Python 3.8.6 final
Core and Builtins
bpo-41525: The output of python --help contains now only ASCII characters.
Library
bpo-41817: fix tkinter.EventType Enum so all members are strings, and none are tuples
bpo-41815: Fix SQLite3 segfault when backing up closed database. Patch contributed by Peter David McCormick.
bpo-41517: fix bug allowing Enums to be extended via multiple inheritance
bpo-39587: use the correct mix-in data type when constructing Enums
bpo-41789: Honor object overrides in Enum class creation (specifically, __str__, __repr__, __format__, and __reduce_ex__).
bpo-39651: Fix a race condition in the call_soon_threadsafe() method of asyncio.ProactorEventLoop: do nothing if the self-pipe socket has been closed.
bpo-41720: Fixed turtle.Vec2D.__rmul__() for arguments which are not int or float.
bpo-39728: fix default _missing_ so a duplicate ValueError is not set as the __context__ of the original ValueError
bpo-37479: When Enum.__str__ is overridden in a derived class, the override will be used by Enum.__format__ regardless of whether mixin classes are present.
Documentation
bpo-35293: Fix RemovedInSphinx40Warning when building the documentation. Patch by Dong-hee Na.
bpo-37149: Change Shipman tkinter doc link from archive.org to TkDocs. (The doc has been removed from the NMT server.) The new link responds much faster and includes a short explanatory note.
Tests
bpo-41731: Make test_cmd_line_script pass with option ‘-vv’.
Windows
bpo-41744: Fixes automatic import of props file when using the Nuget package.
IDLE
bpo-35764: Rewrite the Calltips doc section.
bpo-40181: In calltips, stop reminding that ‘/’ marks the end of positional-only arguments.
Python 3.8.6 release candidate 1
Core and Builtins
bpo-41654: Fix a crash that occurred when destroying subclasses of MemoryError. Patch by Pablo Galindo.
bpo-41533: Free the stack allocated in va_build_stack if do_mkstack fails and the stack is not a small_stack.
bpo-38156: Handle interrupts that come after EOF correctly in PyOS_StdioReadline.
Library
bpo-41696: Fix handling of debug mode in asyncio.run(). This allows setting PYTHONASYNCIODEBUG or -X dev to enable asyncio debug mode when using asyncio.run().
bpo-39010: Restarting a ProactorEventLoop on Windows no longer logs spurious ConnectionResetErrors.
bpo-41609: The pdb whatis command correctly reports instance methods as ‘Method’ rather than ‘Function’.
bpo-32751: When cancelling the task due to a timeout, asyncio.wait_for() will now wait until the cancellation is complete also in the case when timeout is <= 0, like it does with positive timeouts.
bpo-37658: asyncio.wait_for() now properly handles races between cancellation of itself and the completion of the wrapped awaitable.
bpo-40782: Change the method asyncio.AbstractEventLoop.run_in_executor to not be a coroutine.
bpo-41520: Fix codeop regression that prevented turning compile warnings into errors.
bpo-41503: Fixed a race between setTarget and flush in logging.handlers.MemoryHandler.
bpo-41497: Fix potential UnicodeDecodeError in dis module.
bpo-41490: Update ensurepip to install pip 20.2.1 and setuptools 49.2.1.
bpo-41467: On Windows, fix asyncio recv_into() return value when the socket/pipe is closed (BrokenPipeError): return 0 rather than an empty byte string (b'').
bpo-41425: Make tkinter doc example runnable.
bpo-41384: Raise TclError instead of TypeError when an unknown option is passed to tkinter.OptionMenu.
bpo-38731: Fix NameError in command-line interface of py_compile.
bpo-41364: Reduce import overhead of uuid.
bpo-41344: Prevent creating shared_memory.SharedMemory objects with size=0.
bpo-40726: Handle cases where the end_lineno is None on ast.increment_lineno().
bpo-31122: ssl.wrap_socket() now raises ssl.SSLEOFError rather than OSError when peer closes connection during TLS negotiation
bpo-33660: Fix pathlib.PosixPath to resolve a relative path located on the root directory properly.
Documentation
bpo-41624: Fix the signature of typing.Coroutine.
bpo-40204: Enable Sphinx 3.2 c_allow_pre_v3 option and disable c_warn_on_allowed_pre_v3 option to make the documentation compatible with Sphinx 2 and Sphinx 3.
bpo-41045: Add documentation for debug feature of f-strings.
bpo-41314: Changed the release when from __future__ import annotations becomes the default from 4.0 to 3.10 (following a change in PEP 563).
bpo-39883: Make code, examples, and recipes in the Python documentation be licensed under the more permissive BSD0 license in addition to the existing Python 2.0 license.
Windows
bpo-41492: Fixes the description that appears in UAC prompts.
bpo-40741: Update Windows release to include SQLite 3.32.3.
IDLE
bpo-41468: Improve IDLE run crash error message (which users should never see).
bpo-41373: Save files loaded with no line ending, as when blank, or different line endings, by setting its line ending to the system default. Fix regression in 3.8.4 and 3.9.0b4.
C API
bpo-41524: Fix bug in PyOS_mystrnicmp and PyOS_mystricmp that incremented pointers beyond the end of a string.
1. LD_LIBRARY_PATH does _not_ take precedence over DT_RPATH
(e.g. Linux)
2. A previous libpython with the same major.minor is already installed
(e.g. a previous version of this package)
hold, the built python will be linked with the installed libpython,
causing it to report an old teeny version in sys.version_info while
staging the install. Then "make package" fails with PLIST mismatches for
{,Pattern}Grammar.*.pickle.
pkgsrc knows which version we're building. Pass that down instead.
For platforms that weren't having this problem, no functional change
intended. For platforms that were, this simply restores "make package",
so no PKGREVISION bump.
Python 3.8.5 final
Security
bpo-41304: Fixes python3x._pth being ignored on Windows, caused by the fix for bpo-29778 (CVE-2020-15801).
bpo-39603: Prevent http header injection by rejecting control characters in http.client.putrequest(…).
Core and Builtins
bpo-41295: Resolve a regression in CPython 3.8.4 where defining “__setattr__” in a multi-inheritance setup and calling up the hierarchy chain could fail if builtins/extension types were involved in the base types.
Library
bpo-41288: Unpickling invalid NEWOBJ_EX opcode with the C implementation raises now UnpicklingError instead of crashing.
bpo-39017: Avoid infinite loop when reading specially crafted TAR files using the tarfile module (CVE-2019-20907).
Documentation
bpo-37703: Updated Documentation to comprehensively elaborate on the behaviour of gather.cancel()
Build
bpo-41302: Enable building Python 3.8 with libmpdec-2.5.0 to ease maintenance for Linux distributions. Patch by Felix Yan.
macOS
bpo-40741: Update macOS installer to use SQLite 3.32.3.
IDLE
bpo-41300: Save files with non-ascii chars. Fix regression released in 3.9.0b4 and 3.8.4.
Python 3.8.4 final
Security
bpo-41162: Audit hooks are now cleared later during finalization to avoid missing events.
bpo-29778: Ensure python3.dll is loaded from correct locations when Python is embedded (CVE-2020-15523).
Core and Builtins
bpo-41247: Always cache the running loop holder when running asyncio.set_running_loop.
bpo-41252: Fix incorrect refcounting in _ssl.c’s _servername_callback().
bpo-41218: Python 3.8.3 had a regression where compiling with ast.PyCF_ALLOW_TOP_LEVEL_AWAIT would aggressively mark list comprehension with CO_COROUTINE. Now only list comprehension making use of async/await will tagged as so.
bpo-41175: Guard against a NULL pointer dereference within bytearrayobject triggered by the bytearray() + bytearray() operation.
bpo-39960: The “hackcheck” that prevents sneaking around a type’s __setattr__() by calling the superclass method was rewritten to allow C implemented heap types.
Library
bpo-41235: Fix the error handling in ssl.SSLContext.load_dh_params().
bpo-41193: The write_history() atexit function of the readline completer now ignores any OSError to ignore error if the filesystem is read-only, instead of only ignoring FileNotFoundError and PermissionError.
bpo-41043: Fixed the use of glob() in the stdlib: literal part of the path is now always correctly escaped.
bpo-39384: Fixed email.contentmanager to allow set_content() to set a null string.
IDLE
bpo-37765: Add keywords to module name completion list. Rewrite Completions section of IDLE doc.
bpo-41152: The encoding of stdin, stdout and stderr in IDLE is now always UTF-8.
Python 3.8.4 release candidate 1
Security
bpo-41004: The __hash__() methods of ipaddress.IPv4Interface and ipaddress.IPv6Interface incorrectly generated constant hash values of 32 and 128 respectively. This resulted in always causing hash collisions. The fix uses hash() to generate hash values for the tuple of (address, mask length, network address).
bpo-39073: Disallow CR or LF in email.headerregistry.Address arguments to guard against header injection attacks.
Core and Builtins
bpo-41094: Fix decoding errors with audit when open files with non-ASCII names on non-UTF-8 locale.
bpo-41056: Fixes a reference to deallocated stack space during startup when constructing sys.path involving a relative symlink when code was supplied via -c. (discovered via Coverity)
bpo-35975: Stefan Behnel reported that cf_feature_version is used even when PyCF_ONLY_AST is not set. This is against the intention and against the documented behavior, so it’s been fixed.
bpo-40957: Fix refleak in _Py_fopen_obj() when PySys_Audit() fails
bpo-40870: Raise ValueError when validating custom AST’s where the constants True, False and None are used within a ast.Name node.
bpo-40826: Fix GIL usage in PyOS_Readline(): lock the GIL to set an exception and pass the Python thread state when checking if there is a pending signal.
bpo-40824: Unexpected errors in calling the __iter__ method are no longer masked by TypeError in the in operator and functions contains(), indexOf() and countOf() of the operator module.
bpo-40663: Correctly generate annotations where parentheses are omitted but required (e.g: Type[(str, int, *other))].
Library
bpo-41138: Fixed the trace module CLI for Python source files with non-UTF-8 encoding.
bpo-31938: Fix default-value signatures of several functions in the select module - by Anthony Sottile.
bpo-41068: Fixed reading files with non-ASCII names from ZIP archive directly after writing them.
bpo-41058: pdb.find_function() now correctly determines the source file encoding.
bpo-41056: Fix a NULL pointer dereference within the ssl module during a MemoryError in the keylog callback. (discovered by Coverity)
bpo-41048: mimetypes.read_mime_types() function reads the rule file using UTF-8 encoding, not the locale encoding. Patch by Srinivas Reddy Thatiparthy.
bpo-40448: ensurepip now disables the use of pip cache when installing the bundled versions of pip and setuptools. Patch by Krzysztof Konopko.
bpo-40855: The standard deviation and variance functions in the statistics module were ignoring their mu and xbar arguments.
bpo-40807: Stop codeop._maybe_compile, used by code.InteractiveInterpreter (and IDLE). from from emitting each warning three times.
bpo-40834: Fix truncate when sending str object with_xxsubinterpreters.channel_send.
bpo-38488: Update ensurepip to install pip 20.1.1 and setuptools 47.1.0.
bpo-40767: webbrowser now properly finds the default browser in pure Wayland systems by checking the WAYLAND_DISPLAY environment variable. Patch contributed by Jérémy Attali.
bpo-40795: ctypes module: If ctypes fails to convert the result of a callback or if a ctypes callback function raises an exception, sys.unraisablehook is now called with an exception set. Previously, the error was logged into stderr by PyErr_Print().
bpo-30008: Fix ssl code to be compatible with OpenSSL 1.1.x builds that use no-deprecated and --api=1.1.0.
bpo-40614: ast.parse() will not parse self documenting expressions in f-strings when passed feature_version is less than (3, 8).
bpo-40626: Add h5 file extension as MIME Type application/x-hdf5, as per HDF Group recommendation for HDF5 formatted data files. Patch contributed by Mark Schwab.
bpo-25872: linecache could crash with a KeyError when accessed from multiple threads. Fix by Michael Graczyk.
bpo-40597: If text content lines are longer than policy.max_line_length, always use a content-encoding to make sure they are wrapped.
bpo-40515: The ssl and hashlib modules now actively check that OpenSSL is build with thread support. Python 3.7.0 made thread support mandatory and no longer works safely with a no-thread builds.
bpo-13097: ctypes now raises an ArgumentError when a callback is invoked with more than 1024 arguments.
bpo-40457: The ssl module now support OpenSSL builds without TLS 1.0 and 1.1 methods.
bpo-39830: Add zipfile.Path to __all__ in the zipfile module.
bpo-40025: Raise TypeError when _generate_next_value_ is defined after members. Patch by Ethan Onstott.
bpo-39244: Fixed multiprocessing.context.get_all_start_methods to properly return the default method first on macOS.
bpo-39040: Fix parsing of invalid mime headers parameters by collapsing whitespace between encoded words in a bare-quote-string.
bpo-35714: struct.error is now raised if there is a null character in a struct format string.
bpo-36290: AST nodes are now raising TypeError on conflicting keyword arguments. Patch contributed by Rémi Lapeyre.
bpo-29620: assertWarns() no longer raises a RuntimeException when accessing a module’s __warningregistry__ causes importation of a new module, or when a new module is imported in another thread. Patch by Kernc.
bpo-34226: Fix cgi.parse_multipart without content_length. Patch by Roger Duran
Tests
bpo-41085: Fix integer overflow in the array.array.index() method on 64-bit Windows for index larger than 2**31.
bpo-38377: On Linux, skip tests using multiprocessing if the current user cannot create a file in /dev/shm/ directory. Add the skip_if_broken_multiprocessing_synchronize() function to the test.support module.
bpo-41009: Fix use of support.require_{linux|mac|freebsd}_version() decorators as class decorator.
bpo-41003: Fix test_copyreg when numpy is installed: test.pickletester now saves/restores warnings filters when importing numpy, to ignore filters installed by numpy.
bpo-40964: Disable remote imaplib tests, host cyrus.andrew.cmu.edu is blocking incoming connections.
bpo-40055: distutils.tests now saves/restores warnings filters to leave them unchanged. Importing tests imports docutils which imports pkg_resources which adds a warnings filter.
bpo-34401: Make test_gdb properly run on HP-UX. Patch by Michael Osipov.
Build
bpo-40204: Pin Sphinx version to 2.3.1 in Doc/Makefile.
bpo-40653: Move _dirnameW out of HAVE_SYMLINK to fix a potential compiling issue.
Windows
bpo-41074: Fixed support of non-ASCII names in functions msilib.OpenDatabase() and msilib.init_database() and non-ASCII SQL in method msilib.Database.OpenView().
bpo-40164: Updates Windows OpenSSL to 1.1.1g
bpo-39631: Changes the registered MIME type for .py files on Windows to text/x-python instead of text/plain.
bpo-40677: Manually define IO_REPARSE_TAG_APPEXECLINK in case some old Windows SDK doesn’t have it.
bpo-40650: Include winsock2.h in pytime.c for timeval.
bpo-39148: Add IPv6 support to asyncio datagram endpoints in ProactorEventLoop. Change the raised exception for unknown address families to ValueError as it’s not coming from Windows API.
macOS
bpo-39580: Avoid opening Finder window if running installer from the command line. Patch contributed by Rick Heil.
bpo-41100: Fix configure error when building on macOS 11. Note that the current Python release was released shortly after the first developer preview of macOS 11 (Big Sur); there are other known issues with building and running on the developer preview. Big Sur is expected to be fully supported in a future bugfix release of Python 3.8.x and with 3.9.0.
bpo-41005: fixed an XDG settings issue not allowing macos to open browser in webbrowser.py
bpo-40741: Update macOS installer to use SQLite 3.32.2.
IDLE
bpo-41144: Make Open Module open a special module such as os.path.
bpo-39885: Make context menu Cut and Copy work again when right-clicking within a selection.
bpo-40723: Make test_idle pass when run after import.
Tools/Demos
bpo-40479: Update multissltest helper to test with latest OpenSSL 1.0.2, 1.1.0, 1.1.1, and 3.0.0-alpha.
bpo-40163: Fix multissltest tool. OpenSSL has changed download URL for old releases. The multissltest tool now tries to download from current and old download URLs.
Python 3.8.3 final
Core and Builtins
bpo-40527: Fix command line argument parsing: no longer write errors multiple times into stderr.
bpo-40417: Fix imp module deprecation warning when PyImport_ReloadModule is called. Patch by Robert Rouhani.
bpo-39562: The constant values of future flags in the __future__ module are updated in order to prevent collision with compiler flags. Previously PyCF_ALLOW_TOP_LEVEL_AWAIT was clashing with CO_FUTURE_DIVISION.
Library
bpo-40559: Fix possible memory leak in the C implementation of asyncio.Task.
bpo-40355: Improve error reporting in ast.literal_eval() in the presence of malformed ast.Dict nodes instead of silently ignoring any non-conforming elements. Patch by Curtis Bucher.
bpo-40459: platform.win32_ver() now produces correct ptype strings instead of empty strings.
bpo-40398: typing.get_args() now always returns an empty tuple for special generic aliases.
Documentation
bpo-40561: Provide docstrings for webbrowser open functions.
bpo-39435: Fix an incorrect signature for pickle.loads() in the docs
Windows
bpo-40458: Increase reserved stack space to prevent overflow crash on Windows.
C API
bpo-40412: Nullify inittab_copy during finalization, preventing future interpreter initializations in an embedded situation from crashing.
Python 3.8.2 final
Core and Builtins
bpo-39382: Fix a use-after-free in the single inheritance path of issubclass(), when the __bases__ of an object has a single reference, and so does its first item. Patch by Yonatan Goldschmidt.
bpo-39427: Document all possibilities for the -X options in the command line help section. Patch by Pablo Galindo.
Library
bpo-39649: Remove obsolete check for __args__ in bdb.Bdb.format_stack_entry.
bpo-39681: Fix a regression where the C pickle module wouldn’t allow unpickling from a file-like object that doesn’t expose a readinto() method.
bpo-39546: Fix a regression in ArgumentParser where allow_abbrev=False was ignored for long options that used a prefix character other than “-“.
bpo-39432: Implement PEP-489 algorithm for non-ascii “PyInit_…” symbol names in distutils to make it export the correct init symbol also on Windows.
Documentation
bpo-17422: The language reference now specifies restrictions on class namespaces. Adapted from a patch by Ethan Furman.
bpo-39572: Updated documentation of total flag of TypeDict.
bpo-39654: In pyclbr doc, update ‘class’ to ‘module’ where appropriate and add readmodule comment. Patch by Hakan Çelik.
IDLE
bpo-39663: Add tests for pyparse find_good_parse_start().
Python 3.8.1 is the first maintenance release of Python 3.8. The Python 3.8 series is the newest feature release of the Python language, and it contains many new features and optimizations.
Major new features of the 3.8 series, compared to 3.7
PEP 572, Assignment expressions
PEP 570, Positional-only arguments
PEP 587, Python Initialization Configuration (improved embedding)
PEP 590, Vectorcall: a fast calling protocol for CPython
PEP 578, Runtime audit hooks
PEP 574, Pickle protocol 5 with out-of-band data
Typing-related: PEP 591 (Final qualifier), PEP 586 (Literal types), and PEP 589 (TypedDict)
Parallel filesystem cache for compiled bytecode
Debug builds share ABI as release builds
f-strings support a handy = specifier for debugging
continue is now legal in finally: blocks
on Windows, the default asyncio event loop is now ProactorEventLoop
on macOS, the spawn start method is now used by default in multiprocessing
multiprocessing can now use shared memory segments to avoid pickling costs between processes
typed_ast is merged back to CPython
LOAD_GLOBAL is now 40% faster
pickle now uses Protocol 4 by default, improving performance
