3.11.0a1 - Cpython — ContextQMD

.. bpo: 42278 .. date: 2021-08-29-12-39-44 .. nonce: jvmQz_ .. release date: 2021-10-05 .. section: Security

Replaced usage of :func:tempfile.mktemp with :class:~tempfile.TemporaryDirectory to avoid a potential race condition.

.. bpo: 44600 .. date: 2021-07-25-20-04-54 .. nonce: 0WMldg .. section: Security

Fix incorrect line numbers while tracing some failed patterns in :ref:match <match> statements. Patch by Charles Burkland.

.. bpo: 41180 .. date: 2021-06-29-23-40-22 .. nonce: uTWHv_ .. section: Security

Add auditing events to the :mod:marshal module, and stop raising code.__init__ events for every unmarshalled code object. Directly instantiated code objects will continue to raise an event, and audit event handlers should inspect or collect the raw marshal data. This reduces a significant performance overhead when loading from .pyc files.

.. bpo: 44394 .. date: 2021-06-29-02-45-53 .. nonce: A220N1 .. section: Security

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 .. date: 2021-05-08-11-50-46 .. nonce: 2CTM6M .. section: Security

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

.. bpo: 44022 .. date: 2021-05-05-17-37-04 .. nonce: bS3XJ9 .. section: Security

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

.. bpo: 43760 .. date: 2021-10-04-16-11-50 .. nonce: R9QoUv .. section: Core and Builtins

The number of hardware branches per instruction dispatch is reduced from two to one by adding a special instruction for tracing. Patch by Mark Shannon.

.. bpo: 45061 .. date: 2021-09-21-22-27-25 .. nonce: 5IOUf0 .. section: Core and Builtins

Add a deallocator to the bool type to detect refcount bugs in C extensions which call Py_DECREF(Py_True) or Py_DECREF(Py_False) by mistake. Detect also refcount bugs when the empty tuple singleton or the Unicode empty string singleton is destroyed by mistake. Patch by Victor Stinner.

.. bpo: 24076 .. date: 2021-09-20-10-02-12 .. nonce: ZFgFSj .. section: Core and Builtins

sum() was further optimised for summing up single digit integers.

.. bpo: 45190 .. date: 2021-09-14-10-02-12 .. nonce: ZFRgSj .. section: Core and Builtins

Update Unicode databases to Unicode 14.0.0.

.. bpo: 45167 .. date: 2021-09-14-09-23-59 .. nonce: CPSSoV .. section: Core and Builtins

Fix deepcopying of :class:types.GenericAlias objects.

.. bpo: 45155 .. date: 2021-09-09-15-05-17 .. nonce: JRw9TG .. section: Core and Builtins

:meth:int.to_bytes and :meth:int.from_bytes now take a default value of "big" for the byteorder argument. :meth:int.to_bytes also takes a default value of 1 for the length argument.

.. bpo: 44219 .. date: 2021-09-09-10-32-33 .. nonce: WiYyjz .. section: Library

Release the GIL while performing isatty system calls on arbitrary file descriptors. In particular, this affects :func:os.isatty, :func:os.device_encoding and :class:io.TextIOWrapper. By extension, :func:io.open in text mode is also affected. This change solves a deadlock in :func:os.isatty. Patch by Vincent Michel in :issue:44219.

.. bpo: 44959 .. date: 2021-09-08-08-29-41 .. nonce: OSwwPf .. section: Core and Builtins

Added fallback to extension modules with '.sl' suffix on HP-UX

.. bpo: 45121 .. date: 2021-09-07-17-10-16 .. nonce: iG-Hsf .. section: Library

Fix issue where Protocol.__init__ raises RecursionError when it's called directly or via super(). Patch provided by Yurii Karabas.

.. bpo: 44348 .. date: 2021-09-07-00-21-04 .. nonce: f8w_Td .. section: Core and Builtins

The deallocator function of the :exc:BaseException type now uses the trashcan mechanism to prevent stack overflow. For example, when a :exc:RecursionError instance is raised, it can be linked to another RecursionError through the __context__ attribute or the __traceback__ attribute, and then a chain of exceptions is created. When the chain is destroyed, nested deallocator function calls can crash with a stack overflow if the chain is too long compared to the available stack memory. Patch by Victor Stinner.

.. bpo: 45123 .. date: 2021-09-06-21-52-45 .. nonce: 8Eh9iI .. section: Core and Builtins

Fix PyAiter_Check to only check for the anext presence (not for aiter). Rename PyAiter_Check to PyAIter_Check, PyObject_GetAiter -> PyObject_GetAIter.

.. bpo: 1514420 .. date: 2021-09-03-16-18-10 .. nonce: 2Lumpj .. section: Core and Builtins

Interpreter no longer attempts to open files with names in angle brackets (like "<string>" or "<stdin>") when formatting an exception.

.. bpo: 41031 .. date: 2021-09-03-12-35-17 .. nonce: yPSJEs .. section: Core and Builtins

Match C and Python code formatting of unprintable exceptions and exceptions in the :mod:__main__ module.

.. bpo: 37330 .. date: 2021-09-02-01-28-01 .. nonce: QDjM_l .. section: Core and Builtins

:func:open, :func:io.open, :func:codecs.open and :class:fileinput.FileInput no longer accept 'U' ("universal newline") in the file mode. This flag was deprecated since Python 3.3. Patch by Victor Stinner.

.. bpo: 45083 .. date: 2021-09-01-23-55-49 .. nonce: cLi9G3 .. section: Core and Builtins

When the interpreter renders an exception, its name now has a complete qualname. Previously only the class name was concatenated to the module name, which sometimes resulted in an incorrect full name being displayed.

(This issue impacted only the C code exception rendering, the :mod:traceback module was using qualname already).

.. bpo: 34561 .. date: 2021-09-01-19-21-48 .. nonce: uMAVA- .. section: Core and Builtins

List sorting now uses the merge-ordering strategy from Munro and Wild's powersort(). Unlike the former strategy, this is provably near-optimal in the entropy of the distribution of run lengths. Most uses of list.sort() probably won't see a significant time difference, but may see significant improvements in cases where the former strategy was exceptionally poor. However, as these are all fast linear-time approximations to a problem that's inherently at best quadratic-time to solve truly optimally, it's also possible to contrive cases where the former strategy did better.

.. bpo: 45056 .. date: 2021-09-01-16-55-43 .. nonce: 7AK2d9 .. section: Core and Builtins

Compiler now removes trailing unused constants from co_consts.

.. bpo: 45020 .. date: 2021-08-31-17-44-51 .. nonce: ZPI_3L .. section: Core and Builtins

Add a new command line option, "-X frozen_modules=[on|off]" to opt out of (or into) using optional frozen modules. This defaults to "on" (or "off" if it's running out of the source tree).

.. bpo: 45012 .. date: 2021-08-31-11-09-52 .. nonce: ueeOcx .. section: Library

In :mod:posix, release GIL during stat(), lstat(), and fstatat() syscalls made by :func:os.DirEntry.stat. Patch by Stanisław Skonieczny.

.. bpo: 45018 .. date: 2021-08-26-18-44-03 .. nonce: pu8H9L .. section: Core and Builtins

Fixed pickling of range iterators that iterated for over 2**32 times.

.. bpo: 45000 .. date: 2021-08-25-23-17-32 .. nonce: XjmyLl .. section: Core and Builtins

A :exc:SyntaxError is now raised when trying to delete :const:__debug__. Patch by Donghee Na.

.. bpo: 44963 .. date: 2021-08-25-23-07-10 .. nonce: 5EET8y .. section: Core and Builtins

Implement send() and throw() methods for anext_awaitable objects. Patch by Pablo Galindo.

.. bpo: 44962 .. date: 2021-08-23-19-55-08 .. nonce: J00ftt .. section: Library

Fix a race in WeakKeyDictionary, WeakValueDictionary and WeakSet when two threads attempt to commit the last pending removal. This fixes asyncio.create_task and fixes a data loss in asyncio.run where shutdown_asyncgens is not run

.. bpo: 24234 .. date: 2021-08-23-10-36-55 .. nonce: MGVUQi .. section: Core and Builtins

Implement the :meth:__bytes__ special method on the :class:bytes type, so a bytes object b passes an isinstance(b, typing.SupportsBytes) check.

.. bpo: 24234 .. date: 2021-08-22-12-28-50 .. nonce: n3oTdx .. section: Core and Builtins

Implement the :meth:__complex__ special method on the :class:complex type, so a complex number z passes an isinstance(z, typing.SupportsComplex) check.

.. bpo: 44954 .. date: 2021-08-19-14-43-24 .. nonce: dLn3lg .. section: Core and Builtins

Fixed a corner case bug where the result of float.fromhex('0x.8p-1074') was rounded the wrong way.

.. bpo: 44947 .. date: 2021-08-18-19-09-28 .. nonce: mcvGdS .. section: Core and Builtins

Refine the syntax error for trailing commas in import statements. Patch by Pablo Galindo.

.. bpo: 44945 .. date: 2021-08-18-11-14-38 .. nonce: CO3s77 .. section: Core and Builtins

Specialize the BINARY_ADD instruction using the PEP 659 machinery. Adds five new instructions:

BINARY_ADD_ADAPTIVE
BINARY_ADD_FLOAT
BINARY_ADD_INT
BINARY_ADD_UNICODE
BINARY_ADD_UNICODE_INPLACE_FAST

.. bpo: 44929 .. date: 2021-08-16-23-16-17 .. nonce: qpMEky .. section: Library

Fix some edge cases of enum.Flag string representation in the REPL. Patch by Pablo Galindo.

.. bpo: 44914 .. date: 2021-08-16-11-36-02 .. nonce: 6Lgrx3 .. section: Core and Builtins

Class version tags are no longer recycled.

This means that a version tag serves as a unique identifier for the state of a class. We rely on this for effective specialization of the LOAD_ATTR and other instructions.

.. bpo: 44698 .. date: 2021-08-15-10-39-06 .. nonce: lITKNc .. section: Core and Builtins

Restore behaviour of complex exponentiation with integer-valued exponent of type :class:float or :class:complex.

.. bpo: 44895 .. date: 2021-08-14-20-13-21 .. nonce: Ic9m90 .. section: Core and Builtins

A debug variable :envvar:PYTHONDUMPREFSFILE is added for creating a dump file which is generated by :option:--with-trace-refs. Patch by Donghee Na.

.. bpo: 44900 .. date: 2021-08-12-14-00-57 .. nonce: w2gpwy .. section: Core and Builtins

Add five superinstructions for PEP 659 quickening:

LOAD_FAST LOAD_FAST
STORE_FAST LOAD_FAST
LOAD_FAST LOAD_CONST
LOAD_CONST LOAD_FAST
STORE_FAST STORE_FAST

.. bpo: 44889 .. date: 2021-08-11-20-45-02 .. nonce: 2T3nTn .. section: Core and Builtins

Initial implementation of adaptive specialization of LOAD_METHOD. The following specialized forms were added:

LOAD_METHOD_CACHED
LOAD_METHOD_MODULE
LOAD_METHOD_CLASS

.. bpo: 44890 .. date: 2021-08-11-16-46-27 .. nonce: PwNg8N .. section: Core and Builtins

Specialization stats are always collected in debug builds.

.. bpo: 44885 .. date: 2021-08-11-15-39-57 .. nonce: i4noUO .. section: Core and Builtins

Correct the ast locations of f-strings with format specs and repeated expressions. Patch by Pablo Galindo

.. bpo: 44878 .. date: 2021-08-11-14-12-41 .. nonce: pAbBfc .. section: Core and Builtins

Remove the loop from the bytecode interpreter. All instructions end with a DISPATCH macro, so the loop is now redundant.

.. bpo: 44878 .. date: 2021-08-11-12-03-52 .. nonce: nEhjLi .. section: Core and Builtins

Remove switch statement for interpreter loop when using computed gotos. This makes sure that we only have one dispatch table in the interpreter.

.. bpo: 44874 .. date: 2021-08-09-19-05-20 .. nonce: oOcfU4 .. section: Core and Builtins

Deprecate the old trashcan macros (Py_TRASHCAN_SAFE_BEGIN/Py_TRASHCAN_SAFE_END). They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

.. bpo: 44872 .. date: 2021-08-09-16-16-03 .. nonce: OKRlhK .. section: Core and Builtins

Use new trashcan macros (Py_TRASHCAN_BEGIN/END) in frameobject.c instead of the old ones (Py_TRASHCAN_SAFE_BEGIN/END).

.. bpo: 33930 .. date: 2021-08-09-14-29-52 .. nonce: --5LQ- .. section: Core and Builtins

Fix segmentation fault with deep recursion when cleaning method objects. Patch by Augusto Goulart and Pablo Galindo.

.. bpo: 25782 .. date: 2021-08-07-21-39-19 .. nonce: B22lMx .. section: Core and Builtins

Fix bug where PyErr_SetObject hangs when the current exception has a cycle in its context chain.

.. bpo: 44856 .. date: 2021-08-07-01-26-12 .. nonce: 9rk3li .. section: Core and Builtins

Fix reference leaks in the error paths of update_bases() and __build_class__. Patch by Pablo Galindo.

.. bpo: 44826 .. date: 2021-08-05-17-49-55 .. nonce: zQsyK5 .. section: Core and Builtins

Initial implementation of adaptive specialization of STORE_ATTR

Three specialized forms of STORE_ATTR are added:

STORE_ATTR_SLOT
STORE_ATTR_SPLIT_KEYS
STORE_ATTR_WITH_HINT

.. bpo: 44838 .. date: 2021-08-05-17-42-03 .. nonce: r_Lkj_ .. section: Core and Builtins

Fixed a bug that was causing the parser to raise an incorrect custom :exc:SyntaxError for invalid 'if' expressions. Patch by Pablo Galindo.

.. bpo: 44821 .. date: 2021-08-04-11-37-38 .. nonce: 67YHGI .. section: Core and Builtins

Create instance dictionaries (dict) eagerly, to improve regularity of object layout and assist specialization.

.. bpo: 44792 .. date: 2021-07-31-12-12-57 .. nonce: mOReTW .. section: Core and Builtins

Improve syntax errors for if expressions. Patch by Miguel Brito

.. bpo: 34013 .. date: 2021-07-27-11-14-22 .. nonce: SjLFe- .. section: Core and Builtins

Generalize the invalid legacy statement custom error message (like the one generated when "print" is called without parentheses) to include more generic expressions. Patch by Pablo Galindo

.. bpo: 44732 .. date: 2021-07-26-15-27-03 .. nonce: IxObt3 .. section: Core and Builtins

Rename types.Union to types.UnionType.

.. bpo: 44725 .. date: 2021-07-23-15-17-01 .. nonce: qcuKaa .. section: Core and Builtins

Expose specialization stats in python via :func:!_opcode.get_specialization_stats.

.. bpo: 44717 .. date: 2021-07-23-01-52-13 .. nonce: -vVmAh .. section: Core and Builtins

Improve AttributeError on circular imports of submodules.

.. bpo: 44698 .. date: 2021-07-21-15-26-56 .. nonce: DA4_0o .. section: Core and Builtins

Fix undefined behaviour in complex object exponentiation.

.. bpo: 44653 .. date: 2021-07-19-20-49-06 .. nonce: WcqGyI .. section: Core and Builtins

Support :mod:typing types in parameter substitution in the union type.

.. bpo: 44676 .. date: 2021-07-19-19-53-46 .. nonce: WgIMvh .. section: Core and Builtins

Add ability to serialise types.Union objects. Patch provided by Yurii Karabas.

.. bpo: 44633 .. date: 2021-07-17-21-04-04 .. nonce: 5-zKeI .. section: Core and Builtins

Parameter substitution of the union type with wrong types now raises TypeError instead of returning :data:NotImplemented.

.. bpo: 44661 .. date: 2021-07-17-14-20-59 .. nonce: BQbXiH .. section: Core and Builtins

Update property_descr_set to use vectorcall if possible. Patch by Donghee Na.

.. bpo: 44662 .. date: 2021-07-17-13-41-58 .. nonce: q22kWR .. section: Core and Builtins

Add __module__ to types.Union. This also fixes types.Union issues with typing.Annotated. Patch provided by Yurii Karabas.

.. bpo: 44655 .. date: 2021-07-16-21-35-14 .. nonce: 95I7M6 .. section: Core and Builtins

Include the name of the type in unset slots attribute errors. Patch by Pablo Galindo

.. bpo: 44655 .. date: 2021-07-16-20-25-37 .. nonce: I3wRjL .. section: Core and Builtins

Don't include a missing attribute with the same name as the failing one when offering suggestions for missing attributes. Patch by Pablo Galindo

.. bpo: 44646 .. date: 2021-07-16-09-59-13 .. nonce: Yb6s05 .. section: Core and Builtins

Fix the hash of the union type: it no longer depends on the order of arguments.

.. bpo: 44636 .. date: 2021-07-16-09-36-12 .. nonce: ZWebi8 .. section: Core and Builtins

Collapse union of equal types. E.g. the result of int | int is now int. Fix comparison of the union type with non-hashable objects. E.g. int | str == {} no longer raises a TypeError.

.. bpo: 44611 .. date: 2021-07-16-01-01-11 .. nonce: LcfHN- .. section: Library

On Windows, :func:os.urandom: uses BCryptGenRandom API instead of CryptGenRandom API which is deprecated from Microsoft Windows API. Patch by Donghee Na.

.. bpo: 44635 .. date: 2021-07-14-13-54-07 .. nonce: 7ZMAdB .. section: Core and Builtins

Convert None to type(None) in the union type constructor.

.. bpo: 26280 .. date: 2021-07-14-10-31-10 .. nonce: cgpM4B .. section: Core and Builtins

Implement adaptive specialization for BINARY_SUBSCR

Three specialized forms of BINARY_SUBSCR are added:

BINARY_SUBSCR_LIST_INT
BINARY_SUBSCR_TUPLE_INT
BINARY_SUBSCR_DICT

.. bpo: 44589 .. date: 2021-07-13-23-19-41 .. nonce: 59OH8T .. section: Core and Builtins

Mapping patterns in match statements with two or more equal literal keys will now raise a :exc:SyntaxError at compile-time.

.. bpo: 44606 .. date: 2021-07-13-20-22-12 .. nonce: S3Bv2w .. section: Core and Builtins

Fix __instancecheck__ and __subclasscheck__ for the union type.

.. bpo: 42073 .. date: 2021-07-13-17-47-32 .. nonce: 9wopiC .. section: Core and Builtins

The @classmethod decorator can now wrap other classmethod-like descriptors.

.. bpo: 41972 .. date: 2021-07-12-04-06-57 .. nonce: nDX5k_ .. section: Core and Builtins

Tuned the string-searching algorithm of fastsearch.h to have a shorter inner loop for most cases.

.. bpo: 44590 .. date: 2021-07-09-12-08-17 .. nonce: a2ntVX .. section: Core and Builtins

All necessary data for executing a Python function (local variables, stack, etc) is now kept in a per-thread stack. Frame objects are lazily allocated on demand. This increases performance by about 7% on the standard benchmark suite. Introspection and debugging are unaffected as frame objects are always available when needed. Patch by Mark Shannon.

.. bpo: 44584 .. date: 2021-07-08-12-18-56 .. nonce: qKnSqV .. section: Core and Builtins

The threading debug (:envvar:!PYTHONTHREADDEBUG environment variable) is deprecated in Python 3.10 and will be removed in Python 3.12. This feature requires a debug build of Python. Patch by Victor Stinner.

.. bpo: 43895 .. date: 2021-07-07-16-05-35 .. nonce: JFjR0- .. section: Core and Builtins

An obsolete internal cache of shared object file handles added in 1995 that attempted, but did not guarantee, that a .so would not be dlopen'ed twice to work around flaws in mid-1990s posix-ish operating systems has been removed from dynload_shlib.c.

.. bpo: 44490 .. date: 2021-07-06-22-22-15 .. nonce: BJxPbZ .. section: Library

:mod:typing now searches for type parameters in types.Union objects. get_type_hints will also properly resolve annotations with nested types.Union objects. Patch provided by Yurii Karabas.

.. bpo: 43950 .. date: 2021-07-06-15-27-11 .. nonce: LhL2-q .. section: Core and Builtins

Code objects can now provide the column information for instructions when available. This is levaraged during traceback printing to show the expressions responsible for errors.

Contributed by Pablo Galindo, Batuhan Taskaya and Ammar Askar as part of :pep:657.

.. bpo: 44562 .. date: 2021-07-04-23-38-51 .. nonce: QdeRQo .. section: Core and Builtins

Remove uses of :c:func:PyObject_GC_Del in error path when initializing :class:types.GenericAlias.

.. bpo: 41486 .. date: 2021-07-04-17-41-47 .. nonce: DiM24a .. section: Library

Fix a memory consumption and copying performance regression in earlier 3.10 beta releases if someone used an output buffer larger than 4GiB with zlib.decompress on input data that expands that large.

.. bpo: 43908 .. date: 2021-07-03-00-20-39 .. nonce: YHuV_s .. section: Core and Builtins

Heap types with the :c:macro:Py_TPFLAGS_IMMUTABLETYPE flag can now inherit the :pep:590 vectorcall protocol. Previously, this was only possible for :ref:static types <static-types>. Patch by Erlend E. Aasland.

.. bpo: 44553 .. date: 2021-07-02-22-54-41 .. nonce: l9YqGg .. section: Core and Builtins

Implement GC methods for types.Union to break reference cycles and prevent memory leaks.

.. bpo: 44490 .. date: 2021-07-01-11-59-34 .. nonce: xY80VR .. section: Core and Builtins

Add __parameters__ attribute and __getitem__ operator to types.Union. Patch provided by Yurii Karabas.

.. bpo: 44523 .. date: 2021-06-29-11-49-29 .. nonce: 67-ZIP .. section: Core and Builtins

Remove the pass-through for :func:hash of :class:weakref.proxy objects to prevent unintended consequences when the original referred object dies while the proxy is part of a hashable object. Patch by Pablo Galindo.

.. bpo: 44483 .. date: 2021-06-22-19-08-19 .. nonce: eq2f7T .. section: Core and Builtins

Fix a crash in types.Union objects when creating a union of an object with bad __module__ field.

.. bpo: 44486 .. date: 2021-06-22-10-55-23 .. nonce: wct-9X .. section: Core and Builtins

Modules will always have a dictionary, even when created by types.ModuleType.__new__()

.. bpo: 44472 .. date: 2021-06-21-11-19-54 .. nonce: Vvm1yn .. section: Core and Builtins

Fix ltrace functionality when exceptions are raised. Patch by Pablo Galindo

.. bpo: 12022 .. date: 2021-06-20-10-53-21 .. nonce: SW240M .. section: Core and Builtins

A :exc:TypeError is now raised instead of an :exc:AttributeError in :keyword:with and :keyword:async with statements for objects which do not support the :term:context manager or :term:asynchronous context manager protocols correspondingly.

.. bpo: 44297 .. date: 2021-06-19-12-41-13 .. nonce: F53vHj .. section: Core and Builtins

Make sure that the line number is set when entering a comprehension scope. This ensures that backtraces including generator expressions show the correct line number.

.. bpo: 44456 .. date: 2021-06-18-22-08-25 .. nonce: L0Rhko .. section: Core and Builtins

Improve the syntax error when mixing positional and keyword patterns. Patch by Pablo Galindo.

.. bpo: 44409 .. date: 2021-06-13-23-12-18 .. nonce: eW4LS- .. section: Core and Builtins

Fix error location information for tokenizer errors raised on initialization of the tokenizer. Patch by Pablo Galindo.

.. bpo: 44396 .. date: 2021-06-11-18-17-42 .. nonce: Z9EKim .. section: Core and Builtins

Fix a possible crash in the tokenizer when raising syntax errors for unclosed strings. Patch by Pablo Galindo.

.. bpo: 44376 .. date: 2021-06-11-17-37-15 .. nonce: zhM1UW .. section: Core and Builtins

Exact integer exponentiation (like i**2 or pow(i, 2)) with a small exponent is much faster, due to reducing overhead in such cases.

.. bpo: 44313 .. date: 2021-06-10-16-10-39 .. nonce: 34RjI8 .. section: Core and Builtins

Directly imported objects and modules (through import and from import statements) don't generate LOAD_METHOD/CALL_METHOD for directly accessed objects on their namespace. They now use the regular LOAD_ATTR/CALL_FUNCTION.

.. bpo: 44338 .. date: 2021-06-10-10-06-18 .. nonce: c4Myr4 .. section: Core and Builtins

Implement adaptive specialization for LOAD_GLOBAL

Two specialized forms of LOAD_GLOBAL are added:

LOAD_GLOBAL_MODULE
LOAD_GLOBAL_BUILTIN

.. bpo: 44368 .. date: 2021-06-09-22-56-59 .. nonce: vgT0Cx .. section: Core and Builtins

Improve syntax errors for invalid "as" targets. Patch by Pablo Galindo

.. bpo: 44349 .. date: 2021-06-08-22-49-06 .. nonce: xgEgeA .. section: Core and Builtins

Fix an edge case when displaying text from files with encoding in syntax errors. Patch by Pablo Galindo.

.. bpo: 44337 .. date: 2021-06-08-10-22-46 .. nonce: RTjmIt .. section: Core and Builtins

Initial implementation of adaptive specialization of LOAD_ATTR

Four specialized forms of LOAD_ATTR are added:

LOAD_ATTR_SLOT
LOAD_ATTR_SPLIT_KEYS
LOAD_ATTR_WITH_HINT
LOAD_ATTR_MODULE

.. bpo: 44335 .. date: 2021-06-08-01-13-47 .. nonce: GQTTkl .. section: Core and Builtins

Fix a regression when identifying incorrect characters in syntax errors. Patch by Pablo Galindo

.. bpo: 43693 .. date: 2021-06-07-15-13-44 .. nonce: c_zDeY .. section: Core and Builtins

Computation of the offsets of cell variables is done in the compiler instead of at runtime. This reduces the overhead of handling cell and free variables, especially in the case where a variable is both an argument and cell variable.

.. bpo: 44317 .. date: 2021-06-06-00-29-14 .. nonce: xPPhcZ .. section: Core and Builtins

Improve tokenizer error with improved locations. Patch by Pablo Galindo.

.. bpo: 44304 .. date: 2021-06-05-02-34-57 .. nonce: _MAoPc .. section: Library

Fix a crash in the :mod:sqlite3 module that happened when the garbage collector clears :class:sqlite.Statement objects. Patch by Pablo Galindo

.. bpo: 44305 .. date: 2021-06-03-22-51-50 .. nonce: 66dVDG .. section: Core and Builtins

Improve error message for try blocks without except or finally blocks. Patch by Pablo Galindo.

.. bpo: 43413 .. date: 2021-05-30-16-37-47 .. nonce: vYFPPC .. section: Core and Builtins

Constructors of subclasses of some builtin classes (e.g. :class:tuple, :class:list, :class:frozenset) no longer accept arbitrary keyword arguments. [reverted in 3.11a4] Subclass of :class:set can now define a __new__() method with additional keyword parameters without overriding also __init__().

.. bpo: 43667 .. date: 2021-05-27-17-34-29 .. nonce: ND9jP3 .. section: Core and Builtins

Improve Unicode support in non-UTF locales on Oracle Solaris. This issue does not affect other Solaris systems.

.. bpo: 43693 .. date: 2021-05-26-19-10-47 .. nonce: 1KSG9u .. section: Core and Builtins

A new opcode MAKE_CELL has been added that effectively moves some of the work done on function entry into the compiler and into the eval loop. In addition to creating the required cell objects, the new opcode converts relevant arguments (and other locals) to cell variables on function entry.

.. bpo: 44232 .. date: 2021-05-25-18-20-10 .. nonce: DMcCCf .. section: Core and Builtins

Fix a regression in :func:type when a metaclass raises an exception. The C function :c:func:type_new must properly report the exception when a metaclass constructor raises an exception and the winner class is not the metaclass. Patch by Victor Stinner.

.. bpo: 44201 .. date: 2021-05-21-21-16-03 .. nonce: bGaSjt .. section: Core and Builtins

Avoid side effects of checking for specialized syntax errors in the REPL that was causing it to ask for extra tokens after a syntax error had been detected. Patch by Pablo Galindo

.. bpo: 43693 .. date: 2021-05-21-20-53-49 .. nonce: -NN3J_ .. section: Core and Builtins

PyCodeObject gained co_fastlocalnames and co_fastlocalkinds as the authoritative source of fast locals info. Marshaled code objects have changed accordingly.

.. bpo: 44184 .. date: 2021-05-21-01-42-45 .. nonce: 9qOptC .. section: Core and Builtins

Fix a crash at Python exit when a deallocator function removes the last strong reference to a heap type. Patch by Victor Stinner.

.. bpo: 44187 .. date: 2021-05-20-12-43-04 .. nonce: 3lk0L1 .. section: Core and Builtins

Implement quickening in the interpreter. This offers no advantages as yet, but is an enabler of future optimizations. See PEP 659 for full explanation.

.. bpo: 44180 .. date: 2021-05-19-20-33-36 .. nonce: mQVaAs .. section: Core and Builtins

The parser doesn't report generic syntax errors that happen in a position further away that the one it reached in the first pass. Patch by Pablo Galindo

.. bpo: 44168 .. date: 2021-05-18-11-27-02 .. nonce: mgB-rt .. section: Core and Builtins

Fix error message in the parser involving keyword arguments with invalid expressions. Patch by Pablo Galindo

.. bpo: 44156 .. date: 2021-05-17-20-44-45 .. nonce: 8KSp9l .. section: Core and Builtins

String caches in compile.c are now subinterpreter compatible.

.. bpo: 44143 .. date: 2021-05-15-17-30-57 .. nonce: 7UTS6H .. section: Core and Builtins

Fixed a crash in the parser that manifest when raising tokenizer errors when an existing exception was present. Patch by Pablo Galindo.

.. bpo: 44032 .. date: 2021-05-14-20-03-32 .. nonce: OzT1ob .. section: Core and Builtins

Move 'fast' locals and other variables from the frame object to a per-thread datastack.

.. bpo: 44114 .. date: 2021-05-12-14-26-16 .. nonce: p-WfAE .. section: Core and Builtins

Fix incorrect dictkeys_reversed and dictitems_reversed function signatures in C code, which broke webassembly builds.

.. bpo: 44110 .. date: 2021-05-11-21-52-44 .. nonce: VqbAsB .. section: Core and Builtins

Improve :func:str.__getitem__ error message

.. bpo: 26110 .. date: 2021-05-10-18-49-13 .. nonce: EQzqqA .. section: Core and Builtins

Add CALL_METHOD_KW opcode to speed up method calls with keyword arguments. Idea originated from PyPy. A side effect is executing CALL_METHOD is now branchless in the evaluation loop.

.. bpo: 28307 .. date: 2021-05-08-19-54-57 .. nonce: 7ysaVW .. section: Core and Builtins

Compiler now optimizes simple C-style formatting with literal format containing only format codes %s, %r and %a by converting them to f-string expressions.

.. bpo: 43149 .. date: 2021-05-08-17-18-37 .. nonce: Kp5FxD .. section: Core and Builtins

Correct the syntax error message regarding multiple exception types to not refer to "exception groups". Patch by Pablo Galindo

.. bpo: 43822 .. date: 2021-05-04-01-01-04 .. nonce: 9VeCg0 .. section: Core and Builtins

The parser will prioritize tokenizer errors over custom syntax errors when raising exceptions. Patch by Pablo Galindo.

.. bpo: 40222 .. date: 2021-04-30-15-48-36 .. nonce: j3VxeX .. section: Core and Builtins

"Zero cost" exception handling.

Uses a lookup table to determine how to handle exceptions.
Removes SETUP_FINALLY and POP_TOP block instructions, eliminating the runtime overhead of try statements.
Reduces the size of the frame object by about 60%.

Patch by Mark Shannon

.. bpo: 43918 .. date: 2021-04-23-03-46-45 .. nonce: nNDY3S .. section: Core and Builtins

Document the signature and default argument in the docstring of the new anext builtin.

.. bpo: 43833 .. date: 2021-04-18-18-07-33 .. nonce: oChkCi .. section: Core and Builtins

Emit a deprecation warning if the numeric literal is immediately followed by one of keywords: and, else, for, if, in, is, or. Raise a syntax error with more informative message if it is immediately followed by other keyword or identifier.

.. bpo: 43879 .. date: 2021-04-17-16-08-00 .. nonce: zkyJgh .. section: Core and Builtins

Add native_thread_id to PyThreadState. Patch by Gabriele N. Tornetta.

.. bpo: 43693 .. date: 2021-04-02-15-02-16 .. nonce: l3Ureu .. section: Core and Builtins

Compute cell offsets relative to locals in compiler. Allows the interpreter to treats locals and cells a single array, which is slightly more efficient. Also make the LOAD_CLOSURE opcode an alias for LOAD_FAST. Preserving LOAD_CLOSURE helps keep bytecode a bit more readable.

.. bpo: 17792 .. date: 2021-03-22-17-50-30 .. nonce: _zssjS .. section: Core and Builtins

More accurate error messages for access of unbound locals or free vars.

.. bpo: 28146 .. date: 2021-01-13-19-34-41 .. nonce: AZBBkH .. section: Core and Builtins

Fix a confusing error message in :func:str.format.

.. bpo: 11105 .. date: 2020-06-02-13-21-14 .. nonce: wceryW .. section: Core and Builtins

When compiling :class:ast.AST objects with recursive references through :func:compile, the interpreter doesn't crash anymore instead it raises a :exc:RecursionError.

.. bpo: 39091 .. date: 2019-12-21-14-18-32 .. nonce: dOexgQ .. section: Core and Builtins

Fix crash when using passing a non-exception to a generator's throw() method. Patch by Noah Oxer

.. bpo: 33346 .. date: 2018-05-11-12-44-03 .. nonce: ZgBkvB .. section: Core and Builtins

Asynchronous comprehensions are now allowed inside comprehensions in asynchronous functions. Outer comprehensions implicitly become asynchronous.

.. bpo: 45371 .. date: 2021-10-05-11-03-48 .. nonce: NOwcDJ .. section: Library

Fix clang rpath issue in distutils. The UnixCCompiler now uses correct clang option to add a runtime library directory (rpath) to a shared library.

.. bpo: 45329 .. date: 2021-10-01-13-09-53 .. nonce: 9iMYaO .. section: Library

Fix freed memory access in :class:pyexpat.xmlparser when building it with an installed expat library <= 2.2.0.

.. bpo: 41710 .. date: 2021-09-30-23-00-18 .. nonce: svuloZ .. section: Library

On Unix, if the sem_clockwait() function is available in the C library (glibc 2.30 and newer), the :meth:threading.Lock.acquire method now uses the monotonic clock (:const:time.CLOCK_MONOTONIC) for the timeout, rather than using the system clock (:const:time.CLOCK_REALTIME), to not be affected by system clock changes. Patch by Victor Stinner.

.. bpo: 1596321 .. date: 2021-09-24-17-20-23 .. nonce: 3nhPUk .. section: Library

Fix the :func:threading._shutdown function when the :mod:threading module was imported first from a thread different than the main thread: no longer log an error at Python exit.

.. bpo: 45274 .. date: 2021-09-23-22-17-26 .. nonce: gPpa4E .. section: Library

Fix a race condition in the :meth:Thread.join() <threading.Thread.join> method of the :mod:threading module. If the function is interrupted by a signal and the signal handler raises an exception, make sure that the thread remains in a consistent state to prevent a deadlock. Patch by Victor Stinner.

.. bpo: 21302 .. date: 2021-09-22-23-56-15 .. nonce: vvQ3Su .. section: Library

In Unix operating systems, :func:time.sleep now uses the nanosleep() function, if clock_nanosleep() is not available but nanosleep() is available. nanosleep() allows to sleep with nanosecond precision.

.. bpo: 21302 .. date: 2021-09-20-22-46-40 .. nonce: h56430 .. section: Library

On Windows, :func:time.sleep now uses a waitable timer which has a resolution of 100 nanoseconds (10\ :sup:-7 seconds). Previously, it had a resolution of 1 millisecond (10\ :sup:-3 seconds). Patch by Benjamin Szőke and Victor Stinner.

.. bpo: 45238 .. date: 2021-09-18-16-56-33 .. nonce: Hng_9V .. section: Library

Fix :meth:unittest.IsolatedAsyncioTestCase.debug: it runs now asynchronous methods and callbacks.

.. bpo: 36674 .. date: 2021-09-18-13-14-57 .. nonce: a2k5Zb .. section: Library

:meth:unittest.TestCase.debug raises now a :class:unittest.SkipTest if the class or the test method are decorated with the skipping decorator.

.. bpo: 45235 .. date: 2021-09-17-16-55-37 .. nonce: sXnmPA .. section: Library

Fix an issue where argparse would not preserve values in a provided namespace when using a subparser with defaults.

.. bpo: 45183 .. date: 2021-09-17-15-58-53 .. nonce: Vv_vch .. section: Library

Have zipimport.zipimporter.find_spec() not raise an exception when the underlying zip file has been deleted and the internal cache has been reset via invalidate_cache().

.. bpo: 45234 .. date: 2021-09-17-11-20-55 .. nonce: qUcTVt .. section: Library

Fixed a regression in :func:~shutil.copyfile, :func:~shutil.copy, :func:~shutil.copy2 raising :exc:FileNotFoundError when source is a directory, which should raise :exc:IsADirectoryError

.. bpo: 45228 .. date: 2021-09-17-09-59-33 .. nonce: WV1dcT .. section: Library

Fix stack buffer overflow in parsing J1939 network address.

.. bpo: 45225 .. date: 2021-09-16-19-02-14 .. nonce: xmKV4i .. section: Library

use map function instead of genexpr in capwords.

.. bpo: 42135 .. date: 2021-09-13-19-32-58 .. nonce: 1ZAHqR .. section: Library

Fix typo: importlib.find_loader is really slated for removal in Python 3.12 not 3.10, like the others in PR 25169.

Patch by Hugo van Kemenade.

.. bpo: 20524 .. date: 2021-09-13-14-59-01 .. nonce: PMQ1Fh .. section: Library

Improves error messages on .format() operation for str, float, int, and complex. New format now shows the problematic pattern and the object type.

.. bpo: 45168 .. date: 2021-09-13-14-28-49 .. nonce: Z1mfW4 .. section: Library

Change :func:dis.dis output to omit op arg values that cannot be resolved due to co_consts, co_names etc not being provided. Previously the oparg itself was repeated in the value field, which is not useful and can be confusing.

.. bpo: 21302 .. date: 2021-09-11-18-44-40 .. nonce: QxHRpR .. section: Library

In Unix operating systems, :func:time.sleep now uses the clock_nanosleep() function, if available, which allows to sleep for an interval specified with nanosecond precision.

.. bpo: 45173 .. date: 2021-09-11-17-46-20 .. nonce: UptGAn .. section: Library

Remove from the :mod:configparser module: the :class:!SafeConfigParser class, the :attr:!filename property of the :class:~configparser.ParsingError class, the :meth:!readfp method of the :class:~configparser.ConfigParser class, deprecated since Python 3.2.

Patch by Hugo van Kemenade.

.. bpo: 44987 .. date: 2021-09-11-14-41-02 .. nonce: Mt8DiX .. section: Library

Pure ASCII strings are now normalized in constant time by :func:unicodedata.normalize. Patch by Donghee Na.

.. bpo: 35474 .. date: 2021-09-11-10-45-12 .. nonce: tEY3SD .. section: Library

Calling :func:mimetypes.guess_all_extensions with strict=False no longer affects the result of the following call with strict=True. Also, mutating the returned list no longer affects the global state.

.. bpo: 45166 .. date: 2021-09-10-21-35-53 .. nonce: UHipXF .. section: Library

:func:typing.get_type_hints now works with :data:~typing.Final wrapped in :class:~typing.ForwardRef.

.. bpo: 45162 .. date: 2021-09-10-13-20-53 .. nonce: 2Jh-lq .. section: Library

Remove many old deprecated :mod:unittest features:

"fail*" and "assert*" aliases of :class:~unittest.TestCase methods.
Broken from start :class:~unittest.TestCase method assertDictContainsSubset().
Ignored :meth:<unittest.TestLoader.loadTestsFromModule> TestLoader.loadTestsFromModule parameter use_load_tests.
Old alias _TextTestResult of :class:~unittest.TextTestResult.

.. bpo: 38371 .. date: 2021-09-08-13-19-29 .. nonce: y1kEfP .. section: Library

Remove the deprecated split() method of :class:!_tkinter.TkappType. Patch by Erlend E. Aasland.

.. bpo: 20499 .. date: 2021-09-08-01-19-31 .. nonce: tSxx8Y .. section: Library

Improve the speed and accuracy of statistics.pvariance().

.. bpo: 45132 .. date: 2021-09-07-16-33-51 .. nonce: WI9zQY .. section: Library

Remove :meth:~object.__getitem__ methods of :class:xml.dom.pulldom.DOMEventStream, :class:wsgiref.util.FileWrapper and :class:fileinput.FileInput, deprecated since Python 3.9.

Patch by Hugo van Kemenade.

.. bpo: 45129 .. date: 2021-09-07-14-27-39 .. nonce: vXH0gw .. section: Library

Due to significant security concerns, the reuse_address parameter of :meth:asyncio.loop.create_datagram_endpoint, disabled in Python 3.9, is now entirely removed. This is because of the behavior of the socket option SO_REUSEADDR in UDP.

Patch by Hugo van Kemenade.

.. bpo: 45124 .. date: 2021-09-07-09-13-27 .. nonce: Kw5AUs .. section: Library

The bdist_msi command, deprecated in Python 3.9, is now removed.

Use bdist_wheel (wheel packages) instead.

Patch by Hugo van Kemenade.

.. bpo: 30856 .. date: 2021-09-05-21-37-28 .. nonce: jj86y0 .. section: Library

:class:unittest.TestResult methods :meth:~unittest.TestResult.addFailure, :meth:~unittest.TestResult.addError, :meth:~unittest.TestResult.addSkip and :meth:~unittest.TestResult.addSubTest are now called immediately after raising an exception in test or finishing a subtest. Previously they were called only after finishing the test clean up.

.. bpo: 45034 .. date: 2021-09-05-20-33-25 .. nonce: 62NLD5 .. section: Library

Changes how error is formatted for struct.pack with 'H' and 'h' modes and too large / small numbers. Now it shows the actual numeric limits, while previously it was showing arithmetic expressions.

.. bpo: 25894 .. date: 2021-09-05-13-15-08 .. nonce: zjbi2f .. section: Library

:mod:unittest now always reports skipped and failed subtests separately: separate characters in default mode and separate lines in verbose mode. Also the test description is now output for errors in test method, class and module cleanups.

.. bpo: 45081 .. date: 2021-09-02-12-42-25 .. nonce: tOjJ1k .. section: Library

Fix issue when dataclasses that inherit from typing.Protocol subclasses have wrong __init__. Patch provided by Yurii Karabas.

.. bpo: 45085 .. date: 2021-09-02-00-47-14 .. nonce: mMnaDv .. section: Library

The binhex module, deprecated in Python 3.9, is now removed. The following :mod:binascii functions, deprecated in Python 3.9, are now also removed:

a2b_hqx(), b2a_hqx();
rlecode_hqx(), rledecode_hqx().

The :func:binascii.crc_hqx function remains available.

Patch by Victor Stinner.

.. bpo: 40360 .. date: 2021-09-02-00-18-32 .. nonce: 9nmMtB .. section: Library

The :mod:!lib2to3 package is now deprecated and may not be able to parse Python 3.10 or newer. See the :pep:617 (New PEG parser for CPython). Patch by Victor Stinner.

.. bpo: 45075 .. date: 2021-09-01-15-27-00 .. nonce: 9xUpvt .. section: Library

Rename :meth:traceback.StackSummary.format_frame to :meth:traceback.StackSummary.format_frame_summary. This method was added for 3.11 so it was not released yet.

Updated code and docs to better distinguish frame and FrameSummary.

.. bpo: 31299 .. date: 2021-08-30-13-55-09 .. nonce: 9QzjZs .. section: Library

Add option to completely drop frames from a traceback by returning None from a :meth:~traceback.StackSummary.format_frame override.

.. bpo: 41620 .. date: 2021-08-29-14-49-22 .. nonce: WJ6PFL .. section: Library

:meth:~unittest.TestCase.run now always return a :class:~unittest.TestResult instance. Previously it returned None if the test class or method was decorated with a skipping decorator.

.. bpo: 45021 .. date: 2021-08-28-13-00-12 .. nonce: rReeaj .. section: Library

Fix a potential deadlock at shutdown of forked children when using :mod:concurrent.futures module

.. bpo: 43913 .. date: 2021-08-27-23-40-51 .. nonce: Uo1Gt5 .. section: Library

Fix bugs in cleaning up classes and modules in :mod:unittest:

Functions registered with :func:~unittest.addModuleCleanup were not called unless the user defines tearDownModule() in their test module.
Functions registered with :meth:~unittest.TestCase.addClassCleanup were not called if tearDownClass is set to None.
Buffering in :class:~unittest.TestResult did not work with functions registered with addClassCleanup() and addModuleCleanup().
Errors in functions registered with addClassCleanup() and addModuleCleanup() were not handled correctly in buffered and debug modes.
Errors in setUpModule() and functions registered with addModuleCleanup() were reported in wrong order.
And several lesser bugs.

.. bpo: 45030 .. date: 2021-08-27-19-01-23 .. nonce: tAmBbY .. section: Library

Fix integer overflow in pickling and copying the range iterator.

.. bpo: 45001 .. date: 2021-08-26-16-25-48 .. nonce: tn_dKp .. section: Library

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

.. bpo: 45010 .. date: 2021-08-26-09-54-14 .. nonce: Cn23bQ .. section: Library

Remove support of special method __div__ in :mod:unittest.mock. It is not used in Python 3.

.. bpo: 39218 .. date: 2021-08-25-20-18-31 .. nonce: BlO6jW .. section: Library

Improve accuracy of variance calculations by using x*x instead of x**2.

.. bpo: 43613 .. date: 2021-08-25-10-28-49 .. nonce: WkYmI0 .. section: Library

Improve the speed of :func:gzip.compress and :func:gzip.decompress by compressing and decompressing at once in memory instead of in a streamed fashion.

.. bpo: 37596 .. date: 2021-08-23-21-39-59 .. nonce: ojRcwB .. section: Library

Ensure that :class:set and :class:frozenset objects are always :mod:marshalled <marshal> reproducibly.

.. bpo: 44019 .. date: 2021-08-22-13-25-17 .. nonce: BN8HDy .. section: Library

A new function operator.call has been added, such that operator.call(obj, *args, **kwargs) == obj(*args, **kwargs).

.. bpo: 42255 .. date: 2021-08-19-23-49-10 .. nonce: ofe3ms .. section: Library

:class:!webbrowser.MacOSX is deprecated and will be removed in Python 3.13. It is untested and undocumented and also not used by :mod:webbrowser itself. Patch by Donghee Na.

.. bpo: 44955 .. date: 2021-08-19-15-03-54 .. nonce: 1mxFQS .. section: Library

Method :meth:~unittest.TestResult.stopTestRun is now always called in pair with method :meth:~unittest.TestResult.startTestRun for :class:~unittest.TestResult objects implicitly created in :meth:~unittest.TestCase.run. Previously it was not called for test methods and classes decorated with a skipping decorator.

.. bpo: 39039 .. date: 2021-08-18-10-36-14 .. nonce: A63LYh .. section: Library

tarfile.open raises :exc:~tarfile.ReadError when a zlib error occurs during file extraction.

.. bpo: 44935 .. date: 2021-08-17-16-01-44 .. nonce: roUl0G .. section: Library

:mod:subprocess on Solaris now also uses :func:os.posix_spawn for better performance.

.. bpo: 44911 .. date: 2021-08-14-00-55-16 .. nonce: uk3hYk .. section: Library

:class:~unittest.IsolatedAsyncioTestCase will no longer throw an exception while cancelling leaked tasks. Patch by Bar Harel.

.. bpo: 41322 .. date: 2021-08-12-16-22-16 .. nonce: utscTd .. section: Library

Added DeprecationWarning for tests and async tests that return a value!=None (as this may indicate an improperly written test, for example a test written as a generator function).

.. bpo: 44524 .. date: 2021-08-10-16-57-10 .. nonce: dk9QX4 .. section: Library

Make exception message more useful when subclass from typing special form alias. Patch provided by Yurii Karabas.

.. bpo: 38956 .. date: 2021-08-09-13-17-10 .. nonce: owWLNv .. section: Library

:class:argparse.BooleanOptionalAction's default value is no longer printed twice when used with :class:argparse.ArgumentDefaultsHelpFormatter.

.. bpo: 44860 .. date: 2021-08-07-22-51-32 .. nonce: PTvRrU .. section: Library

Fix the posix_user scheme in :mod:sysconfig to not depend on :data:sys.platlibdir.

.. bpo: 44859 .. date: 2021-08-07-17-28-56 .. nonce: CCopjk .. section: Library

Improve error handling in :mod:sqlite3 and raise more accurate exceptions.

:exc:MemoryError is now raised instead of :exc:sqlite3.Warning when memory is not enough for encoding a statement to UTF-8 in Connection.__call__() and Cursor.execute().
:exc:UnicodEncodeError is now raised instead of :exc:sqlite3.Warning when the statement contains surrogate characters in Connection.__call__() and Cursor.execute().
:exc:TypeError is now raised instead of :exc:ValueError for non-string script argument in Cursor.executescript().
:exc:ValueError is now raised for script containing the null character instead of truncating it in Cursor.executescript().
Correctly handle exceptions raised when getting boolean value of the result of the progress handler.
Add many tests covering different corner cases.

.. bpo: 44581 .. date: 2021-08-06-19-15-52 .. nonce: oFDBTB .. section: Library

Upgrade bundled pip to 21.2.3 and setuptools to 57.4.0

.. bpo: 44849 .. date: 2021-08-06-13-00-28 .. nonce: O78F_f .. section: Library

Fix the :func:os.set_inheritable function on FreeBSD 14 for file descriptor opened with the :const:~os.O_PATH flag: ignore the :const:~errno.EBADF error on ioctl(), fallback on the fcntl() implementation. Patch by Victor Stinner.

.. bpo: 44605 .. date: 2021-08-06-09-43-50 .. nonce: q4YSBZ .. section: Library

The @functools.total_ordering() decorator now works with metaclasses.

.. bpo: 44524 .. date: 2021-08-05-18-20-17 .. nonce: 9T1tfe .. section: Library

Fixed an issue wherein the __name__ and __qualname__ attributes of subscribed specialforms could be None.

.. bpo: 44839 .. date: 2021-08-05-14-59-39 .. nonce: MURNL9 .. section: Library

:class:MemoryError raised in user-defined functions will now produce a MemoryError in :mod:sqlite3. :class:OverflowError will now be converted to :class:~sqlite3.DataError. Previously :class:~sqlite3.OperationalError was produced in these cases.

.. bpo: 44822 .. date: 2021-08-04-12-29-00 .. nonce: zePNXA .. section: Library

:mod:sqlite3 user-defined functions and aggregators returning :class:strings <str> with embedded NUL characters are no longer truncated. Patch by Erlend E. Aasland.

.. bpo: 44801 .. date: 2021-08-03-20-37-45 .. nonce: i49Aug .. section: Library

Ensure that the :class:~typing.ParamSpec variable in Callable can only be substituted with a parameters expression (a list of types, an ellipsis, ParamSpec or Concatenate).

.. bpo: 44806 .. date: 2021-08-02-14-37-32 .. nonce: wOW_Qn .. section: Library

Non-protocol subclasses of :class:typing.Protocol ignore now the __init__ method inherited from protocol base classes.

.. bpo: 27275 .. date: 2021-08-01-19-49-09 .. nonce: QsvE0k .. section: Library

:meth:collections.OrderedDict.popitem and :meth:collections.OrderedDict.pop no longer call __getitem__ and __delitem__ methods of the OrderedDict subclasses.

.. bpo: 44793 .. date: 2021-07-31-20-28-20 .. nonce: woaQSg .. section: Library

Fix checking the number of arguments when subscribe a generic type with ParamSpec parameter.

.. bpo: 44784 .. date: 2021-07-31-08-45-31 .. nonce: fIMIDS .. section: Library

In importlib.metadata tests, override warnings behavior under expected DeprecationWarnings (importlib_metadata 4.6.3).

.. bpo: 44667 .. date: 2021-07-30-23-27-30 .. nonce: tu0Xrv .. section: Library

The :func:tokenize.tokenize doesn't incorrectly generate a NEWLINE token if the source doesn't end with a new line character but the last line is a comment, as the function is already generating a NL token. Patch by Pablo Galindo

.. bpo: 44771 .. date: 2021-07-28-22-53-18 .. nonce: BvLdnU .. section: Library

Added importlib.simple module implementing adapters from a low-level resources reader interface to a TraversableResources interface. Legacy API (path, contents, ...) is now supported entirely by the .files() API with a compatibility shim supplied for resource loaders without that functionality. Feature parity with importlib_resources 5.2.

.. bpo: 44752 .. date: 2021-07-27-22-11-29 .. nonce: _bvbrZ .. section: Library

:mod:rcompleter does not call :func:getattr on :class:property objects to avoid the side-effect of evaluating the corresponding method.

.. bpo: 44747 .. date: 2021-07-27-12-06-19 .. nonce: epUzZz .. section: Library

Refactor usage of sys._getframe in typing module. Patch provided by Yurii Karabas.

.. bpo: 42378 .. date: 2021-07-25-08-17-55 .. nonce: WIhUZK .. section: Library

Fixes the issue with log file being overwritten when :class:logging.FileHandler is used in :mod:atexit with filemode set to 'w'. Note this will cause the message in atexit not being logged if the log stream is already closed due to shutdown of logging.

.. bpo: 44720 .. date: 2021-07-24-02-17-59 .. nonce: shU5Qm .. section: Library

weakref.proxy objects referencing non-iterators now raise TypeError rather than dereferencing the null tp_iternext slot and crashing.

.. bpo: 44704 .. date: 2021-07-21-23-16-30 .. nonce: iqHLxQ .. section: Library

The implementation of collections.abc.Set._hash() now matches that of frozenset.__hash__().

.. bpo: 44666 .. date: 2021-07-21-10-43-22 .. nonce: CEThkv .. section: Library

Fixed issue in :func:compileall.compile_file when sys.stdout is redirected. Patch by Stefan Hölzl.

.. bpo: 44688 .. date: 2021-07-20-23-28-26 .. nonce: buFgz3 .. section: Library

:meth:sqlite3.Connection.create_collation now accepts non-ASCII collation names. Patch by Erlend E. Aasland.

.. bpo: 44690 .. date: 2021-07-20-22-03-24 .. nonce: tV7Zjg .. section: Library

Adopt binacii.a2b_base64's strict mode in base64.b64decode.

.. bpo: 42854 .. date: 2021-07-20-21-51-35 .. nonce: ThuDMI .. section: Library

Fixed a bug in the :mod:!_ssl module that was throwing :exc:OverflowError when using :meth:!_ssl._SSLSocket.write and :meth:!_ssl._SSLSocket.read for a big value of the len parameter. Patch by Pablo Galindo.

.. bpo: 44686 .. date: 2021-07-20-19-35-49 .. nonce: ucCGhu .. section: Library

Replace unittest.mock._importer with pkgutil.resolve_name.

.. bpo: 44353 .. date: 2021-07-20-18-34-16 .. nonce: ATuYq4 .. section: Library

Make NewType.__call__ faster by implementing it in C. Patch provided by Yurii Karabas.

.. bpo: 44682 .. date: 2021-07-20-00-11-47 .. nonce: 3m2qVV .. section: Library

Change the :mod:pdb commands directive to disallow setting commands for an invalid breakpoint and to display an appropriate error.

.. bpo: 44353 .. date: 2021-07-19-22-43-15 .. nonce: HF81_Q .. section: Library

Refactor typing.NewType from function into callable class. Patch provided by Yurii Karabas.

.. bpo: 44678 .. date: 2021-07-19-18-45-00 .. nonce: YMEAu0 .. section: Library

Added a separate error message for discontinuous padding in binascii.a2b_base64 strict mode.

.. bpo: 44524 .. date: 2021-07-19-14-04-42 .. nonce: Nbf2JC .. section: Library

Add missing __name__ and __qualname__ attributes to typing module classes. Patch provided by Yurii Karabas.

.. bpo: 40897 .. date: 2021-07-16-13-40-31 .. nonce: aveAre .. section: Library

Give priority to using the current class constructor in :func:inspect.signature. Patch by Weipeng Hong.

.. bpo: 44638 .. date: 2021-07-16-08-57-27 .. nonce: EwYKne .. section: Library

Add a reference to the zipp project and hint as to how to use it.

.. bpo: 44648 .. date: 2021-07-15-16-51-32 .. nonce: 2o49TB .. section: Library

Fixed wrong error being thrown by :func:inspect.getsource when examining a class in the interactive session. Instead of :exc:TypeError, it should be :exc:OSError with appropriate error message.

.. bpo: 44608 .. date: 2021-07-13-09-01-33 .. nonce: R3IcM1 .. section: Library

Fix memory leak in :func:!_tkinter._flatten if it is called with a sequence or set, but not list or tuple.

.. bpo: 44594 .. date: 2021-07-12-10-32-48 .. nonce: eEa5zi .. section: Library

Fix an edge case of :class:ExitStack and :class:AsyncExitStack exception chaining. They will now match with block behavior when __context__ is explicitly set to None when the exception is in flight.

.. bpo: 42799 .. date: 2021-07-10-19-55-13 .. nonce: ad4tq8 .. section: Library

In :mod:fnmatch, the cache size for compiled regex patterns (:func:functools.lru_cache) was bumped up from 256 to 32768, affecting functions: :func:fnmatch.fnmatch, :func:fnmatch.fnmatchcase, :func:fnmatch.filter.

.. bpo: 41928 .. date: 2021-07-09-07-14-37 .. nonce: Q1jMrr .. section: Library

Update :func:shutil.copyfile to raise :exc:FileNotFoundError instead of confusing :exc:IsADirectoryError when a path ending with a :const:os.path.sep does not exist; :func:shutil.copy and :func:shutil.copy2 are also affected.

.. bpo: 44569 .. date: 2021-07-08-12-22-54 .. nonce: KZ02v9 .. section: Library

Added the :func:StackSummary.format_frame function in :mod:traceback. This allows users to customize the way individual lines are formatted in tracebacks without re-implementing logic to handle recursive tracebacks.

.. bpo: 44566 .. date: 2021-07-05-18-13-25 .. nonce: o51Bd1 .. section: Library

handle StopIteration subclass raised from @contextlib.contextmanager generator

.. bpo: 44558 .. date: 2021-07-04-21-16-53 .. nonce: cm7Slv .. section: Library

Make the implementation consistency of :func:~operator.indexOf between C and Python versions. Patch by Donghee Na.

.. bpo: 41249 .. date: 2021-07-04-11-33-34 .. nonce: sHdwBE .. section: Library

Fixes TypedDict to work with typing.get_type_hints() and postponed evaluation of annotations across modules.

.. bpo: 44554 .. date: 2021-07-02-18-17-56 .. nonce: aBUmJo .. section: Library

Refactor argument processing in :func:pdb.main to simplify detection of errors in input loading and clarify behavior around module or script invocation.

.. bpo: 34798 .. date: 2021-06-30-13-29-49 .. nonce: t7FCa0 .. section: Library

Break up paragraph about :class:pprint.PrettyPrinter construction parameters to make it easier to read.

.. bpo: 44539 .. date: 2021-06-30-11-34-35 .. nonce: nP0Xi4 .. section: Library

Added support for recognizing JPEG files without JFIF or Exif markers.

.. bpo: 44461 .. date: 2021-06-29-21-17-17 .. nonce: acqRnV .. section: Library

Fix bug with :mod:pdb's handling of import error due to a package which does not have a __main__ module

.. bpo: 43625 .. date: 2021-06-29-07-27-08 .. nonce: ZlAxhp .. section: Library

Fix a bug in the detection of CSV file headers by :meth:csv.Sniffer.has_header and improve documentation of same.

.. bpo: 44516 .. date: 2021-06-26-12-27-14 .. nonce: BVyX_y .. section: Library

Update vendored pip to 21.1.3

.. bpo: 42892 .. date: 2021-06-24-19-16-20 .. nonce: qvRNhI .. section: Library

Fixed an exception thrown while parsing a malformed multipart email by :class:email.message.EmailMessage.

.. bpo: 44468 .. date: 2021-06-23-19-02-00 .. nonce: -klV5- .. section: Library

:func:typing.get_type_hints now finds annotations in classes and base classes with unexpected __module__. Previously, it skipped those MRO elements.

.. bpo: 44491 .. date: 2021-06-23-01-33-01 .. nonce: tiOlr5 .. section: Library

Allow clearing the :mod:sqlite3 authorizer callback by passing :const:None to :meth:~sqlite3.Connection.set_authorizer. Patch by Erlend E. Aasland.

.. bpo: 43977 .. date: 2021-06-22-16-45-48 .. nonce: bamAGF .. section: Library

Set the proper :c:macro:Py_TPFLAGS_MAPPING and :c:macro:Py_TPFLAGS_SEQUENCE flags for subclasses created before a parent has been registered as a :class:collections.abc.Mapping or :class:collections.abc.Sequence.

.. bpo: 44482 .. date: 2021-06-22-08-43-04 .. nonce: U9GznK .. section: Library

Fix very unlikely resource leak in :mod:glob in alternate Python implementations.

.. bpo: 44466 .. date: 2021-06-21-12-43-04 .. nonce: NSm6mv .. section: Library

The :mod:faulthandler module now detects if a fatal error occurs during a garbage collector collection. Patch by Victor Stinner.

.. bpo: 44471 .. date: 2021-06-21-10-46-58 .. nonce: 2QjXv_ .. section: Library

A :exc:TypeError is now raised instead of an :exc:AttributeError in :meth:contextlib.ExitStack.enter_context and :meth:contextlib.AsyncExitStack.enter_async_context for objects which do not support the :term:context manager or :term:asynchronous context manager protocols correspondingly.

.. bpo: 44404 .. date: 2021-06-20-19-01-11 .. nonce: McfrYB .. section: Library

:mod:tkinter's after() method now supports callables without the __name__ attribute.

.. bpo: 41546 .. date: 2021-06-20-14-03-18 .. nonce: lO1jXU .. section: Library

Make :mod:pprint (like the builtin print) not attempt to write to stdout when it is None.

.. bpo: 44458 .. date: 2021-06-20-07-14-46 .. nonce: myqCQ0 .. section: Library

BUFFER_BLOCK_SIZE is now declared static, to avoid linking collisions when bz2, lmza or zlib are statically linked.

.. bpo: 44464 .. date: 2021-06-19-21-52-27 .. nonce: U2oa-a .. section: Library

Remove exception for flake8 in deprecated importlib.metadata interfaces. Sync with importlib_metadata 4.6.

.. bpo: 44446 .. date: 2021-06-17-22-39-34 .. nonce: qwdRic .. section: Library

Take into account that lineno might be None in :class:traceback.FrameSummary.

.. bpo: 44439 .. date: 2021-06-17-15-01-51 .. nonce: 1S7QhT .. section: Library

Fix in :meth:bz2.BZ2File.write / :meth:lzma.LZMAFile.write methods, when the input data is an object that supports the buffer protocol, the file length may be wrong.

.. bpo: 44434 .. date: 2021-06-16-16-52-14 .. nonce: SQS4Pg .. section: Library

_thread.start_new_thread() no longer calls PyThread_exit_thread() explicitly at the thread exit, the call was redundant. On Linux with the glibc, pthread_exit() aborts the whole process if dlopen() fails to open libgcc_s.so file (ex: EMFILE error). Patch by Victor Stinner.

.. bpo: 42972 .. date: 2021-06-15-13-51-25 .. nonce: UnyYo1 .. section: Library

The _thread.RLock type now fully implement the GC protocol: add a traverse function and the :c:macro:Py_TPFLAGS_HAVE_GC flag. Patch by Victor Stinner.

.. bpo: 44422 .. date: 2021-06-14-23-28-17 .. nonce: BlWOgv .. section: Library

The :func:threading.enumerate function now uses a reentrant lock to prevent a hang on reentrant call. Patch by Victor Stinner.

.. bpo: 38291 .. date: 2021-06-14-14-19-11 .. nonce: ee4cSX .. section: Library

Importing typing.io or typing.re now prints a DeprecationWarning.

.. bpo: 37880 .. date: 2021-06-13-00-16-56 .. nonce: 5bTrkw .. section: Library

argparse actions store_const and append_const each receive a default value of None when the const kwarg is not provided. Previously, this raised a :exc:TypeError.

.. bpo: 44389 .. date: 2021-06-12-22-58-20 .. nonce: WTRnoC .. section: Library

Fix deprecation of :data:ssl.OP_NO_TLSv1_3

.. bpo: 27827 .. date: 2021-06-12-21-25-35 .. nonce: TMWh1i .. section: Library

:meth:!pathlib.PureWindowsPath.is_reserved now identifies a greater range of reserved filenames, including those with trailing spaces or colons.

.. bpo: 44395 .. date: 2021-06-12-10-08-14 .. nonce: PcW6Sx .. section: Library

Fix :meth:~email.message.MIMEPart.as_string to pass unixfrom properly. Patch by Donghee Na.

.. bpo: 34266 .. date: 2021-06-10-21-53-46 .. nonce: k3fxnm .. section: Library

Handle exceptions from parsing the arg of :mod:pdb's run/restart command.

.. bpo: 44362 .. date: 2021-06-10-20-07-32 .. nonce: oVOMfd .. section: Library

Improve :mod:ssl module's deprecation messages, error reporting, and documentation for deprecations.

.. bpo: 44342 .. date: 2021-06-10-15-06-47 .. nonce: qqkGlj .. section: Library

[Enum] Change pickling from by-value to by-name.

.. bpo: 44356 .. date: 2021-06-10-08-35-38 .. nonce: 6oDFhO .. section: Library

[Enum] Allow multiple data-type mixins if they are all the same.

.. bpo: 44351 .. date: 2021-06-10-07-26-12 .. nonce: rvyf2v .. section: Library

Restore back :func:parse_makefile in distutils.sysconfig because it behaves differently than the similar implementation in :mod:sysconfig.

.. bpo: 35800 .. date: 2021-06-09-10-08-32 .. nonce: 3hmkWw .. section: Library

:class:!smtpd.MailmanProxy is now removed as it is unusable without an external module, mailman. Patch by Donghee Na.

.. bpo: 44357 .. date: 2021-06-09-08-32-39 .. nonce: 70Futb .. section: Library

Added a function that returns cube root of the given number :func:math.cbrt

.. bpo: 44339 .. date: 2021-06-08-17-47-38 .. nonce: 9JwMSc .. section: Library

Change math.pow(±0.0, -math.inf) to return inf instead of raising ValueError. This brings the special-case handling of math.pow into compliance with the IEEE 754 standard.

.. bpo: 44242 .. date: 2021-06-07-10-26-14 .. nonce: MKeMCQ .. section: Library

Remove missing flag check from Enum creation and move into a verify decorator.

.. bpo: 44246 .. date: 2021-05-31-11-34-56 .. nonce: yHAkF0 .. section: Library

In importlib.metadata, restore compatibility in the result from Distribution.entry_points (EntryPoints) to honor expectations in older implementations and issuing deprecation warnings for these cases: A. EntryPoints objects are once again mutable, allowing for sort() and other list-based mutation operations. Avoid deprecation warnings by casting to a mutable sequence (e.g. list(dist.entry_points).sort()). B. EntryPoints results once again allow for access by index. To avoid deprecation warnings, cast the result to a Sequence first (e.g. tuple(dist.entry_points)[0]).

.. bpo: 44246 .. date: 2021-05-31-11-28-03 .. nonce: nhmt-v .. section: Library

In importlib.metadata.entry_points, de-duplication of distributions no longer requires loading the full metadata for PathDistribution objects, improving entry point loading performance by ~10x.

.. bpo: 43858 .. date: 2021-05-31-04-51-02 .. nonce: r7LOu6 .. section: Library

Added a function that returns a copy of a dict of logging levels: :func:logging.getLevelNamesMapping

.. bpo: 44260 .. date: 2021-05-30-13-32-09 .. nonce: ROEbVd .. section: Library

The :class:random.Random constructor no longer reads system entropy without need.

.. bpo: 44254 .. date: 2021-05-29-01-05-43 .. nonce: f06xDm .. section: Library

On Mac, give turtledemo button text a color that works on both light or dark background. Programmers cannot control the latter.

.. bpo: 44258 .. date: 2021-05-28-09-43-33 .. nonce: nh5F7R .. section: Library

Support PEP 515 for Fraction's initialization from string.

.. bpo: 44235 .. date: 2021-05-26-22-04-40 .. nonce: qFBYpp .. section: Library

Remove deprecated functions in the :mod:gettext. Patch by Donghee Na.

.. bpo: 38693 .. date: 2021-05-26-14-50-06 .. nonce: NkMacJ .. section: Library

Prefer f-strings to .format in importlib.resources.

.. bpo: 33693 .. date: 2021-05-26-13-34-37 .. nonce: 3okzdo .. section: Library

Importlib.metadata now prefers f-strings to .format.

.. bpo: 44241 .. date: 2021-05-26-13-15-51 .. nonce: TBqej8 .. section: Library

Incorporate minor tweaks from importlib_metadata 4.1: SimplePath protocol, support for Metadata 2.2.

.. bpo: 43216 .. date: 2021-05-25-23-26-38 .. nonce: xTUyyX .. section: Library

Remove the :deco:asyncio.coroutine :term:decorator enabling legacy generator-based coroutines to be compatible with async/await code; remove :class:asyncio.coroutines.CoroWrapper used for wrapping legacy coroutine objects in the debug mode. The decorator has been deprecated since Python 3.8 and the removal was initially scheduled for Python 3.10. Patch by Illia Volochii.

.. bpo: 44210 .. date: 2021-05-21-21-23-43 .. nonce: 5afQ3K .. section: Library

Make importlib.metadata._meta.PackageMetadata public.

.. bpo: 43643 .. date: 2021-05-21-12-12-35 .. nonce: GWnmcF .. section: Library

Declare readers.MultiplexedPath.name as a property per the spec.

.. bpo: 27334 .. date: 2021-05-18-00-17-21 .. nonce: 32EJZi .. section: Library

The :mod:sqlite3 context manager now performs a rollback (thus releasing the database lock) if commit failed. Patch by Luca Citi and Erlend E. Aasland.

.. bpo: 4928 .. date: 2021-05-17-21-05-06 .. nonce: Ot2yjO .. section: Library

Documented existing behavior on POSIX: NamedTemporaryFiles are not deleted when creating process is killed with SIGKILL

.. bpo: 44154 .. date: 2021-05-17-07-24-24 .. nonce: GRI5bf .. section: Library

Optimize :class:fractions.Fraction pickling for large components.

.. bpo: 33433 .. date: 2021-05-16-17-48-24 .. nonce: MyzO71 .. section: Library

For IPv4 mapped IPv6 addresses (:rfc:4291 Section 2.5.5.2), the :mod:ipaddress.IPv6Address.is_private check is deferred to the mapped IPv4 address. This solves a bug where public mapped IPv4 addresses were considered private by the IPv6 check.

.. bpo: 44150 .. date: 2021-05-16-11-57-38 .. nonce: xAhhik .. section: Library

Add optional weights argument to statistics.fmean().

.. bpo: 44142 .. date: 2021-05-16-02-24-23 .. nonce: t-XU8k .. section: Library

:func:ast.unparse will now drop the redundant parentheses when tuples used as assignment targets (e.g in for loops).

.. bpo: 44145 .. date: 2021-05-16-00-00-38 .. nonce: ko5SJ7 .. section: Library

:mod:hmac computations were not releasing the GIL while calling the OpenSSL HMAC_Update C API (a new feature in 3.9). This unintentionally prevented parallel computation as other :mod:hashlib algorithms support.

.. bpo: 44095 .. date: 2021-05-14-16-06-02 .. nonce: v_pLwY .. section: Library

:class:zipfile.Path now supports :attr:zipfile.Path.stem, :attr:zipfile.Path.suffixes, and :attr:zipfile.Path.suffix attributes.

.. bpo: 44077 .. date: 2021-05-13-19-44-38 .. nonce: 04b2a4 .. section: Library

It's now possible to receive the type of service (ToS), a.k.a. differentiated services (DS), a.k.a. differentiated services code point (DSCP) and explicit congestion notification (ECN) IP header fields with socket.IP_RECVTOS.

.. bpo: 37788 .. date: 2021-05-13-19-07-28 .. nonce: adeFcf .. section: Library

Fix a reference leak when a Thread object is never joined.

.. bpo: 38908 .. date: 2021-05-12-16-43-21 .. nonce: nM2_rO .. section: Library

Subclasses of typing.Protocol which only have data variables declared will now raise a TypeError when checked with isinstance unless they are decorated with :func:runtime_checkable. Previously, these checks passed silently. Patch provided by Yurii Karabas.

.. bpo: 44098 .. date: 2021-05-10-17-45-00 .. nonce: _MoxuZ .. section: Library

typing.ParamSpec will no longer be found in the __parameters__ of most :mod:typing generics except in valid use locations specified by :pep:612. This prevents incorrect usage like typing.List[P][int]. This change means incorrect usage which may have passed silently in 3.10 beta 1 and earlier will now error.

.. bpo: 44089 .. date: 2021-05-09-22-52-34 .. nonce: IoANsN .. section: Library

Allow subclassing csv.Error in 3.10 (it was allowed in 3.9 and earlier but was disallowed in early versions of 3.10).

.. bpo: 44081 .. date: 2021-05-09-03-26-31 .. nonce: A-Mrto .. section: Library

:func:ast.unparse now doesn't use redundant spaces to separate lambda and the : if there are no parameters.

.. bpo: 44061 .. date: 2021-05-07-08-39-23 .. nonce: MvElG6 .. section: Library

Fix regression in previous release when calling :func:pkgutil.iter_modules with a list of :class:pathlib.Path objects

.. bpo: 44059 .. date: 2021-05-06-16-01-55 .. nonce: GF5r6O .. section: Library

.. bpo: 36515 .. date: 2021-05-05-11-44-49 .. nonce: uOSa3q .. section: Library

The :mod:hashlib module no longer does unaligned memory accesses when compiled for ARM platforms.

.. bpo: 40465 .. date: 2021-05-03-19-59-14 .. nonce: 1tB4Y0 .. section: Library

Remove random module features deprecated in Python 3.9.

.. bpo: 44018 .. date: 2021-05-03-10-07-43 .. nonce: VDyW8f .. section: Library

random.seed() no longer mutates bytearray inputs.

.. bpo: 38352 .. date: 2021-05-02-13-54-25 .. nonce: N9MlhV .. section: Library

Add IO, BinaryIO, TextIO, Match, and Pattern to typing.__all__. Patch by Jelle Zijlstra.

.. bpo: 44002 .. date: 2021-05-01-15-43-37 .. nonce: KLT_wd .. section: Library

:mod:urllib.parse now uses :func:functool.lru_cache for its internal URL splitting and quoting caches instead of rolling its own like its the '90s.

The undocumented internal :mod:urllib.parse Quoted class API is now deprecated, for removal in 3.14.

.. bpo: 43972 .. date: 2021-04-30-16-58-24 .. nonce: Y2r9lg .. section: Library

When :class:http.server.SimpleHTTPRequestHandler sends a 301 (Moved Permanently) for a directory path not ending with /, add a Content-Length: 0 header. This improves the behavior for certain clients.

.. bpo: 28528 .. date: 2021-04-29-00-48-00 .. nonce: JLAVWj .. section: Library

Fix a bug in :mod:pdb where :meth:~pdb.Pdb.checkline raises :exc:AttributeError if it is called after :meth:~pdb.Pdb.reset.

.. bpo: 43853 .. date: 2021-04-15-12-02-17 .. nonce: XXCVAp .. section: Library

Improved string handling for :mod:sqlite3 user-defined functions and aggregates:

It is now possible to pass strings with embedded null characters to UDFs
Conversion failures now correctly raise :exc:MemoryError

Patch by Erlend E. Aasland.

.. bpo: 43666 .. date: 2021-03-30-08-39-08 .. nonce: m72tlH .. section: Library

AIX: Lib/_aix_support.get_platform() may fail in an AIX WPAR. The fileset bos.rte appears to have a builddate in both LPAR and WPAR so this fileset is queried rather than bos.mp64. To prevent a similar situation (no builddate in ODM) a value (9988) sufficient for completing a build is provided. Patch by M Felt.

.. bpo: 43650 .. date: 2021-03-29-00-23-30 .. nonce: v01tic .. section: Library

Fix :exc:MemoryError in :func:shutil.unpack_archive which fails inside :func:shutil._unpack_zipfile on large files. Patch by Igor Bolshakov.

.. bpo: 43612 .. date: 2021-03-24-09-40-02 .. nonce: vMGZ4y .. section: Library

:func:zlib.compress now accepts a wbits parameter which allows users to compress data as a raw deflate block without zlib headers and trailers in one go. Previously this required instantiating a zlib.compressobj. It also provides a faster alternative to gzip.compress when wbits=31 is used.

.. bpo: 43392 .. date: 2021-03-03-13-32-37 .. nonce: QQumou .. section: Library

:func:importlib._bootstrap._find_and_load now implements a two-step check to avoid locking when modules have been already imported and are ready. This improves performance of repeated calls to :func:importlib.import_module and :func:importlib.__import__.

.. bpo: 43318 .. date: 2021-02-25-08-32-06 .. nonce: bZJw6V .. section: Library

Fix a bug where :mod:pdb does not always echo cleared breakpoints.

.. bpo: 43234 .. date: 2021-02-15-22-14-31 .. nonce: F-vKAT .. section: Library

Prohibit passing non-:class:concurrent.futures.ThreadPoolExecutor executors to :meth:loop.set_default_executor following a deprecation in Python 3.8. Patch by Illia Volochii.

.. bpo: 43232 .. date: 2021-02-15-21-17-46 .. nonce: awc4yZ .. section: Library

Prohibit previously deprecated potentially disruptive operations on :class:asyncio.trsock.TransportSocket. Patch by Illia Volochii.

.. bpo: 30077 .. date: 2021-02-04-23-16-03 .. nonce: v6TqAi .. section: Library

Added support for Apple's aifc/sowt pseudo-compression

.. bpo: 42971 .. date: 2021-02-02-20-11-14 .. nonce: OpVoFu .. section: Library

Add definition of errno.EQFULL for platforms that define this constant (such as macOS).

.. bpo: 43086 .. date: 2021-01-31-18-24-54 .. nonce: 2_P-SH .. section: Library

Added a new optional :code:strict_mode parameter to binascii.a2b_base64. When :code:scrict_mode is set to :code:True, the a2b_base64 function will accept only valid base64 content. More details about what "valid base64 content" is, can be found in the function's documentation.

.. bpo: 43024 .. date: 2021-01-25-21-24-55 .. nonce: vAUrIi .. section: Library

Improve the help signature of :func:traceback.print_exception, :func:traceback.format_exception and :func:traceback.format_exception_only.

.. bpo: 33809 .. date: 2021-01-16-18-36-00 .. nonce: BiMK6V .. section: Library

Add the :meth:traceback.TracebackException.print method which prints the formatted exception information.

.. bpo: 42862 .. date: 2021-01-13-00-02-44 .. nonce: Z6ACLN .. section: Library

:mod:sqlite3 now utilizes :meth:functools.lru_cache to implement the connection statement cache. As a small optimisation, the default statement cache size has been increased from 100 to 128. Patch by Erlend E. Aasland.

.. bpo: 41818 .. date: 2020-12-08-01-08-58 .. nonce: zO8vV7 .. section: Library

Soumendra Ganguly: add termios.tcgetwinsize(), termios.tcsetwinsize().

.. bpo: 40497 .. date: 2020-10-18-09-42-53 .. nonce: CRz2sG .. section: Library

:meth:subprocess.check_output now raises :exc:ValueError when the invalid keyword argument check is passed by user code. Previously such use would fail later with a :exc:TypeError. Patch by Rémi Lapeyre.

.. bpo: 37449 .. date: 2020-10-11-20-23-48 .. nonce: f-t3V6 .. section: Library

ensurepip now uses importlib.resources.files() traversable APIs

.. bpo: 40956 .. date: 2020-10-01-21-46-34 .. nonce: _tvsZ7 .. section: Library

Use Argument Clinic in :mod:sqlite3. Patches by Erlend E. Aasland.

.. bpo: 41730 .. date: 2020-09-10-07-23-24 .. nonce: DyKFi9 .. section: Library

DeprecationWarning is now raised when importing :mod:tkinter.tix, which has been deprecated in documentation since Python 3.6.

.. bpo: 20684 .. date: 2020-07-30-14-37-15 .. nonce: qV35GU .. section: Library

Remove unused _signature_get_bound_param function from :mod:inspect - by Anthony Sottile.

.. bpo: 41402 .. date: 2020-07-26-18-17-30 .. nonce: YRkVkp .. section: Library

Fix :meth:email.message.EmailMessage.set_content when called with binary data and 7bit content transfer encoding.

.. bpo: 32695 .. date: 2020-07-13-23-46-59 .. nonce: tTqqXe .. section: Library

The compresslevel and preset keyword arguments of :func:tarfile.open are now both documented and tested.

.. bpo: 41137 .. date: 2020-07-01-17-42-41 .. nonce: AnqbP- .. section: Library

Use utf-8 encoding while reading .pdbrc files. Patch by Srinivas Reddy Thatiparthy

.. bpo: 24391 .. date: 2020-05-30-10-48-04 .. nonce: ZCTnhX .. section: Library

Improved reprs of :mod:threading synchronization objects: :class:~threading.Semaphore, :class:~threading.BoundedSemaphore, :class:~threading.Event and :class:~threading.Barrier.

.. bpo: 5846 .. date: 2020-05-25-23-58-29 .. nonce: O9BIfm .. section: Library

Deprecated the following :mod:unittest functions, scheduled for removal in Python 3.13:

:func:!findTestCases
:func:!makeSuite
:func:!getTestCaseNames

Use :class:~unittest.TestLoader methods instead:

:meth:unittest.TestLoader.loadTestsFromModule
:meth:unittest.TestLoader.loadTestsFromTestCase
:meth:unittest.TestLoader.getTestCaseNames

Patch by Erlend E. Aasland.

.. bpo: 40563 .. date: 2020-05-21-01-42-32 .. nonce: fDn5bP .. section: Library

Support pathlike objects on dbm/shelve. Patch by Hakan Çelik and Henry-Joseph Audéoud.

.. bpo: 34990 .. date: 2020-04-24-20-39-38 .. nonce: 3SmL9M .. section: Library

Fixed a Y2k38 bug in the compileall module where it would fail to compile files with a modification time after the year 2038.

.. bpo: 39549 .. date: 2020-02-03-21-18-31 .. nonce: l4a8uH .. section: Library

Whereas the code for reprlib.Repr had previously used a hardcoded string value of '...', this PR updates it to use of a “fillvalue” attribute, whose value defaults to '...' and can be reset in either individual reprlib.Repr instances or in subclasses thereof.

.. bpo: 37022 .. date: 2020-01-25-12-58-20 .. nonce: FUZI25 .. section: Library

:mod:pdb now displays exceptions from repr() with its p and pp commands.

.. bpo: 38840 .. date: 2020-01-16-23-41-16 .. nonce: VzzYZz .. section: Library

Fix test___all__ on platforms lacking a shared memory implementation.

.. bpo: 39359 .. date: 2020-01-16-13-54-28 .. nonce: hzTu0h .. section: Library

Add one missing check that the password is a bytes object for an encrypted zipfile.

.. bpo: 38741 .. date: 2019-11-12-18-59-33 .. nonce: W7IYkq .. section: Library

:mod:configparser: using ']' inside a section header will no longer cut the section name short at the ']'

.. bpo: 38415 .. date: 2019-10-08-14-08-59 .. nonce: N1bUw6 .. section: Library

Added missing behavior to :func:contextlib.asynccontextmanager to match :func:contextlib.contextmanager so decorated functions can themselves be decorators.

.. bpo: 30256 .. date: 2019-09-25-13-54-41 .. nonce: wBkzox .. section: Library

Pass multiprocessing BaseProxy argument manager_owned through AutoProxy.

.. bpo: 27513 .. date: 2019-06-03-23-53-25 .. nonce: qITN7d .. section: Library

:func:email.utils.getaddresses now accepts :class:email.header.Header objects along with string values. Patch by Zackery Spytz.

.. bpo: 16379 .. date: 2019-05-08-15-14-32 .. nonce: rN5JVe .. section: Library

Add SQLite error code and name to :mod:sqlite3 exceptions. Patch by Aviv Palivoda, Daniel Shahaf, and Erlend E. Aasland.

.. bpo: 26228 .. date: 2019-02-26-09-31-59 .. nonce: wyrHKc .. section: Library

pty.spawn no longer hangs on FreeBSD, macOS, and Solaris.

.. bpo: 33349 .. date: 2018-04-24-14-25-07 .. nonce: Y_0LIr .. section: Library

lib2to3 now recognizes async generators everywhere.

.. bpo: 29298 .. date: 2017-09-20-14-43-03 .. nonce: _78CSN .. section: Library

Fix TypeError when required subparsers without dest do not receive arguments. Patch by Anthony Sottile.

.. bpo: 45216 .. date: 2021-09-18-13-45-19 .. nonce: o56nyt .. section: Documentation

Remove extra documentation listing methods in difflib. It was rendering twice in pydoc and was outdated in some places.

.. bpo: 45024 .. date: 2021-09-08-17-20-19 .. nonce: dkNPNi .. section: Documentation

:mod:collections.abc documentation has been expanded to explicitly cover how instance and subclass checks work, with additional doctest examples and an exhaustive list of ABCs which test membership purely by presence of the right :term:special method\s. Patch by Raymond Hettinger.

.. bpo: 44957 .. date: 2021-08-19-15-53-08 .. nonce: imqrh3 .. section: Documentation

Promote PEP 604 union syntax by using it where possible. Also, mention X | Y more prominently in section about Union and mention X | None at all in section about Optional.

.. bpo: 16580 .. date: 2021-08-13-20-17-59 .. nonce: MZ_iK9 .. section: Documentation

Added code equivalents for the :meth:int.to_bytes and :meth:int.from_bytes methods, as well as tests ensuring that these code equivalents are valid.

.. bpo: 44903 .. date: 2021-08-13-19-08-03 .. nonce: aJuvQF .. section: Documentation

Removed the othergui.rst file, any references to it, and the list of GUI frameworks in the FAQ. In their place I've added links to the Python Wiki page on GUI frameworks <https://wiki.python.org/moin/GuiProgramming>_.

.. bpo: 33479 .. date: 2021-08-11-18-02-06 .. nonce: rCe4c5 .. section: Documentation

Tkinter documentation has been greatly expanded with new "Architecture" and "Threading model" sections.

.. bpo: 36700 .. date: 2021-08-09-19-58-45 .. nonce: WPNW5f .. section: Documentation

:mod:base64 RFC references were updated to point to :rfc:4648; a section was added to point users to the new "security considerations" section of the RFC.

.. bpo: 44740 .. date: 2021-07-26-23-48-31 .. nonce: zMFGMV .. section: Documentation

Replaced occurrences of uppercase "Web" and "Internet" with lowercase versions per the 2016 revised Associated Press Style Book.

.. bpo: 44693 .. date: 2021-07-25-23-04-15 .. nonce: JuCbNq .. section: Documentation

Update the definition of future in the glossary by replacing the confusing word "pseudo-module" with a more accurate description.

.. bpo: 35183 .. date: 2021-07-22-08-28-03 .. nonce: p9BWTB .. section: Documentation

Add typical examples to os.path.splitext docs

.. bpo: 30511 .. date: 2021-07-20-21-03-18 .. nonce: eMFkRi .. section: Documentation

Clarify that :func:shutil.make_archive is not thread-safe due to reliance on changing the current working directory.

.. bpo: 44561 .. date: 2021-07-18-22-43-14 .. nonce: T7HpWm .. section: Documentation

Update of three expired hyperlinks in Doc/distributing/index.rst: "Project structure", "Building and packaging the project", and "Uploading the project to the Python Packaging Index".

.. bpo: 44651 .. date: 2021-07-18-22-26-02 .. nonce: SjT9iY .. section: Documentation

Delete entry "coercion" in Doc/glossary.rst for its outdated definition.

.. bpo: 42958 .. date: 2021-07-15-11-19-03 .. nonce: gC5IHM .. section: Documentation

Updated the docstring and docs of :func:filecmp.cmp to be more accurate and less confusing especially in respect to shallow arg.

.. bpo: 44631 .. date: 2021-07-13-22-25-13 .. nonce: qkGwe4 .. section: Documentation

Refactored the repr() code of the _Environ (os module).

.. bpo: 44613 .. date: 2021-07-12-11-39-20 .. nonce: DIXNzc .. section: Documentation

importlib.metadata is no longer provisional.

.. bpo: 44558 .. date: 2021-07-03-18-25-17 .. nonce: 0pTknl .. section: Documentation

Match the docstring and python implementation of :func:~operator.countOf to the behavior of its c implementation.

.. bpo: 44544 .. date: 2021-07-02-14-02-29 .. nonce: _5_aCz .. section: Documentation

List all kwargs for :func:textwrap.wrap, :func:textwrap.fill, and :func:textwrap.shorten. Now, there are nav links to attributes of :class:TextWrap, which makes navigation much easier while minimizing duplication in the documentation.

.. bpo: 38062 .. date: 2021-06-28-12-13-48 .. nonce: 9Ehp9O .. section: Documentation

Clarify that atexit uses equality comparisons internally.

.. bpo: 40620 .. date: 2021-06-26-17-41-06 .. nonce: PAYDrB .. section: Documentation

Convert examples in tutorial controlflow.rst section 4.3 to be interpreter-demo style.

.. bpo: 43066 .. date: 2021-06-24-14-37-16 .. nonce: Ti7ahX .. section: Documentation

Added a warning to :mod:zipfile docs: filename arg with a leading slash may cause archive to be un-openable on Windows systems.

.. bpo: 39452 .. date: 2021-06-23-15-21-36 .. nonce: o_I-6d .. section: Documentation

Rewrote Doc/library/__main__.rst. Broadened scope of the document to explicitly discuss and differentiate between __main__.py in packages versus the __name__ == '__main__' expression (and the idioms that surround it).

.. bpo: 13814 .. date: 2021-06-21-15-46-32 .. nonce: LDcslu .. section: Documentation

In the Design FAQ, answer "Why don't generators support the with statement?"

.. bpo: 27752 .. date: 2021-06-18-18-04-53 .. nonce: NEByNk .. section: Documentation

Documentation of csv.Dialect is more descriptive.

.. bpo: 44453 .. date: 2021-06-18-06-44-45 .. nonce: 3PIkj2 .. section: Documentation

Fix documentation for the return type of :func:sysconfig.get_path.

.. bpo: 44392 .. date: 2021-06-16-18-09-49 .. nonce: 6RF1Sc .. section: Documentation

Added a new section in the C API documentation for types used in type hinting. Documented Py_GenericAlias and Py_GenericAliasType.

.. bpo: 38291 .. date: 2021-06-14-09-20-37 .. nonce: VMYa_Q .. section: Documentation

Mark typing.io and typing.re as deprecated since Python 3.8 in the documentation. They were never properly supported by type checkers.

.. bpo: 44322 .. date: 2021-06-06-14-12-00 .. nonce: K0PHfE .. section: Documentation

Document that SyntaxError args have a details tuple and that details are adjusted for errors in f-string field replacement expressions.

.. bpo: 42392 .. date: 2021-05-26-11-16-33 .. nonce: oxRx6E .. section: Documentation

Document the deprecation and removal of the loop parameter for many functions and classes in :mod:asyncio.

.. bpo: 44195 .. date: 2021-05-23-09-11-28 .. nonce: 1bqkOs .. section: Documentation

Corrected references to TraversableResources in docs. There is no TraversableReader.

.. bpo: 41963 .. date: 2021-05-17-20-03-47 .. nonce: eUz9_o .. section: Documentation

Document that ConfigParser strips off comments when reading configuration files.

.. bpo: 44072 .. date: 2021-05-08-09-48-05 .. nonce: fb2x5I .. section: Documentation

Correct where in the numeric ABC hierarchy ** support is added, i.e., in numbers.Complex, not numbers.Integral.

.. bpo: 43558 .. date: 2021-05-07-12-27-09 .. nonce: UGhA8R .. section: Documentation

Add the remark to :mod:dataclasses documentation that the :meth:__init__ of any base class has to be called in :meth:__post_init__, along with a code example.

.. bpo: 44025 .. date: 2021-05-03-22-08-08 .. nonce: gcB7iP .. section: Documentation

Clarify when '_' in match statements is a keyword, and when not.

.. bpo: 41706 .. date: 2020-09-03-13-37-19 .. nonce: _zXWOR .. section: Documentation

Fix docs about how methods like __add__ are invoked when evaluating operator expressions.

.. bpo: 41621 .. date: 2020-08-24-13-35-04 .. nonce: nqaw9G .. section: Documentation

Document that :class:collections.defaultdict parameter default_factory defaults to None and is positional-only.

.. bpo: 41576 .. date: 2020-08-21-22-59-37 .. nonce: 7a6CQR .. section: Documentation

document BaseException in favor of bare except

.. bpo: 21760 .. date: 2020-03-21-01-19-28 .. nonce: CqofIc .. section: Documentation

The description for file fixed. Patch by Furkan Onder

.. bpo: 39498 .. date: 2020-01-30-05-18-48 .. nonce: Nu3sFL .. section: Documentation

Add a "Security Considerations" index which links to standard library modules that have explicitly documented security considerations.

.. bpo: 33479 .. date: 2018-05-19-15-59-29 .. nonce: 4cLlxo .. section: Documentation

Remove the unqualified claim that tkinter is threadsafe. It has not been true for several years and likely never was. An explanation of what is true may be added later, after more discussion, and possibly after patching _tkinter.c,

.. bpo: 40173 .. date: 2021-09-30-16-54-39 .. nonce: J_slCw .. section: Tests

Fix :func:test.support.import_helper.import_fresh_module.

.. bpo: 45280 .. date: 2021-09-25-11-05-31 .. nonce: 3MA6lC .. section: Tests

Add a test case for empty :class:typing.NamedTuple.

.. bpo: 45269 .. date: 2021-09-24-10-41-49 .. nonce: 8jKEr8 .. section: Tests

Cover case when invalid markers type is supplied to c_make_encoder.

.. bpo: 45128 .. date: 2021-09-16-17-22-35 .. nonce: Jz6fl2 .. section: Tests

Fix test_multiprocessing_fork failure due to test_logging and sys.modules manipulation.

.. bpo: 45209 .. date: 2021-09-15-23-32-39 .. nonce: 55ntL5 .. section: Tests

Fix UserWarning: resource_tracker warning in _test_multiprocessing._TestSharedMemory.test_shared_memory_cleaned_after_process_termination

.. bpo: 45185 .. date: 2021-09-14-14-54-04 .. nonce: qFx5I6 .. section: Tests

Enables TestEnumerations test cases in test_ssl suite.

.. bpo: 45195 .. date: 2021-09-14-13-16-18 .. nonce: EyQR1G .. section: Tests

Fix test_readline.test_nonascii(): sometimes, the newline character is not written at the end, so don't expect it in the output. Patch by Victor Stinner.

.. bpo: 45156 .. date: 2021-09-13-00-28-17 .. nonce: 8oomV3 .. section: Tests

Fixes infinite loop on :func:unittest.mock.seal of mocks created by :func:~unittest.create_autospec.

.. bpo: 45125 .. date: 2021-09-11-22-08-18 .. nonce: FVSzs2 .. section: Tests

Improves pickling tests and docs of SharedMemory and SharableList objects.

.. bpo: 44860 .. date: 2021-09-08-13-01-37 .. nonce: qXd0kx .. section: Tests

Update test_sysconfig.test_user_similar() for the posix_user scheme: platlib doesn't use :data:sys.platlibdir. Patch by Victor Stinner.

.. bpo: 45052 .. date: 2021-09-06-19-00-29 .. nonce: yrOK3J .. section: Tests

WithProcessesTestSharedMemory.test_shared_memory_basics test was ignored, because self.assertEqual(sms.size, sms2.size) line was failing. It is now removed and test is unskipped.

The main motivation for this line to be removed from the test is that the size of SharedMemory is not ever guaranteed to be the same. It is decided by the platform.

.. bpo: 44895 .. date: 2021-09-01-17-17-44 .. nonce: kV7H77 .. section: Tests

libregrtest now clears the type cache later to reduce the risk of false alarm when checking for reference leaks. Previously, the type cache was cleared too early and libregrtest raised a false alarm about reference leaks under very specific conditions. Patch by Irit Katriel and Victor Stinner.

.. bpo: 45042 .. date: 2021-08-30-11-54-14 .. nonce: QMz3X8 .. section: Tests

Fixes that test classes decorated with @hashlib_helper.requires_hashdigest were skipped all the time.

.. bpo: 25130 .. date: 2021-08-27-22-37-19 .. nonce: ig4oJe .. section: Tests

Add calls of :func:gc.collect in tests to support PyPy.

.. bpo: 45011 .. date: 2021-08-26-14-20-44 .. nonce: mQZdXU .. section: Tests

Made tests relying on the :mod:!_asyncio C extension module optional to allow running on alternative Python implementations. Patch by Serhiy Storchaka.

.. bpo: 44949 .. date: 2021-08-18-18-30-12 .. nonce: VE5ENv .. section: Tests

Fix auto history tests of test_readline: sometimes, the newline character is not written at the end, so don't expect it in the output.

.. bpo: 44891 .. date: 2021-08-13-12-11-06 .. nonce: T9_mBT .. section: Tests

Tests were added to clarify :func:id is preserved when obj * 1 is used on :class:str and :class:bytes objects. Patch by Nikita Sobolev.

.. bpo: 44852 .. date: 2021-08-06-18-36-04 .. nonce: sUL8YX .. section: Tests

Add ability to wholesale silence DeprecationWarnings while running the regression test suite.

.. bpo: 40928 .. date: 2021-08-06-00-07-15 .. nonce: aIwb6G .. section: Tests

Notify users running test_decimal regression tests on macOS of potential harmless "malloc can't allocate region" messages spewed by test_decimal.

.. bpo: 44734 .. date: 2021-07-24-20-09-15 .. nonce: KKsNOV .. section: Tests

Fixed floating-point precision issue in turtle tests.

.. bpo: 44708 .. date: 2021-07-22-16-38-39 .. nonce: SYNaac .. section: Tests

Regression tests, when run with -w, are now re-running only the affected test methods instead of re-running the entire test file.

.. bpo: 42095 .. date: 2021-07-17-11-41-20 .. nonce: kCB7oj .. section: Tests

Added interop tests for Apple plists: generate plist files with Python plistlib and parse with Apple plutil; and the other way round.

.. bpo: 44647 .. date: 2021-07-16-14-02-33 .. nonce: 5LzqIy .. section: Tests

Added a permanent Unicode-valued environment variable to regression tests to ensure they handle this use case in the future. If your test environment breaks because of that, report a bug to us, and temporarily set PYTHONREGRTEST_UNICODE_GUARD=0 in your test environment.

.. bpo: 44515 .. date: 2021-06-26-18-37-36 .. nonce: e9fO6f .. section: Tests

Adjust recently added contextlib tests to avoid assuming the use of a refcounted GC

.. bpo: 44287 .. date: 2021-06-21-17-53-41 .. nonce: YON57s .. section: Tests

Fix asyncio test_popen() of test_windows_utils by using a longer timeout. Use military grade battle-tested :data:test.support.SHORT_TIMEOUT timeout rather than a hardcoded timeout of 10 seconds: it's 30 seconds by default, but it is made longer on slow buildbots. Patch by Victor Stinner.

.. bpo: 44451 .. date: 2021-06-18-15-19-35 .. nonce: aj5pqE .. section: Tests

Reset DeprecationWarning filters in test.test_importlib.test_metadata_api.APITests.test_entry_points_by_index to avoid StopIteration error if DeprecationWarnings are ignored.

.. bpo: 44363 .. date: 2021-06-10-11-19-43 .. nonce: -K9jD0 .. section: Tests

Account for address sanitizer in test_capi. test_capi now passes when run GCC address sanitizer.

.. bpo: 44364 .. date: 2021-06-09-15-32-05 .. nonce: zu9Zee .. section: Tests

Add non integral tests for :func:math.sqrt function.

.. bpo: 43921 .. date: 2021-06-03-03-29-34 .. nonce: nwH1FS .. section: Tests

Fix test_ssl.test_wrong_cert_tls13(): use suppress_ragged_eofs=False, since read() can raise :exc:ssl.SSLEOFError on Windows. Patch by Victor Stinner.

.. bpo: 43921 .. date: 2021-06-02-17-41-42 .. nonce: xP7yZ4 .. section: Tests

Fix test_pha_required_nocert() of test_ssl: catch two more EOF cases (when the recv() method returns an empty string). Patch by Victor Stinner.

.. bpo: 44131 .. date: 2021-05-14-14-13-44 .. nonce: YPizoC .. section: Tests

Add test_frozenmain to test_embed to test the :c:func:Py_FrozenMain C function. Patch by Victor Stinner.

.. bpo: 31904 .. date: 2021-05-07-15-46-04 .. nonce: 8dk3la .. section: Tests

Ignore error string case in test_file_not_exists().

.. bpo: 42083 .. date: 2021-05-04-18-10-57 .. nonce: EMS2TK .. section: Tests

Add test to check that PyStructSequence_NewType accepts a PyStructSequence_Desc with doc field set to NULL.

.. bpo: 35753 .. date: 2020-10-25-19-20-26 .. nonce: 2LT-hO .. section: Tests

Fix crash in doctest when doctest parses modules that include unwrappable functions by skipping those functions.

.. bpo: 30256 .. date: 2019-09-25-18-10-10 .. nonce: A5i76Q .. section: Tests

Add test for nested queues when using multiprocessing shared objects AutoProxy[Queue] inside ListProxy and DictProxy

.. bpo: 45220 .. date: 2021-09-16-18-00-43 .. nonce: TgbkvW .. section: Build

Avoid building with the Windows 11 SDK previews automatically. This may be overridden by setting the DefaultWindowsSDKVersion environment variable before building.

.. bpo: 45020 .. date: 2021-09-14-10-07-23 .. nonce: _VGGPv .. section: Build

Freeze stdlib modules that are imported during startup. This provides significant performance improvements to startup. If necessary, use the previously added "-X frozen_modules=off" commandline option to force importing the source modules.

.. bpo: 45188 .. date: 2021-09-14-00-47-57 .. nonce: MNbo_T .. section: Build

Windows builds now regenerate frozen modules as the first part of the build. Previously the regeneration was later in the build, which would require it to be restarted if any modules had changed.

.. bpo: 45163 .. date: 2021-09-11-06-05-23 .. nonce: q7xT93 .. section: Build

Fixes Haiku platform build.

.. bpo: 45067 .. date: 2021-09-09-16-45-26 .. nonce: mFmY92 .. section: Build

The ncurses function extended_color_content was introduced in 2017

(https://invisible-island.net/ncurses/NEWS.html#index-t20170401). The

ncurses-devel package in CentOS 7 had a older version ncurses resulted in compilation error. For compiling ncurses with extended color support, we verify the version of the ncurses library >= 20170401.

.. bpo: 45019 .. date: 2021-08-26-13-10-46 .. nonce: e0mo49 .. section: Build

Generate lines in relevant files for frozen modules. Up until now each of the files had to be edited manually. This change makes it easier to add to and modify the frozen modules.

.. bpo: 44340 .. date: 2021-07-19-01-09-56 .. nonce: JNeOf4 .. section: Build

Add support for building with clang thin lto via --with-lto=thin/full. Patch by Donghee Na and Brett Holman.

.. bpo: 44535 .. date: 2021-06-30-02-32-46 .. nonce: M9iN4- .. section: Build

Enable building using a Visual Studio 2022 install on Windows.

.. bpo: 43298 .. date: 2021-06-19-11-50-03 .. nonce: 9ircMb .. section: Build

Improved error message when building without a Windows SDK installed.

.. bpo: 44381 .. date: 2021-06-10-18-08-44 .. nonce: Xpc1iX .. section: Build

The Windows build now accepts :envvar:EnableControlFlowGuard set to guard to enable CFG.

.. bpo: 41282 .. date: 2021-05-24-03-31-17 .. nonce: L8nP44 .. section: Build

Fix broken make install that caused standard library extension modules to be unnecessarily and incorrectly rebuilt during the install phase of cpython.

.. bpo: 45375 .. date: 2021-10-05-12-41-53 .. nonce: CohPP- .. section: Windows

Fixes an assertion failure due to searching for the standard library in unnormalised paths.

.. bpo: 45022 .. date: 2021-09-03-18-05-21 .. nonce: bgpD_r .. section: Windows

Update Windows release to include libffi 3.4.2

.. bpo: 45007 .. date: 2021-08-27-23-50-02 .. nonce: NIBlVG .. section: Windows

Update to OpenSSL 1.1.1l in Windows build

.. bpo: 44848 .. date: 2021-08-06-10-11-07 .. nonce: ib3Jcz .. section: Windows

Upgrade Windows installer to use SQLite 3.36.0.

.. bpo: 44572 .. date: 2021-07-13-15-32-49 .. nonce: gXvhDc .. section: Windows

Avoid consuming standard input in the :mod:platform module

.. bpo: 44582 .. date: 2021-07-07-21-07-18 .. nonce: 4Mm6Hh .. section: Windows

Accelerate speed of :mod:mimetypes initialization using a native implementation of the registry scan.

.. bpo: 41299 .. date: 2021-06-06-16-36-13 .. nonce: Rg-vb_ .. section: Windows

Fix 16 milliseconds jitter when using timeouts in :mod:threading, such as with :meth:threading.Lock.acquire or :meth:threading.Condition.wait.

.. bpo: 42686 .. date: 2021-01-01-21-21-03 .. nonce: G_f-TC .. section: Windows

Build :mod:sqlite3 with math functions enabled. Patch by Erlend E. Aasland.

.. bpo: 40263 .. date: 2020-04-13-15-20-28 .. nonce: 1KKEbu .. section: Windows

This is a follow-on bug from https://bugs.python.org/issue26903. Once that is applied we run into an off-by-one assertion problem. The assert was not correct.

.. bpo: 45007 .. date: 2021-08-30-00-04-10 .. nonce: pixqUB .. section: macOS

Update macOS installer builds to use OpenSSL 1.1.1l.

.. bpo: 34602 .. date: 2021-08-27-16-55-10 .. nonce: ZjHsYJ .. section: macOS

When building CPython on macOS with ./configure --with-undefined-behavior-sanitizer --with-pydebug, the stack size is now quadrupled to allow for the entire test suite to pass.

.. bpo: 44848 .. date: 2021-08-06-10-08-41 .. nonce: 0uYXsE .. section: macOS

Update macOS installer to use SQLite 3.36.0.

.. bpo: 44689 .. date: 2021-07-20-22-27-01 .. nonce: mmT_xH .. section: macOS

:meth:ctypes.util.find_library now works correctly on macOS 11 Big Sur even if Python is built on an older version of macOS. Previously, when built on older macOS systems, find_library was not able to find macOS system libraries when running on Big Sur due to changes in how system libraries are stored.

.. bpo: 41972 .. date: 2021-07-12-15-42-02 .. nonce: yUjE8j .. section: macOS

The framework build's user header path in sysconfig is changed to add a 'pythonX.Y' component to match distutils's behavior.

.. bpo: 43109 .. date: 2021-05-24-21-15-41 .. nonce: npKJ9c .. section: macOS

Allow --with-lto configure option to work with Apple-supplied Xcode or Command Line Tools.

.. bpo: 34932 .. date: 2021-03-29-21-11-23 .. nonce: f3Hdyd .. section: macOS

Add socket.TCP_KEEPALIVE support for macOS. Patch by Shane Harvey.

.. bpo: 45296 .. date: 2021-09-27-01-21-59 .. nonce: 9H8rdY .. section: IDLE

On Windows, change exit/quit message to suggest Ctrl-D, which works, instead of <Ctrl-Z Return>, which does not work in IDLE.

.. bpo: 45193 .. date: 2021-09-15-03-20-06 .. nonce: G61_GV .. section: IDLE

Make completion boxes appear on Ubuntu again.

.. bpo: 40128 .. date: 2021-06-11-17-43-39 .. nonce: 7vDN3U .. section: IDLE

Mostly fix completions on macOS when not using tcl/tk 8.6.11 (as with 3.9). The added update_idletask call should be harmless and possibly helpful otherwise.

.. bpo: 33962 .. date: 2021-06-10-00-50-02 .. nonce: ikAUNg .. section: IDLE

Move the indent space setting from the Font tab to the new Windows tab. Patch by Mark Roseman and Terry Jan Reedy.

.. bpo: 40468 .. date: 2021-06-08-03-04-51 .. nonce: tUCGUb .. section: IDLE

Split the settings dialog General tab into Windows and Shell/ED tabs. Move help sources, which extend the Help menu, to the Extensions tab. Make space for new options and shorten the dialog. The latter makes the dialog better fit small screens.

.. bpo: 41611 .. date: 2021-05-27-18-22-46 .. nonce: jOKpfc .. section: IDLE

Avoid uncaught exceptions in AutoCompleteWindow.winconfig_event().

.. bpo: 41611 .. date: 2021-05-27-13-39-43 .. nonce: liNQqj .. section: IDLE

Fix IDLE sometimes freezing upon tab-completion on macOS.

.. bpo: 44010 .. date: 2021-05-09-09-02-09 .. nonce: TaLe9x .. section: IDLE

Highlight the new :ref:match <match> statement's :ref:soft keywords <soft-keywords>: :keyword:match, :keyword:case <match>, and :keyword:_ <wildcard-patterns>. However, this highlighting is not perfect and will be incorrect in some rare cases, including some _-s in case patterns.

.. bpo: 44026 .. date: 2021-05-05-09-45-24 .. nonce: m2Z0zR .. section: IDLE

Include interpreter's typo fix suggestions in message line for NameErrors and AttributeErrors. Patch by E. Paine.

.. bpo: 44786 .. date: 2021-09-14-11-44-26 .. nonce: DU0LC0 .. section: Tools/Demos

Fix a warning in regular expression in the c-analyzer script.

.. bpo: 44967 .. date: 2021-08-26-11-57-31 .. nonce: UT1RMV .. section: Tools/Demos

pydoc now returns a non-zero status code when a module cannot be found.

.. bpo: 44978 .. date: 2021-08-22-11-45-31 .. nonce: QupKV3 .. section: Tools/Demos

Allow the Argument Clinic tool to handle __complex__ special methods.

.. bpo: 43425 .. date: 2021-07-01-22-21-25 .. nonce: t65len .. section: Tools/Demos

Removed the 'test2to3' demo project that demonstrated using lib2to3 to support Python 2.x and Python 3.x from a single source in a distutils package. Patch by Donghee Na

.. bpo: 44074 .. date: 2021-05-08-13-57-00 .. nonce: F09kCK .. section: Tools/Demos

Make patchcheck automatically detect the correct base branch name (previously it was hardcoded to 'master')

.. bpo: 20291 .. date: 2020-02-25-18-22-09 .. nonce: AyrDiZ .. section: Tools/Demos

Added support for variadic positional parameters in Argument Clinic.

.. bpo: 41710 .. date: 2021-09-30-03-14-35 .. nonce: DDWJKx .. section: C API

The PyThread_acquire_lock_timed() function now clamps the timeout if it is too large, rather than aborting the process. Patch by Victor Stinner.

.. bpo: 44687 .. date: 2021-09-19-17-18-25 .. nonce: 3fqDRC .. section: C API

:meth:BufferedReader.peek no longer raises :exc:ValueError when the entire file has already been buffered.

.. bpo: 45116 .. date: 2021-09-16-18-05-20 .. nonce: WxXewl .. section: C API

Add the :c:macro:Py_ALWAYS_INLINE macro to ask the compiler to always inline a static inline function. The compiler can ignore it and decides to not inline the function. Patch by Victor Stinner.

.. bpo: 45094 .. date: 2021-09-03-15-53-43 .. nonce: tinXwL .. section: C API

Add the :c:macro:Py_NO_INLINE macro to disable inlining on a function. Patch by Victor Stinner.

.. bpo: 45061 .. date: 2021-08-31-15-21-36 .. nonce: ZH0HVe .. section: C API

Add a deallocator to the :class:bool type to detect refcount bugs in C extensions which call Py_DECREF(Py_True); or Py_DECREF(Py_False); by mistake. Patch by Victor Stinner.

.. bpo: 42035 .. date: 2021-08-02-20-49-36 .. nonce: HTBcZt .. section: C API

Add a new :c:func:PyType_GetQualName function to get type's qualified name.

.. bpo: 41103 .. date: 2021-07-29-16-04-28 .. nonce: hiKKcF .. section: C API

Reverts removal of the old buffer protocol because they are part of stable ABI.

.. bpo: 44751 .. date: 2021-07-27-17-29-12 .. nonce: 4qmbDG .. section: C API

Remove crypt.h include from the public Python.h header.

.. bpo: 42747 .. date: 2021-07-20-16-21-06 .. nonce: rRxjUY .. section: C API

The Py_TPFLAGS_HAVE_VERSION_TAG type flag now does nothing. The Py_TPFLAGS_HAVE_AM_SEND flag (which was added in 3.10) is removed. Both were unnecessary because it is not possible to have type objects with the relevant fields missing.

.. bpo: 44530 .. date: 2021-06-28-23-44-47 .. nonce: qij7YC .. section: C API

Added the co_qualname to the PyCodeObject structure to propagate the qualified name from the compiler to code objects.

Patch by Gabriele N. Tornetta

.. bpo: 44441 .. date: 2021-06-23-12-12-04 .. nonce: 3p14JB .. section: C API

:c:func:Py_RunMain now resets :c:data:PyImport_Inittab to its initial value at exit. It must be possible to call :c:func:PyImport_AppendInittab or :c:func:PyImport_ExtendInittab at each Python initialization. Patch by Victor Stinner.

.. bpo: 39947 .. date: 2021-06-23-10-31-45 .. nonce: je_HMo .. section: C API

Remove 4 private trashcan C API functions which were only kept for the backward compatibility of the stable ABI with Python 3.8 and older, since the trashcan API was not usable with the limited C API on Python 3.8 and older. The trashcan API was excluded from the limited C API in Python 3.9.

Removed functions:

_PyTrash_deposit_object()
_PyTrash_destroy_chain()
_PyTrash_thread_deposit_object()
_PyTrash_thread_destroy_chain()

The trashcan C API was never usable with the limited C API, since old trashcan macros accessed directly :c:type:PyThreadState members like _tstate->trash_delete_nesting, whereas the :c:type:PyThreadState structure is opaque in the limited C API.

Exclude also the PyTrash_UNWIND_LEVEL constant from the C API.

Patch by Victor Stinner.

.. bpo: 40939 .. date: 2021-06-22-17-00-06 .. nonce: CGB0I5 .. section: C API

Removed documentation for the removed PyParser_* C API.

.. bpo: 43795 .. date: 2021-06-15-16-28-18 .. nonce: fy0AXK .. section: C API

The list in :ref:limited-api-list now shows the public name :c:struct:PyFrameObject rather than _frame. The non-existing entry _node no longer appears in the list.

.. bpo: 44378 .. date: 2021-06-10-15-22-31 .. nonce: jGYakF .. section: C API

:c:func:Py_IS_TYPE no longer uses :c:func:Py_TYPE to avoid a compiler warning: no longer cast const PyObject* to PyObject*. Patch by Victor Stinner.

.. bpo: 39573 .. date: 2021-06-03-00-59-48 .. nonce: -elHTJ .. section: C API

Convert the :c:func:Py_TYPE and :c:func:Py_SIZE macros to static inline functions. The :c:func:Py_SET_TYPE and :c:func:Py_SET_SIZE functions must now be used to set an object type and size. Patch by Victor Stinner.

.. bpo: 44263 .. date: 2021-05-31-11-31-13 .. nonce: 8mIOfV .. section: C API

The :c:func:PyType_Ready function now raises an error if a type is defined with the :c:macro:Py_TPFLAGS_HAVE_GC flag set but has no traverse function (:c:member:PyTypeObject.tp_traverse). Patch by Victor Stinner.

.. bpo: 43795 .. date: 2021-05-19-15-09-47 .. nonce: WAHRxt .. section: C API

The undocumented function :c:func:Py_FrozenMain is removed from the Limited API.

.. bpo: 44113 .. date: 2021-05-12-12-24-45 .. nonce: DcgOqE .. section: C API

Deprecate the following functions to configure the Python initialization:

:c:func:!PySys_AddWarnOptionUnicode
:c:func:!PySys_AddWarnOption
:c:func:!PySys_AddXOption
:c:func:!PySys_HasWarnOptions
:c:func:!Py_SetPath
:c:func:!Py_SetProgramName
:c:func:!Py_SetPythonHome
:c:func:!Py_SetStandardStreamEncoding
:c:func:!_Py_SetProgramFullPath

Use the new :c:type:PyConfig API of the :ref:Python Initialization Configuration <init-config> instead (:pep:587).

.. bpo: 44094 .. date: 2021-05-10-14-34-22 .. nonce: HayXZO .. section: C API

Remove PyErr_SetFromErrnoWithUnicodeFilename(), PyErr_SetFromWindowsErrWithUnicodeFilename(), and PyErr_SetExcFromWindowsErrWithUnicodeFilename(). They are not documented and have been deprecated since Python 3.3.

.. bpo: 43795 .. date: 2021-05-05-19-04-50 .. nonce: 9Ojj73 .. section: C API

:c:func:PyCodec_Unregister is now properly exported as a function in the Windows Stable ABI DLL.

.. bpo: 44029 .. date: 2021-05-04-17-43-39 .. nonce: ayX4PR .. section: C API

Remove deprecated Py_UNICODE APIs: PyUnicode_Encode, PyUnicode_EncodeUTF7, PyUnicode_EncodeUTF8, PyUnicode_EncodeUTF16, PyUnicode_EncodeUTF32, PyUnicode_EncodeLatin1, PyUnicode_EncodeMBCS, PyUnicode_EncodeDecimal, PyUnicode_EncodeRawUnicodeEscape, PyUnicode_EncodeCharmap, PyUnicode_EncodeUnicodeEscape, PyUnicode_TransformDecimalToASCII, PyUnicode_TranslateCharmap, PyUnicodeEncodeError_Create, PyUnicodeTranslateError_Create. See :pep:393 and :pep:624 for reference.

.. bpo: 42035 .. date: 2020-12-23-01-28-50 .. nonce: S9eUm0 .. section: C API

Add a new :c:func:PyType_GetName function to get type's short name.