What’s New In Python 3.9¶

This article explains the new features in Python 3.9, compared to 3.8.

When Python 2.7 was still supported, many functions were kept for backward compatibility with Python 2.7. With the end of Python 2.7 support, these backward compatibility layers have been removed, or will be removed soon. Most of them emitted a DeprecationWarning warning for several years. For example, using collections.Mapping instead of collections.abc.Mapping emits a DeprecationWarning since Python 3.3, released in 2012.

Test your application with the -W default command-line option to see DeprecationWarning and PendingDeprecationWarning, or even with -W error to treat them as errors. Warnings Filter can be used to ignore warnings from third-party code.

It has been decided to keep a few backward compatibility layers for one last release, to give more time to Python projects maintainers to organize the removal of the Python 2 support and add support for Python 3.9.

Aliases to Abstract Base Classes in the collections module, like collections.Mapping alias to collections.abc.Mapping, are kept for one last release for backward compatibility. They will be removed from Python 3.10.

More generally, try to run your tests in the Python Development Mode which helps to prepare your code to make it compatible with the next Python version.

In type annotations you can now use built-in collection types such as list and dict as generic types instead of importing the corresponding capitalized types (e.g. List or Dict) from typing. Some other types in the standard library are also now generic, for example queue.Queue.


def greet_all(names: list[str]) -> None: for name in names: print("Hello", name)

See PEP 585 for more details. (Contributed by Guido van Rossum, Ethan Smith, and Batuhan Taşkaya in bpo-39481.)

Python 3.9 uses a new parser, based on PEG instead of LL(1). The new parser’s performance is roughly comparable to that of the old parser, but the PEG formalism is more flexible than LL(1) when it comes to designing new language features. We’ll start using this flexibility in Python 3.10 and later.

The ast module uses the new parser and produces the same AST as the old parser.

In Python 3.10, the old parser will be deleted and so will all functionality that depends on it (primarily the parser module, which has long been deprecated). In Python 3.9 only, you can switch back to the LL(1) parser using a command line switch (-X oldparser) or an environment variable (PYTHONOLDPARSER=1).

See PEP 617 for more details. (Contributed by Guido van Rossum, Pablo Galindo and Lysandros Nikolaou in bpo-40334.)

Added the indent option to dump() which allows it to produce a multiline indented output. (Contributed by Serhiy Storchaka in bpo-37995.)

Added ast.unparse() as a function in the ast module that can be used to unparse an ast.AST object and produce a string with code that would produce an equivalent ast.AST object when parsed. (Contributed by Pablo Galindo and Batuhan Taskaya in bpo-38870.)

Added docstrings to AST nodes that contains the ASDL signature used to construct that node. (Contributed by Batuhan Taskaya in bpo-39638.)

Due to significant security concerns, the reuse_address parameter of asyncio.loop.create_datagram_endpoint() is no longer supported. This is because of the behavior of the socket option SO_REUSEADDR in UDP. For more details, see the documentation for loop.create_datagram_endpoint(). (Contributed by Kyle Stanley, Antoine Pitrou, and Yury Selivanov in bpo-37228.)

Added a new coroutine shutdown_default_executor() that schedules a shutdown for the default executor that waits on the ThreadPoolExecutor to finish closing. Also, asyncio.run() has been updated to use the new coroutine. (Contributed by Kyle Stanley in bpo-34037.)

Added asyncio.PidfdChildWatcher, a Linux-specific child watcher implementation that polls process file descriptors. (bpo-38692)

Added a new coroutine asyncio.to_thread(). It is mainly used for running IO-bound functions in a separate thread to avoid blocking the event loop, and essentially works as a high-level version of run_in_executor() that can directly take keyword arguments. (Contributed by Kyle Stanley and Yury Selivanov in bpo-32309.)

Added new possibility to use hardlinks for duplicated .pyc files: hardlink_dupes parameter and –hardlink-dupes command line option. (Contributed by Lumír ‘Frenzy’ Balhar in bpo-40495.)

Added new options for path manipulation in resulting .pyc files: stripdir, prependdir, limit_sl_dest parameters and -s, -p, -e command line options. Added the possibility to specify the option for an optimization level multiple times. (Contributed by Lumír ‘Frenzy’ Balhar in bpo-38112.)

Added a new cancel_futures parameter to concurrent.futures.Executor.shutdown() that cancels all pending futures which have not started running, instead of waiting for them to complete before shutting down the executor. (Contributed by Kyle Stanley in bpo-39349.)

Removed daemon threads from ThreadPoolExecutor and ProcessPoolExecutor. This improves compatibility with subinterpreters and predictability in their shutdown processes. (Contributed by Kyle Stanley in bpo-39812.)

Workers in ProcessPoolExecutor are now spawned on demand, only when there are no available idle workers to reuse. This optimizes startup overhead and reduces the amount of lost CPU time to idle workers. (Contributed by Kyle Stanley in bpo-39207.)

The upload command now creates SHA2-256 and Blake2b-256 hash digests. It skips MD5 on platforms that block MD5 digest. (Contributed by Christian Heimes in bpo-40698.)

Added constants F_OFD_GETLK, F_OFD_SETLK and F_OFD_SETLKW. (Contributed by Dong-hee Na in bpo-38602.)

FTP and FTP_TLS now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. (Contributed by Dong-hee Na in bpo-39259.)

When the garbage collector makes a collection in which some objects resurrect (they are reachable from outside the isolated cycles after the finalizers have been executed), do not block the collection of all objects that are still unreachable. (Contributed by Pablo Galindo and Tim Peters in bpo-38379.)

Added a new function gc.is_finalized() to check if an object has been finalized by the garbage collector. (Contributed by Pablo Galindo in bpo-39322.)

Builtin hash modules can now be disabled with ./configure --without-builtin-hashlib-hashes or selectively enabled with e.g. ./configure --with-builtin-hashlib-hashes=sha3,blake2 to force use of OpenSSL based implementation. (Contributed by Christian Heimes in bpo-40479)

HTTP status codes 103 EARLY_HINTS, 418 IM_A_TEAPOT and 425 TOO_EARLY are added to http.HTTPStatus. (Contributed by Dong-hee Na in bpo-39509 and Ross Rhodes in bpo-39507.)

IMAP4 and IMAP4_SSL now have an optional timeout parameter for their constructors. Also, the open() method now has an optional timeout parameter with this change. The overridden methods of IMAP4_SSL and IMAP4_stream were applied to this change. (Contributed by Dong-hee Na in bpo-38615.)

imaplib.IMAP4.unselect() is added. imaplib.IMAP4.unselect() frees server’s resources associated with the selected mailbox and returns the server to the authenticated state. This command performs the same actions as imaplib.IMAP4.close(), except that no messages are permanently removed from the currently selected mailbox. (Contributed by Dong-hee Na in bpo-40375.)

ipaddress now supports IPv6 Scoped Addresses (IPv6 address with suffix %<scope_id>).

Scoped IPv6 addresses can be parsed using ipaddress.IPv6Address. If present, scope zone ID is available through the scope_id attribute. (Contributed by Oleksandr Pavliuk in bpo-34788.)

Expanded the math.gcd() function to handle multiple arguments. Formerly, it only supported two arguments. (Contributed by Serhiy Storchaka in bpo-39648.)

Add math.lcm(): return the least common multiple of specified arguments. (Contributed by Mark Dickinson, Ananthakrishnan and Serhiy Storchaka in bpo-39479 and bpo-39648.)

Add math.nextafter(): return the next floating-point value after x towards y. (Contributed by Victor Stinner in bpo-39288.)

Add math.ulp(): return the value of the least significant bit of a float. (Contributed by Victor Stinner in bpo-39310.)

NNTP and NNTP_SSL now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. (Contributed by Dong-hee Na in bpo-39259.)

POP3 and POP3_SSL now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. (Contributed by Dong-hee Na in bpo-39259.)

The documentation string is now shown not only for class, function, method etc, but for any object that has its own __doc__ attribute. (Contributed by Serhiy Storchaka in bpo-40257.)

Add a new random.Random.randbytes method: generate random bytes. (Contributed by Victor Stinner in bpo-40286.)

SMTP and SMTP_SSL now raise a ValueError if the given timeout for their constructor is zero to prevent the creation of a non-blocking socket. (Contributed by Dong-hee Na in bpo-39259.)

LMTP constructor now has an optional timeout parameter. (Contributed by Dong-hee Na in bpo-39329.)

The socket module now exports the CAN_RAW_JOIN_FILTERS constant on Linux 4.1 and greater. (Contributed by Stefan Tatschner and Zackery Spytz in bpo-25780.)

The socket module now supports the CAN_J1939 protocol on platforms that support it. (Contributed by Karl Ding in bpo-40291.)

On AIX, thread_time() is now implemented with thread_cputime() which has nanosecond resolution, rather than clock_gettime(CLOCK_THREAD_CPUTIME_ID) which has a resolution of 10 ms. (Contributed by Batuhan Taskaya in bpo-40192)

Add a new sys.platlibdir attribute: name of the platform-specific library directory. It is used to build the path of standard library and the paths of installed extension modules. It is equal to "lib" on most platforms. On Fedora and SuSE, it is equal to "lib64" on 64-bit platforms. (Contributed by Jan Matějek, Matěj Cepl, Charalampos Stratakis and Victor Stinner in bpo-1294959.)

Previously, sys.stderr was block-buffered when non-interactive. Now stderr defaults to always being line-buffered. (Contributed by Jendrik Seipp in bpo-13601.)

Added tracemalloc.reset_peak() to set the peak size of traced memory blocks to the current size, to measure the peak of specific pieces of code. (Contributed by Huon Wilson in bpo-40630.)

PEP 593 introduced an typing.Annotated type to decorate existing types with context-specific metadata and new include_extras parameter to typing.get_type_hints() to access the metadata at runtime. (Contributed by Till Varoquaux and Konstantin Kashin.)

The Unicode database has been updated to version 13.0.0. (bpo-39926).

The activation scripts provided by venv now all specify their prompt customization consistently by always using the value specified by __VENV_PROMPT__. Previously some scripts unconditionally used __VENV_PROMPT__, others only if it happened to be set (which was the default case), and one used __VENV_NAME__ instead. (Contributed by Brett Cannon in bpo-37663.)

White space characters within attributes are now preserved when serializing xml.etree.ElementTree to XML file. EOLNs are no longer normalized to “n”. This is the result of discussion about how to interpret section 2.11 of XML spec. (Contributed by Mefistotelis in bpo-39011.)

  • Optimized the idiom for assignment a temporary variable in comprehensions. Now for y in [expr] in comprehensions is as fast as a simple assignment y = expr. For example:

    sums = [s for s in [0] for x in data for s in [s + x]]

    Unlike the := operator this idiom does not leak a variable to the outer scope.

    (Contributed by Serhiy Storchaka in bpo-32856.)

  • Optimize signal handling in multithreaded applications. If a thread different than the main thread gets a signal, the bytecode evaluation loop is no longer interrupted at each bytecode instruction to check for pending signals which cannot be handled. Only the main thread of the main interpreter can handle signals.

    Previously, the bytecode evaluation loop was interrupted at each instruction until the main thread handles signals. (Contributed by Victor Stinner in bpo-40010.)

  • Optimize the subprocess module on FreeBSD using closefrom(). (Contributed by Ed Maste, Conrad Meyer, Kyle Evans, Kubilay Kocak and Victor Stinner in bpo-38061.)

Here’s a summary of performance improvements from Python 3.4 through Python 3.9:

Python version 3.4 3.5 3.6 3.7 3.8 3.9
-------------- --- --- --- --- --- --- Variable and attribute read access: read_local 7.1 7.1 5.4 5.1 3.9 4.0 read_nonlocal 7.1 8.1 5.8 5.4 4.4 4.8 read_global 15.5 19.0 14.3 13.6 7.6 7.7 read_builtin 21.1 21.6 18.5 19.0 7.5 7.7 read_classvar_from_class 25.6 26.5 20.7 19.5 18.4 18.6 read_classvar_from_instance 22.8 23.5 18.8 17.1 16.4 20.1 read_instancevar 32.4 33.1 28.0 26.3 25.4 27.7 read_instancevar_slots 27.8 31.3 20.8 20.8 20.2 24.5 read_namedtuple 73.8 57.5 45.0 46.8 18.4 23.2 read_boundmethod 37.6 37.9 29.6 26.9 27.7 45.9 Variable and attribute write access: write_local 8.7 9.3 5.5 5.3 4.3 4.2 write_nonlocal 10.5 11.1 5.6 5.5 4.7 4.9 write_global 19.7 21.2 18.0 18.0 15.8 17.2 write_classvar 92.9 96.0 104.6 102.1 39.2 43.2 write_instancevar 44.6 45.8 40.0 38.9 35.5 40.7 write_instancevar_slots 35.6 36.1 27.3 26.6 25.7 27.7 Data structure read access: read_list 24.2 24.5 20.8 20.8 19.0 21.1 read_deque 24.7 25.5 20.2 20.6 19.8 21.6 read_dict 24.3 25.7 22.3 23.0 21.0 22.5 read_strdict 22.6 24.3 19.5 21.2 18.9 21.6 Data structure write access: write_list 27.1 28.5 22.5 21.6 20.0 21.6 write_deque 28.7 30.1 22.7 21.8 23.5 23.2 write_dict 31.4 33.3 29.3 29.2 24.7 27.8 write_strdict 28.4 29.9 27.5 25.2 23.1 29.8 Stack (or queue) operations: list_append_pop 93.4 112.7 75.4 74.2 50.8 53.9 deque_append_pop 43.5 57.0 49.4 49.2 42.5 45.5 deque_append_popleft 43.7 57.3 49.7 49.7 42.8 45.5 Timing loop: loop_overhead 0.5 0.6 0.4 0.3 0.3 0.3

These results were generated from the variable access benchmark script at: Tools/scripts/var_access_benchmark.py. The benchmark script displays timings in nanoseconds. The benchmarks were measured on an Intel® Core™ i7-4960HQ processor running the macOS 64-bit builds found at python.org.

  • The distutils bdist_msi command is now deprecated, use bdist_wheel (wheel packages) instead. (Contributed by Hugo van Kemenade in bpo-39586.)

  • Currently math.factorial() accepts float instances with non-negative integer values (like 5.0). It raises a ValueError for non-integral and negative floats. It is now deprecated. In future Python versions it will raise a TypeError for all floats. (Contributed by Serhiy Storchaka in bpo-37315.)

  • The parser and symbol modules are deprecated and will be removed in future versions of Python. For the majority of use cases, users can leverage the Abstract Syntax Tree (AST) generation and compilation stage, using the ast module.

  • The Public C API functions PyParser_SimpleParseStringFlags(), PyParser_SimpleParseStringFlagsFilename(), PyParser_SimpleParseFileFlags() and PyNode_Compile() are deprecated and will be removed in Python 3.10 together with the old parser.

  • Using NotImplemented in a boolean context has been deprecated, as it is almost exclusively the result of incorrect rich comparator implementations. It will be made a TypeError in a future version of Python. (Contributed by Josh Rosenberg in bpo-35712.)

  • The random module currently accepts any hashable type as a possible seed value. Unfortunately, some of those types are not guaranteed to have a deterministic hash value. After Python 3.9, the module will restrict its seeds to None, int, float, str, bytes, and bytearray.

  • Opening the GzipFile file for writing without specifying the mode argument is deprecated. In future Python versions it will always be opened for reading by default. Specify the mode argument for opening it for writing and silencing a warning. (Contributed by Serhiy Storchaka in bpo-28286.)

  • Deprecated the split() method of _tkinter.TkappType in favour of the splitlist() method which has more consistent and predicable behavior. (Contributed by Serhiy Storchaka in bpo-38371.)

  • The explicit passing of coroutine objects to asyncio.wait() has been deprecated and will be removed in version 3.11. (Contributed by Yury Selivanov and Kyle Stanley in bpo-34790.)

  • binhex4 and hexbin4 standards are now deprecated. The binhex module and the following binascii functions are now deprecated:

    (Contributed by Victor Stinner in bpo-39353.)

  • ast classes slice, Index and ExtSlice are considered deprecated and will be removed in future Python versions. value itself should be used instead of Index(value). Tuple(slices, Load()) should be used instead of ExtSlice(slices). (Contributed by Serhiy Storchaka in bpo-32892.)

  • ast classes Suite, Param, AugLoad and AugStore are considered deprecated and will be removed in future Python versions. They were not generated by the parser and not accepted by the code generator in Python 3. (Contributed by Batuhan Taskaya in bpo-39639 and bpo-39969 and Serhiy Storchaka in bpo-39988.)

  • The PyEval_InitThreads() and PyEval_ThreadsInitialized() functions are now deprecated and will be removed in Python 3.11. Calling PyEval_InitThreads() now does nothing. The GIL is initialized by Py_Initialize() since Python 3.7. (Contributed by Victor Stinner in bpo-39877.)

  • Passing None as the first argument to the shlex.split() function has been deprecated. (Contributed by Zackery Spytz in bpo-33262.)

  • The lib2to3 module now emits a PendingDeprecationWarning. Python 3.9 switched to a PEG parser (see PEP 617), and Python 3.10 may include new language syntax that is not parsable by lib2to3’s LL(1) parser. The lib2to3 module may be removed from the standard library in a future Python version. Consider third-party alternatives such as LibCST or parso. (Contributed by Carl Meyer in bpo-40360.)

  • The random parameter of random.shuffle() has been deprecated. (Contributed by Raymond Hettinger in bpo-40465)

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

Changes in the Python API

  • __import__() and importlib.util.resolve_name() now raise ImportError where it previously raised ValueError. Callers catching the specific exception type and supporting both Python 3.9 and earlier versions will need to catch both using except (ImportError, ValueError):.

  • The venv activation scripts no longer special-case when __VENV_PROMPT__ is set to "".

  • The select.epoll.unregister() method no longer ignores the EBADF error. (Contributed by Victor Stinner in bpo-39239.)

  • The compresslevel parameter of bz2.BZ2File became keyword-only, since the buffering parameter has been removed. (Contributed by Victor Stinner in bpo-39357.)

  • Simplified AST for subscription. Simple indices will be represented by their value, extended slices will be represented as tuples. Index(value) will return a value itself, ExtSlice(slices) will return Tuple(slices, Load()). (Contributed by Serhiy Storchaka in bpo-34822.)

  • The importlib module now ignores the PYTHONCASEOK environment variable when the -E or -I command line options are being used.

  • The encoding parameter has been added to the classes ftplib.FTP and ftplib.FTP_TLS as a keyword-only parameter, and the default encoding is changed from Latin-1 to UTF-8 to follow RFC 2640.

  • asyncio.loop.shutdown_default_executor() has been added to AbstractEventLoop, meaning alternative event loops that inherit from it should have this method defined. (Contributed by Kyle Stanley in bpo-34037.)

  • The constant values of future flags in the __future__ module is updated in order to prevent collision with compiler flags. Previously PyCF_ALLOW_TOP_LEVEL_AWAIT was clashing with CO_FUTURE_DIVISION. (Contributed by Batuhan Taskaya in bpo-39562)

  • array('u') now uses wchar_t as C type instead of Py_UNICODE. This change doesn’t affect to its behavior because Py_UNICODE is alias of wchar_t since Python 3.3. (Contributed by Inada Naoki in bpo-34538.)

Changes in the C API

  • Instances of heap-allocated types (such as those created with PyType_FromSpec() and similar APIs) hold a reference to their type object since Python 3.8. As indicated in the “Changes in the C API” of Python 3.8, for the vast majority of cases, there should be no side effect but for types that have a custom tp_traverse function, ensure that all custom tp_traverse functions of heap-allocated types visit the object’s type.


    foo_traverse(foo_struct *self, visitproc visit, void *arg) {
    // Rest of the traverse function
    #if PY_VERSION_HEX >= 0x03090000 // This was not needed before Python 3.9 (Python issue 35810 and 40217) Py_VISIT(Py_TYPE(self));

    If your traverse function delegates to tp_traverse of its base class (or another type), ensure that Py_TYPE(self) is visited only once. Note that only heap types are expected to visit the type in tp_traverse.

    For example, if your tp_traverse function includes:

    base->tp_traverse(self, visit, arg)

    then add:

    #if PY_VERSION_HEX >= 0x03090000 // This was not needed before Python 3.9 (Python issue 35810 and 40217) if (base->tp_flags & Py_TPFLAGS_HEAPTYPE) { // a heap type's tp_traverse already visited Py_TYPE(self) } else { Py_VISIT(Py_TYPE(self)); }

    (See bpo-35810 and bpo-40217 for more information.)

CPython bytecode changes

New Features

Porting to Python 3.9

  • PyInterpreterState.eval_frame (PEP 523) now requires a new mandatory tstate parameter (PyThreadState*). (Contributed by Victor Stinner in bpo-38500.)

  • Extension modules: m_traverse, m_clear and m_free functions of PyModuleDef are no longer called if the module state was requested but is not allocated yet. This is the case immediately after the module is created and before the module is executed (Py_mod_exec function). More precisely, these functions are not called if m_size is greater than 0 and the module state (as returned by PyModule_GetState()) is NULL.

    Extension modules without module state (m_size <= 0) are not affected.

  • If Py_AddPendingCall() is called in a subinterpreter, the function is now scheduled to be called from the subinterpreter, rather than being called from the main interpreter. Each subinterpreter now has its own list of scheduled calls. (Contributed by Victor Stinner in bpo-39984.)

  • The Windows registry is no longer used to initialize sys.path when the -E option is used (if PyConfig.use_environment is set to 0). This is significant when embedding Python on Windows. (Contributed by Zackery Spytz in bpo-8901.)

  • The global variable PyStructSequence_UnnamedField is now a constant and refers to a constant string. (Contributed by Serhiy Storchaka in bpo-38650.)

  • The PyGC_Head structure is now opaque. It is only defined in the internal C API (pycore_gc.h). (Contributed by Victor Stinner in bpo-40241.)

  • The Py_UNICODE_COPY, Py_UNICODE_FILL, PyUnicode_WSTR_LENGTH, PyUnicode_FromUnicode(), PyUnicode_AsUnicode(), _PyUnicode_AsUnicode, and PyUnicode_AsUnicodeAndSize() are marked as deprecated in C. They have been deprecated by PEP 393 since Python 3.3. (Contributed by Inada Naoki in bpo-36346.)


  • Exclude PyFPE_START_PROTECT() and PyFPE_END_PROTECT() macros of pyfpe.h from the limited C API. (Contributed by Victor Stinner in bpo-38835.)

  • The tp_print slot of PyTypeObject has been removed. It was used for printing objects to files in Python 2.7 and before. Since Python 3.0, it has been ignored and unused. (Contributed by Jeroen Demeyer in bpo-36974.)

  • Changes in the limited C API (if Py_LIMITED_API macro is defined):

    • Exclude the following functions from the limited C API:

      • PyThreadState_DeleteCurrent() (Contributed by Joannah Nanjekye in bpo-37878.)

      • _Py_CheckRecursionLimit

      • _Py_NewReference()

      • _Py_ForgetReference()

      • _PyTraceMalloc_NewReference()

      • _Py_GetRefTotal()

      • The trashcan mechanism which never worked in the limited C API.

      • PyTrash_UNWIND_LEVEL






    • Move following functions and definitions to the internal C API:

      • _PyDebug_PrintTotalRefs()

      • _Py_PrintReferences()

      • _Py_PrintReferenceAddresses()

      • _Py_tracemalloc_config

      • _Py_AddToAllObjects() (specific to Py_TRACE_REFS build)

    (Contributed by Victor Stinner in bpo-38644 and bpo-39542.)

  • Remove _PyRuntime.getframe hook and remove _PyThreadState_GetFrame macro which was an alias to _PyRuntime.getframe. They were only exposed by the internal C API. Remove also PyThreadFrameGetter type. (Contributed by Victor Stinner in bpo-39946.)

  • Remove the following functions from the C API. Call PyGC_Collect() explicitly to clear all free lists. (Contributed by Inada Naoki and Victor Stinner in bpo-37340, bpo-38896 and bpo-40428.)

    • PyAsyncGen_ClearFreeLists()

    • PyContext_ClearFreeList()

    • PyDict_ClearFreeList()

    • PyFloat_ClearFreeList()

    • PyFrame_ClearFreeList()

    • PyList_ClearFreeList()

    • PyMethod_ClearFreeList() and PyCFunction_ClearFreeList(): the free lists of bound method objects have been removed.

    • PySet_ClearFreeList(): the set free list has been removed in Python 3.4.

    • PyTuple_ClearFreeList()

    • PyUnicode_ClearFreeList(): the Unicode free list has been removed in Python 3.3.

  • Remove _PyUnicode_ClearStaticStrings() function. (Contributed by Victor Stinner in bpo-39465.)

  • Remove Py_UNICODE_MATCH. It has been deprecated by PEP 393, and broken since Python 3.3. The PyUnicode_Tailmatch() function can be used instead. (Contributed by Inada Naoki in bpo-36346.)