Deprecations
************


Pending removal in Python 3.16
==============================

* The import system:

  * Setting "__loader__" on a module while failing to set
    "__spec__.loader" is deprecated. In Python 3.16, "__loader__" will
    cease to be set or taken into consideration by the import system
    or the standard library.

* "array":

  * The "'u'" format code ("wchar_t") has been deprecated in
    documentation since Python 3.3 and at runtime since Python 3.13.
    Use the "'w'" format code ("Py_UCS4") for Unicode characters
    instead.

* "asyncio":

  * "asyncio.iscoroutinefunction()" is deprecated and will be removed
    in Python 3.16; use "inspect.iscoroutinefunction()" instead.
    (Contributed by Jiahao Li and Kumar Aditya in gh-122875.)

  * "asyncio" policy system is deprecated and will be removed in
    Python 3.16. In particular, the following classes and functions
    are deprecated:

    * "asyncio.AbstractEventLoopPolicy"

    * "asyncio.DefaultEventLoopPolicy"

    * "asyncio.WindowsSelectorEventLoopPolicy"

    * "asyncio.WindowsProactorEventLoopPolicy"

    * "asyncio.get_event_loop_policy()"

    * "asyncio.set_event_loop_policy()"

    Users should use "asyncio.run()" or "asyncio.Runner" with
    *loop_factory* to use the desired event loop implementation.

    For example, to use "asyncio.SelectorEventLoop" on Windows:

       import asyncio

       async def main():
           ...

       asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop)

    (Contributed by Kumar Aditya in gh-127949.)

* "builtins":

  * Bitwise inversion on boolean types, "~True" or "~False" has been
    deprecated since Python 3.12, as it produces surprising and
    unintuitive results ("-2" and "-1"). Use "not x" instead for the
    logical negation of a Boolean. In the rare case that you need the
    bitwise inversion of the underlying integer, convert to "int"
    explicitly ("~int(x)").

* "functools":

  * Calling the Python implementation of "functools.reduce()" with
    *function* or *sequence* as keyword arguments has been deprecated
    since Python 3.14.

* "logging":

  * Support for custom logging handlers with the *strm* argument is
    deprecated and scheduled for removal in Python 3.16. Define
    handlers with the *stream* argument instead. (Contributed by
    Mariusz Felisiak in gh-115032.)

* "mimetypes":

  * Valid extensions start with a ‘.’ or are empty for
    "mimetypes.MimeTypes.add_type()". Undotted extensions are
    deprecated and will raise a "ValueError" in Python 3.16.
    (Contributed by Hugo van Kemenade in gh-75223.)

* "shutil":

  * The "ExecError" exception has been deprecated since Python 3.14.
    It has not been used by any function in "shutil" since Python 3.4,
    and is now an alias of "RuntimeError".

* "symtable":

  * The "Class.get_methods" method has been deprecated since Python
    3.14.

* "sys":

  * The "_enablelegacywindowsfsencoding()" function has been
    deprecated since Python 3.13. Use the
    "PYTHONLEGACYWINDOWSFSENCODING" environment variable instead.

* "sysconfig":

  * The "sysconfig.expand_makefile_vars()" function has been
    deprecated since Python 3.14. Use the "vars" argument of
    "sysconfig.get_paths()" instead.

* "tarfile":

  * The undocumented and unused "TarFile.tarfile" attribute has been
    deprecated since Python 3.13.


Pending removal in Python 3.17
==============================

* "datetime":

  * "strptime()" calls using a format string containing "%e" (day of
    month) without a year. This has been deprecated since Python 3.15.
    (Contributed by Stan Ulbrych in gh-70647.)

* "collections.abc":

  * "collections.abc.ByteString" is scheduled for removal in Python
    3.17.

    Use "isinstance(obj, collections.abc.Buffer)" to test if "obj"
    implements the buffer protocol at runtime. For use in type
    annotations, either use "Buffer" or a union that explicitly
    specifies the types your code supports (e.g., "bytes | bytearray |
    memoryview").

    "ByteString" was originally intended to be an abstract class that
    would serve as a supertype of both "bytes" and "bytearray".
    However, since the ABC never had any methods, knowing that an
    object was an instance of "ByteString" never actually told you
    anything useful about the object. Other common buffer types such
    as "memoryview" were also never understood as subtypes of
    "ByteString" (either at runtime or by static type checkers).

    See **PEP 688** for more details. (Contributed by Shantanu Jain in
    gh-91896.)

* "encodings":

  * Passing non-ascii *encoding* names to
    "encodings.normalize_encoding()" is deprecated and scheduled for
    removal in Python 3.17. (Contributed by Stan Ulbrych in
    gh-136702.)

* "profile":

  * The "profile" module is deprecated and will be removed in Python
    3.17. Use "profiling.tracing" instead, which provides a compatible
    API. See **PEP 799** for details. (Contributed by Pablo Galindo
    and László Kiss Kollár in gh-138122.)

* "webbrowser":

  * "webbrowser.MacOSXOSAScript" is deprecated in favour of
    "webbrowser.MacOS". (gh-137586)

* "typing":

  * Before Python 3.14, old-style unions were implemented using the
    private class "typing._UnionGenericAlias". This class is no longer
    needed for the implementation, but it has been retained for
    backward compatibility, with removal scheduled for Python 3.17.
    Users should use documented introspection helpers like
    "typing.get_origin()" and "typing.get_args()" instead of relying
    on private implementation details.

  * "typing.ByteString", deprecated since Python 3.9, is scheduled for
    removal in Python 3.17.

    Use "isinstance(obj, collections.abc.Buffer)" to test if "obj"
    implements the buffer protocol at runtime. For use in type
    annotations, either use "Buffer" or a union that explicitly
    specifies the types your code supports (e.g., "bytes | bytearray |
    memoryview").

    "ByteString" was originally intended to be an abstract class that
    would serve as a supertype of both "bytes" and "bytearray".
    However, since the ABC never had any methods, knowing that an
    object was an instance of "ByteString" never actually told you
    anything useful about the object. Other common buffer types such
    as "memoryview" were also never understood as subtypes of
    "ByteString" (either at runtime or by static type checkers).

    See **PEP 688** for more details. (Contributed by Shantanu Jain in
    gh-91896.)

* "tkinter":

  * The "tkinter.Variable" methods "trace_variable()", "trace()" (an
    alias of "trace_variable()"), "trace_vdelete()" and
    "trace_vinfo()", deprecated since Python 3.14, are scheduled for
    removal in Python 3.17. Use "trace_add()", "trace_remove()" and
    "trace_info()" instead. (Contributed by Serhiy Storchaka in
    gh-120220.)


Pending removal in Python 3.18
==============================

* No longer accept a boolean value when a file descriptor is expected.
  (Contributed by Serhiy Storchaka in gh-82626.)

* "decimal":

  * The non-standard and undocumented "Decimal" format specifier
    "'N'", which is only supported in the "decimal" module’s C
    implementation, has been deprecated since Python 3.13.
    (Contributed by Serhiy Storchaka in gh-89902.)

* Deprecations defined by **PEP 829**:

  * "import" lines in "*name*.pth" files are silently ignored.

  (Contributed by Barry Warsaw in gh-148641.)


Pending removal in Python 3.19
==============================

* "ctypes":

  * Implicitly switching to the MSVC-compatible struct layout by
    setting "_pack_" but not "_layout_" on non-Windows platforms.

* "hashlib":

  * In hash function constructors such as "new()" or the direct hash-
    named constructors such as "md5()" and "sha256()", their optional
    initial data parameter could also be passed a keyword argument
    named "data=" or "string=" in various "hashlib" implementations.

    Support for the "string" keyword argument name is now deprecated
    and slated for removal in Python 3.19.

    Before Python 3.13, the "string" keyword parameter was not
    correctly supported depending on the backend implementation of
    hash functions. Prefer passing the initial data as a positional
    argument for maximum backwards compatibility.

* "http.cookies":

  * "http.cookies.Morsel.js_output()" is deprecated and will be
    removed in Python 3.19.

  * "http.cookies.BaseCookie.js_output()" is deprecated and will be
    removed in Python 3.19.

* "imaplib":

  * Altering "IMAP4.file" is now deprecated and slated for removal in
    Python 3.19. This property is now unused and changing its value
    does not automatically close the current file.

    Before Python 3.14, this property was used to implement the
    corresponding "read()" and "readline()" methods for "IMAP4" but
    this is no longer the case since then.


Pending removal in Python 3.20
==============================

* Calling the "__new__()" method of "struct.Struct" without the
  *format* argument is deprecated and will be removed in Python 3.20.
  Calling "__init__()" method on initialized "Struct" objects is
  deprecated and will be removed in Python 3.20.

  (Contributed by Sergey B Kirpichev and Serhiy Storchaka in
  gh-143715.)

* The "__version__", "version" and "VERSION" attributes have been
  deprecated in these standard library modules and will be removed in
  Python 3.20. Use "sys.version_info" instead.

  * "argparse"

  * "csv"

  * "ctypes"

  * "ctypes.macholib"

  * "decimal" (use "decimal.SPEC_VERSION" instead)

  * "http.server"

  * "imaplib"

  * "ipaddress"

  * "json"

  * "logging" ("__date__" also deprecated)

  * "optparse"

  * "pickle"

  * "platform"

  * "re"

  * "socketserver"

  * "tabnanny"

  * "tarfile"

  * "tkinter.font"

  * "tkinter.ttk"

  * "wsgiref.simple_server"

  * "xml.etree.ElementTree"

  * "xml.sax.expatreader"

  * "xml.sax.handler"

  * "zlib"

  (Contributed by Hugo van Kemenade and Stan Ulbrych in gh-76007.)

* Deprecations defined by **PEP 829**:

  * Warnings are produced for "import" lines found in "*name*.pth"
    files.

  * "*name*.pth" files are no longer decoded in the locale encoding by
    default.  They **MUST** be encoded in "utf-8-sig".

  (Contributed by Barry Warsaw in gh-148641.)

* "ast":

  * Creating instances of abstract AST nodes (such as "ast.AST" or
    "ast.expr") is deprecated and will raise an error in Python 3.20.

* "typing":

  * It is deprecated to call "isinstance()" and "issubclass()" checks
    on protocol classes that were not explicitly decorated with
    "runtime_checkable()" but that inherit from a runtime-checkable
    protocol class. This will raise a "TypeError" in Python 3.20.

    (Contributed by Bartosz Sławecki in gh-132604.)


Pending removal in future versions
==================================

The following APIs will be removed in the future, although there is
currently no date scheduled for their removal.

* "argparse":

  * Nesting argument groups and nesting mutually exclusive groups are
    deprecated.

  * Passing the undocumented keyword argument *prefix_chars* to
    "add_argument_group()" is now deprecated.

  * The "argparse.FileType" type converter is deprecated.

* "builtins":

  * 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".

  * Passing a complex number as the *real* or *imag* argument in the
    "complex()" constructor is now deprecated; it should only be
    passed as a single positional argument. (Contributed by Serhiy
    Storchaka in gh-109218.)

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

* "codecs": use "open()" instead of "codecs.open()". (gh-133038)

* "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":

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

* "importlib.metadata":

  * "EntryPoints" tuple interface.

  * Implicit "None" on return values.

* "logging": the "warn()" method has been deprecated since Python 3.3,
  use "warning()" instead.

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

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

* "os.path": "os.path.commonprefix()" is deprecated, use
  "os.path.commonpath()" for path prefixes. The
  "os.path.commonprefix()" function is being deprecated due to having
  a misleading name and module. The function is not safe to use for
  path prefixes despite being included in a module about path
  manipulation, meaning it is easy to accidentally introduce path
  traversal vulnerabilities into Python programs by using this
  function.

* "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.)

* "shutil": "rmtree()"’s *onerror* parameter is deprecated in Python
  3.12; use the *onexc* parameter instead.

* "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"

* "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).

* The internal class "typing._UnionGenericAlias" is no longer used to
  implement "typing.Union". To preserve compatibility with users using
  this private class, a compatibility shim will be provided until at
  least Python 3.17. (Contributed by Jelle Zijlstra in gh-105499.)

* "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()"

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

* "xml.etree.ElementTree": Testing the truth value of an "Element" is
  deprecated. In a future release it will always return "True". Prefer
  explicit "len(elem)" or "elem is not None" tests instead.

* "sys._clear_type_cache()" is deprecated: use
  "sys._clear_internal_caches()" instead.


Soft deprecations
=================

There are no plans to remove *soft deprecated* APIs.

* "re.match()" and "re.Pattern.match()" are now *soft deprecated* in
  favor of the new "re.prefixmatch()" and "re.Pattern.prefixmatch()"
  APIs, which have been added as alternate, more explicit names. These
  are intended to be used to alleviate confusion around what *match*
  means by following the Zen of Python’s *“Explicit is better than
  implicit”* mantra. Most other language regular expression libraries
  use an API named *match* to mean what Python has always called
  *search*.

  We **do not** plan to remove the older "match()" name, as it has
  been used in code for over 30 years. Code supporting older versions
  of Python should continue to use "match()", while new code should
  prefer "prefixmatch()". See prefixmatch() vs. match().

  (Contributed by Gregory P. Smith in gh-86519 and Hugo van Kemenade
  in gh-148100.)

* Using "'F'" and "'D'" format type codes of the "struct" module now
  are *soft deprecated* in favor of two-letter forms "'Zf'" and
  "'Zd'". (Contributed by Sergey B Kirpichev in gh-121249.)


C API deprecations
==================


Pending removal in Python 3.15
------------------------------

* The "PyImport_ImportModuleNoBlock()": Use "PyImport_ImportModule()"
  instead.

* "PyWeakref_GetObject()" and "PyWeakref_GET_OBJECT()": Use
  "PyWeakref_GetRef()" instead. The pythoncapi-compat project can be
  used to get "PyWeakref_GetRef()" on Python 3.12 and older.

* "PyUnicode_AsDecodedObject()": Use "PyCodec_Decode()" instead.

* "PyUnicode_AsDecodedUnicode()": Use "PyCodec_Decode()" instead; Note
  that some codecs (for example, “base64”) may return a type other
  than "str", such as "bytes".

* "PyUnicode_AsEncodedObject()": Use "PyCodec_Encode()" instead.

* "PyUnicode_AsEncodedUnicode()": Use "PyCodec_Encode()" instead; Note
  that some codecs (for example, “base64”) may return a type other
  than "bytes", such as "str".

* Python initialization functions, deprecated in Python 3.13:

  * "Py_GetPath()": Use "PyConfig_Get("module_search_paths")"
    ("sys.path") instead.

  * "Py_GetPrefix()": Use "PyConfig_Get("base_prefix")"
    ("sys.base_prefix") instead. Use "PyConfig_Get("prefix")"
    ("sys.prefix") if virtual environments need to be handled.

  * "Py_GetExecPrefix()": Use "PyConfig_Get("base_exec_prefix")"
    ("sys.base_exec_prefix") instead. Use
    "PyConfig_Get("exec_prefix")" ("sys.exec_prefix") if virtual
    environments need to be handled.

  * "Py_GetProgramFullPath()": Use "PyConfig_Get("executable")"
    ("sys.executable") instead.

  * "Py_GetProgramName()": Use "PyConfig_Get("executable")"
    ("sys.executable") instead.

  * "Py_GetPythonHome()": Use "PyConfig_Get("home")" or the
    "PYTHONHOME" environment variable instead.

  The pythoncapi-compat project can be used to get "PyConfig_Get()" on
  Python 3.13 and older.

* Functions to configure Python’s initialization, deprecated in Python
  3.11:

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

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

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

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

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

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

* Global configuration variables:

  * "Py_DebugFlag": Use "PyConfig.parser_debug" or
    "PyConfig_Get("parser_debug")" instead.

  * "Py_VerboseFlag": Use "PyConfig.verbose" or
    "PyConfig_Get("verbose")" instead.

  * "Py_QuietFlag": Use "PyConfig.quiet" or "PyConfig_Get("quiet")"
    instead.

  * "Py_InteractiveFlag": Use "PyConfig.interactive" or
    "PyConfig_Get("interactive")" instead.

  * "Py_InspectFlag": Use "PyConfig.inspect" or
    "PyConfig_Get("inspect")" instead.

  * "Py_OptimizeFlag": Use "PyConfig.optimization_level" or
    "PyConfig_Get("optimization_level")" instead.

  * "Py_NoSiteFlag": Use "PyConfig.site_import" or
    "PyConfig_Get("site_import")" instead.

  * "Py_BytesWarningFlag": Use "PyConfig.bytes_warning" or
    "PyConfig_Get("bytes_warning")" instead.

  * "Py_FrozenFlag": Use "PyConfig.pathconfig_warnings" or
    "PyConfig_Get("pathconfig_warnings")" instead.

  * "Py_IgnoreEnvironmentFlag": Use "PyConfig.use_environment" or
    "PyConfig_Get("use_environment")" instead.

  * "Py_DontWriteBytecodeFlag": Use "PyConfig.write_bytecode" or
    "PyConfig_Get("write_bytecode")" instead.

  * "Py_NoUserSiteDirectory": Use "PyConfig.user_site_directory" or
    "PyConfig_Get("user_site_directory")" instead.

  * "Py_UnbufferedStdioFlag": Use "PyConfig.buffered_stdio" or
    "PyConfig_Get("buffered_stdio")" instead.

  * "Py_HashRandomizationFlag": Use "PyConfig.use_hash_seed" and
    "PyConfig.hash_seed" or "PyConfig_Get("hash_seed")" instead.

  * "Py_IsolatedFlag": Use "PyConfig.isolated" or
    "PyConfig_Get("isolated")" instead.

  * "Py_LegacyWindowsFSEncodingFlag": Use
    "PyPreConfig.legacy_windows_fs_encoding" or
    "PyConfig_Get("legacy_windows_fs_encoding")" instead.

  * "Py_LegacyWindowsStdioFlag": Use "PyConfig.legacy_windows_stdio"
    or "PyConfig_Get("legacy_windows_stdio")" instead.

  * "Py_FileSystemDefaultEncoding", "Py_HasFileSystemDefaultEncoding":
    Use "PyConfig.filesystem_encoding" or
    "PyConfig_Get("filesystem_encoding")" instead.

  * "Py_FileSystemDefaultEncodeErrors": Use
    "PyConfig.filesystem_errors" or
    "PyConfig_Get("filesystem_errors")" instead.

  * "Py_UTF8Mode": Use "PyPreConfig.utf8_mode" or
    "PyConfig_Get("utf8_mode")" instead. (see "Py_PreInitialize()")

  The "Py_InitializeFromConfig()" API should be used with "PyConfig"
  to set these options. Or "PyConfig_Get()" can be used to get these
  options at runtime.


Pending removal in Python 3.16
------------------------------

* The bundled copy of "libmpdec".


Pending removal in Python 3.18
------------------------------

* The following private functions are deprecated and planned for
  removal in Python 3.18:

  * "_PyBytes_Join()": use "PyBytes_Join()".

  * "_PyDict_GetItemStringWithError()": use
    "PyDict_GetItemStringRef()".

  * "_PyDict_Pop()": use "PyDict_Pop()".

  * "_PyLong_Sign()": use "PyLong_GetSign()".

  * "_PyLong_FromDigits()" and "_PyLong_New()": use
    "PyLongWriter_Create()".

  * "_PyThreadState_UncheckedGet()": use
    "PyThreadState_GetUnchecked()".

  * "_PyUnicode_AsString()": use "PyUnicode_AsUTF8()".

  * "_PyUnicodeWriter_Init()": replace
    "_PyUnicodeWriter_Init(&writer)" with "writer =
    PyUnicodeWriter_Create(0)".

  * "_PyUnicodeWriter_Finish()": replace
    "_PyUnicodeWriter_Finish(&writer)" with
    "PyUnicodeWriter_Finish(writer)".

  * "_PyUnicodeWriter_Dealloc()": replace
    "_PyUnicodeWriter_Dealloc(&writer)" with
    "PyUnicodeWriter_Discard(writer)".

  * "_PyUnicodeWriter_WriteChar()": replace
    "_PyUnicodeWriter_WriteChar(&writer, ch)" with
    "PyUnicodeWriter_WriteChar(writer, ch)".

  * "_PyUnicodeWriter_WriteStr()": replace
    "_PyUnicodeWriter_WriteStr(&writer, str)" with
    "PyUnicodeWriter_WriteStr(writer, str)".

  * "_PyUnicodeWriter_WriteSubstring()": replace
    "_PyUnicodeWriter_WriteSubstring(&writer, str, start, end)" with
    "PyUnicodeWriter_WriteSubstring(writer, str, start, end)".

  * "_PyUnicodeWriter_WriteASCIIString()": replace
    "_PyUnicodeWriter_WriteASCIIString(&writer, str)" with
    "PyUnicodeWriter_WriteASCII(writer, str)".

  * "_PyUnicodeWriter_WriteLatin1String()": replace
    "_PyUnicodeWriter_WriteLatin1String(&writer, str)" with
    "PyUnicodeWriter_WriteUTF8(writer, str)".

  * "_PyUnicodeWriter_Prepare()": (no replacement).

  * "_PyUnicodeWriter_PrepareKind()": (no replacement).

  * "_Py_HashPointer()": use "Py_HashPointer()".

  * "_Py_fopen_obj()": use "Py_fopen()".

  The pythoncapi-compat project can be used to get these new public
  functions on Python 3.13 and older. (Contributed by Victor Stinner
  in gh-128863.)


Pending removal in Python 3.19
------------------------------

* **PEP 456** embedders support for the string hashing scheme
  definition.


Pending removal in Python 3.20
------------------------------

* "_PyObject_CallMethodId()", "_PyObject_GetAttrId()" and
  "_PyUnicode_FromId()" are deprecated since 3.15 and will be removed
  in 3.20. Instead, use "PyUnicode_InternFromString()" and cache the
  result in the module state, then call "PyObject_CallMethod()" or
  "PyObject_GetAttr()". (Contributed by Victor Stinner in gh-141049.)

* The "cval" field in "PyComplexObject" (gh-128813). Use
  "PyComplex_AsCComplex()" and "PyComplex_FromCComplex()" to convert a
  Python complex number to/from the C "Py_complex" representation.

* Macros "Py_MATH_PIl" and "Py_MATH_El".


Pending removal in future versions
----------------------------------

The following APIs are deprecated and will be removed, although there
is currently no date scheduled for their removal.

* "Py_TPFLAGS_HAVE_FINALIZE": Unneeded since Python 3.8.

* "PyErr_Fetch()": Use "PyErr_GetRaisedException()" instead.

* "PyErr_NormalizeException()": Use "PyErr_GetRaisedException()"
  instead.

* "PyErr_Restore()": Use "PyErr_SetRaisedException()" instead.

* "PyModule_GetFilename()": Use "PyModule_GetFilenameObject()"
  instead.

* "PyOS_AfterFork()": Use "PyOS_AfterFork_Child()" instead.

* "PySlice_GetIndicesEx()": Use "PySlice_Unpack()" and
  "PySlice_AdjustIndices()" instead.

* "PyUnicode_READY()": Unneeded since Python 3.12

* "PyErr_Display()": Use "PyErr_DisplayException()" instead.

* "_PyErr_ChainExceptions()": Use "_PyErr_ChainExceptions1()" instead.

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

* Thread Local Storage (TLS) API:

  * "PyThread_create_key()": Use "PyThread_tss_alloc()" instead.

  * "PyThread_delete_key()": Use "PyThread_tss_free()" instead.

  * "PyThread_set_key_value()": Use "PyThread_tss_set()" instead.

  * "PyThread_get_key_value()": Use "PyThread_tss_get()" instead.

  * "PyThread_delete_key_value()": Use "PyThread_tss_delete()"
    instead.

  * "PyThread_ReInitTLS()": Unneeded since Python 3.7.
