensuring the Add to PATH option in the Windows installer uses the correct path when being repaired.

Fix a regression in the setting of sys._base_executable in framework builds, and thereby fix a regression in :mod:`venv` virtual environments with such builds.

Update macOS installer to SQLite 3.38.1.

Replace Emscripten's limited shell with Katie Bell's browser-ui REPL from python-wasm project.

Add PyFrame_GetBuiltins, PyFrame_GetGenerator and PyFrame_GetGlobals C-API functions to access frame object attributes safely from C code.

Move the private _PyFrameEvalFunction type, and private _PyInterpreterState_GetEvalFrameFunc() and _PyInterpreterState_SetEvalFrameFunc() functions to the internal C API. The _PyFrameEvalFunction callback function type now uses the _PyInterpreterFrame type which is part of the internal C API. Patch by Victor Stinner.

Move the private undocumented _PyEval_EvalFrameDefault() function to the internal C API. The function now uses the _PyInterpreterFrame type which is part of the internal C API. Patch by Victor Stinner.

Remove the private undocumented function _PyEval_CallTracing() from the C API. Call the public :func:`sys.call_tracing` function instead. Patch by Victor Stinner.

Remove the private undocumented function _PyEval_GetCoroutineOriginTrackingDepth() from the C API. Call the public :func:`sys.get_coroutine_origin_tracking_depth` function instead. Patch by Victor Stinner.

Remove the following private undocumented functions from the C API:

• _PyEval_GetAsyncGenFirstiter()
• _PyEval_GetAsyncGenFinalizer()
• _PyEval_SetAsyncGenFirstiter()
• _PyEval_SetAsyncGenFinalizer()

Call the public :func:`sys.get_asyncgen_hooks` and :func:`sys.set_asyncgen_hooks` functions instead. Patch by Victor Stinner.

Remove private functions _PySys_GetObjectId() and _PySys_SetObjectId(). Patch by Donghee Na.

Add new functions to pack and unpack C double (serialize and deserialize): :c:func:`PyFloat_Pack2`, :c:func:`PyFloat_Pack4`, :c:func:`PyFloat_Pack8`, :c:func:`PyFloat_Unpack2`, :c:func:`PyFloat_Unpack4` and :c:func:`PyFloat_Unpack8`. Patch by Victor Stinner.