What's New In Python 3.13
*************************

Editor:
   TBD

This article explains the new features in Python 3.13, compared to
3.12.

For full details, see the changelog.

注釈:

  Prerelease users should be aware that this document is currently in
  draft form. It will be updated substantially as Python 3.13 moves
  towards release, so it's worth checking back even after reading
  earlier versions.


Summary -- Release highlights
=============================

Important deprecations, removals or restrictions:

* PEP 594: The remaining 19 "dead batteries" have been removed from
  the standard library: "aifc", "audioop", "cgi", "cgitb", "chunk",
  "crypt", "imghdr", "mailcap", "msilib", "nis", "nntplib",
  "ossaudiodev", "pipes", "sndhdr", "spwd", "sunau", "telnetlib", "uu"
  and "xdrlib".

* **PEP 602** ("Annual Release Cycle for Python") has been updated:

  * Python 3.9 - 3.12 have one and a half years of full support,
    followed by three and a half years of security fixes.

  * Python 3.13 and later have two years of full support, followed by
    three years of security fixes.

Interpreter improvements:

* A basic JIT compiler was added. It is currently disabled by default
  (though we may turn it on later). Performance improvements are
  modest -- we expect to be improving this over the next few releases.


New Features
============


Improved Error Messages
-----------------------

* The interpreter now colorizes error messages when displaying
  tracebacks by default. This feature can be controlled via the new
  "PYTHON_COLORS" environment variable as well as the canonical
  "NO_COLOR" and "FORCE_COLOR" environment variables. See also
  Controlling color. (Contributed by Pablo Galindo Salgado in
  gh-112730.)

* When an incorrect keyword argument is passed to a function, the
  error message now potentially suggests the correct keyword argument.
  (Contributed by Pablo Galindo Salgado and Shantanu Jain in
  gh-107944.)

  >>> "better error messages!".split(max_split=1)
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
      "better error messages!".split(max_split=1)
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  TypeError: split() got an unexpected keyword argument 'max_split'. Did you mean 'maxsplit'?


Incremental Garbage Collection
------------------------------

* The cycle garbage collector is now incremental. This means that
  maximum pause times are reduced by an order of magnitude or more for
  larger heaps.


Other Language Changes
======================

* Allow the *count* argument of "str.replace()" to be a keyword.
  (Contributed by Hugo van Kemenade in gh-106487.)

* Compiler now strip indents from docstrings. This will reduce the
  size of *bytecode cache* (e.g. ".pyc" file). For example, cache file
  size for "sqlalchemy.orm.session" in SQLAlchemy 2.0 is reduced by
  about 5%. This change will affect tools using docstrings, like
  "doctest". (Contributed by Inada Naoki in gh-81283.)

* 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. (Contributed by Irit Katriel in
  gh-108113).

* "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. (Contributed by Victor Stinner in gh-109649.)

* "os.path.realpath()" now resolves MS-DOS style file names even if
  the file is not accessible. (Contributed by Moonsik Park in
  gh-82367.)

* Fixed a bug where a "global" declaration in an "except" block is
  rejected when the global is used in the "else" block. (Contributed
  by Irit Katriel in gh-111123.)

* Many functions now emit a warning if a boolean value is passed as a
  file descriptor argument. This can help catch some errors earlier.
  (Contributed by Serhiy Storchaka in gh-82626.)

* 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. (Contributed by Yilei Yang in gh-111374.)

* The new "PYTHON_HISTORY" environment variable can be used to change
  the location of a ".python_history" file. (Contributed by Levi
  Sabah, Zackery Spytz and Hugo van Kemenade in gh-73965.)

* Add "PythonFinalizationError" exception. This exception derived from
  "RuntimeError" is raised when an operation is blocked during the
  *Python finalization*.

  The following functions now raise PythonFinalizationError, instead
  of "RuntimeError":

  * "_thread.start_new_thread()".

  * "subprocess.Popen".

  * "os.fork()".

  * "os.forkpty()".

  (Contributed by Victor Stinner in gh-114570.)

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

  * "xml.etree.ElementTree.XMLParser.flush()"

  * "xml.etree.ElementTree.XMLPullParser.flush()"

  * "xml.parsers.expat.xmlparser.GetReparseDeferralEnabled()"

  * "xml.parsers.expat.xmlparser.SetReparseDeferralEnabled()"

  * "xml.sax.expatreader.ExpatParser.flush()"

  (Contributed by Sebastian Pipping in gh-115623.)

* When "asyncio.TaskGroup.create_task()" is called on an inactive
  "asyncio.TaskGroup", the given coroutine will be closed (which
  prevents a "RuntimeWarning" about the given coroutine being never
  awaited).

  (Contributed by Arthur Tacca and Jason Zhang in gh-115957.)

* The "ssl.create_default_context()" API now includes
  "ssl.VERIFY_X509_PARTIAL_CHAIN" and "ssl.VERIFY_X509_STRICT" in its
  default flags.

  注釈:

    "ssl.VERIFY_X509_STRICT" may reject pre-**RFC 5280** or malformed
    certificates that the underlying OpenSSL implementation otherwise
    would accept. While disabling this is not recommended, you can do
    so using:

       ctx = ssl.create_default_context()
       ctx.verify_flags &= ~ssl.VERIFY_X509_STRICT

  (Contributed by William Woodruff in gh-112389.)

* The "configparser.ConfigParser" now accepts unnamed sections before
  named
     ones if configured to do so.

     (Contributed by Pedro Sousa Lacerda in gh-66449)


New Modules
===========

* None yet.


Improved Modules
================


argparse
--------

* Add parameter *deprecated* in methods "add_argument()" and
  "add_parser()" which allows to deprecate command-line options,
  positional arguments and subcommands. (Contributed by Serhiy
  Storchaka in gh-83648).


array
-----

* Add "'w'" type code ("Py_UCS4") that can be used for Unicode
  strings. It can be used instead of "'u'" type code, which is
  deprecated. (Contributed by Inada Naoki in gh-80480.)

* Add "clear()" method in order to implement "MutableSequence".
  (Contributed by Mike Zimin in gh-114894.)


ast
---

* The constructors of node types in the "ast" module are now stricter
  in the arguments they accept, and have more intuitive behaviour when
  arguments are omitted.

  If an optional field on an AST node is not included as an argument
  when constructing an instance, the field will now be set to "None".
  Similarly, if a list field is omitted, that field will now be set to
  an empty list. (Previously, in both cases, the attribute would be
  missing on the newly constructed AST node instance.)

  If other arguments are omitted, a "DeprecationWarning" is emitted.
  This will cause an exception in Python 3.15. Similarly, passing a
  keyword argument that does not map to a field on the AST node is now
  deprecated, and will raise an exception in Python 3.15.

* "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". (Contributed by Irit Katriel in
  gh-108113.)


asyncio
-------

* "asyncio.loop.create_unix_server()" will now automatically remove
  the Unix socket when the server is closed. (Contributed by Pierre
  Ossman in gh-111246.)

* "asyncio.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. (Contributed by Jamie Phan in gh-115199.)

* Add "asyncio.Server.close_clients()" and
  "asyncio.Server.abort_clients()" methods which allow to more
  forcefully close an asyncio server. (Contributed by Pierre Ossman in
  gh-113538.)

* "asyncio.as_completed()" now returns an object that is both an
  *asynchronous iterator* and a plain *iterator* of awaitables. The
  awaitables yielded by asynchronous iteration include original task
  or future objects that were passed in, making it easier to associate
  results with the tasks being completed. (Contributed by Justin
  Arthur in gh-77714.)

* Add "asyncio.Queue.shutdown()" (along with "asyncio.QueueShutDown")
  for queue termination. (Contributed by Laurie Opperman and Yves
  Duprat in gh-104228.)


base64
------

* Add "base64.z85encode()" and "base64.z85decode()" functions which
  allow encoding and decoding z85 data. See Z85  specification for
  more information. (Contributed by Matan Perelman in gh-75299.)


copy
----

* Add "copy.replace()" function which allows to create a modified copy
  of an object, which is especially useful for immutable objects. It
  supports named tuples created with the factory function
  "collections.namedtuple()", "dataclass" instances, various
  "datetime" objects, "Signature" objects, "Parameter" objects, code
  object, and any user classes which define the "__replace__()"
  method. (Contributed by Serhiy Storchaka in gh-108751.)


dbm
---

* Add "dbm.gnu.gdbm.clear()" and "dbm.ndbm.ndbm.clear()"  methods that
  remove all items from the database. (Contributed by Donghee Na in
  gh-107122.)


dis
---

* Change the output of "dis" module functions to show logical labels
  for jump targets and exception handlers, rather than offsets. The
  offsets can be added with the new "-O" command line option or the
  "show_offsets" parameter. (Contributed by Irit Katriel in
  gh-112137.)


dbm
---

* Add "dbm.gnu.gdbm.clear()" and "dbm.ndbm.ndbm.clear()"  methods that
  remove all items from the database. (Contributed by Donghee Na in
  gh-107122.)

* Add new "dbm.sqlite3" backend, and make it the default "dbm"
  backend. (Contributed by Raymond Hettinger and Erlend E. Aasland in
  gh-100414.)


doctest
-------

* The "doctest.DocTestRunner.run()" method now counts the number of
  skipped tests. Add "doctest.DocTestRunner.skips" and
  "doctest.TestResults.skipped" attributes. (Contributed by Victor
  Stinner in gh-108794.)


email
-----

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


fractions
---------

* Formatting for objects of type "fractions.Fraction" now supports the
  standard format specification mini-language rules for fill,
  alignment, sign handling, minimum width and grouping. (Contributed
  by Mark Dickinson in gh-111320.)


gc
--

* The cyclic garbage collector is now incremental, which changes the
  meanings of the results of "gc.get_threshold()" and
  "gc.get_threshold()" as well as "gc.get_count()" and
  "gc.get_stats()".

* "gc.get_threshold()" returns a three-tuple for backwards
  compatibility, the first value is the threshold for young
  collections, as before, the second value determines the rate at
  which the old collection is scanned; the default is 10 and higher
  values mean that the old collection is scanned more slowly. The
  third value is meangless and is always zero.

* "gc.set_threshold()" ignores any items after the second.

* "gc.get_count()" and "gc.get_stats()". These functions return the
  same format of results as before. The only difference is that
  instead of the results refering to the young, aging and old
  generations, the results refer to the young generation and the aging
  and collecting spaces of the old generation.

In summary, code that attempted to manipulate the behavior of the
cycle GC may not work exactly as intended, but it is very unlikely to
harmful. All other code will work just fine.


glob
----

* Add "glob.translate()" function that converts a path specification
  with shell-style wildcards to a regular expression. (Contributed by
  Barney Gale in gh-72904.)


io
--

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. (Contributed by Victor Stinner in gh-62948.)


importlib
---------

Previously deprecated "importlib.resources" functions are un-
deprecated:

   * "is_resource()"

   * "open_binary()"

   * "open_text()"

   * "path()"

   * "read_binary()"

   * "read_text()"

All now allow for a directory (or tree) of resources, using multiple
positional arguments.

For text-reading functions, the *encoding* and *errors* must now be
given as keyword arguments.

The "contents()" remains deprecated in favor of the full-featured
"Traversable" API. However, there is now no plan to remove it.

(Contributed by Petr Viktorin in gh-106532.)


ipaddress
---------

* Add the "ipaddress.IPv4Address.ipv6_mapped" property, which returns
  the IPv4-mapped IPv6 address. (Contributed by Charles Machalow in
  gh-109466.)

* Fix "is_global" and "is_private" behavior in "IPv4Address",
  "IPv6Address", "IPv4Network" and "IPv6Network".


itertools
---------

* Added a "strict" option to "itertools.batched()". This raises a
  "ValueError" if the final batch is shorter than the specified batch
  size. (Contributed by Raymond Hettinger in gh-113202.)


marshal
-------

* Add the *allow_code* parameter in module functions. Passing
  "allow_code=False" prevents serialization and de-serialization of
  code objects which are incompatible between Python versions.
  (Contributed by Serhiy Storchaka in gh-113626.)


math
----

A new function "fma()" for fused multiply-add operations has been
added. This function computes "x * y + z" with only a single round,
and so avoids any intermediate loss of precision. It wraps the "fma()"
function provided by C99, and follows the specification of the IEEE
754 "fusedMultiplyAdd" operation for special cases. (Contributed by
Mark Dickinson and Victor Stinner in gh-73468.)


mmap
----

* The "mmap.mmap" class now has an "seekable()" method that can be
  used when a seekable file-like object is required. The "seek()"
  method now returns the new absolute position. (Contributed by
  Donghee Na and Sylvie Liberman in gh-111835.)

* "mmap.mmap" now has a *trackfd* parameter on Unix; if it is "False",
  the file descriptor specified by *fileno* will not be duplicated.
  (Contributed by Zackery Spytz and Petr Viktorin in gh-78502.)


opcode
------

* Move "opcode.ENABLE_SPECIALIZATION" to
  "_opcode.ENABLE_SPECIALIZATION". This field was added in 3.12, it
  was never documented and is not intended for external usage.
  (Contributed by Irit Katriel in gh-105481.)

* Removed "opcode.is_pseudo", "opcode.MIN_PSEUDO_OPCODE" and
  "opcode.MAX_PSEUDO_OPCODE", which were added in 3.12, were never
  documented or exposed through "dis", and were not intended to be
  used externally.


os
--

* Add "os.process_cpu_count()" function to get the number of logical
  CPUs usable by the calling thread of the current process.
  (Contributed by Victor Stinner in gh-109649.)

* Add a low level interface for Linux's timer notification file
  descriptors via "os.timerfd_create()", "os.timerfd_settime()",
  "os.timerfd_settime_ns()", "os.timerfd_gettime()", and
  "os.timerfd_gettime_ns()", "os.TFD_NONBLOCK", "os.TFD_CLOEXEC",
  "os.TFD_TIMER_ABSTIME", and "os.TFD_TIMER_CANCEL_ON_SET"
  (Contributed by Masaru Tsuchiyama in gh-108277.)

* "os.cpu_count()" and "os.process_cpu_count()" can be overridden
  through the new environment variable "PYTHON_CPU_COUNT" or the new
  command-line option "-X 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). (Contributed by Donghee
  Na in gh-109595.)

* 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.
  (Contributed by Serhiy Storchaka in gh-59616.)

* Add support of "os.fchmod()" and a file descriptor in "os.chmod()"
  on Windows. (Contributed by Serhiy Storchaka in gh-113191.)

* "os.posix_spawn()" now accepts "env=None", which makes the newly
  spawned process use the current process environment. (Contributed by
  Jakub Kulik in gh-113119.)

* "os.posix_spawn()" gains an "os.POSIX_SPAWN_CLOSEFROM" attribute for
  use in "file_actions=" on platforms that support
  "posix_spawn_file_actions_addclosefrom_np()". (Contributed by Jakub
  Kulik in gh-113117.)


os.path
-------

* Add "os.path.isreserved()" to check if a path is reserved on the
  current system. This function is only available on Windows.
  (Contributed by Barney Gale in gh-88569.)

* On Windows, "os.path.isabs()" no longer considers paths starting
  with exactly one (back)slash to be absolute. (Contributed by Barney
  Gale and Jon Foster in gh-44626.)


pathlib
-------

* Add "pathlib.UnsupportedOperation", which is raised instead of
  "NotImplementedError" when a path operation isn't supported.
  (Contributed by Barney Gale in gh-89812.)

* Add "pathlib.Path.from_uri()", a new constructor to create a
  "pathlib.Path" object from a 'file' URI ("file://"). (Contributed by
  Barney Gale in gh-107465.)

* Add "pathlib.PurePath.full_match()" for matching paths with shell-
  style wildcards, including the recursive wildcard ""**"".
  (Contributed by Barney Gale in gh-73435.)

* Add "pathlib.PurePath.parser" class attribute that stores the
  implementation of "os.path" used for low-level path parsing and
  joining: either "posixpath" or "ntpath".

* Add *recurse_symlinks* keyword-only argument to
  "pathlib.Path.glob()" and "rglob()". (Contributed by Barney Gale in
  gh-77609).

* Add *follow_symlinks* keyword-only argument to "is_file()",
  "is_dir()", "owner()", "group()". (Contributed by Barney Gale in
  gh-105793, and Kamil Turek in gh-107962).

* Return files and directories from "pathlib.Path.glob()" and
  "rglob()" when given a pattern that ends with ""**"". In earlier
  versions, only directories were returned. (Contributed by Barney
  Gale in gh-70303).


pdb
---

* Add ability to move between chained exceptions during post mortem
  debugging in "pm()" using the new "exceptions [exc_number]" command
  for Pdb. (Contributed by Matthias Bussonnier in gh-106676.)

* Expressions/statements whose prefix is a pdb command are now
  correctly identified and executed. (Contributed by Tian Gao in
  gh-108464.)

* "sys.path[0]" will no longer be replaced by the directory of the
  script being debugged when "sys.flags.safe_path" is set (via the
  "-P" command line option or "PYTHONSAFEPATH" environment variable).
  (Contributed by Tian Gao and Christian Walther in gh-111762.)


queue
-----

* Add "queue.Queue.shutdown()" (along with "queue.ShutDown") for queue
  termination. (Contributed by Laurie Opperman and Yves Duprat in
  gh-104750.)


re
--

* Rename "re.error" to "re.PatternError" for improved clarity.
  "re.error" is kept for backward compatibility.


sqlite3
-------

* A "ResourceWarning" is now emitted if a "sqlite3.Connection" object
  is not "closed" explicitly. (Contributed by Erlend E. Aasland in
  gh-105539.)

* Add *filter* keyword-only parameter to
  "sqlite3.Connection.iterdump()" for filtering database objects to
  dump. (Contributed by Mariusz Felisiak in gh-91602.)


statistics
----------

* Add "statistics.kde()" for kernel density estimation. This makes it
  possible to estimate a continuous probability density function from
  a fixed number of discrete samples. (Contributed by Raymond
  Hettinger in gh-115863.)


subprocess
----------

* The "subprocess" module now uses the "os.posix_spawn()" function in
  more situations.  Notably in the default case of "close_fds=True" on
  more recent versions of platforms including Linux, FreeBSD, and
  Solaris where the C library provides
  "posix_spawn_file_actions_addclosefrom_np()". On Linux this should
  perform similar to our existing Linux "vfork()" based code.  A
  private control knob "subprocess._USE_POSIX_SPAWN" can be set to
  "False" if you need to force "subprocess" not to ever use
  "os.posix_spawn()".  Please report your reason and platform details
  in the CPython issue tracker if you set this so that we can improve
  our API selection logic for everyone. (Contributed by Jakub Kulik in
  gh-113117.)


sys
---

* Add the "sys._is_interned()" function to test if the string was
  interned. This function is not guaranteed to exist in all
  implementations of Python. (Contributed by Serhiy Storchaka in
  gh-78573.)


time
----

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

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


tkinter
-------

* Add "tkinter" widget methods: "tk_busy_hold()",
  "tk_busy_configure()", "tk_busy_cget()", "tk_busy_forget()",
  "tk_busy_current()", and "tk_busy_status()". (Contributed by Miguel,
  klappnase and Serhiy Storchaka in gh-72684.)

* The "tkinter" widget method "wm_attributes()" now accepts the
  attribute name without the minus prefix to get window attributes,
  e.g. "w.wm_attributes('alpha')" and allows to specify attributes and
  values to set as keyword arguments, e.g.
  "w.wm_attributes(alpha=0.5)". Add new optional keyword-only
  parameter *return_python_dict*: calling
  "w.wm_attributes(return_python_dict=True)" returns the attributes as
  a dict instead of a tuple. (Contributed by Serhiy Storchaka in
  gh-43457.)

* Add new optional keyword-only parameter *return_ints* in the
  "Text.count()" method. Passing "return_ints=True" makes it always
  returning the single count as an integer instead of a 1-tuple or
  "None". (Contributed by Serhiy Storchaka in gh-97928.)

* Add support of the "vsapi" element type in the "element_create()"
  method of "tkinter.ttk.Style". (Contributed by Serhiy Storchaka in
  gh-68166.)


traceback
---------

* Add *show_group* parameter to
  "traceback.TracebackException.format_exception_only()" to format the
  nested exceptions of a "BaseExceptionGroup" instance, recursively.
  (Contributed by Irit Katriel in gh-105292.)

* Add the field *exc_type_str* to "TracebackException", which holds a
  string display of the *exc_type*. Deprecate the field *exc_type*
  which holds the type object itself. Add parameter *save_exc_type*
  (default "True") to indicate whether "exc_type" should be saved.
  (Contributed by Irit Katriel in gh-112332.)


typing
------

* 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". (Contributed by Jelle
  Zijlstra in gh-104873.)

* Add "typing.ReadOnly", a special typing construct to mark an item of
  a "typing.TypedDict" as read-only for type checkers. See **PEP 705**
  for more details.


unicodedata
-----------

* The Unicode database has been updated to version 15.1.0.
  (Contributed by James Gerity in gh-109559.)


venv
----

* Add support for adding source control management (SCM) ignore files
  to a virtual environment's directory. By default, Git is supported.
  This is implemented as opt-in via the API which can be extended to
  support other SCMs ("venv.EnvBuilder" and "venv.create()"), and opt-
  out via the CLI (using "--without-scm-ignore-files"). (Contributed
  by Brett Cannon in gh-108125.)


warnings
--------

* The new "warnings.deprecated()" decorator provides a way to
  communicate deprecations to *static type checkers* and to warn on
  usage of deprecated classes and functions. A runtime deprecation
  warning may also be emitted when a decorated function or class is
  used at runtime. See **PEP 702**. (Contributed by Jelle Zijlstra in
  gh-104003.)


xml.etree.ElementTree
---------------------

* Add the "close()" method for the iterator returned by "iterparse()"
  for explicit cleaning up. (Contributed by Serhiy Storchaka in
  gh-69893.)


zipimport
---------

* Gains support for ZIP64 format files.  Everybody loves huge code
  right? (Contributed by Tim Hatch in gh-94146.)


Optimizations
=============

* "textwrap.indent()" is now ~30% faster than before for large input.
  (Contributed by Inada Naoki in gh-107369.)

* The "subprocess" module uses "os.posix_spawn()" in more situations
  including the default where "close_fds=True" on many modern
  platforms.  This should provide a noteworthy performance increase
  launching processes on FreeBSD and Solaris.  See the "subprocess"
  section above for details. (Contributed by Jakub Kulik in
  gh-113117.)


Experimental JIT Compiler
=========================

When CPython is configured using the "--enable-experimental-jit"
option, a just-in-time compiler is added which can speed up some
Python programs.

The internal architecture is roughly as follows.

* We start with specialized *Tier 1 bytecode*. See What's new in 3.11
  for details.

* When the Tier 1 bytecode gets hot enough, it gets translated to a
  new, purely internal *Tier 2 IR*, a.k.a. micro-ops ("uops").

* The Tier 2 IR uses the same stack-based VM as Tier 1, but the
  instruction format is better suited to translation to machine code.

* We have several optimization passes for Tier 2 IR, which are applied
  before it is interpreted or translated to machine code.

* There is a Tier 2 interpreter, but it is mostly intended for
  debugging the earlier stages of the optimization pipeline. If the
  JIT is not enabled, the Tier 2 interpreter can be invoked by passing
  Python the "-X uops" option or by setting the "PYTHON_UOPS"
  environment variable to "1".

* When the "--enable-experimental-jit" option is used, the optimized
  Tier 2 IR is translated to machine code, which is then executed.
  This does not require additional runtime options.

* The machine code translation process uses an architecture called
  *copy-and-patch*. It has no runtime dependencies, but there is a new
  build-time dependency on LLVM.

(JIT by Brandt Bucher, inspired by a paper by Haoran Xu and Fredrik
Kjolstad. Tier 2 IR by Mark Shannon and Guido van Rossum. Tier 2
optimizer by Ken Jin.)


Deprecated
==========

* "array": "array"'s "'u'" format code, deprecated in docs since
  Python 3.3, emits "DeprecationWarning" since 3.13 and will be
  removed in Python 3.16. Use the "'w'" format code instead.
  (contributed by Hugo van Kemenade in gh-80480)

* "ctypes": Deprecate undocumented "ctypes.SetPointerType()" and
  "ctypes.ARRAY()" functions. Replace "ctypes.ARRAY(item_type, size)"
  with "item_type * size". (Contributed by Victor Stinner in
  gh-105733.)

* "decimal": Deprecate non-standard format specifier "N" for
  "decimal.Decimal". It was not documented and only supported in the C
  implementation. (Contributed by Serhiy Storchaka in gh-89902.)

* "dis": The "dis.HAVE_ARGUMENT" separator is deprecated. Check
  membership in "hasarg" instead. (Contributed by Irit Katriel in
  gh-109319.)

* "getopt" and "optparse" modules: They are now *soft deprecated*: the
  "argparse" module should be used for new projects. Previously, the
  "optparse" module was already deprecated, its removal was not
  scheduled, and no warnings was emitted: so there is no change in
  practice. (Contributed by Victor Stinner in gh-106535.)

* "gettext": Emit deprecation warning for non-integer numbers in
  "gettext" functions and methods that consider plural forms even if
  the translation was not found. (Contributed by Serhiy Storchaka in
  gh-88434.)

* "glob": The undocumented "glob.glob0()" and "glob.glob1()" functions
  are deprecated. Use "glob.glob()" and pass a directory to its
  *root_dir* argument instead. (Contributed by Barney Gale in
  gh-117337.)

* "http.server": "http.server.CGIHTTPRequestHandler" now emits a
  "DeprecationWarning" as it will be removed in 3.15.  Process-based
  CGI HTTP servers have been out of favor for a very long time.  This
  code was outdated, unmaintained, and rarely used.  It has a high
  potential for both security and functionality bugs.  This includes
  removal of the "--cgi" flag to the "python -m http.server" command
  line in 3.15.

* "pathlib": "pathlib.PurePath.is_reserved()" is deprecated and
  scheduled for removal in Python 3.15. Use "os.path.isreserved()" to
  detect reserved paths on Windows.

* "pydoc": Deprecate undocumented "pydoc.ispackage()" function.
  (Contributed by Zackery Spytz in gh-64020.)

* "sqlite3": 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.

  Deprecate passing name, number of arguments, and the callable as
  keyword arguments for the following "sqlite3.Connection" APIs:

  * "create_function()"

  * "create_aggregate()"

  Deprecate passing the callback callable by keyword for the following
  "sqlite3.Connection" APIs:

  * "set_authorizer()"

  * "set_progress_handler()"

  * "set_trace_callback()"

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

  (Contributed by Erlend E. Aasland in gh-107948 and gh-108278.)

* "sys": "sys._enablelegacywindowsfsencoding()" function. Replace it
  with the "PYTHONLEGACYWINDOWSFSENCODING" environment variable.
  (Contributed by Inada Naoki in gh-73427.)

* "traceback": The field *exc_type* of "traceback.TracebackException"
  is deprecated. Use *exc_type_str* instead.

* "typing":

  * Creating a "typing.NamedTuple" class using keyword arguments to
    denote the fields ("NT = NamedTuple("NT", x=int, y=int)") is
    deprecated, and will be disallowed in Python 3.15. Use the class-
    based syntax or the functional syntax instead. (Contributed by
    Alex Waygood in gh-105566.)

  * When using the functional syntax to create a "typing.NamedTuple"
    class or a "typing.TypedDict" class, failing to pass a value to
    the 'fields' parameter ("NT = NamedTuple("NT")" or "TD =
    TypedDict("TD")") is deprecated. Passing "None" to the 'fields'
    parameter ("NT = NamedTuple("NT", None)" or "TD = TypedDict("TD",
    None)") is also deprecated. Both will be disallowed in Python
    3.15. To create a NamedTuple class with 0 fields, use "class
    NT(NamedTuple): pass" or "NT = NamedTuple("NT", [])". To create a
    TypedDict class with 0 fields, use "class TD(TypedDict): pass" or
    "TD = TypedDict("TD", {})". (Contributed by Alex Waygood in
    gh-105566 and gh-105570.)

  * "typing.no_type_check_decorator()" is deprecated, and scheduled
    for removal in Python 3.15. After eight years in the "typing"
    module, it has yet to be supported by any major type checkers.
    (Contributed by Alex Waygood in gh-106309.)

  * "typing.AnyStr" is deprecated. In Python 3.16, it will be removed
    from "typing.__all__", and a "DeprecationWarning" will be emitted
    when it is imported or accessed. It will be removed entirely in
    Python 3.18. Use the new type parameter syntax instead.
    (Contributed by Michael The in gh-107116.)

* "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. (Contributed by Victor Stinner in
  gh-105096.)

* Calling "frame.clear()" on a suspended frame raises "RuntimeError"
  (as has always been the case for an executing frame). (Contributed
  by Irit Katriel in gh-79932.)

* Assignment to a function's "__code__" attribute where the new code
  object's type does not match the function's type, is deprecated. The
  different types are: plain function, generator, async generator and
  coroutine. (Contributed by Irit Katriel in gh-81137.)

* The undocumented and unused "tarfile" attribute of "tarfile.TarFile"
  is deprecated and scheduled for removal in Python 3.16.

* "platform.java_ver()" is deprecated and will be removed in 3.15. It
  was largely untested, had a confusing API, and was only useful for
  Jython support. (Contributed by Nikita Sobolev in gh-116349.)


Pending Removal in Python 3.14
------------------------------

* "argparse": The *type*, *choices*, and *metavar* parameters of
  "argparse.BooleanOptionalAction" are deprecated and will be removed
  in 3.14. (Contributed by Nikita Sobolev in gh-92248.)

* "ast": The following features have been deprecated in documentation
  since Python 3.8, now cause a "DeprecationWarning" to be emitted at
  runtime when they are accessed or used, and will be removed in
  Python 3.14:

  * "ast.Num"

  * "ast.Str"

  * "ast.Bytes"

  * "ast.NameConstant"

  * "ast.Ellipsis"

  Use "ast.Constant" instead. (Contributed by Serhiy Storchaka in
  gh-90953.)

* "collections.abc": Deprecated "ByteString". Prefer "Sequence" or
  "Buffer". For use in typing, prefer a union, like "bytes |
  bytearray", or "collections.abc.Buffer". (Contributed by Shantanu
  Jain in gh-91896.)

* "email": Deprecated the *isdst* parameter in
  "email.utils.localtime()". (Contributed by Alan Williams in
  gh-72346.)

* "importlib": "__package__" and "__cached__" will cease to be set or
  taken into consideration by the import system (gh-97879).

* "importlib.abc" deprecated classes:

  * "importlib.abc.ResourceReader"

  * "importlib.abc.Traversable"

  * "importlib.abc.TraversableResources"

  Use "importlib.resources.abc" classes instead:

  * "importlib.resources.abc.Traversable"

  * "importlib.resources.abc.TraversableResources"

  (Contributed by Jason R. Coombs and Hugo van Kemenade in gh-93963.)

* "itertools" had undocumented, inefficient, historically buggy, and
  inconsistent support for copy, deepcopy, and pickle operations. This
  will be removed in 3.14 for a significant reduction in code volume
  and maintenance burden. (Contributed by Raymond Hettinger in
  gh-101588.)

* "multiprocessing": The default start method will change to a safer
  one on Linux, BSDs, and other non-macOS POSIX platforms where
  "'fork'" is currently the default (gh-84559). Adding a runtime
  warning about this was deemed too disruptive as the majority of code
  is not expected to care. Use the "get_context()" or
  "set_start_method()" APIs to explicitly specify when your code
  *requires* "'fork'".  See コンテキストと開始方式.

* "pathlib": "is_relative_to()" and "relative_to()": passing
  additional arguments is deprecated.

* "pkgutil": "find_loader()" and "get_loader()" now raise
  "DeprecationWarning"; use "importlib.util.find_spec()" instead.
  (Contributed by Nikita Sobolev in gh-97850.)

* "pty":

  * "master_open()": use "pty.openpty()".

  * "slave_open()": use "pty.openpty()".

* "shutil.rmtree()" *onerror* parameter is deprecated in 3.12, and
  will be removed in 3.14: use the *onexc* parameter instead.

* "sqlite3":

  * "version" and "version_info".

  * "execute()" and "executemany()" if named placeholders are used and
    *parameters* is a sequence instead of a "dict".

  * date and datetime adapter, date and timestamp converter: see the
    "sqlite3" documentation for suggested replacement recipes.

* "types.CodeType": Accessing "co_lnotab" was deprecated in **PEP
  626** since 3.10 and was planned to be removed in 3.12, but it only
  got a proper "DeprecationWarning" in 3.12. May be removed in 3.14.
  (Contributed by Nikita Sobolev in gh-101866.)

* "typing": "ByteString", deprecated since Python 3.9, now causes a
  "DeprecationWarning" to be emitted when it is used.

* "urllib.parse.Quoter" is deprecated: it was not intended to be a
  public API. (Contributed by Gregory P. Smith in gh-88168.)

* "xml.etree.ElementTree": Testing the truth value of an "Element" is
  deprecated and will raise an exception in Python 3.14.


Pending Removal in Python 3.15
------------------------------

* "http.server.CGIHTTPRequestHandler" will be removed along with its
  related "--cgi" flag to "python -m http.server".  It was obsolete
  and rarely used.  No direct replacement exists.  *Anything* is
  better than CGI to interface a web server with a request handler.

* "locale": "locale.getdefaultlocale()" was deprecated in Python 3.11
  and originally planned for removal in Python 3.13 (gh-90817), but
  removal has been postponed to Python 3.15. Use "locale.setlocale()",
  "locale.getencoding()" and "locale.getlocale()" instead.
  (Contributed by Hugo van Kemenade in gh-111187.)

* "pathlib": "pathlib.PurePath.is_reserved()" is deprecated and
  scheduled for removal in Python 3.15. Use "os.path.isreserved()" to
  detect reserved paths on Windows.

* "threading": Passing any arguments to "threading.RLock()" is now
  deprecated. C version allows any numbers of args and kwargs, but
  they are just ignored. Python version does not allow any arguments.
  All arguments will be removed from "threading.RLock()" in Python
  3.15. (Contributed by Nikita Sobolev in gh-102029.)

* "typing.NamedTuple":

  * The undocumented keyword argument syntax for creating NamedTuple
    classes ("NT = NamedTuple("NT", x=int)") is deprecated, and will
    be disallowed in 3.15. Use the class-based syntax or the
    functional syntax instead.

  * When using the functional syntax to create a NamedTuple class,
    failing to pass a value to the 'fields' parameter ("NT =
    NamedTuple("NT")") is deprecated. Passing "None" to the 'fields'
    parameter ("NT = NamedTuple("NT", None)") is also deprecated. Both
    will be disallowed in Python 3.15. To create a NamedTuple class
    with 0 fields, use "class NT(NamedTuple): pass" or "NT =
    NamedTuple("NT", [])".

* "typing.TypedDict": When using the functional syntax to create a
  TypedDict class, failing to pass a value to the 'fields' parameter
  ("TD = TypedDict("TD")") is deprecated. Passing "None" to the
  'fields' parameter ("TD = TypedDict("TD", None)") is also
  deprecated. Both will be disallowed in Python 3.15. To create a
  TypedDict class with 0 fields, use "class TD(TypedDict): pass" or
  "TD = TypedDict("TD", {})".

* "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. (Contributed by Victor Stinner in
  gh-105096.)

* "platform.java_ver()" is deprecated and will be removed in 3.15. It
  was largely untested, had a confusing API, and was only useful for
  Jython support. (Contributed by Nikita Sobolev in gh-116349.)


Pending Removal in Python 3.16
------------------------------

* "array.array" "'u'" type ("wchar_t"): use the "'w'" type instead
  ("Py_UCS4").


Pending Removal in Future Versions
----------------------------------

The following APIs were deprecated in earlier Python versions and will
be removed, although there is currently no date scheduled for their
removal.

* "argparse": Nesting argument groups and nesting mutually exclusive
  groups are deprecated.

* "builtins":

  * "~bool", bitwise inversion on bool.

  * "bool(NotImplemented)".

  * Generators: "throw(type, exc, tb)" and "athrow(type, exc, tb)"
    signature is deprecated: use "throw(exc)" and "athrow(exc)"
    instead, the single argument signature.

  * Currently Python accepts numeric literals immediately followed by
    keywords, for example "0in x", "1or x", "0if 1else 2".  It allows
    confusing and ambiguous expressions like "[0x1for x in y]" (which
    can be interpreted as "[0x1 for x in y]" or "[0x1f or x in y]").
    A syntax warning is raised if the numeric literal is immediately
    followed by one of keywords "and", "else", "for", "if", "in", "is"
    and "or".  In a future release it will be changed to a syntax
    error. (gh-87999)

  * Support for "__index__()" and "__int__()" method returning non-int
    type: these methods will be required to return an instance of a
    strict subclass of "int".

  * Support for "__float__()" method returning a strict subclass of
    "float": these methods will be required to return an instance of
    "float".

  * Support for "__complex__()" method returning a strict subclass of
    "complex": these methods will be required to return an instance of
    "complex".

  * Delegation of "int()" to "__trunc__()" method.

* "calendar": "calendar.January" and "calendar.February" constants are
  deprecated and replaced by "calendar.JANUARY" and
  "calendar.FEBRUARY". (Contributed by Prince Roshan in gh-103636.)

* "codeobject.co_lnotab": use the "codeobject.co_lines()" method
  instead.

* "datetime":

  * "utcnow()": use "datetime.datetime.now(tz=datetime.UTC)".

  * "utcfromtimestamp()": use
    "datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC)".

* "gettext": Plural value must be an integer.

* "importlib":

  * "load_module()" method: use "exec_module()" instead.

  * "cache_from_source()" *debug_override* parameter is deprecated:
    use the *optimization* parameter instead.

* "importlib.metadata":

  * "EntryPoints" tuple interface.

  * Implicit "None" on return values.

* "mailbox": Use of StringIO input and text mode is deprecated, use
  BytesIO and binary mode instead.

* "os": Calling "os.register_at_fork()" in multi-threaded process.

* "pydoc.ErrorDuringImport": A tuple value for *exc_info* parameter is
  deprecated, use an exception instance.

* "re": More strict rules are now applied for numerical group
  references and group names in regular expressions.  Only sequence of
  ASCII digits is now accepted as a numerical reference.  The group
  name in bytes patterns and replacement strings can now only contain
  ASCII letters and digits and underscore. (Contributed by Serhiy
  Storchaka in gh-91760.)

* "sre_compile", "sre_constants" and "sre_parse" modules.

* "ssl" options and protocols:

  * "ssl.SSLContext" without protocol argument is deprecated.

  * "ssl.SSLContext": "set_npn_protocols()" and
    "selected_npn_protocol()" are deprecated: use ALPN instead.

  * "ssl.OP_NO_SSL*" options

  * "ssl.OP_NO_TLS*" options

  * "ssl.PROTOCOL_SSLv3"

  * "ssl.PROTOCOL_TLS"

  * "ssl.PROTOCOL_TLSv1"

  * "ssl.PROTOCOL_TLSv1_1"

  * "ssl.PROTOCOL_TLSv1_2"

  * "ssl.TLSVersion.SSLv3"

  * "ssl.TLSVersion.TLSv1"

  * "ssl.TLSVersion.TLSv1_1"

* "sysconfig.is_python_build()" *check_home* parameter is deprecated
  and ignored.

* "threading" methods:

  * "threading.Condition.notifyAll()": use "notify_all()".

  * "threading.Event.isSet()": use "is_set()".

  * "threading.Thread.isDaemon()", "threading.Thread.setDaemon()": use
    "threading.Thread.daemon" attribute.

  * "threading.Thread.getName()", "threading.Thread.setName()": use
    "threading.Thread.name" attribute.

  * "threading.currentThread()": use "threading.current_thread()".

  * "threading.activeCount()": use "threading.active_count()".

* "typing.Text" (gh-92332).

* "unittest.IsolatedAsyncioTestCase": it is deprecated to return a
  value that is not "None" from a test case.

* "urllib.parse" deprecated functions: "urlparse()" instead

  * "splitattr()"

  * "splithost()"

  * "splitnport()"

  * "splitpasswd()"

  * "splitport()"

  * "splitquery()"

  * "splittag()"

  * "splittype()"

  * "splituser()"

  * "splitvalue()"

  * "to_bytes()"

* "urllib.request": "URLopener" and "FancyURLopener" style of invoking
  requests is deprecated. Use newer "urlopen()" functions and methods.

* "wsgiref": "SimpleHandler.stdout.write()" should not do partial
  writes.

* "zipimport.zipimporter.load_module()" is deprecated: use
  "exec_module()" instead.


Removed
=======


PEP 594: dead batteries
-----------------------

* **PEP 594** removed 19 modules from the standard library, deprecated
  in Python 3.11:

  * "aifc". (Contributed by Victor Stinner in gh-104773.)

  * "audioop". (Contributed by Victor Stinner in gh-104773.)

  * "chunk". (Contributed by Victor Stinner in gh-104773.)

  * "cgi" and "cgitb".

    * "cgi.FieldStorage" can typically be replaced with
      "urllib.parse.parse_qsl()" for "GET" and "HEAD" requests, and
      the "email.message" module or multipart PyPI project for "POST"
      and "PUT".

    * "cgi.parse()" can be replaced by calling
      "urllib.parse.parse_qs()" directly on the desired query string,
      except for "multipart/form-data" input, which can be handled as
      described for "cgi.parse_multipart()".

    * "cgi.parse_header()" can be replaced with the functionality in
      the "email" package, which implements the same MIME RFCs. For
      example, with "email.message.EmailMessage":

         from email.message import EmailMessage
         msg = EmailMessage()
         msg['content-type'] = 'application/json; charset="utf8"'
         main, params = msg.get_content_type(), msg['content-type'].params

    * "cgi.parse_multipart()" can be replaced with the functionality
      in the "email" package (e.g. "email.message.EmailMessage" and
      "email.message.Message") which implements the same MIME RFCs, or
      with the multipart PyPI project.

    (Contributed by Victor Stinner in gh-104773.)

  * "crypt" module and its private "_crypt" extension. The "hashlib"
    module is a potential replacement for certain use cases.
    Otherwise, the following PyPI projects can be used:

    * bcrypt: Modern password hashing for your software and your
      servers.

    * passlib: Comprehensive password hashing framework supporting
      over 30 schemes.

    * argon2-cffi: The secure Argon2 password hashing algorithm.

    * legacycrypt: Wrapper to the POSIX crypt library call and
      associated functionality.

    (Contributed by Victor Stinner in gh-104773.)

  * "imghdr": use the projects filetype, puremagic, or python-magic
    instead. (Contributed by Victor Stinner in gh-104773.)

  * "mailcap". The "mimetypes" module provides an alternative.
    (Contributed by Victor Stinner in gh-104773.)

  * "msilib". (Contributed by Zachary Ware in gh-104773.)

  * "nis". (Contributed by Victor Stinner in gh-104773.)

  * "nntplib": the PyPI nntplib project can be used instead.
    (Contributed by Victor Stinner in gh-104773.)

  * "ossaudiodev": use the pygame project for audio playback.
    (Contributed by Victor Stinner in gh-104780.)

  * "pipes": use the "subprocess" module instead. (Contributed by
    Victor Stinner in gh-104773.)

  * "sndhdr": use the projects filetype, puremagic, or python-magic
    instead. (Contributed by Victor Stinner in gh-104773.)

  * "spwd": the python-pam project can be used instead. (Contributed
    by Victor Stinner in gh-104773.)

  * "sunau". (Contributed by Victor Stinner in gh-104773.)

  * "telnetlib", use the projects telnetlib3 or Exscript instead.
    (Contributed by Victor Stinner in gh-104773.)

  * "uu": the "base64" module is a modern alternative. (Contributed by
    Victor Stinner in gh-104773.)

  * "xdrlib". (Contributed by Victor Stinner in gh-104773.)


2to3
----

* Remove the "2to3" program and the "lib2to3" module, deprecated in
  Python 3.11. (Contributed by Victor Stinner in gh-104780.)


configparser
------------

* Remove the undocumented "configparser.LegacyInterpolation" class,
  deprecated in the docstring since Python 3.2, and with a deprecation
  warning since Python 3.11. (Contributed by Hugo van Kemenade in
  gh-104886.)


importlib
---------

* Remove deprecated "__getitem__()" access for
  "importlib.metadata.EntryPoint" objects. (Contributed by Jason R.
  Coombs in gh-113175.)


locale
------

* Remove "locale.resetlocale()" function deprecated in Python 3.11:
  use "locale.setlocale(locale.LC_ALL, "")" instead. (Contributed by
  Victor Stinner in gh-104783.)


logging
-------

* "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. (Contributed by Victor
  Stinner in gh-105376.)


pathlib
-------

* Remove support for using "pathlib.Path" objects as context managers.
  This functionality was deprecated and made a no-op in Python 3.9.


re
--

* Remove undocumented, never working, and deprecated "re.template"
  function and "re.TEMPLATE" flag (and "re.T" alias). (Contributed by
  Serhiy Storchaka and Nikita Sobolev in gh-105687.)


tkinter
-------

* Remove the "tkinter.tix" module, deprecated in Python 3.6.  The
  third-party Tix library which the module wrapped is unmaintained.
  (Contributed by Zachary Ware in gh-75552.)


turtle
------

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


typing
------

* Namespaces "typing.io" and "typing.re", deprecated in Python 3.8,
  are now removed. The items in those namespaces can be imported
  directly from "typing". (Contributed by Sebastian Rittau in
  gh-92871.)

* Remove support for the keyword-argument method of creating
  "typing.TypedDict" types, deprecated in Python 3.11. (Contributed by
  Tomas Roun in gh-104786.)


unittest
--------

* Removed the following "unittest" functions, deprecated in Python
  3.11:

  * "unittest.findTestCases()"

  * "unittest.makeSuite()"

  * "unittest.getTestCaseNames()"

  Use "TestLoader" methods instead:

  * "unittest.TestLoader.loadTestsFromModule()"

  * "unittest.TestLoader.loadTestsFromTestCase()"

  * "unittest.TestLoader.getTestCaseNames()"

  (Contributed by Hugo van Kemenade in gh-104835.)

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


urllib
------

* Remove *cafile*, *capath* and *cadefault* parameters of the
  "urllib.request.urlopen()" function, deprecated in Python 3.6: use
  the *context* parameter instead. Please use
  "ssl.SSLContext.load_cert_chain()" instead, or let
  "ssl.create_default_context()" select the system's trusted CA
  certificates for you. (Contributed by Victor Stinner in gh-105382.)


webbrowser
----------

* Remove the untested and undocumented "webbrowser" "MacOSX" class,
  deprecated in Python 3.11. Use the "MacOSXOSAScript" class
  (introduced in Python 3.2) instead. (Contributed by Hugo van
  Kemenade in gh-104804.)

* Remove deprecated "webbrowser.MacOSXOSAScript._name" attribute. Use
  "webbrowser.MacOSXOSAScript.name" attribute instead. (Contributed by
  Nikita Sobolev in gh-105546.)


Others
------

* None yet


CPython bytecode changes
========================

* The oparg of "YIELD_VALUE" is now "1" if the yield is part of a
  yield-from or await, and "0" otherwise. The oparg of "RESUME" was
  changed to add a bit indicating whether the except-depth is 1, which
  is needed to optimize closing of generators. (Contributed by Irit
  Katriel in gh-111354.)


Porting to Python 3.13
======================

This section lists previously described changes and other bugfixes
that may require changes to your code.


Changes in the Python API
-------------------------

* Functions "PyDict_GetItem()", "PyDict_GetItemString()",
  "PyMapping_HasKey()", "PyMapping_HasKeyString()",
  "PyObject_HasAttr()", "PyObject_HasAttrString()", and
  "PySys_GetObject()", which clear all errors which occurred when
  calling them, now report them using "sys.unraisablehook()". You may
  replace them with other functions as recommended in the
  documentation. (Contributed by Serhiy Storchaka in gh-106672.)

* An "OSError" is now raised by "getpass.getuser()" for any failure to
  retrieve a username, instead of "ImportError" on non-Unix platforms
  or "KeyError" on Unix platforms where the password database is
  empty.

* The "threading" module now expects the "_thread" module to have an
  "_is_main_interpreter" attribute.  It is a function with no
  arguments that return "True" if the current interpreter is the main
  interpreter.

  Any library or application that provides a custom "_thread" module
  must provide "_is_main_interpreter()", just like the module's other
  "private" attributes. (See gh-112826.)

* "mailbox.Maildir" now ignores files with a leading dot. (Contributed
  by Zackery Spytz in gh-65559.)

* "pathlib.Path.glob()" and "rglob()" now return both files and
  directories if a pattern that ends with ""**"" is given, rather than
  directories only. Users may add a trailing slash to match only
  directories.

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


Build Changes
=============

* Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate the
  "configure" script. (Contributed by Christian Heimes in gh-89886.)

* SQLite 3.15.2 or newer is required to build the "sqlite3" extension
  module. (Contributed by Erlend Aasland in gh-105875.)

* Python built with "configure" "--with-trace-refs" (tracing
  references) is now ABI compatible with the Python release build and
  debug build. (Contributed by Victor Stinner in gh-108634.)

* Building CPython now requires a compiler with support for the C11
  atomic library, GCC built-in atomic functions, or MSVC interlocked
  intrinsics.

* The "errno", "fcntl", "grp", "md5", "pwd", "resource", "termios",
  "winsound", "_ctypes_test", "_multiprocessing.posixshmem",
  "_scproxy", "_stat", "_statistics", "_testconsole",
  "_testimportmultiple" and "_uuid" C extensions are now built with
  the limited C API. (Contributed by Victor Stinner in gh-85283.)

* "wasm32-wasi" is now a tier 2 platform. (Contributed by Brett Cannon
  in gh-115192.)

* "wasm32-emscripten" is no longer a supported platform. (Contributed
  by Brett Cannon in gh-115192.)


C API Changes
=============


New Features
------------

* You no longer have to define the "PY_SSIZE_T_CLEAN" macro before
  including "Python.h" when using "#" formats in format codes. APIs
  accepting the format codes always use "Py_ssize_t" for "#" formats.
  (Contributed by Inada Naoki in gh-104922.)

* The *keywords* parameter of "PyArg_ParseTupleAndKeywords()" and
  "PyArg_VaParseTupleAndKeywords()" now has type char *const* in C and
  const char *const* in C++, instead of char**. It makes these
  functions compatible with arguments of type const char *const*,
  const char** or char *const* in C++ and char *const* in C without an
  explicit type cast. This can be overridden with the "PY_CXX_CONST"
  macro. (Contributed by Serhiy Storchaka in gh-65210.)

* Add "PyImport_AddModuleRef()": similar to "PyImport_AddModule()",
  but return a *strong reference* instead of a *borrowed reference*.
  (Contributed by Victor Stinner in gh-105922.)

* Add "PyWeakref_GetRef()" function: similar to
  "PyWeakref_GetObject()" but returns a *strong reference*, or "NULL"
  if the referent is no longer live. (Contributed by Victor Stinner in
  gh-105927.)

* Add "PyObject_GetOptionalAttr()" and
  "PyObject_GetOptionalAttrString()", variants of "PyObject_GetAttr()"
  and "PyObject_GetAttrString()" which don't raise "AttributeError" if
  the attribute is not found. These variants are more convenient and
  faster if the missing attribute should not be treated as a failure.
  (Contributed by Serhiy Storchaka in gh-106521.)

* Add "PyMapping_GetOptionalItem()" and
  "PyMapping_GetOptionalItemString()": variants of
  "PyObject_GetItem()" and "PyMapping_GetItemString()" which don't
  raise "KeyError" if the key is not found. These variants are more
  convenient and faster if the missing key should not be treated as a
  failure. (Contributed by Serhiy Storchaka in gh-106307.)

* Add fixed variants of functions which silently ignore errors:

  * "PyObject_HasAttrWithError()" replaces "PyObject_HasAttr()".

  * "PyObject_HasAttrStringWithError()" replaces
    "PyObject_HasAttrString()".

  * "PyMapping_HasKeyWithError()" replaces "PyMapping_HasKey()".

  * "PyMapping_HasKeyStringWithError()" replaces
    "PyMapping_HasKeyString()".

  New functions return not only "1" for true and "0" for false, but
  also "-1" for error.

  (Contributed by Serhiy Storchaka in gh-108511.)

* If Python is built in debug mode or "with assertions",
  "PyTuple_SET_ITEM()" and "PyList_SET_ITEM()" now check the index
  argument with an assertion. (Contributed by Victor Stinner in
  gh-106168.)

* Add "PyModule_Add()" function: similar to "PyModule_AddObjectRef()"
  and "PyModule_AddObject()" but always steals a reference to the
  value. (Contributed by Serhiy Storchaka in gh-86493.)

* Add "PyDict_GetItemRef()" and "PyDict_GetItemStringRef()" functions:
  similar to "PyDict_GetItemWithError()" but returning a *strong
  reference* instead of a *borrowed reference*. Moreover, these
  functions return -1 on error and so checking "PyErr_Occurred()" is
  not needed. (Contributed by Victor Stinner in gh-106004.)

* Added "PyDict_SetDefaultRef()", which is similar to
  "PyDict_SetDefault()" but returns a *strong reference* instead of a
  *borrowed reference*. This function returns "-1" on error, "0" on
  insertion, and "1" if the key was already present in the dictionary.
  (Contributed by Sam Gross in gh-112066.)

* Add "PyDict_ContainsString()" function: same as "PyDict_Contains()",
  but *key* is specified as a const char* UTF-8 encoded bytes string,
  rather than a PyObject*. (Contributed by Victor Stinner in
  gh-108314.)

* Added "PyList_GetItemRef()" function: similar to "PyList_GetItem()"
  but returns a *strong reference* instead of a *borrowed reference*.

* Add "Py_IsFinalizing()" function: check if the main Python
  interpreter is *shutting down*. (Contributed by Victor Stinner in
  gh-108014.)

* Add "PyLong_AsInt()" function: similar to "PyLong_AsLong()", but
  store the result in a C int instead of a C long. Previously, it was
  known as the private function "_PyLong_AsInt()" (with an underscore
  prefix). (Contributed by Victor Stinner in gh-108014.)

* Python built with "configure" "--with-trace-refs" (tracing
  references) now supports the Limited API. (Contributed by Victor
  Stinner in gh-108634.)

* Add "PyObject_VisitManagedDict()" and "PyObject_ClearManagedDict()"
  functions which must be called by the traverse and clear functions
  of a type using "Py_TPFLAGS_MANAGED_DICT" flag.  The pythoncapi-
  compat project can be used to get these functions on Python 3.11 and
  3.12. (Contributed by Victor Stinner in gh-107073.)

* Add "PyUnicode_EqualToUTF8AndSize()" and "PyUnicode_EqualToUTF8()"
  functions: compare Unicode object with a const char* UTF-8 encoded
  string and return true ("1") if they are equal, or false ("0")
  otherwise. These functions do not raise exceptions. (Contributed by
  Serhiy Storchaka in gh-110289.)

* Add "PyThreadState_GetUnchecked()" function: similar to
  "PyThreadState_Get()", but don't kill the process with a fatal error
  if it is NULL. The caller is responsible to check if the result is
  NULL. Previously, the function was private and known as
  "_PyThreadState_UncheckedGet()". (Contributed by Victor Stinner in
  gh-108867.)

* Add "PySys_AuditTuple()" function: similar to "PySys_Audit()", but
  pass event arguments as a Python "tuple" object. (Contributed by
  Victor Stinner in gh-85283.)

* "PyArg_ParseTupleAndKeywords()" now supports non-ASCII keyword
  parameter names. (Contributed by Serhiy Storchaka in gh-110815.)

* Add "PyMem_RawMalloc()", "PyMem_RawCalloc()", "PyMem_RawRealloc()"
  and "PyMem_RawFree()" to the limited C API (version 3.13).
  (Contributed by Victor Stinner in gh-85283.)

* Add "PySys_Audit()" and "PySys_AuditTuple()" functions to the
  limited C API. (Contributed by Victor Stinner in gh-85283.)

* Add "PyErr_FormatUnraisable()" function: similar to
  "PyErr_WriteUnraisable()", but allow customizing the warning
  message. (Contributed by Serhiy Storchaka in gh-108082.)

* Add "PyList_Extend()" and "PyList_Clear()" functions: similar to
  Python "list.extend()" and "list.clear()" methods. (Contributed by
  Victor Stinner in gh-111138.)

* 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 is missing. (Contributed by Stefan
  Behnel and Victor Stinner in gh-111262.)

* Add "Py_HashPointer()" function to hash a pointer. (Contributed by
  Victor Stinner in gh-111545.)

* Add "PyObject_GenericHash()" function that implements the default
  hashing function of a Python object. (Contributed by Serhiy
  Storchaka in gh-113024.)

* Add PyTime C API:

  * "PyTime_t" type.

  * "PyTime_MIN" and "PyTime_MAX" constants.

  * "PyTime_AsSecondsDouble()" "PyTime_Monotonic()",
    "PyTime_PerfCounter()", and "PyTime_Time()" functions.

  (Contributed by Victor Stinner and Petr Viktorin in gh-110850.)

* Add "PyLong_AsNativeBytes()", "PyLong_FromNativeBytes()" and
  "PyLong_FromUnsignedNativeBytes()" functions to simplify converting
  between native integer types and Python "int" objects. (Contributed
  by Steve Dower in gh-111140.)

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

* Add "PyType_GetModuleName()" function to get the type's module name.
  Equivalent to getting the "type.__module__" attribute. (Contributed
  by Eric Snow and Victor Stinner in gh-111696.)

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

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

* Add "PyType_GetModuleByDef()" to the limited C API (Contributed by
  Victor Stinner in gh-116936.)


Porting to Python 3.13
----------------------

* "Python.h" no longer includes the "<ieeefp.h>" standard header. It
  was included for the "finite()" function which is now provided by
  the "<math.h>" header. It should now be included explicitly if
  needed. Remove also the "HAVE_IEEEFP_H" macro. (Contributed by
  Victor Stinner in gh-108765.)

* "Python.h" no longer includes these standard header files:
  "<time.h>", "<sys/select.h>" and "<sys/time.h>". If needed, they
  should now be included explicitly. For example, "<time.h>" provides
  the "clock()" and "gmtime()" functions, "<sys/select.h>" provides
  the "select()" function, and "<sys/time.h>" provides the
  "futimes()", "gettimeofday()" and "setitimer()" functions.
  (Contributed by Victor Stinner in gh-108765.)

* If the "Py_LIMITED_API" macro is defined, "Py_BUILD_CORE",
  "Py_BUILD_CORE_BUILTIN" and "Py_BUILD_CORE_MODULE" macros are now
  undefined by "<Python.h>". (Contributed by Victor Stinner in
  gh-85283.)

* The old trashcan macros "Py_TRASHCAN_SAFE_BEGIN" and
  "Py_TRASHCAN_SAFE_END" were removed. They should be replaced by the
  new macros "Py_TRASHCAN_BEGIN" and "Py_TRASHCAN_END".

  A tp_dealloc function that has the old macros, such as:

     static void
     mytype_dealloc(mytype *p)
     {
         PyObject_GC_UnTrack(p);
         Py_TRASHCAN_SAFE_BEGIN(p);
         ...
         Py_TRASHCAN_SAFE_END
     }

  should migrate to the new macros as follows:

     static void
     mytype_dealloc(mytype *p)
     {
         PyObject_GC_UnTrack(p);
         Py_TRASHCAN_BEGIN(p, mytype_dealloc)
         ...
         Py_TRASHCAN_END
     }

  Note that "Py_TRASHCAN_BEGIN" has a second argument which should be
  the deallocation function it is in.

* On Windows, "Python.h" no longer includes the "<stddef.h>" standard
  header file. If needed, it should now be included explicitly. For
  example, it provides "offsetof()" function, and "size_t" and
  "ptrdiff_t" types. Including "<stddef.h>" explicitly was already
  needed by all other platforms, the "HAVE_STDDEF_H" macro is only
  defined on Windows. (Contributed by Victor Stinner in gh-108765.)


Deprecated
----------

* Passing optional arguments *maxsplit*, *count* and *flags* in
  module-level functions "re.split()", "re.sub()" and "re.subn()" as
  positional arguments is now deprecated. In future Python versions
  these parameters will be keyword-only. (Contributed by Serhiy
  Storchaka in gh-56166.)

* Deprecate the old "Py_UNICODE" and "PY_UNICODE_TYPE" types: use
  directly the "wchar_t" type instead. Since Python 3.3, "Py_UNICODE"
  and "PY_UNICODE_TYPE" are just aliases to "wchar_t". (Contributed by
  Victor Stinner in gh-105156.)

* Deprecate old Python initialization functions:

  * "PySys_ResetWarnOptions()": clear "sys.warnoptions" and
    "warnings.filters" instead.

  * "Py_GetExecPrefix()": get "sys.exec_prefix" instead.

  * "Py_GetPath()": get "sys.path" instead.

  * "Py_GetPrefix()": get "sys.prefix" instead.

  * "Py_GetProgramFullPath()": get "sys.executable" instead.

  * "Py_GetProgramName()": get "sys.executable" instead.

  * "Py_GetPythonHome()": get "PyConfig.home" or "PYTHONHOME"
    environment variable instead.

  Functions scheduled for removal in Python 3.15. (Contributed by
  Victor Stinner in gh-105145.)

* Deprecate the "PyImport_ImportModuleNoBlock()" function which is
  just an alias to "PyImport_ImportModule()" since Python 3.3.
  Scheduled for removal in Python 3.15. (Contributed by Victor Stinner
  in gh-105396.)

* Deprecate the "PyWeakref_GetObject()" and "PyWeakref_GET_OBJECT()"
  functions, which return a *borrowed reference*: use the new
  "PyWeakref_GetRef()" function instead, it returns a *strong
  reference*. The pythoncapi-compat project can be used to get
  "PyWeakref_GetRef()" on Python 3.12 and older. (Contributed by
  Victor Stinner in gh-105927.)


Removed
-------

* Removed chained "classmethod" descriptors (introduced in gh-63272).
  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.  (Contributed by Raymond Hettinger in gh-89519.)

* Remove many APIs (functions, macros, variables) with names prefixed
  by "_Py" or "_PY" (considered as private API). If your project is
  affected by one of these removals and you consider that the removed
  API should remain available, please open a new issue to request a
  public C API and add "cc @vstinner" to the issue to notify Victor
  Stinner. (Contributed by Victor Stinner in gh-106320.)

* Remove functions deprecated in Python 3.9:

  * "PyEval_CallObject()", "PyEval_CallObjectWithKeywords()": use
    "PyObject_CallNoArgs()" or "PyObject_Call()" instead. Warning:
    "PyObject_Call()" positional arguments must be a "tuple" and must
    not be "NULL", keyword arguments must be a "dict" or "NULL",
    whereas removed functions checked arguments type and accepted
    "NULL" positional and keyword arguments. To replace
    "PyEval_CallObjectWithKeywords(func, NULL, kwargs)" with
    "PyObject_Call()", pass an empty tuple as positional arguments
    using "PyTuple_New(0)".

  * "PyEval_CallFunction()": use "PyObject_CallFunction()" instead.

  * "PyEval_CallMethod()": use "PyObject_CallMethod()" instead.

  * "PyCFunction_Call()": use "PyObject_Call()" instead.

  (Contributed by Victor Stinner in gh-105107.)

* Remove old buffer protocols deprecated in Python 3.0. Use バッファプ
  ロトコル (buffer Protocol) instead.

  * "PyObject_CheckReadBuffer()": Use "PyObject_CheckBuffer()" to test
    if the object supports the buffer protocol. Note that
    "PyObject_CheckBuffer()" doesn't guarantee that
    "PyObject_GetBuffer()" will succeed. To test if the object is
    actually readable, see the next example of "PyObject_GetBuffer()".

  * "PyObject_AsCharBuffer()", "PyObject_AsReadBuffer()":
    "PyObject_GetBuffer()" and "PyBuffer_Release()" instead:

       Py_buffer view;
       if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) < 0) {
           return NULL;
       }
       // Use `view.buf` and `view.len` to read from the buffer.
       // You may need to cast buf as `(const char*)view.buf`.
       PyBuffer_Release(&view);

  * "PyObject_AsWriteBuffer()": Use "PyObject_GetBuffer()" and
    "PyBuffer_Release()" instead:

       Py_buffer view;
       if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) < 0) {
           return NULL;
       }
       // Use `view.buf` and `view.len` to write to the buffer.
       PyBuffer_Release(&view);

  (Contributed by Inada Naoki in gh-85275.)

* Remove the following old functions to configure the Python
  initialization, deprecated in Python 3.11:

  * "PySys_AddWarnOptionUnicode()": use "PyConfig.warnoptions"
    instead.

  * "PySys_AddWarnOption()": use "PyConfig.warnoptions" instead.

  * "PySys_AddXOption()": use "PyConfig.xoptions" instead.

  * "PySys_HasWarnOptions()": use "PyConfig.xoptions" instead.

  * "PySys_SetArgvEx()": set "PyConfig.argv" instead.

  * "PySys_SetArgv()": set "PyConfig.argv" instead.

  * "PySys_SetPath()": set "PyConfig.module_search_paths" instead.

  * "Py_SetPath()": set "PyConfig.module_search_paths" instead.

  * "Py_SetProgramName()": set "PyConfig.program_name" instead.

  * "Py_SetPythonHome()": set "PyConfig.home" instead.

  * "Py_SetStandardStreamEncoding()": set "PyConfig.stdio_encoding"
    instead, and set also maybe "PyConfig.legacy_windows_stdio" (on
    Windows).

  * "_Py_SetProgramFullPath()": set "PyConfig.executable" instead.

  Use the new "PyConfig" API of the Python Initialization
  Configuration instead (**PEP 587**), added to Python 3.8.
  (Contributed by Victor Stinner in gh-105145.)

* 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".  The new macros were
  added in Python 3.8 and the old macros were deprecated in Python
  3.11. (Contributed by Irit Katriel in gh-105111.)

* Remove "PyEval_InitThreads()" and "PyEval_ThreadsInitialized()"
  functions, deprecated in Python 3.9. Since Python 3.7,
  "Py_Initialize()" always creates the GIL: calling
  "PyEval_InitThreads()" did nothing and "PyEval_ThreadsInitialized()"
  always returned non-zero. (Contributed by Victor Stinner in
  gh-105182.)

* Remove "PyEval_AcquireLock()" and "PyEval_ReleaseLock()" functions,
  deprecated in Python 3.2. They didn't update the current thread
  state. They can be replaced with:

  * "PyEval_SaveThread()" and "PyEval_RestoreThread()";

  * low-level "PyEval_AcquireThread()" and "PyEval_RestoreThread()";

  * or "PyGILState_Ensure()" and "PyGILState_Release()".

  (Contributed by Victor Stinner in gh-105182.)

* Remove "cpython/pytime.h" header file: it only contained private
  functions. (Contributed by Victor Stinner in gh-106316.)

* Remove "_PyInterpreterState_Get()" alias to
  "PyInterpreterState_Get()" which was kept for backward compatibility
  with Python 3.8. The pythoncapi-compat project can be used to get
  "PyInterpreterState_Get()" on Python 3.8 and older. (Contributed by
  Victor Stinner in gh-106320.)

* The "PyModule_AddObject()" function is now *soft deprecated*:
  "PyModule_Add()" or "PyModule_AddObjectRef()" functions should be
  used instead. (Contributed by Serhiy Storchaka in gh-86493.)


Pending Removal in Python 3.14
------------------------------

* Creating immutable types ("Py_TPFLAGS_IMMUTABLETYPE") with mutable
  bases using the C API.

* Global configuration variables:

  * "Py_DebugFlag": use "PyConfig.parser_debug"

  * "Py_VerboseFlag": use "PyConfig.verbose"

  * "Py_QuietFlag": use "PyConfig.quiet"

  * "Py_InteractiveFlag": use "PyConfig.interactive"

  * "Py_InspectFlag": use "PyConfig.inspect"

  * "Py_OptimizeFlag": use "PyConfig.optimization_level"

  * "Py_NoSiteFlag": use "PyConfig.site_import"

  * "Py_BytesWarningFlag": use "PyConfig.bytes_warning"

  * "Py_FrozenFlag": use "PyConfig.pathconfig_warnings"

  * "Py_IgnoreEnvironmentFlag": use "PyConfig.use_environment"

  * "Py_DontWriteBytecodeFlag": use "PyConfig.write_bytecode"

  * "Py_NoUserSiteDirectory": use "PyConfig.user_site_directory"

  * "Py_UnbufferedStdioFlag": use "PyConfig.buffered_stdio"

  * "Py_HashRandomizationFlag": use "PyConfig.use_hash_seed" and
    "PyConfig.hash_seed"

  * "Py_IsolatedFlag": use "PyConfig.isolated"

  * "Py_LegacyWindowsFSEncodingFlag": use
    "PyPreConfig.legacy_windows_fs_encoding"

  * "Py_LegacyWindowsStdioFlag": use "PyConfig.legacy_windows_stdio"

  * "Py_FileSystemDefaultEncoding": use "PyConfig.filesystem_encoding"

  * "Py_HasFileSystemDefaultEncoding": use
    "PyConfig.filesystem_encoding"

  * "Py_FileSystemDefaultEncodeErrors": use
    "PyConfig.filesystem_errors"

  * "Py_UTF8Mode": use "PyPreConfig.utf8_mode" (see
    "Py_PreInitialize()")

  The "Py_InitializeFromConfig()" API should be used with "PyConfig"
  instead.


Pending Removal in Python 3.15
------------------------------

* "PyImport_ImportModuleNoBlock()": use "PyImport_ImportModule()".

* "PyWeakref_GET_OBJECT()": use "PyWeakref_GetRef()" instead.

* "PyWeakref_GetObject()": use "PyWeakref_GetRef()" instead.

* "Py_UNICODE_WIDE" type: use "wchar_t" instead.

* "Py_UNICODE" type: use "wchar_t" instead.

* Python initialization functions:

  * "PySys_ResetWarnOptions()": clear "sys.warnoptions" and
    "warnings.filters" instead.

  * "Py_GetExecPrefix()": get "sys.exec_prefix" instead.

  * "Py_GetPath()": get "sys.path" instead.

  * "Py_GetPrefix()": get "sys.prefix" instead.

  * "Py_GetProgramFullPath()": get "sys.executable" instead.

  * "Py_GetProgramName()": get "sys.executable" instead.

  * "Py_GetPythonHome()": get "PyConfig.home" or "PYTHONHOME"
    environment variable instead.


Pending Removal in Future Versions
----------------------------------

The following APIs were deprecated in earlier Python versions and will
be removed, although there is currently no date scheduled for their
removal.

* "Py_TPFLAGS_HAVE_FINALIZE": no needed since Python 3.8.

* "PyErr_Fetch()": use "PyErr_GetRaisedException()".

* "PyErr_NormalizeException()": use "PyErr_GetRaisedException()".

* "PyErr_Restore()": use "PyErr_SetRaisedException()".

* "PyModule_GetFilename()": use "PyModule_GetFilenameObject()".

* "PyOS_AfterFork()": use "PyOS_AfterFork_Child()".

* "PySlice_GetIndicesEx()".

* "PyUnicode_AsDecodedObject()".

* "PyUnicode_AsDecodedUnicode()".

* "PyUnicode_AsEncodedObject()".

* "PyUnicode_AsEncodedUnicode()".

* "PyUnicode_READY()": not needed since Python 3.12.

* "_PyErr_ChainExceptions()".

* "PyBytesObject.ob_shash" member: call "PyObject_Hash()" instead.

* "PyDictObject.ma_version_tag" member.

* TLS API:

  * "PyThread_create_key()": use "PyThread_tss_alloc()".

  * "PyThread_delete_key()": use "PyThread_tss_free()".

  * "PyThread_set_key_value()": use "PyThread_tss_set()".

  * "PyThread_get_key_value()": use "PyThread_tss_get()".

  * "PyThread_delete_key_value()": use "PyThread_tss_delete()".

  * "PyThread_ReInitTLS()": no longer needed.

* Remove undocumented "PY_TIMEOUT_MAX" constant from the limited C
  API. (Contributed by Victor Stinner in gh-110014.)


Regression Test Changes
=======================

* Python built with "configure" "--with-pydebug" now supports a "-X
  presite=package.module" command-line option. If used, it specifies a
  module that should be imported early in the lifecycle of the
  interpreter, before "site.py" is executed. (Contributed by Łukasz
  Langa in gh-110769.)
