Changelog

Python next

Release date: XXXX-XX-XX

Windows

• gh-100180: Update Windows installer to OpenSSL 1.1.1s

Python 3.7.16 final

Release date: 2022-12-06

Security

• gh-100001: python -m http.server no longer allows terminal control characters sent within a garbage request to be printed to the stderr server log.

  This is done by changing the http.server BaseHTTPRequestHandler .log_message method to replace control characters with a \xHH hex escape before printing.

• gh-98433: The IDNA codec decoder used on DNS hostnames by socket or asyncio related name resolution functions no longer involves a quadratic algorithm. This prevents a potential CPU denial of service if an out-of-spec excessive length hostname involving bidirectional characters were decoded. Some protocols such as urllib http 3xx redirects potentially allow for an attacker to supply such a name.

• gh-98739: Update bundled libexpat to 2.5.0

• gh-98517: Port XKCP’s fix for the buffer overflows in SHA-3 (CVE-2022-37454).

• gh-68966: The deprecated mailcap module now refuses to inject unsafe text (filenames, MIME types, parameters) into shell commands. Instead of using such text, it will warn and act as if a match was not found (or for test commands, as if the test failed).

Python 3.7.15 final

Release date: 2022-10-10

Security

• gh-97616: Fix multiplying a list by an integer (list *= int): detect the integer overflow when the new allocated length is close to the maximum size. Issue reported by Jordan Limor. Patch by Victor Stinner.

• gh-97612: Fix a shell code injection vulnerability in the get-remote-certificate.py example script. The script no longer uses a shell to run openssl commands. Issue reported and initial fix by Caleb Shortt. Patch by Victor Stinner.

Core and Builtins

• gh-96848: Fix command line parsing: reject -X int_max_str_digits option with no value (invalid) when the PYTHONINTMAXSTRDIGITS environment variable is set to a valid limit. Patch by Victor Stinner.

• gh-95778: When ValueError is raised if an integer is larger than the limit, mention the sys.set_int_max_str_digits() function in the error message. Patch by Victor Stinner.

Library

• gh-97005: Update bundled libexpat to 2.4.9

Windows

• gh-96577: Fixes a potential buffer overrun in msilib.

Python 3.7.14 final

Release date: 2022-09-06

Security

• gh-95778: Converting between int and str in bases other than 2 (binary), 4, 8 (octal), 16 (hexadecimal), or 32 such as base 10 (decimal) now raises a ValueError if the number of digits in string form is above a limit to avoid potential denial of service attacks due to the algorithmic complexity. This is a mitigation for CVE-2020-10735.

  This new limit can be configured or disabled by environment variable, command line flag, or sys APIs. See the integer string conversion length limitation documentation. The default limit is 4300 digits in string form.

  Patch by Gregory P. Smith [Google] and Christian Heimes [Red Hat] with feedback from Victor Stinner, Thomas Wouters, Steve Dower, Ned Deily, and Mark Dickinson.

• gh-87389: http.server: Fix an open redirection vulnerability in the HTTP server when an URI path starts with //. Vulnerability discovered, and initial fix proposed, by Hamza Avvan.

Core and Builtins

• gh-93065: Fix contextvars HAMT implementation to handle iteration over deep trees.

  The bug was discovered and fixed by Eli Libman. See MagicStack/immutables#84 for more details.

Library

• bpo-36073: Raise ProgrammingError instead of segfaulting on recursive usage of cursors in sqlite3 converters. Patch by Sergey Fedoseev.

Documentation

• gh-91888: Add a new gh role to the documentation to link to GitHub issues.

• bpo-47138: Pin Jinja to a version compatible with Sphinx version 2.3.1.

Tests

• gh-94208: test_ssl is now checking for supported TLS version and protocols in more tests.

• bpo-47016: Create a GitHub Actions workflow for verifying bundled pip and setuptools. Patch by Illia Volochii and Adam Turner.

• bpo-41306: Fixed a failure in test_tk.test_widgets.ScaleTest happening when executing the test with Tk 8.6.10.

Windows

• bpo-47194: Update zlib to v1.2.12 to resolve CVE-2018-25032.

Python 3.7.13 final

Release date: 2022-03-16

Library

• bpo-46985: Upgrade pip wheel bundled with ensurepip (pip 22.0.4)

• bpo-46932: Update bundled libexpat to 2.4.7

• bpo-46811: Make test suite support Expat >=2.4.5

• bpo-46784: Fix libexpat symbols collisions with user dynamically loaded or statically linked libexpat in embedded Python.

• bpo-46756: Fix a bug in urllib.request.HTTPPasswordMgr.find_user_password() and urllib.request.HTTPPasswordMgrWithPriorAuth.is_authenticated() which allowed to bypass authorization. For example, access to URI example.org/foobar was allowed if the user was authorized for URI example.org/foo.

Build

• bpo-47024: Update Windows builds and macOS installer build to use OpenSSL 1.1.1n.

• bpo-45405: Prevent internal configure error when running configure with recent versions of clang. Patch by David Bohman.

Windows

• bpo-44549: Update bzip2 to 1.0.8 in Windows builds to mitigate CVE-2016-3189 and CVE-2019-12900

• bpo-46948: Prevent CVE-2022-26488 by ensuring the Add to PATH option in the Windows installer uses the correct path when being repaired.

Python 3.7.12 final

Release date: 2021-09-03

Security

• bpo-44394: Update the vendored copy of libexpat to 2.4.1 (from 2.2.8) to get the fix for the CVE-2013-0340 “Billion Laughs” vulnerability. This copy is most used on Windows and macOS.

• bpo-43124: Made the internal putcmd function in smtplib sanitize input for presence of \r and \n characters to avoid (unlikely) command injection.

Library

• bpo-45001: Made email date parsing more robust against malformed input, namely a whitespace-only Date: header. Patch by Wouter Bolsterlee.

Python 3.7.11 final

Release date: 2021-06-28

Security

• bpo-44022: http.client now avoids infinitely reading potential HTTP headers after a 100 Continue status response from the server.

• bpo-43882: The presence of newline or tab characters in parts of a URL could allow some forms of attacks.

  Following the controlling specification for URLs defined by WHATWG urllib.parse() now removes ASCII newlines and tabs from URLs, preventing such attacks.

• bpo-42988: CVE-2021-3426: Remove the getfile feature of the pydoc module which could be abused to read arbitrary files on the disk (directory traversal vulnerability). Moreover, even source code of Python modules can contain sensitive data like passwords. Vulnerability reported by David Schwörer.

• bpo-43285: ftplib no longer trusts the IP address value returned from the server in response to the PASV command by default. This prevents a malicious FTP server from using the response to probe IPv4 address and port combinations on the client network.

  Code that requires the former vulnerable behavior may set a trust_server_pasv_ipv4_address attribute on their ftplib.FTP instances to True to re-enable it.

• bpo-43075: Fix Regular Expression Denial of Service (ReDoS) vulnerability in urllib.request.AbstractBasicAuthHandler. The ReDoS-vulnerable regex has quadratic worst-case complexity and it allows cause a denial of service when identifying crafted invalid RFCs. This ReDoS issue is on the client side and needs remote attackers to control the HTTP server.

Core and Builtins

• bpo-43660: Fix crash that happens when replacing sys.stderr with a callable that can remove the object while an exception is being printed. Patch by Pablo Galindo.

Tests

• bpo-41561: Add workaround for Ubuntu’s custom OpenSSL security level policy.

Python 3.7.10 final

Release date: 2021-02-15

Security

• bpo-42967: Fix web cache poisoning vulnerability by defaulting the query args separator to &, and allowing the user to choose a custom separator.

• bpo-42938: Avoid static buffers when computing the repr of ctypes.c_double and ctypes.c_longdouble values.

• bpo-42103: Prevented potential DoS attack via CPU and RAM exhaustion when processing malformed Apple Property List files in binary format.

• bpo-42051: The plistlib module no longer accepts entity declarations in XML plist files to avoid XML vulnerabilities. This should not affect users as entity declarations are not used in regular plist files.

• bpo-40791: Add volatile to the accumulator variable in hmac.compare_digest, making constant-time-defeating optimizations less likely.

Library

• bpo-42103: InvalidFileException and RecursionError are now the only errors caused by loading malformed binary Plist file (previously ValueError and TypeError could be raised in some specific cases).

• bpo-41976: Fixed a bug that was causing ctypes.util.find_library() to return None when triying to locate a library in an environment when gcc>=9 is available and ldconfig is not. Patch by Pablo Galindo

Documentation

• bpo-17140: Add documentation for the multiprocessing.pool.ThreadPool class.

Tests

• bpo-42794: Update test_nntplib to use offical group name of news.aioe.org for testing. Patch by Dong-hee Na.

• bpo-41944: Tests for CJK codecs no longer call eval() on content received via HTTP.

Python 3.7.9 final

Release date: 2020-08-15

Security

• bpo-41304: Fixes python3x._pth being ignored on Windows, caused by the fix for bpo-29778 (CVE-2020-15801).

• bpo-29778: Ensure python3.dll is loaded from correct locations when Python is embedded (CVE-2020-15523).

• bpo-41004: CVE-2020-14422: 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-39603: Prevent http header injection by rejecting control characters in http.client.putrequest(…).

Core and Builtins

• bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() correctly

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).

• bpo-41235: Fix the error handling in ssl.SSLContext.load_dh_params().

macOS

• bpo-41100: Additional fixes for testing on macOS 11 Big Sur Intel. Note: macOS 11 is not yet released, this release of Python is not fully supported on 11.0, and not all tests pass.

Python 3.7.8 final

Release date: 2020-06-27

Tests

• bpo-41009: Fix use of support.require_{linux|mac|freebsd}_version() decorators as class decorator.

macOS

• bpo-41100: Fix configure error when building on macOS 11. Note that 3.7.8 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.

Python 3.7.8 release candidate 1

Release date: 2020-06-17

Security

• bpo-39073: Disallow CR or LF in email.headerregistry.Address arguments to guard against header injection attacks.

• bpo-38576: Disallow control characters in hostnames in http.client, addressing CVE-2019-18348. Such potentially malicious header injection URLs now cause a InvalidURL to be raised.

• bpo-39503: CVE-2020-8492: The AbstractBasicAuthHandler class of the urllib.request module uses an inefficient regular expression which can be exploited by an attacker to cause a denial of service. Fix the regex to prevent the catastrophic backtracking. Vulnerability reported by Ben Caller and Matt Schwager.

Core and Builtins

• bpo-40663: Correctly generate annotations where parentheses are omitted but required (e.g: Type[(str, int, *other))].

• bpo-40417: Fix imp module deprecation warning when PyImport_ReloadModule is called. Patch by Robert Rouhani.

• bpo-20526: Fix PyThreadState_Clear(). PyThreadState.frame is a borrowed reference, not a strong reference: PyThreadState_Clear() must not call Py_CLEAR(tstate->frame).

• bpo-38894: Fix a bug that was causing incomplete results when calling pathlib.Path.glob in the presence of symlinks that point to files where the user does not have read access. Patch by Pablo Galindo and Matt Wozniski.

• bpo-39871: Fix a possible SystemError in math.{atan2,copysign,remainder}() when the first argument cannot be converted to a float. Patch by Zachary Spytz.

• bpo-39520: Fix unparsing of ext slices with no items (foo[:,]). Patch by Batuhan Taskaya.

• bpo-24048: Save the live exception during import.c’s remove_module().

• bpo-22490: Don’t leak environment variable __PYVENV_LAUNCHER__ into the interpreter session on macOS.

Library

• bpo-40448: ensurepip now disables the use of pip cache when installing the bundled versions of pip and setuptools. Patch by Krzysztof Konopko.

• bpo-40807: Stop codeop._maybe_compile, used by code.InteractiveInterpreter (and IDLE). from from emitting each warning three times.

• 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-30008: Fix ssl code to be compatible with OpenSSL 1.1.x builds that use no-deprecated and --api=1.1.0.

• bpo-25872: linecache could crash with a KeyError when accessed from multiple threads. Fix by Michael Graczyk.

• 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-40559: Fix possible memory leak in the C implementation of asyncio.Task.

• bpo-40457: The ssl module now support OpenSSL builds without TLS 1.0 and 1.1 methods.

• bpo-40459: platform.win32_ver() now produces correct ptype strings instead of empty strings.

• bpo-40138: Fix the Windows implementation of os.waitpid() for exit code larger than INT_MAX >> 8. The exit status is now interpreted as an unsigned number.

• bpo-39942: Set “__main__” as the default module name when “__name__” is missing in typing.TypeVar. Patch by Weipeng Hong.

• bpo-40287: Fixed SpooledTemporaryFile.seek() to return the position.

• bpo-40196: Fix a bug in the symtable module that was causing incorrectly report global variables as local. Patch by Pablo Galindo.

• bpo-40126: Fixed reverting multiple patches in unittest.mock. Patcher’s __exit__() is now never called if its __enter__() is failed. Returning true from __exit__() silences now the exception.

• bpo-40089: Fix threading._after_fork(): if fork was not called by a thread spawned by threading.Thread, threading._after_fork() now creates a _MainThread instance for _main_thread, instead of a _DummyThread instance.

• bpo-39503: AbstractBasicAuthHandler of urllib.request now parses all WWW-Authenticate HTTP headers and accepts multiple challenges per header: use the realm of the first Basic challenge.

• bpo-40014: Fix os.getgrouplist(): if getgrouplist() function fails because the group list is too small, retry with a larger group list. On failure, the glibc implementation of getgrouplist() sets ngroups to the total number of groups. For other implementations, double the group list size.

• bpo-40025: Raise TypeError when _generate_next_value_ is defined after members. Patch by Ethan Onstott.

• bpo-40016: In re docstring, clarify the relationship between inline and argument compile flags.

• bpo-39652: The column name found in sqlite3.Cursor.description is now truncated on the first ‘[’ only if the PARSE_COLNAMES option is set.

• bpo-38662: The ensurepip module now invokes pip via the runpy module. Hence it is no longer tightly coupled with the internal API of the bundled pip version, allowing easier updates to a newer pip version both internally and for distributors.

• bpo-39916: More reliable use of os.scandir() in Path.glob(). It no longer emits a ResourceWarning when interrupted.

• bpo-39850: multiprocessing now supports abstract socket addresses (if abstract sockets are supported in the running platform). Patch by Pablo Galindo.

• bpo-39828: Fix json.tool to catch BrokenPipeError. Patch by Dong-hee Na.

• 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-36541: lib2to3 now recognizes named assignment expressions (the walrus operator, :=)

• 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

• bpo-31758: Prevent crashes when using an uninitialized _elementtree.XMLParser object. Patch by Oren Milman.

Documentation

• bpo-40561: Provide docstrings for webbrowser open functions.

• bpo-27635: The pickle documentation incorrectly claimed that __new__ isn’t called by default when unpickling.

• bpo-39879: Updated Data model docs to include dict() insertion order preservation. Patch by Furkan Onder and Samy Lahfa.

• bpo-39677: Changed operand name of MAKE_FUNCTION from argc to flags for module dis

• bpo-39435: Fix an incorrect signature for pickle.loads() in the docs

• bpo-38387: Document PyDoc_STRVAR macro in the C-API reference.

Tests

• 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-40436: test_gdb and test.pythoninfo now check gdb command exit code.

• bpo-39932: Fix multiprocessing test_heap(): a new Heap object is now created for each test run.

• bpo-40162: Update Travis CI configuration to OpenSSL 1.1.1f.

• bpo-40146: Update OpenSSL to 1.1.1f in Azure Pipelines.

• bpo-40019: test_gdb now skips tests if it detects that gdb failed to read debug information because the Python binary is optimized.

• bpo-27807: test_site.test_startup_imports() is now skipped if a path of sys.path contains a .pth file.

• bpo-39793: Use the same domain when testing make_msgid. Patch by Batuhan Taskaya.

• bpo-1812: Fix newline handling in doctest.testfile when loading from a package whose loader has a get_data method. Patch by Peter Donis.

• bpo-37957: test.regrtest now can receive a list of test patterns to ignore (using the -i/–ignore argument) or a file with a list of patterns to ignore (using the –ignore-file argument). Patch by Pablo Galindo.

• bpo-38502: test.regrtest now uses process groups in the multiprocessing mode (-jN command line option) if process groups are available: if os.setsid() and os.killpg() functions are available.

• bpo-37421: multiprocessing tests now stop the ForkServer instance if it’s running: close the “alive” file descriptor to ask the server to stop and then remove its UNIX address.

• bpo-37421: multiprocessing tests now explicitly call _run_finalizers() to immediately remove temporary directories created by tests.

Build

• bpo-40653: Move _dirnameW out of HAVE_SYMLINK to fix a potential compiling issue.

• bpo-38360: Support single-argument form of macOS -isysroot flag.

• bpo-40204: Pin Sphinx version to 2.3.1 in Doc/Makefile.

• bpo-40158: Fix CPython MSBuild Properties in NuGet Package (build/native/python.props)

Windows

• 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-40650: Include winsock2.h in pytime.c for timeval.

• bpo-39930: Ensures the required vcruntime140.dll is included in install packages.

• bpo-39847: Avoid hang when computer is hibernated whilst waiting for a mutex (for lock-related objects from threading) around 49-day uptime.

• bpo-38492: Remove pythonw.exe dependency on the Microsoft C++ runtime.

macOS

• bpo-39580: Avoid opening Finder window if running installer from the command line.

• bpo-40400: Update the macOS installer build scripts to build with Python 3.x and to build correctly on newer macOS systems with SIP.

• bpo-40741: Update macOS installer to use SQLite 3.32.2.

• bpo-38329: python.org macOS installers now update the Current version symlink of /Library/Frameworks/Python.framework/Versions for 3.9 installs. Previously, Current was only updated for Python 2.x installs. This should make it easier to embed Python 3 into other macOS applications.

• bpo-40164: Update macOS installer builds to use OpenSSL 1.1.1g.

IDLE

• 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.

• bpo-27115: For ‘Go to Line’, use a Query box subclass with IDLE standard behavior and improved error checking.

• bpo-39885: Since clicking to get an IDLE context menu moves the cursor, any text selection should be and now is cleared.

• bpo-39852: Edit “Go to line” now clears any selection, preventing accidental deletion. It also updates Ln and Col on the status bar.

• bpo-38439: Add a 256×256 pixel IDLE icon to support more modern environments. Created by Andrew Clover. Delete the unused macOS idle.icns icon file.

• bpo-38689: IDLE will no longer freeze when inspect.signature fails when fetching a calltip.

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-40179: Fixed translation of #elif in Argument Clinic.

• 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.

• bpo-36184: Port python-gdb.py to FreeBSD. python-gdb.py now checks for “take_gil” function name to check if a frame tries to acquire the GIL, instead of checking for “pthread_cond_timedwait” which is specific to Linux and can be a different condition than the GIL.

• bpo-39889: Fixed unparse.py for extended slices containing a single element (e.g. a[i:j,]). Remove redundant tuples when index with a tuple (e.g. a[i, j]).

C API

• bpo-39884: _PyMethodDef_RawFastCallDict() and _PyMethodDef_RawFastCallKeywords() now include the method name in the SystemError “bad call flags” error message to ease debug.

• bpo-38643: PyNumber_ToBase() now raises a SystemError instead of crashing when called with invalid base.

Python 3.7.7 final

Release date: 2020-03-10

Library

• bpo-13487: Avoid a possible “RuntimeError: dictionary changed size during iteration” from inspect.getmodule() when it tried to loop through sys.modules.

Documentation

• bpo-17422: The language reference no longer restricts default class namespaces to dicts only.

Python 3.7.7 release candidate 1

Release date: 2020-03-04

Security

• bpo-39401: Avoid unsafe load of api-ms-win-core-path-l1-1-0.dll at startup on Windows 7.

Core and Builtins

• bpo-39776: Fix race condition where threads created by PyGILState_Ensure() could get a duplicate id.

  This affects consumers of tstate->id like the contextvar caching machinery, which could return invalid cached objects under heavy thread load (observed in embedded scenarios).

• bpo-39778: Fixed a crash due to incorrect handling of weak references in collections.OrderedDict classes. Patch by Pablo Galindo.

• 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-39606: Fix regression caused by fix for bpo-39386, that prevented calling aclose on an async generator that had already been closed or exhausted.

• bpo-39510: Fix segfault in readinto() method on closed BufferedReader.

• bpo-39453: Fixed a possible crash in list.__contains__() when a list is changed during comparing items. Patch by Dong-hee Na.

• bpo-39427: Document all possibilities for the -X options in the command line help section. Patch by Pablo Galindo.

• bpo-39421: Fix possible crashes when operating with the functions in the heapq module and custom comparison operators.

• bpo-39386: Prevent double awaiting of async iterator.

• bpo-38588: Fix possible crashes in dict and list when calling PyObject_RichCompareBool().

• bpo-39031: When parsing an “elif” node, lineno and col_offset of the node now point to the “elif” keyword and not to its condition, making it consistent with the “if” node. Patch by Lysandros Nikolaou.

• bpo-38610: Fix possible crashes in several list methods by holding strong references to list elements when calling PyObject_RichCompareBool().

Library

• bpo-39794: Add –without-decimal-contextvar build option. This enables a thread-local rather than a coroutine local context.

• bpo-39769: The compileall.compile_dir() function’s ddir parameter and the compileall command line flag -d no longer write the wrong pathname to the generated pyc file for submodules beneath the root of the directory tree being compiled. This fixes a regression introduced with Python 3.5.

• bpo-30566: Fix IndexError when trying to decode an invalid string with punycode codec.

• bpo-39649: Remove obsolete check for __args__ in bdb.Bdb.format_stack_entry.

• bpo-27657: The original fix for bpo-27657, “Fix urlparse() with numeric paths” (PR 16839) included in 3.7.6, inadvertently introduced a behavior change that broke several third-party packages relying on the original undefined parsing behavior. The change is reverted in 3.7.7, restoring the behavior of 3.7.5 and earlier releases.

• bpo-21016: The pydoc and trace modules now use the sysconfig module to get the path to the Python standard library, to support uncommon installation path like /usr/lib64/python3.9/ on Fedora. Patch by Jan Matějek.

• bpo-39548: Fix handling of header in urllib.request.AbstractDigestAuthHandler when the optional qop parameter is not present.

• bpo-39450: Striped whitespace from docstring before returning it from unittest.case.shortDescription().

• bpo-39493: Mark typing.IO.closed as a property

• bpo-39485: Fix a bug in unittest.mock.create_autospec() that would complain about the wrong number of arguments for custom descriptors defined in an extension module returning functions.

• bpo-39430: Fixed race condition in lazy imports in tarfile.

• bpo-39389: Write accurate compression level metadata in gzip archives, rather than always signaling maximum compression.

• bpo-39274: bool(fraction.Fraction) now returns a boolean even if (numerator != 0) does not return a boolean (ex: numpy number).

• bpo-39242: Updated the Gmane domain from news.gmane.org to news.gmane.io which is used for examples of NNTP news reader server and nntplib tests.

• bpo-39152: Fix ttk.Scale.configure([name]) to return configuration tuple for name or all options. Giovanni Lombardo contributed part of the patch.

• bpo-39198: If an exception were to be thrown in Logger.isEnabledFor (say, by asyncio timeouts or stopit) , the logging global lock may not be released appropriately, resulting in deadlock. This change wraps that block of code with try...finally to ensure the lock is released.

• bpo-39191: Perform a check for running loop before starting a new task in loop.run_until_complete() to fail fast; it prevents the side effect of new task spawning before exception raising.

• bpo-38871: Correctly parenthesize filter-based statements that contain lambda expressions in mod:lib2to3. Patch by Dong-hee Na.

• bpo-39142: A change was made to logging.config.dictConfig to avoid converting instances of named tuples to ConvertingTuple. It’s assumed that named tuples are too specialised to be treated like ordinary tuples; if a user of named tuples requires ConvertingTuple functionality, they will have to implement that themselves in their named tuple class.

• bpo-38971: Open issue in the BPO indicated a desire to make the implementation of codecs.open() at parity with io.open(), which implements a try/except to assure file stream gets closed before an exception is raised.

• bpo-39057: urllib.request.proxy_bypass_environment() now ignores leading dots and no longer ignores a trailing newline.

• bpo-39056: Fixed handling invalid warning category in the -W option. No longer import the re module if it is not needed.

• bpo-39055: base64.b64decode() with validate=True raises now a binascii.Error if the input ends with a single \n.

• bpo-38878: Fixed __subclasshook__ of os.PathLike to return a correct result upon inheritence. Patch by Bar Harel.

• bpo-35182: Fixed Popen.communicate() subsequent call crash when the child process has already closed any piped standard stream, but still continues to be running. Patch by Andriy Maletsky.

• bpo-38473: Use signature from inner mock for autospecced methods attached with unittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.

• bpo-38293: Add copy.copy() and copy.deepcopy() support to property() objects.

• bpo-37953: In typing, improved the __hash__ and __eq__ methods for ForwardReferences.

• bpo-36406: Handle namespace packages in doctest. Patch by Karthikeyan Singaravelan.

Documentation

• bpo-13790: Change ‘string’ to ‘specification’ in format doc.

• bpo-39530: Fix misleading documentation about mixed-type numeric comparisons.

• bpo-17422: The language reference now specifies restrictions on class namespaces. Adapted from a patch by Ethan Furman.

• bpo-39654: In pyclbr doc, update ‘class’ to ‘module’ where appropriate and add readmodule comment. Patch by Hakan Çelik.

• bpo-39392: Explain that when filling with turtle, overlap regions may be left unfilled.

• bpo-39381: Mention in docs that asyncio.get_event_loop() implicitly creates new event loop only if called from the main thread.

• bpo-38918: Add an entry for __module__ in the “function” & “method” sections of the inspect docs types and members table

• bpo-3530: In the ast module documentation, fix a misleading NodeTransformer example and add advice on when to use the fix_missing_locations function.

Tests

• bpo-38546: Fix test_ressources_gced_in_workers() of test_concurrent_futures: explicitly stop the manager to prevent leaking a child process running in the background after the test completes.

Build

• bpo-39144: The ctags and etags build targets both include Modules/_ctypes and Python standard library source files.

Windows

• bpo-38597: distutils will no longer statically link vcruntime140.dll when a redistributable version is unavailable. All future releases of CPython will include a copy of this DLL to ensure distributed extensions can continue to load.

• bpo-38380: Update Windows builds to use SQLite 3.31.1

• bpo-39439: Reduce overhead when using multiprocessing in a Windows virtual environment

• bpo-39185: The build.bat script has additional options for very-quiet output (-q) and very-verbose output (-vv)

macOS

• bpo-38380: Update macOS builds to use SQLite 3.31.1

IDLE

• bpo-39781: Selecting code context lines no longer causes a jump.

• bpo-39663: Add tests for pyparse find_good_parse_start().

• bpo-39600: In the font configuration window, remove duplicated font names.

• bpo-30780: Add remaining configdialog tests for buttons and highlights and keys tabs.

• bpo-39388: IDLE Settings Cancel button now cancels pending changes

• bpo-39050: Make IDLE Settings dialog Help button work again.

• bpo-34118: Tag memoryview, range, and tuple as classes, the same as list, etcetera, in the library manual built-in functions list.

• bpo-38792: Close an IDLE shell calltip if a KeyboardInterrupt or shell restart occurs. Patch by Zackery Spytz.

• bpo-32989: Add tests for editor newline_and_indent_event method. Remove dead code from pyparse find_good_parse_start method.

Python 3.7.6 final

Release date: 2019-12-18

macOS

• bpo-38295: Prevent failure of test_relative_path in test_py_compile on macOS Catalina.

Python 3.7.6 release candidate 1

Release date: 2019-12-11

Security

• bpo-38945: Newline characters have been escaped when performing uu encoding to prevent them from overflowing into to content section of the encoded file. This prevents malicious or accidental modification of data during the decoding process.

• bpo-37228: 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 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.)

• bpo-38804: Fixes a ReDoS vulnerability in http.cookiejar. Patch by Ben Caller.

Core and Builtins

• bpo-38673: In REPL mode, don’t switch to PS2 if the line starts with comment or whitespace. Based on work by Batuhan Taşkaya.

• bpo-38535: Fixed line numbers and column offsets for AST nodes for calls without arguments in decorators.

• bpo-38379: When cyclic garbage collection (gc) runs finalizers that resurrect unreachable objects, the current gc run ends, without collecting any cyclic trash. However, the statistics reported by collect() and get_stats() claimed that all cyclic trash found was collected, and that the resurrected objects were collected. Changed the stats to report that none were collected.

• bpo-35409: Ignore GeneratorExit exceptions when throwing an exception into the aclose coroutine of an asynchronous generator.

Library

• bpo-39006: Fix asyncio when the ssl module is missing: only check for ssl.SSLSocket instance if the ssl module is available.

• bpo-38979: Return class from ContextVar.__class_getitem__ to simplify subclassing.

• bpo-38986: Make repr of C accelerated TaskWakeupMethWrapper the same as of pure Python version.

• bpo-33684: Fix json.tool failed to read a JSON file with non-ASCII characters when locale encoding is not UTF-8.

• bpo-26730: Fix SpooledTemporaryFile.rollover() might corrupt the file when it is in text mode. Patch by Serhiy Storchaka.

• bpo-37838: typing.get_type_hints() properly handles functions decorated with functools.wraps().

• bpo-38821: Fix unhandled exceptions in argparse when internationalizing error messages for arguments with nargs set to special (non-integer) values. Patch by Federico Bond.

• bpo-38820: Make Python compatible with OpenSSL 3.0.0. ssl.SSLSocket.getpeercert() no longer returns IPv6 addresses with a trailing new line.

• bpo-38785: Prevent asyncio from crashing if parent __init__ is not called from a constructor of object derived from asyncio.Future.

• bpo-27805: Allow opening pipes and other non-seekable files in append mode with open().

• bpo-38686: Added support for multiple qop values in urllib.request.AbstractDigestAuthHandler.

• bpo-38334: Fixed seeking backward on an encrypted zipfile.ZipExtFile.

• bpo-31202: The case the result of pathlib.WindowsPath.glob() matches now the case of the pattern for literal parts.

• bpo-38109: Add missing stat.S_IFDOOR, stat.S_IFPORT, stat.S_IFWHT, stat.S_ISDOOR(), stat.S_ISPORT(), and stat.S_ISWHT() values to the Python implementation of stat.

• bpo-38422: Clarify docstrings of pathlib suffix(es)

• bpo-38405: Nested subclasses of typing.NamedTuple are now pickleable.

• bpo-38332: Prevent KeyError thrown by _encoded_words.decode() when given an encoded-word with invalid content-type encoding from propagating all the way to email.message.get().

• bpo-38341: Add smtplib.SMTPNotSupportedError to the smtplib exported names.

• bpo-13153: OS native encoding is now used for converting between Python strings and Tcl objects. This allows to display, copy and paste to clipboard emoji and other non-BMP characters. Converting strings from Tcl to Python and back now never fails (except MemoryError).

• bpo-36993: Improve error reporting for corrupt zip files with bad zip64 extra data. Patch by Daniel Hillier.

• bpo-36952: Starting with Python 3.3, importing ABCs from collections is deprecated, and import should be done from collections.abc. Still being able to import from collections was marked for removal in 3.8, but has been delayed to 3.9; documentation and DeprecationWarning clarified.

• bpo-36820: Break cycle generated when saving an exception in socket.py, codeop.py and dyld.py as they keep alive not only the exception but user objects through the __traceback__ attribute. Patch by Mario Corchero.

• bpo-34776: Fix dataclasses to support forward references in type annotations

• bpo-33348: lib2to3 now recognizes expressions after * and ** like in f(*[] or []).

• bpo-27657: Fix urllib.parse.urlparse() with numeric paths. A string like “path:80” is no longer parsed as a path but as a scheme (“path”) and a path (“80”).

Documentation

• bpo-38351: Modernize email examples from %-formatting to f-strings.

• bpo-38592: Add Brazilian Portuguese to the language switcher at Python Documentation website.

• bpo-38294: Add list of no-longer-escaped chars to re.escape documentation

Tests

• bpo-38547: Fix test_pty: if the process is the session leader, closing the master file descriptor raises a SIGHUP signal: simply ignore SIGHUP when running the tests.

• bpo-38965: Fix test_faulthandler on GCC 10. Use the “volatile” keyword in faulthandler._stack_overflow() to prevent tail call optimization on any compiler, rather than relying on compiler specific pragma.

• bpo-38669: Raise TypeError when passing target as a string with unittest.mock.patch.object().

• bpo-35998: Fix a race condition in test_asyncio.test_start_tls_server_1(). Previously, there was a race condition between the test main() function which replaces the protocol and the test ServerProto protocol which sends ANSWER once it gets HELLO. Now, only the test main() function is responsible to send data, ServerProto no longer sends data.

• bpo-37531: On timeout, regrtest no longer attempts to call popen.communicate() again: it can hang until all child processes using stdout and stderr pipes completes. Kill the worker process and ignores its output. Change also the faulthandler timeout of the main process from 1 minute to 5 minutes, for Python slowest buildbots.

Build

• bpo-37404: asyncio now raises TyperError when calling incompatible methods with an ssl.SSLSocket socket. Patch by Ido Michael.

• bpo-38809: On Windows, build scripts will now recognize and use python.exe from an active virtual env.

• bpo-37415: Fix stdatomic.h header check for ICC compiler: the ICC implementation lacks atomic_uintptr_t type which is needed by Python.

Windows

• bpo-38589: Fixes HTML Help shortcut when Windows is not installed to C drive

IDLE

• bpo-38944: Excape key now closes IDLE completion windows. Patch by Johnny Najera.

• bpo-38943: Fix IDLE autocomplete windows not always appearing on some systems. Patch by Johnny Najera.

• bpo-38862: ‘Strip Trailing Whitespace’ on the Format menu removes extra newlines at the end of non-shell files.

• bpo-26353: Stop adding newline when saving an IDLE shell window.

• bpo-38636: Fix IDLE Format menu tab toggle and file indent width. These functions (default shortcuts Alt-T and Alt-U) were mistakenly disabled in 3.7.5 and 3.8.0.

• bpo-4630: Add an option to toggle IDLE’s cursor blink for shell, editor, and output windows. See Settings, General, Window Preferences, Cursor Blink. Patch by Zachary Spytz.

• bpo-38598: Do not try to compile IDLE shell or output windows

• bpo-36698: IDLE no longer fails when write non-encodable characters to stderr. It now escapes them with a backslash, as the regular Python interpreter. Added the errors field to the standard streams.

Tools/Demos

• bpo-38118: Update Valgrind suppression file to ignore a false alarm in PyUnicode_Decode() when using GCC builtin strcmp().

• bpo-38347: pathfix.py: Assume all files that end on ‘.py’ are Python scripts when working recursively.

C API

• bpo-38540: Fixed possible leak in PyArg_Parse() and similar functions for format units "es#" and "et#" when the macro PY_SSIZE_T_CLEAN is not defined.

• bpo-38395: Fix a crash in weakref.proxy objects due to incorrect lifetime management when calling some associated methods that may delete the last reference to object being referenced by the proxy. Patch by Pablo Galindo.

Python 3.7.5 final

Release date: 2019-10-14

Library

• bpo-38368: Prevent ctypes crash when handling arrays in structs/unions.

• bpo-38449: Revert PR 15522, which introduces a regression in mimetypes.guess_type() due to improper handling of filenames as urls.

Windows

• bpo-38344: Fix syntax in activate.bat.

Python 3.7.5 release candidate 1

Release date: 2019-10-01

Security

• bpo-38243: Escape the server title of xmlrpc.server.DocXMLRPCServer when rendering the document page as HTML. (Contributed by Dong-hee Na in bpo-38243.)

• bpo-38174: Update vendorized expat library version to 2.2.8, which resolves CVE-2019-15903.

• bpo-37764: Fixes email._header_value_parser.get_unstructured going into an infinite loop for a specific case in which the email header does not have trailing whitespace, and the case in which it contains an invalid encoded word. Patch by Ashwin Ramaswami.

• bpo-37461: Fix an infinite loop when parsing specially crafted email headers. Patch by Abhilash Raj.

• bpo-34155: Fix parsing of invalid email addresses with more than one @ (e.g. a@b@c.com.) to not return the part before 2nd @ as valid email address. Patch by maxking & jpic.

Core and Builtins

• bpo-36871: Improve error handling for the assert_has_calls method of mocks. Fixed a bug where any errors encountered while binding the expected calls to the mock’s spec were silently swallowed, leading to misleading error output.

• bpo-38013: Allow to call async_generator_athrow().throw(...) even for non-started async generator helper. It fixes annoying warning at the end of asyncio.run() call.

• bpo-38124: Fix an off-by-one error in PyState_AddModule that could cause out-of-bounds memory access.

• bpo-36946: Fix possible signed integer overflow when handling slices. Patch by hongweipeng.

• bpo-37409: Ensure explicit relative imports from interactive sessions and scripts (having no parent package) always raise ImportError, rather than treating the current module as the package. Patch by Ben Lewis.

• bpo-36311: Decoding bytes objects larger than 2GiB is faster and no longer fails when a multibyte characters spans a chunk boundary.

• bpo-37467: Fix sys.excepthook() and PyErr_Display() if a filename is a bytes string. For example, for a SyntaxError exception where the filename attribute is a bytes string.

• bpo-37417: bytearray.extend() now correctly handles errors that arise during iteration. Patch by Brandt Bucher.

• bpo-20523: pdb.Pdb supports ~/.pdbrc in Windows 7. Patch by Tim Hopper and Dan Lidral-Porter.

Library

• bpo-38019: Correctly handle pause/resume reading of closed asyncio unix pipe.

• bpo-38216: Allow the rare code that wants to send invalid http requests from the http.client library a way to do so. The fixes for bpo-30458 led to breakage for some projects that were relying on this ability to test their own behavior in the face of bad requests.

• bpo-38191: Constructor of NamedTuple type now accepts arbitrary keyword argument names, including “cls”, “self”, “typename” and “fields”.

• bpo-38185: Fixed case-insensitive string comparison in sqlite3.Row indexing.

• bpo-38175: Fix a memory leak in comparison of sqlite3.Row objects.

• bpo-33936: _hashlib no longer calls obsolete OpenSSL initialization function with OpenSSL 1.1.0+.

• bpo-34706: Preserve subclassing in inspect.Signature.from_callable.

• bpo-38059: inspect.py now uses sys.exit() instead of exit()

• bpo-38006: weakref.WeakValueDictionary defines a local remove() function used as callback for weak references. This function was created with a closure. Modify the implementation to avoid the closure.

• bpo-34410: Fixed a crash in the tee() iterator when re-enter it. RuntimeError is now raised in this case.

• bpo-37965: Fix C compiler warning caused by distutils.ccompiler.CCompiler.has_function.

• bpo-36205: Fix the rusage implementation of time.process_time() to correctly report the sum of the system and user CPU time.

• bpo-22347: Update mimetypes.guess_type to allow proper parsing of URLs with only a host name. Patch by Dong-hee Na.

• bpo-37950: Fix ast.dump() when call with incompletely initialized node.

• bpo-37915: Fix a segmentation fault that appeared when comparing instances of datetime.timezone and datetime.tzinfo objects. Patch by Pablo Galindo.

• bpo-37885: venv: Don’t generate unset variable warning on deactivate.

• bpo-37868: Fix dataclasses.is_dataclass when given an instance that never raises AttributeError in __getattr__. That is, an object that returns something for __dataclass_fields__ even if it’s not a dataclass.

• bpo-37811: Fix socket module’s socket.connect(address) function being unable to establish connection in case of interrupted system call. The problem was observed on all OSes which poll(2) system call can take only non-negative integers and -1 as a timeout value.

• bpo-21131: Fix faulthandler.register(chain=True) stack. faulthandler now allocates a dedicated stack of SIGSTKSZ*2 bytes, instead of just SIGSTKSZ bytes. Calling the previous signal handler in faulthandler signal handler uses more than SIGSTKSZ bytes of stack memory on some platforms.

• bpo-34621: Fixed unpickle-ability in older Python versions (<3.7) of UUID objects with is_safe set to SafeUUID.unknown.

• bpo-37738: Fix the implementation of curses addch(str, color_pair): pass the color pair to setcchar(), instead of always passing 0 as the color pair.

• bpo-37723: Fix performance regression on regular expression parsing with huge character sets. Patch by Yann Vaginay.

• bpo-32178: Fix IndexError in email package when trying to parse invalid address fields starting with :.

• bpo-37685: Fixed comparisons of datetime.timedelta and datetime.timezone.

• bpo-37695: Correct curses.unget_wch() error message. Patch by Anthony Sottile.

• bpo-29553: Fixed argparse.ArgumentParser.format_usage() for mutually exclusive groups. Patch by Andrew Nester.

• bpo-37664: Update wheels bundled with ensurepip (pip 19.2.3 and setuptools 41.2.0)

• bpo-37642: Allowed the pure Python implementation of datetime.timezone to represent sub-minute offsets close to minimum and maximum boundaries, specifically in the ranges (23:59, 24:00) and (-23:59, 24:00). Patch by Ngalim Siregar

• bpo-37491: Fix IndexError when parsing email headers with unexpectedly ending bare-quoted string value. Patch by Abhilash Raj.

• bpo-18378: Recognize “UTF-8” as a valid value for LC_CTYPE in locale._parse_localename.

• bpo-37579: Return NotImplemented in Python implementation of __eq__ for timedelta and time when the other object being compared is not of the same type to match C implementation. Patch by Karthikeyan Singaravelan.

• bpo-21478: Record calls to parent when autospecced object is attached to a mock using unittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.

• bpo-37531: “python3 -m test -jN –timeout=TIMEOUT” now kills a worker process if it runs longer than TIMEOUT seconds.

• bpo-37482: Fix serialization of display name in originator or destination address fields with both encoded words and special chars.

• bpo-37424: Fixes a possible hang when using a timeout on subprocess.run() while capturing output. If the child process spawned its own children or otherwise connected its stdout or stderr handles with another process, we could hang after the timeout was reached and our child was killed when attempting to read final output from the pipes.

• bpo-37421: Fix multiprocessing.util.get_temp_dir() finalizer: clear also the ‘tempdir’ configuration of the current process, so next call to get_temp_dir() will create a new temporary directory, rather than reusing the removed temporary directory.

• bpo-37420: os.sched_setaffinity() now correctly handles errors that arise during iteration over its mask argument. Patch by Brandt Bucher.

• bpo-29412: Fix IndexError in parsing a header value ending unexpectedly. Patch by Abhilash Raj.

• bpo-37372: Fix error unpickling datetime.time objects from Python 2 with seconds>=24. Patch by Justin Blanchard.

• bpo-27860: Fix IPv4Interface and IPv6Interface didn’t accept string mask when the argument is tuple.

• bpo-33972: Email with single part but content-type set to multipart/* doesn’t raise AttributeError anymore.

• bpo-21872: Fix lzma: module decompresses data incompletely. When decompressing a FORMAT_ALONE format file, and it doesn’t have the end marker, sometimes the last one to dozens bytes can’t be output. Patch by Ma Lin.

• bpo-12144: Ensure cookies with expires attribute are handled in CookieJar.make_cookies().

• bpo-37163: dataclasses.replace() now supports the field named “obj”.

• bpo-36871: Ensure method signature is used instead of constructor signature of a class while asserting mock object against method calls. Patch by Karthikeyan Singaravelan.

• bpo-36564: Fix infinite loop in email header folding logic that would be triggered when an email policy’s max_line_length is not long enough to include the required markup and any values in the message. Patch by Paul Ganssle

• bpo-35168: shlex.shlex.punctuation_chars is now a read-only property.

• bpo-20504: Fixes a bug in cgi module when a multipart/form-data request has no Content-Length header.

• bpo-4963: Fixed non-deterministic behavior related to mimetypes extension mapping and module reinitialization.

Documentation

• bpo-26868: Fix example usage of PyModule_AddObject() to properly handle errors.

• bpo-37979: Added a link to dateutil.parser.isoparse in the datetime.fromisoformat documentation. Patch by Paul Ganssle

• bpo-37937: Mention frame.f_trace in sys.settrace() docs.

• bpo-37726: Stop recommending getopt in the tutorial for command line argument parsing and promote argparse.

• bpo-32910: Remove implementation-specific behaviour of how venv’s Deactivate works.

• bpo-37256: Fix wording of arguments for Request in urllib.request

• bpo-37284: Add a brief note to indicate that any new sys.implementation required attributes must go through the PEP process.

• bpo-30088: Documented that mailbox.Maildir constructor doesn’t attempt to verify the maildir folder layout correctness. Patch by Sviatoslav Sydorenko.

• bpo-37487: Fix PyList_GetItem index description to include 0.

• bpo-37478: Added possible exceptions to the description of os.chdir().

• bpo-37004: In the documentation for difflib, a note was added explicitly warning that the results of SequenceMatcher’s ratio method may depend on the order of the input strings.

• bpo-35803: Document and test that tempfile functions may accept a path-like object for the dir argument. Patch by Anthony Sottile.

• bpo-34293: Fix the Doc/Makefile regarding PAPER environment variable and PDF builds

Tests

• bpo-38239: Fix test_gdb for Link Time Optimization (LTO) builds.

• bpo-38275: test_ssl now handles disabled TLS/SSL versions better. OpenSSL’s crypto policy and run-time settings are recognized and tests for disabled versions are skipped. Tests also accept more TLS minimum_versions for platforms that override OpenSSL’s default with strict settings.

• bpo-38271: The private keys for test_ssl were encrypted with 3DES in traditional PKCS#5 format. 3DES and the digest algorithm of PKCS#5 are blocked by some strict crypto policies. Use PKCS#8 format with AES256 encryption instead.

• bpo-37123: Multiprocessing test test_mymanager() now also expects -SIGTERM, not only exitcode 0. BaseManager._finalize_manager() sends SIGTERM to the manager process if it takes longer than 1 second to stop, which happens on slow buildbots.

• bpo-38212: Multiprocessing tests: increase test_queue_feeder_donot_stop_onexc() timeout from 1 to 60 seconds.

• bpo-38117: Test with OpenSSL 1.1.1d

• bpo-37805: Add tests for json.dump(…, skipkeys=True). Patch by Dong-hee Na.

• bpo-37531: Enhance regrtest multiprocess timeout: write a message when killing a worker process, catch popen.kill() and popen.wait() exceptions, put a timeout on the second call to popen.communicate().

• bpo-37335: Improve locale coercion tests by using codec lookup instead of more fragile replace().

• bpo-37411: Fix test_wsgiref.testEnviron() to no longer depend on the environment variables (don’t fail if “X” variable is set).

• bpo-37400: Fix test_os.test_chown(): use os.getgroups() rather than grp.getgrall() to get groups. Rename also the test to test_chown_gid().

• bpo-37359: Add –cleanup option to python3 -m test to remove test_python_* directories of previous failed jobs. Add “make cleantest” to run python3 -m test --cleanup.

• bpo-37362: test_gdb no longer fails if it gets an “unexpected” message on stderr: it now ignores stderr. The purpose of test_gdb is to test that python-gdb.py commands work as expected, not to test gdb.

• bpo-36919: Make test_source_encoding.test_issue2301 implementation independent. The test will work now for both CPython and IronPython.

• bpo-34720: Assert m_state != NULL to mimic GC traversal functions that do not correctly handle module creation when the module state has not been created.

• bpo-34347: Fix test_utf8_mode.test_cmd_line for AIX. Patch by M. Felt

Build

• bpo-38301: In Solaris family, we must be sure to use -D_REENTRANT. Patch by Jesús Cea Avión.

• bpo-36002: Locate llvm-profdata and llvm-ar binaries using AC_PATH_TOOL rather than AC_PATH_TARGET_TOOL.

• bpo-37936: The .gitignore file no longer applies to any files that are in fact tracked in the Git repository. Patch by Greg Price.

Windows

• bpo-38117: Update bundled OpenSSL to 1.1.1d

• bpo-36634: venv activate.bat now works when the existing variables contain double quote characters.

• bpo-38087: Fix case sensitivity in test_pathlib and test_ntpath.

• bpo-38088: Fixes distutils not finding vcruntime140.dll with only the v142 toolset installed.

• bpo-37283: Ensure command-line and unattend.xml setting override previously detected states in Windows installer.

• bpo-37705: Improve the implementation of winerror_to_errno().

• bpo-37549: os.dup() no longer fails for standard streams on Windows 7.

• bpo-37702: Fix memory leak on Windows in creating an SSLContext object or running urllib.request.urlopen(’https://…’).

• bpo-10945: Officially drop support for creating bdist_wininst installers on non-Windows systems.

• bpo-37445: Include the FORMAT_MESSAGE_IGNORE_INSERTS flag in FormatMessageW() calls.

• bpo-37380: Don’t collect unfinished processes with subprocess._active on Windows to cleanup later. Patch by Ruslan Kuprieiev.

• bpo-32587: Make winreg.REG_MULTI_SZ support zero-length strings.

macOS

• bpo-38117: Updated OpenSSL to 1.1.1d in macOS installer.

• bpo-38089: Move Azure Pipelines to latest VM versions and make macOS tests optional

IDLE

• bpo-35379: When exiting IDLE, catch any AttributeError. One happens when EditorWindow.close is called twice. Printing a traceback, when IDLE is run from a terminal, is useless and annoying.

• bpo-38183: To avoid problems, test_idle ignores the user config directory. It no longer tries to create or access .idlerc or any files within. Users must run IDLE to discover problems with saving settings.

• bpo-38077: IDLE no longer adds ‘argv’ to the user namespace when initializing it. This bug only affected 3.7.4 and 3.8.0b2 to 3.8.0b4.

• bpo-38041: Shell restart lines now fill the window width, always start with ‘=’, and avoid wrapping unnecessarily. The line will still wrap if the included file name is long relative to the width.

• bpo-35771: To avoid occasional spurious test_idle failures on slower machines, increase the hover_delay in test_tooltip.

• bpo-37824: Properly handle user input warnings in IDLE shell. Cease turning SyntaxWarnings into SyntaxErrors.

• bpo-37929: IDLE Settings dialog now closes properly when there is no shell window.

• bpo-37902: Add mousewheel scrolling for IDLE module, path, and stack browsers. Patch by George Zhang.

• bpo-37849: Fixed completions list appearing too high or low when shown above the current line.

• bpo-36419: Refactor IDLE autocomplete and improve testing.

• bpo-37748: Reorder the Run menu. Put the most common choice, Run Module, at the top.

• bpo-37692: Improve highlight config sample with example shell interaction and better labels for shell elements.

• bpo-37628: Settings dialog no longer expands with font size.

• bpo-37627: Initialize the Customize Run dialog with the command line arguments most recently entered before. The user can optionally edit before submitting them.

• bpo-33610: Fix code context not showing the correct context when first toggled on.

• bpo-37530: Optimize code context to reduce unneeded background activity. Font and highlight changes now occur along with text changes instead of after a random delay.

• bpo-27452: Cleanup config.py by inlining RemoveFile and simplifying the handling of file in CreateConfigHandlers.

• bpo-37325: Fix tab focus traversal order for help source and custom run dialogs.

• bpo-17535: Add optional line numbers for IDLE editor windows. Windows open without line numbers unless set otherwise in the General tab of the configuration dialog.

• bpo-26806: To compensate for stack frames added by IDLE and avoid possible problems with low recursion limits, add 30 to limits in the user code execution process. Subtract 30 when reporting recursion limits to make this addition mostly transparent.

• bpo-36390: Gather Format menu functions into format.py. Combine paragraph.py, rstrip.py, and format methods from editor.py.

Tools/Demos

• bpo-37803: pdb’s --help and --version long options now work.

• bpo-37675: 2to3 now works when run from a zipped standard library.

Python 3.7.4 final

Release date: 2019-07-08

Core and Builtins

• bpo-37500: Due to unintended side effects, revert the change introduced by bpo-1875 in 3.7.4rc1 to check for syntax errors in dead conditional code blocks.

Documentation

• bpo-37149: Replace the dead link to the Tkinter 8.5 reference by John Shipman, New Mexico Tech, with a link to the archive.org copy.

Python 3.7.4 release candidate 2

Release date: 2019-07-02

Security

• bpo-37463: ssl.match_hostname() no longer accepts IPv4 addresses with additional text after the address and only quad-dotted notation without trailing whitespaces. Some inet_aton() implementations ignore whitespace and all data after whitespace, e.g. ‘127.0.0.1 whatever’.

Core and Builtins

• bpo-24214: Improved support of the surrogatepass error handler in the UTF-8 and UTF-16 incremental decoders.

Library

• bpo-37440: http.client now enables TLS 1.3 post-handshake authentication for default context or if a cert_file is passed to HTTPSConnection.

• bpo-37437: Update vendorized expat version to 2.2.7.

• bpo-37428: SSLContext.post_handshake_auth = True no longer sets SSL_VERIFY_POST_HANDSHAKE verify flag for client connections. Although the option is documented as ignored for clients, OpenSSL implicitly enables cert chain validation when the flag is set.

• bpo-32627: Fix compile error when _uuid headers conflicting included.

Windows

• bpo-37369: Fixes path for sys.executable when running from the Microsoft Store.

• bpo-35360: Update Windows builds to use SQLite 3.28.0.

macOS

• bpo-34602: Avoid test suite failures on macOS by no longer calling resource.setrlimit to increase the process stack size limit at runtime. The runtime change is no longer needed since the interpreter is being built with a larger default stack size.

Python 3.7.4 release candidate 1

Release date: 2019-06-18

Security

• bpo-35907: CVE-2019-9948: Avoid file reading by disallowing local-file:// and local_file:// URL schemes in URLopener().open() and URLopener().retrieve() of urllib.request.

• bpo-36742: Fixes mishandling of pre-normalization characters in urlsplit().

• bpo-30458: Address CVE-2019-9740 by disallowing URL paths with embedded whitespace or control characters through into the underlying http client request. Such potentially malicious header injection URLs now cause an http.client.InvalidURL exception to be raised.

• bpo-33529: Prevent fold function used in email header encoding from entering infinite loop when there are too many non-ASCII characters in a header.

• bpo-35755: shutil.which() now uses os.confstr("CS_PATH") if available and if the PATH environment variable is not set. Remove also the current directory from posixpath.defpath. On Unix, shutil.which() and the subprocess module no longer search the executable in the current directory if the PATH environment variable is not set.

Core and Builtins

• bpo-37269: Fix a bug in the peephole optimizer that was not treating correctly constant conditions with binary operators. Patch by Pablo Galindo.

• bpo-37219: Remove errorneous optimization for empty set differences.

• bpo-26423: Fix possible overflow in wrap_lenfunc() when sizeof(long) < sizeof(Py_ssize_t) (e.g., 64-bit Windows).

• bpo-36829: PyErr_WriteUnraisable() now displays the exception even if displaying the traceback failed. Moreover, hold a strong reference to sys.stderr while using it. Document that an exception must be set when calling PyErr_WriteUnraisable().

• bpo-36907: Fix a crash when calling a C function with a keyword dict (f(**kwargs)) and changing the dict kwargs while that function is running.

• bpo-36946: Fix possible signed integer overflow when handling slices.

• bpo-27987: PyGC_Head structure is aligned to long double. This is needed to ensure GC-ed objects are aligned properly. Patch by Inada Naoki.

• bpo-1875: A SyntaxError is now raised if a code blocks that will be optimized away (e.g. if conditions that are always false) contains syntax errors. Patch by Pablo Galindo. (Reverted in 3.7.4 final by bpo-37500.)

• bpo-28866: Avoid caching attributes of classes which type defines mro() to avoid a hard cache invalidation problem.

• bpo-27639: Correct return type for UserList slicing operations. Patch by Michael Blahay, Erick Cervantes, and vaultah

• bpo-32849: Fix Python Initialization code on FreeBSD to detect properly when stdin file descriptor (fd 0) is invalid.

• bpo-27987: pymalloc returns memory blocks aligned by 16 bytes, instead of 8 bytes, on 64-bit platforms to conform x86-64 ABI. Recent compilers assume this alignment more often. Patch by Inada Naoki.

• bpo-36504: Fix signed integer overflow in _ctypes.c’s PyCArrayType_new().

• bpo-20844: Fix running script with encoding cookie and LF line ending may fail on Windows.

• bpo-24214: Fixed support of the surrogatepass error handler in the UTF-8 incremental decoder.

• bpo-36459: Fix a possible double PyMem_FREE() due to tokenizer.c’s tok_nextc().

• bpo-36433: Fixed TypeError message in classmethoddescr_call.

• bpo-36430: Fix a possible reference leak in itertools.count().

• bpo-36440: Include node names in ParserError messages, instead of numeric IDs. Patch by A. Skrobov.

• bpo-36421: Fix a possible double decref in _ctypes.c’s PyCArrayType_new().

• bpo-36256: Fix bug in parsermodule when parsing a state in a DFA that has two or more arcs with labels of the same type. Patch by Pablo Galindo.

• bpo-36236: At Python initialization, the current directory is no longer prepended to sys.path if it has been removed.

• bpo-36262: Fix an unlikely memory leak on conversion from string to float in the function _Py_dg_strtod() used by float(str), complex(str), pickle.load(), marshal.load(), etc.

• bpo-36218: Fix a segfault occuring when sorting a list of heterogeneous values. Patch contributed by Rémi Lapeyre and Elliot Gorokhovsky.

• bpo-36035: Added fix for broken symlinks in combination with pathlib

• bpo-18372: Add missing PyObject_GC_Track() calls in the pickle module. Patch by Zackery Spytz.

• bpo-34408: Prevent a null pointer dereference and resource leakage in PyInterpreterState_New().

Library

• bpo-37280: Use threadpool for reading from file for sendfile fallback mode.

• bpo-37279: Fix asyncio sendfile support when sendfile sends extra data in fallback mode.

• bpo-19865: ctypes.create_unicode_buffer() now also supports non-BMP characters on platforms with 16-bit wchar_t (for example, Windows and AIX).

• bpo-35922: Fix RobotFileParser.crawl_delay() and RobotFileParser.request_rate() to return None rather than raise AttributeError when no relevant rule is defined in the robots.txt file. Patch by Rémi Lapeyre.

• bpo-36607: Eliminate RuntimeError raised by asyncio.all_tasks() if internal tasks weak set is changed by another thread during iteration.

• bpo-36402: Fix a race condition at Python shutdown when waiting for threads. Wait until the Python thread state of all non-daemon threads get deleted (join all non-daemon threads), rather than just wait until non-daemon Python threads complete.

• bpo-34886: Fix an unintended ValueError from subprocess.run() when checking for conflicting input and stdin or capture_output and stdout or stderr args when they were explicitly provided but with None values within a passed in **kwargs dict rather than as passed directly by name. Patch contributed by Rémi Lapeyre.

• bpo-37173: The exception message for inspect.getfile() now correctly reports the passed class rather than the builtins module.

• bpo-12639: msilib.Directory.start_component() no longer fails if keyfile is not None.

• bpo-36520: Lengthy email headers with UTF-8 characters are now properly encoded when they are folded. Patch by Jeffrey Kintscher.

• bpo-37054: Fix destructor _pyio.BytesIO and _pyio.TextIOWrapper: initialize their _buffer attribute as soon as possible (in the class body), because it’s used by __del__() which calls close().

• bpo-30835: Fixed a bug in email parsing where a message with invalid bytes in content-transfer-encoding of a multipart message can cause an AttributeError. Patch by Andrew Donnellan.

• bpo-37035: Don’t log OSError based exceptions if a fatal error has occurred in asyncio transport. Peer can generate almost any OSError, user cannot avoid these exceptions by fixing own code. Errors are still propagated to user code, it’s just logging them is pointless and pollute asyncio logs.

• bpo-37008: Add support for calling next() with the mock resulting from unittest.mock.mock_open()

• bpo-27737: Allow whitespace only header encoding in email.header - by Batuhan Taskaya

• bpo-36969: PDB command args now display keyword only arguments. Patch contributed by Rémi Lapeyre.

• bpo-36983: Add missing names to typing.__all__: ChainMap, ForwardRef, OrderedDict - by Anthony Sottile.

• bpo-21315: Email headers containing RFC2047 encoded words are parsed despite the missing whitespace, and a defect registered. Also missing trailing whitespace after encoded words is now registered as a defect.

• bpo-33524: Fix the folding of email header when the max_line_length is 0 or None and the header contains non-ascii characters. Contributed by Licht Takeuchi (@Licht-T).

• bpo-24564: shutil.copystat() now ignores errno.EINVAL on os.setxattr() which may occur when copying files on filesystems without extended attributes support.

  Original patch by Giampaolo Rodola, updated by Ying Wang.

• bpo-36845: Added validation of integer prefixes to the construction of IP networks and interfaces in the ipaddress module.

• bpo-35545: Fix asyncio discarding IPv6 scopes when ensuring hostname resolutions internally

• bpo-35070: posix.getgrouplist() now works correctly when the user belongs to NGROUPS_MAX supplemental groups. Patch by Jeffrey Kintscher.

• bpo-24538: In shutil.copystat(), first copy extended file attributes and then file permissions, since extended attributes can only be set on the destination while it is still writeable.

• bpo-33110: Handle exceptions raised by functions added by concurrent.futures add_done_callback correctly when the Future has already completed.

• bpo-26903: Limit max_workers in ProcessPoolExecutor to 61 to work around a WaitForMultipleObjects limitation.

• bpo-36813: Fix QueueListener to call queue.task_done() upon stopping. Patch by Bar Harel.

• bpo-36734: Fix compilation of faulthandler.c on HP-UX. Initialize stack_t current_stack to zero using memset().

• bpo-29183: Fix double exceptions in wsgiref.handlers.BaseHandler by calling its close() method only when no exception is raised.

• bpo-36650: The C version of functools.lru_cache() was treating calls with an empty **kwargs dictionary as being distinct from calls with no keywords at all. This did not result in an incorrect answer, but it did trigger an unexpected cache miss.

• bpo-28552: Fix distutils.sysconfig if sys.executable is None or an empty string: use os.getcwd() to initialize project_base. Fix also the distutils build command: don’t use sys.executable if it is None or an empty string.

• bpo-35755: shutil.which() and distutils.spawn.find_executable() now use os.confstr("CS_PATH") if available instead of os.defpath, if the PATH environment variable is not set. Moreover, don’t use os.confstr("CS_PATH") nor os.defpath if the PATH environment variable is set to an empty string.

• bpo-36613: Fix asyncio wait() not removing callback if exception

• bpo-36598: Fix isinstance check for Mock objects with spec when the code is executed under tracing. Patch by Karthikeyan Singaravelan.

• bpo-36533: Reinitialize logging.Handler locks in forked child processes instead of attempting to acquire them all in the parent before forking only to be released in the child process. The acquire/release pattern was leading to deadlocks in code that has implemented any form of chained logging handlers that depend upon one another as the lock acquision order cannot be guaranteed.

• bpo-36522: If debuglevel is set to >0 in http.client, print all values for headers with multiple values for the same header name. Patch by Matt Houglum.

• bpo-36492: Arbitrary keyword arguments (even with names “self” and “func”) can now be passed to some functions which should accept arbitrary keyword arguments and pass them to other function (for example partialmethod(), TestCase.addCleanup() and Profile.runcall()) if the required arguments are passed as positional arguments.

• bpo-36434: Errors during writing to a ZIP file no longer prevent to properly close it.

• bpo-34745: Fix asyncio ssl memory issues caused by circular references

• bpo-36321: collections.namedtuple() misspelled the name of an attribute. To be consistent with typing.NamedTuple, the attribute name should have been “_field_defaults” instead of “_fields_defaults”. For backwards compatibility, both spellings are now created. The misspelled version may be removed in the future.

• bpo-36272: logging does not silently ignore RecursionError anymore. Patch contributed by Rémi Lapeyre.

• bpo-36235: Fix CFLAGS in customize_compiler() of distutils.sysconfig: when the CFLAGS environment variable is defined, don’t override CFLAGS variable with the OPT variable anymore. Initial patch written by David Malcolm.

• bpo-35125: Asyncio: Remove inner callback on outer cancellation in shield

• bpo-35802: Clean up code which checked presence of os.stat / os.lstat / os.chmod which are always present. Patch by Anthony Sottile.

• bpo-23078: Add support for classmethod() and staticmethod() to unittest.mock.create_autospec(). Initial patch by Felipe Ochoa.

• bpo-35721: Fix asyncio.SelectorEventLoop.subprocess_exec() leaks file descriptors if Popen fails and called with stdin=subprocess.PIPE. Patch by Niklas Fiekas.

• bpo-35726: QueueHandler.prepare() now makes a copy of the record before modifying and enqueueing it, to avoid affecting other handlers in the chain.

• bpo-31855: unittest.mock.mock_open() results now respects the argument of read([size]). Patch contributed by Rémi Lapeyre.

• bpo-35082: Don’t return deleted attributes when calling dir on a unittest.mock.Mock.

• bpo-34547: wsgiref.handlers.BaseHandler now handles abrupt client connection terminations gracefully. Patch by Petter Strandmark.

• bpo-34424: Fix serialization of messages containing encoded strings when the policy.linesep is set to a multi-character string. Patch by Jens Troeger.

• bpo-33361: Fix a bug in codecs.StreamRecoder where seeking might leave old data in a buffer and break subsequent read calls. Patch by Ammar Askar.

• bpo-31922: asyncio.AbstractEventLoop.create_datagram_endpoint(): Do not connect UDP socket when broadcast is allowed. This allows to receive replies after a UDP broadcast.

• bpo-22102: Added support for ZIP files with disks set to 0. Such files are commonly created by builtin tools on Windows when use ZIP64 extension. Patch by Francisco Facioni.

• bpo-27141: Added a __copy__() to collections.UserList and collections.UserDict in order to correctly implement shallow copying of the objects. Patch by Bar Harel.

• bpo-31829: \r, \0 and \x1a (end-of-file on Windows) are now escaped in protocol 0 pickles of Unicode strings. This allows to load them without loss from files open in text mode in Python 2.

• bpo-31292: Fix setup.py check --restructuredtext for files containing include directives.

• bpo-23395: _thread.interrupt_main() now avoids setting the Python error status if the SIGINT signal is ignored or not handled by Python.

Documentation

• bpo-34903: Documented that in datetime.datetime.strptime(), the leading zero in some two-digit formats is optional. Patch by Mike Gleen.

• bpo-36984: Improve version added references in typing module - by Anthony Sottile.

• bpo-36868: What’s new now mentions SSLContext.hostname_checks_common_name instead of SSLContext.host_flags.

• bpo-36783: Added C API Documentation for Time_FromTimeAndFold and PyDateTime_FromDateAndTimeAndFold as per PEP 495. Patch by Edison Abahurire.

• bpo-30840: Document relative imports

• bpo-36523: Add docstring for io.IOBase.writelines().

• bpo-36425: New documentation translation: Simplified Chinese.

• bpo-36157: Added Documention for PyInterpreterState_Main().

• bpo-36138: Improve documentation about converting datetime.timedelta to scalars.

• bpo-22865: Add detail to the documentation on the pty.spawn function.

• bpo-35581: @typing.type_check_only now allows type stubs to mark functions and classes not available during runtime.

• bpo-35564: Explicitly set master_doc variable in conf.py for compliance with Sphinx 2.0

• bpo-10536: Enhance the gettext docs. Patch by Éric Araujo

• bpo-32995: Added the context variable in glossary.

• bpo-33832: Add glossary entry for ‘magic method’.

• bpo-33482: Make codecs.StreamRecoder.writelines take a list of bytes.

• bpo-25735: Added documentation for func factorial to indicate that returns integer values

Tests

• bpo-35998: Avoid TimeoutError in test_asyncio: test_start_tls_server_1()

• bpo-37153: test_venv.test_mutiprocessing() now explicitly calls pool.terminate() to wait until the pool completes.

• bpo-37081: Test with OpenSSL 1.1.1c

• bpo-36915: The main regrtest process now always removes all temporary directories of worker processes even if they crash or if they are killed on KeyboardInterrupt (CTRL+c).

• bpo-36719: “python3 -m test -jN …” now continues the execution of next tests when a worker process crash (CHILD_ERROR state). Previously, the test suite stopped immediately. Use –failfast to stop at the first error.

• bpo-36816: Update Lib/test/selfsigned_pythontestdotnet.pem to match self-signed.pythontest.net’s new TLS certificate.

• bpo-35925: Skip httplib and nntplib networking tests when they would otherwise fail due to a modern OS or distro with a default OpenSSL policy of rejecting connections to servers with weak certificates.

• bpo-36719: regrtest now always detects uncollectable objects. Previously, the check was only enabled by --findleaks. The check now also works with -jN/--multiprocess N. --findleaks becomes a deprecated alias to --fail-env-changed.

• bpo-36725: When using mulitprocessing mode (-jN), regrtest now better reports errors if a worker process fails, and it exits immediately on a worker thread failure or when interrupted.

• bpo-36454: Change test_time.test_monotonic() to test only the lower bound of elapsed time after a sleep command rather than the upper bound. This prevents unnecessary test failures on slow buildbots. Patch by Victor Stinner.

• bpo-36629: Fix test_imap4_host_default_value() of test_imaplib: catch also errno.ENETUNREACH error.

• bpo-36611: Fix test_sys.test_getallocatedblocks() when tracemalloc is enabled.

• bpo-36560: Fix reference leak hunting in regrtest: compute also deltas (of reference count, allocated memory blocks, file descriptor count) during warmup, to ensure that everything is initialized before starting to hunt reference leaks.

• bpo-36565: Fix reference hunting (python3 -m test -R 3:3) when Python has no built-in abc module.

• bpo-36436: Fix _testcapi.pymem_buffer_overflow(): handle memory allocation failure.

Build

• bpo-36605: make tags and make TAGS now also parse Modules/_io/*.c and Modules/_io/*.h.

• bpo-36508: python-config --ldflags no longer includes flags of the LINKFORSHARED variable. The LINKFORSHARED variable must only be used to build executables.

Windows

• bpo-34631: Updated OpenSSL to 1.1.1c in Windows installer

• bpo-37267: On Windows, os.dup() no longer creates an inheritable fd when handling a character file.

• bpo-36779: Ensure time.tzname is correct on Windows when the active code page is set to CP_UTF7 or CP_UTF8.

• bpo-36965: include of STATUS_CONTROL_C_EXIT without depending on MSC compiler

• bpo-36649: Remove trailing spaces for registry keys when installed via the Store.

• bpo-34144: Fixed activate.bat to correctly update codepage when chcp.com returns dots in output. Patch by Lorenz Mende.

• bpo-35941: enum_certificates function of the ssl module now returns certificates from all available certificate stores inside windows in a query instead of returning only certificates from the system wide certificate store. This includes certificates from these certificate stores: local machine, local machine enterprise, local machine group policy, current user, current user group policy, services, users. ssl.enum_crls() function is changed in the same way to return all certificate revocation lists inside the windows certificate revocation list stores.

• bpo-36441: Fixes creating a venv when debug binaries are installed.

• bpo-36312: Fixed decoders for the following code pages: 50220, 50221, 50222, 50225, 50227, 50229, 57002 through 57011, 65000 and 42.

• bpo-36010: Add the venv standard library module to the nuget distribution for Windows.

• bpo-34060: Report system load when running test suite on Windows. Patch by Ammar Askar. Based on prior work by Jeremy Kloth.

macOS

• bpo-35360: Update macOS installer to use SQLite 3.28.0.

• bpo-34631: Updated OpenSSL to 1.1.1c in macOS installer.

• bpo-36231: Support building Python on macOS without /usr/include installed. As of macOS 10.14, system header files are only available within an SDK provided by either the Command Line Tools or the Xcode app.

• bpo-34602: Avoid failures setting macOS stack resource limit with resource.setrlimit. This reverts an earlier fix for bpo-18075 which forced a non-default stack size when building the interpreter executable on macOS.

IDLE

• bpo-37321: Both subprocess connection error messages now refer to the ‘Startup failure’ section of the IDLE doc.

• bpo-37177: Properly ‘attach’ search dialogs to their main window so that they behave like other dialogs and do not get hidden behind their main window.

• bpo-37039: Adjust “Zoom Height” to individual screens by momemtarily maximizing the window on first use with a particular screen. Changing screen settings may invalidate the saved height. While a window is maximized, “Zoom Height” has no effect.

• bpo-35763: Make calltip reminder about ‘/’ meaning positional-only less obtrusive by only adding it when there is room on the first line.

• bpo-5680: Add ‘Run… Customized’ to the Run menu to run a module with customized settings. Any ‘command line arguments’ entered are added to sys.argv. One can suppress the normal Shell main module restart.

• bpo-35610: Replace now redundant .context_use_ps1 with .prompt_last_line. This finishes change started in bpo-31858.

• bpo-37038: Make idlelib.run runnable; add test clause.

• bpo-36958: Print any argument other than None or int passed to SystemExit or sys.exit().

• bpo-13102: When saving a file, call os.fsync() so bits are flushed to e.g. USB drive.

• bpo-36429: Fix starting IDLE with pyshell. Add idlelib.pyshell alias at top; remove pyshell alias at bottom. Remove obsolete __name__==’__main__’ command.

• bpo-36405: Use dict unpacking in idlelib.

• bpo-36396: Remove fgBg param of idlelib.config.GetHighlight(). This param was only used twice and changed the return type.

• bpo-23205: For the grep module, add tests for findfiles, refactor findfiles to be a module-level function, and refactor findfiles to use os.walk.

• bpo-23216: Add docstrings to IDLE search modules.

• bpo-30348: Increase test coverage of idlelib.autocomplete by 30%.

• bpo-32411: In browser.py, remove extraneous sorting by line number since dictionary was created in line number order.

Tools/Demos

• bpo-14546: Fix the argument handling in Tools/scripts/lll.py.

• bpo-32217: Fix freeze script on Windows.

C API

• bpo-28805: The METH_FASTCALL calling convention has been documented.

• bpo-37170: Fix the cast on error in PyLong_AsUnsignedLongLongMask().

• bpo-36389: Change the value of CLEANBYTE, DEADDYTE and FORBIDDENBYTE internal constants used by debug hooks on Python memory allocators (PyMem_SetupDebugHooks() function). Byte patterns 0xCB, 0xDB and 0xFB have been replaced with 0xCD, 0xDD and 0xFD to use the same values than Windows CRT debug malloc() and free().

Python 3.7.3 final

Release date: 2019-03-25

There were no new changes in version 3.7.3.

Python 3.7.3 release candidate 1

Release date: 2019-03-12

Security

• bpo-36216: Changes urlsplit() to raise ValueError when the URL contains characters that decompose under IDNA encoding (NFKC-normalization) into characters that affect how the URL is parsed.

• bpo-35746: [CVE-2019-5010] Fix a NULL pointer deref in ssl module. The cert parser did not handle CRL distribution points with empty DP or URI correctly. A malicious or buggy certificate can result into segfault. Vulnerability (TALOS-2018-0758) reported by Colin Read and Nicolas Edet of Cisco.

• bpo-35121: Don’t send cookies of domain A without Domain attribute to domain B when domain A is a suffix match of domain B while using a cookiejar with http.cookiejar.DefaultCookiePolicy policy. Patch by Karthikeyan Singaravelan.

Core and Builtins

• bpo-35942: The error message emitted when returning invalid types from __fspath__ in interfaces that allow passing PathLike objects has been improved and now it does explain the origin of the error.

• bpo-35992: Fix __class_getitem__() not being called on a class with a custom non-subscriptable metaclass.

• bpo-35991: Fix a potential double free in Modules/_randommodule.c.

• bpo-35961: Fix a crash in slice_richcompare(): use strong references rather than stolen references for the two temporary internal tuples.

• bpo-31506: Clarify the errors reported when object.__new__ and object.__init__ receive more than one argument. Contributed by Sanyam Khurana.

• bpo-35720: Fixed a minor memory leak in pymain_parse_cmdline_impl function in Modules/main.c

• bpo-35623: Fix a crash when sorting very long lists. Patch by Stephan Hohe.

• bpo-35214: clang Memory Sanitizer build instrumentation was added to work around false positives from posix, socket, time, test_io, and test_faulthandler.

• bpo-35560: Fix an assertion error in format() in debug build for floating point formatting with “n” format, zero padding and small width. Release build is not impacted. Patch by Karthikeyan Singaravelan.

• bpo-35552: Format characters %s and %V in PyUnicode_FromFormat() and %s in PyBytes_FromFormat() no longer read memory past the limit if precision is specified.

• bpo-35504: Fix segfaults and SystemErrors when deleting certain attributes. Patch by Zackery Spytz.

• bpo-33989: Fix a possible crash in list.sort() when sorting objects with ob_type->tp_richcompare == NULL. Patch by Zackery Spytz.

Library

• bpo-35931: The pdb debug command now gracefully handles all exceptions.

• bpo-36251: Fix format strings used for stderrprinter and re.Match reprs. Patch by Stephan Hohe.

• bpo-35807: Update ensurepip to install pip 19.0.3 and setuptools 40.8.0.

• bpo-36179: Fix two unlikely reference leaks in _hashopenssl. The leaks only occur in out-of-memory cases.

• bpo-35178: Ensure custom warnings.formatwarning() function can receive line as positional argument. Based on patch by Tashrif Billah.

• bpo-36106: Resolve potential name clash with libm’s sinpi(). Patch by Dmitrii Pasechnik.

• bpo-35512: unittest.mock.patch.dict() used as a decorator with string target resolves the target during function call instead of during decorator construction. Patch by Karthikeyan Singaravelan.

• bpo-36091: Clean up reference to async generator in Lib/types. Patch by Henry Chen.

• bpo-35899: Enum has been fixed to correctly handle empty strings and strings with non-Latin characters (ie. ‘α’, ‘א’) without crashing. Original patch contributed by Maxwell. Assisted by Stéphane Wirtel.

• bpo-35918: Removed broken has_key method from multiprocessing.managers.SyncManager.dict. Contributed by Rémi Lapeyre.

• bpo-35960: Fix dataclasses.field() throwing away empty mapping objects passed as metadata.

• bpo-35847: RISC-V needed the CTYPES_PASS_BY_REF_HACK. Fixes ctypes Structure test_pass_by_value.

• bpo-35780: Fix lru_cache() errors arising in recursive, reentrant, or multi-threaded code. These errors could result in orphan links and in the cache being trapped in a state with fewer than the specified maximum number of links. Fix handling of negative maxsize which should have been treated as zero. Fix errors in toggling the “full” status flag. Fix misordering of links when errors are encountered. Sync-up the C code and pure Python code for the space saving path in functions with a single positional argument. In this common case, the space overhead of an lru cache entry is reduced by almost half. Fix counting of cache misses. In error cases, the miss count was out of sync with the actual number of times the underlying user function was called.

• bpo-23846: asyncio.ProactorEventLoop now catches and logs send errors when the self-pipe is full.

• bpo-34323: asyncio: Enhance IocpProactor.close() log: wait 1 second before the first log, then log every second. Log also the number of seconds since close() was called.

• bpo-34294: re module, fix wrong capturing groups in rare cases. re.search(), re.findall(), re.sub() and other functions that scan through string looking for a match, should reset capturing groups between two match attempts. Patch by Ma Lin.

• bpo-35717: Fix KeyError exception raised when using enums and compile. Patch contributed by Rémi Lapeyre.

• bpo-35699: Fixed detection of Visual Studio Build Tools 2017 in distutils

• bpo-32710: Fix memory leaks in asyncio ProactorEventLoop on overlapped operation failure.

• bpo-32710: Fix a memory leak in asyncio in the ProactorEventLoop when ReadFile() or WSASend() overlapped operation fail immediately: release the internal buffer.

• bpo-35682: Fix asyncio.ProactorEventLoop.sendfile(): don’t attempt to set the result of an internal future if it’s already done.

• bpo-35283: Add a pending deprecated warning for the threading.Thread.isAlive() method. Patch by Dong-hee Na.

• bpo-35643: Fixed a SyntaxWarning: invalid escape sequence in Modules/_sha3/cleanup.py. Patch by Mickaël Schoentgen.

• bpo-35615: weakref: Fix a RuntimeError when copying a WeakKeyDictionary or a WeakValueDictionary, due to some keys or values disappearing while iterating.

• bpo-28503: The crypt module now internally uses the crypt_r() library function instead of crypt() when available.

• bpo-35121: Don’t set cookie for a request when the request path is a prefix match of the cookie’s path attribute but doesn’t end with “/”. Patch by Karthikeyan Singaravelan.

• bpo-35585: Speed-up building enums by value, e.g. http.HTTPStatus(200).

• bpo-21478: Calls to a child function created with unittest.mock.create_autospec() should propagate to the parent. Patch by Karthikeyan Singaravelan.

• bpo-35513: TextTestRunner of unittest.runner now uses time.perf_counter() rather than time.time() to measure the execution time of a test: time.time() can go backwards, whereas time.perf_counter() is monotonic.

• bpo-35502: Fixed reference leaks in xml.etree.ElementTree.TreeBuilder in case of unfinished building of the tree (in particular when an error was raised during parsing XML).

• bpo-31446: Copy command line that was passed to CreateProcessW since this function can change the content of the input buffer.

• bpo-20239: Allow repeated assignment deletion of unittest.mock.Mock attributes. Patch by Pablo Galindo.

• bpo-17185: Set __signature__ on mock for inspect to get signature. Patch by Karthikeyan Singaravelan.

• bpo-10496: check_environ() of distutils.utils now catches KeyError on calling pwd.getpwuid(): don’t create the HOME environment variable in this case.

• bpo-35066: Previously, calling the strftime() method on a datetime object with a trailing ‘%’ in the format string would result in an exception. However, this only occured when the datetime C module was being used; the python implementation did not match this behavior. Datetime is now PEP-399 compliant, and will not throw an exception on a trailing ‘%’.

• bpo-24746: Avoid stripping trailing whitespace in doctest fancy diff. Orignial patch by R. David Murray & Jairo Trad. Enhanced by Sanyam Khurana.

• bpo-35198: Fix C++ extension compilation on AIX

• bpo-28441: On Cygwin and MinGW, ensure that sys.executable always includes the full filename in the path, including the .exe suffix (unless it is a symbolic link).

• bpo-34572: Fix C implementation of pickle.loads to use importlib’s locking mechanisms, and thereby avoid using partially-loaded modules. Patch by Tim Burgess.

• bpo-33687: Fix the call to os.chmod() for uu.decode() if a mode is given or decoded. Patch by Timo Furrer.

• bpo-32146: Document the interaction between frozen executables and the spawn and forkserver start methods in multiprocessing.

Documentation

• bpo-36083: Fix formatting of –check-hash-based-pycs options in the manpage Synopsis.

• bpo-34764: Improve example of iter() with 2nd sentinel argument.

• bpo-21314: A new entry was added to the Core Language Section of the Programming FAQ, which explaines the usage of slash(/) in the signature of a function. Patch by Lysandros Nikolaou

• bpo-22062: Update documentation and docstrings for pathlib. Original patch by Mike Short.

Tests

• bpo-36234: test_posix.PosixUidGidTests: add tests for invalid uid/gid type (str). Initial patch written by David Malcolm.

• bpo-29571: Fix test_re.test_locale_flag(): use locale.getpreferredencoding() rather than locale.getlocale() to get the locale encoding. With some locales, locale.getlocale() returns the wrong encoding. On Windows, set temporarily the LC_CTYPE locale to the user preferred encoding to ensure that it uses the ANSI code page, to be consistent with locale.getpreferredencoding().

• bpo-36123: Fix race condition in test_socket.

• bpo-27313: Avoid test_ttk_guionly ComboboxTest failure with macOS Cocoa Tk.

• bpo-36019: Add test.support.TEST_HTTP_URL and replace references of http://www.example.com by this new constant. Contributed by Stéphane Wirtel.

• bpo-36037: Fix test_ssl for strict OpenSSL configuration like RHEL8 strict crypto policy. Use older TLS version for minimum TLS version of the server SSL context if needed, to test TLS version older than default minimum TLS version.

• bpo-35505: Make test_imap4_host_default_value independent on whether the local IMAP server is running.

• bpo-35917: multiprocessing: provide unit tests for SyncManager and SharedMemoryManager classes + all the shareable types which are supposed to be supported by them. (patch by Giampaolo Rodola)

• bpo-35772: Fix sparse file tests of test_tarfile on ppc64 with the tmpfs filesystem. Fix the function testing if the filesystem supports sparse files: create a file which contains data and “holes”, instead of creating a file which contains no data. tmpfs effective block size is a page size (tmpfs lives in the page cache). RHEL uses 64 KiB pages on aarch64, ppc64, ppc64le, only s390x and x86_64 use 4 KiB pages, whereas the test punch holes of 4 KiB.

• bpo-35045: Make ssl tests less strict and also accept TLSv1 as system default. The changes unbreaks test_min_max_version on Fedora 29.

• bpo-31731: Fix a race condition in check_interrupted_write() of test_io: create directly the thread with SIGALRM signal blocked, rather than blocking the signal later from the thread. Previously, it was possible that the thread gets the signal before the signal is blocked.

• bpo-35424: Fix test_multiprocessing_main_handling: use multiprocessing.Pool with a context manager and then explicitly join the pool.

• bpo-35519: Rename test.bisect module to test.bisect_cmd to avoid conflict with bisect module when running directly a test like ./python Lib/test/test_xmlrpc.py.

• bpo-35513: Replace time.time() with time.monotonic() in tests to measure time delta.

• bpo-34279: test.support.run_unittest() no longer raise TestDidNotRun if the test result contains skipped tests. The exception is now only raised if no test have been run and no test have been skipped.

• bpo-35412: Add testcase to test_future4: check unicode literal.

• bpo-26704: Added test demonstrating double-patching of an instance method. Patch by Anthony Sottile.

Build

• bpo-34691: The _contextvars module is now built into the core Python library on Windows.

• bpo-35683: Improved Azure Pipelines build steps and now verifying layouts correctly

• bpo-35642: Remove asynciomodule.c from pythoncore.vcxproj

• bpo-35550: Fix incorrect Solaris #ifdef checks to look for __sun && __SVR4 instead of sun when compiling.

Windows

• bpo-24643: Fix name collisions due to #define timezone _timezone in PC/pyconfig.h.

• bpo-35692: pathlib no longer raises when checking file and directory existence on drives that are not ready

• bpo-35872: Uses the base Python executable when invoking venv in a virtual environment

• bpo-35873: Prevents venv paths being inherited by child processes

• bpo-35299: Fix sysconfig detection of the source directory and distutils handling of pyconfig.h during PGO profiling

• bpo-32560: The py launcher now forwards its STARTUPINFO structure to child processes.

• bpo-35854: Fix EnvBuilder and –symlinks in venv on Windows

• bpo-35811: Avoid propagating venv settings when launching via py.exe

• bpo-35797: Fix default executable used by the multiprocessing module

• bpo-29734: Fix handle leaks in os.stat on Windows.

• bpo-35596: Use unchecked PYCs for the embeddable distro to avoid zipimport restrictions.

• bpo-35596: Fix vcruntime140.dll being added to embeddable distro multiple times.

• bpo-35402: Update Windows build to use Tcl and Tk 8.6.9

• bpo-33316: PyThread_release_lock always fails

• bpo-1104: Correctly handle string length in msilib.SummaryInfo.GetProperty() to prevent it from truncating the last character.

IDLE

• bpo-36176: Fix IDLE autocomplete & calltip popup colors. Prevent conflicts with Linux dark themes (and slightly darken calltip background).

• bpo-36152: Remove colorizer.ColorDelegator.close_when_done and the corresponding argument of .close(). In IDLE, both have always been None or False since 2007.

• bpo-32129: Avoid blurry IDLE application icon on macOS with Tk 8.6. Patch by Kevin Walzer.

• bpo-24310: IDLE – Document settings dialog font tab sample.

• bpo-36096: Refactor class variables to instance variables in colorizer.

• bpo-35833: Revise IDLE doc for control codes sent to Shell. Add a code example block.

• bpo-35770: IDLE macosx deletes Options => Configure IDLE. It previously deleted Window => Zoom Height by mistake. (Zoom Height is now on the Options menu). On Mac, the settings dialog is accessed via Preferences on the IDLE menu.

• bpo-35769: Change IDLE’s new file name from ‘Untitled’ to ‘untitled’

• bpo-35689: Add docstrings and unittests for colorizer.py.

• bpo-35660: Fix imports in idlelib.window.

• bpo-35641: Proper format calltip when the function has no docstring.

• bpo-33987: Use ttk Frame for ttk widgets.

• bpo-34055: Fix erroneous ‘smart’ indents and newlines in IDLE Shell.

• bpo-35591: Find Selection now works when selection not found.

• bpo-35196: Speed up squeezer line counting.

• bpo-35598: Update config_key: use PEP 8 names and ttk widgets, make some objects global, and add tests.

• bpo-28097: Add Previous/Next History entries to Shell menu.

• bpo-35208: Squeezer now properly counts wrapped lines before newlines.

• bpo-35555: Gray out Code Context menu entry when it’s not applicable.

• bpo-35521: Document the IDLE editor code context feature. Add some internal references within the IDLE doc.

• bpo-22703: The Code Context menu label now toggles between Show/Hide Code Context. The Zoom Height menu now toggles between Zoom/Restore Height. Zoom Height has moved from the Window menu to the Options menu.

Tools/Demos

• bpo-35132: Fix py-list and py-bt commands of python-gdb.py on gdb7.

C API

• bpo-33817: Fixed _PyBytes_Resize() for empty bytes objects.

Python 3.7.2 final

Release date: 2018-12-23

Library

• bpo-31715: Associate .mjs file extension with application/javascript MIME Type.

Build

• bpo-35499: make profile-opt no longer replaces CFLAGS_NODIST with CFLAGS. It now adds profile-guided optimization (PGO) flags to CFLAGS_NODIST: existing CFLAGS_NODIST flags are kept.

• bpo-35257: Avoid leaking the linker flags from Link Time Optimizations (LTO) into distutils when compiling C extensions.

C API

• bpo-35259: Conditionally declare Py_FinalizeEx() (new in 3.6) based on Py_LIMITED_API. Patch by Arthur Neufeld.

Python 3.7.2 release candidate 1

Release date: 2018-12-11

Security

• bpo-34812: The -I command line option (run Python in isolated mode) is now also copied by the multiprocessing and distutils modules when spawning child processes. Previously, only -E and -s options (enabled by -I) were copied.

• bpo-34791: The xml.sax and xml.dom.domreg no longer use environment variables to override parser implementations when sys.flags.ignore_environment is set by -E or -I arguments.

Core and Builtins

• bpo-35444: Fixed error handling in pickling methods when fail to look up builtin “getattr”.

• bpo-35436: Fix various issues with memory allocation error handling. Patch by Zackery Spytz.

• bpo-35357: Internal attributes’ names of unittest.mock._Call and unittest.mock.MagicProxy (name, parent & from_kall) are now prefixed with _mock_ in order to prevent clashes with widely used object attributes. Fixed minor typo in test function name.

• bpo-35372: Fixed the code page decoder for input longer than 2 GiB containing undecodable bytes.

• bpo-35336: Fix PYTHONCOERCECLOCALE=1 environment variable: only coerce the C locale if the LC_CTYPE locale is “C”.

• bpo-33954: For str.format(), float.__format__() and complex.__format__() methods for non-ASCII decimal point when using the “n” formatter.

• bpo-35269: Fix a possible segfault involving a newly-created coroutine. Patch by Zackery Spytz.

• bpo-35214: Fixed an out of bounds memory access when parsing a truncated unicode escape sequence at the end of a string such as '\N'. It would read one byte beyond the end of the memory allocation.

• bpo-35214: The interpreter and extension modules have had annotations added so that they work properly under clang’s Memory Sanitizer. A new configure flag –with-memory-sanitizer has been added to make test builds of this nature easier to perform.

• bpo-35193: Fix an off by one error in the bytecode peephole optimizer where it could read bytes beyond the end of bounds of an array when removing unreachable code. This bug was present in every release of Python 3.6 and 3.7 until now.

• bpo-29341: Clarify in the docstrings of os methods that path-like objects are also accepted as input parameters.

• bpo-35050: socket: Fix off-by-one bug in length check for AF_ALG name and type.

• bpo-34974: bytes and bytearray constructors no longer convert unexpected exceptions (e.g. MemoryError and KeyboardInterrupt) to TypeError.

• bpo-34973: Fixed crash in bytes() when the list argument is mutated while it is iterated.

• bpo-34824: Fix a possible null pointer dereference in Modules/_ssl.c. Patch by Zackery Spytz.

• bpo-1621: Do not assume signed integer overflow behavior (C undefined behavior) when performing set hash table resizing.

Library

• bpo-35052: Fix xml.dom.minidom cloneNode() on a document with an entity: pass the correct arguments to the user data handler of an entity.

• bpo-35330: When a Mock instance was used to wrap an object, if side_effect is used in one of the mocks of it methods, don’t call the original implementation and return the result of using the side effect the same way that it is done with return_value.

• bpo-34172: Revert the fix for this issue previously released in 3.7.1 pending further investigation: Fix a reference issue inside multiprocessing.Pool that caused the pool to remain alive if it was deleted without being closed or terminated explicitly.

• bpo-10496: posixpath.expanduser() now returns the input path unchanged if the HOME environment variable is not set and the current user has no home directory (if the current user identifier doesn’t exist in the password database). This change fix the site module if the current user doesn’t exist in the password database (if the user has no home directory).

• bpo-35310: Fix a bug in select.select() where, in some cases, the file descriptor sequences were returned unmodified after a signal interruption, even though the file descriptors might not be ready yet. select.select() will now always return empty lists if a timeout has occurred. Patch by Oran Avraham.

• bpo-35380: Enable TCP_NODELAY on Windows for proactor asyncio event loop.

• bpo-35341: Add generic version of collections.OrderedDict to the typing module. Patch by Ismo Toijala.

• bpo-35371: Fixed possible crash in os.utime() on Windows when pass incorrect arguments.

• bpo-27903: Fix ResourceWarning in platform.dist() on SuSE and Caldera OpenLinux. Patch by Ville Skyttä.

• bpo-35308: Fix regression in webbrowser where default browsers may be preferred over browsers in the BROWSER environment variable.

• bpo-28604: locale.localeconv() now sets temporarily the LC_CTYPE locale to the LC_MONETARY locale if the two locales are different and monetary strings are non-ASCII. This temporary change affects other threads.

• bpo-35277: Update ensurepip to install pip 18.1 and setuptools 40.6.2.

• bpo-35226: Recursively check arguments when testing for equality of unittest.mock.call objects and add note that tracking of parameters used to create ancestors of mocks in mock_calls is not possible.

• bpo-29564: The warnings module now suggests to enable tracemalloc if the source is specified, the tracemalloc module is available, but tracemalloc is not tracing memory allocations.

• bpo-35189: Modify the following fnctl function to retry if interrupted by a signal (EINTR): flock, lockf, fnctl

• bpo-35062: Fix incorrect parsing of _io.IncrementalNewlineDecoder’s translate argument.

• bpo-35079: Improve difflib.SequenceManager.get_matching_blocks doc by adding ‘non-overlapping’ and changing ‘!=’ to ‘<’.

• bpo-35017: socketserver.BaseServer.serve_forever() now exits immediately if it’s shutdown() method is called while it is polling for new events.

• bpo-31047: Fix ntpath.abspath regression where it didn’t remove a trailing separator on Windows. Patch by Tim Graham.

• bpo-34794: Fixed a leak in Tkinter when pass the Python wrapper around Tcl_Obj back to Tcl/Tk.

• bpo-35008: Fixed references leaks when call the __setstate__() method of xml.etree.ElementTree.Element in the C implementation for already initialized element.

• bpo-23420: Verify the value for the parameter ‘-s’ of the cProfile CLI. Patch by Robert Kuska

• bpo-33947: dataclasses now handle recursive reprs without raising RecursionError.

• bpo-16965: The 2to3 execfile fixer now opens the file with mode 'rb'. Patch by Zackery Spytz.

• bpo-34966: pydoc now supports aliases not only to methods defined in the end class, but also to inherited methods. The docstring is not duplicated for aliases.

• bpo-34941: Methods find(), findtext() and findall() of the Element class in the xml.etree.ElementTree module are now able to find children which are instances of Element subclasses.

• bpo-34936: Fix TclError in tkinter.Spinbox.selection_element(). Patch by Juliette Monsel.

• bpo-34866: Adding max_num_fields to cgi.FieldStorage to make DOS attacks harder by limiting the number of MiniFieldStorage objects created by FieldStorage.

• bpo-34022: The SOURCE_DATE_EPOCH environment variable no longer overrides the value of the invalidation_mode argument to py_compile.compile(), and determines its default value instead.

• bpo-34738: ZIP files created by distutils will now include entries for directories.

• bpo-31177: Fix bug that prevented using reset_mock on mock instances with deleted attributes

• bpo-34536: Enum._missing_: raise ValueError if None returned and TypeError if non-member is returned.

• bpo-34604: Fix possible mojibake in the error message of pwd.getpwnam and grp.getgrnam using string representation because of invisible characters or trailing whitespaces. Patch by William Grzybowski.

• bpo-34574: OrderedDict iterators are not exhausted during pickling anymore. Patch by Sergey Fedoseev.

• bpo-34052: sqlite3.Connection.create_aggregate(), sqlite3.Connection.create_function(), sqlite3.Connection.set_authorizer(), sqlite3.Connection.set_progress_handler() methods raises TypeError when unhashable objects are passed as callable. These methods now don’t pass such objects to SQLite API. Previous behavior could lead to segfaults. Patch by Sergey Fedoseev.

• bpo-29877: compileall: import ProcessPoolExecutor only when needed, preventing hangs on low resource platforms

• bpo-22005: Implemented unpickling instances of datetime, date and time pickled by Python 2. encoding='latin1' should be used for successful decoding.

Documentation

• bpo-35089: Remove mention of typing.io and typing.re. Their types should be imported from typing directly.

• bpo-35038: Fix the documentation about an unexisting f_restricted attribute in the frame object. Patch by Stéphane Wirtel

• bpo-35044: Fix the documentation with the role exc for the appropriated exception. Patch by Stéphane Wirtel

• bpo-35035: Rename documentation for email.utils to email.utils.rst.

• bpo-34967: Use app.add_object_type() instead of the deprecated Sphinx function app.description_unit()

• bpo-11233: Create availability directive for documentation. Original patch by Georg Brandl.

• bpo-33594: Document getargspec, from_function and from_builtin as deprecated in their respective docstring, and include version since deprecation in DeprecationWarning message.

• bpo-32613: Update the faq/windows.html to use the py command from PEP 397 instead of python.

Tests

• bpo-33725: test_multiprocessing_fork may crash on recent versions of macOS. Until the issue is resolved, skip the test on macOS.

• bpo-35352: Modify test_asyncio to use the certificate set from the test directory.

• bpo-35317: Fix mktime() overflow error in test_email: run test_localtime_daylight_true_dst_true() and test_localtime_daylight_false_dst_true() with a specific timezone.

• bpo-21263: After several reports that test_gdb does not work properly on macOS and since gdb is not shipped by default anymore, test_gdb is now skipped on macOS when LLVM Clang has been used to compile Python. Patch by Lysandros Nikolaou

• bpo-34279: regrtest issue a warning when no tests have been executed in a particular test file. Also, a new final result state is issued if no test have been executed across all test files. Patch by Pablo Galindo.

Build

• bpo-35296: The Windows installer (MSI) now also install internal header files (Include/internal/ subdirectory).

• bpo-35351: When building Python with clang and LTO, LTO flags are no longer passed into CFLAGS to build third-party C extensions through distutils.

• bpo-35139: Fix a compiler error when statically linking pyexpat in Modules/Setup.

• bpo-35011: Restores the use of pyexpatns.h to isolate our embedded copy of the expat C library so that its symbols do not conflict at link or dynamic loading time with an embedding application or other extension modules with their own version of libexpat.

• bpo-28015: Have –with-lto works correctly with clang.

• bpo-33015: Fix an undefined behaviour in the pthread implementation of PyThread_start_new_thread(): add a function wrapper to always return NULL.

Windows

• bpo-35401: Updates Windows build to OpenSSL 1.1.0j

• bpo-34977: venv on Windows will now use a python.exe redirector rather than copying the actual binaries from the base environment.

• bpo-34977: Adds support for building a Windows App Store package

• bpo-35067: Remove _distutils_findvs module and use vswhere.exe instead.

• bpo-34532: Fixes exit code of list version arguments for py.exe.

• bpo-32890: Fix usage of GetLastError() instead of errno in os.execve() and os.truncate().

macOS

• bpo-35402: Update macOS installer to use Tcl/Tk 8.6.9.1. [NOTE: This change was reverted for the released python.org 3.7.2 macOS installers due to regressions found in Tk 8.6.9.1. For now, the installers provide Tcl/Tk 8.6.8.]

• bpo-35401: Update macOS installer to use OpenSSL 1.1.0j.

• bpo-35025: Properly guard the use of the CLOCK_GETTIME et al. macros in timemodule on macOS.

• bpo-24658: On macOS, fix reading from and writing into a file with a size larger than 2 GiB.

IDLE

• bpo-35213: Where appropriate, use ‘macOS’ in idlelib.

• bpo-34864: On macOS, warn if the system preference “Prefer tabs when opening documents” is set to “Always”.

• bpo-34864: Document two IDLE on MacOS issues. The System Preferences Dock “prefer tabs always” setting disables some IDLE features. Menus are a bit different than as described for Windows and Linux.

• bpo-35202: Remove unused imports from lib/idlelib

• bpo-33000: Document that IDLE’s shell has no line limit. A program that runs indefinitely can overfill memory.

• bpo-23220: Explain how IDLE’s Shell displays output.

• bpo-35099: Improve the doc about IDLE running user code. The section is renamed from “IDLE – console differences” is renamed “Running user code”. It mostly covers the implications of using custom sys.stdxxx objects.

• bpo-35097: Add IDLE doc subsection explaining editor windows. Topics include opening, title and status bar, .py* extension, and running.

• bpo-35093: Document the IDLE document viewer in the IDLE doc. Add a paragraph in “Help and preferences”, “Help sources” subsection.

• bpo-35088: Update idlelib.help.copy_string docstring. We now use git and backporting instead of hg and forward merging.

• bpo-35087: Update idlelib help files for the current doc build. The main change is the elimination of chapter-section numbers.

Tools/Demos

• bpo-34989: python-gdb.py now handles errors on computing the line number of a Python frame.

C API

• bpo-35322: Fix memory leak in PyUnicode_EncodeLocale() and PyUnicode_EncodeFSDefault() on error handling.

• bpo-35296: make install now also installs the internal API: Include/internal/*.h header files.

• bpo-34725: Adds _Py_SetProgramFullPath so embedders may override sys.executable

Python 3.7.1 final

Release date: 2018-10-20

Library

• bpo-34970: Protect tasks weak set manipulation in asyncio.all_tasks()

Python 3.7.1 release candidate 2

Release date: 2018-10-13

Core and Builtins

• bpo-34879: Fix a possible null pointer dereference in bytesobject.c. Patch by Zackery Spytz.

• bpo-34854: Fixed a crash in compiling string annotations containing a lambda with a keyword-only argument that doesn’t have a default value.

• bpo-34320: Fix dict(od) didn’t copy iteration order of OrderedDict.

Library

• bpo-34769: Fix for async generators not finalizing when event loop is in debug mode and garbage collector runs in another thread.

• bpo-34922: Fixed integer overflow in the digest() and hexdigest() methods for the SHAKE algorithm in the hashlib module.

• bpo-34909: Enum: fix grandchildren subclassing when parent mixed with concrete data types.

• bpo-34900: Fixed unittest.TestCase.debug() when used to call test methods with subtests. Patch by Bruno Oliveira.

• bpo-34871: Fix inspect module polluted sys.modules when parsing __text_signature__ of callable.

• bpo-34872: Fix self-cancellation in C implementation of asyncio.Task

• bpo-34819: Use a monotonic clock to compute timeouts in Executor.map() and as_completed(), in order to prevent timeouts from deviating when the system clock is adjusted.

• bpo-34521: Use socket.CMSG_SPACE() to calculate ancillary data size instead of socket.CMSG_LEN() in multiprocessing.reduction.recvfds() as RFC 3542 requires the use of the former for portable applications.

• bpo-34334: In QueueHandler, clear exc_text from LogRecord to prevent traceback from being written twice.

• bpo-6721: Acquire the logging module’s commonly used internal locks while fork()ing to avoid deadlocks in the child process.

• bpo-34172: Fix a reference issue inside multiprocessing.Pool that caused the pool to remain alive if it was deleted without being closed or terminated explicitly.

Documentation

• bpo-32174: chm document displays non-ASCII charaters properly on some MBCS Windows systems.

Tests

• bpo-32962: Fixed test_gdb when Python is compiled with flags -mcet -fcf-protection -O0.

macOS

• bpo-34370: Revert to using the released Tk 8.6.8 with macOS installers instead of the Tk 8.6.x development snapshot used with 3.7.1rc1 and 3.6.7rc1. The snapshot introduced at least one significant regression (bpo-34927).

C API

• bpo-34910: Ensure that PyObject_Print() always returns -1 on error. Patch by Zackery Spytz.

Python 3.7.1 release candidate 1

Release date: 2018-09-26

Security

• bpo-17239: The xml.sax and xml.dom.minidom parsers no longer processes external entities by default. External DTD and ENTITY declarations no longer load files or create network connections.

• bpo-34623: CVE-2018-14647: The C accelerated _elementtree module now initializes hash randomization salt from _Py_HashSecret instead of libexpat’s default CSPRNG.

• bpo-34405: Updated to OpenSSL 1.1.0i for Windows builds.

• bpo-33871: Fixed sending the part of the file in os.sendfile() on macOS. Using the trailers argument could cause sending more bytes from the input file than was specified.

• bpo-32533: Fixed thread-safety of error handling in _ssl.

Core and Builtins

• bpo-34783: Fix a crash with musl libc (on Alpine Linux) when the script filename specified on the command line doesn’t exist.

• bpo-34762: Fix contextvars C API to use PyObject* pointer types.

• bpo-34735: Fix a memory leak in Modules/timemodule.c. Patch by Zackery Spytz.

• bpo-34588: Fix an off-by-one in the recursive call pruning feature of traceback formatting.

• bpo-34485: Standard streams like sys.stdout now use the “surrogateescape” error handler, instead of “strict”, on the POSIX locale (when the C locale is not coerced and the UTF-8 Mode is disabled).

• bpo-34485: Fix the error handler of standard streams like sys.stdout: PYTHONIOENCODING=”:” is now ignored instead of setting the error handler to “strict”.

• bpo-34527: On FreeBSD, Py_DecodeLocale() and Py_EncodeLocale() now also forces the ASCII encoding if the LC_CTYPE locale is “POSIX”, not only if the LC_CTYPE locale is “C”.

• bpo-34527: The UTF-8 Mode is now also enabled by the “POSIX” locale, not only by the “C” locale.

• bpo-34400: Fix undefined behavior in parsetok.c. Patch by Zackery Spytz.

• bpo-34377: Update valgrind suppression list to use _PyObject_Free/_PyObject_Realloc instead of PyObject_Free/PyObject_Realloc.

• bpo-34170: -X dev: it is now possible to override the memory allocator using PYTHONMALLOC even if the developer mode is enabled.

• bpo-34126: Fix crashes when profiling certain invalid calls of unbound methods. Patch by Jeroen Demeyer.

• bpo-24618: Fixed reading invalid memory when create the code object with too small varnames tuple or too large argument counts.

• bpo-34068: In io.IOBase.close(), ensure that the closed attribute is not set with a live exception. Patch by Zackery Spytz and Serhiy Storchaka.

• bpo-34087: Fix buffer overflow while converting unicode to numeric values.

• bpo-34080: Fixed a memory leak in the compiler when it raised some uncommon errors during tokenizing.

• bpo-34066: Disabled interruption by Ctrl-C between calling open() and entering a with block in with open().

• bpo-34042: Fix dict.copy() to maintain correct total refcount (as reported by sys.gettotalrefcount()).

• bpo-33985: Implement contextvars.ContextVar.name attribute.

• bpo-33956: Update vendored Expat library copy to version 2.2.5.

• bpo-24596: Decref the module object in PyRun_SimpleFileExFlags() before calling PyErr_Print(). Patch by Zackery Spytz.

• bpo-33451: Close directly executed pyc files before calling PyEval_EvalCode().

• bpo-33824: Fix “LC_ALL=C python3.7 -V”: reset properly the command line parser when the encoding changes after reading the Python configuration.

• bpo-25750: Fix rare Python crash due to bad refcounting in type_getattro() if a descriptor deletes itself from the class. Patch by Jeroen Demeyer.

• bpo-31902: Fix the col_offset attribute for ast nodes ast.AsyncFor, ast.AsyncFunctionDef, and ast.AsyncWith. Previously, col_offset pointed to the keyword after async.

• bpo-25862: Fix assertion failures in the tell() method of io.TextIOWrapper. Patch by Zackery Spytz.

• bpo-31577: Fix a crash in os.utime() in case of a bad ns argument. Patch by Oren Milman.

Library

• bpo-29577: Support multiple mixin classes when creating Enums.

• bpo-34670: Add SSLContext.post_handshake_auth and SSLSocket.verify_client_post_handshake for TLS 1.3’s post handshake authentication feature.

• bpo-34658: Fix a rare interpreter unhandled exception state SystemError only seen when using subprocess with a preexec_fn while an after_parent handler has been registered with os.register_at_fork and the fork system call fails.

• bpo-34652: Ensure os.lchmod() is never defined on Linux.

• bpo-34363: dataclasses.asdict() and .astuple() now handle namedtuples correctly.

• bpo-34625: Update vendorized expat library version to 2.2.6.

• bpo-34621: Fix un/pickling compatbility of uuid.UUID objects with older versions of Python (<3.7).

• bpo-32270: The subprocess module no longer mistakenly closes redirected fds even when they were in pass_fds when outside of the default {0, 1, 2} set.

• bpo-34610: Fixed iterator of multiprocessing.managers.DictProxy.

• bpo-34421: Fix distutils logging for non-ASCII strings. This caused installation issues on Windows.

• bpo-34604: Fix possible mojibake in the error message of pwd.getpwnam and grp.getgrnam. Patch by William Grzybowski.

• bpo-34530: distutils.spawn.find_executable() now falls back on os.defpath if the PATH environment variable is not set.

• bpo-34282: Fix enum members getting shadowed by parent attributes.

• bpo-34563: On Windows, fix multiprocessing.Connection for very large read: fix _winapi.PeekNamedPipe() and _winapi.ReadFile() for read larger than INT_MAX (usually 2^31-1).

• bpo-34558: Correct typo in Lib/ctypes/_aix.py

• bpo-34515: Fix parsing non-ASCII identifiers in lib2to3.pgen2.tokenize (PEP 3131).

• bpo-13312: Avoids a possible integer underflow (undefined behavior) in the time module’s year handling code when passed a very low negative year value.

• bpo-34472: Improved compatibility for streamed files in zipfile. Previously an optional signature was not being written and certain ZIP applications were not supported. Patch by Silas Sewell.

• bpo-34454: Fix the .fromisoformat() methods of datetime types crashing when given unicode with non-UTF-8-encodable code points. Specifically, datetime.fromisoformat() now accepts surrogate unicode code points used as the separator. Report and tests by Alexey Izbyshev, patch by Paul Ganssle.

• bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks. Patch by Vladimir Matveev.

• bpo-34171: Running the trace module no longer creates the trace.cover file.

• bpo-34441: Fix crash when an ABC-derived class with invalid __subclasses__ is passed as the second argument to issubclass(). Patch by Alexey Izbyshev.

• bpo-34341: Appending to the ZIP archive with the ZIP64 extension no longer grows the size of extra fields of existing entries.

• bpo-34333: Fix %-formatting in pathlib.PurePath.with_suffix() when formatting an error message.

• bpo-18540: The imaplib.IMAP4 and imaplib.IMAP4_SSL classes now resolve to the local host IP correctly when the default value of host parameter ('') is used.

• bpo-34246: smtplib.SMTP.send_message() no longer modifies the content of the mail_options argument. Patch by Pablo S. Blum de Aguiar.

• bpo-31047: Fix ntpath.abspath for invalid paths on windows. Patch by Franz Woellert.

• bpo-34263: asyncio’s event loop will not pass timeouts longer than one day to epoll/select etc.

• bpo-34035: Fix several AttributeError in zipfile seek() methods. Patch by Mickaël Schoentgen.

• bpo-32215: Fix performance regression in sqlite3 when a DML statement appeared in a different line than the rest of the SQL query.

• bpo-34251: Restore msilib.Win64 to preserve backwards compatibility since it’s already used by distutils’ bdist_msi command.

• bpo-19891: Ignore errors caused by missing / non-writable homedir while writing history during exit of an interactive session. Patch by Anthony Sottile.

• bpo-34213: Allow frozen dataclasses to have a field named “object”. Previously this conflicted with an internal use of “object”.

• bpo-21446: The reload fixer now uses importlib.reload() instead of deprecated imp.reload().

• bpo-940286: pydoc’s Helper.showtopic() method now prints the cross references of a topic correctly.

• bpo-34164: base64.b32decode() could raise UnboundLocalError or OverflowError for incorrect padding. Now it always raises base64.Error in these cases.

• bpo-33729: Fixed issues with arguments parsing in hashlib.

• bpo-34108: Remove extraneous CR in 2to3 refactor.

• bpo-27494: Reverted bpo-27494. 2to3 rejects now a trailing comma in generator expressions.

• bpo-33967: functools.singledispatch now raises TypeError instead of IndexError when no positional arguments are passed.

• bpo-34056: Ensure the loader shim created by imp.load_module always returns bytes from its get_data() function. This fixes using imp.load_module with PEP 552 hash-based pycs.

• bpo-34054: The multiprocessing module now uses the monotonic clock time.monotonic() instead of the system clock time.time() to implement timeout.

• bpo-34044: subprocess.Popen now copies the startupinfo argument to leave it unchanged: it will modify the copy, so that the same STARTUPINFO object can be used multiple times.

• bpo-34010: Fixed a performance regression for reading streams with tarfile. The buffered read should use a list, instead of appending to a bytes object.

• bpo-34019: webbrowser: Correct the arguments passed to Opera Browser when opening a new URL using the webbrowser module. Patch by Bumsik Kim.

• bpo-33978: Closed existing logging handlers before reconfiguration via fileConfig and dictConfig. Patch by Karthikeyan Singaravelan.

• bpo-14117: Make minor tweaks to turtledemo. The ‘wikipedia’ example is now ‘rosette’, decribing what it draws. The ‘penrose’ print output is reduced. The’1024’ output of ‘tree’ is eliminated.

• bpo-33974: Fixed passing lists and tuples of strings containing special characters ", \, {, } and \n as options to ttk widgets.

• bpo-27500: Fix getaddrinfo to resolve IPv6 addresses correctly.

• bpo-24567: Improve random.choices() to handle subnormal input weights that could occasionally trigger an IndexError.

• bpo-33871: Fixed integer overflow in os.readv(), os.writev(), os.preadv() and os.pwritev() and in os.sendfile() with headers or trailers arguments (on BSD-based OSes and macOS).

• bpo-33899: Tokenize module now implicitly emits a NEWLINE when provided with input that does not have a trailing new line. This behavior now matches what the C tokenizer does internally. Contributed by Ammar Askar.

• bpo-33916: bz2 and lzma: When Decompressor.__init__() is called twice, free the old lock to not leak memory.

• bpo-32568: Make select.epoll() and its documentation consistent regarding sizehint and flags.

• bpo-33833: Fixed bug in asyncio where ProactorSocketTransport logs AssertionError if force closed during write.

• bpo-33663: Convert content length to string before putting to header.

• bpo-26544: Fixed implementation of platform.libc_ver(). It almost always returned version ‘2.9’ for glibc.

• bpo-33805: Improve error message of dataclasses.replace() when an InitVar is not specified

• bpo-27397: Make email module properly handle invalid-length base64 strings.

• bpo-33476: Fix _header_value_parser.py when address group is missing final ‘;’. Contributed by Enrique Perez-Terron

• bpo-31014: Fixed creating a controller for webbrowser when a user specifies a path to an entry in the BROWSER environment variable. Based on patch by John Still.

• bpo-33365: Print the header values besides the header keys instead just the header keys if debuglevel is set to >0 in http.client. Patch by Marco Strigl.

• bpo-32933: unittest.mock.mock_open() now supports iteration over the file contents. Patch by Tony Flury.

• bpo-33336: imaplib now allows MOVE command in IMAP4.uid() (RFC 6851: IMAP MOVE Extension) and potentially as a name of supported method of IMAP4 object.

• bpo-31608: Raise a TypeError instead of crashing if a collections.deque subclass returns a non-deque from __new__. Patch by Oren Milman.

• bpo-29456: Fix bugs in hangul normalization: u1176, u11a7 and u11c3

Documentation

• bpo-34790: Document how passing coroutines to asyncio.wait() can be confusing.

• bpo-28617: Fixed info in the stdtypes docs concerning the types that support membership tests.

• bpo-34065: Fix wrongly written basicConfig documentation markup syntax

• bpo-33460: replaced ellipsis with correct error codes in tutorial chapter 3.

• bpo-33847: Add ‘@’ operator entry to index.

• bpo-25041: Document AF_PACKET in the socket module.

Tests

• bpo-34537: Fix test_gdb.test_strings() when LC_ALL=C and GDB was compiled with Python 3.6 or earlier.

• bpo-34587: test_socket: Remove RDSTest.testCongestion(). The test tries to fill the receiver’s socket buffer and expects an error. But the RDS protocol doesn’t require that. Moreover, the Linux implementation of RDS expects that the producer of the messages reduces its rate, it’s not the role of the receiver to trigger an error. The test fails on Fedora 28 by design, so just remove it.

• bpo-34661: Fix test_shutil if unzip doesn’t support -t.

• bpo-34200: Fixed non-deterministic flakiness of test_pkg by not using the scary test.support.module_cleanup() logic to save and restore sys.modules contents between test cases.

• bpo-34594: Fix usage of hardcoded errno values in the tests.

• bpo-34542: Use 3072 RSA keys and SHA-256 signature for test certs and keys.

• bpo-11193: Remove special condition for AIX in test_subprocess.test_undecodable_env

• bpo-34490: On AIX with AF_UNIX family sockets getsockname() does not provide ‘sockname’, so skip calls to transport.get_extra_info(‘sockname’)

• bpo-34391: Fix ftplib test for TLS 1.3 by reading from data socket.

• bpo-34399: Update all RSA keys and DH params to use at least 2048 bits.

• bpo-33746: Fix test_unittest when run in verbose mode.

• bpo-33901: Fix test_dbm_gnu on macOS with gdbm 1.15: add a larger value to make sure that the file size changes.

• bpo-33873: Fix a bug in regrtest that caused an extra test to run if –huntrleaks/-R was used. Exit with error in case that invalid parameters are specified to –huntrleaks/-R (at least one warmup run and one repetition must be used).

• bpo-32663: Making sure the SMTPUTF8SimTests class of tests gets run in test_smtplib.py.

Build

• bpo-34710: Fixed SSL module build with OpenSSL & pedantic CFLAGS.

• bpo-34582: Add JUnit XML output for regression tests and update Azure DevOps builds.

• bpo-34555: Fix for case where it was not possible to have both HAVE_LINUX_VM_SOCKETS_H and HAVE_SOCKADDR_ALG be undefined.

• bpo-34121: Fix detection of C11 atomic support on clang.

• bpo-30345: Add -g to LDFLAGS when compiling with LTO to get debug symbols.

• bpo-33648: The –with-c-locale-warning configuration flag has been removed. It has had no effect for about a year.

Windows

• bpo-34770: Fix a possible null pointer dereference in pyshellext.cpp.

• bpo-34603: Fix returning structs from functions produced by MSVC

• bpo-34581: Guard MSVC-specific code in socketmodule.c with #ifdef _MSC_VER.

• bpo-34062: Fixed the ‘–list’ and ‘–list-paths’ arguments for the py.exe launcher

• bpo-34225: Ensure INCLUDE and LIB directories do not end with a backslash.

• bpo-34006: Revert line length limit for Windows help docs. The line-length limit is not needed because the pages appear in a separate app rather than on a browser tab. It can also interact badly with the DPI setting.

• bpo-31546: Restore running PyOS_InputHook while waiting for user input at the prompt. The restores integration of interactive GUI windows (such as Matplotlib figures) with the prompt on Windows.

• bpo-30237: Output error when ReadConsole is canceled by CancelSynchronousIo instead of crashing.

• bpo-29097: Fix bug where datetime.fromtimestamp() erronously throws an OSError on Windows for values between 0 and 86400. Patch by Ammar Askar.

macOS

• bpo-34370: Have macOS 10.9+ installer builds for 3.7.1rc and 3.6.7rc use a development snapshot of Tk 8.6 (post-8.6.8) to mitigate certain scroller issues seen with IDLE and tkinter apps.

• bpo-34405: Update to OpenSSL 1.1.0i for macOS installer builds.

• bpo-33635: In macOS stat on some file descriptors (/dev/fd/3 f.e) will result in bad file descriptor OSError. Guard against this exception was added in is_dir, is_file and similar methods. DirEntry.is_dir can also throw this exception so _RecursiveWildcardSelector._iterate_directories was also extended with the same error ignoring pattern.

• bpo-31903: In _scproxy, drop the GIL when calling into SystemConfiguration to avoid deadlocks.

IDLE

• bpo-34548: Use configured color theme for read-only text views.

• bpo-1529353: Enable “squeezing” of long outputs in the shell, to avoid performance degradation and to clean up the history without losing it. Squeezed outputs may be copied, viewed in a separate window, and “unsqueezed”.

• bpo-34047: Fixed mousewheel scrolling direction on macOS.

• bpo-34275: Make IDLE calltips always visible on Mac. Some MacOS-tk combinations need .update_idletasks(). Patch by Kevin Walzer.

• bpo-34120: Fix unresponsiveness after closing certain windows and dialogs.

• bpo-33975: Avoid small type when running htests. Since part of the purpose of human-viewed tests is to determine that widgets look right, it is important that they look the same for testing as when running IDLE.

• bpo-33905: Add test for idlelib.stackview.StackBrowser.

• bpo-33924: Change mainmenu.menudefs key ‘windows’ to ‘window’. Every other menudef key is lowercase version of main menu entry.

• bpo-33906: Rename idlelib.windows as window Match Window on the main menu and remove last plural module name.

• bpo-33917: Fix and document idlelib/idle_test/template.py. The revised file compiles, runs, and tests OK. idle_test/README.txt explains how to use it to create new IDLE test files.

• bpo-33904: IDLE: In rstrip, rename class RstripExtension as Rstrip

• bpo-33907: For consistency and clarity, rename an IDLE module and classes. Module calltips and its class CallTips are now calltip and Calltip. In module calltip_w, class CallTip is now CalltipWindow.

• bpo-33856: Add “help” in the welcome message of IDLE

• bpo-33839: IDLE: refactor ToolTip and CallTip and add documentation and tests

• bpo-33855: Minimally test all IDLE modules. Add missing files, import module, instantiate classes, and check coverage. Check existing files.

Tools/Demos

• bpo-32962: python-gdb now catches UnicodeDecodeError exceptions when calling string().

• bpo-32962: python-gdb now catches ValueError on read_var(): when Python has no debug symbols for example.

C API

• bpo-34247: Fix Py_Initialize() regression introduced in 3.7.0: read environment variables like PYTHONOPTIMIZE.

• bpo-23927: Fixed SystemError in PyArg_ParseTupleAndKeywords() when the w* format unit is used for optional parameter.

• bpo-34008: Py_Main() can again be called after Py_Initialize(), as in Python 3.6.

Python 3.7.0 final

Release date: 2018-06-27

Library

• bpo-33851: Fix ast.get_docstring() for a node that lacks a docstring.

C API

• bpo-33932: Calling Py_Initialize() twice does nothing, instead of failing with a fatal error: restore the Python 3.6 behaviour.

Python 3.7.0 release candidate 1

Release date: 2018-06-12

Core and Builtins

• bpo-33803: Fix a crash in hamt.c caused by enabling GC tracking for an object that hadn’t all of its fields set to NULL.

• bpo-33706: Fix a crash in Python initialization when parsing the command line options. Thanks Christoph Gohlke for the bug report and the fix!

• bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on interpreter shutdown even when there was a custom handler set previously. Patch by Philipp Kerling.

• bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

Library

• bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set. Patch by Steve Weber.

• bpo-33812: Datetime instance d with non-None tzinfo, but with d.tzinfo.utcoffset(d) returning None is now treated as naive by the astimezone() method.

• bpo-30805: Avoid race condition with debug logging

• bpo-33694: asyncio: Fix a race condition causing data loss on pause_reading()/resume_reading() when using the ProactorEventLoop.

• bpo-32493: Correct test for uuid_enc_be availability in configure.ac. Patch by Michael Felt.

• bpo-33792: Add asyncio.WindowsSelectorEventLoopPolicy and asyncio.WindowsProactorEventLoopPolicy.

• bpo-33778: Update unicodedata’s database to Unicode version 11.0.0.

• bpo-33770: improve base64 exception message for encoded inputs of invalid length

• bpo-33769: asyncio/start_tls: Fix error message; cancel callbacks in case of an unhandled error; mark SSLTransport as closed if it is aborted.

• bpo-33767: The concatenation (+) and repetition (*) sequence operations now raise TypeError instead of SystemError when performed on mmap.mmap objects. Patch by Zackery Spytz.

• bpo-33734: asyncio/ssl: Fix AttributeError, increase default handshake timeout

• bpo-11874: Use a better regex when breaking usage into wrappable parts. Avoids bogus assertion errors from custom metavar strings.

• bpo-33582: Emit a deprecation warning for inspect.formatargspec

Documentation

• bpo-33409: Clarified the relationship between PEP 538’s PYTHONCOERCECLOCALE and PEP 540’s PYTHONUTF8 mode.

• bpo-33736: Improve the documentation of asyncio.open_connection(), asyncio.start_server() and their UNIX socket counterparts.

• bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and CERT_REQUIRED flags for ssl.SSLContext.verify_mode.

Build

• bpo-5755: Move -Wstrict-prototypes option to CFLAGS_NODIST from OPT. This option emitted annoying warnings when building extension modules written in C++.

Windows

• bpo-33720: Reduces maximum marshal recursion depth on release builds.

IDLE

• bpo-33656: On Windows, add API call saying that tk scales for DPI. On Windows 8.1+ or 10, with DPI compatibility properties of the Python binary unchanged, and a monitor resolution greater than 96 DPI, this should make text and lines sharper. It should otherwise have no effect.

• bpo-33768: Clicking on a context line moves that line to the top of the editor window.

• bpo-33763: IDLE: Use read-only text widget for code context instead of label widget.

• bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse wheel and scrollbar slider moved text by a fixed number of pixels, resulting in partial lines at the top of the editor box. The change also applies to the shell and grep output windows, but not to read-only text views.

• bpo-33679: Enable theme-specific color configuration for Code Context. Use the Highlights tab to see the setting for built-in themes or add settings to custom themes.

• bpo-33642: Display up to maxlines non-blank lines for Code Context. If there is no current context, show a single blank line.

Python 3.7.0 beta 5

Release date: 2018-05-30

Core and Builtins

• bpo-33622: Fixed a leak when the garbage collector fails to add an object with the __del__ method or referenced by it into the gc.garbage list. PyGC_Collect() can now be called when an exception is set and preserves it.

• bpo-33509: Fix module_globals parameter of warnings.warn_explicit(): don’t crash if module_globals is not a dict.

• bpo-20104: The new os.posix_spawn added in 3.7.0b1 was removed as we are still working on what the API should look like. Expect this in 3.8 instead.

• bpo-33475: Fixed miscellaneous bugs in converting annotations to strings and optimized parentheses in the string representation.

• bpo-33391: Fix a leak in set_symmetric_difference().

• bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike Beer.

• bpo-32911: Due to unexpected compatibility issues discovered during downstream beta testing, reverted bpo-29463. docstring field is removed from Module, ClassDef, FunctionDef, and AsyncFunctionDef ast nodes which was added in 3.7a1. Docstring expression is restored as a first statement in their body. Based on patch by Inada Naoki.

• bpo-21983: Fix a crash in ctypes.cast() in case the type argument is a ctypes structured data type. Patch by Eryk Sun and Oren Milman.

Library

• bpo-32751: When cancelling the task due to a timeout, asyncio.wait_for() will now wait until the cancellation is complete.

• bpo-32684: Fix gather to propagate cancellation of itself even with return_exceptions.

• bpo-33654: Support protocol type switching in SSLTransport.set_protocol().

• bpo-33674: Pause the transport as early as possible to further reduce the risk of data_received() being called before connection_made().

• bpo-33674: Fix a race condition in SSLProtocol.connection_made() of asyncio.sslproto: start immediately the handshake instead of using call_soon(). Previously, data_received() could be called before the handshake started, causing the handshake to hang or fail.

• bpo-31647: Fixed bug where calling write_eof() on a _SelectorSocketTransport after it’s already closed raises AttributeError.

• bpo-32610: Make asyncio.all_tasks() return only pending tasks.

• bpo-32410: Avoid blocking on file IO in sendfile fallback code

• bpo-33469: Fix RuntimeError after closing loop that used run_in_executor

• bpo-33672: Fix Task.__repr__ crash with Cython’s bogus coroutines

• bpo-33654: Fix transport.set_protocol() to support switching between asyncio.Protocol and asyncio.BufferedProtocol. Fix loop.start_tls() to work with asyncio.BufferedProtocols.

• bpo-33652: Pickles of type variables and subscripted generics are now future-proof and compatible with older Python versions.

• bpo-32493: Fixed uuid.uuid1() on FreeBSD.

• bpo-33618: Finalize and document preliminary and experimental TLS 1.3 support with OpenSSL 1.1.1

• bpo-33623: Fix possible SIGSGV when asyncio.Future is created in __del__

• bpo-30877: Fixed a bug in the Python implementation of the JSON decoder that prevented the cache of parsed strings from clearing after finishing the decoding. Based on patch by c-fos.

• bpo-33570: Change TLS 1.3 cipher suite settings for compatibility with OpenSSL 1.1.1-pre6 and newer. OpenSSL 1.1.1 will have TLS 1.3 ciphers enabled by default.

• bpo-28556: Do not simplify arguments to typing.Union. Now Union[Manager, Employee] is not simplified to Employee at runtime. Such simplification previously caused several bugs and limited possibilities for introspection.

• bpo-33540: Add a new block_on_close class attribute to ForkingMixIn and ThreadingMixIn classes of socketserver.

• bpo-33548: tempfile._candidate_tempdir_list should consider common TEMP locations

• bpo-33109: argparse subparsers are once again not required by default, reverting the change in behavior introduced by bpo-26510 in 3.7.0a2.

• bpo-33536: dataclasses.make_dataclass now checks for invalid field names and duplicate fields. Also, added a check for invalid field specifications.

• bpo-33542: Prevent uuid.get_node from using a DUID instead of a MAC on Windows. Patch by Zvi Effron

• bpo-26819: Fix race condition with ReadTransport.resume_reading in Windows proactor event loop.

• Fix failure in typing.get_type_hints() when ClassVar was provided as a string forward reference.

• bpo-33505: Optimize asyncio.ensure_future() by reordering if checks: 1.17x faster.

• bpo-33497: Add errors param to cgi.parse_multipart and make an encoding in FieldStorage use the given errors (needed for Twisted). Patch by Amber Brown.

• bpo-33495: Change dataclasses.Fields repr to use the repr of each of its members, instead of str. This makes it more clear what each field actually represents. This is especially true for the ‘type’ member.

• bpo-33453: Fix dataclasses to work if using literal string type annotations or if using PEP 563 “Postponed Evaluation of Annotations”. Only specific string prefixes are detected for both ClassVar (“ClassVar” and “typing.ClassVar”) and InitVar (“InitVar” and “dataclasses.InitVar”).

• bpo-28556: Minor fixes in typing module: add annotations to NamedTuple.__new__, pass *args and **kwds in Generic.__new__. Original PRs by Paulius Šarka and Chad Dombrova.

• bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

• bpo-33422: Fix trailing quotation marks getting deleted when looking up byte/string literals on pydoc. Patch by Andrés Delfino.

• bpo-28167: The function platform.linux_distribution and platform.dist now trigger a DeprecationWarning and have been marked for removal in Python 3.8

• bpo-33197: Update error message when constructing invalid inspect.Parameters Patch by Dong-hee Na.

• bpo-33263: Fix FD leak in _SelectorSocketTransport Patch by Vlad Starostin.

• bpo-32861: The urllib.robotparser’s __str__ representation now includes wildcard entries and the “Crawl-delay” and “Request-rate” fields. Patch by Michael Lazar.

• bpo-32257: The ssl module now contains OP_NO_RENEGOTIATION constant, available with OpenSSL 1.1.0h or 1.1.1.

• bpo-16865: Support arrays >=2GiB in ctypes. Patch by Segev Finer.

Documentation

• bpo-23859: Document that asyncio.wait() does not cancel its futures on timeout.

• bpo-32436: Document PEP 567 changes to asyncio.

• bpo-33604: Update HMAC md5 default to a DeprecationWarning, bump removal to 3.8.

• bpo-33503: Fix broken pypi link

• bpo-33421: Add missing documentation for typing.AsyncContextManager.

Tests

• bpo-33655: Ignore test_posix_fallocate failures on BSD platforms that might be due to running on ZFS.

• bpo-32604: Remove the _xxsubinterpreters module (meant for testing) and associated helpers. This module was originally added recently in 3.7b1.

Build

• bpo-33614: Ensures module definition files for the stable ABI on Windows are correctly regenerated.

• bpo-33522: Enable CI builds on Visual Studio Team Services at https://python.visualstudio.com/cpython

• bpo-33012: Add -Wno-cast-function-type for gcc 8 for silencing warnings about function casts like casting to PyCFunction in method definition lists.

macOS

• bpo-13631: The .editrc file in user’s home directory is now processed correctly during the readline initialization through editline emulation on macOS.

IDLE

• bpo-33628: IDLE: Cleanup codecontext.py and its test.

• bpo-33564: IDLE’s code context now recognizes async as a block opener.

• bpo-32831: Add docstrings and tests for codecontext.

Python 3.7.0 beta 4

Release date: 2018-05-02

Core and Builtins

• bpo-33363: Raise a SyntaxError for async with and async for statements outside of async functions.

• bpo-33128: Fix a bug that causes PathFinder to appear twice on sys.meta_path. Patch by Pablo Galindo Salgado.

• bpo-33312: Fixed clang ubsan (undefined behavior sanitizer) warnings in dictobject.c by adjusting how the internal struct _dictkeysobject shared keys structure is declared.

• bpo-33231: Fix potential memory leak in normalizestring().

• bpo-33205: Change dict growth function from round_up_to_power_2(used*2+hashtable_size/2) to round_up_to_power_2(used*3). Previously, dict is shrinked only when used == 0. Now dict has more chance to be shrinked.

• bpo-29922: Improved error messages in ‘async with’ when __aenter__() or __aexit__() return non-awaitable object.

• bpo-33199: Fix ma_version_tag in dict implementation is uninitialized when copying from key-sharing dict.

Library

• bpo-33281: Fix ctypes.util.find_library regression on macOS.

• bpo-33383: Fixed crash in the get() method of the dbm.ndbm database object when it is called with a single argument.

• bpo-33329: Fix multiprocessing regression on newer glibcs

• bpo-991266: Fix quoting of the Comment attribute of http.cookies.SimpleCookie.

• bpo-33131: Upgrade bundled version of pip to 10.0.1.

• bpo-33308: Fixed a crash in the parser module when converting an ST object to a tree of tuples or lists with line_info=False and col_info=True.

• bpo-33266: lib2to3 now recognizes rf'...' strings.

• bpo-11594: Ensure line-endings are respected when using lib2to3.

• bpo-33254: Have importlib.resources.contents() and importlib.abc.ResourceReader.contents() return an iterable instead of an iterator.

• bpo-33256: Fix display of <module> call in the html produced by cgitb.html(). Patch by Stéphane Blondon.

• bpo-33185: Fixed regression when running pydoc with the -m switch. (The regression was introduced in 3.7.0b3 by the resolution of bpo-33053)

  This fix also changed pydoc to add os.getcwd() to sys.path when necessary, rather than adding ".".

• bpo-33169: Delete entries of None in sys.path_importer_cache when importlib.machinery.invalidate_caches() is called.

• bpo-33217: Deprecate looking up non-Enum objects in Enum classes and Enum members (will raise TypeError in 3.8+).

• bpo-33203: random.Random.choice() now raises IndexError for empty sequences consistently even when called from subclasses without a getrandbits() implementation.

• bpo-33224: Update difflib.mdiff() for PEP 479. Convert an uncaught StopIteration in a generator into a return-statement.

• bpo-33209: End framing at the end of C implementation of pickle.Pickler.dump().

• bpo-20104: Improved error handling and fixed a reference leak in os.posix_spawn().

• bpo-33175: In dataclasses, Field.__set_name__ now looks up the __set_name__ special method on the class, not the instance, of the default value.

• bpo-33097: Raise RuntimeError when executor.submit is called during interpreter shutdown.

• bpo-31908: Fix output of cover files for trace module command-line tool. Previously emitted cover files only when --missing option was used. Patch by Michael Selik.

Documentation

• bpo-33378: Add Korean language switcher for https://docs.python.org/3/

• bpo-33276: Clarify that the __path__ attribute on modules cannot be just any value.

• bpo-33201: Modernize documentation for writing C extension types.

• bpo-33195: Deprecate Py_UNICODE usage in c-api/arg document. Py_UNICODE related APIs are deprecated since Python 3.3, but it is missed in the document.

• bpo-8243: Add a note about curses.addch and curses.addstr exception behavior when writing outside a window, or pad.

• bpo-32337: Update documentation related with dict order.

Tests

• bpo-33358: Fix test_embed.test_pre_initialization_sys_options() when the interpreter is built with --enable-shared.

Build

• bpo-33394: Enable the verbose build for extension modules, when GNU make is passed macros on the command line.

• bpo-33393: Update config.guess and config.sub files.

• bpo-33377: Add new triplets for mips r6 and riscv variants (used in extension suffixes).

• bpo-32232: By default, modules configured in Modules/Setup are no longer built with -DPy_BUILD_CORE. Instead, modules that specifically need that preprocessor definition include it in their individual entries.

• bpo-33182: The embedding tests can once again be built with clang 6.0

Windows

• bpo-33184: Update Windows installer to use OpenSSL 1.1.0h.

macOS

• bpo-33184: Update macOS installer build to use OpenSSL 1.1.0h.

IDLE

• bpo-21474: Update word/identifier definition from ascii to unicode. In text and entry boxes, this affects selection by double-click, movement left/right by control-left/right, and deletion left/right by control-BACKSPACE/DEL.

• bpo-33204: IDLE: consistently color invalid string prefixes. A ‘u’ string prefix cannot be paired with either ‘r’ or ‘f’. Consistently color as much of the prefix, starting at the right, as is valid. Revise and extend colorizer test.

Tools/Demos

• bpo-33189: pygettext.py now recognizes only literal strings as docstrings and translatable strings, and rejects bytes literals and f-string expressions.

• bpo-31920: Fixed handling directories as arguments in the pygettext script. Based on patch by Oleg Krasnikov.

• bpo-29673: Fix pystackv and pystack gdbinit macros.

• bpo-31583: Fix 2to3 for using with –add-suffix option but without –output-dir option for relative path to files in current directory.

Python 3.7.0 beta 3

Release date: 2018-03-29

Security

• bpo-33136: Harden ssl module against LibreSSL CVE-2018-8970. X509_VERIFY_PARAM_set1_host() is called with an explicit namelen. A new test ensures that NULL bytes are not allowed.

• bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on Windows

• bpo-32981: Regexes in difflib and poplib were vulnerable to catastrophic backtracking. These regexes formed potential DOS vectors (REDOS). They have been refactored. This resolves CVE-2018-1060 and CVE-2018-1061. Patch by Jamie Davis.

Core and Builtins

• bpo-33053: When using the -m switch, sys.path[0] is now explicitly expanded as the starting working directory, rather than being left as the empty path (which allows imports from the current working directory at the time of the import)

• bpo-33018: Improve consistency of errors raised by issubclass() when called with a non-class and an abstract base class as the first and second arguments, respectively. Patch by Josh Bronson.

• bpo-33041: Fixed jumping when the function contains an async for loop.

• bpo-33026: Fixed jumping out of “with” block by setting f_lineno.

• bpo-33005: Fix a crash on fork when using a custom memory allocator (ex: using PYTHONMALLOC env var). _PyGILState_Reinit() and _PyInterpreterState_Enable() now use the default RAW memory allocator to allocate a new interpreters mutex on fork.

• bpo-17288: Prevent jumps from ‘return’ and ‘exception’ trace events.

• bpo-32836: Don’t use temporary variables in cases of list/dict/set comprehensions

Library

• bpo-33141: Have Field objects pass through __set_name__ to their default values, if they have their own __set_name__.

• bpo-33096: Allow ttk.Treeview.insert to insert iid that has a false boolean value. Note iid=0 and iid=False would be same. Patch by Garvit Khatri.

• bpo-32873: Treat type variables and special typing forms as immutable by copy and pickle. This fixes several minor issues and inconsistencies, and improves backwards compatibility with Python 3.6.

• bpo-33134: When computing dataclass’s __hash__, use the lookup table to contain the function which returns the __hash__ value. This is an improvement over looking up a string, and then testing that string to see what to do.

• bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

• bpo-32505: Raise TypeError if a member variable of a dataclass is of type Field, but doesn’t have a type annotation.

• bpo-33078: Fix the failure on OSX caused by the tests relying on sem_getvalue

• bpo-33116: Add ‘Field’ to dataclasses.__all__.

• bpo-32896: Fix an error where subclassing a dataclass with a field that uses a default_factory would generate an incorrect class.

• bpo-33100: Dataclasses: If a field has a default value that’s a MemberDescriptorType, then it’s from that field being in __slots__, not an actual default value.

• bpo-32953: If a non-dataclass inherits from a frozen dataclass, allow attributes to be added to the derived class. Only attributes from the frozen dataclass cannot be assigned to. Require all dataclasses in a hierarchy to be either all frozen or all non-frozen.

• bpo-33061: Add missing NoReturn to __all__ in typing.py

• bpo-33078: Fix the size handling in multiprocessing.Queue when a pickling error occurs.

• bpo-33064: lib2to3 now properly supports trailing commas after *args and **kwargs in function signatures.

• bpo-33056: FIX properly close leaking fds in concurrent.futures.ProcessPoolExecutor.

• bpo-33021: Release the GIL during fstat() calls, avoiding hang of all threads when calling mmap.mmap(), os.urandom(), and random.seed(). Patch by Nir Soffer.

• bpo-31804: Avoid failing in multiprocessing.Process if the standard streams are closed or None at exit.

• bpo-33037: Skip sending/receiving data after SSL transport closing.

• bpo-27683: Fix a regression in ipaddress that result of hosts() is empty when the network is constructed by a tuple containing an integer mask and only 1 bit left for addresses.

• bpo-32999: Fix C implementation of ABC.__subclasscheck__(cls, subclass) crashed when subclass is not a type object.

• bpo-33009: Fix inspect.signature() for single-parameter partialmethods.

• bpo-32969: Expose several missing constants in zlib and fix corresponding documentation.

• bpo-32056: Improved exceptions raised for invalid number of channels and sample width when read an audio file in modules aifc, wave and sunau.

• bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to stderr in subprocess if another low descriptor is closed.

• bpo-32857: In tkinter, after_cancel(None) now raises a ValueError instead of canceling the first scheduled function. Patch by Cheryl Sabella.

• bpo-31639: http.server now exposes a ThreadedHTTPServer class and uses it when the module is run with -m to cope with web browsers pre-opening sockets.

• bpo-27645: sqlite3.Connection now exposes a backup method, if the underlying SQLite library is at version 3.6.11 or higher. Patch by Lele Gaifax.

Documentation

• bpo-33126: Document PyBuffer_ToContiguous().

• bpo-27212: Modify documentation for the islice() recipe to consume initial values up to the start index.

• bpo-28247: Update zipapp documentation to describe how to make standalone applications.

• bpo-18802: Documentation changes for ipaddress. Patch by Jon Foster and Berker Peksag.

• bpo-27428: Update documentation to clarify that WindowsRegistryFinder implements MetaPathFinder. (Patch by Himanshu Lakhara)

Tests

• bpo-32872: Avoid regrtest compatibility issue with namespace packages.

• bpo-32517: Fix failing test_asyncio on macOS 10.12.2+ due to transport of KqueueSelector loop was not being closed.

• bpo-19417: Add test_bdb.py.

Build

• bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.

Windows

• bpo-33016: Fix potential use of uninitialized memory in nt._getfinalpathname

• bpo-32903: Fix a memory leak in os.chdir() on Windows if the current directory is set to a UNC path.

macOS

• bpo-32726: Build and link with private copy of Tcl/Tk 8.6 for the macOS 10.6+ installer. The 10.9+ installer variant already does this. This means that the Python 3.7 provided by the python.org macOS installers no longer need or use any external versions of Tcl/Tk, either system-provided or user-installed, such as ActiveTcl.

IDLE

• bpo-32984: Set __file__ while running a startup file. Like Python, IDLE optionally runs one startup file in the Shell window before presenting the first interactive input prompt. For IDLE, -s runs a file named in environmental variable IDLESTARTUP or PYTHONSTARTUP; -r file runs file. Python sets __file__ to the startup file name before running the file and unsets it before the first prompt. IDLE now does the same when run normally, without the -n option.

• bpo-32940: Simplify and rename StringTranslatePseudoMapping in pyparse.

Tools/Demos

• bpo-32885: Add an -n flag for Tools/scripts/pathfix.py to disable automatic backup creation (files with ~ suffix).

C API

• bpo-33042: Embedding applications may once again call PySys_ResetWarnOptions, PySys_AddWarnOption, and PySys_AddXOption prior to calling Py_Initialize.

• bpo-32374: Document that m_traverse for multi-phase initialized modules can be called with m_state=NULL, and add a sanity check

Python 3.7.0 beta 2

Release date: 2018-02-27

Security

• bpo-28414: The ssl module now allows users to perform their own IDN en/decoding when using SNI.

Core and Builtins

• bpo-32889: Update Valgrind suppression list to account for the rename of Py_ADDRESS_IN_RANG to address_in_range.

• bpo-31356: Remove the new API added in bpo-31356 (gc.ensure_disabled() context manager).

• bpo-32305: For namespace packages, ensure that both __file__ and __spec__.origin are set to None.

• bpo-32303: Make sure __spec__.loader matches __loader__ for namespace packages.

• bpo-32711: Fix the warning messages for Python/ast_unparse.c. Patch by Stéphane Wirtel

• bpo-32583: Fix possible crashing in builtin Unicode decoders caused by write out-of-bound errors when using customized decode error handlers.

Library

• bpo-32960: For dataclasses, disallow inheriting frozen from non-frozen classes, and also disallow inheriting non-frozen from frozen classes. This restriction will be relaxed at a future date.

• bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values. Patch by Joffrey Fuhrer.

• bpo-32951: Direct instantiation of SSLSocket and SSLObject objects is now prohibited. The constructors were never documented, tested, or designed as public constructors. Users were suppose to use ssl.wrap_socket() or SSLContext.

• bpo-32929: Remove the tri-state parameter “hash”, and add the boolean “unsafe_hash”. If unsafe_hash is True, add a __hash__ function, but if a __hash__ exists, raise TypeError. If unsafe_hash is False, add a __hash__ based on the values of eq= and frozen=. The unsafe_hash=False behavior is the same as the old hash=None behavior. unsafe_hash=False is the default, just as hash=None used to be.

• bpo-32947: Add OP_ENABLE_MIDDLEBOX_COMPAT and test workaround for TLSv1.3 for future compatibility with OpenSSL 1.1.1.

• bpo-30622: The ssl module now detects missing NPN support in LibreSSL.

• bpo-32922: dbm.open() now encodes filename with the filesystem encoding rather than default encoding.

• bpo-32859: In os.dup2, don’t check every call whether the dup3 syscall exists or not.

• bpo-32556: nt._getfinalpathname, nt._getvolumepathname and nt._getdiskusage now correctly convert from bytes.

• bpo-25988: Emit a DeprecationWarning when using or importing an ABC directly from collections rather than from collections.abc.

• bpo-21060: Rewrite confusing message from setup.py upload from “No dist file created in earlier command” to the more helpful “Must create and upload files in one command”.

• bpo-32852: Make sure sys.argv remains as a list when running trace.

• bpo-31333: _abc module is added. It is a speedup module with C implementations for various functions and methods in abc. Creating an ABC subclass and calling isinstance or issubclass with an ABC subclass are up to 1.5x faster. In addition, this makes Python start-up up to 10% faster.

  Note that the new implementation hides internal registry and caches, previously accessible via private attributes _abc_registry, _abc_cache, and _abc_negative_cache. There are three debugging helper methods that can be used instead _dump_registry, _abc_registry_clear, and _abc_caches_clear.

• bpo-32841: Fixed asyncio.Condition issue which silently ignored cancellation after notifying and cancelling a conditional lock. Patch by Bar Harel.

• bpo-32819: ssl.match_hostname() has been simplified and no longer depends on re and ipaddress module for wildcard and IP addresses. Error reporting for invalid wildcards has been improved.

• bpo-32394: socket: Remove TCP_FASTOPEN,TCP_KEEPCNT,TCP_KEEPIDLE,TCP_KEEPINTVL flags on older version Windows during run-time.

• bpo-31787: Fixed refleaks of __init__() methods in various modules. (Contributed by Oren Milman)

• bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff() when only the last field is quoted. Patch by Jake Davis.

• bpo-32792: collections.ChainMap() preserves the order of the underlying mappings.

• bpo-32775: fnmatch.translate() no longer produces patterns which contain set operations. Sets starting with ‘[’ or containing ‘–’, ‘&&’, ‘~~’ or ‘||’ will be interpreted differently in regular expressions in future versions. Currently they emit warnings. fnmatch.translate() now avoids producing patterns containing such sets by accident.

• bpo-32622: Implement native fast sendfile for Windows proactor event loop.

• bpo-32777: Fix a rare but potential pre-exec child process deadlock in subprocess on POSIX systems when marking file descriptors inheritable on exec in the child process. This bug appears to have been introduced in 3.4.

• bpo-32647: The ctypes module used to depend on indirect linking for dlopen. The shared extension is now explicitly linked against libdl on platforms with dl.

• bpo-32741: Implement asyncio.TimerHandle.when() method.

• bpo-32691: Use mod_spec.parent when running modules with pdb

• bpo-32734: Fixed asyncio.Lock() safety issue which allowed acquiring and locking the same lock multiple times, without it being free. Patch by Bar Harel.

• bpo-32727: Do not include name field in SMTP envelope from address. Patch by Stéphane Wirtel

• bpo-31453: Add TLSVersion constants and SSLContext.maximum_version / minimum_version attributes. The new API wraps OpenSSL 1.1 https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_min_proto_version.html feature.

• bpo-24334: Internal implementation details of ssl module were cleaned up. The SSLSocket has one less layer of indirection. Owner and session information are now handled by the SSLSocket and SSLObject constructor. Channel binding implementation has been simplified.

• bpo-31848: Fix the error handling in Aifc_read.initfp() when the SSND chunk is not found. Patch by Zackery Spytz.

• bpo-32585: Add Ttk spinbox widget to tkinter.ttk. Patch by Alan D Moore.

• bpo-32221: Various functions returning tuple containing IPv6 addresses now omit %scope part since the same information is already encoded in scopeid tuple item. Especially this speeds up socket.recvfrom() when it receives multicast packet since useless resolving of network interface name is omitted.

• bpo-30693: The TarFile class now recurses directories in a reproducible way.

• bpo-30693: The ZipFile class now recurses directories in a reproducible way.

Documentation

• bpo-28124: The ssl module function ssl.wrap_socket() has been de-emphasized and deprecated in favor of the more secure and efficient SSLContext.wrap_socket() method.

• bpo-17232: Clarify docs for -O and -OO. Patch by Terry Reedy.

• bpo-32436: Add documentation for the contextvars module (PEP 567).

• bpo-32800: Update link to w3c doc for xml default namespaces.

• bpo-11015: Update test.support documentation.

• bpo-8722: Document __getattr__() behavior when property get() method raises AttributeError.

• bpo-32614: Modify RE examples in documentation to use raw strings to prevent DeprecationWarning and add text to REGEX HOWTO to highlight the deprecation.

• bpo-31972: Improve docstrings for pathlib.PurePath subclasses.

Tests

• bpo-31809: Add tests to verify connection with secp ECDH curves.

Build

• bpo-32898: Fix the python debug build when using COUNT_ALLOCS.

Windows

• bpo-32901: Update Tcl and Tk versions to 8.6.8

• bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

• bpo-32409: Ensures activate.bat can handle Unicode contents.

• bpo-32457: Improves handling of denormalized executable path when launching Python.

• bpo-32370: Use the correct encoding for ipconfig output in the uuid module. Patch by Segev Finer.

• bpo-29248: Fix os.readlink() on Windows, which was mistakenly treating the PrintNameOffset field of the reparse data buffer as a number of characters instead of bytes. Patch by Craig Holmquist and SSE4.

macOS

• bpo-32901: Update macOS 10.9+ installer to Tcl/Tk 8.6.8.

IDLE

• bpo-32916: Change str to code in pyparse.

• bpo-32905: Remove unused code in pyparse module.

• bpo-32874: Add tests for pyparse.

• bpo-32837: Using the system and place-dependent default encoding for open() is a bad idea for IDLE’s system and location-independent files.

• bpo-32826: Add “encoding=utf-8” to open() in IDLE’s test_help_about. GUI test test_file_buttons() only looks at initial ascii-only lines, but failed on systems where open() defaults to ‘ascii’ because readline() internally reads and decodes far enough ahead to encounter a non-ascii character in CREDITS.txt.

• bpo-32765: Update configdialog General tab docstring to add new widgets to the widget list.

Tools/Demos

• bpo-32222: Fix pygettext not extracting docstrings for functions with type annotated arguments. Patch by Toby Harradine.

Python 3.7.0 beta 1

Release date: 2018-01-30

Core and Builtins

• bpo-32703: Fix coroutine’s ResourceWarning when there’s an active error set when it’s being finalized.

• bpo-32650: Pdb and other debuggers dependent on bdb.py will correctly step over (next command) native coroutines. Patch by Pablo Galindo.

• bpo-28685: Optimize list.sort() and sorted() by using type specialized comparisons when possible.

• bpo-32685: Improve suggestion when the Python 2 form of print statement is either present on the same line as the header of a compound statement or else terminated by a semi-colon instead of a newline. Patch by Nitish Chandra.

• bpo-32697: Python now explicitly preserves the definition order of keyword-only parameters. It’s always preserved their order, but this behavior was never guaranteed before; this behavior is now guaranteed and tested.

• bpo-32690: The locals() dictionary now displays in the lexical order that variables were defined. Previously, the order was reversed.

• bpo-32677: Add .isascii() method to str, bytes and bytearray. It can be used to test that string contains only ASCII characters.

• bpo-32670: Enforce PEP 479 for all code.

  This means that manually raising a StopIteration exception from a generator is prohibited for all code, regardless of whether ‘from __future__ import generator_stop’ was used or not.

• bpo-32591: Added built-in support for tracking the origin of coroutine objects; see sys.set_coroutine_origin_tracking_depth and CoroutineType.cr_origin. This replaces the asyncio debug mode’s use of coroutine wrapping for native coroutine objects.

• bpo-31368: Expose preadv and pwritev system calls in the os module. Patch by Pablo Galindo

• bpo-32544: hasattr(obj, name) and getattr(obj, name, default) are about 4 times faster than before when name is not found and obj doesn’t override __getattr__ or __getattribute__.

• bpo-26163: Improved frozenset() hash to create more distinct hash values when faced with datasets containing many similar values.

• bpo-32550: Remove the STORE_ANNOTATION bytecode.

• bpo-20104: Expose posix_spawn as a low level API in the os module. (removed before 3.7.0rc1)

• bpo-24340: Fixed estimation of the code stack size.

• bpo-32436: Implement PEP 567 Context Variables.

• bpo-18533: repr() on a dict containing its own values() or items() no longer raises RecursionError; OrderedDict similarly. Instead, use ..., as for other recursive structures. Patch by Ben North.

• bpo-20891: Py_Initialize() now creates the GIL. The GIL is no longer created “on demand” to fix a race condition when PyGILState_Ensure() is called in a non-Python thread.

• bpo-32028: Leading whitespace is now correctly ignored when generating suggestions for converting Py2 print statements to Py3 builtin print function calls. Patch by Sanyam Khurana.

• bpo-31179: Make dict.copy() up to 5.5 times faster.

• bpo-31113: Get rid of recursion in the compiler for normal control flow.

Library

• bpo-25988: Deprecate exposing the contents of collections.abc in the regular collections module.

• bpo-31429: The default cipher suite selection of the ssl module now uses a blacklist approach rather than a hard-coded whitelist. Python no longer re-enables ciphers that have been blocked by OpenSSL security update. Default cipher suite selection can be configured on compile time.

• bpo-30306: contextlib.contextmanager now releases the arguments passed to the underlying generator as soon as the context manager is entered. Previously it would keep them alive for as long as the context manager was alive, even when not being used as a function decorator. Patch by Martin Teichmann.

• bpo-21417: Added support for setting the compression level for zipfile.ZipFile.

• bpo-32251: Implement asyncio.BufferedProtocol (provisional API).

• bpo-32513: In dataclasses, allow easier overriding of dunder methods without specifying decorator parameters.

• bpo-32660: termios makes available FIONREAD, FIONCLEX, FIOCLEX, FIOASYNC and FIONBIO also under Solaris/derivatives.

• bpo-27931: Fix email address header parsing error when the username is an empty quoted string. Patch by Xiang Zhang.

• bpo-32659: Under Solaris and derivatives, os.stat_result provides a st_fstype attribute.

• bpo-32662: Implement Server.start_serving(), Server.serve_forever(), and Server.is_serving() methods. Add ‘start_serving’ keyword parameter to loop.create_server() and loop.create_unix_server().

• bpo-32391: Implement asyncio.StreamWriter.wait_closed() and asyncio.StreamWriter.is_closing() methods

• bpo-32643: Make Task._step, Task._wakeup and Future._schedule_callbacks methods private.

• bpo-32630: Refactor decimal module to use contextvars to store decimal context.

• bpo-32622: Add asyncio.AbstractEventLoop.sendfile() method.

• bpo-32304: distutils’ upload command no longer corrupts tar files ending with a CR byte, and no longer tries to convert CR to CRLF in any of the upload text fields.

• bpo-32502: uuid.uuid1 no longer raises an exception if a 64-bit hardware address is encountered.

• bpo-32596: concurrent.futures imports ThreadPoolExecutor and ProcessPoolExecutor lazily (using PEP 562). It makes import asyncio about 15% faster because asyncio uses only ThreadPoolExecutor by default.

• bpo-31801: Add _ignore_ to Enum so temporary variables can be used during class construction without being turned into members.

• bpo-32576: Use queue.SimpleQueue() in places where it can be invoked from a weakref callback.

• bpo-32574: Fix memory leak in asyncio.Queue, when the queue has limited size and it is full, the cancelation of queue.put() can cause a memory leak. Patch by: José Melero.

• bpo-32521: The nis module is now compatible with new libnsl and headers location.

• bpo-32467: collections.abc.ValuesView now inherits from collections.abc.Collection.

• bpo-32473: Improve ABCMeta._dump_registry() output readability

• bpo-32102: New argument capture_output for subprocess.run

• bpo-32521: glibc has removed Sun RPC. Use replacement libtirpc headers and library in nis module.

• bpo-32493: UUID module fixes build for FreeBSD/OpenBSD

• bpo-32503: Pickling with protocol 4 no longer creates too small frames.

• bpo-29237: Create enum for pstats sorting options

• bpo-32454: Add close(fd) function to the socket module.

• bpo-25942: The subprocess module is now more graceful when handling a Ctrl-C KeyboardInterrupt during subprocess.call, subprocess.run, or a Popen context manager. It now waits a short amount of time for the child (presumed to have also gotten the SIGINT) to exit, before continuing the KeyboardInterrupt exception handling. This still includes a SIGKILL in the call() and run() APIs, but at least the child had a chance first.

• bpo-32433: The hmac module now has hmac.digest(), which provides an optimized HMAC digest.

• bpo-28134: Sockets now auto-detect family, type and protocol from file descriptor by default.

• bpo-32404: Fix bug where datetime.datetime.fromtimestamp() did not call __new__ in datetime.datetime subclasses.

• bpo-32403: Improved speed of datetime.date and datetime.datetime alternate constructors.

• bpo-32228: Ensure that truncate() preserves the file position (as reported by tell()) after writes longer than the buffer size.

• bpo-32410: Implement loop.sock_sendfile for asyncio event loop.

• bpo-22908: Added seek and tell to the ZipExtFile class. This only works if the file object used to open the zipfile is seekable.

• bpo-32373: Add socket.getblocking() method.

• bpo-32248: Add importlib.resources and importlib.abc.ResourceReader as the unified API for reading resources contained within packages. Loaders wishing to support resource reading must implement the get_resource_reader() method. File-based and zipimport-based loaders both implement these APIs. importlib.abc.ResourceLoader is deprecated in favor of these new APIs.

• bpo-32320: collections.namedtuple() now supports default values.

• bpo-29302: Add contextlib.AsyncExitStack. Patch by Alexander Mohr and Ilya Kulakov.

• bpo-31961: Removed in Python 3.7.0b2. The args argument of subprocess.Popen can now be a path-like object. If args is given as a sequence, it’s first element can now be a path-like object as well.

• bpo-31900: The locale.localeconv() function now sets temporarily the LC_CTYPE locale to the LC_NUMERIC locale to decode decimal_point and thousands_sep byte strings if they are non-ASCII or longer than 1 byte, and the LC_NUMERIC locale is different than the LC_CTYPE locale. This temporary change affects other threads.

  Same change for the str.format() method when formatting a number (int, float, float and subclasses) with the n type (ex: '{:n}'.format(1234)).

• bpo-31853: Use super().method instead of socket.method in SSLSocket. They were there most likely for legacy reasons.

• bpo-31399: The ssl module now uses OpenSSL’s X509_VERIFY_PARAM_set1_host() and X509_VERIFY_PARAM_set1_ip() API to verify hostname and IP addresses. Subject common name fallback can be disabled with SSLContext.hostname_checks_common_name.

• bpo-14976: Add a queue.SimpleQueue class, an unbounded FIFO queue with a reentrant C implementation of put().

Documentation

• bpo-32724: Add references to some commands in the documentation of Pdb. Patch by Stéphane Wirtel

• bpo-32649: Complete the C API documentation, profiling and tracing part with the newly added per-opcode events.

• bpo-17799: Explain real behaviour of sys.settrace and sys.setprofile and their C-API counterparts regarding which type of events are received in each function. Patch by Pablo Galindo Salgado.

Tests

• bpo-32721: Fix test_hashlib to not fail if the _md5 module is not built.

• bpo-28414: Add test cases for IDNA 2003 and 2008 host names. IDNA 2003 internationalized host names are working since bpo-31399 has landed. IDNA 2008 are still broken.

• bpo-32604: Add a new “_xxsubinterpreters” extension module that exposes the existing subinterpreter C-API and a new cross-interpreter data sharing mechanism. The module is primarily intended for more thorough testing of the existing subinterpreter support.

  Note that the _xxsubinterpreters module has been removed in 3.7.0rc1.

• bpo-32602: Add test certs and test for ECDSA cert and EC/RSA dual mode.

• bpo-32549: On Travis CI, Python now Compiles and uses a local copy of OpenSSL 1.1.0g for testing.

Build

• bpo-32635: Fix segfault of the crypt module when libxcrypt is provided instead of libcrypt at the system.

• bpo-32598: Use autoconf to detect OpenSSL libs, headers and supported features. The ax_check_openssl M4 macro uses pkg-config to locate OpenSSL and falls back to manual search.

• bpo-32593: Drop support of FreeBSD 9 and older.

• bpo-29708: If the SOURCE_DATE_EPOCH environment variable is set, py_compile will always create hash-based .pyc files.

Windows

• bpo-32588: Create standalone _distutils_findvs module and add missing _queue module to installer.

• bpo-29911: Ensure separate Modify and Uninstall buttons are displayed.

• bpo-32507: Use app-local UCRT install rather than the proper update for old versions of Windows.

macOS

• bpo-32726: Provide an additional, more modern macOS installer variant that supports macOS 10.9+ systems in 64-bit mode only. Upgrade the supplied third-party libraries to OpenSSL 1.1.0g and to SQLite 3.22.0. The 10.9+ installer now links with and supplies its own copy of Tcl/Tk 8.6.

• bpo-28440: No longer add /Library/Python/3.x/site-packages to sys.path for macOS framework builds to avoid future conflicts.

C API

• bpo-32681: Fix uninitialized variable ‘res’ in the C implementation of os.dup2. Patch by Stéphane Wirtel

• bpo-10381: Add C API access to the datetime.timezone constructor and datetime.timzone.UTC singleton.

Python 3.7.0 alpha 4

Release date: 2018-01-08

Core and Builtins

• bpo-31975: The default warning filter list now starts with a “default::DeprecationWarning:__main__” entry, so deprecation warnings are once again shown by default in single-file scripts and at the interactive prompt.

• bpo-32226: __class_getitem__ is now an automatic class method.

• bpo-32399: Add AIX uuid library support for RFC4122 using uuid_create() in libc.a

• bpo-32390: Fix the compilation failure on AIX after the f_fsid field has been added to the object returned by os.statvfs() (bpo-32143). Original patch by Michael Felt.

• bpo-32379: Make MRO computation faster when a class inherits from a single base.

• bpo-32259: The error message of a TypeError raised when unpack non-iterable is now more specific.

• bpo-27169: The __debug__ constant is now optimized out at compile time. This fixes also bpo-22091.

• bpo-32329: The -R option now turns on hash randomization when the PYTHONHASHSEED environment variable is set to 0. Previously, the option was ignored. Moreover, sys.flags.hash_randomization is now properly set to 0 when hash randomization is turned off by PYTHONHASHSEED=0.

• bpo-30416: The optimizer is now protected from spending much time doing complex calculations and consuming much memory for creating large constants in constant folding. Increased limits for constants that can be produced in constant folding.

• bpo-32282: Fix an unnecessary ifdef in the include of VersionHelpers.h in socketmodule on Windows.

• bpo-30579: Implement TracebackType.__new__ to allow Python-level creation of traceback objects, and make TracebackType.tb_next mutable.

• bpo-32260: Don’t byte swap the input keys to the SipHash algorithm on big-endian platforms. This should ensure siphash gives consistent results across platforms.

• bpo-31506: Improve the error message logic for object.__new__ and object.__init__. Patch by Sanyam Khurana.

• bpo-20361: -b and -bb now inject 'default::BytesWarning' and error::BytesWarning entries into sys.warnoptions, ensuring that they take precedence over any other warning filters configured via the -W option or the PYTHONWARNINGS environment variable.

• bpo-32230: -X dev now injects a 'default' entry into sys.warnoptions, ensuring that it behaves identically to actually passing -Wdefault at the command line.

• bpo-29240: Add a new UTF-8 mode: implementation of the PEP 540.

• bpo-32226: PEP 560: Add support for __mro_entries__ and __class_getitem__. Implemented by Ivan Levkivskyi.

• bpo-32225: PEP 562: Add support for module __getattr__ and __dir__. Implemented by Ivan Levkivskyi.

• bpo-31901: The atexit module now has its callback stored per interpreter.

• bpo-31650: Implement PEP 552 (Deterministic pycs). Python now supports invalidating bytecode cache files bashed on a source content hash rather than source last-modified time.

• bpo-29469: Move constant folding from bytecode layer to AST layer. Original patch by Eugene Toder.

Library

• bpo-32506: Now that dict is defined as keeping insertion order, drop OrderedDict and just use plain dict.

• bpo-32279: Add params to dataclasses.make_dataclasses(): init, repr, eq, order, hash, and frozen. Pass them through to dataclass().

• bpo-32278: Make type information optional on dataclasses.make_dataclass(). If omitted, the string ‘typing.Any’ is used.

• bpo-32499: Add dataclasses.is_dataclass(obj), which returns True if obj is a dataclass or an instance of one.

• bpo-32468: Improve frame repr() to mention filename, code name and current line number.

• bpo-23749: asyncio: Implement loop.start_tls()

• bpo-32441: Return the new file descriptor (i.e., the second argument) from os.dup2. Previously, None was always returned.

• bpo-32422: functools.lru_cache uses less memory (3 words for each cached key) and takes about 1/3 time for cyclic GC.

• bpo-31721: Prevent Python crash from happening when Future._log_traceback is set to True manually. Now it can only be set to False, or a ValueError is raised.

• bpo-32415: asyncio: Add Task.get_loop() and Future.get_loop()

• bpo-26133: Don’t unsubscribe signals in asyncio UNIX event loop on interpreter shutdown.

• bpo-32363: Make asyncio.Task.set_exception() and set_result() raise NotImplementedError. Task._step() and Future.__await__() raise proper exceptions when they are in an invalid state, instead of raising an AssertionError.

• bpo-32357: Optimize asyncio.iscoroutine() and loop.create_task() for non-native coroutines (e.g. async/await compiled with Cython).

  ‘loop.create_task(python_coroutine)’ used to be 20% faster than ‘loop.create_task(cython_coroutine)’. Now, the latter is as fast.

• bpo-32356: asyncio.transport.resume_reading() and pause_reading() are now idempotent. New transport.is_reading() method is added.

• bpo-32355: Optimize asyncio.gather(); now up to 15% faster.

• bpo-32351: Use fastpath in asyncio.sleep if delay<0 (2x boost)

• bpo-32348: Optimize asyncio.Future schedule/add/remove callback. The optimization shows 3-6% performance improvements of async/await code.

• bpo-32331: Fix socket.settimeout() and socket.setblocking() to keep socket.type as is. Fix socket.socket() constructor to reset any bit flags applied to socket’s type. This change only affects OSes that have SOCK_NONBLOCK and/or SOCK_CLOEXEC.

• bpo-32248: Add importlib.abc.ResourceReader as an ABC for loaders to provide a unified API for reading resources contained within packages. Also add importlib.resources as the port of importlib_resources.

• bpo-32311: Implement asyncio.create_task(coro) shortcut

• bpo-32327: Convert asyncio functions that were documented as coroutines to coroutines. Affected functions: loop.sock_sendall, loop.sock_recv, loop.sock_accept, loop.getaddrinfo, loop.getnameinfo.

• bpo-32323: urllib.parse.urlsplit() does not convert zone-id (scope) to lower case for scoped IPv6 addresses in hostnames now.

• bpo-32302: Fix bdist_wininst of distutils for CRT v142: it binary compatible with CRT v140.

• bpo-29711: Fix stop_serving in asyncio proactor loop kill all listening servers

• bpo-32308: re.sub() now replaces empty matches adjacent to a previous non-empty match.

• bpo-29970: Abort asyncio SSLProtocol connection if handshake not complete within 10s

• bpo-32314: Implement asyncio.run().

• bpo-17852: Revert incorrect fix based on misunderstanding of _Py_PyAtExit() semantics.

• bpo-32296: Implement asyncio._get_running_loop() and get_event_loop() in C. This makes them 4x faster.

• bpo-32250: Implement asyncio.current_task() and asyncio.all_tasks(). Add helpers intended to be used by alternative task implementations: asyncio._register_task, asyncio._enter_task, asyncio._leave_task and asyncio._unregister_task. Deprecate asyncio.Task.current_task() and asyncio.Task.all_tasks().

• bpo-32255: A single empty field is now always quoted when written into a CSV file. This allows to distinguish an empty row from a row consisting of a single empty field. Patch by Licht Takeuchi.

• bpo-32277: Raise NotImplementedError instead of SystemError on platforms where chmod(..., follow_symlinks=False) is not supported. Patch by Anthony Sottile.

• bpo-30050: New argument warn_on_full_buffer to signal.set_wakeup_fd lets you control whether Python prints a warning on stderr when the wakeup fd buffer overflows.

• bpo-29137: The fpectl library has been removed. It was never enabled by default, never worked correctly on x86-64, and it changed the Python ABI in ways that caused unexpected breakage of C extensions.

• bpo-32273: Move asyncio.test_utils to test.test_asyncio.

• bpo-32272: Remove asyncio.async() function.

• bpo-32269: Add asyncio.get_running_loop() function.

• bpo-32265: All class and static methods of builtin types now are correctly classified by inspect.classify_class_attrs() and grouped in pydoc ouput. Added types.ClassMethodDescriptorType for unbound class methods of builtin types.

• bpo-32253: Deprecate yield from lock, await lock, with (yield from lock) and with await lock for asyncio synchronization primitives.

• bpo-22589: Changed MIME type of .bmp from ‘image/x-ms-bmp’ to ‘image/bmp’

• bpo-32193: Convert asyncio to use async/await syntax. Old styled yield from is still supported too.

• bpo-32206: Add support to run modules with pdb

• bpo-32227: functools.singledispatch now supports registering implementations using type annotations.

• bpo-15873: Added new alternate constructors datetime.datetime.fromisoformat(), datetime.time.fromisoformat() and datetime.date.fromisoformat() as the inverse operation of each classes’s respective isoformat methods.

• bpo-32199: The getnode() ip getter now uses ‘ip link’ instead of ‘ip link list’.

• bpo-32143: os.statvfs() includes the f_fsid field from statvfs(2)

• bpo-26439: Fix ctypes.util.find_library() for AIX by implementing ctypes._aix.find_library() Patch by: Michael Felt

• bpo-31993: The pickler now uses less memory when serializing large bytes and str objects into a file. Pickles created with protocol 4 will require less memory for unpickling large bytes and str objects.

• bpo-27456: Ensure TCP_NODELAY is set on Linux. Tests by Victor Stinner.

• bpo-31778: ast.literal_eval() is now more strict. Addition and subtraction of arbitrary numbers no longer allowed.

• bpo-31802: Importing native path module (posixpath, ntpath) now works even if the os module still is not imported.

• bpo-30241: Add contextlib.AbstractAsyncContextManager. Patch by Jelle Zijlstra.

• bpo-31699: Fix deadlocks in concurrent.futures.ProcessPoolExecutor when task arguments or results cause pickling or unpickling errors. This should make sure that calls to the ProcessPoolExecutor API always eventually return.

• bpo-15216: TextIOWrapper.reconfigure() supports changing encoding, errors, and newline.

Documentation

• bpo-32418: Add get_loop() method to Server and AbstractServer classes.

Tests

• bpo-32252: Fix faulthandler_suppress_crash_report() used to prevent core dump files when testing crashes. getrlimit() returns zero on success.

• bpo-32002: Adjust C locale coercion testing for the empty locale and POSIX locale cases to more readily adjust to platform dependent behaviour.

Windows

• bpo-19764: Implement support for subprocess.Popen(close_fds=True) on Windows. Patch by Segev Finer.

Tools/Demos

• bpo-24960: 2to3 and lib2to3 can now read pickled grammar files using pkgutil.get_data() rather than probing the filesystem. This lets 2to3 and lib2to3 work when run from a zipfile.

C API

• bpo-32030: Py_Initialize() doesn’t reset the memory allocators to default if the PYTHONMALLOC environment variable is not set.

• bpo-29084: Undocumented C API for OrderedDict has been excluded from the limited C API. It was added by mistake and actually never worked in the limited C API.

• bpo-32264: Moved the pygetopt.h header into internal/, since it has no public APIs.

• bpo-32241: Py_SetProgramName() and Py_SetPythonHome() now take the const wchar * arguments instead of wchar *.

Python 3.7.0 alpha 3

Release date: 2017-12-05

Core and Builtins

• bpo-32176: co_flags.CO_NOFREE is now always set correctly by the code object constructor based on freevars and cellvars, rather than needing to be set correctly by the caller. This ensures it will be cleared automatically when additional cell references are injected into a modified code object and function.

• bpo-10544: Yield expressions are now deprecated in comprehensions and generator expressions. They are still permitted in the definition of the outermost iterable, as that is evaluated directly in the enclosing scope.

• bpo-32137: The repr of deeply nested dict now raises a RecursionError instead of crashing due to a stack overflow.

• bpo-32096: Revert memory allocator changes in the C API: move structures back from _PyRuntime to Objects/obmalloc.c. The memory allocators are once again initialized statically, and so PyMem_RawMalloc() and Py_DecodeLocale() can be called before _PyRuntime_Initialize().

• bpo-32043: Add a new “developer mode”: new “-X dev” command line option to enable debug checks at runtime.

• bpo-32023: SyntaxError is now correctly raised when a generator expression without parenthesis is used instead of an inheritance list in a class definition. The duplication of the parentheses can be omitted only on calls.

• bpo-32012: SyntaxError is now correctly raised when a generator expression without parenthesis is passed as an argument, but followed by a trailing comma. A generator expression always needs to be directly inside a set of parentheses and cannot have a comma on either side.

• bpo-28180: A new internal _Py_SetLocaleFromEnv(category) helper function has been added in order to improve the consistency of behaviour across different libc implementations (e.g. Android doesn’t support setting the locale from the environment by default).

• bpo-31949: Fixed several issues in printing tracebacks (PyTraceBack_Print()).

  • Setting sys.tracebacklimit to 0 or less now suppresses printing tracebacks.

  • Setting sys.tracebacklimit to None now causes using the default limit.

  • Setting sys.tracebacklimit to an integer larger than LONG_MAX now means using the limit LONG_MAX rather than the default limit.

  • Fixed integer overflows in the case of more than 2**31 traceback items on Windows.

  • Fixed output errors handling.

• bpo-30696: Fix the interactive interpreter looping endlessly when no memory.

• bpo-20047: Bytearray methods partition() and rpartition() now accept only bytes-like objects as separator, as documented. In particular they now raise TypeError rather of returning a bogus result when an integer is passed as a separator.

• bpo-21720: BytesWarning no longer emitted when the fromlist argument of __import__() or the __all__ attribute of the module contain bytes instances.

• bpo-31845: Environment variables are once more read correctly at interpreter startup.

• bpo-28936: Ensure that lexically first syntax error involving a parameter and global or nonlocal is detected first at a given scope. Patch by Ivan Levkivskyi.

• bpo-31825: Fixed OverflowError in the ‘unicode-escape’ codec and in codecs.escape_decode() when decode an escaped non-ascii byte.

• bpo-31618: The per-frame tracing logic added in 3.7a1 has been altered so that frame->f_lineno is updated before either "line" or "opcode" events are emitted. Previously, opcode events were emitted first, and therefore would occasionally see stale line numbers on the frame. The behavior of this feature has changed slightly as a result: when both f_trace_lines and f_trace_opcodes are enabled, line events now occur first.

• bpo-28603: Print the full context/cause chain of exceptions on interpreter exit, even if an exception in the chain is unhashable or compares equal to later ones. Patch by Zane Bitter.

• bpo-31786: Fix timeout rounding in the select module to round correctly negative timeouts between -1.0 and 0.0. The functions now block waiting for events as expected. Previously, the call was incorrectly non-blocking. Patch by Pablo Galindo.

• bpo-31781: Prevent crashes when calling methods of an uninitialized zipimport.zipimporter object. Patch by Oren Milman.

• bpo-30399: Standard repr() of BaseException with a single argument no longer contains redundant trailing comma.

• bpo-31626: Fixed a bug in debug memory allocator. There was a write to freed memory after shrinking a memory block.

• bpo-30817: PyErr_PrintEx() clears now the ignored exception that may be raised by _PySys_SetObjectId(), for example when no memory.

Library

• bpo-28556: Two minor fixes for typing module: allow shallow copying instances of generic classes, improve interaction of __init_subclass__ with generics. Original PRs by Ivan Levkivskyi.

• bpo-32214: PEP 557, Data Classes. Provides a decorator which adds boilerplate methods to classes which use type annotations so specify fields.

• bpo-27240: The header folding algorithm for the new email policies has been rewritten, which also fixes bpo-30788, bpo-31831, and bpo-32182. In particular, RFC2231 folding is now done correctly.

• bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the GIL when getting the file size. Fixed hang of all threads with inaccessible NFS server. Patch by Nir Soffer.

• bpo-32101: Add sys.flags.dev_mode flag

• bpo-32154: The asyncio.windows_utils.socketpair() function has been removed: use directly socket.socketpair() which is available on all platforms since Python 3.5 (before, it wasn’t available on Windows). asyncio.windows_utils.socketpair() was just an alias to socket.socketpair on Python 3.5 and newer.

• bpo-32089: warnings: In development (-X dev) and debug mode (pydebug build), use the “default” action for ResourceWarning, rather than the “always” action, in the default warnings filters.

• bpo-32107: uuid.getnode() now preferentially returns universally administered MAC addresses if available, over locally administered MAC addresses. This makes a better guarantee for global uniqueness of UUIDs returned from uuid.uuid1(). If only locally administered MAC addresses are available, the first such one found is returned.

• bpo-23033: Wildcard is now supported in hostname when it is one and only character in the left most segment of hostname in second argument of ssl.match_hostname(). Patch by Mandeep Singh.

• bpo-12239: Make msilib.SummaryInformation.GetProperty() return None when the value of property is VT_EMPTY. Initial patch by Mark Mc Mahon.

• bpo-28334: Use os.path.expanduser() to find the ~/.netrc file in netrc.netrc. If it does not exist, FileNotFoundError is raised. Patch by Dimitri Merejkowsky.

• bpo-32121: Made tracemalloc.Traceback behave more like the traceback module, sorting the frames from oldest to most recent. Traceback.format() now accepts negative limit, truncating the result to the abs(limit) oldest frames. To get the old behaviour, one can use the new most_recent_first argument to Traceback.format(). (Patch by Jesse Bakker.)

• bpo-31325: Fix wrong usage of collections.namedtuple() in the RobotFileParser.parse() method.

  Initial patch by Robin Wellner.

• bpo-12382: msilib.OpenDatabase() now raises a better exception message when it couldn’t open or create an MSI file. Initial patch by William Tisäter.

• bpo-19610: setup() now warns about invalid types for some fields.

  The distutils.dist.Distribution class now warns when classifiers, keywords and platforms fields are not specified as a list or a string.

• bpo-32071: Added the -k command-line option to python -m unittest to run only tests that match the given pattern(s).

• bpo-10049: Added nullcontext no-op context manager to contextlib. This provides a simpler and faster alternative to ExitStack() when handling optional context managers.

• bpo-28684: The new test.support.skip_unless_bind_unix_socket() decorator is used here to skip asyncio tests that fail because the platform lacks a functional bind() function for unix domain sockets (as it is the case for non root users on the recent Android versions that run now SELinux in enforcing mode).

• bpo-32110: codecs.StreamReader.read(n) now returns not more than n characters/bytes for non-negative n. This makes it compatible with read() methods of other file-like objects.

• bpo-27535: The warnings module doesn’t leak memory anymore in the hidden warnings registry for the “ignore” action of warnings filters. warn_explicit() function doesn’t add the warning key to the registry anymore for the “ignore” action.

• bpo-32088: warnings: When Python is build is debug mode (Py_DEBUG), DeprecationWarning, PendingDeprecationWarning and ImportWarning warnings are now displayed by default.

• bpo-1647489: Fixed searching regular expression patterns that could match an empty string. Non-empty string can now be correctly found after matching an empty string.

• bpo-25054: Added support of splitting on a pattern that could match an empty string.

• bpo-32072: Fixed issues with binary plists:

  • Fixed saving bytearrays.

  • Identical objects will be saved only once.

  • Equal references will be load as identical objects.

  • Added support for saving and loading recursive data structures.

• bpo-32069: Drop legacy SSL transport from asyncio, ssl.MemoryBIO is always used anyway.

• bpo-32066: asyncio: Support pathlib.Path in create_unix_connection; sock arg should be optional

• bpo-32046: Updates 2to3 to convert from operator.isCallable(obj) to callable(obj). Patch by Dong-hee Na.

• bpo-32018: inspect.signature should follow PEP 8, if the parameter has an annotation and a default value. Patch by Dong-hee Na.

• bpo-32025: Add time.thread_time() and time.thread_time_ns()

• bpo-32037: Integers that fit in a signed 32-bit integer will be now pickled with protocol 0 using the INT opcode. This will decrease the size of a pickle, speed up pickling and unpickling, and make these integers be unpickled as int instances in Python 2.

• bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunError pickleable.

• bpo-32015: Fixed the looping of asyncio in the case of reconnection the socket during waiting async read/write from/to the socket.

• bpo-32011: Restored support of loading marshal files with the TYPE_INT64 code. These files can be produced in Python 2.7.

• bpo-28369: Enhance add_reader/writer check that socket is not used by some transport. Before, only cases when add_reader/writer were called with an int FD were supported. Now the check is implemented correctly for all file-like objects.

• bpo-31976: Fix race condition when flushing a file is slow, which can cause a segfault if closing the file from another thread.

• bpo-31985: Formally deprecated aifc.openfp, sunau.openfp, and wave.openfp. Since change 7bc817d5ba917528e8bd07ec461c635291e7b06a in 1993, openfp in each of the three modules had been pointing to that module’s open function as a matter of backwards compatibility, though it had been both untested and undocumented.

• bpo-21862: cProfile command line now accepts -m module_name as an alternative to script path. Patch by Sanyam Khurana.

• bpo-31970: Reduce performance overhead of asyncio debug mode.

• bpo-31843: database argument of sqlite3.connect() now accepts a path-like object, instead of just a string.

• bpo-31945: Add Configurable blocksize to HTTPConnection and HTTPSConnection for improved upload throughput. Patch by Nir Soffer.

• bpo-31943: Add a cancelled() method to asyncio.Handle. Patch by Marat Sharafutdinov.

• bpo-9678: Fixed determining the MAC address in the uuid module:

  • Using ifconfig on NetBSD and OpenBSD.

  • Using arp on Linux, FreeBSD, NetBSD and OpenBSD.

  Based on patch by Takayuki Shimizukawa.

• bpo-30057: Fix potential missed signal in signal.signal().

• bpo-31933: Fix Blake2 params leaf_size and node_offset on big endian platforms. Patch by Jack O’Connor.

• bpo-21423: Add an initializer argument to {Process,Thread}PoolExecutor

• bpo-31927: Fixed compilation of the socket module on NetBSD 8. Fixed assertion failure or reading arbitrary data when parse a AF_BLUETOOTH address on NetBSD and DragonFly BSD.

• bpo-27666: Fixed stack corruption in curses.box() and curses.ungetmouse() when the size of types chtype or mmask_t is less than the size of C long. curses.box() now accepts characters as arguments. Based on patch by Steve Fink.

• bpo-31917: Add 3 new clock identifiers: time.CLOCK_BOOTTIME, time.CLOCK_PROF and time.CLOCK_UPTIME.

• bpo-31897: plistlib now catches more errors when read binary plists and raises InvalidFileException instead of unexpected exceptions.

• bpo-25720: Fix the method for checking pad state of curses WINDOW. Patch by Masayuki Yamamoto.

• bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD and NetBSD. Fixed the comparison of the kqueue_event objects.

• bpo-31891: Fixed building the curses module on NetBSD.

• bpo-31884: added required constants to subprocess module for setting priority on windows

• bpo-28281: Remove year (1-9999) limits on the Calendar.weekday() function.

  Patch by Mark Gollahon.

• bpo-31702: crypt.mksalt() now allows to specify the number of rounds for SHA-256 and SHA-512 hashing.

• bpo-30639: inspect.getfile() no longer computes the repr of unknown objects to display in an error message, to protect against badly behaved custom reprs.

• bpo-30768: Fix the pthread+semaphore implementation of PyThread_acquire_lock_timed() when called with timeout > 0 and intr_flag=0: recompute the timeout if sem_timedwait() is interrupted by a signal (EINTR). See also the PEP 475.

• bpo-31854: Add mmap.ACCESS_DEFAULT constant.

• bpo-31834: Use optimized code for BLAKE2 only with SSSE3+. The pure SSE2 implementation is slower than the pure C reference implementation.

• bpo-28292: Calendar.itermonthdates() will now consistently raise an exception when a date falls outside of the 0001-01-01 through 9999-12-31 range. To support applications that cannot tolerate such exceptions, the new methods itermonthdays3() and itermonthdays4() are added. The new methods return tuples and are not restricted by the range supported by datetime.date.

• bpo-28564: The shutil.rmtree() function has been sped up to 20–40%. This was done using the os.scandir() function.

• bpo-28416: Instances of pickle.Pickler subclass with the persistent_id() method and pickle.Unpickler subclass with the persistent_load() method no longer create reference cycles.

• bpo-31653: Don’t release the GIL if we can acquire a multiprocessing semaphore immediately.

• bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is closed or None.

• bpo-20825: Add subnet_of and superset_of containment tests to ipaddress.IPv6Network and ipaddress.IPv4Network. Patch by Michel Albert and Cheryl Sabella.

• bpo-31827: Remove the os.stat_float_times() function. It was introduced in Python 2.3 for backward compatibility with Python 2.2, and was deprecated since Python 3.1.

• bpo-31756: Add a subprocess.Popen(text=False) keyword argument to subprocess functions to be more explicit about when the library should attempt to decode outputs into text. Patch by Andrew Clegg.

• bpo-31819: Add AbstractEventLoop.sock_recv_into().

• bpo-31457: If nested log adapters are used, the inner process() methods are no longer omitted.

• bpo-31457: The manager property on LoggerAdapter objects is now properly settable.

• bpo-31806: Fix timeout rounding in time.sleep(), threading.Lock.acquire() and socket.socket.settimeout() to round correctly negative timeouts between -1.0 and 0.0. The functions now block waiting for events as expected. Previously, the call was incorrectly non-blocking. Patch by Pablo Galindo.

• bpo-31803: time.clock() and time.get_clock_info(‘clock’) now emit a DeprecationWarning warning.

• bpo-31800: Extended support for parsing UTC offsets. strptime ‘%z’ can now parse the output generated by datetime.isoformat, including seconds and microseconds.

• bpo-28603: traceback: Fix a TypeError that occurred during printing of exception tracebacks when either the current exception or an exception in its context/cause chain is unhashable. Patch by Zane Bitter.

• bpo-30541: Add new function to seal a mock and prevent the automatically creation of child mocks. Patch by Mario Corchero.

• bpo-31784: Implement the PEP 564, add new 6 new functions with nanosecond resolution to the time module: clock_gettime_ns(), clock_settime_ns(), monotonic_ns(), perf_counter_ns(), process_time_ns(), time_ns().

• bpo-30143: 2to3 now generates a code that uses abstract collection classes from collections.abc rather than collections.

• bpo-31770: Prevent a crash when calling the __init__() method of a sqlite3.Cursor object more than once. Patch by Oren Milman.

• bpo-31764: Prevent a crash in sqlite3.Cursor.close() in case the Cursor object is uninitialized. Patch by Oren Milman.

• bpo-31752: Fix possible crash in timedelta constructor called with custom integers.

• bpo-31620: an empty asyncio.Queue now doesn’t leak memory when queue.get pollers timeout

• bpo-31690: Allow the flags re.ASCII, re.LOCALE, and re.UNICODE to be used as group flags for regular expressions.

• bpo-30349: FutureWarning is now emitted if a regular expression contains character set constructs that will change semantically in the future (nested sets and set operations).

• bpo-31664: Added support for the Blowfish hashing in the crypt module.

• bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport in asyncio module. This method was previously modifying a wrong reference to the protocol.

• bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7 and earlier.

• bpo-31307: Allow use of bytes objects for arguments to configparser.ConfigParser.read(). Patch by Vincent Michel.

• bpo-31334: Fix poll.poll([timeout]) in the select module for arbitrary negative timeouts on all OSes where it can only be a non-negative integer or -1. Patch by Riccardo Coccioli.

• bpo-31310: multiprocessing’s semaphore tracker should be launched again if crashed.

• bpo-31308: Make multiprocessing’s forkserver process immune to Ctrl-C and other user interruptions. If it crashes, restart it when necessary.

• bpo-31245: Added support for AF_UNIX socket in asyncio create_datagram_endpoint.

• bpo-30553: Add HTTP/2 status code 421 (Misdirected Request) to http.HTTPStatus. Patch by Vitor Pereira.

Documentation

• bpo-32105: Added asyncio.BaseEventLoop.connect_accepted_socket versionadded marker.

Tests

• bpo-31380: Skip test_httpservers test_undecodable_file on macOS: fails on APFS.

• bpo-31705: Skip test_socket.test_sha256() on Linux kernel older than 4.5. The test fails with ENOKEY on kernel 3.10 (on ppc64le). A fix was merged into the kernel 4.5.

• bpo-32138: Skip on Android test_faulthandler tests that raise SIGSEGV and remove the test.support.requires_android_level decorator.

• bpo-32136: The runtime embedding tests have been split out from Lib/test/test_capi.py into a new Lib/test/test_embed.py file.

• bpo-28668: test.support.requires_multiprocessing_queue is removed. Skip tests with test.support.import_module(‘multiprocessing.synchronize’) instead when the semaphore implementation is broken or missing.

• bpo-32126: Skip test_get_event_loop_new_process in test.test_asyncio.test_events when sem_open() is not functional.

• bpo-31174: Fix test_tools.test_unparse: DirectoryTestCase now stores the names sample to always test the same files. It prevents false alarms when hunting reference leaks.

Build

• bpo-28538: Revert the previous changes, the if_nameindex structure is defined by Unified Headers.

• bpo-28762: Revert the last commit, the F_LOCK macro is defined by Android Unified Headers.

• bpo-29040: Support building Android with Unified Headers. The first NDK release to support Unified Headers is android-ndk-r14.

• bpo-32059: detect_modules() in setup.py now also searches the sysroot paths when cross-compiling.

• bpo-31957: Fixes Windows SDK version detection when building for Windows.

• bpo-31609: Fixes quotes in PCbuild/clean.bat

• bpo-31934: Abort the build when building out of a not clean source tree.

• bpo-31926: Fixed Argument Clinic sometimes causing compilation errors when there was more than one function and/or method in a .c file with the same name.

• bpo-28791: Update Windows builds to use SQLite 3.21.0.

• bpo-28791: Update OS X installer to use SQLite 3.21.0.

• bpo-28643: Record profile-opt build progress with stamp files.

• bpo-31866: Finish removing support for AtheOS.

Windows

• bpo-1102: Return None when View.Fetch() returns ERROR_NO_MORE_ITEMS instead of raising MSIError.

  Initial patch by Anthony Tuininga.

• bpo-31944: Fixes Modify button in Apps and Features dialog.

• bpo-20486: Implement the Database.Close() method to help closing MSI database objects.

• bpo-31857: Make the behavior of USE_STACKCHECK deterministic in a multi-threaded environment.

macOS

• bpo-31392: Update macOS installer to use OpenSSL 1.0.2m

IDLE

• bpo-32207: Improve tk event exception tracebacks in IDLE. When tk event handling is driven by IDLE’s run loop, a confusing and distracting queue.EMPTY traceback context is no longer added to tk event exception tracebacks. The traceback is now the same as when event handling is driven by user code. Patch based on a suggestion by Serhiy Storchaka.

• bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of TabbedPageSet in configdialog was replaced by ttk.Notebook.

• bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests. Patch mostly by Cheryl Sabella.

• bpo-31858: IDLE – Restrict shell prompt manipulation to the shell. Editor and output windows only see an empty last prompt line. This simplifies the code and fixes a minor bug when newline is inserted. Sys.ps1, if present, is read on Shell start-up, but is not set or changed.

• bpo-31860: The font sample in the IDLE configuration dialog is now editable. Changes persist while IDLE remains open

• bpo-31836: Test_code_module now passes if run after test_idle, which sets ps1.

  The code module uses sys.ps1 if present or sets it to ‘>>> ‘ if not. Test_code_module now properly tests both behaviors. Ditto for ps2.

• bpo-28603: Fix a TypeError that caused a shell restart when printing a traceback that includes an exception that is unhashable. Patch by Zane Bitter.

• bpo-13802: Use non-Latin characters in the IDLE’s Font settings sample. Even if one selects a font that defines a limited subset of the unicode Basic Multilingual Plane, tcl/tk will use other fonts that define a character. The expanded example give users of non-Latin characters a better idea of what they might see in IDLE’s shell and editors.

  To make room for the expanded sample, frames on the Font tab are re-arranged. The Font/Tabs help explains a bit about the additions.

Tools/Demos

• bpo-32159: Remove CVS and Subversion tools: remove svneol.py and treesync.py scripts. CPython migrated from CVS to Subversion, to Mercurial, and then to Git. CVS and Subversion are no longer used to develop CPython.

• bpo-30722: Make redemo work with Python 3.6 and newer versions.

  Also, remove the LOCALE option since it doesn’t work with string patterns in Python 3.

  Patch by Christoph Sarnowski.

C API

• bpo-20891: Fix PyGILState_Ensure(). When PyGILState_Ensure() is called in a non-Python thread before PyEval_InitThreads(), only call PyEval_InitThreads() after calling PyThreadState_New() to fix a crash.

• bpo-32125: The Py_UseClassExceptionsFlag flag has been removed. It was deprecated and wasn’t used anymore since Python 2.0.

• bpo-25612: Move the current exception state from the frame object to the co-routine. This simplifies the interpreter and fixes a couple of obscure bugs caused by having swap exception state when entering or exiting a generator.

• bpo-23699: Add Py_RETURN_RICHCOMPARE macro to reduce boilerplate code in rich comparison functions.

• bpo-30697: The PyExc_RecursionErrorInst singleton is removed and PyErr_NormalizeException() does not use it anymore. This singleton is persistent and its members being never cleared may cause a segfault during finalization of the interpreter. See also bpo-22898.

Python 3.7.0 alpha 2

Release date: 2017-10-16

Core and Builtins

• bpo-31558: gc.freeze() is a new API that allows for moving all objects currently tracked by the garbage collector to a permanent generation, effectively removing them from future collection events. This can be used to protect those objects from having their PyGC_Head mutated. In effect, this enables great copy-on-write stability at fork().

• bpo-31642: Restored blocking “from package import module” by setting sys.modules[“package.module”] to None.

• bpo-31708: Allow use of asynchronous generator expressions in synchronous functions.

• bpo-31709: Drop support of asynchronous __aiter__.

• bpo-30404: The -u option now makes the stdout and stderr streams unbuffered rather than line-buffered.

• bpo-31619: Fixed a ValueError when convert a string with large number of underscores to integer with binary base.

• bpo-31602: Fix an assertion failure in zipimporter.get_source() in case of a bad zlib.decompress(). Patch by Oren Milman.

• bpo-31592: Fixed an assertion failure in Python parser in case of a bad unicodedata.normalize(). Patch by Oren Milman.

• bpo-31588: Raise a TypeError with a helpful error message when class creation fails due to a metaclass with a bad __prepare__() method. Patch by Oren Milman.

• bpo-31574: Importlib was instrumented with two dtrace probes to profile import timing.

• bpo-31566: Fix an assertion failure in _warnings.warn() in case of a bad __name__ global. Patch by Oren Milman.

• bpo-31506: Improved the error message logic for object.__new__ and object.__init__.

• bpo-31505: Fix an assertion failure in json, in case _json.make_encoder() received a bad encoder() argument. Patch by Oren Milman.

• bpo-31492: Fix assertion failures in case of failing to import from a module with a bad __name__ attribute, and in case of failing to access an attribute of such a module. Patch by Oren Milman.

• bpo-31478: Fix an assertion failure in _random.Random.seed() in case the argument has a bad __abs__() method. Patch by Oren Milman.

• bpo-31336: Speed up class creation by 10-20% by reducing the overhead in the necessary special method lookups. Patch by Stefan Behnel.

• bpo-31415: Add -X importtime option to show how long each import takes. It can be used to optimize application’s startup time. Support the PYTHONPROFILEIMPORTTIME as an equivalent way to enable this.

• bpo-31410: Optimized calling wrapper and classmethod descriptors.

• bpo-31353: PEP 553 - Add a new built-in called breakpoint() which calls sys.breakpointhook(). By default this imports pdb and calls pdb.set_trace(), but users may override sys.breakpointhook() to call whatever debugger they want. The original value of the hook is saved in sys.__breakpointhook__.

• bpo-17852: Maintain a list of open buffered files, flush them before exiting the interpreter. Based on a patch from Armin Rigo.

• bpo-31315: Fix an assertion failure in imp.create_dynamic(), when spec.name is not a string. Patch by Oren Milman.

• bpo-31311: Fix a crash in the __setstate__() method of ctypes._CData, in case of a bad __dict__. Patch by Oren Milman.

• bpo-31293: Fix crashes in true division and multiplication of a timedelta object by a float with a bad as_integer_ratio() method. Patch by Oren Milman.

• bpo-31285: Fix an assertion failure in warnings.warn_explicit, when the return value of the received loader’s get_source() has a bad splitlines() method. Patch by Oren Milman.

• bpo-30406: Make async and await proper keywords, as specified in PEP 492.

Library

• bpo-30058: Fixed buffer overflow in select.kqueue.control().

• bpo-31672: idpattern in string.Template matched some non-ASCII characters. Now it uses -i regular expression local flag to avoid non-ASCII characters.

• bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COM exceptions.

• bpo-31728: Prevent crashes in _elementtree due to unsafe cleanup of Element.text and Element.tail. Patch by Oren Milman.

• bpo-31671: Now re.compile() converts passed RegexFlag to normal int object before compiling. bm_regex_compile benchmark shows 14% performance improvements.

• bpo-30397: The types of compiled regular objects and match objects are now exposed as re.Pattern and re.Match. This adds information in pydoc output for the re module.

• bpo-31675: Fixed memory leaks in Tkinter’s methods splitlist() and split() when pass a string larger than 2 GiB.

• bpo-31673: Fixed typo in the name of Tkinter’s method adderrorinfo().

• bpo-31648: Improvements to path predicates in ElementTree:

  • Allow whitespace around predicate parts, i.e. “[a = ‘text’]” instead of requiring the less readable “[a=’text’]”.

  • Add support for text comparison of the current node, like “[.=’text’]”.

  Patch by Stefan Behnel.

• bpo-30806: Fix the string representation of a netrc object.

• bpo-31638: Add optional argument compressed to zipapp.create_archive, and add option --compress to the command line interface of zipapp.

• bpo-25351: Avoid venv activate failures with undefined variables

• bpo-20519: Avoid ctypes use (if possible) and improve import time for uuid.

• bpo-28293: The regular expression cache is no longer completely dumped when it is full.

• bpo-31596: Added pthread_getcpuclockid() to the time module

• bpo-27494: Make 2to3 accept a trailing comma in generator expressions. For example, set(x for x in [],) is now allowed.

• bpo-30347: Stop crashes when concurrently iterate over itertools.groupby() iterators.

• bpo-30346: An iterator produced by itertools.groupby() iterator now becomes exhausted after advancing the groupby iterator.

• bpo-31556: Cancel asyncio.wait_for future faster if timeout <= 0

• bpo-31540: Allow passing a context object in concurrent.futures.ProcessPoolExecutor constructor. Also, free job resources in concurrent.futures.ProcessPoolExecutor earlier to improve memory usage when a worker waits for new jobs.

• bpo-31516: threading.current_thread() should not return a dummy thread at shutdown.

• bpo-31525: In the sqlite module, require the sqlite3_prepare_v2 API. Thus, the sqlite module now requires sqlite version at least 3.3.9.

• bpo-26510: argparse subparsers are now required by default. This matches behaviour in Python 2. For optional subparsers, use the new parameter add_subparsers(required=False). Patch by Anthony Sottile. (As of 3.7.0rc1, the default was changed to not required as had been the case since Python 3.3.)

• bpo-27541: Reprs of subclasses of some collection and iterator classes (bytearray, array.array, collections.deque, collections.defaultdict, itertools.count, itertools.repeat) now contain actual type name insteads of hardcoded name of the base class.

• bpo-31351: python -m ensurepip now exits with non-zero exit code if pip bootstrapping has failed.

• bpo-31389: pdb.set_trace() now takes an optional keyword-only argument header. If given, this is printed to the console just before debugging begins.

Documentation

• bpo-31537: Fix incorrect usage of get_history_length in readline documentation example code. Patch by Brad Smith.

• bpo-30085: The operator functions without double underscores are preferred for clarity. The one with underscores are only kept for back-compatibility.

Build

• bpo-31696: Improve compiler version information in sys.version when Python is built with Clang.

• bpo-31625: Stop using ranlib on static libraries. Instead, we assume ar supports the ‘s’ flag.

• bpo-31624: Remove support for BSD/OS.

• bpo-22140: Prevent double substitution of prefix in python-config.sh.

• bpo-31569: Correct PCBuild/ case to PCbuild/ in build scripts and documentation.

• bpo-31536: Avoid wholesale rebuild after make regen-all if nothing changed.

IDLE

• bpo-31460: Simplify the API of IDLE’s Module Browser.

  Passing a widget instead of an flist with a root widget opens the option of creating a browser frame that is only part of a window. Passing a full file name instead of pieces assumed to come from a .py file opens the possibility of browsing python files that do not end in .py.

• bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

• bpo-31559: Remove test order dependence in idle_test.test_browser.

• bpo-31459: Rename IDLE’s module browser from Class Browser to Module Browser. The original module-level class and method browser became a module browser, with the addition of module-level functions, years ago. Nested classes and functions were added yesterday. For back-compatibility, the virtual event <<open-class-browser>>, which appears on the Keys tab of the Settings dialog, is not changed. Patch by Cheryl Sabella.

• bpo-31500: Default fonts now are scaled on HiDPI displays.

• bpo-1612262: IDLE module browser now shows nested classes and functions. Original patches for code and tests by Guilherme Polo and Cheryl Sabella, respectively.

C API

• bpo-28280: Make PyMapping_Keys(), PyMapping_Values() and PyMapping_Items() always return a list (rather than a list or a tuple). Patch by Oren Milman.

• bpo-31532: Fix memory corruption due to allocator mix in getpath.c between Py_GetPath() and Py_SetPath()

• bpo-25658: Implement PEP 539 for Thread Specific Storage (TSS) API: it is a new Thread Local Storage (TLS) API to CPython which would supersede use of the existing TLS API within the CPython interpreter, while deprecating the existing API. PEP written by Erik M. Bray, patch by Masayuki Yamamoto.

Python 3.7.0 alpha 1

Release date: 2017-09-19

Security

• bpo-29781: SSLObject.version() now correctly returns None when handshake over BIO has not been performed yet.

• bpo-29505: Add fuzz tests for float(str), int(str), unicode(str); for oss-fuzz.

• bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to 2.2.3 to get security fixes.

• bpo-30730: Prevent environment variables injection in subprocess on Windows. Prevent passing other environment variables and command arguments.

• bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of multiple security vulnerabilities including: CVE-2017-9233 (External entity infinite loop DoS), CVE-2016-9063 (Integer overflow, re-fix), CVE-2016-0718 (Fix regression bugs from 2.2.0’s fix to CVE-2016-0718) and CVE-2012-0876 (Counter hash flooding with SipHash). Note: the CVE-2016-5300 (Use os-specific entropy sources like getrandom) doesn’t impact Python, since Python already gets entropy from the OS to set the expat secret using XML_SetHashSalt().

• bpo-30500: Fix urllib.parse.splithost() to correctly parse fragments. For example, splithost('//127.0.0.1#@evil.com/') now correctly returns the 127.0.0.1 host, instead of treating @evil.com as the host in an authentication (login@host).

• bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes of CVE-2016-0718 and CVE-2016-4472. See https://sourceforge.net/p/expat/bugs/537/ for more information.

Core and Builtins

• bpo-31490: Fix an assertion failure in ctypes class definition, in case the class has an attribute whose name is specified in _anonymous_ but not in _fields_. Patch by Oren Milman.

• bpo-31471: Fix an assertion failure in subprocess.Popen() on Windows, in case the env argument has a bad keys() method. Patch by Oren Milman.

• bpo-31418: Fix an assertion failure in PyErr_WriteUnraisable() in case of an exception with a bad __module__ attribute. Patch by Oren Milman.

• bpo-31416: Fix assertion failures in case of a bad warnings.filters or warnings.defaultaction. Patch by Oren Milman.

• bpo-28411: Change direct usage of PyInterpreterState.modules to PyImport_GetModuleDict(). Also introduce more uniformity in other code that deals with sys.modules. This helps reduce complications when working on sys.modules.

• bpo-28411: Switch to the abstract API when dealing with PyInterpreterState.modules. This allows later support for all dict subclasses and other Mapping implementations. Also add a PyImport_GetModule() function to reduce a bunch of duplicated code.

• bpo-31411: Raise a TypeError instead of SystemError in case warnings.onceregistry is not a dictionary. Patch by Oren Milman.

• bpo-31344: For finer control of tracing behaviour when testing the interpreter, two new frame attributes have been added to control the emission of particular trace events: f_trace_lines (True by default) to turn off per-line trace events; and f_trace_opcodes (False by default) to turn on per-opcode trace events.

• bpo-31373: Fix several possible instances of undefined behavior due to floating-point demotions.

• bpo-30465: Location information (lineno and col_offset) in f-strings is now (mostly) correct. This fixes tools like flake8 from showing warnings on the wrong line (typically the first line of the file).

• bpo-30860: Consolidate CPython’s global runtime state under a single struct. This improves discoverability of the runtime state.

• bpo-31347: Fix possible undefined behavior in _PyObject_FastCall_Prepend.

• bpo-31343: Include sys/sysmacros.h for major(), minor(), and makedev(). GNU C libray plans to remove the functions from sys/types.h.

• bpo-31291: Fix an assertion failure in zipimport.zipimporter.get_data on Windows, when the return value of pathname.replace('/','\\') isn’t a string. Patch by Oren Milman.

• bpo-31271: Fix an assertion failure in the write() method of io.TextIOWrapper, when the encoder doesn’t return a bytes object. Patch by Oren Milman.

• bpo-31243: Fix a crash in some methods of io.TextIOWrapper, when the decoder’s state is invalid. Patch by Oren Milman.

• bpo-30721: print now shows correct usage hint for using Python 2 redirection syntax. Patch by Sanyam Khurana.

• bpo-31070: Fix a race condition in importlib _get_module_lock().

• bpo-30747: Add a non-dummy implementation of _Py_atomic_store and _Py_atomic_load on MSVC.

• bpo-31095: Fix potential crash during GC caused by tp_dealloc which doesn’t call PyObject_GC_UnTrack().

• bpo-31071: Avoid masking original TypeError in call with * unpacking when other arguments are passed.

• bpo-30978: str.format_map() now passes key lookup exceptions through. Previously any exception was replaced with a KeyError exception.

• bpo-30808: Use _Py_atomic API for concurrency-sensitive signal state.

• bpo-30876: Relative import from unloaded package now reimports the package instead of failing with SystemError. Relative import from non-package now fails with ImportError rather than SystemError.

• bpo-30703: Improve signal delivery.

  Avoid using Py_AddPendingCall from signal handler, to avoid calling signal-unsafe functions. The tests I’m adding here fail without the rest of the patch, on Linux and OS X. This means our signal delivery logic had defects (some signals could be lost).

• bpo-30765: Avoid blocking in pthread_mutex_lock() when PyThread_acquire_lock() is asked not to block.

• bpo-31161: Make sure the ‘Missing parentheses’ syntax error message is only applied to SyntaxError, not to subclasses. Patch by Martijn Pieters.

• bpo-30814: Fixed a race condition when import a submodule from a package.

• bpo-30736: The internal unicodedata database has been upgraded to Unicode 10.0.

• bpo-30604: Move co_extra_freefuncs from per-thread to per-interpreter to avoid crashes.

• bpo-30597: print now shows expected input in custom error message when used as a Python 2 statement. Patch by Sanyam Khurana.

• bpo-30682: Removed a too-strict assertion that failed for certain f-strings, such as eval(“f’\n’”) and eval(“f’\r’”).

• bpo-30501: The compiler now produces more optimal code for complex condition expressions in the “if”, “while” and “assert” statement, the “if” expression, and generator expressions and comprehensions.

• bpo-28180: Implement PEP 538 (legacy C locale coercion). This means that when a suitable coercion target locale is available, both the core interpreter and locale-aware C extensions will assume the use of UTF-8 as the default text encoding, rather than ASCII.

• bpo-30486: Allows setting cell values for __closure__. Patch by Lisa Roach.

• bpo-30537: itertools.islice now accepts integer-like objects (having an __index__ method) as start, stop, and slice arguments

• bpo-25324: Tokens needed for parsing in Python moved to C. COMMENT, NL and ENCODING. This way the tokens and tok_names in the token module don’t get changed when you import the tokenize module.

• bpo-29104: Fixed parsing backslashes in f-strings.

• bpo-27945: Fixed various segfaults with dict when input collections are mutated during searching, inserting or comparing. Based on patches by Duane Griffin and Tim Mitchell.

• bpo-25794: Fixed type.__setattr__() and type.__delattr__() for non-interned attribute names. Based on patch by Eryk Sun.

• bpo-30039: If a KeyboardInterrupt happens when the interpreter is in the middle of resuming a chain of nested ‘yield from’ or ‘await’ calls, it’s now correctly delivered to the innermost frame.

• bpo-28974: object.__format__(x, '') is now equivalent to str(x) rather than format(str(self), '').

• bpo-30024: Circular imports involving absolute imports with binding a submodule to a name are now supported.

• bpo-12414: sys.getsizeof() on a code object now returns the sizes which includes the code struct and sizes of objects which it references. Patch by Dong-hee Na.

• bpo-29839: len() now raises ValueError rather than OverflowError if __len__() returned a large negative integer.

• bpo-11913: README.rst is now included in the list of distutils standard READMEs and therefore included in source distributions.

• bpo-29914: Fixed default implementations of __reduce__ and __reduce_ex__(). object.__reduce__() no longer takes arguments, object.__reduce_ex__() now requires one argument.

• bpo-29949: Fix memory usage regression of set and frozenset object.

• bpo-29935: Fixed error messages in the index() method of tuple, list and deque when pass indices of wrong type.

• bpo-29816: Shift operation now has less opportunity to raise OverflowError. ValueError always is raised rather than OverflowError for negative counts. Shifting zero with non-negative count always returns zero.

• bpo-24821: Fixed the slowing down to 25 times in the searching of some unlucky Unicode characters.

• bpo-29102: Add a unique ID to PyInterpreterState. This makes it easier to identify each subinterpreter.

• bpo-29894: The deprecation warning is emitted if __complex__ returns an instance of a strict subclass of complex. In a future versions of Python this can be an error.

• bpo-29859: Show correct error messages when any of the pthread_* calls in thread_pthread.h fails.

• bpo-29849: Fix a memory leak when an ImportError is raised during from import.

• bpo-28856: Fix an oversight that %b format for bytes should support objects follow the buffer protocol.

• bpo-29723: The sys.path[0] initialization change for bpo-29139 caused a regression by revealing an inconsistency in how sys.path is initialized when executing __main__ from a zipfile, directory, or other import location. The interpreter now consistently avoids ever adding the import location’s parent directory to sys.path, and ensures no other sys.path entries are inadvertently modified when inserting the import location named on the command line.

• bpo-29568: Escaped percent “%%” in the format string for classic string formatting no longer allows any characters between two percents.

• bpo-29714: Fix a regression that bytes format may fail when containing zero bytes inside.

• bpo-29695: bool(), float(), list() and tuple() no longer take keyword arguments. The first argument of int() can now be passes only as positional argument.

• bpo-28893: Set correct __cause__ for errors about invalid awaitables returned from __aiter__ and __anext__.

• bpo-28876: bool(range) works even if len(range) raises OverflowError.

• bpo-29683: Fixes to memory allocation in _PyCode_SetExtra. Patch by Brian Coleman.

• bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords. It should raise TypeError when kwargs is not a dict. But it might cause segv when args=NULL and kwargs is not a dict.

• bpo-28598: Support __rmod__ for subclasses of str being called before str.__mod__. Patch by Martijn Pieters.

• bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX. Patch by Matthieu Dartiailh.

• bpo-29602: Fix incorrect handling of signed zeros in complex constructor for complex subclasses and for inputs having a __complex__ method. Patch by Serhiy Storchaka.

• bpo-29347: Fixed possibly dereferencing undefined pointers when creating weakref objects.

• bpo-29463: Add docstring field to Module, ClassDef, FunctionDef, and AsyncFunctionDef ast nodes. docstring is not first stmt in their body anymore. It affects co_firstlineno and co_lnotab of code object for module and class. (Reverted in bpo-32911.)

• bpo-29438: Fixed use-after-free problem in key sharing dict.

• bpo-29546: Set the ‘path’ and ‘name’ attribute on ImportError for from ... import ....

• bpo-29546: Improve from-import error message with location

• bpo-29478: If max_line_length=None is specified while using the Compat32 policy, it is no longer ignored. Patch by Mircea Cosbuc.

• bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

• bpo-29337: Fixed possible BytesWarning when compare the code objects. Warnings could be emitted at compile time.

• bpo-29327: Fixed a crash when pass the iterable keyword argument to sorted().

• bpo-29034: Fix memory leak and use-after-free in os module (path_converter).

• bpo-29159: Fix regression in bytes(x) when x.__index__() raises Exception.

• bpo-29049: Call _PyObject_GC_TRACK() lazily when calling Python function. Calling function is up to 5% faster.

• bpo-28927: bytes.fromhex() and bytearray.fromhex() now ignore all ASCII whitespace, not only spaces. Patch by Robert Xiao.

• bpo-28932: Do not include <sys/random.h> if it does not exist.

• bpo-25677: Correct the positioning of the syntax error caret for indented blocks. Based on patch by Michael Layzell.

• bpo-29000: Fixed bytes formatting of octals with zero padding in alternate form.

• bpo-18896: Python function can now have more than 255 parameters. collections.namedtuple() now supports tuples with more than 255 elements.

• bpo-28596: The preferred encoding is UTF-8 on Android. Patch written by Chi Hsuan Yen.

• bpo-22257: Clean up interpreter startup (see PEP 432).

• bpo-26919: On Android, operating system data is now always encoded/decoded to/from UTF-8, instead of the locale encoding to avoid inconsistencies with os.fsencode() and os.fsdecode() which are already using UTF-8.

• bpo-28991: functools.lru_cache() was susceptible to an obscure reentrancy bug triggerable by a monkey-patched len() function.

• bpo-28147: Fix a memory leak in split-table dictionaries: setattr() must not convert combined table into split table. Patch written by INADA Naoki.

• bpo-28739: f-string expressions are no longer accepted as docstrings and by ast.literal_eval() even if they do not include expressions.

• bpo-28512: Fixed setting the offset attribute of SyntaxError by PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

• bpo-28918: Fix the cross compilation of xxlimited when Python has been built with Py_DEBUG defined.

• bpo-23722: Rather than silently producing a class that doesn’t support zero-argument super() in methods, failing to pass the new __classcell__ namespace entry up to type.__new__ now results in a DeprecationWarning and a class that supports zero-argument super().

• bpo-28797: Modifying the class __dict__ inside the __set_name__ method of a descriptor that is used inside that class no longer prevents calling the __set_name__ method of other descriptors.

• bpo-28799: Remove the PyEval_GetCallStats() function and deprecate the untested and undocumented sys.callstats() function. Remove the CALL_PROFILE special build: use the sys.setprofile() function, cProfile or profile to profile function calls.

• bpo-12844: More than 255 arguments can now be passed to a function.

• bpo-28782: Fix a bug in the implementation yield from when checking if the next instruction is YIELD_FROM. Regression introduced by WORDCODE (bpo-26647).

• bpo-28774: Fix error position of the unicode error in ASCII and Latin1 encoders when a string returned by the error handler contains multiple non-encodable characters (non-ASCII for the ASCII codec, characters out of the U+0000-U+00FF range for Latin1).

• bpo-28731: Optimize _PyDict_NewPresized() to create correct size dict. Improve speed of dict literal with constant keys up to 30%.

• bpo-28532: Show sys.version when -V option is supplied twice.

• bpo-27100: The with-statement now checks for __enter__ before it checks for __exit__. This gives less confusing error messages when both methods are missing. Patch by Jonathan Ellington.

• bpo-28746: Fix the set_inheritable() file descriptor method on platforms that do not have the ioctl FIOCLEX and FIONCLEX commands.

• bpo-26920: Fix not getting the locale’s charset upon initializing the interpreter, on platforms that do not have langinfo.

• bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS X when decode astral characters. Patch by Xiang Zhang.

• bpo-28665: Improve speed of the STORE_DEREF opcode by 40%.

• bpo-19398: Extra slash no longer added to sys.path components in case of empty compile-time PYTHONPATH components.

• bpo-28621: Sped up converting int to float by reusing faster bits counting implementation. Patch by Adrian Wielgosik.

• bpo-28580: Optimize iterating split table values. Patch by Xiang Zhang.

• bpo-28583: PyDict_SetDefault didn’t combine split table when needed. Patch by Xiang Zhang.

• bpo-28128: Deprecation warning for invalid str and byte escape sequences now prints better information about where the error occurs. Patch by Serhiy Storchaka and Eric Smith.

• bpo-28509: dict.update() no longer allocate unnecessary large memory.

• bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in debug build.

• bpo-28517: Fixed of-by-one error in the peephole optimizer that caused keeping unreachable code.

• bpo-28214: Improved exception reporting for problematic __set_name__ attributes.

• bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and exception loss in PyTraceBack_Here().

• bpo-28183: Optimize and cleanup dict iteration.

• bpo-26081: Added C implementation of asyncio.Future. Original patch by Yury Selivanov.

• bpo-28379: Added sanity checks and tests for PyUnicode_CopyCharacters(). Patch by Xiang Zhang.

• bpo-28376: The type of long range iterator is now registered as Iterator. Patch by Oren Milman.

• bpo-28376: Creating instances of range_iterator by calling range_iterator type now is disallowed. Calling iter() on range instance is the only way. Patch by Oren Milman.

• bpo-26906: Resolving special methods of uninitialized type now causes implicit initialization of the type instead of a fail.

• bpo-18287: PyType_Ready() now checks that tp_name is not NULL. Original patch by Niklas Koep.

• bpo-24098: Fixed possible crash when AST is changed in process of compiling it.

• bpo-28201: Dict reduces possibility of 2nd conflict in hash table when hashes have same lower bits.

• bpo-28350: String constants with null character no longer interned.

• bpo-26617: Fix crash when GC runs during weakref callbacks.

• bpo-27942: String constants now interned recursively in tuples and frozensets.

• bpo-28289: ImportError.__init__ now resets not specified attributes.

• bpo-21578: Fixed misleading error message when ImportError called with invalid keyword args.

• bpo-28203: Fix incorrect type in complex(1.0, {2:3}) error message. Patch by Soumya Sharma.

• bpo-28086: Single var-positional argument of tuple subtype was passed unscathed to the C-defined function. Now it is converted to exact tuple.

• bpo-28214: Now __set_name__ is looked up on the class instead of the instance.

• bpo-27955: Fallback on reading /dev/urandom device when the getrandom() syscall fails with EPERM, for example when blocked by SECCOMP.

• bpo-28192: Don’t import readline in isolated mode.

• bpo-27441: Remove some redundant assignments to ob_size in longobject.c. Thanks Oren Milman.

• bpo-27222: Clean up redundant code in long_rshift function. Thanks Oren Milman.

• Upgrade internal unicode databases to Unicode version 9.0.0.

• bpo-28131: Fix a regression in zipimport’s compile_source(). zipimport should use the same optimization level as the interpreter.

• bpo-28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properly optimize memcpy().

• bpo-28120: Fix dict.pop() for splitted dictionary when trying to remove a “pending key” (Not yet inserted in split-table). Patch by Xiang Zhang.

• bpo-26182: Raise DeprecationWarning when async and await keywords are used as variable/attribute/class/function name.

• bpo-26182: Fix a refleak in code that raises DeprecationWarning.

• bpo-28721: Fix asynchronous generators aclose() and athrow() to handle StopAsyncIteration propagation properly.

• bpo-26110: Speed-up method calls: add LOAD_METHOD and CALL_METHOD opcodes.

Library

• bpo-31499: xml.etree: Fix a crash when a parser is part of a reference cycle.

• bpo-31482: random.seed() now works with bytes in version=1

• bpo-28556: typing.get_type_hints now finds the right globalns for classes and modules by default (when no globalns was specified by the caller).

• bpo-28556: Speed improvements to the typing module. Original PRs by Ivan Levkivskyi and Mitar.

• bpo-31544: The C accelerator module of ElementTree ignored exceptions raised when looking up TreeBuilder target methods in XMLParser().

• bpo-31234: socket.create_connection() now fixes manually a reference cycle: clear the variable storing the last exception on success.

• bpo-31457: LoggerAdapter objects can now be nested.

• bpo-31431: SSLContext.check_hostname now automatically sets SSLContext.verify_mode to ssl.CERT_REQUIRED instead of failing with a ValueError.

• bpo-31233: socketserver.ThreadingMixIn now keeps a list of non-daemonic threads to wait until all these threads complete in server_close().

• bpo-28638: Changed the implementation strategy for collections.namedtuple() to substantially reduce the use of exec() in favor of precomputed methods. As a result, the verbose parameter and _source attribute are no longer supported. The benefits include 1) having a smaller memory footprint for applications using multiple named tuples, 2) faster creation of the named tuple class (approx 4x to 6x depending on how it is measured), and 3) minor speed-ups for instance creation using __new__, _make, and _replace. (The primary patch contributor is Jelle Zijlstra with further improvements by INADA Naoki, Serhiy Storchaka, and Raymond Hettinger.)

• bpo-31400: Improves SSL error handling to avoid losing error numbers.

• bpo-27629: Make return types of SSLContext.wrap_bio() and SSLContext.wrap_socket() customizable.

• bpo-28958: ssl.SSLContext() now uses OpenSSL error information when a context cannot be instantiated.

• bpo-28182: The SSL module now raises SSLCertVerificationError when OpenSSL fails to verify the peer’s certificate. The exception contains more information about the error.

• bpo-27340: SSLSocket.sendall() now uses memoryview to create slices of data. This fixes support for all bytes-like object. It is also more efficient and avoids costly copies.

• bpo-14191: A new function argparse.ArgumentParser.parse_intermixed_args provides the ability to parse command lines where there user intermixes options and positional arguments.

• bpo-31178: Fix string concatenation bug in rare error path in the subprocess module

• bpo-31350: Micro-optimize asyncio._get_running_loop() to become up to 10% faster.

• bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying of partial characters for UTF-8 input (libexpat bug 115): https://github.com/libexpat/libexpat/issues/115

• bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

• bpo-1198569: string.Template subclasses can optionally define braceidpattern if they want to specify different placeholder patterns inside and outside the braces. If None (the default) it falls back to idpattern.

• bpo-31326: concurrent.futures.ProcessPoolExecutor.shutdown() now explicitly closes the call queue. Moreover, shutdown(wait=True) now also join the call queue thread, to prevent leaking a dangling thread.

• bpo-27144: The map() and as_completed() iterators in concurrent.futures now avoid keeping a reference to yielded objects.

• bpo-31281: Fix fileinput.FileInput(files, inplace=True) when files contain pathlib.Path objects.

• bpo-10746: Fix ctypes producing wrong PEP 3118 type codes for integer types.

• bpo-27584: AF_VSOCK has been added to the socket interface which allows communication between virtual machines and their host.

• bpo-22536: The subprocess module now sets the filename when FileNotFoundError is raised on POSIX systems due to the executable or cwd not being found.

• bpo-29741: Update some methods in the _pyio module to also accept integer types. Patch by Oren Milman.

• bpo-31249: concurrent.futures: WorkItem.run() used by ThreadPoolExecutor now breaks a reference cycle between an exception object and the WorkItem object.

• bpo-31247: xmlrpc.server now explicitly breaks reference cycles when using sys.exc_info() in code handling exceptions.

• bpo-23835: configparser: reading defaults in the ConfigParser() constructor is now using read_dict(), making its behavior consistent with the rest of the parser. Non-string keys and values in the defaults dictionary are now being implicitly converted to strings. Patch by James Tocknell.

• bpo-31238: pydoc: the stop() method of the private ServerThread class now waits until DocServer.serve_until_quit() completes and then explicitly sets its docserver attribute to None to break a reference cycle.

• bpo-5001: Many asserts in multiprocessing are now more informative, and some error types have been changed to more specific ones.

• bpo-31109: Convert zipimport to use Argument Clinic.

• bpo-30102: The ssl and hashlib modules now call OPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The function detects CPU features and enables optimizations on some CPU architectures such as POWER8. Patch is based on research from Gustavo Serra Scalet.

• bpo-18966: Non-daemonic threads created by a multiprocessing.Process are now joined on child exit.

• bpo-31183: dis now works with asynchronous generator and coroutine objects. Patch by George Collins based on diagnosis by Luciano Ramalho.

• bpo-5001: There are a number of uninformative asserts in the multiprocessing module, as noted in issue 5001. This change fixes two of the most potentially problematic ones, since they are in error-reporting code, in the multiprocessing.managers.convert_to_error function. (It also makes more informative a ValueError message.) The only potentially problematic change is that the AssertionError is now a TypeError; however, this should also help distinguish it from an AssertionError being reported by the function/its caller (such as in issue 31169). - Patch by Allen W. Smith (drallensmith on github).

• bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

• bpo-31151: socketserver.ForkingMixIn.server_close() now waits until all child processes completed to prevent leaking zombie processes.

• bpo-31072: Add an include_file parameter to zipapp.create_archive()

• bpo-24700: Optimize array.array comparison. It is now from 10x up to 70x faster when comparing arrays holding values of the same integer type.

• bpo-31135: ttk: fix the destroy() method of LabeledScale and OptionMenu classes. Call the parent destroy() method even if the used attribute doesn’t exist. The LabeledScale.destroy() method now also explicitly clears label and scale attributes to help the garbage collector to destroy all widgets.

• bpo-31107: Fix copyreg._slotnames() mangled attribute calculation for classes whose name begins with an underscore. Patch by Shane Harvey.

• bpo-31080: Allow logging.config.fileConfig to accept kwargs and/or args.

• bpo-30897: pathlib.Path objects now include an is_mount() method (only implemented on POSIX). This is similar to os.path.ismount(p). Patch by Cooper Ry Lees.

• bpo-31061: Fixed a crash when using asyncio and threads.

• bpo-30987: Added support for CAN ISO-TP protocol in the socket module.

• bpo-30522: Added a setStream method to logging.StreamHandler to allow the stream to be set after creation.

• bpo-30502: Fix handling of long oids in ssl. Based on patch by Christian Heimes.

• bpo-5288: Support tzinfo objects with sub-minute offsets.

• bpo-30919: Fix shared memory performance regression in multiprocessing in 3.x.

  Shared memory used anonymous memory mappings in 2.x, while 3.x mmaps actual files. Try to be careful to do as little disk I/O as possible.

• bpo-26732: Fix too many fds in processes started with the “forkserver” method.

  A child process would inherit as many fds as the number of still-running children.

• bpo-29403: Fix unittest.mock’s autospec to not fail on method-bound builtin functions. Patch by Aaron Gallagher.

• bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

• bpo-19896: Fix multiprocessing.sharedctypes to recognize typecodes 'q' and 'Q'.

• bpo-30946: Remove obsolete code in readline module for platforms where GNU readline is older than 2.1 or where select() is not available.

• bpo-25684: Change ttk.OptionMenu radiobuttons to be unique across instances of OptionMenu.

• bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits until the thread completes, even if the thread was started by the same process which created the queue.

• bpo-29854: Fix segfault in readline when using readline’s history-size option. Patch by Nir Soffer.

• bpo-30794: Added multiprocessing.Process.kill method to terminate using the SIGKILL signal on Unix.

• bpo-30319: socket.close() now ignores ECONNRESET error.

• bpo-30828: Fix out of bounds write in asyncio.CFuture.remove_done_callback().

• bpo-30302: Use keywords in the repr of datetime.timedelta.

• bpo-30807: signal.setitimer() may disable the timer when passed a tiny value.

  Tiny values (such as 1e-6) are valid non-zero values for setitimer(), which is specified as taking microsecond-resolution intervals. However, on some platform, our conversion routine could convert 1e-6 into a zero interval, therefore disabling the timer instead of (re-)scheduling it.

• bpo-30441: Fix bug when modifying os.environ while iterating over it

• bpo-29585: Avoid importing sysconfig from site to improve startup speed. Python startup is about 5% faster on Linux and 30% faster on macOS.

• bpo-29293: Add missing parameter “n” on multiprocessing.Condition.notify().

  The doc claims multiprocessing.Condition behaves like threading.Condition, but its notify() method lacked the optional “n” argument (to specify the number of sleepers to wake up) that threading.Condition.notify() accepts.

• bpo-30532: Fix email header value parser dropping folding white space in certain cases.

• bpo-30596: Add a close() method to multiprocessing.Process.

• bpo-9146: Fix a segmentation fault in _hashopenssl when standard hash functions such as md5 are not available in the linked OpenSSL library. As in some special FIPS-140 build environments.

• bpo-29169: Update zlib to 1.2.11.

• bpo-30119: ftplib.FTP.putline() now throws ValueError on commands that contains CR or LF. Patch by Dong-hee Na.

• bpo-30879: os.listdir() and os.scandir() now emit bytes names when called with bytes-like argument.

• bpo-30746: Prohibited the ‘=’ character in environment variable names in os.putenv() and os.spawn*().

• bpo-30664: The description of a unittest subtest now preserves the order of keyword arguments of TestCase.subTest().

• bpo-21071: struct.Struct.format type is now str instead of bytes.

• bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads to have a non repr() based thread name by default when no thread_name_prefix is supplied. They will now identify themselves as “ThreadPoolExecutor-y_n”.

• bpo-29755: Fixed the lgettext() family of functions in the gettext module. They now always return bytes.

• bpo-30616: Functional API of enum allows to create empty enums. Patched by Dong-hee Na

• bpo-30038: Fix race condition between signal delivery and wakeup file descriptor. Patch by Nathaniel Smith.

• bpo-23894: lib2to3 now recognizes rb'...' and f'...' strings.

• bpo-24744: pkgutil.walk_packages function now raises ValueError if path is a string. Patch by Sanyam Khurana.

• bpo-24484: Avoid race condition in multiprocessing cleanup.

• bpo-30589: Fix multiprocessing.Process.exitcode to return the opposite of the signal number when the process is killed by a signal (instead of 255) when using the “forkserver” method.

• bpo-28994: The traceback no longer displayed for SystemExit raised in a callback registered by atexit.

• bpo-30508: Don’t log exceptions if Task/Future “cancel()” method was called.

• bpo-30645: Fix path calculation in imp.load_package(), fixing it for cases when a package is only shipped with bytecodes. Patch by Alexandru Ardelean.

• bpo-11822: The dis.dis() function now is able to disassemble nested code objects.

• bpo-30624: selectors does not take KeyboardInterrupt and SystemExit into account, leaving a fd in a bad state in case of error. Patch by Giampaolo Rodola’.

• bpo-30595: multiprocessing.Queue.get() with a timeout now polls its reader in non-blocking mode if it succeeded to acquire the lock but the acquire took longer than the timeout.

• bpo-28556: Updates to typing module: Add generic AsyncContextManager, add support for ContextManager on all versions. Original PRs by Jelle Zijlstra and Ivan Levkivskyi

• bpo-30605: re.compile() no longer raises a BytesWarning when compiling a bytes instance with misplaced inline modifier. Patch by Roy Williams.

• bpo-29870: Fix ssl sockets leaks when connection is aborted in asyncio/ssl implementation. Patch by Michaël Sghaïer.

• bpo-29743: Closing transport during handshake process leaks open socket. Patch by Nikolay Kim

• bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by Mathieu Sornay.

• bpo-30014: modify() method of poll(), epoll() and devpoll() based classes of selectors module is around 10% faster. Patch by Giampaolo Rodola’.

• bpo-30418: On Windows, subprocess.Popen.communicate() now also ignore EINVAL on stdin.write() if the child process is still running but closed the pipe.

• bpo-30463: Addded empty __slots__ to abc.ABC. This allows subclassers to deny __dict__ and __weakref__ creation. Patch by Aaron Hall.

• bpo-30520: Loggers are now pickleable.

• bpo-30557: faulthandler now correctly filters and displays exception codes on Windows

• bpo-30526: Add TextIOWrapper.reconfigure() and a TextIOWrapper.write_through attribute.

• bpo-30245: Fix possible overflow when organize struct.pack_into error message. Patch by Yuan Liu.

• bpo-30378: Fix the problem that logging.handlers.SysLogHandler cannot handle IPv6 addresses.

• bpo-16500: Allow registering at-fork handlers.

• bpo-30470: Deprecate invalid ctypes call protection on Windows. Patch by Mariatta Wijaya.

• bpo-30414: multiprocessing.Queue._feed background running thread do not break from main loop on exception.

• bpo-30003: Fix handling escape characters in HZ codec. Based on patch by Ma Lin.

• bpo-30149: inspect.signature() now supports callables with variable-argument parameters wrapped with partialmethod. Patch by Dong-hee Na.

• bpo-30436: importlib.find_spec() raises ModuleNotFoundError instead of AttributeError if the specified parent module is not a package (i.e. lacks a __path__ attribute).

• bpo-30301: Fix AttributeError when using SimpleQueue.empty() under spawn and forkserver start methods.

• bpo-30375: Warnings emitted when compile a regular expression now always point to the line in the user code. Previously they could point into inners of the re module if emitted from inside of groups or conditionals.

• bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted. This error occurs sometimes on SSL connections.

• bpo-29196: Removed previously deprecated in Python 2.4 classes Plist, Dict and _InternalDict in the plistlib module. Dict values in the result of functions readPlist() and readPlistFromBytes() are now normal dicts. You no longer can use attribute access to access items of these dictionaries.

• bpo-9850: The macpath is now deprecated and will be removed in Python 3.8.

• bpo-30299: Compiling regular expression in debug mode on CPython now displays the compiled bytecode in human readable form.

• bpo-30048: Fixed Task.cancel() can be ignored when the task is running coroutine and the coroutine returned without any more await.

• bpo-30266: contextlib.AbstractContextManager now supports anti-registration by setting __enter__ = None or __exit__ = None, following the pattern introduced in bpo-25958. Patch by Jelle Zijlstra.

• bpo-30340: Enhanced regular expressions optimization. This increased the performance of matching some patterns up to 25 times.

• bpo-30298: Weaken the condition of deprecation warnings for inline modifiers. Now allowed several subsequential inline modifiers at the start of the pattern (e.g. '(?i)(?s)...'). In verbose mode whitespaces and comments now are allowed before and between inline modifiers (e.g. '(?x) (?i) (?s)...').

• bpo-30285: Optimized case-insensitive matching and searching of regular expressions.

• bpo-29990: Fix range checking in GB18030 decoder. Original patch by Ma Lin.

• bpo-29979: rewrite cgi.parse_multipart, reusing the FieldStorage class and making its results consistent with those of FieldStorage for multipart/form-data requests. Patch by Pierre Quentel.

• bpo-30243: Removed the __init__ methods of _json’s scanner and encoder. Misusing them could cause memory leaks or crashes. Now scanner and encoder objects are completely initialized in the __new__ methods.

• bpo-30215: Compiled regular expression objects with the re.LOCALE flag no longer depend on the locale at compile time. Only the locale at matching time affects the result of matching.

• bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper process when Ctrl-C is received.

• bpo-30103: binascii.b2a_uu() and uu.encode() now support using '`' as zero instead of space.

• bpo-28556: Various updates to typing module: add typing.NoReturn type, use WrapperDescriptorType, minor bug-fixes. Original PRs by Jim Fasarakis-Hilliard and Ivan Levkivskyi.

• bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

• bpo-30228: The seek() and tell() methods of io.FileIO now set the internal seekable attribute to avoid one syscall on open() (in buffered or text mode).

• bpo-30190: unittest’s assertAlmostEqual and assertNotAlmostEqual provide a better message in case of failure which includes the difference between left and right arguments. (patch by Giampaolo Rodola’)

• bpo-30101: Add support for curses.A_ITALIC.

• bpo-29822: inspect.isabstract() now works during __init_subclass__. Patch by Nate Soares.

• bpo-29960: Preserve generator state when _random.Random.setstate() raises an exception. Patch by Bryan Olson.

• bpo-30070: Fixed leaks and crashes in errors handling in the parser module.

• bpo-22352: Column widths in the output of dis.dis() are now adjusted for large line numbers and instruction offsets.

• bpo-30061: Fixed crashes in IOBase methods __next__() and readlines() when readline() or __next__() respectively return non-sizeable object. Fixed possible other errors caused by not checking results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

• bpo-30218: Fix PathLike support for shutil.unpack_archive. Patch by Jelle Zijlstra.

• bpo-10076: Compiled regular expression and match objects in the re module now support copy.copy() and copy.deepcopy() (they are considered atomic).

• bpo-30068: _io._IOBase.readlines will check if it’s closed first when hint is present.

• bpo-29694: Fixed race condition in pathlib mkdir with flags parents=True. Patch by Armin Rigo.

• bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions in contextlib.contextmanager. Patch by Siddharth Velankar.

• bpo-26187: Test that sqlite3 trace callback is not called multiple times when schema is changing. Indirectly fixed by switching to use sqlite3_prepare_v2() in bpo-9303. Patch by Aviv Palivoda.

• bpo-30017: Allowed calling the close() method of the zip entry writer object multiple times. Writing to a closed writer now always produces a ValueError.

• bpo-29998: Pickling and copying ImportError now preserves name and path attributes.

• bpo-29995: re.escape() now escapes only regex special characters.

• bpo-29962: Add math.remainder operation, implementing remainder as specified in IEEE 754.

• bpo-29649: Improve struct.pack_into() exception messages for problems with the buffer size and offset. Patch by Andrew Nester.

• bpo-29654: Support If-Modified-Since HTTP header (browser cache). Patch by Pierre Quentel.

• bpo-29931: Fixed comparison check for ipaddress.ip_interface objects. Patch by Sanjay Sundaresan.

• bpo-29953: Fixed memory leaks in the replace() method of datetime and time objects when pass out of bound fold argument.

• bpo-29942: Fix a crash in itertools.chain.from_iterable when encountering long runs of empty iterables.

• bpo-10030: Sped up reading encrypted ZIP files by 2 times.

• bpo-29204: Element.getiterator() and the html parameter of XMLParser() were deprecated only in the documentation (since Python 3.2 and 3.4 correspondintly). Now using them emits a deprecation warning.

• bpo-27863: Fixed multiple crashes in ElementTree caused by race conditions and wrong types.

• bpo-25996: Added support of file descriptors in os.scandir() on Unix. os.fwalk() is sped up by 2 times by using os.scandir().

• bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising an exception at the very first of an iterable may swallow the exception or make the program hang. Patch by Davin Potts and Xiang Zhang.

• bpo-23890: unittest.TestCase.assertRaises() now manually breaks a reference cycle to not keep objects alive longer than expected.

• bpo-29901: The zipapp module now supports general path-like objects, not just pathlib.Path.

• bpo-25803: Avoid incorrect errors raised by Path.mkdir(exist_ok=True) when the OS gives priority to errors such as EACCES over EEXIST.

• bpo-29861: Release references to tasks, their arguments and their results as soon as they are finished in multiprocessing.Pool.

• bpo-19930: The mode argument of os.makedirs() no longer affects the file permission bits of newly-created intermediate-level directories.

• bpo-29884: faulthandler: Restore the old sigaltstack during teardown. Patch by Christophe Zeitouny.

• bpo-25455: Fixed crashes in repr of recursive buffered file-like objects.

• bpo-29800: Fix crashes in partial.__repr__ if the keys of partial.keywords are not strings. Patch by Michael Seifert.

• bpo-8256: Fixed possible failing or crashing input() if attributes “encoding” or “errors” of sys.stdin or sys.stdout are not set or are not strings.

• bpo-28692: Using non-integer value for selecting a plural form in gettext is now deprecated.

• bpo-26121: Use C library implementation for math functions erf() and erfc().

• bpo-29619: os.stat() and os.DirEntry.inode() now convert inode (st_ino) using unsigned integers.

• bpo-28298: Fix a bug that prevented array ‘Q’, ‘L’ and ‘I’ from accepting big intables (objects that have __int__) as elements.

• bpo-29645: Speed up importing the webbrowser module. webbrowser.register() is now thread-safe.

• bpo-28231: The zipfile module now accepts path-like objects for external paths.

• bpo-26915: index() and count() methods of collections.abc.Sequence now check identity before checking equality when do comparisons.

• bpo-28682: Added support for bytes paths in os.fwalk().

• bpo-29728: Add new socket.TCP_NOTSENT_LOWAT (Linux 3.12) constant. Patch by Nathaniel J. Smith.

• bpo-29623: Allow use of path-like object as a single argument in ConfigParser.read(). Patch by David Ellis.

• bpo-9303: Migrate sqlite3 module to _v2 API. Patch by Aviv Palivoda.

• bpo-28963: Fix out of bound iteration in asyncio.Future.remove_done_callback implemented in C.

• bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer closes before all pipes are closed.

• bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C to accept None argument as their pure Python implementation.

• bpo-29703: Fix asyncio to support instantiation of new event loops in child processes.

• bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any other exception) to exception(s) raised in the dispatched methods. Patch by Petr Motejlek.

• bpo-7769: Method register_function() of xmlrpc.server.SimpleXMLRPCDispatcher and its subclasses can now be used as a decorator.

• bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

• bpo-28624: Add a test that checks that cwd parameter of Popen() accepts PathLike objects. Patch by Sayan Chowdhury.

• bpo-28518: Start a transaction implicitly before a DML statement. Patch by Aviv Palivoda.

• bpo-29742: get_extra_info() raises exception if get called on closed ssl transport. Patch by Nikolay Kim.

• bpo-16285: urllib.parse.quote is now based on RFC 3986 and hence includes ‘~’ in the set of characters that is not quoted by default. Patch by Christian Theune and Ratnadeep Debnath.

• bpo-29532: Altering a kwarg dictionary passed to functools.partial() no longer affects a partial object after creation.

• bpo-29110: Fix file object leak in aifc.open() when file is given as a filesystem path and is not in valid AIFF format. Patch by Anthony Zhang.

• bpo-22807: Add uuid.SafeUUID and uuid.UUID.is_safe to relay information from the platform about whether generated UUIDs are generated with a multiprocessing safe method.

• bpo-29576: Improve some deprecations in importlib. Some deprecated methods now emit DeprecationWarnings and have better descriptive messages.

• bpo-29534: Fixed different behaviour of Decimal.from_float() for _decimal and _pydecimal. Thanks Andrew Nester.

• bpo-10379: locale.format_string now supports the ‘monetary’ keyword argument, and locale.format is deprecated.

• bpo-29851: importlib.reload() now raises ModuleNotFoundError if the module lacks a spec.

• bpo-28556: Various updates to typing module: typing.Counter, typing.ChainMap, improved ABC caching, etc. Original PRs by Jelle Zijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

• bpo-29100: Fix datetime.fromtimestamp() regression introduced in Python 3.6.0: check minimum and maximum years.

• bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

• bpo-29444: Fixed out-of-bounds buffer access in the group() method of the match object. Based on patch by WGH.

• bpo-29377: Add WrapperDescriptorType, MethodWrapperType, and MethodDescriptorType built-in types to types module. Original patch by Manuel Krebber.

• bpo-29218: Unused install_misc command is now removed. It has been documented as unused since 2000. Patch by Eric N. Vander Weele.

• bpo-29368: The extend() method is now called instead of the append() method when unpickle collections.deque and other list-like objects. This can speed up unpickling to 2 times.

• bpo-29338: The help of a builtin or extension class now includes the constructor signature if __text_signature__ is provided for the class.

• bpo-29335: Fix subprocess.Popen.wait() when the child process has exited to a stopped instead of terminated state (ex: when under ptrace).

• bpo-29290: Fix a regression in argparse that help messages would wrap at non-breaking spaces.

• bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

• bpo-29197: Removed deprecated function ntpath.splitunc().

• bpo-29210: Removed support of deprecated argument “exclude” in tarfile.TarFile.add().

• bpo-29219: Fixed infinite recursion in the repr of uninitialized ctypes.CDLL instances.

• bpo-29192: Removed deprecated features in the http.cookies module.

• bpo-29193: A format string argument for string.Formatter.format() is now positional-only.

• bpo-29195: Removed support of deprecated undocumented keyword arguments in methods of regular expression objects.

• bpo-28969: Fixed race condition in C implementation of functools.lru_cache. KeyError could be raised when cached function with full cache was simultaneously called from differen threads with the same uncached arguments.

• bpo-20804: The unittest.mock.sentinel attributes now preserve their identity when they are copied or pickled.

• bpo-29142: In urllib.request, suffixes in no_proxy environment variable with leading dots could match related hostnames again (e.g. .b.c matches a.b.c). Patch by Milan Oberkirch.

• bpo-28961: Fix unittest.mock._Call helper: don’t ignore the name parameter anymore. Patch written by Jiajun Huang.

• bpo-15812: inspect.getframeinfo() now correctly shows the first line of a context. Patch by Sam Breese.

• bpo-28985: Update authorizer constants in sqlite3 module. Patch by Dingyuan Wang.

• bpo-29079: Prevent infinite loop in pathlib.resolve() on Windows

• bpo-13051: Fixed recursion errors in large or resized curses.textpad.Textbox. Based on patch by Tycho Andersen.

• bpo-9770: curses.ascii predicates now work correctly with negative integers.

• bpo-28427: old keys should not remove new values from WeakValueDictionary when collecting from another thread.

• bpo-28923: Remove editor artifacts from Tix.py.

• bpo-28871: Fixed a crash when deallocate deep ElementTree.

• bpo-19542: Fix bugs in WeakValueDictionary.setdefault() and WeakValueDictionary.pop() when a GC collection happens in another thread.

• bpo-20191: Fixed a crash in resource.prlimit() when passing a sequence that doesn’t own its elements as limits.

• bpo-16255: subprocess.Popen uses /system/bin/sh on Android as the shell, instead of /bin/sh.

• bpo-28779: multiprocessing.set_forkserver_preload() would crash the forkserver process if a preloaded module instantiated some multiprocessing objects such as locks.

• bpo-26937: The chown() method of the tarfile.TarFile class does not fail now when the grp module cannot be imported, as for example on Android platforms.

• bpo-28847: dbm.dumb now supports reading read-only files and no longer writes the index file when it is not changed. A deprecation warning is now emitted if the index file is missed and recreated in the ‘r’ and ‘w’ modes (will be an error in future Python releases).

• bpo-27030: Unknown escapes consisting of '\' and an ASCII letter in re.sub() replacement templates regular expressions now are errors.

• bpo-28835: Fix a regression introduced in warnings.catch_warnings(): call warnings.showwarning() if it was overridden inside the context manager.

• bpo-27172: To assist with upgrades from 2.7, the previously documented deprecation of inspect.getfullargspec() has been reversed. This decision may be revisited again after the Python 2.7 branch is no longer officially supported.

• bpo-28740: Add sys.getandroidapilevel(): return the build time API version of Android as an integer. Function only available on Android.

• bpo-26273: Add new socket.TCP_CONGESTION (Linux 2.6.13) and socket.TCP_USER_TIMEOUT (Linux 2.6.37) constants. Patch written by Omar Sandoval.

• bpo-28752: Restored the __reduce__() methods of datetime objects.

• bpo-28727: Regular expression patterns, _sre.SRE_Pattern objects created by re.compile(), become comparable (only x==y and x!=y operators). This change should fix the bpo-18383: don’t duplicate warning filters when the warnings module is reloaded (thing usually only done in unit tests).

• bpo-20572: Remove the subprocess.Popen.wait endtime parameter. It was deprecated in 3.4 and undocumented prior to that.

• bpo-25659: In ctypes, prevent a crash calling the from_buffer() and from_buffer_copy() methods on abstract classes like Array.

• bpo-28548: In the “http.server” module, parse the protocol version if possible, to avoid using HTTP 0.9 in some error responses.

• bpo-19717: Makes Path.resolve() succeed on paths that do not exist. Patch by Vajrasky Kok

• bpo-28563: Fixed possible DoS and arbitrary code execution when handle plural form selections in the gettext module. The expression parser now supports exact syntax supported by GNU gettext.

• bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator when the garbage collector is invoked in other thread. Based on patch by Sebastian Cufre.

• bpo-27517: LZMA compressor and decompressor no longer raise exceptions if given empty data twice. Patch by Benjamin Fogle.

• bpo-28549: Fixed segfault in curses’s addch() with ncurses6.

• bpo-28449: tarfile.open() with mode “r” or “r:” now tries to open a tar file with compression before trying to open it without compression. Otherwise it had 50% chance failed with ignore_zeros=True.

• bpo-23262: The webbrowser module now supports Firefox 36+ and derived browsers. Based on patch by Oleg Broytman.

• bpo-24241: The webbrowser in an X environment now prefers using the default browser directly. Also, the webbrowser register() function now has a documented ‘preferred’ argument, to specify browsers to be returned by get() with no arguments. Patch by David Steele

• bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale caused by representing the scale as float value internally in Tk. tkinter.IntVar now works if float value is set to underlying Tk variable.

• bpo-28255: calendar.TextCalendar.prweek() no longer prints a space after a weeks’s calendar. calendar.TextCalendar.pryear() no longer prints redundant newline after a year’s calendar. Based on patch by Xiang Zhang.

• bpo-28255: calendar.TextCalendar.prmonth() no longer prints a space at the start of new line after printing a month’s calendar. Patch by Xiang Zhang.

• bpo-20491: The textwrap.TextWrapper class now honors non-breaking spaces. Based on patch by Kaarle Ritvanen.

• bpo-28353: os.fwalk() no longer fails on broken links.

• bpo-28430: Fix iterator of C implemented asyncio.Future doesn’t accept non-None value is passed to it.send(val).

• bpo-27025: Generated names for Tkinter widgets now start by the “!” prefix for readability.

• bpo-25464: Fixed HList.header_exists() in tkinter.tix module by addin a workaround to Tix library bug.

• bpo-28488: shutil.make_archive() no longer adds entry “./” to ZIP archive.

• bpo-25953: re.sub() now raises an error for invalid numerical group reference in replacement template even if the pattern is not found in the string. Error message for invalid group reference now includes the group index and the position of the reference. Based on patch by SilentGhost.

• bpo-28469: timeit now uses the sequence 1, 2, 5, 10, 20, 50,… instead of 1, 10, 100,… for autoranging.

• bpo-28115: Command-line interface of the zipfile module now uses argparse. Added support of long options.

• bpo-18219: Optimize csv.DictWriter for large number of columns. Patch by Mariatta Wijaya.

• bpo-28448: Fix C implemented asyncio.Future didn’t work on Windows.

• bpo-23214: In the “io” module, the argument to BufferedReader and BytesIO’s read1() methods is now optional and can be -1, matching the BufferedIOBase specification.

• bpo-28480: Fix error building socket module when multithreading is disabled.

• bpo-28240: timeit: remove -c/--clock and -t/--time command line options which were deprecated since Python 3.3.

• bpo-28240: timeit now repeats the benchmarks 5 times instead of only 3 to make benchmarks more reliable.

• bpo-28240: timeit autorange now uses a single loop iteration if the benchmark takes less than 10 seconds, instead of 10 iterations. “python3 -m timeit -s ‘import time’ ‘time.sleep(1)’” now takes 4 seconds instead of 40 seconds.

• Distutils.sdist now looks for README and setup.py files with case sensitivity. This behavior matches that found in Setuptools 6.0 and later. See setuptools 100 for rationale.

• bpo-24452: Make webbrowser support Chrome on Mac OS X. Patch by Ned Batchelder.

• bpo-20766: Fix references leaked by pdb in the handling of SIGINT handlers.

• bpo-27998: Fixed bytes path support in os.scandir() on Windows. Patch by Eryk Sun.

• bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

• bpo-28380: unittest.mock Mock autospec functions now properly support assert_called, assert_not_called, and assert_called_once.

• bpo-28229: lzma module now supports pathlib.

• bpo-28321: Fixed writing non-BMP characters with binary format in plistlib.

• bpo-28225: bz2 module now supports pathlib. Initial patch by Ethan Furman.

• bpo-28227: gzip now supports pathlib. Patch by Ethan Furman.

• bpo-28332: Deprecated silent truncations in socket.htons and socket.ntohs. Original patch by Oren Milman.

• bpo-27358: Optimized merging var-keyword arguments and improved error message when passing a non-mapping as a var-keyword argument.

• bpo-28257: Improved error message when passing a non-iterable as a var-positional argument. Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

• bpo-28322: Fixed possible crashes when unpickle itertools objects from incorrect pickle data. Based on patch by John Leitch.

• bpo-28228: imghdr now supports pathlib.

• bpo-28226: compileall now supports pathlib.

• bpo-28314: Fix function declaration (C flags) for the getiterator() method of xml.etree.ElementTree.Element.

• bpo-28148: Stop using localtime() and gmtime() in the time module.

  Introduced platform independent _PyTime_localtime API that is similar to POSIX localtime_r, but available on all platforms. Patch by Ed Schouten.

• bpo-28253: Fixed calendar functions for extreme months: 0001-01 and 9999-12.

  Methods itermonthdays() and itermonthdays2() are reimplemented so that they don’t call itermonthdates() which can cause datetime.date under/overflow.

• bpo-28275: Fixed possible use after free in the decompress() methods of the LZMADecompressor and BZ2Decompressor classes. Original patch by John Leitch.

• bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation() if pass invalid string-like object as a name. Patch by Xiang Zhang.

• bpo-18844: random.choices() now has k as a keyword-only argument to improve the readability of common cases and come into line with the signature used in other languages.

• bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py. Patch by Madison May.

• bpo-27611: Fixed support of default root window in the tkinter.tix module. Added the master parameter in the DisplayStyle constructor.

• bpo-27348: In the traceback module, restore the formatting of exception messages like “Exception: None”. This fixes a regression introduced in 3.5a2.

• bpo-25651: Allow falsy values to be used for msg parameter of subTest().

• bpo-27778: Fix a memory leak in os.getrandom() when the getrandom() is interrupted by a signal and a signal handler raises a Python exception.

• bpo-28200: Fix memory leak on Windows in the os module (fix path_converter() function).

• bpo-25400: RobotFileParser now correctly returns default values for crawl_delay and request_rate. Initial patch by Peter Wirtz.

• bpo-27932: Prevent memory leak in win32_ver().

• Fix UnboundLocalError in socket._sendfile_use_sendfile.

• bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation of os.stat(). Patch by Eryk Sun.

• bpo-22493: Warning message emitted by using inline flags in the middle of regular expression now contains a (truncated) regex pattern. Patch by Tim Graham.

• bpo-25270: Prevent codecs.escape_encode() from raising SystemError when an empty bytestring is passed.

• bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

• bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch by Gergely Imreh and Markus Holtermann.

• bpo-28114: Fix a crash in parse_envlist() when env contains byte strings. Patch by Eryk Sun.

• bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and binascii.a2b_qp().

• bpo-27906: Fix socket accept exhaustion during high TCP traffic. Patch by Kevin Conway.

• bpo-28174: Handle when SO_REUSEPORT isn’t properly supported. Patch by Seth Michael Larson.

• bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__. Patch by iceboy.

• bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

• bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

• bpo-27759: Fix selectors incorrectly retain invalid file descriptors. Patch by Mark Williams.

• bpo-28325: Remove vestigial MacOS 9 macurl2path module and its tests.

• bpo-28368: Refuse monitoring processes if the child watcher has no loop attached. Patch by Vincent Michel.

• bpo-28369: Raise RuntimeError when transport’s FD is used with add_reader, add_writer, etc.

• bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by Коренберг Марк.

• bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

• bpo-28372: Fix asyncio to support formatting of non-python coroutines.

• bpo-28399: Remove UNIX socket from FS before binding. Patch by Коренберг Марк.

• bpo-27972: Prohibit Tasks to await on themselves.

• bpo-24142: Reading a corrupt config file left configparser in an invalid state. Original patch by Florian Höch.

• bpo-29581: ABCMeta.__new__ now accepts **kwargs, allowing abstract base classes to use keyword parameters in __init_subclass__. Patch by Nate Soares.

• bpo-25532: inspect.unwrap() will now only try to unwrap an object sys.getrecursionlimit() times, to protect against objects which create a new object on every attribute access.

• bpo-30177: path.resolve(strict=False) no longer cuts the path after the first element not present in the filesystem. Patch by Antoine Pietri.

Documentation

• bpo-31294: Fix incomplete code snippet in the ZeroMQSocketListener and ZeroMQSocketHandler examples and adapt them to Python 3.

• bpo-21649: Add RFC 7525 and Mozilla server side TLS links to SSL documentation.

• bpo-31128: Allow the pydoc server to bind to arbitrary hostnames.

• bpo-30803: Clarify doc on truth value testing. Original patch by Peter Thomassen.

• bpo-30176: Add missing attribute related constants in curses documentation.

• bpo-30052: the link targets for bytes() and bytearray() are now their respective type definitions, rather than the corresponding builtin function entries. Use bytes and bytearray to reference the latter.

  In order to ensure this and future cross-reference updates are applied automatically, the daily documentation builds now disable the default output caching features in Sphinx.

• bpo-26985: Add missing info of code object in inspect documentation.

• bpo-19824: Improve the documentation for, and links to, template strings by emphasizing their utility for internationalization, and by clarifying some usage constraints. (See also: bpo-20314, bpo-12518)

• bpo-28929: Link the documentation to its source file on GitHub.

• bpo-25008: Document smtpd.py as effectively deprecated and add a pointer to aiosmtpd, a third-party asyncio-based replacement.

• bpo-26355: Add canonical header link on each page to corresponding major version of the documentation. Patch by Matthias Bussonnier.

• bpo-29349: Fix Python 2 syntax in code for building the documentation.

• bpo-23722: The data model reference and the porting section in the 3.6 What’s New guide now cover the additional __classcell__ handling needed for custom metaclasses to fully support PEP 487 and zero-argument super().

• bpo-28513: Documented command-line interface of zipfile.

Tests

• bpo-29639: test.support.HOST is now “localhost”, a new HOSTv4 constant has been added for your 127.0.0.1 needs, similar to the existing HOSTv6 constant.

• bpo-31320: Silence traceback in test_ssl

• bpo-31346: Prefer PROTOCOL_TLS_CLIENT and PROTOCOL_TLS_SERVER protocols for SSLContext.

• bpo-25674: Remove sha256.tbs-internet.com ssl test

• bpo-30715: Address ALPN callback changes for OpenSSL 1.1.0f. The latest version behaves like OpenSSL 1.0.2 and no longer aborts handshake.

• bpo-30822: regrtest: Exclude tzdata from regrtest –all. When running the test suite using –use=all / -u all, exclude tzdata since it makes test_datetime too slow (15-20 min on some buildbots) which then times out on some buildbots. Fix also regrtest command line parser to allow passing -u extralargefile to run test_zipfile64.

• bpo-30695: Add the set_nomemory(start, stop) and remove_mem_hooks() functions to the _testcapi module.

• bpo-30357: test_thread: setUp() now uses support.threading_setup() and support.threading_cleanup() to wait until threads complete to avoid random side effects on following tests. Initial patch written by Grzegorz Grzywacz.

• bpo-30197: Enhanced functions swap_attr() and swap_item() in the test.support module. They now work when delete replaced attribute or item inside the with statement. The old value of the attribute or item (or None if it doesn’t exist) now will be assigned to the target of the “as” clause, if there is one.

• bpo-24932: Use proper command line parsing in _testembed

• bpo-28950: Disallow -j0 to be combined with -T/-l in regrtest command line arguments.

• bpo-28683: Fix the tests that bind() a unix socket and raise PermissionError on Android for a non-root user.

• bpo-26936: Fix the test_socket failures on Android - getservbyname(), getservbyport() and getaddrinfo() are broken on some Android API levels.

• bpo-28666: Now test.support.rmtree is able to remove unwritable or unreadable directories.

• bpo-23839: Various caches now are cleared before running every test file.

• bpo-26944: Fix test_posix for Android where ‘id -G’ is entirely wrong or missing the effective gid.

• bpo-28409: regrtest: fix the parser of command line arguments.

• bpo-28217: Adds _testconsole module to test console input.

• bpo-26939: Add the support.setswitchinterval() function to fix test_functools hanging on the Android armv7 qemu emulator.

Build

• bpo-31354: Allow –with-lto to be used on all builds, not just make profile-opt.

• bpo-31370: Remove support for building –without-threads.

  This option is not really useful anymore in the 21st century. Removing lots of conditional paths allows us to simplify the code base, including in difficult to maintain low-level internal code.

• bpo-31341: Per PEP 11, support for the IRIX operating system was removed.

• bpo-30854: Fix compile error when compiling –without-threads. Patch by Masayuki Yamamoto.

• bpo-30687: Locate msbuild.exe on Windows when building rather than vcvarsall.bat

• bpo-20210: Support the disabled marker in Setup files. Extension modules listed after this marker are not built at all, neither by the Makefile nor by setup.py.

• bpo-29941: Add --with-assertions configure flag to explicitly enable C assert() checks. Defaults to off. --with-pydebug implies --with-assertions.

• bpo-28787: Fix out-of-tree builds of Python when configured with --with--dtrace.

• bpo-29243: Prevent unnecessary rebuilding of Python during make test, make install and some other make targets when configured with --enable-optimizations.

• bpo-23404: Don’t regenerate generated files based on file modification time anymore: the action is now explicit. Replace make touch with make regen-all.

• bpo-29643: Fix --enable-optimization didn’t work.

• bpo-27593: sys.version and the platform module python_build(), python_branch(), and python_revision() functions now use git information rather than hg when building from a repo.

• bpo-29572: Update Windows build and OS X installers to use OpenSSL 1.0.2k.

• bpo-27659: Prohibit implicit C function declarations: use -Werror=implicit-function-declaration when possible (GCC and Clang, but it depends on the compiler version). Patch written by Chi Hsuan Yen.

• bpo-29384: Remove old Be OS helper scripts.

• bpo-26851: Set Android compilation and link flags.

• bpo-28768: Fix implicit declaration of function _setmode. Patch by Masayuki Yamamoto

• bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

• bpo-23903: Added missed names to PC/python3.def.

• bpo-28762: lockf() is available on Android API level 24, but the F_LOCK macro is not defined in android-ndk-r13.

• bpo-28538: Fix the compilation error that occurs because if_nameindex() is available on Android API level 24, but the if_nameindex structure is not defined.

• bpo-20211: Do not add the directory for installing C header files and the directory for installing object code libraries to the cross compilation search paths. Original patch by Thomas Petazzoni.

• bpo-28849: Do not define sys.implementation._multiarch on Android.

• bpo-10656: Fix out-of-tree building on AIX. Patch by Tristan Carel and Michael Haubenwallner.

• bpo-26359: Rename –with-optimiations to –enable-optimizations.

• bpo-28444: Fix missing extensions modules when cross compiling.

• bpo-28208: Update Windows build and OS X installers to use SQLite 3.14.2.

• bpo-28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.

• bpo-21124: Fix building the _struct module on Cygwin by passing NULL instead of &PyType_Type to PyVarObject_HEAD_INIT. Patch by Masayuki Yamamoto.

• bpo-13756: Fix building extensions modules on Cygwin. Patch by Roumen Petrov, based on original patch by Jason Tishler.

• bpo-21085: Add configure check for siginfo_t.si_band, which Cygwin does not provide. Patch by Masayuki Yamamoto with review and rebase by Erik Bray.

• bpo-28258: Fixed build with Estonian locale (python-config and distclean targets in Makefile). Patch by Arfrever Frehtes Taifersar Arahesis.

• bpo-26661: setup.py now detects system libffi with multiarch wrapper.

• bpo-27979: A full copy of libffi is no longer bundled for use when building _ctypes on non-OSX UNIX platforms. An installed copy of libffi is now required when building _ctypes on such platforms.

• bpo-15819: Remove redundant include search directory option for building outside the source tree.

• bpo-28676: Prevent missing ‘getentropy’ declaration warning on macOS. Patch by Gareth Rees.

Windows

• bpo-31392: Update Windows build to use OpenSSL 1.1.0f

• bpo-30389: Adds detection of Visual Studio 2017 to distutils on Windows.

• bpo-31358: zlib is no longer bundled in the CPython source, instead it is downloaded on demand just like bz2, lzma, OpenSSL, Tcl/Tk, and SQLite.

• bpo-31340: Change to building with MSVC v141 (included with Visual Studio 2017)

• bpo-30581: os.cpu_count() now returns the correct number of processors on Windows when the number of logical processors is greater than 64.

• bpo-30916: Pre-build OpenSSL, Tcl and Tk and include the binaries in the build.

• bpo-30731: Add a missing xmlns to python.manifest so that it matches the schema.

• bpo-30291: Allow requiring 64-bit interpreters from py.exe using -64 suffix. Contributed by Steve (Gadget) Barnes.

• bpo-30362: Adds list options (-0, -0p) to py.exe launcher. Contributed by Steve Barnes.

• bpo-23451: Fix socket deprecation warnings in socketmodule.c. Patch by Segev Finer.

• bpo-30450: The build process on Windows no longer depends on Subversion, instead pulling external code from GitHub via a Python script. If Python 3.6 is not found on the system (via py -3.6), NuGet is used to download a copy of 32-bit Python.

• bpo-29579: Removes readme.txt from the installer.

• bpo-25778: winreg does not truncate string correctly (Patch by Eryk Sun)

• bpo-28896: Deprecate WindowsRegistryFinder and disable it by default

• bpo-28522: Fixes mishandled buffer reallocation in getpathp.c

• bpo-28402: Adds signed catalog files for stdlib on Windows.

• bpo-28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch by Eryk Sun)

• bpo-28251: Improvements to help manuals on Windows.

• bpo-28110: launcher.msi has different product codes between 32-bit and 64-bit

• bpo-28161: Opening CON for write access fails

• bpo-28162: WindowsConsoleIO readall() fails if first line starts with Ctrl+Z

• bpo-28163: WindowsConsoleIO fileno() passes wrong flags to _open_osfhandle

• bpo-28164: _PyIO_get_console_type fails for various paths

• bpo-28137: Renames Windows path file to ._pth

• bpo-28138: Windows ._pth file should allow import site

IDLE

• bpo-31493: IDLE code context – fix code update and font update timers.

  Canceling timers prevents a warning message when test_idle completes.

• bpo-31488: IDLE - Update non-key options in former extension classes. When applying configdialog changes, call .reload for each feature class. Change ParenMatch so updated options affect existing instances attached to existing editor windows.

• bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing whitespace strips more than blank spaces. Multiline string literals are not skipped.

• bpo-31480: IDLE - make tests pass with zzdummy extension disabled by default.

• bpo-31421: Document how IDLE runs tkinter programs. IDLE calls tcl/tk update in the background in order to make live

  interaction and experimentation with tkinter applications much easier.

• bpo-31414: IDLE – fix tk entry box tests by deleting first. Adding to an int entry is not the same as deleting and inserting because int(‘’) will fail.

• bpo-31051: Rearrange IDLE configdialog GenPage into Window, Editor, and Help sections.

• bpo-30617: IDLE - Add docstrings and tests for outwin subclass of editor.

  Move some data and functions from the class to module level. Patch by Cheryl Sabella.

• bpo-31287: IDLE - Do not modify tkinter.message in test_configdialog.

• bpo-27099: Convert IDLE’s built-in ‘extensions’ to regular features.

  About 10 IDLE features were implemented as supposedly optional extensions. Their different behavior could be confusing or worse for users and not good for maintenance. Hence the conversion.

  The main difference for users is that user configurable key bindings for builtin features are now handled uniformly. Now, editing a binding in a keyset only affects its value in the keyset. All bindings are defined together in the system-specific default keysets in config-extensions.def. All custom keysets are saved as a whole in config-extension.cfg. All take effect as soon as one clicks Apply or Ok.

  The affected events are ‘<<force-open-completions>>’, ‘<<expand-word>>’, ‘<<force-open-calltip>>’, ‘<<flash-paren>>’, ‘<<format-paragraph>>’, ‘<<run-module>>’, ‘<<check-module>>’, and ‘<<zoom-height>>’. Any (global) customizations made before 3.6.3 will not affect their keyset-specific customization after 3.6.3. and vice versa.

  Initial patch by Charles Wohlganger.

• bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog. Patch by Cheryl Sabella.

• bpo-31001: Add tests for configdialog highlight tab. Patch by Cheryl Sabella.

• bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog. The slightly modified tests continue to pass. Patch by Cheryl Sabella.

• bpo-31130: IDLE – stop leaks in test_configdialog. Initial patch by Victor Stinner.

• bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl Sabella.

• bpo-19903: IDLE: Calltips use inspect.signature instead of inspect.getfullargspec. This improves calltips for builtins converted to use Argument Clinic. Patch by Louie Lu.

• bpo-31083: IDLE - Add an outline of a TabPage class in configdialog. Update existing classes to match outline. Initial patch by Cheryl Sabella.

• bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The slightly modified tests continue to pass. Patch by Cheryl Sabella.

• bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog.

  Slightly modified tests continue to pass. Fix General tests. Patch mostly by Cheryl Sabella.

• bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry Jan Reedy and Cheryl Sabella.

• bpo-31060: IDLE - Finish rearranging methods of ConfigDialog Grouping methods pertaining to each tab and the buttons will aid writing tests and improving the tabs and will enable splitting the groups into classes.

• bpo-30853: IDLE – Factor a VarTrace class out of ConfigDialog.

  Instance tracers manages pairs consisting of a tk variable and a callback function. When tracing is turned on, setting the variable calls the function. Test coverage for the new class is 100%.

• bpo-31003: IDLE: Add more tests for General tab.

• bpo-30993: IDLE - Improve configdialog font page and tests.

  In configdialog: Document causal pathways in create_font_tab docstring. Simplify some attribute names. Move set_samples calls to var_changed_font (idea from Cheryl Sabella). Move related functions to positions after the create widgets function.

  In test_configdialog: Fix test_font_set so not order dependent. Fix renamed test_indent_scale so it tests the widget. Adjust tests for movement of set_samples call. Add tests for load functions. Put all font tests in one class and tab indent tests in another. Except for two lines, these tests completely cover the related functions.

• bpo-30981: IDLE – Add more configdialog font page tests.

• bpo-28523: IDLE: replace ‘colour’ with ‘color’ in configdialog.

• bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage from 46% to 96%. Patch by Louie Lu.

• bpo-30934: Document coverage details for idlelib tests.

  • Add section to idlelib/idle-test/README.txt.

  • Include check that branches are taken both ways.

  • Exclude IDLE-specific code that does not run during unit tests.

• bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets in docstrings This will facilitate improving the dialog and splitting up the class. Original patch by Cheryl Sabella.

• bpo-30899: IDLE: Add tests for ConfigParser subclasses in config. Patch by Louie Lu.

• bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl Sabella.

• bpo-30851: IDLE: Remove unused variables in configdialog. One is a duplicate, one is set but cannot be altered by users. Patch by Cheryl Sabella.

• bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys as well as mouse. Initial patch by Louie Lu.

• bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

• bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put in config; test. * In config, put dump test code in a function; run it and unittest in ‘if __name__ == ‘__main__’. * Add class config.ConfigChanges based on changes_class_v4.py on bpo issue. * Add class test_config.ChangesTest, partly using configdialog_tests_v1.py. * Revise configdialog to use ConfigChanges; see tracker msg297804. * Revise test_configdialog to match configdialog changes. * Remove configdialog functions unused or moved to ConfigChanges. Cheryl Sabella contributed parts of the patch.

• bpo-30777: IDLE: configdialog - Add docstrings and fix comments. Patch by Cheryl Sabella.

• bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and more tests. Patch by Cheryl Sabella.

• bpo-30723: IDLE: Make several improvements to parenmatch. Add ‘parens’ style to highlight both opener and closer. Make ‘default’ style, which is not default, a synonym for ‘opener’. Make time-delay work the same with all styles. Add help for config dialog extensions tab, including help for parenmatch. Add new tests. Original patch by Charles Wohlganger.

• bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl Sabella

• bpo-21519: IDLE’s basic custom key entry dialog now detects duplicates properly. Original patch by Saimadhav Heblikar.

• bpo-29910: IDLE no longer deletes a character after commenting out a region by a key shortcut. Add return 'break' for this and other potential conflicts between IDLE and default key bindings.

• bpo-30728: Review and change idlelib.configdialog names. Lowercase method and attribute names. Replace ‘colour’ with ‘color’, expand overly cryptic names, delete unneeded underscores. Replace import * with specific imports. Patches by Cheryl Sabella.

• bpo-6739: IDLE: Verify user-entered key sequences by trying to bind them with tk. Add tests for all 3 validation functions. Original patch by G Polo. Tests added by Cheryl Sabella.

• bpo-15786: Fix several problems with IDLE’s autocompletion box. The following should now work: clicking on selection box items; using the scrollbar; selecting an item by hitting Return. Hangs on MacOSX should no longer happen. Patch by Louie Lu.

• bpo-25514: Add doc subsubsection about IDLE failure to start. Popup no-connection message directs users to this section.

• bpo-30642: Fix reference leaks in IDLE tests. Patches by Louie Lu and Terry Jan Reedy.

• bpo-30495: Add docstrings for textview.py and use PEP8 names. Patches by Cheryl Sabella and Terry Jan Reedy.

• bpo-30290: Help-about: use pep8 names and add tests. Increase coverage to 100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan Reedy.

• bpo-30303: Add _utest option to textview; add new tests. Increase coverage to 100%. Patches by Louie Lu and Terry Jan Reedy.

• bpo-29071: IDLE colors f-string prefixes (but not invalid ur prefixes).

• bpo-28572: Add 10% to coverage of IDLE’s test_configdialog. Update and augment description of the configuration system.

Tools/Demos

• bpo-30983: gdb integration commands (py-bt, etc.) work on optimized shared builds now, too. PEP 523 introduced _PyEval_EvalFrameDefault which inlines PyEval_EvalFrameEx on non-debug shared builds. This broke the ability to use py-bt, py-up, and a few other Python-specific gdb integrations. The problem is fixed by only looking for _PyEval_EvalFrameDefault frames in python-gdb.py. Original patch by Bruno “Polaco” Penteado.

• bpo-29748: Added the slice index converter in Argument Clinic.

• bpo-24037: Argument Clinic now uses the converter bool(accept={int}) rather than int for semantical booleans. This avoids repeating the default value for Python and C and will help in converting to bool in future.

• bpo-29367: python-gdb.py now supports also method-wrapper (wrapperobject) objects.

• bpo-28023: Fix python-gdb.py didn’t support new dict implementation.

• bpo-15369: The pybench and pystone microbenchmark have been removed from Tools. Please use the new Python benchmark suite https://github.com/python/performance which is more reliable and includes a portable version of pybench working on Python 2 and Python 3.

• bpo-28102: The zipfile module CLI now prints usage to stderr. Patch by Stephen J. Turnbull.

C API

• bpo-31338: Added the Py_UNREACHABLE() macro for code paths which are never expected to be reached. This and a few other useful macros are now documented in the C API manual.

• bpo-30832: Remove own implementation for thread-local storage.

  CPython has provided the own implementation for thread-local storage (TLS) on Python/thread.c, it’s used in the case which a platform has not supplied native TLS. However, currently all supported platforms (Windows and pthreads) have provided native TLS and defined the Py_HAVE_NATIVE_TLS macro with unconditional in any case.

• bpo-30708: PyUnicode_AsWideCharString() now raises a ValueError if the second argument is NULL and the wchar_t* string contains null characters.

• bpo-16500: Deprecate PyOS_AfterFork() and add PyOS_BeforeFork(), PyOS_AfterFork_Parent() and PyOS_AfterFork_Child().

• bpo-6532: The type of results of PyThread_start_new_thread() and PyThread_get_thread_ident(), and the id parameter of PyThreadState_SetAsyncExc() changed from “long” to “unsigned long”.

• bpo-27867: Function PySlice_GetIndicesEx() is deprecated and replaced with a macro if Py_LIMITED_API is not set or set to the value between 0x03050400 and 0x03060000 (not including) or 0x03060100 or higher. Added functions PySlice_Unpack() and PySlice_AdjustIndices().

• bpo-29083: Fixed the declaration of some public API functions. PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not available in limited API. PyArg_ValidateKeywordArguments(), PyArg_UnpackTuple() and Py_BuildValue() were not available in limited API of version < 3.3 when PY_SSIZE_T_CLEAN is defined.

• bpo-28769: The result of PyUnicode_AsUTF8AndSize() and PyUnicode_AsUTF8() is now of type const char * rather of char *.

• bpo-29058: All stable API extensions added after Python 3.2 are now available only when Py_LIMITED_API is set to the PY_VERSION_HEX value of the minimum Python version supporting this API.

• bpo-28822: The index parameters start and end of PyUnicode_FindChar() are now adjusted to behave like str[start:end].

• bpo-28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.

• bpo-28761: The fields name and doc of structures PyMemberDef, PyGetSetDef, PyStructSequence_Field, PyStructSequence_Desc, and wrapperbase are now of type const char * rather of char *.

• bpo-28748: Private variable _Py_PackageContext is now of type const char * rather of char *.

• bpo-19569: Compiler warnings are now emitted if use most of deprecated functions.

• bpo-28426: Deprecated undocumented functions PyUnicode_AsEncodedObject(), PyUnicode_AsDecodedObject(), PyUnicode_AsDecodedUnicode() and PyUnicode_AsEncodedUnicode().

Python 3.6.6 final

Release date: 2018-06-27

There were no new changes in version 3.6.6.

Python 3.6.6 release candidate 1

Release date: 2018-06-11

Core and Builtins

• bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() correctly

• bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on interpreter shutdown even when there was a custom handler set previously. Patch by Philipp Kerling.

• bpo-33622: Fixed a leak when the garbage collector fails to add an object with the __del__ method or referenced by it into the gc.garbage list. PyGC_Collect() can now be called when an exception is set and preserves it.

• bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

• bpo-33391: Fix a leak in set_symmetric_difference().

• bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike Beer.

• bpo-33231: Fix potential memory leak in normalizestring().

• bpo-29922: Improved error messages in ‘async with’ when __aenter__() or __aexit__() return non-awaitable object.

• bpo-33199: Fix ma_version_tag in dict implementation is uninitialized when copying from key-sharing dict.

• bpo-33041: Fixed jumping when the function contains an async for loop.

• bpo-32282: Fix an unnecessary ifdef in the include of VersionHelpers.h in socketmodule on Windows.

• bpo-21983: Fix a crash in ctypes.cast() in case the type argument is a ctypes structured data type. Patch by Eryk Sun and Oren Milman.

Library

• bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set. Patch by Steve Weber.

• bpo-33812: Datetime instance d with non-None tzinfo, but with d.tzinfo.utcoffset(d) returning None is now treated as naive by the astimezone() method.

• bpo-30805: Avoid race condition with debug logging

• bpo-33767: The concatenation (+) and repetition (*) sequence operations now raise TypeError instead of SystemError when performed on mmap.mmap objects. Patch by Zackery Spytz.

• bpo-32684: Fix gather to propagate cancellation of itself even with return_exceptions.

• bpo-33674: Fix a race condition in SSLProtocol.connection_made() of asyncio.sslproto: start immediately the handshake instead of using call_soon(). Previously, data_received() could be called before the handshake started, causing the handshake to hang or fail.

• bpo-31647: Fixed bug where calling write_eof() on a _SelectorSocketTransport after it’s already closed raises AttributeError.

• bpo-33672: Fix Task.__repr__ crash with Cython’s bogus coroutines

• bpo-33469: Fix RuntimeError after closing loop that used run_in_executor

• bpo-11874: Use a better regex when breaking usage into wrappable parts. Avoids bogus assertion errors from custom metavar strings.

• bpo-30877: Fixed a bug in the Python implementation of the JSON decoder that prevented the cache of parsed strings from clearing after finishing the decoding. Based on patch by c-fos.

• bpo-33548: tempfile._candidate_tempdir_list should consider common TEMP locations

• bpo-33542: Prevent uuid.get_node from using a DUID instead of a MAC on Windows. Patch by Zvi Effron

• bpo-26819: Fix race condition with ReadTransport.resume_reading in Windows proactor event loop.

• bpo-28556: Minor fixes in typing module: add annotations to NamedTuple.__new__, pass *args and **kwds in Generic.__new__. Original PRs by Paulius Šarka and Chad Dombrova.

• bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

• bpo-33422: Fix trailing quotation marks getting deleted when looking up byte/string literals on pydoc. Patch by Andrés Delfino.

• bpo-33197: Update error message when constructing invalid inspect.Parameters Patch by Dong-hee Na.

• bpo-33383: Fixed crash in the get() method of the dbm.ndbm database object when it is called with a single argument.

• bpo-33329: Fix multiprocessing regression on newer glibcs

• bpo-991266: Fix quoting of the Comment attribute of http.cookies.SimpleCookie.

• bpo-33131: Upgrade bundled version of pip to 10.0.1.

• bpo-33308: Fixed a crash in the parser module when converting an ST object to a tree of tuples or lists with line_info=False and col_info=True.

• bpo-33263: Fix FD leak in _SelectorSocketTransport Patch by Vlad Starostin.

• bpo-33256: Fix display of <module> call in the html produced by cgitb.html(). Patch by Stéphane Blondon.

• bpo-33203: random.Random.choice() now raises IndexError for empty sequences consistently even when called from subclasses without a getrandbits() implementation.

• bpo-33224: Update difflib.mdiff() for PEP 479. Convert an uncaught StopIteration in a generator into a return-statement.

• bpo-33209: End framing at the end of C implementation of pickle.Pickler.dump().

• bpo-32861: The urllib.robotparser’s __str__ representation now includes wildcard entries and the “Crawl-delay” and “Request-rate” fields. Patch by Michael Lazar.

• bpo-33096: Allow ttk.Treeview.insert to insert iid that has a false boolean value. Note iid=0 and iid=False would be same. Patch by Garvit Khatri.

• bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

• bpo-33021: Release the GIL during fstat() calls, avoiding hang of all threads when calling mmap.mmap(), os.urandom(), and random.seed(). Patch by Nir Soffer.

• bpo-27683: Fix a regression in ipaddress that result of hosts() is empty when the network is constructed by a tuple containing an integer mask and only 1 bit left for addresses.

• bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to stderr in subprocess if another low descriptor is closed.

• bpo-31908: Fix output of cover files for trace module command-line tool. Previously emitted cover files only when --missing option was used. Patch by Michael Selik.

• bpo-31457: If nested log adapters are used, the inner process() methods are no longer omitted.

• bpo-16865: Support arrays >=2GiB in ctypes. Patch by Segev Finer.

• bpo-31238: pydoc: the stop() method of the private ServerThread class now waits until DocServer.serve_until_quit() completes and then explicitly sets its docserver attribute to None to break a reference cycle.

Documentation

• bpo-33503: Fix broken pypi link

• bpo-33421: Add missing documentation for typing.AsyncContextManager.

• bpo-33378: Add Korean language switcher for https://docs.python.org/3/

• bpo-33276: Clarify that the __path__ attribute on modules cannot be just any value.

• bpo-33201: Modernize documentation for writing C extension types.

• bpo-33195: Deprecate Py_UNICODE usage in c-api/arg document. Py_UNICODE related APIs are deprecated since Python 3.3, but it is missed in the document.

• bpo-33126: Document PyBuffer_ToContiguous().

• bpo-27212: Modify documentation for the islice() recipe to consume initial values up to the start index.

• bpo-28247: Update zipapp documentation to describe how to make standalone applications.

• bpo-18802: Documentation changes for ipaddress. Patch by Jon Foster and Berker Peksag.

• bpo-27428: Update documentation to clarify that WindowsRegistryFinder implements MetaPathFinder. (Patch by Himanshu Lakhara)

• bpo-8243: Add a note about curses.addch and curses.addstr exception behavior when writing outside a window, or pad.

• bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and CERT_REQUIRED flags for ssl.SSLContext.verify_mode.

Tests

• bpo-33655: Ignore test_posix_fallocate failures on BSD platforms that might be due to running on ZFS.

• bpo-19417: Add test_bdb.py.

Build

• bpo-5755: Move -Wstrict-prototypes option to CFLAGS_NODIST from OPT. This option emitted annoying warnings when building extension modules written in C++.

• bpo-33614: Ensures module definition files for the stable ABI on Windows are correctly regenerated.

• bpo-33522: Enable CI builds on Visual Studio Team Services at https://python.visualstudio.com/cpython

• bpo-33012: Add -Wno-cast-function-type for gcc 8 for silencing warnings about function casts like casting to PyCFunction in method definition lists.

• bpo-33394: Enable the verbose build for extension modules, when GNU make is passed macros on the command line.

Windows

• bpo-33184: Update Windows installer to OpenSSL 1.0.2o.

macOS

• bpo-33184: Update macOS installer build to use OpenSSL 1.0.2o.

IDLE

• bpo-33656: On Windows, add API call saying that tk scales for DPI. On Windows 8.1+ or 10, with DPI compatibility properties of the Python binary unchanged, and a monitor resolution greater than 96 DPI, this should make text and lines sharper. It should otherwise have no effect.

• bpo-33768: Clicking on a context line moves that line to the top of the editor window.

• bpo-33763: IDLE: Use read-only text widget for code context instead of label widget.

• bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse wheel and scrollbar slider moved text by a fixed number of pixels, resulting in partial lines at the top of the editor box. The change also applies to the shell and grep output windows, but not to read-only text views.

• bpo-33679: Enable theme-specific color configuration for Code Context. Use the Highlights tab to see the setting for built-in themes or add settings to custom themes.

• bpo-33642: Display up to maxlines non-blank lines for Code Context. If there is no current context, show a single blank line.

• bpo-33628: IDLE: Cleanup codecontext.py and its test.

• bpo-33564: IDLE’s code context now recognizes async as a block opener.

• bpo-29706: IDLE now colors async and await as keywords in 3.6. They become full keywords in 3.7.

• bpo-21474: Update word/identifier definition from ascii to unicode. In text and entry boxes, this affects selection by double-click, movement left/right by control-left/right, and deletion left/right by control-BACKSPACE/DEL.

• bpo-33204: IDLE: consistently color invalid string prefixes. A ‘u’ string prefix cannot be paired with either ‘r’ or ‘f’. Consistently color as much of the prefix, starting at the right, as is valid. Revise and extend colorizer test.

• bpo-32831: Add docstrings and tests for codecontext.

Tools/Demos

• bpo-33189: pygettext.py now recognizes only literal strings as docstrings and translatable strings, and rejects bytes literals and f-string expressions.

• bpo-31920: Fixed handling directories as arguments in the pygettext script. Based on patch by Oleg Krasnikov.

• bpo-29673: Fix pystackv and pystack gdbinit macros.

• bpo-32885: Add an -n flag for Tools/scripts/pathfix.py to disable automatic backup creation (files with ~ suffix).

• bpo-31583: Fix 2to3 for using with –add-suffix option but without –output-dir option for relative path to files in current directory.

C API

• bpo-32374: Document that m_traverse for multi-phase initialized modules can be called with m_state=NULL, and add a sanity check

Python 3.6.5 final

Release date: 2018-03-28

Tests

• bpo-32872: Avoid regrtest compatibility issue with namespace packages.

Build

• bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.

Python 3.6.5 release candidate 1

Release date: 2018-03-13

Security

• bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on Windows

• bpo-32981: Regexes in difflib and poplib were vulnerable to catastrophic backtracking. These regexes formed potential DOS vectors (REDOS). They have been refactored. This resolves CVE-2018-1060 and CVE-2018-1061. Patch by Jamie Davis.

Core and Builtins

• bpo-33026: Fixed jumping out of “with” block by setting f_lineno.

• bpo-17288: Prevent jumps from ‘return’ and ‘exception’ trace events.

• bpo-32889: Update Valgrind suppression list to account for the rename of Py_ADDRESS_IN_RANG to address_in_range.

• bpo-32650: Pdb and other debuggers dependent on bdb.py will correctly step over (next command) native coroutines. Patch by Pablo Galindo.

• bpo-32685: Improve suggestion when the Python 2 form of print statement is either present on the same line as the header of a compound statement or else terminated by a semi-colon instead of a newline. Patch by Nitish Chandra.

• bpo-32583: Fix possible crashing in builtin Unicode decoders caused by write out-of-bound errors when using customized decode error handlers.

• bpo-26163: Improved frozenset() hash to create more distinct hash values when faced with datasets containing many similar values.

• bpo-27169: The __debug__ constant is now optimized out at compile time. This fixes also bpo-22091.

• bpo-32329: sys.flags.hash_randomization is now properly set to 0 when hash randomization is turned off by PYTHONHASHSEED=0.

• bpo-30416: The optimizer is now protected from spending much time doing complex calculations and consuming much memory for creating large constants in constant folding.

• bpo-18533: repr() on a dict containing its own values() or items() no longer raises RecursionError; OrderedDict similarly. Instead, use ..., as for other recursive structures. Patch by Ben North.

• bpo-32028: Leading whitespace is now correctly ignored when generating suggestions for converting Py2 print statements to Py3 builtin print function calls. Patch by Sanyam Khurana.

• bpo-32137: The repr of deeply nested dict now raises a RecursionError instead of crashing due to a stack overflow.

Library

• bpo-33064: lib2to3 now properly supports trailing commas after *args and **kwargs in function signatures.

• bpo-31804: Avoid failing in multiprocessing.Process if the standard streams are closed or None at exit.

• bpo-33037: Skip sending/receiving data after SSL transport closing.

• bpo-30353: Fix ctypes pass-by-value for structs on 64-bit Cygwin/MinGW.

• bpo-33009: Fix inspect.signature() for single-parameter partialmethods.

• bpo-32969: Expose several missing constants in zlib and fix corresponding documentation.

• bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values. Patch by Joffrey Fuhrer.

• bpo-30622: The ssl module now detects missing NPN support in LibreSSL.

• bpo-32922: dbm.open() now encodes filename with the filesystem encoding rather than default encoding.

• bpo-32859: In os.dup2, don’t check every call whether the dup3 syscall exists or not.

• bpo-21060: Rewrite confusing message from setup.py upload from “No dist file created in earlier command” to the more helpful “Must create and upload files in one command”.

• bpo-32857: In tkinter, after_cancel(None) now raises a ValueError instead of canceling the first scheduled function. Patch by Cheryl Sabella.

• bpo-32852: Make sure sys.argv remains as a list when running trace.

• bpo-32841: Fixed asyncio.Condition issue which silently ignored cancellation after notifying and cancelling a conditional lock. Patch by Bar Harel.

• bpo-31787: Fixed refleaks of __init__() methods in various modules. (Contributed by Oren Milman)

• bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff() when only the last field is quoted. Patch by Jake Davis.

• bpo-32394: socket: Remove TCP_FASTOPEN, TCP_KEEPCNT flags on older version Windows during run-time.

• bpo-32777: Fix a rare but potential pre-exec child process deadlock in subprocess on POSIX systems when marking file descriptors inheritable on exec in the child process. This bug appears to have been introduced in 3.4.

• bpo-32647: The ctypes module used to depend on indirect linking for dlopen. The shared extension is now explicitly linked against libdl on platforms with dl.

• bpo-32734: Fixed asyncio.Lock() safety issue which allowed acquiring and locking the same lock multiple times, without it being free. Patch by Bar Harel.

• bpo-32727: Do not include name field in SMTP envelope from address. Patch by Stéphane Wirtel

• bpo-27931: Fix email address header parsing error when the username is an empty quoted string. Patch by Xiang Zhang.

• bpo-32304: distutils’ upload command no longer corrupts tar files ending with a CR byte, and no longer tries to convert CR to CRLF in any of the upload text fields.

• bpo-32502: uuid.uuid1 no longer raises an exception if a 64-bit hardware address is encountered.

• bpo-31848: Fix the error handling in Aifc_read.initfp() when the SSND chunk is not found. Patch by Zackery Spytz.

• bpo-32555: On FreeBSD and Solaris, os.strerror() now always decode the byte string from the current locale encoding, rather than using ASCII/surrogateescape in some cases.

• bpo-32521: The nis module is now compatible with new libnsl and headers location.

• bpo-32473: Improve ABCMeta._dump_registry() output readability

• bpo-32521: glibc has removed Sun RPC. Use replacement libtirpc headers and library in nis module.

• bpo-32228: Ensure that truncate() preserves the file position (as reported by tell()) after writes longer than the buffer size.

• bpo-26133: Don’t unsubscribe signals in asyncio UNIX event loop on interpreter shutdown.

• bpo-32185: The SSL module no longer sends IP addresses in SNI TLS extension on platforms with OpenSSL 1.0.2+ or inet_pton.

• bpo-32323: urllib.parse.urlsplit() does not convert zone-id (scope) to lower case for scoped IPv6 addresses in hostnames now.

• bpo-32302: Fix bdist_wininst of distutils for CRT v142: it binary compatible with CRT v140.

• bpo-32255: A single empty field is now always quoted when written into a CSV file. This allows to distinguish an empty row from a row consisting of a single empty field. Patch by Licht Takeuchi.

• bpo-32277: Raise NotImplementedError instead of SystemError on platforms where chmod(..., follow_symlinks=False) is not supported. Patch by Anthony Sottile.

• bpo-32199: The getnode() ip getter now uses ‘ip link’ instead of ‘ip link list’.

• bpo-27456: Ensure TCP_NODELAY is set on Linux. Tests by Victor Stinner.

• bpo-31900: The locale.localeconv() function now sets temporarily the LC_CTYPE locale to the LC_NUMERIC locale to decode decimal_point and thousands_sep byte strings if they are non-ASCII or longer than 1 byte, and the LC_NUMERIC locale is different than the LC_CTYPE locale. This temporary change affects other threads.

  Same change for the str.format() method when formatting a number (int, float, float and subclasses) with the n type (ex: '{:n}'.format(1234)).

• bpo-31802: Importing native path module (posixpath, ntpath) now works even if the os module still is not imported.

Documentation

• bpo-17232: Clarify docs for -O and -OO. Patch by Terry Reedy.

• bpo-32800: Update link to w3c doc for xml default namespaces.

• bpo-8722: Document __getattr__() behavior when property get() method raises AttributeError.

• bpo-32614: Modify RE examples in documentation to use raw strings to prevent DeprecationWarning and add text to REGEX HOWTO to highlight the deprecation.

• bpo-31972: Improve docstrings for pathlib.PurePath subclasses.

• bpo-17799: Explain real behaviour of sys.settrace and sys.setprofile and their C-API counterparts regarding which type of events are received in each function. Patch by Pablo Galindo Salgado.

Tests

• bpo-32517: Fix failing test_asyncio on macOS 10.12.2+ due to transport of KqueueSelector loop was not being closed.

• bpo-32721: Fix test_hashlib to not fail if the _md5 module is not built.

• bpo-32252: Fix faulthandler_suppress_crash_report() used to prevent core dump files when testing crashes. getrlimit() returns zero on success.

• bpo-31518: Debian Unstable has disabled TLS 1.0 and 1.1 for SSLv23_METHOD(). Change TLS/SSL protocol of some tests to PROTOCOL_TLS or PROTOCOL_TLSv1_2 to make them pass on Debian.

Build

• bpo-32635: Fix segfault of the crypt module when libxcrypt is provided instead of libcrypt at the system.

Windows

• bpo-33016: Fix potential use of uninitialized memory in nt._getfinalpathname

• bpo-32903: Fix a memory leak in os.chdir() on Windows if the current directory is set to a UNC path.

• bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

• bpo-32409: Ensures activate.bat can handle Unicode contents.

• bpo-32457: Improves handling of denormalized executable path when launching Python.

• bpo-32370: Use the correct encoding for ipconfig output in the uuid module. Patch by Segev Finer.

• bpo-29248: Fix os.readlink() on Windows, which was mistakenly treating the PrintNameOffset field of the reparse data buffer as a number of characters instead of bytes. Patch by Craig Holmquist and SSE4.

• bpo-32588: Create standalone _distutils_findvs module.

macOS

• bpo-32726: Provide an additional, more modern macOS installer variant that supports macOS 10.9+ systems in 64-bit mode only. Upgrade the supplied third-party libraries to OpenSSL 1.0.2n, XZ 5.2.3, and SQLite 3.22.0. The 10.9+ installer now links with and supplies its own copy of Tcl/Tk 8.6.8.

IDLE

• bpo-32984: Set __file__ while running a startup file. Like Python, IDLE optionally runs one startup file in the Shell window before presenting the first interactive input prompt. For IDLE, -s runs a file named in environmental variable IDLESTARTUP or PYTHONSTARTUP; -r file runs file. Python sets __file__ to the startup file name before running the file and unsets it before the first prompt. IDLE now does the same when run normally, without the -n option.

• bpo-32940: Simplify and rename StringTranslatePseudoMapping in pyparse.

• bpo-32916: Change str to code in pyparse.

• bpo-32905: Remove unused code in pyparse module.

• bpo-32874: Add tests for pyparse.

• bpo-32837: Using the system and place-dependent default encoding for open() is a bad idea for IDLE’s system and location-independent files.

• bpo-32826: Add “encoding=utf-8” to open() in IDLE’s test_help_about. GUI test test_file_buttons() only looks at initial ascii-only lines, but failed on systems where open() defaults to ‘ascii’ because readline() internally reads and decodes far enough ahead to encounter a non-ascii character in CREDITS.txt.

• bpo-32765: Update configdialog General tab docstring to add new widgets to the widget list.

Tools/Demos

• bpo-24960: 2to3 and lib2to3 can now read pickled grammar files using pkgutil.get_data() rather than probing the filesystem. This lets 2to3 and lib2to3 work when run from a zipfile.

• bpo-32222: Fix pygettext not extracting docstrings for functions with type annotated arguments. Patch by Toby Harradine.

C API

• bpo-29084: Undocumented C API for OrderedDict has been excluded from the limited C API. It was added by mistake and actually never worked in the limited C API.

Python 3.6.4 final

Release date: 2017-12-18

There were no new code changes in version 3.6.4 since v3.6.4rc1.

Python 3.6.4 release candidate 1

Release date: 2017-12-05

Core and Builtins

• bpo-32176: co_flags.CO_NOFREE is now always set correctly by the code object constructor based on freevars and cellvars, rather than needing to be set correctly by the caller. This ensures it will be cleared automatically when additional cell references are injected into a modified code object and function.

• bpo-31949: Fixed several issues in printing tracebacks (PyTraceBack_Print()).

  • Setting sys.tracebacklimit to 0 or less now suppresses printing tracebacks.

  • Setting sys.tracebacklimit to None now causes using the default limit.

  • Setting sys.tracebacklimit to an integer larger than LONG_MAX now means using the limit LONG_MAX rather than the default limit.

  • Fixed integer overflows in the case of more than 2**31 traceback items on Windows.

  • Fixed output errors handling.

• bpo-30696: Fix the interactive interpreter looping endlessly when no memory.

• bpo-20047: Bytearray methods partition() and rpartition() now accept only bytes-like objects as separator, as documented. In particular they now raise TypeError rather of returning a bogus result when an integer is passed as a separator.

• bpo-31852: Fix a segmentation fault caused by a combination of the async soft keyword and continuation lines.

• bpo-21720: BytesWarning no longer emitted when the fromlist argument of __import__() or the __all__ attribute of the module contain bytes instances.

• bpo-31825: Fixed OverflowError in the ‘unicode-escape’ codec and in codecs.escape_decode() when decode an escaped non-ascii byte.

• bpo-28603: Print the full context/cause chain of exceptions on interpreter exit, even if an exception in the chain is unhashable or compares equal to later ones. Patch by Zane Bitter.

• bpo-31786: Fix timeout rounding in the select module to round correctly negative timeouts between -1.0 and 0.0. The functions now block waiting for events as expected. Previously, the call was incorrectly non-blocking. Patch by Pablo Galindo.

• bpo-31642: Restored blocking “from package import module” by setting sys.modules[“package.module”] to None.

• bpo-31626: Fixed a bug in debug memory allocator. There was a write to freed memory after shrinking a memory block.

• bpo-31619: Fixed a ValueError when convert a string with large number of underscores to integer with binary base.

• bpo-31592: Fixed an assertion failure in Python parser in case of a bad unicodedata.normalize(). Patch by Oren Milman.

• bpo-31588: Raise a TypeError with a helpful error message when class creation fails due to a metaclass with a bad __prepare__() method. Patch by Oren Milman.

• bpo-31566: Fix an assertion failure in _warnings.warn() in case of a bad __name__ global. Patch by Oren Milman.

• bpo-31505: Fix an assertion failure in json, in case _json.make_encoder() received a bad encoder() argument. Patch by Oren Milman.

• bpo-31492: Fix assertion failures in case of failing to import from a module with a bad __name__ attribute, and in case of failing to access an attribute of such a module. Patch by Oren Milman.

• bpo-31490: Fix an assertion failure in ctypes class definition, in case the class has an attribute whose name is specified in _anonymous_ but not in _fields_. Patch by Oren Milman.

• bpo-31478: Fix an assertion failure in _random.Random.seed() in case the argument has a bad __abs__() method. Patch by Oren Milman.

• bpo-31315: Fix an assertion failure in imp.create_dynamic(), when spec.name is not a string. Patch by Oren Milman.

• bpo-31311: Fix a crash in the __setstate__() method of ctypes._CData, in case of a bad __dict__. Patch by Oren Milman.

• bpo-31293: Fix crashes in true division and multiplication of a timedelta object by a float with a bad as_integer_ratio() method. Patch by Oren Milman.

• bpo-31285: Fix an assertion failure in warnings.warn_explicit, when the return value of the received loader’s get_source() has a bad splitlines() method. Patch by Oren Milman.

• bpo-30817: PyErr_PrintEx() clears now the ignored exception that may be raised by _PySys_SetObjectId(), for example when no memory.

Library

• bpo-28556: Two minor fixes for typing module: allow shallow copying instances of generic classes, improve interaction of __init_subclass__ with generics. Original PRs by Ivan Levkivskyi.

• bpo-27240: The header folding algorithm for the new email policies has been rewritten, which also fixes bpo-30788, bpo-31831, and bpo-32182. In particular, RFC2231 folding is now done correctly.

• bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the GIL when getting the file size. Fixed hang of all threads with inaccessible NFS server. Patch by Nir Soffer.

• bpo-12239: Make msilib.SummaryInformation.GetProperty() return None when the value of property is VT_EMPTY. Initial patch by Mark Mc Mahon.

• bpo-31325: Fix wrong usage of collections.namedtuple() in the RobotFileParser.parse() method.

  Initial patch by Robin Wellner.

• bpo-12382: msilib.OpenDatabase() now raises a better exception message when it couldn’t open or create an MSI file. Initial patch by William Tisäter.

• bpo-32110: codecs.StreamReader.read(n) now returns not more than n characters/bytes for non-negative n. This makes it compatible with read() methods of other file-like objects.

• bpo-32072: Fixed issues with binary plists:

  • Fixed saving bytearrays.

  • Identical objects will be saved only once.

  • Equal references will be load as identical objects.

  • Added support for saving and loading recursive data structures.

• bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunError pickleable.

• bpo-32015: Fixed the looping of asyncio in the case of reconnection the socket during waiting async read/write from/to the socket.

• bpo-32011: Restored support of loading marshal files with the TYPE_INT64 code. These files can be produced in Python 2.7.

• bpo-31970: Reduce performance overhead of asyncio debug mode.

• bpo-9678: Fixed determining the MAC address in the uuid module:

  • Using ifconfig on NetBSD and OpenBSD.

  • Using arp on Linux, FreeBSD, NetBSD and OpenBSD.

  Based on patch by Takayuki Shimizukawa.

• bpo-30057: Fix potential missed signal in signal.signal().

• bpo-31933: Fix Blake2 params leaf_size and node_offset on big endian platforms. Patch by Jack O’Connor.

• bpo-31927: Fixed compilation of the socket module on NetBSD 8. Fixed assertion failure or reading arbitrary data when parse a AF_BLUETOOTH address on NetBSD and DragonFly BSD.

• bpo-27666: Fixed stack corruption in curses.box() and curses.ungetmouse() when the size of types chtype or mmask_t is less than the size of C long. curses.box() now accepts characters as arguments. Based on patch by Steve Fink.

• bpo-31897: plistlib now catches more errors when read binary plists and raises InvalidFileException instead of unexpected exceptions.

• bpo-25720: Fix the method for checking pad state of curses WINDOW. Patch by Masayuki Yamamoto.

• bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD and NetBSD. Fixed the comparison of the kqueue_event objects.

• bpo-31891: Fixed building the curses module on NetBSD.

• bpo-28416: Instances of pickle.Pickler subclass with the persistent_id() method and pickle.Unpickler subclass with the persistent_load() method no longer create reference cycles.

• bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is closed or None.

• bpo-31457: If nested log adapters are used, the inner process() methods are no longer omitted.

• bpo-31457: The manager property on LoggerAdapter objects is now properly settable.

• bpo-31806: Fix timeout rounding in time.sleep(), threading.Lock.acquire() and socket.socket.settimeout() to round correctly negative timeouts between -1.0 and 0.0. The functions now block waiting for events as expected. Previously, the call was incorrectly non-blocking. Patch by Pablo Galindo.

• bpo-28603: traceback: Fix a TypeError that occurred during printing of exception tracebacks when either the current exception or an exception in its context/cause chain is unhashable. Patch by Zane Bitter.

• bpo-30058: Fixed buffer overflow in select.kqueue.control().

• bpo-31770: Prevent a crash when calling the __init__() method of a sqlite3.Cursor object more than once. Patch by Oren Milman.

• bpo-31672: idpattern in string.Template matched some non-ASCII characters. Now it uses -i regular expression local flag to avoid non-ASCII characters.

• bpo-31764: Prevent a crash in sqlite3.Cursor.close() in case the Cursor object is uninitialized. Patch by Oren Milman.

• bpo-31752: Fix possible crash in timedelta constructor called with custom integers.

• bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COM exceptions.

• bpo-31728: Prevent crashes in _elementtree due to unsafe cleanup of Element.text and Element.tail. Patch by Oren Milman.

• bpo-31620: an empty asyncio.Queue now doesn’t leak memory when queue.get pollers timeout

• bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport in asyncio module. This method was previously modifying a wrong reference to the protocol.

• bpo-31675: Fixed memory leaks in Tkinter’s methods splitlist() and split() when pass a string larger than 2 GiB.

• bpo-31673: Fixed typo in the name of Tkinter’s method adderrorinfo().

• bpo-30806: Fix the string representation of a netrc object.

• bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7 and earlier.

• bpo-25351: Avoid venv activate failures with undefined variables

• bpo-25532: inspect.unwrap() will now only try to unwrap an object sys.getrecursionlimit() times, to protect against objects which create a new object on every attribute access.

• bpo-30347: Stop crashes when concurrently iterate over itertools.groupby() iterators.

• bpo-31516: threading.current_thread() should not return a dummy thread at shutdown.

• bpo-31351: python -m ensurepip now exits with non-zero exit code if pip bootstrapping has failed.

• bpo-31482: random.seed() now works with bytes in version=1

• bpo-31334: Fix poll.poll([timeout]) in the select module for arbitrary negative timeouts on all OSes where it can only be a non-negative integer or -1. Patch by Riccardo Coccioli.

• bpo-31310: multiprocessing’s semaphore tracker should be launched again if crashed.

• bpo-31308: Make multiprocessing’s forkserver process immune to Ctrl-C and other user interruptions. If it crashes, restart it when necessary.

Documentation

• bpo-32105: Added asyncio.BaseEventLoop.connect_accepted_socket versionadded marker.

• bpo-31537: Fix incorrect usage of get_history_length in readline documentation example code. Patch by Brad Smith.

• bpo-30085: The operator functions without double underscores are preferred for clarity. The one with underscores are only kept for back-compatibility.

Tests

• bpo-31380: Skip test_httpservers test_undecodable_file on macOS: fails on APFS.

• bpo-31705: Skip test_socket.test_sha256() on Linux kernel older than 4.5. The test fails with ENOKEY on kernel 3.10 (on ppc64le). A fix was merged into the kernel 4.5.

• bpo-31174: Fix test_tools.test_unparse: DirectoryTestCase now stores the names sample to always test the same files. It prevents false alarms when hunting reference leaks.

• bpo-30695: Add the set_nomemory(start, stop) and remove_mem_hooks() functions to the _testcapi module.

Build

• bpo-32059: detect_modules() in setup.py now also searches the sysroot paths when cross-compiling.

• bpo-31957: Fixes Windows SDK version detection when building for Windows.

• bpo-31609: Fixes quotes in PCbuild/clean.bat

• bpo-31934: Abort the build when building out of a not clean source tree.

• bpo-31926: Fixed Argument Clinic sometimes causing compilation errors when there was more than one function and/or method in a .c file with the same name.

• bpo-28791: Update Windows builds to use SQLite 3.21.0.

• bpo-28791: Update OS X installer to use SQLite 3.21.0.

• bpo-22140: Prevent double substitution of prefix in python-config.sh.

• bpo-31536: Avoid wholesale rebuild after make regen-all if nothing changed.

Windows

• bpo-1102: Return None when View.Fetch() returns ERROR_NO_MORE_ITEMS instead of raising MSIError.

  Initial patch by Anthony Tuininga.

• bpo-31944: Fixes Modify button in Apps and Features dialog.

macOS

• bpo-31392: Update macOS installer to use OpenSSL 1.0.2m

IDLE

• bpo-32207: Improve tk event exception tracebacks in IDLE. When tk event handling is driven by IDLE’s run loop, a confusing and distracting queue.EMPTY traceback context is no longer added to tk event exception tracebacks. The traceback is now the same as when event handling is driven by user code. Patch based on a suggestion by Serhiy Storchaka.

• bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of TabbedPageSet in configdialog was replaced by ttk.Notebook.

• bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests. Patch mostly by Cheryl Sabella.

• bpo-31858: IDLE – Restrict shell prompt manipulation to the shell. Editor and output windows only see an empty last prompt line. This simplifies the code and fixes a minor bug when newline is inserted. Sys.ps1, if present, is read on Shell start-up, but is not set or changed.

• bpo-31860: The font sample in the IDLE configuration dialog is now editable. Changes persist while IDLE remains open

• bpo-31836: Test_code_module now passes if run after test_idle, which sets ps1.

  The code module uses sys.ps1 if present or sets it to ‘>>> ‘ if not. Test_code_module now properly tests both behaviors. Ditto for ps2.

• bpo-28603: Fix a TypeError that caused a shell restart when printing a traceback that includes an exception that is unhashable. Patch by Zane Bitter.

• bpo-13802: Use non-Latin characters in the IDLE’s Font settings sample. Even if one selects a font that defines a limited subset of the unicode Basic Multilingual Plane, tcl/tk will use other fonts that define a character. The expanded example give users of non-Latin characters a better idea of what they might see in IDLE’s shell and editors. To make room for the expanded sample, frames on the Font tab are re-arranged. The Font/Tabs help explains a bit about the additions.

• bpo-31460: Simplify the API of IDLE’s Module Browser.

  Passing a widget instead of an flist with a root widget opens the option of creating a browser frame that is only part of a window. Passing a full file name instead of pieces assumed to come from a .py file opens the possibility of browsing python files that do not end in .py.

• bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

• bpo-31559: Remove test order dependence in idle_test.test_browser.

• bpo-31459: Rename IDLE’s module browser from Class Browser to Module Browser. The original module-level class and method browser became a module browser, with the addition of module-level functions, years ago. Nested classes and functions were added yesterday. For back-compatibility, the virtual event <<open-class-browser>>, which appears on the Keys tab of the Settings dialog, is not changed. Patch by Cheryl Sabella.

• bpo-31500: Default fonts now are scaled on HiDPI displays.

• bpo-1612262: IDLE module browser now shows nested classes and functions. Original patches for code and tests by Guilherme Polo and Cheryl Sabella, respectively.

Tools/Demos

• bpo-30722: Make redemo work with Python 3.6 and newer versions.

  Also, remove the LOCALE option since it doesn’t work with string patterns in Python 3.

  Patch by Christoph Sarnowski.

C API

• bpo-20891: Fix PyGILState_Ensure(). When PyGILState_Ensure() is called in a non-Python thread before PyEval_InitThreads(), only call PyEval_InitThreads() after calling PyThreadState_New() to fix a crash.

• bpo-31532: Fix memory corruption due to allocator mix in getpath.c between Py_GetPath() and Py_SetPath()

• bpo-30697: The PyExc_RecursionErrorInst singleton is removed and PyErr_NormalizeException() does not use it anymore. This singleton is persistent and its members being never cleared may cause a segfault during finalization of the interpreter. See also bpo-22898.

Python 3.6.3 final

Release date: 2017-10-03

Library

• bpo-31641: Re-allow arbitrary iterables in concurrent.futures.as_completed(). Fixes regression in 3.6.3rc1.

Build

• bpo-31662: Fix typos in Windows uploadrelease.bat script. Fix Windows Doc build issues in Doc/make.bat.

• bpo-31423: Fix building the PDF documentation with newer versions of Sphinx.

Python 3.6.3 release candidate 1

Release date: 2017-09-18

Security

• bpo-29781: SSLObject.version() now correctly returns None when handshake over BIO has not been performed yet.

• bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to 2.2.3 to get security fixes.

Core and Builtins

• bpo-31471: Fix an assertion failure in subprocess.Popen() on Windows, in case the env argument has a bad keys() method. Patch by Oren Milman.

• bpo-31418: Fix an assertion failure in PyErr_WriteUnraisable() in case of an exception with a bad __module__ attribute. Patch by Oren Milman.

• bpo-31416: Fix assertion failures in case of a bad warnings.filters or warnings.defaultaction. Patch by Oren Milman.

• bpo-31411: Raise a TypeError instead of SystemError in case warnings.onceregistry is not a dictionary. Patch by Oren Milman.

• bpo-31373: Fix several possible instances of undefined behavior due to floating-point demotions.

• bpo-30465: Location information (lineno and col_offset) in f-strings is now (mostly) correct. This fixes tools like flake8 from showing warnings on the wrong line (typically the first line of the file).

• bpo-31343: Include sys/sysmacros.h for major(), minor(), and makedev(). GNU C libray plans to remove the functions from sys/types.h.

• bpo-31291: Fix an assertion failure in zipimport.zipimporter.get_data on Windows, when the return value of pathname.replace('/','\\') isn’t a string. Patch by Oren Milman.

• bpo-31271: Fix an assertion failure in the write() method of io.TextIOWrapper, when the encoder doesn’t return a bytes object. Patch by Oren Milman.

• bpo-31243: Fix a crash in some methods of io.TextIOWrapper, when the decoder’s state is invalid. Patch by Oren Milman.

• bpo-30721: print now shows correct usage hint for using Python 2 redirection syntax. Patch by Sanyam Khurana.

• bpo-31070: Fix a race condition in importlib _get_module_lock().

• bpo-31095: Fix potential crash during GC caused by tp_dealloc which doesn’t call PyObject_GC_UnTrack().

• bpo-31071: Avoid masking original TypeError in call with * unpacking when other arguments are passed.

• bpo-30978: str.format_map() now passes key lookup exceptions through. Previously any exception was replaced with a KeyError exception.

• bpo-30808: Use _Py_atomic API for concurrency-sensitive signal state.

• bpo-30876: Relative import from unloaded package now reimports the package instead of failing with SystemError. Relative import from non-package now fails with ImportError rather than SystemError.

• bpo-30703: Improve signal delivery.

  Avoid using Py_AddPendingCall from signal handler, to avoid calling signal-unsafe functions. The tests I’m adding here fail without the rest of the patch, on Linux and OS X. This means our signal delivery logic had defects (some signals could be lost).

• bpo-30765: Avoid blocking in pthread_mutex_lock() when PyThread_acquire_lock() is asked not to block.

• bpo-31161: Make sure the ‘Missing parentheses’ syntax error message is only applied to SyntaxError, not to subclasses. Patch by Martijn Pieters.

• bpo-30814: Fixed a race condition when import a submodule from a package.

• bpo-30597: print now shows expected input in custom error message when used as a Python 2 statement. Patch by Sanyam Khurana.

Library

• bpo-31499: xml.etree: Fix a crash when a parser is part of a reference cycle.

• bpo-28556: typing.get_type_hints now finds the right globalns for classes and modules by default (when no globalns was specified by the caller).

• bpo-28556: Speed improvements to the typing module. Original PRs by Ivan Levkivskyi and Mitar.

• bpo-31544: The C accelerator module of ElementTree ignored exceptions raised when looking up TreeBuilder target methods in XMLParser().

• bpo-31234: socket.create_connection() now fixes manually a reference cycle: clear the variable storing the last exception on success.

• bpo-31457: LoggerAdapter objects can now be nested.

• bpo-31400: Improves SSL error handling to avoid losing error numbers.

• bpo-28958: ssl.SSLContext() now uses OpenSSL error information when a context cannot be instantiated.

• bpo-27340: SSLSocket.sendall() now uses memoryview to create slices of data. This fixes support for all bytes-like object. It is also more efficient and avoids costly copies.

• bpo-31178: Fix string concatenation bug in rare error path in the subprocess module

• bpo-31350: Micro-optimize asyncio._get_running_loop() to become up to 10% faster.

• bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying of partial characters for UTF-8 input (libexpat bug 115): https://github.com/libexpat/libexpat/issues/115

• bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

• bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads to have a non repr() based thread name by default when no thread_name_prefix is supplied. They will now identify themselves as “ThreadPoolExecutor-y_n”.

• bpo-9146: Fix a segmentation fault in _hashopenssl when standard hash functions such as md5 are not available in the linked OpenSSL library. As in some special FIPS-140 build environments.

• bpo-27144: The map() and as_completed() iterators in concurrent.futures now avoid keeping a reference to yielded objects.

• bpo-10746: Fix ctypes producing wrong PEP 3118 type codes for integer types.

• bpo-22536: The subprocess module now sets the filename when FileNotFoundError is raised on POSIX systems due to the executable or cwd not being found.

• bpo-31249: concurrent.futures: WorkItem.run() used by ThreadPoolExecutor now breaks a reference cycle between an exception object and the WorkItem object.

• bpo-31247: xmlrpc.server now explicitly breaks reference cycles when using sys.exc_info() in code handling exceptions.

• bpo-30102: The ssl and hashlib modules now call OPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The function detects CPU features and enables optimizations on some CPU architectures such as POWER8. Patch is based on research from Gustavo Serra Scalet.

• bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

• bpo-31135: ttk: fix the destroy() method of LabeledScale and OptionMenu classes. Call the parent destroy() method even if the used attribute doesn’t exist. The LabeledScale.destroy() method now also explicitly clears label and scale attributes to help the garbage collector to destroy all widgets.

• bpo-31107: Fix copyreg._slotnames() mangled attribute calculation for classes whose name begins with an underscore. Patch by Shane Harvey.

• bpo-31061: Fixed a crash when using asyncio and threads.

• bpo-30502: Fix handling of long oids in ssl. Based on patch by Christian Heimes.

• bpo-30119: ftplib.FTP.putline() now throws ValueError on commands that contains CR or LF. Patch by Dong-hee Na.

• bpo-30595: multiprocessing.Queue.get() with a timeout now polls its reader in non-blocking mode if it succeeded to acquire the lock but the acquire took longer than the timeout.

• bpo-29403: Fix unittest.mock’s autospec to not fail on method-bound builtin functions. Patch by Aaron Gallagher.

• bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

• bpo-25684: Change ttk.OptionMenu radiobuttons to be unique across instances of OptionMenu.

• bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits until the thread completes, even if the thread was started by the same process which created the queue.

• bpo-29854: Fix segfault in readline when using readline’s history-size option. Patch by Nir Soffer.

• bpo-30319: socket.close() now ignores ECONNRESET error.

• bpo-30828: Fix out of bounds write in asyncio.CFuture.remove_done_callback().

• bpo-30807: signal.setitimer() may disable the timer when passed a tiny value.

  Tiny values (such as 1e-6) are valid non-zero values for setitimer(), which is specified as taking microsecond-resolution intervals. However, on some platform, our conversion routine could convert 1e-6 into a zero interval, therefore disabling the timer instead of (re-)scheduling it.

• bpo-30441: Fix bug when modifying os.environ while iterating over it

• bpo-30532: Fix email header value parser dropping folding white space in certain cases.

• bpo-30879: os.listdir() and os.scandir() now emit bytes names when called with bytes-like argument.

• bpo-30746: Prohibited the ‘=’ character in environment variable names in os.putenv() and os.spawn*().

• bpo-29755: Fixed the lgettext() family of functions in the gettext module. They now always return bytes.

Documentation

• bpo-31294: Fix incomplete code snippet in the ZeroMQSocketListener and ZeroMQSocketHandler examples and adapt them to Python 3.

• bpo-21649: Add RFC 7525 and Mozilla server side TLS links to SSL documentation.

• bpo-30803: Clarify doc on truth value testing. Original patch by Peter Thomassen.

Tests

• bpo-31320: Silence traceback in test_ssl

• bpo-25674: Remove sha256.tbs-internet.com ssl test

• bpo-30715: Address ALPN callback changes for OpenSSL 1.1.0f. The latest version behaves like OpenSSL 1.0.2 and no longer aborts handshake.

• bpo-30822: regrtest: Exclude tzdata from regrtest –all. When running the test suite using –use=all / -u all, exclude tzdata since it makes test_datetime too slow (15-20 min on some buildbots) which then times out on some buildbots. Fix also regrtest command line parser to allow passing -u extralargefile to run test_zipfile64.

Build

• bpo-30854: Fix compile error when compiling –without-threads. Patch by Masayuki Yamamoto.

Windows

• bpo-30389: Adds detection of Visual Studio 2017 to distutils on Windows.

• bpo-31340: Change to building with MSVC v141 (included with Visual Studio 2017)

• bpo-30581: os.cpu_count() now returns the correct number of processors on Windows when the number of logical processors is greater than 64.

• bpo-30731: Add a missing xmlns to python.manifest so that it matches the schema.

IDLE

• bpo-31493: IDLE code context – fix code update and font update timers.

  Canceling timers prevents a warning message when test_idle completes.

• bpo-31488: IDLE - Update non-key options in former extension classes. When applying configdialog changes, call .reload for each feature class. Change ParenMatch so updated options affect existing instances attached to existing editor windows.

• bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing whitespace strips more than blank spaces. Multiline string literals are not skipped.

• bpo-31480: IDLE - make tests pass with zzdummy extension disabled by default.

• bpo-31421: Document how IDLE runs tkinter programs. IDLE calls tcl/tk update in the background in order to make live

  interaction and experimentation with tkinter applications much easier.

• bpo-31414: IDLE – fix tk entry box tests by deleting first. Adding to an int entry is not the same as deleting and inserting because int(‘’) will fail.

• bpo-31051: Rearrange IDLE configdialog GenPage into Window, Editor, and Help sections.

• bpo-30617: IDLE - Add docstrings and tests for outwin subclass of editor.

  Move some data and functions from the class to module level. Patch by Cheryl Sabella.

• bpo-31287: IDLE - Do not modify tkinter.message in test_configdialog.

• bpo-27099: Convert IDLE’s built-in ‘extensions’ to regular features.

  About 10 IDLE features were implemented as supposedly optional extensions. Their different behavior could be confusing or worse for users and not good for maintenance. Hence the conversion.

  The main difference for users is that user configurable key bindings for builtin features are now handled uniformly. Now, editing a binding in a keyset only affects its value in the keyset. All bindings are defined together in the system-specific default keysets in config-extensions.def. All custom keysets are saved as a whole in config-extension.cfg. All take effect as soon as one clicks Apply or Ok.

  The affected events are ‘<<force-open-completions>>’, ‘<<expand-word>>’, ‘<<force-open-calltip>>’, ‘<<flash-paren>>’, ‘<<format-paragraph>>’, ‘<<run-module>>’, ‘<<check-module>>’, and ‘<<zoom-height>>’. Any (global) customizations made before 3.6.3 will not affect their keyset-specific customization after 3.6.3. and vice versa. Initial patch by Charles Wohlganger.

• bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog. Patch by Cheryl Sabella.

• bpo-31001: Add tests for configdialog highlight tab. Patch by Cheryl Sabella.

• bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog. The slightly modified tests continue to pass. Patch by Cheryl Sabella.

• bpo-31130: IDLE – stop leaks in test_configdialog. Initial patch by Victor Stinner.

• bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl Sabella.

• bpo-19903: IDLE: Calltips use inspect.signature instead of inspect.getfullargspec. This improves calltips for builtins converted to use Argument Clinic. Patch by Louie Lu.

• bpo-31083: IDLE - Add an outline of a TabPage class in configdialog. Update existing classes to match outline. Initial patch by Cheryl Sabella.

• bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The slightly modified tests continue to pass. Patch by Cheryl Sabella.

• bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog.

  Slightly modified tests continue to pass. Fix General tests. Patch mostly by Cheryl Sabella.

• bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry Jan Reedy and Cheryl Sabella.

• bpo-31060: IDLE - Finish rearranging methods of ConfigDialog Grouping methods pertaining to each tab and the buttons will aid writing tests and improving the tabs and will enable splitting the groups into classes.

• bpo-30853: IDLE – Factor a VarTrace class out of ConfigDialog.

  Instance tracers manages pairs consisting of a tk variable and a callback function. When tracing is turned on, setting the variable calls the function. Test coverage for the new class is 100%.

• bpo-31003: IDLE: Add more tests for General tab.

• bpo-30993: IDLE - Improve configdialog font page and tests.

  In configdialog: Document causal pathways in create_font_tab docstring. Simplify some attribute names. Move set_samples calls to var_changed_font (idea from Cheryl Sabella). Move related functions to positions after the create widgets function.

  In test_configdialog: Fix test_font_set so not order dependent. Fix renamed test_indent_scale so it tests the widget. Adjust tests for movement of set_samples call. Add tests for load functions. Put all font tests in one class and tab indent tests in another. Except for two lines, these tests completely cover the related functions.

• bpo-30981: IDLE – Add more configdialog font page tests.

• bpo-28523: IDLE: replace ‘colour’ with ‘color’ in configdialog.

• bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage from 46% to 96%. Patch by Louie Lu.

• bpo-30934: Document coverage details for idlelib tests.

  • Add section to idlelib/idle-test/README.txt.

  • Include check that branches are taken both ways.

  • Exclude IDLE-specific code that does not run during unit tests.

• bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets in docstrings This will facilitate improving the dialog and splitting up the class. Original patch by Cheryl Sabella.

• bpo-30899: IDLE: Add tests for ConfigParser subclasses in config. Patch by Louie Lu.

• bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl Sabella.

• bpo-30851: IDLE: Remove unused variables in configdialog. One is a duplicate, one is set but cannot be altered by users. Patch by Cheryl Sabella.

• bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys as well as mouse. Initial patch by Louie Lu.

• bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

• bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put in config; test. * In config, put dump test code in a function; run it and unittest in ‘if __name__ == ‘__main__’. * Add class config.ConfigChanges based on changes_class_v4.py on bpo issue. * Add class test_config.ChangesTest, partly using configdialog_tests_v1.py. * Revise configdialog to use ConfigChanges; see tracker msg297804. * Revise test_configdialog to match configdialog changes. * Remove configdialog functions unused or moved to ConfigChanges. Cheryl Sabella contributed parts of the patch.

• bpo-30777: IDLE: configdialog - Add docstrings and fix comments. Patch by Cheryl Sabella.

• bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and more tests. Patch by Cheryl Sabella.

• bpo-30723: IDLE: Make several improvements to parenmatch. Add ‘parens’ style to highlight both opener and closer. Make ‘default’ style, which is not default, a synonym for ‘opener’. Make time-delay work the same with all styles. Add help for config dialog extensions tab, including help for parenmatch. Add new tests. Original patch by Charles Wohlganger.

• bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl Sabella

• bpo-21519: IDLE’s basic custom key entry dialog now detects duplicates properly. Original patch by Saimadhav Heblikar.

• bpo-29910: IDLE no longer deletes a character after commenting out a region by a key shortcut. Add return 'break' for this and other potential conflicts between IDLE and default key bindings.

• bpo-30728: Review and change idlelib.configdialog names. Lowercase method and attribute names. Replace ‘colour’ with ‘color’, expand overly cryptic names, delete unneeded underscores. Replace import * with specific imports. Patches by Cheryl Sabella.

• bpo-6739: IDLE: Verify user-entered key sequences by trying to bind them with tk. Add tests for all 3 validation functions. Original patch by G Polo. Tests added by Cheryl Sabella.

Tools/Demos

• bpo-30983: gdb integration commands (py-bt, etc.) work on optimized shared builds now, too. PEP 523 introduced _PyEval_EvalFrameDefault which inlines PyEval_EvalFrameEx on non-debug shared builds. This broke the ability to use py-bt, py-up, and a few other Python-specific gdb integrations. The problem is fixed by only looking for _PyEval_EvalFrameDefault frames in python-gdb.py. Original patch by Bruno “Polaco” Penteado.

Python 3.6.2 final

Release date: 2017-07-17

No changes since release candidate 2

Python 3.6.2 release candidate 2

Release date: 2017-07-07

Security

• bpo-30730: Prevent environment variables injection in subprocess on Windows. Prevent passing other environment variables and command arguments.

• bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of multiple security vulnerabilities including: CVE-2017-9233 (External entity infinite loop DoS), CVE-2016-9063 (Integer overflow, re-fix), CVE-2016-0718 (Fix regression bugs from 2.2.0’s fix to CVE-2016-0718) and CVE-2012-0876 (Counter hash flooding with SipHash). Note: the CVE-2016-5300 (Use os-specific entropy sources like getrandom) doesn’t impact Python, since Python already gets entropy from the OS to set the expat secret using XML_SetHashSalt().

• bpo-30500: Fix urllib.parse.splithost() to correctly parse fragments. For example, splithost('//127.0.0.1#@evil.com/') now correctly returns the 127.0.0.1 host, instead of treating @evil.com as the host in an authentication (login@host).

Python 3.6.2 release candidate 1

Release date: 2017-06-17

Core and Builtins

• bpo-30682: Removed a too-strict assertion that failed for certain f-strings, such as eval(“f’\n’”) and eval(“f’\r’”).

• bpo-30604: Move co_extra_freefuncs to not be per-thread to avoid crashes

• bpo-29104: Fixed parsing backslashes in f-strings.

• bpo-27945: Fixed various segfaults with dict when input collections are mutated during searching, inserting or comparing. Based on patches by Duane Griffin and Tim Mitchell.

• bpo-25794: Fixed type.__setattr__() and type.__delattr__() for non-interned attribute names. Based on patch by Eryk Sun.

• bpo-30039: If a KeyboardInterrupt happens when the interpreter is in the middle of resuming a chain of nested ‘yield from’ or ‘await’ calls, it’s now correctly delivered to the innermost frame.

• bpo-12414: sys.getsizeof() on a code object now returns the sizes which includes the code struct and sizes of objects which it references. Patch by Dong-hee Na.

• bpo-29949: Fix memory usage regression of set and frozenset object.

• bpo-29935: Fixed error messages in the index() method of tuple, list and deque when pass indices of wrong type.

• bpo-29859: Show correct error messages when any of the pthread_* calls in thread_pthread.h fails.

• bpo-28876: bool(range) works even if len(range) raises OverflowError.

• bpo-29600: Fix wrapping coroutine return values in StopIteration.

• bpo-28856: Fix an oversight that %b format for bytes should support objects follow the buffer protocol.

• bpo-29714: Fix a regression that bytes format may fail when containing zero bytes inside.

• bpo-29478: If max_line_length=None is specified while using the Compat32 policy, it is no longer ignored. Patch by Mircea Cosbuc.

Library

• bpo-30616: Functional API of enum allows to create empty enums. Patched by Dong-hee Na

• bpo-30038: Fix race condition between signal delivery and wakeup file descriptor. Patch by Nathaniel Smith.

• bpo-23894: lib2to3 now recognizes rb'...' and f'...' strings.

• bpo-23890: unittest.TestCase.assertRaises() now manually breaks a reference cycle to not keep objects alive longer than expected.

• bpo-30149: inspect.signature() now supports callables with variable-argument parameters wrapped with partialmethod. Patch by Dong-hee Na.

• bpo-30645: Fix path calculation in imp.load_package(), fixing it for cases when a package is only shipped with bytecodes. Patch by Alexandru Ardelean.

• bpo-29931: Fixed comparison check for ipaddress.ip_interface objects. Patch by Sanjay Sundaresan.

• bpo-30605: re.compile() no longer raises a BytesWarning when compiling a bytes instance with misplaced inline modifier. Patch by Roy Williams.

Security

• bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes of CVE-2016-0718 and CVE-2016-4472. See https://sourceforge.net/p/expat/bugs/537/ for more information.

Library

• bpo-24484: Avoid race condition in multiprocessing cleanup (#2159)

• bpo-28994: The traceback no longer displayed for SystemExit raised in a callback registered by atexit.

• bpo-30508: Don’t log exceptions if Task/Future “cancel()” method was called.

• bpo-28556: Updates to typing module: Add generic AsyncContextManager, add support for ContextManager on all versions. Original PRs by Jelle Zijlstra and Ivan Levkivskyi

• bpo-29870: Fix ssl sockets leaks when connection is aborted in asyncio/ssl implementation. Patch by Michaël Sghaïer.

• bpo-29743: Closing transport during handshake process leaks open socket. Patch by Nikolay Kim

• bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by Mathieu Sornay.

• bpo-30418: On Windows, subprocess.Popen.communicate() now also ignore EINVAL on stdin.write() if the child process is still running but closed the pipe.

• bpo-29822: inspect.isabstract() now works during __init_subclass__. Patch by Nate Soares.

• bpo-29581: ABCMeta.__new__ now accepts **kwargs, allowing abstract base classes to use keyword parameters in __init_subclass__. Patch by Nate Soares.

• bpo-30557: faulthandler now correctly filters and displays exception codes on Windows

• bpo-30378: Fix the problem that logging.handlers.SysLogHandler cannot handle IPv6 addresses.

• bpo-29960: Preserve generator state when _random.Random.setstate() raises an exception. Patch by Bryan Olson.

• bpo-30414: multiprocessing.Queue._feed background running thread do not break from main loop on exception.

• bpo-30003: Fix handling escape characters in HZ codec. Based on patch by Ma Lin.

• bpo-30301: Fix AttributeError when using SimpleQueue.empty() under spawn and forkserver start methods.

• bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was attempted. This error occurs sometimes on SSL connections.

• bpo-30375: Warnings emitted when compile a regular expression now always point to the line in the user code. Previously they could point into inners of the re module if emitted from inside of groups or conditionals.

• bpo-30048: Fixed Task.cancel() can be ignored when the task is running coroutine and the coroutine returned without any more await.

• bpo-30266: contextlib.AbstractContextManager now supports anti-registration by setting __enter__ = None or __exit__ = None, following the pattern introduced in bpo-25958. Patch by Jelle Zijlstra.

• bpo-30298: Weaken the condition of deprecation warnings for inline modifiers. Now allowed several subsequential inline modifiers at the start of the pattern (e.g. '(?i)(?s)...'). In verbose mode whitespaces and comments now are allowed before and between inline modifiers (e.g. '(?x) (?i) (?s)...').

• bpo-29990: Fix range checking in GB18030 decoder. Original patch by Ma Lin.

• bpo-26293: Change resulted because of zipfile breakage. (See also: bpo-29094)

• bpo-30243: Removed the __init__ methods of _json’s scanner and encoder. Misusing them could cause memory leaks or crashes. Now scanner and encoder objects are completely initialized in the __new__ methods.

• bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper process when Ctrl-C is received.

• bpo-28556: Various updates to typing module: add typing.NoReturn type, use WrapperDescriptorType, minor bug-fixes. Original PRs by Jim Fasarakis-Hilliard and Ivan Levkivskyi.

• bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

• bpo-30070: Fixed leaks and crashes in errors handling in the parser module.

• bpo-30061: Fixed crashes in IOBase methods __next__() and readlines() when readline() or __next__() respectively return non-sizeable object. Fixed possible other errors caused by not checking results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

• bpo-30017: Allowed calling the close() method of the zip entry writer object multiple times. Writing to a closed writer now always produces a ValueError.

• bpo-30068: _io._IOBase.readlines will check if it’s closed first when hint is present.

• bpo-29694: Fixed race condition in pathlib mkdir with flags parents=True. Patch by Armin Rigo.

• bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions in contextlib.contextmanager. Patch by Siddharth Velankar.

• bpo-29998: Pickling and copying ImportError now preserves name and path attributes.

• bpo-29953: Fixed memory leaks in the replace() method of datetime and time objects when pass out of bound fold argument.

• bpo-29942: Fix a crash in itertools.chain.from_iterable when encountering long runs of empty iterables.

• bpo-27863: Fixed multiple crashes in ElementTree caused by race conditions and wrong types.

• bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising an exception at the very first of an iterable may swallow the exception or make the program hang. Patch by Davin Potts and Xiang Zhang.

• bpo-25803: Avoid incorrect errors raised by Path.mkdir(exist_ok=True) when the OS gives priority to errors such as EACCES over EEXIST.

• bpo-29861: Release references to tasks, their arguments and their results as soon as they are finished in multiprocessing.Pool.

• bpo-29884: faulthandler: Restore the old sigaltstack during teardown. Patch by Christophe Zeitouny.

• bpo-25455: Fixed crashes in repr of recursive buffered file-like objects.

• bpo-29800: Fix crashes in partial.__repr__ if the keys of partial.keywords are not strings. Patch by Michael Seifert.

• bpo-29742: get_extra_info() raises exception if get called on closed ssl transport. Patch by Nikolay Kim.

• bpo-8256: Fixed possible failing or crashing input() if attributes “encoding” or “errors” of sys.stdin or sys.stdout are not set or are not strings.

• bpo-28298: Fix a bug that prevented array ‘Q’, ‘L’ and ‘I’ from accepting big intables (objects that have __int__) as elements. Patch by Oren Milman.

• bpo-28231: The zipfile module now accepts path-like objects for external paths.

• bpo-26915: index() and count() methods of collections.abc.Sequence now check identity before checking equality when do comparisons.

• bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any other exception) to exception(s) raised in the dispatched methods. Patch by Petr Motejlek.

• bpo-30177: path.resolve(strict=False) no longer cuts the path after the first element not present in the filesystem. Patch by Antoine Pietri.

IDLE

• bpo-15786: Fix several problems with IDLE’s autocompletion box. The following should now work: clicking on selection box items; using the scrollbar; selecting an item by hitting Return. Hangs on MacOSX should no longer happen. Patch by Louie Lu.

• bpo-25514: Add doc subsubsection about IDLE failure to start. Popup no-connection message directs users to this section.

• bpo-30642: Fix reference leaks in IDLE tests. Patches by Louie Lu and Terry Jan Reedy.

• bpo-30495: Add docstrings for textview.py and use PEP8 names. Patches by Cheryl Sabella and Terry Jan Reedy.

• bpo-30290: Help-about: use pep8 names and add tests. Increase coverage to 100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan Reedy.

• bpo-30303: Add _utest option to textview; add new tests. Increase coverage to 100%. Patches by Louie Lu and Terry Jan Reedy.

C API

• bpo-27867: Function PySlice_GetIndicesEx() no longer replaced with a macro if Py_LIMITED_API is not set.

Build

• bpo-29941: Add --with-assertions configure flag to explicitly enable C assert() checks. Defaults to off. --with-pydebug implies --with-assertions.

• bpo-28787: Fix out-of-tree builds of Python when configured with --with--dtrace.

• bpo-29243: Prevent unnecessary rebuilding of Python during make test, make install and some other make targets when configured with --enable-optimizations.

• bpo-23404: Don’t regenerate generated files based on file modification time anymore: the action is now explicit. Replace make touch with make regen-all.

• bpo-29643: Fix --enable-optimization didn’t work.

Documentation

• bpo-30176: Add missing attribute related constants in curses documentation.

• bpo-30052: the link targets for bytes() and bytearray() are now their respective type definitions, rather than the corresponding builtin function entries. Use bytes and bytearray to reference the latter.

  In order to ensure this and future cross-reference updates are applied automatically, the daily documentation builds now disable the default output caching features in Sphinx.

• bpo-26985: Add missing info of code object in inspect documentation.

Tools/Demos

• bpo-29367: python-gdb.py now supports also method-wrapper (wrapperobject) objects.

Tests

• bpo-30357: test_thread: setUp() now uses support.threading_setup() and support.threading_cleanup() to wait until threads complete to avoid random side effects on following tests. Initial patch written by Grzegorz Grzywacz.

• bpo-30197: Enhanced functions swap_attr() and swap_item() in the test.support module. They now work when delete replaced attribute or item inside the with statement. The old value of the attribute or item (or None if it doesn’t exist) now will be assigned to the target of the “as” clause, if there is one.

Windows

• bpo-30687: Locate msbuild.exe on Windows when building rather than vcvarsall.bat

• bpo-30450: The build process on Windows no longer depends on Subversion, instead pulling external code from GitHub via a Python script. If Python 3.6 is not found on the system (via py -3.6), NuGet is used to download a copy of 32-bit Python.

Python 3.6.1 final

Release date: 2017-03-21

Core and Builtins

• bpo-29723: The sys.path[0] initialization change for bpo-29139 caused a regression by revealing an inconsistency in how sys.path is initialized when executing __main__ from a zipfile, directory, or other import location. The interpreter now consistently avoids ever adding the import location’s parent directory to sys.path, and ensures no other sys.path entries are inadvertently modified when inserting the import location named on the command line.

Build

• bpo-27593: fix format of git information used in sys.version

• Fix incompatible comment in python.h

Python 3.6.1 release candidate 1

Release date: 2017-03-04

Core and Builtins

• bpo-28893: Set correct __cause__ for errors about invalid awaitables returned from __aiter__ and __anext__.

• bpo-29683: Fixes to memory allocation in _PyCode_SetExtra. Patch by Brian Coleman.

• bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords. It should raise TypeError when kwargs is not a dict. But it might cause segv when args=NULL and kwargs is not a dict.

• bpo-28598: Support __rmod__ for subclasses of str being called before str.__mod__. Patch by Martijn Pieters.

• bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX. Patch by Matthieu Dartiailh.

• bpo-29602: Fix incorrect handling of signed zeros in complex constructor for complex subclasses and for inputs having a __complex__ method. Patch by Serhiy Storchaka.

• bpo-29347: Fixed possibly dereferencing undefined pointers when creating weakref objects.

• bpo-29438: Fixed use-after-free problem in key sharing dict.

• bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

• bpo-29337: Fixed possible BytesWarning when compare the code objects. Warnings could be emitted at compile time.

• bpo-29327: Fixed a crash when pass the iterable keyword argument to sorted().

• bpo-29034: Fix memory leak and use-after-free in os module (path_converter).

• bpo-29159: Fix regression in bytes(x) when x.__index__() raises Exception.

• bpo-28932: Do not include <sys/random.h> if it does not exist.

• bpo-25677: Correct the positioning of the syntax error caret for indented blocks. Based on patch by Michael Layzell.

• bpo-29000: Fixed bytes formatting of octals with zero padding in alternate form.

• bpo-26919: On Android, operating system data is now always encoded/decoded to/from UTF-8, instead of the locale encoding to avoid inconsistencies with os.fsencode() and os.fsdecode() which are already using UTF-8.

• bpo-28991: functools.lru_cache() was susceptible to an obscure reentrancy bug triggerable by a monkey-patched len() function.

• bpo-28739: f-string expressions are no longer accepted as docstrings and by ast.literal_eval() even if they do not include expressions.

• bpo-28512: Fixed setting the offset attribute of SyntaxError by PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

• bpo-28918: Fix the cross compilation of xxlimited when Python has been built with Py_DEBUG defined.

• bpo-28731: Optimize _PyDict_NewPresized() to create correct size dict. Improve speed of dict literal with constant keys up to 30%.

Library

• bpo-29169: Update zlib to 1.2.11.

• bpo-29623: Allow use of path-like object as a single argument in ConfigParser.read(). Patch by David Ellis.

• bpo-28963: Fix out of bound iteration in asyncio.Future.remove_done_callback implemented in C.

• bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer closes before all pipes are closed.

• bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C to accept None argument as their pure Python implementation.

• bpo-29703: Fix asyncio to support instantiation of new event loops in child processes.

• bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

• bpo-28624: Add a test that checks that cwd parameter of Popen() accepts PathLike objects. Patch by Sayan Chowdhury.

• bpo-28518: Start a transaction implicitly before a DML statement. Patch by Aviv Palivoda.

• bpo-29532: Altering a kwarg dictionary passed to functools.partial() no longer affects a partial object after creation.

• bpo-29110: Fix file object leak in aifc.open() when file is given as a filesystem path and is not in valid AIFF format. Patch by Anthony Zhang.

• bpo-28556: Various updates to typing module: typing.Counter, typing.ChainMap, improved ABC caching, etc. Original PRs by Jelle Zijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

• bpo-29100: Fix datetime.fromtimestamp() regression introduced in Python 3.6.0: check minimum and maximum years.

• bpo-29519: Fix weakref spewing exceptions during interpreter shutdown when used with a rare combination of multiprocessing and custom codecs.

• bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

• bpo-29444: Fixed out-of-bounds buffer access in the group() method of the match object. Based on patch by WGH.

• bpo-29335: Fix subprocess.Popen.wait() when the child process has exited to a stopped instead of terminated state (ex: when under ptrace).

• bpo-29290: Fix a regression in argparse that help messages would wrap at non-breaking spaces.

• bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

• bpo-29316: Restore the provisional status of typing module, add corresponding note to documentation. Patch by Ivan L.

• bpo-29219: Fixed infinite recursion in the repr of uninitialized ctypes.CDLL instances.

• bpo-29011: Fix an important omission by adding Deque to the typing module.

• bpo-28969: Fixed race condition in C implementation of functools.lru_cache. KeyError could be raised when cached function with full cache was simultaneously called from differen threads with the same uncached arguments.

• bpo-29142: In urllib.request, suffixes in no_proxy environment variable with leading dots could match related hostnames again (e.g. .b.c matches a.b.c). Patch by Milan Oberkirch.

• bpo-28961: Fix unittest.mock._Call helper: don’t ignore the name parameter anymore. Patch written by Jiajun Huang.

• bpo-29203: functools.lru_cache() now respects PEP 468 and preserves the order of keyword arguments. f(a=1, b=2) is now cached separately from f(b=2, a=1) since both calls could potentially give different results.

• bpo-15812: inspect.getframeinfo() now correctly shows the first line of a context. Patch by Sam Breese.

• bpo-29094: Offsets in a ZIP file created with extern file object and modes “w” and “x” now are relative to the start of the file.

• bpo-29085: Allow random.Random.seed() to use high quality OS randomness rather than the pid and time.

• bpo-29061: Fixed bug in secrets.randbelow() which would hang when given a negative input. Patch by Brendan Donegan.

• bpo-29079: Prevent infinite loop in pathlib.resolve() on Windows

• bpo-13051: Fixed recursion errors in large or resized curses.textpad.Textbox. Based on patch by Tycho Andersen.

• bpo-29119: Fix weakrefs in the pure python version of collections.OrderedDict move_to_end() method. Contributed by Andra Bogildea.

• bpo-9770: curses.ascii predicates now work correctly with negative integers.

• bpo-28427: old keys should not remove new values from WeakValueDictionary when collecting from another thread.

• bpo-28923: Remove editor artifacts from Tix.py.

• bpo-29055: Neaten-up empty population error on random.choice() by suppressing the upstream exception.

• bpo-28871: Fixed a crash when deallocate deep ElementTree.

• bpo-19542: Fix bugs in WeakValueDictionary.setdefault() and WeakValueDictionary.pop() when a GC collection happens in another thread.

• bpo-20191: Fixed a crash in resource.prlimit() when passing a sequence that doesn’t own its elements as limits.

• bpo-28779: multiprocessing.set_forkserver_preload() would crash the forkserver process if a preloaded module instantiated some multiprocessing objects such as locks.

• bpo-28847: dbm.dumb now supports reading read-only files and no longer writes the index file when it is not changed.

• bpo-26937: The chown() method of the tarfile.TarFile class does not fail now when the grp module cannot be imported, as for example on Android platforms.

IDLE

• bpo-29071: IDLE colors f-string prefixes (but not invalid ur prefixes).

• bpo-28572: Add 10% to coverage of IDLE’s test_configdialog. Update and augment description of the configuration system.

Windows

• bpo-29579: Removes readme.txt from the installer

• bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)

• bpo-28164: Correctly handle special console filenames (patch by Eryk Sun)

• bpo-29409: Implement PEP 529 for io.FileIO (Patch by Eryk Sun)

• bpo-29392: Prevent crash when passing invalid arguments into msvcrt module.

• bpo-25778: winreg does not truncate string correctly (Patch by Eryk Sun)

• bpo-28896: Deprecate WindowsRegistryFinder and disable it by default.

C API

• bpo-27867: Function PySlice_GetIndicesEx() is replaced with a macro if Py_LIMITED_API is not set or set to the value between 0x03050400 and 0x03060000 (not including) or 0x03060100 or higher.

• bpo-29083: Fixed the declaration of some public API functions. PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not available in limited API. PyArg_ValidateKeywordArguments(), PyArg_UnpackTuple() and Py_BuildValue() were not available in limited API of version < 3.3 when PY_SSIZE_T_CLEAN is defined.

• bpo-29058: All stable API extensions added after Python 3.2 are now available only when Py_LIMITED_API is set to the PY_VERSION_HEX value of the minimum Python version supporting this API.

Documentation

• bpo-28929: Link the documentation to its source file on GitHub.

• bpo-25008: Document smtpd.py as effectively deprecated and add a pointer to aiosmtpd, a third-party asyncio-based replacement.

• bpo-26355: Add canonical header link on each page to corresponding major version of the documentation. Patch by Matthias Bussonnier.

• bpo-29349: Fix Python 2 syntax in code for building the documentation.

Tests

• bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS. Skip some tests of select.poll when running on macOS due to unresolved issues with the underlying system poll function on some macOS versions.

• bpo-29571: to match the behaviour of the re.LOCALE flag, test_re.test_locale_flag now uses locale.getpreferredencoding(False) to determine the candidate encoding for the test regex (allowing it to correctly skip the test when the default locale encoding is a multi-byte encoding)

• bpo-28950: Disallow -j0 to be combined with -T/-l in regrtest command line arguments.

• bpo-28683: Fix the tests that bind() a unix socket and raise PermissionError on Android for a non-root user.

• bpo-26939: Add the support.setswitchinterval() function to fix test_functools hanging on the Android armv7 qemu emulator.

Build

• bpo-27593: sys.version and the platform module python_build(), python_branch(), and python_revision() functions now use git information rather than hg when building from a repo.

• bpo-29572: Update Windows build and OS X installers to use OpenSSL 1.0.2k.

• bpo-26851: Set Android compilation and link flags.

• bpo-28768: Fix implicit declaration of function _setmode. Patch by Masayuki Yamamoto

• bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

• bpo-23903: Added missed names to PC/python3.def.

• bpo-28762: lockf() is available on Android API level 24, but the F_LOCK macro is not defined in android-ndk-r13.

• bpo-28538: Fix the compilation error that occurs because if_nameindex() is available on Android API level 24, but the if_nameindex structure is not defined.

• bpo-20211: Do not add the directory for installing C header files and the directory for installing object code libraries to the cross compilation search paths. Original patch by Thomas Petazzoni.

• bpo-28849: Do not define sys.implementation._multiarch on Android.

Python 3.6.0 final

Release date: 2016-12-23

No changes since release candidate 2

Python 3.6.0 release candidate 2

Release date: 2016-12-16

Core and Builtins

• bpo-28147: Fix a memory leak in split-table dictionaries: setattr() must not convert combined table into split table. Patch written by INADA Naoki.

• bpo-28990: Fix asyncio SSL hanging if connection is closed before handshake is completed. (Patch by HoHo-Ho)

Tools/Demos

• bpo-28770: Fix python-gdb.py for fastcalls.

Windows

• bpo-28896: Deprecate WindowsRegistryFinder.

Build

• bpo-28898: Prevent gdb build errors due to HAVE_LONG_LONG redefinition.

Python 3.6.0 release candidate 1

Release date: 2016-12-06

Core and Builtins

• bpo-23722: Rather than silently producing a class that doesn’t support zero-argument super() in methods, failing to pass the new __classcell__ namespace entry up to type.__new__ now results in a DeprecationWarning and a class that supports zero-argument super().

• bpo-28797: Modifying the class __dict__ inside the __set_name__ method of a descriptor that is used inside that class no longer prevents calling the __set_name__ method of other descriptors.

• bpo-28782: Fix a bug in the implementation yield from when checking if the next instruction is YIELD_FROM. Regression introduced by WORDCODE (bpo-26647).

Library

• bpo-27030: Unknown escapes in re.sub() replacement template are allowed again. But they still are deprecated and will be disabled in 3.7.

• bpo-28835: Fix a regression introduced in warnings.catch_warnings(): call warnings.showwarning() if it was overriden inside the context manager.

• bpo-27172: To assist with upgrades from 2.7, the previously documented deprecation of inspect.getfullargspec() has been reversed. This decision may be revisited again after the Python 2.7 branch is no longer officially supported.

• bpo-26273: Add new socket.TCP_CONGESTION (Linux 2.6.13) and socket.TCP_USER_TIMEOUT (Linux 2.6.37) constants. Patch written by Omar Sandoval.

• bpo-24142: Reading a corrupt config file left configparser in an invalid state. Original patch by Florian Höch.

• bpo-28843: Fix asyncio C Task to handle exceptions __traceback__.

C API

• bpo-28808: PyUnicode_CompareWithASCIIString() now never raises exceptions.

Documentation

• bpo-23722: The data model reference and the porting section in the What’s New guide now cover the additional __classcell__ handling needed for custom metaclasses to fully support PEP 487 and zero-argument super().

Tools/Demos

• bpo-28023: Fix python-gdb.py didn’t support new dict implementation.

Python 3.6.0 beta 4

Release date: 2016-11-21

Core and Builtins

• bpo-28532: Show sys.version when -V option is supplied twice.

• bpo-27100: The with-statement now checks for __enter__ before it checks for __exit__. This gives less confusing error messages when both methods are missing. Patch by Jonathan Ellington.

• bpo-28746: Fix the set_inheritable() file descriptor method on platforms that do not have the ioctl FIOCLEX and FIONCLEX commands.

• bpo-26920: Fix not getting the locale’s charset upon initializing the interpreter, on platforms that do not have langinfo.

• bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS X when decode astral characters. Patch by Xiang Zhang.

• bpo-19398: Extra slash no longer added to sys.path components in case of empty compile-time PYTHONPATH components.

• bpo-28665: Improve speed of the STORE_DEREF opcode by 40%.

• bpo-28583: PyDict_SetDefault didn’t combine split table when needed. Patch by Xiang Zhang.

• bpo-27243: Change PendingDeprecationWarning -> DeprecationWarning. As it was agreed in the issue, __aiter__ returning an awaitable should result in PendingDeprecationWarning in 3.5 and in DeprecationWarning in 3.6.

• bpo-26182: Fix a refleak in code that raises DeprecationWarning.

• bpo-28721: Fix asynchronous generators aclose() and athrow() to handle StopAsyncIteration propagation properly.

Library

• bpo-28752: Restored the __reduce__() methods of datetime objects.

• bpo-28727: Regular expression patterns, _sre.SRE_Pattern objects created by re.compile(), become comparable (only x==y and x!=y operators). This change should fix the bpo-18383: don’t duplicate warning filters when the warnings module is reloaded (thing usually only done in unit tests).

• bpo-20572: The subprocess.Popen.wait method’s undocumented endtime parameter now raises a DeprecationWarning.

• bpo-25659: In ctypes, prevent a crash calling the from_buffer() and from_buffer_copy() methods on abstract classes like Array.

• bpo-19717: Makes Path.resolve() succeed on paths that do not exist. Patch by Vajrasky Kok

• bpo-28563: Fixed possible DoS and arbitrary code execution when handle plural form selections in the gettext module. The expression parser now supports exact syntax supported by GNU gettext.

• bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator when the garbage collector is invoked in other thread. Based on patch by Sebastian Cufre.

• bpo-28600: Optimize loop.call_soon.

• bpo-28613: Fix get_event_loop() return the current loop if called from coroutines/callbacks.

• bpo-28634: Fix asyncio.isfuture() to support unittest.Mock.

• bpo-26081: Fix refleak in _asyncio.Future.__iter__().throw.

• bpo-28639: Fix inspect.isawaitable to always return bool Patch by Justin Mayfield.

• bpo-28652: Make loop methods reject socket kinds they do not support.

• bpo-28653: Fix a refleak in functools.lru_cache.

• bpo-28703: Fix asyncio.iscoroutinefunction to handle Mock objects.

• bpo-28704: Fix create_unix_server to support Path-like objects (PEP 519).

• bpo-28720: Add collections.abc.AsyncGenerator.

Documentation

• bpo-28513: Documented command-line interface of zipfile.

Tests

• bpo-28666: Now test.support.rmtree is able to remove unwritable or unreadable directories.

• bpo-23839: Various caches now are cleared before running every test file.

Build

• bpo-10656: Fix out-of-tree building on AIX. Patch by Tristan Carel and Michael Haubenwallner.

• bpo-26359: Rename –with-optimiations to –enable-optimizations.

• bpo-28676: Prevent missing ‘getentropy’ declaration warning on macOS. Patch by Gareth Rees.

Python 3.6.0 beta 3

Release date: 2016-10-31

Core and Builtins

• bpo-28128: Deprecation warning for invalid str and byte escape sequences now prints better information about where the error occurs. Patch by Serhiy Storchaka and Eric Smith.

• bpo-28509: dict.update() no longer allocate unnecessary large memory.

• bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in debug build.

• bpo-28517: Fixed of-by-one error in the peephole optimizer that caused keeping unreachable code.

• bpo-28214: Improved exception reporting for problematic __set_name__ attributes.

• bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and exception loss in PyTraceBack_Here().

• bpo-28471: Fix “Python memory allocator called without holding the GIL” crash in socket.setblocking.

Library

• bpo-27517: LZMA compressor and decompressor no longer raise exceptions if given empty data twice. Patch by Benjamin Fogle.

• bpo-28549: Fixed segfault in curses’s addch() with ncurses6.

• bpo-28449: tarfile.open() with mode “r” or “r:” now tries to open a tar file with compression before trying to open it without compression. Otherwise it had 50% chance failed with ignore_zeros=True.

• bpo-23262: The webbrowser module now supports Firefox 36+ and derived browsers. Based on patch by Oleg Broytman.

• bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale caused by representing the scale as float value internally in Tk. tkinter.IntVar now works if float value is set to underlying Tk variable.

• bpo-18844: The various ways of specifying weights for random.choices() now produce the same result sequences.

• bpo-28255: calendar.TextCalendar().prmonth() no longer prints a space at the start of new line after printing a month’s calendar. Patch by Xiang Zhang.

• bpo-20491: The textwrap.TextWrapper class now honors non-breaking spaces. Based on patch by Kaarle Ritvanen.

• bpo-28353: os.fwalk() no longer fails on broken links.

• bpo-28430: Fix iterator of C implemented asyncio.Future doesn’t accept non-None value is passed to it.send(val).

• bpo-27025: Generated names for Tkinter widgets now start by the “!” prefix for readability.

• bpo-25464: Fixed HList.header_exists() in tkinter.tix module by addin a workaround to Tix library bug.

• bpo-28488: shutil.make_archive() no longer adds entry “./” to ZIP archive.

• bpo-25953: re.sub() now raises an error for invalid numerical group reference in replacement template even if the pattern is not found in the string. Error message for invalid group reference now includes the group index and the position of the reference. Based on patch by SilentGhost.

• bpo-18219: Optimize csv.DictWriter for large number of columns. Patch by Mariatta Wijaya.

• bpo-28448: Fix C implemented asyncio.Future didn’t work on Windows.

• bpo-28480: Fix error building socket module when multithreading is disabled.

• bpo-24452: Make webbrowser support Chrome on Mac OS X.

• bpo-20766: Fix references leaked by pdb in the handling of SIGINT handlers.

• bpo-28492: Fix how StopIteration exception is raised in _asyncio.Future.

• bpo-28500: Fix asyncio to handle async gens GC from another thread.

• bpo-26923: Fix asyncio.Gather to refuse being cancelled once all children are done. Patch by Johannes Ebke.

• bpo-26796: Don’t configure the number of workers for default threadpool executor. Initial patch by Hans Lawrenz.

• bpo-28544: Implement asyncio.Task in C.

Windows

• bpo-28522: Fixes mishandled buffer reallocation in getpathp.c

Build

• bpo-28444: Fix missing extensions modules when cross compiling.

• bpo-28208: Update Windows build and OS X installers to use SQLite 3.14.2.

• bpo-28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.

Tests

• bpo-26944: Fix test_posix for Android where ‘id -G’ is entirely wrong or missing the effective gid.

• bpo-28409: regrtest: fix the parser of command line arguments.

Python 3.6.0 beta 2

Release date: 2016-10-10

Core and Builtins

• bpo-28183: Optimize and cleanup dict iteration.

• bpo-26081: Added C implementation of asyncio.Future. Original patch by Yury Selivanov.

• bpo-28379: Added sanity checks and tests for PyUnicode_CopyCharacters(). Patch by Xiang Zhang.

• bpo-28376: The type of long range iterator is now registered as Iterator. Patch by Oren Milman.

• bpo-28376: Creating instances of range_iterator by calling range_iterator type now is deprecated. Patch by Oren Milman.

• bpo-28376: The constructor of range_iterator now checks that step is not 0. Patch by Oren Milman.

• bpo-26906: Resolving special methods of uninitialized type now causes implicit initialization of the type instead of a fail.

• bpo-18287: PyType_Ready() now checks that tp_name is not NULL. Original patch by Niklas Koep.

• bpo-24098: Fixed possible crash when AST is changed in process of compiling it.

• bpo-28201: Dict reduces possibility of 2nd conflict in hash table when hashes have same lower bits.

• bpo-28350: String constants with null character no longer interned.

• bpo-26617: Fix crash when GC runs during weakref callbacks.

• bpo-27942: String constants now interned recursively in tuples and frozensets.

• bpo-21578: Fixed misleading error message when ImportError called with invalid keyword args.

• bpo-28203: Fix incorrect type in complex(1.0, {2:3}) error message. Patch by Soumya Sharma.

• bpo-28086: Single var-positional argument of tuple subtype was passed unscathed to the C-defined function. Now it is converted to exact tuple.

• bpo-28214: Now __set_name__ is looked up on the class instead of the instance.

• bpo-27955: Fallback on reading /dev/urandom device when the getrandom() syscall fails with EPERM, for example when blocked by SECCOMP.

• bpo-28192: Don’t import readline in isolated mode.

• Upgrade internal unicode databases to Unicode version 9.0.0.

• bpo-28131: Fix a regression in zipimport’s compile_source(). zipimport should use the same optimization level as the interpreter.

• bpo-28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properly optimize memcpy().

• bpo-28120: Fix dict.pop() for splitted dictionary when trying to remove a “pending key” (Not yet inserted in split-table). Patch by Xiang Zhang.

• bpo-26182: Raise DeprecationWarning when async and await keywords are used as variable/attribute/class/function name.

Library

• bpo-27998: Fixed bytes path support in os.scandir() on Windows. Patch by Eryk Sun.

• bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

• bpo-26293: Fixed writing ZIP files that starts not from the start of the file. Offsets in ZIP file now are relative to the start of the archive in conforming to the specification.

• bpo-28380: unittest.mock Mock autospec functions now properly support assert_called, assert_not_called, and assert_called_once.

• bpo-27181: remove statistics.geometric_mean and defer until 3.7.

• bpo-28229: lzma module now supports pathlib.

• bpo-28321: Fixed writing non-BMP characters with binary format in plistlib.

• bpo-28225: bz2 module now supports pathlib. Initial patch by Ethan Furman.

• bpo-28227: gzip now supports pathlib. Patch by Ethan Furman.

• bpo-27358: Optimized merging var-keyword arguments and improved error message when passing a non-mapping as a var-keyword argument.

• bpo-28257: Improved error message when passing a non-iterable as a var-positional argument. Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

• bpo-28322: Fixed possible crashes when unpickle itertools objects from incorrect pickle data. Based on patch by John Leitch.

• bpo-28228: imghdr now supports pathlib.

• bpo-28226: compileall now supports pathlib.

• bpo-28314: Fix function declaration (C flags) for the getiterator() method of xml.etree.ElementTree.Element.

• bpo-28148: Stop using localtime() and gmtime() in the time module.

  Introduced platform independent _PyTime_localtime API that is similar to POSIX localtime_r, but available on all platforms. Patch by Ed Schouten.

• bpo-28253: Fixed calendar functions for extreme months: 0001-01 and 9999-12.

  Methods itermonthdays() and itermonthdays2() are reimplemented so that they don’t call itermonthdates() which can cause datetime.date under/overflow.

• bpo-28275: Fixed possible use after free in the decompress() methods of the LZMADecompressor and BZ2Decompressor classes. Original patch by John Leitch.

• bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation() if pass invalid string-like object as a name. Patch by Xiang Zhang.

• bpo-18844: random.choices() now has k as a keyword-only argument to improve the readability of common cases and come into line with the signature used in other languages.

• bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py. Patch by Madison May.

• bpo-27611: Fixed support of default root window in the tkinter.tix module. Added the master parameter in the DisplayStyle constructor.

• bpo-27348: In the traceback module, restore the formatting of exception messages like “Exception: None”. This fixes a regression introduced in 3.5a2.

• bpo-25651: Allow falsy values to be used for msg parameter of subTest().

• bpo-27778: Fix a memory leak in os.getrandom() when the getrandom() is interrupted by a signal and a signal handler raises a Python exception.

• bpo-28200: Fix memory leak on Windows in the os module (fix path_converter() function).

• bpo-25400: RobotFileParser now correctly returns default values for crawl_delay and request_rate. Initial patch by Peter Wirtz.

• bpo-27932: Prevent memory leak in win32_ver().

• Fix UnboundLocalError in socket._sendfile_use_sendfile.

• bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation of os.stat(). Patch by Eryk Sun.

• bpo-22493: Warning message emitted by using inline flags in the middle of regular expression now contains a (truncated) regex pattern. Patch by Tim Graham.

• bpo-25270: Prevent codecs.escape_encode() from raising SystemError when an empty bytestring is passed.

• bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

• bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch by Gergely Imreh and Markus Holtermann.

• bpo-28114: Fix a crash in parse_envlist() when env contains byte strings. Patch by Eryk Sun.

• bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and binascii.a2b_qp().

• bpo-27906: Fix socket accept exhaustion during high TCP traffic. Patch by Kevin Conway.

• bpo-28174: Handle when SO_REUSEPORT isn’t properly supported. Patch by Seth Michael Larson.

• bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__. Patch by iceboy.

• bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

• bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

• bpo-27759: Fix selectors incorrectly retain invalid file descriptors. Patch by Mark Williams.

• bpo-28368: Refuse monitoring processes if the child watcher has no loop attached. Patch by Vincent Michel.

• bpo-28369: Raise RuntimeError when transport’s FD is used with add_reader, add_writer, etc.

• bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by Коренберг Марк.

• bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

• bpo-28372: Fix asyncio to support formatting of non-python coroutines.

• bpo-28399: Remove UNIX socket from FS before binding. Patch by Коренберг Марк.

• bpo-27972: Prohibit Tasks to await on themselves.

Windows

• bpo-28402: Adds signed catalog files for stdlib on Windows.

• bpo-28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch by Eryk Sun)

• bpo-28251: Improvements to help manuals on Windows.

• bpo-28110: launcher.msi has different product codes between 32-bit and 64-bit

• bpo-28161: Opening CON for write access fails

• bpo-28162: WindowsConsoleIO readall() fails if first line starts with Ctrl+Z

• bpo-28163: WindowsConsoleIO fileno() passes wrong flags to _open_osfhandle

• bpo-28164: _PyIO_get_console_type fails for various paths

• bpo-28137: Renames Windows path file to ._pth

• bpo-28138: Windows ._pth file should allow import site

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