Changelog

Python next

Release date: XXXX-XX-XX

Security

  • gh-108310: Fixed an issue where instances of ssl.SSLSocket were vulnerable to a bypass of the TLS handshake and included protections (like certificate verification) and treating sent unencrypted data as if it were post-handshake TLS encrypted data. Security issue reported as CVE-2023-40217 by Aapo Oksman. Patch by Gregory P. Smith.

  • gh-107774: PEP 669 specifies that sys.monitoring.register_callback will generate an audit event. Pre-releases of Python 3.12 did not generate the audit event. This is now fixed.

  • gh-102988: Reverted the email.utils security improvement change released in 3.12beta4 that unintentionally caused email.utils.getaddresses to fail to parse email addresses with a comma in the quoted name field. See gh-106669.

  • gh-99108: Refresh our new HACL* built-in hashlib code from upstream. Built-in SHA2 should be faster and an issue with SHA3 on 32-bit platforms is fixed.

  • gh-102509: Start initializing ob_digit during creation of PyLongObject objects. Patch by Illia Volochii.

Core and Builtins

  • gh-109889: Fix the compiler’s redundant NOP detection algorithm to skip over NOPs with no line number when looking for the next instruction’s lineno.

  • gh-109923: Set line number on the POP_TOP that follows a RETURN_GENERATOR.

  • gh-109823: Fix bug where compiler does not adjust labels when removing an empty basic block which is a jump target.

  • gh-109793: The main thread no longer exits prematurely when a subinterpreter is cleaned up during runtime finalization. The bug was a problem particularly because, when triggered, the Python process would always return with a 0 exitcode, even if it failed.

  • gh-109719: Fix missing jump target labels when compiler reorders cold/warm blocks.

  • gh-109627: Fix bug where the compiler does not assign a new jump target label to a duplicated small exit block.

  • gh-109596: Fix some tokens in the grammar that were incorrectly marked as soft keywords. Also fix some repeated rule names and ensure that repeated rules are not allowed. Patch by Pablo Galindo

  • gh-109496: On a Python built in debug mode, Py_DECREF() now calls _Py_NegativeRefcount() if the object is a dangling pointer to deallocated memory: memory filled with 0xDD “dead byte” by the debug hook on memory allocators. The fix is to check the reference count before checking for _Py_IsImmortal(). Patch by Victor Stinner.

  • gh-107265: Deopt opcodes hidden by the executor when base opcode is needed

  • gh-109371: Deopted instructions correctly for tool initialization and modified the incorrect assertion in instrumentation, when a previous tool already sets INSTRUCTION events

  • gh-105658: Fix bug where the line trace of an except block ending with a conditional includes an excess event with the line of the conditional expression.

  • gh-109219: Fix compiling type param scopes that use a name which is also free in an inner scope.

  • gh-109351: Fix crash when compiling an invalid AST involving a named (walrus) expression.

  • gh-109341: Fix crash when compiling an invalid AST involving a ast.TypeAlias.

  • gh-109195: Fix source location for the LOAD_* instruction preceding a LOAD_SUPER_ATTR to load the super global (or shadowing variable) so that it encompasses only the name super and not the following parentheses.

  • gh-109256: Opcode IDs for specialized opcodes are allocated in their own range to improve stability of the IDs for the ‘real’ opcodes.

  • gh-109216: Fix possible memory leak in BUILD_MAP.

  • gh-109207: Fix a SystemError in __repr__ of symtable entry object.

  • gh-109179: Fix bug where the C traceback display drops notes from SyntaxError.

  • gh-109118: Disallow nested scopes (lambdas, generator expressions, and comprehensions) within PEP 695 annotation scopes that are nested within classes.

  • gh-109156: Add tests for de-instrumenting instructions while keeping the instrumentation for lines

  • gh-109114: Relax the detection of the error message for invalid lambdas inside f-strings to not search for arbitrary replacement fields to avoid false positives. Patch by Pablo Galindo

  • gh-105848: Add a new CALL_KW opcode, used for calls containing keyword arguments. Also, fix a possible crash when jumping over method calls in a debugger.

  • gh-109052: Use the base opcode when comparing code objects to avoid interference from instrumentation

  • gh-109118: Fix interpreter crash when a NameError is raised inside the type parameters of a generic class.

  • gh-88943: Improve syntax error for non-ASCII character that follows a numerical literal. It now points on the invalid non-ASCII character, not on the valid numerical literal.

  • gh-108976: Fix crash that occurs after de-instrumenting a code object in a monitoring callback.

  • gh-108732: Make iteration variables of module- and class-scoped comprehensions visible to pdb and other tools that use frame.f_locals again.

  • gh-108959: Fix caret placement for error locations for subscript and binary operations that involve non-semantic parentheses and spaces. Patch by Pablo Galindo

  • gh-104584: Fix a crash when running with PYTHONUOPS or -X uops enabled and an error occurs during optimization.

  • gh-108727: Define tp_dealloc for CounterOptimizer_Type. This fixes a segfault on deallocation.

  • gh-108520: Fix multiprocessing.synchronize.SemLock.__setstate__() to properly initialize multiprocessing.synchronize.SemLock._is_fork_ctx. This fixes a regression when passing a SemLock accross nested processes.

    Rename multiprocessing.synchronize.SemLock.is_fork_ctx to multiprocessing.synchronize.SemLock._is_fork_ctx to avoid exposing it as public API.

  • gh-108654: Restore locals shadowed by an inlined comprehension if the comprehension raises an exception.

  • gh-108488: Change the initialization of inline cache entries so that the cache entry for JUMP_BACKWARD is initialized to zero, instead of the adaptive_counter_warmup() value used for all other instructions. This counter, unique among instructions, counts up from zero.

  • gh-108716: Turn off deep-freezing of code objects. Modules are still frozen, so that a file system search is not needed for common modules.

  • gh-108614: Add RESUME_CHECK instruction, to avoid having to handle instrumentation, signals, and contexts switches in the tier 2 execution engine.

  • gh-108487: Move an assert that would cause a spurious crash in a devious case that should only trigger deoptimization.

  • gh-106176: Use a WeakValueDictionary to track the lists containing the modules each thread is currently importing. This helps avoid a reference leak from keeping the list around longer than necessary. Weakrefs are used as GC can’t interrupt the cleanup.

  • gh-105481: The regen-opcode build stage was removed and its work is now done in regen-cases.

  • gh-107901: Fix missing line number on JUMP_BACKWARD at the end of a for loop.

  • gh-108113: The compile() built-in can now accept a new flag, ast.PyCF_OPTIMIZED_AST, which is similar to ast.PyCF_ONLY_AST except that the returned AST is optimized according to the value of the optimize argument.

    ast.parse() now accepts an optional argument optimize which is passed on to the compile() built-in. This makes it possible to obtain an optimized AST.

  • gh-107971: Opcode IDs are generated from bytecodes.c instead of being hard coded in opcode.py.

  • gh-107944: Improve error message for function calls with bad keyword arguments. Patch by Pablo Galindo

  • gh-108390: Raise an exception when setting a non-local event (RAISE, EXCEPTION_HANDLED, etc.) in sys.monitoring.set_local_events.

    Fixes crash when tracing in recursive calls to Python classes.

  • gh-108035: Remove the _PyCFrame struct, moving the pointer to the current intepreter frame back to the threadstate, as it was for 3.10 and earlier. The _PyCFrame existed as a performance optimization for tracing. Since PEP 669 has been implemented, this optimization no longer applies.

  • gh-91051: Fix abort / segfault when using all eight type watcher slots, on platforms where char is signed by default.

  • gh-106581: Fix possible assertion failures and missing instrumentation events when PYTHONUOPS or -X uops is enabled.

  • gh-107526: Revert converting vars, dir, next, getattr, and iter to argument clinic.

  • gh-84805: Autogenerate signature for METH_NOARGS and METH_O extension functions.

  • gh-107758: Make the dump_stack() routine used by the lltrace feature (low-level interpreter debugging) robust against recursion by ensuring that it never calls a __repr__ method implemented in Python. Also make the similar output for Tier-2 uops appear on stdout (instead of stderr), to match the lltrace code in ceval.c.

  • gh-107659: Add docstrings for ctypes.pointer() and ctypes.POINTER().

  • gh-105848: Modify the bytecode so that the actual callable for a CALL is at a consistent position on the stack (regardless of whether or not bound-method-calling optimizations are active).

  • gh-107674: Fixed performance regression in sys.settrace.

  • gh-107724: In pre-release versions of 3.12, up to rc1, the sys.monitoring callback function for the PY_THROW event was missing the third, exception argument. That is now fixed.

  • gh-84436: Skip reference count modifications for many known immortal objects.

  • gh-107596: Specialize subscripting str objects by int indexes.

  • gh-107080: Trace refs builds (--with-trace-refs) were crashing when used with isolated subinterpreters. The problematic global state has been isolated to each interpreter. Other fixing the crashes, this change does not affect users.

  • gh-107557: Generate the cases needed for the barebones tier 2 abstract interpreter for optimization passes in CPython.

  • gh-106608: Make _PyUOpExecutorObject variable length.

  • gh-100964: Clear generators’ exception state after return to break reference cycles.

  • gh-107455: Improve error messages when converting an incompatible type to ctypes.c_char_p, ctypes.c_wchar_p and ctypes.c_void_p.

  • gh-107263: Increase C recursion limit for functions other than the main interpreter from 800 to 1500. This should allow functions like list.__repr__ and json.dumps to handle all the inputs that they could prior to 3.12

  • gh-104584: Fix an issue which caused incorrect inline caches to be read when running with PYTHONUOPS or -X uops enabled.

  • gh-104432: Fix potential unaligned memory access on C APIs involving returned sequences of char * pointers within the grp and socket modules. These were revealed using a -fsaniziter=alignment build on ARM macOS. Patch by Christopher Chavez.

  • gh-106078: Isolate _decimal (apply PEP 687). Patch by Charlie Zhao.

  • gh-106898: Add the exception as the third argument to PY_UNIND callbacks in sys.monitoring. This makes the PY_UNWIND callback consistent with the other exception hanlding callbacks.

  • gh-106895: Raise a ValueError when a monitoring callback funtion returns DISABLE for events that cannot be disabled locally.

  • gh-106897: Add a RERAISE event to sys.monitoring, which occurs when an exception is reraise, either explicitly by a plain raise statement, or implicitly in an except or finally block.

  • gh-77377: Ensure that multiprocessing synchronization objects created in a fork context are not sent to a different process created in a spawn context. This changes a segfault into an actionable RuntimeError in the parent process.

  • gh-106931: Statically allocated string objects are now interned globally instead of per-interpreter. This fixes a situation where such a string would only be interned in a single interpreter. Normal string objects are unaffected.

  • gh-104621: Unsupported modules now always fail to be imported.

  • gh-107122: Add dbm.ndbm.ndbm.clear() to dbm.ndbm. Patch By Donghee Na.

  • gh-107122: Add dbm.gnu.gdbm.clear() to dbm.gnu. Patch By Donghee Na.

  • gh-107015: The ASYNC and AWAIT tokens are removed from the Grammar, which removes the posibility of making async and await soft keywords when using feature_version<7 in ast.parse().

  • gh-106917: Fix classmethod-style super() method calls (i.e., where the second argument to super(), or the implied second argument drawn from self/cls in the case of zero-arg super, is a type) when the target of the call is not a classmethod.

  • gh-105699: Python no longer crashes due an infrequent race when initialzing per-interpreter interned strings. The crash would manifest when the interpreter was finalized.

  • gh-105699: Python no longer crashes due to an infrequent race in setting Py_FileSystemDefaultEncoding and Py_FileSystemDefaultEncodeErrors (both deprecated), when simultaneously initializing two isolated subinterpreters. Now they are only set during runtime initialization.

  • gh-106908: Fix various hangs, reference leaks, test failures, and tracing/introspection bugs when running with PYTHONUOPS or -X uops enabled.

  • gh-106092: Fix a segmentation fault caused by a use-after-free bug in frame_dealloc when the trashcan delays the deallocation of a PyFrameObject.

  • gh-106485: Reduce the number of materialized instances dictionaries by dematerializing them when possible.

  • gh-106719: No longer suppress arbitrary errors in the __annotations__ getter and setter in the type and module types.

  • gh-106723: Propagate frozen_modules to multiprocessing spawned process interpreters.

  • gh-104909: Split LOAD_ATTR_INSTANCE_VALUE into micro-ops.

  • gh-104909: Split LOAD_GLOBAL specializations into micro-ops.

  • gh-106597: A new debug structure of offsets has been added to the _PyRuntimeState that will help out-of-process debuggers and profilers to obtain the offsets to relevant interpreter structures in a way that is agnostic of how Python was compiled and that doesn’t require copying the headers. Patch by Pablo Galindo

  • gh-106487: Allow the count argument of str.replace() to be a keyword. Patch by Hugo van Kemenade.

  • gh-96844: Improve error message of list.remove(). Patch by Donghee Na.

  • gh-81283: Compiler now strips indents from docstrings. It reduces pyc file size 5% when the module is heavily documented. This change affects to __doc__ so tools like doctest will be affected.

  • gh-106396: When the format specification of an f-string expression is empty, the parser now generates an empty ast.JoinedStr node for it instead of an one-element ast.JoinedStr with an empty string ast.Constant.

  • gh-100288: Specialize LOAD_ATTR for non-descriptors on the class. Adds LOAD_ATTR_NONDESCRIPTOR_WITH_VALUES and LOAD_ATTR_NONDESCRIPTOR_NO_DICT.

  • gh-106008: Fix possible reference leaks when failing to optimize comparisons with None in the bytecode compiler.

  • gh-106145: Make end_lineno and end_col_offset required on type_param ast nodes.

  • gh-106213: Changed the way that Emscripten call trampolines work for compatibility with Wasm/JS Promise integration.

  • gh-106182: sys.getfilesystemencoding() and sys.getfilesystemencodeerrors now return interned Unicode object.

  • gh-106210: Removed Emscripten import trampoline as it was no longer necessary for Pyodide.

  • gh-104584: Added a new, experimental, tracing optimizer and interpreter (a.k.a. “tier 2”). This currently pessimizes, so don’t use yet – this is infrastructure so we can experiment with optimizing passes. To enable it, pass -Xuops or set PYTHONUOPS=1. To get debug output, set PYTHONUOPSDEBUG=N where N is a debug level (0-4, where 0 is no debug output and 4 is excessively verbose).

  • gh-105775: LOAD_CLOSURE is now a pseudo-op.

  • gh-105730: Allow any callable other than type objects as the condition predicate in BaseExceptionGroup.split() and BaseExceptionGroup.subgroup().

  • gh-105979: Fix crash in _imp.get_frozen_object() due to improper exception handling.

  • gh-106003: Add a new TO_BOOL instruction, which performs boolean conversions for POP_JUMP_IF_TRUE, POP_JUMP_IF_FALSE, and UNARY_NOT (which all expect exact bool values now). Also, modify the oparg of COMPARE_OP to include an optional “boolean conversion” flag.

  • gh-98931: Ensure custom SyntaxError error messages are raised for invalid imports with multiple targets. Patch by Pablo Galindo

  • gh-105724: Improve assert error messages by providing exact error range.

  • gh-105908: Fixed bug where gh-99111 breaks future import barry_as_FLUFL in the Python REPL.

  • gh-105840: Fix possible crashes when specializing function calls with too many __defaults__.

  • gh-105831: Fix an f-string bug, where using a debug expression (the = sign) that appears in the last line of a file results to the debug buffer that holds the expression text being one character too small.

  • gh-105800: Correctly issue SyntaxWarning in f-strings if invalid sequences are used. Patch by Pablo Galindo

  • gh-105340: Include the comprehension iteration variable in locals() inside a module- or class-scope comprehension.

  • gh-105331: Raise ValueError if the delay argument to asyncio.sleep() is a NaN (matching time.sleep()).

  • gh-105587: The runtime can’t guarantee that immortal objects will not be mutated by Extensions. Thus, this modifies _PyStaticObject_CheckRefcnt to warn instead of asserting.

  • gh-105564: Don’t include artificil newlines in the line attribute of tokens in the APIs of the tokenize module. Patch by Pablo Galindo

  • gh-105549: Tokenize separately NUMBER and NAME tokens that are not ambiguous. Patch by Pablo Galindo.

  • gh-105588: Fix an issue that could result in crashes when compiling malformed ast nodes.

  • gh-100987: Allow objects other than code objects as the “executable” in internal frames. In the long term, this can help tools like Cython and PySpy interact more efficiently. In the shorter term, it allows us to perform some optimizations more simply.

  • gh-105375: Fix bugs in the builtins module where exceptions could end up being overwritten.

  • gh-105375: Fix bug in the compiler where an exception could end up being overwritten.

  • gh-105375: Improve error handling in PyUnicode_BuildEncodingMap() where an exception could end up being overwritten.

  • gh-105486: Change the repr of ParamSpec list of args in types.GenericAlias.

  • gh-105678: Break the MAKE_FUNCTION instruction into two parts, MAKE_FUNCTION which makes the function and SET_FUNCTION_ATTRIBUTE which sets the attributes on the function. This makes the stack effect of MAKE_FUNCTION regular to ease optimization and code generation.

  • gh-105435: Fix spurious newline character if file ends on a comment without a newline. Patch by Pablo Galindo

  • gh-105390: Correctly raise tokenize.TokenError exceptions instead of SyntaxError for tokenize errors such as incomplete input. Patch by Pablo Galindo

  • gh-105259: Don’t include newline character for trailing NEWLINE tokens emitted in the tokenize module. Patch by Pablo Galindo

  • gh-104635: Eliminate redundant STORE_FAST instructions in the compiler. Patch by Donghee Na and Carl Meyer.

  • gh-105324: Fix the main function of the tokenize module when reading from sys.stdin. Patch by Pablo Galindo

  • gh-33092: Simplify and speed up interpreter for f-strings. Removes FORMAT_VALUE opcode. Add CONVERT_VALUE, FORMAT_SIMPLE and FORMAT_WITH_SPEC opcode. Compiler emits more efficient sequence for each format expression.

  • gh-105229: Remove remaining two-codeunit superinstructions. All remaining superinstructions only take a single codeunit, simplifying instrumentation and quickening.

  • gh-105235: Prevent out-of-bounds memory access during mmap.find() calls.

  • gh-98963: Restore the ability for a subclass of property to define __slots__ or otherwise be dict-less by ignoring failures to set a docstring on such a class. This behavior had regressed in 3.12beta1. An AttributeError where there had not previously been one was disruptive to existing code.

  • gh-104812: The “pending call” machinery now works for all interpreters, not just the main interpreter, and runs in all threads, not just the main thread. Some calls are still only done in the main thread, ergo in the main interpreter. This change does not affect signal handling nor the existing public C-API (Py_AddPendingCall()), which both still only target the main thread. The new functionality is meant strictly for internal use for now, since consequences of its use are not well understood yet outside some very restricted cases. This change brings the capability in line with the intention when the state was made per-interpreter several years ago.

  • gh-105194: Do not escape with backslashes f-string format specifiers. Patch by Pablo Galindo

  • gh-105229: Replace some dynamic superinstructions with single instruction equivalents.

  • gh-105162: Fixed bug in generator.close()/throw() where an inner iterator would be ignored when the outer iterator was instrumented.

  • gh-105164: Ensure annotations are set up correctly if the only annotation in a block is within a match block. Patch by Jelle Zijlstra.

  • gh-105148: Make _PyASTOptimizeState internal to ast_opt.c. Make _PyAST_Optimize take two integers instead of a pointer to this struct. This avoids the need to include pycore_compile.h in ast_opt.c.

  • gh-104799: Attributes of ast nodes that are lists now default to the empty list if omitted. This means that some code that previously raised TypeError when the AST node was used will now proceed with the empty list instead. Patch by Jelle Zijlstra.

  • gh-105111: Remove the old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

  • gh-105035: Fix super() calls on types with custom tp_getattro implementation (e.g. meta-types.)

  • gh-105017: Show CRLF lines in the tokenize string attribute in both NL and NEWLINE tokens. Patch by Marta Gómez.

  • gh-105013: Fix handling of multiline parenthesized lambdas in inspect.getsource(). Patch by Pablo Galindo

  • gh-105017: Do not include an additional final NL token when parsing files having CRLF lines. Patch by Marta Gómez.

  • gh-104976: Ensure that trailing DEDENT tokenize.TokenInfo objects emitted by the tokenize module are reported as in Python 3.11. Patch by Pablo Galindo

  • gh-104972: Ensure that the line attribute in tokenize.TokenInfo objects in the tokenize module are always correct. Patch by Pablo Galindo

  • gh-104955: Fix signature for the new __release_buffer__() slot. Patch by Jelle Zijlstra.

  • gh-104690: Starting new threads and process creation through os.fork() during interpreter shutdown (such as from atexit handlers) is no longer supported. It can lead to race condition between the main Python runtime thread freeing thread states while internal threading routines are trying to allocate and use the state of just created threads. Or forked children trying to use the mid-shutdown runtime and thread state in the child process.

  • gh-104879: Fix crash when accessing the __module__ attribute of type aliases defined outside a module. Patch by Jelle Zijlstra.

  • gh-104825: Tokens emitted by the tokenize module do not include an implicit \n character in the line attribute anymore. Patch by Pablo Galindo

  • gh-104770: If a generator returns a value upon being closed, the value is now returned by generator.close().

  • gh-89091: Raise RuntimeWarning for unawaited async generator methods like asend(), athrow() and aclose(). Patch by Kumar Aditya.

  • gh-96663: Add a better, more introspect-able error message when setting attributes on classes without a __dict__ and no slot member for the attribute.

  • gh-93627: Update the Python pickle module implementation to match the C implementation of the pickle module. For objects setting reduction methods like __reduce_ex__() or __reduce__() to None, pickling will result in a TypeError.

  • gh-101006: Improve error handling when read marshal data.

  • gh-91095: Specializes calls to most Python classes. Specifically, any class that inherits from object, or another Python class, and does not override __new__.

    The specialized instruction does the following:

    1. Creates the object (by calling object.__new__)

    2. Pushes a shim frame to the frame stack (to cleanup after __init__)

    3. Pushes the frame for __init__ to the frame stack

    Speeds up the instantiation of most Python classes.

Library

  • gh-109649: multiprocessing, concurrent.futures, compileall: Replace os.cpu_count() with os.process_cpu_count() to select the default number of worker threads and processes. Get the CPU affinity if supported. Patch by Victor Stinner.

  • gh-110150: Fix base case handling in statistics.quantiles. Now allows a single data point.

  • gh-110036: On Windows, multiprocessing Popen.terminate() now catchs PermissionError and get the process exit code. If the process is still running, raise again the PermissionError. Otherwise, the process terminated as expected: store its exit code. Patch by Victor Stinner.

  • gh-110038: Fixed an issue that caused KqueueSelector.select() to not return all the ready events in some cases when a file descriptor is registered for both read and write.

  • gh-110045: Update the symtable module to support the new scopes introduced by PEP 695.

  • gh-109631: re functions such as re.findall(), re.split(), re.search() and re.sub() which perform short repeated matches can now be interrupted by user.

  • gh-109818: Fix reprlib.recursive_repr() not copying __type_params__ from decorated function.

  • gh-109047: concurrent.futures: The executor manager thread now catches exceptions when adding an item to the call queue. During Python finalization, creating a new thread can now raise RuntimeError. Catch the exception and call terminate_broken() in this case. Patch by Victor Stinner.

  • gh-109782: Ensure the signature of os.path.isdir() is identical on all platforms. Patch by Amin Alaee.

  • gh-109653: Improve import time of functools by around 13%. Patch by Alex Waygood.

  • gh-109653: Reduce the import time of enum by over 50%. Patch by Alex Waygood.

  • gh-109593: Avoid deadlocking on a reentrant call to the multiprocessing resource tracker. Such a reentrant call, though unlikely, can happen if a GC pass invokes the finalizer for a multiprocessing object such as SemLock.

  • gh-109653: Reduce the import time of typing by around a third. Patch by Alex Waygood.

  • gh-109649: Add os.process_cpu_count() function to get the number of logical CPUs usable by the calling thread of the current process. Patch by Victor Stinner.

  • gh-74481: Add set_error_mode related constants in msvcrt module in Python debug build.

  • gh-109613: Fix os.stat() and os.DirEntry.stat(): check for exceptions. Previously, on Python built in debug mode, these functions could trigger a fatal Python error (and abort the process) when a function succeeded with an exception set. Patch by Victor Stinner.

  • gh-109599: Expose the type of PyCapsule objects as types.CapsuleType.

  • gh-109109: You can now get the raw TLS certificate chains from TLS connections via ssl.SSLSocket.get_verified_chain() and ssl.SSLSocket.get_unverified_chain() methods.

    Contributed by Mateusz Nowak.

  • gh-109559: Update unicodedata database to Unicode 15.1.0.

  • gh-109543: Remove unnecessary hasattr() check during typing.TypedDict creation.

  • gh-109495: Remove unnecessary extra __slots__ in datetime's pure python implementation to reduce memory size, as they are defined in the superclass. Patch by James Hilton-Balfe

  • gh-109461: logging: Use a context manager for lock acquisition.

  • gh-109096: http.server.CGIHTTPRequestHandler has been deprecated for removal in 3.15. Its design is old and the web world has long since moved beyond CGI.

  • gh-109375: The pdb alias command now prevents registering aliases without arguments.

  • gh-109319: Deprecate the dis.HAVE_ARGUMENT field in favour of dis.hasarg.

  • gh-107219: Fix a race condition in concurrent.futures. When a process in the process pool was terminated abruptly (while the future was running or pending), close the connection write end. If the call queue is blocked on sending bytes to a worker process, closing the connection write end interrupts the send, so the queue can be closed. Patch by Victor Stinner.

  • gh-66143: The codecs.CodecInfo object has been made copyable and pickleable. Patched by Robert Lehmann and Furkan Onder.

  • gh-109187: pathlib.Path.resolve() now treats symlink loops like other errors: in strict mode, OSError is raised, and in non-strict mode, no exception is raised.

  • gh-50644: Attempts to pickle or create a shallow or deep copy of codecs streams now raise a TypeError. Previously, copying failed with a RecursionError, while pickling produced wrong results that eventually caused unpickling to fail with a RecursionError.

  • gh-109174: Add support of types.SimpleNamespace in copy.replace().

  • gh-109164: pdb: Replace getopt with argparse for parsing command line arguments.

  • gh-108987: Fix _thread.start_new_thread() race condition. If a thread is created during Python finalization, the newly spawned thread now exits immediately instead of trying to access freed memory and lead to a crash. Patch by Victor Stinner.

  • gh-108682: Enum: require names=() or type=... to create an empty enum using the functional syntax.

  • gh-109033: Exceptions raised by os.utime builtin function now include the related filename

  • gh-108843: Fix an issue in ast.unparse() when unparsing f-strings containing many quote types.

  • gh-108469: ast.unparse() now supports new f-string syntax introduced in Python 3.12. Note that the f-string quotes are reselected for simplicity under the new syntax. (Patch by Steven Sun)

  • gh-108751: Add copy.replace() function which allows to create a modified copy of an object. It supports named tuples, dataclasses, and many other objects.

  • gh-108682: Enum: raise TypeError if super().__new__() is called from a custom __new__.

  • gh-108278: Deprecate passing the callback callable by keyword for the following sqlite3.Connection APIs:

    The affected parameters will become positional-only in Python 3.15.

    Patch by Erlend E. Aasland.

  • gh-105829: Fix concurrent.futures.ProcessPoolExecutor deadlock

  • gh-108295: Fix crashes related to use of weakrefs on typing.TypeVar.

  • gh-108463: Make expressions/statements work as expected in pdb

  • gh-107811: tarfile: extraction of members with overly large UID or GID (e.g. on an OS with 32-bit id_t) now fails in the same way as failing to set the ID.

  • gh-64662: Fix support for virtual tables in sqlite3.Connection.iterdump(). Patch by Aviv Palivoda.

  • gh-108111: Fix a regression introduced in gh-101251 for 3.12, resulting in an incorrect offset calculation in gzip.GzipFile.seek().

  • gh-108294: time.sleep() now raises an auditing event.

  • gh-108278: Deprecate passing name, number of arguments, and the callable as keyword arguments, for the following sqlite3.Connection APIs:

    The affected parameters will become positional-only in Python 3.15.

    Patch by Erlend E. Aasland.

  • gh-108322: Speed-up NormalDist.samples() by using the inverse CDF method instead of calling random.gauss().

  • gh-83417: Add the ability for venv to create a .gitignore file which causes the created environment to be ignored by Git. It is on by default when venv is called via its CLI.

  • gh-105736: Harmonized the pure Python version of OrderedDict with the C version. Now, both versions set up their internal state in __new__. Formerly, the pure Python version did the set up in __init__.

  • gh-108083: Fix bugs in the constructor of sqlite3.Connection and sqlite3.Connection.close() where exceptions could be leaked. Patch by Erlend E. Aasland.

  • gh-107932: Fix dis module to properly report and display bytecode that do not have source lines.

  • gh-105539: sqlite3 now emits an ResourceWarning if a sqlite3.Connection object is not closed explicitly. Patch by Erlend E. Aasland.

  • gh-107995: The __module__ attribute on instances of functools.cached_property is now set to the name of the module in which the cached_property is defined, rather than “functools”. This means that doctests in cached_property docstrings are now properly collected by the doctest module. Patch by Tyler Smart.

  • gh-107963: Fix multiprocessing.set_forkserver_preload() to check the given list of modules names. Patch by Donghee Na.

  • gh-106242: Fixes os.path.normpath() to handle embedded null characters without truncating the path.

  • gh-81555: xml.dom.minidom now only quotes " in attributes.

  • gh-50002: xml.dom.minidom now preserves whitespaces in attributes.

  • gh-93057: Passing more than one positional argument to sqlite3.connect() and the sqlite3.Connection constructor is deprecated. The remaining parameters will become keyword-only in Python 3.15. Patch by Erlend E. Aasland.

  • gh-76913: Add merge_extra parameter/feature to logging.LoggerAdapter

  • gh-107913: Fix possible losses of errno and winerror values in OSError exceptions if they were cleared or modified by the cleanup code before creating the exception object.

  • gh-107845: tarfile.data_filter() now takes the location of symlinks into account when determining their target, so it will no longer reject some valid tarballs with LinkOutsideDestinationError.

  • gh-107812: Extend socket’s netlink support to the FreeBSD platform.

  • gh-107805: Fix signatures of module-level generated functions in turtle.

  • gh-107782: pydoc is now able to show signatures which are not representable in Python, e.g. for getattr and dict.pop.

  • gh-56166: Deprecate passing optional arguments maxsplit, count and flags in module-level functions re.split(), re.sub() and re.subn() as positional. They should only be passed by keyword.

  • gh-107710: Speed up logging.getHandlerNames().

  • gh-107715: Fix doctest.DocTestFinder.find() in presence of class names with special characters. Patch by Gertjan van Zwieten.

  • gh-100814: Passing a callable object as an option value to a Tkinter image now raises the expected TclError instead of an AttributeError.

  • gh-72684: Add tkinter widget methods: tk_busy_hold(), tk_busy_configure(), tk_busy_cget(), tk_busy_forget(), tk_busy_current(), and tk_busy_status().

  • gh-106684: Raise ResourceWarning when asyncio.StreamWriter is not closed leading to memory leaks. Patch by Kumar Aditya.

  • gh-107077: Seems that in some conditions, OpenSSL will return SSL_ERROR_SYSCALL instead of SSL_ERROR_SSL when a certification verification has failed, but the error parameters will still contain ERR_LIB_SSL and SSL_R_CERTIFICATE_VERIFY_FAILED. We are now detecting this situation and raising the appropiate ssl.SSLCertVerificationError. Patch by Pablo Galindo

  • gh-107576: Fix types.get_original_bases() to only return __orig_bases__ if it is present on cls directly. Patch by James Hilton-Balfe.

  • gh-105481: Remove opcode.is_pseudo, opcode.MIN_PSEUDO_OPCODE and opcode.MAX_PSEUDO_OPCODE, which were added in 3.12, were never documented and were not intended to be used externally.

  • gh-105481: opcode.ENABLE_SPECIALIZATION (which was added in 3.12 but never documented or intended for external usage) is moved to _opcode.ENABLE_SPECIALIZATION where tests can access it.

  • gh-107396: tarfiles; Fixed use before assignment of self.exception for gzip decompression

  • gh-107409: Set __wrapped__ attribute in reprlib.recursive_repr().

  • gh-107406: Implement new __repr__() method for struct.Struct. Now it returns Struct(<format repr>).

  • gh-107369: Optimize textwrap.indent(). It is ~30% faster for large input. Patch by Inada Naoki.

  • gh-78722: Fix issue where pathlib.Path.iterdir() did not raise OSError until iterated.

  • gh-105578: Deprecate typing.AnyStr in favor of the new Type Parameter syntax. See PEP 695.

  • gh-62519: Make gettext.pgettext() search plural definitions when translation is not found.

  • gh-107089: Shelves opened with shelve.open() have a much faster clear() method. Patch by James Cave.

  • gh-82500: Fix overflow on 32-bit systems with asyncio os.sendfile() implemention.

  • gh-83006: Document behavior of shutil.disk_usage() for non-mounted filesystems on Unix.

  • gh-65495: Use lowercase mail from and rcpt to in smptlib.SMTP.

  • gh-106186: Do not report MultipartInvariantViolationDefect defect when the email.parser.Parser class is used to parse emails with headersonly=True.

  • gh-105002: Fix invalid result from PurePath.relative_to() method when attempting to walk a “..” segment in other with walk_up enabled. A ValueError exception is now raised in this case.

  • gh-106739: Add the rtype_cache to the warning message (as an addition to the type of leaked objects and the number of leaked objects already included in the message) to make debugging leaked objects easier when the multiprocessing resource tracker process finds leaked objects at shutdown. This helps more quickly identify what was leaked and/or why the leaked object was not properly cleaned up.

  • gh-106751: Optimize SelectSelector.select() for many iteration case. Patch By Donghee Na.

  • gh-106751: Optimize _PollLikeSelector.select() for many iteration case.

  • gh-106751: Optimize KqueueSelector.select() for many iteration case. Patch By Donghee Na.

  • gh-106831: Fix potential missing NULL check of d2i_SSL_SESSION result in _ssl.c.

  • gh-105481: The various opcode lists in the dis module are now generated from bytecodes.c instead of explicitly constructed in opcode.py.

  • gh-106727: Make inspect.getsource() smarter for class for same name definitions

  • gh-106789: Remove import of pprint from sysconfig.

  • gh-105726: Added __slots__ to contextlib.AbstractContextManager and contextlib.AbstractAsyncContextManager so that child classes can use __slots__.

  • gh-106774: Update the bundled copy of pip to version 23.2.1.

  • gh-106751: selectors: Optimize EpollSelector.select() code by moving some code outside of the loop.

  • gh-106752: Fixed several bugs in zipfile.Path, including: in zipfile.Path.match(), Windows separators are no longer honored (and never were meant to be); Fixed name/suffix/suffixes/stem operations when no filename is present and the Path is not at the root of the zipfile; Reworked glob for performance and more correct matching behavior.

  • gh-105293: Remove call to SSL_CTX_set_session_id_context during client side context creation in the ssl module.

  • gh-106734: Disable tab completion in multiline mode of pdb

  • gh-105481: Expose opcode metadata through _opcode.

  • gh-106670: Add the new exceptions command to the Pdb debugger. It makes it possible to move between chained exceptions when using post mortem debugging.

  • gh-106602: Add __copy__ and __deepcopy__ in enum

  • gh-106664: selectors: Add _SelectorMapping.get() method and optimize _SelectorMapping.__getitem__().

  • gh-106628: Speed up parsing of emails by about 20% by not compiling a new regular expression for every single email.

  • gh-89427: Set the environment variable VIRTUAL_ENV_PROMPT at venv activation, even when VIRTUAL_ENV_DISABLE_PROMPT is set.

  • gh-106530: Revert a change to colorsys.rgb_to_hls() that caused division by zero for certain almost-white inputs. Patch by Terry Jan Reedy.

  • gh-106584: Fix exit code for unittest if all tests are skipped. Patch by Egor Eliseev.

  • gh-106566: Optimize (?!) (pattern which alwais fails) in regular expressions.

  • gh-106554: selectors: Reduce Selector overhead by using a dict.get() to lookup file descriptors.

  • gh-106558: Remove ref cycle in callers of convert_to_error() by deleting result from scope in a finally block.

  • gh-100502: Add pathlib.PurePath.pathmod class attribute that stores the implementation of os.path used for low-level path operations: either posixpath or ntpath.

  • gh-106527: Reduce overhead to add and remove asyncio readers and writers.

  • gh-106524: Fix crash in _sre.template() with templates containing invalid group indices.

  • gh-106531: Removed _legacy and the names it provided from importlib.resources: Resource, contents, is_resource, open_binary, open_text, path, read_binary, and read_text.

  • gh-106052: re module: fix the matching of possessive quantifiers in the case of a subpattern containing backtracking.

  • gh-106510: Improve debug output for atomic groups in regular expressions.

  • gh-106503: Fix ref cycle in asyncio._SelectorSocketTransport by removing _write_ready in close.

  • gh-105497: Fix flag mask inversion when unnamed flags exist.

  • gh-90876: Prevent multiprocessing.spawn from failing to import in environments where sys.executable is None. This regressed in 3.11 with the addition of support for path-like objects in multiprocessing.

  • gh-106403: Instances of typing.TypeVar, typing.ParamSpec, typing.ParamSpecArgs, typing.ParamSpecKwargs, and typing.TypeVarTuple once again support weak references, fixing a regression introduced in Python 3.12.0 beta 1. Patch by Jelle Zijlstra.

  • gh-89812: Add private pathlib._PathBase class, which provides experimental support for virtual filesystems, and may be made public in a future version of Python.

  • gh-106292: Check for an instance-dict cached value in the __get__() method of functools.cached_property(). This better matches the pre-3.12 behavior and improves compatibility for users subclassing functools.cached_property() and adding a __set__() method.

  • gh-106350: Detect possible memory allocation failure in the libtommath function mp_init() used by the _tkinter module.

  • gh-106330: Fix incorrect matching of empty paths in pathlib.PurePath.match(). This bug was introduced in Python 3.12.0 beta 1.

  • gh-106309: Deprecate typing.no_type_check_decorator(). No major type checker ever added support for this decorator. Patch by Alex Waygood.

  • gh-102541: Make pydoc.doc catch bad module ImportError when output stream is not None.

  • gh-106263: Fix crash when calling repr with a manually constructed SignalDict object. Patch by Charlie Zhao.

  • gh-106236: Replace assert statements with raise RuntimeError in threading, so that _DummyThread cannot be joined even with -OO.

  • gh-106238: Fix rare concurrency bug in lock acquisition by the logging package.

  • gh-106152: Added PY_THROW event hook for cProfile for generators

  • gh-106075: Added asyncio.taskgroups.__all__ to asyncio.__all__ for export in star imports.

  • gh-104527: Zipapp will now skip over apending an archive to itself.

  • gh-106046: Improve the error message from os.fspath() if called on an object where __fspath__ is set to None. Patch by Alex Waygood.

  • gh-105987: Fix crash due to improper reference counting in asyncio eager task factory internal routines.

  • gh-105974: Fix bug where a typing.Protocol class that had one or more non-callable members would raise TypeError when issubclass() was called against it, even if it defined a custom __subclasshook__ method. The behaviour in Python 3.11 and lower – which has now been restored – was not to raise TypeError in these situations if a custom __subclasshook__ method was defined. Patch by Alex Waygood.

  • gh-96145: Reverted addition of json.AttrDict.

  • gh-89812: Add pathlib.UnsupportedOperation, which is raised instead of NotImplementedError when a path operation isn’t supported.

  • gh-105808: Fix a regression introduced in gh-101251 for 3.12, causing gzip.GzipFile.flush() to not flush the compressor (nor pass along the zip_mode argument).

  • gh-105481: stack_effect() no longer raises an exception if an oparg is provided for an opcode that doesn’t use its arg, or when it is not provided for an opcode that does use it. In the latter case, the stack effect is returned for oparg=0.

  • gh-104799: Enable ast.unparse() to unparse function and class definitions created without the new type_params field from PEP 695. Patch by Jelle Zijlstra.

  • gh-105793: Add follow_symlinks keyword-only argument to pathlib.Path.is_dir() and is_file(), defaulting to True.

  • gh-105570: Deprecate two methods of creating typing.TypedDict classes with 0 fields using the functional syntax: TD = TypedDict("TD") and TD = TypedDict("TD", None). Both will be disallowed in Python 3.15. To create a TypedDict class with 0 fields, either use class TD(TypedDict): pass or TD = TypedDict("TD", {}).

  • gh-105745: Fix webbrowser.Konqueror.open method.

  • gh-105733: ctypes: Deprecate undocumented ctypes.SetPointerType() and ctypes.ARRAY() functions. Patch by Victor Stinner.

  • gh-105687: Remove deprecated re.template, re.T, re.TEMPLATE, sre_constans.SRE_FLAG_TEMPLATE.

  • gh-105684: Supporting asyncio.Task.set_name() is now mandatory for third party task implementations. The undocumented _set_task_name() function (deprecated since 3.8) has been removed. Patch by Kumar Aditya.

  • gh-105375: Fix a bug in _Unpickler_SetInputStream() where an exception could end up being overwritten in case of failure.

  • gh-105626: Change the default return value of http.client.HTTPConnection.get_proxy_response_headers() to be None and not {}.

  • gh-105375: Fix bugs in sys where exceptions could end up being overwritten because of deferred error handling.

  • gh-105605: Harden pyexpat error handling during module initialisation to prevent exceptions from possibly being overwritten, and objects from being dereferenced twice.

  • gh-105375: Fix bug in decimal where an exception could end up being overwritten.

  • gh-105375: Fix bugs in _datetime where exceptions could be overwritten in case of module initialisation failure.

  • gh-105375: Fix bugs in _ssl initialisation which could lead to leaked references and overwritten exceptions.

  • gh-105375: Fix a bug in array.array where an exception could end up being overwritten.

  • gh-105375: Fix bugs in _ctypes where exceptions could end up being overwritten.

  • gh-105375: Fix a bug in the posix module where an exception could be overwritten.

  • gh-105375: Fix bugs in _elementtree where exceptions could be overwritten.

  • gh-105375: Fix bugs in zoneinfo where exceptions could be overwritten.

  • gh-105375: Fix bugs in errno where exceptions could be overwritten.

  • gh-105566: Deprecate creating a typing.NamedTuple class using keyword arguments to denote the fields (NT = NamedTuple("NT", x=int, y=str)). This will be disallowed in Python 3.15. Use the class-based syntax or the functional syntax instead.

    Two methods of creating NamedTuple classes with 0 fields using the functional syntax are also deprecated, and will be disallowed in Python 3.15: NT = NamedTuple("NT") and NT = NamedTuple("NT", None). To create a NamedTuple class with 0 fields, either use class NT(NamedTuple): pass or NT = NamedTuple("NT", []).

  • gh-105545: Remove deprecated in 3.11 webbrowser.MacOSXOSAScript._name attribute.

  • gh-105497: Fix flag inversion when alias/mask members exist.

  • gh-105509: typing.Annotated is now implemented as an instance of typing._SpecialForm rather than a class. This should have no user-facing impact for users of the typing module public API.

  • gh-105375: Fix bugs in pickle where exceptions could be overwritten.

  • gh-70303: Emit FutureWarning from pathlib.Path.glob() and rglob() if the given pattern ends with “**”. In a future Python release, patterns with this ending will match both files and directories. Add a trailing slash to only match directories.

  • gh-105375: Fix a bug in sqlite3 where an exception could be overwritten in the collation callback.

  • gh-105382: Remove cafile, capath and cadefault parameters of the urllib.request.urlopen() function, deprecated in Python 3.6. Patch by Victor Stinner.

  • gh-105376: logging: Remove undocumented and untested Logger.warn() and LoggerAdapter.warn() methods and logging.warn() function. Deprecated since Python 3.3, they were aliases to the logging.Logger.warning() method, logging.LoggerAdapter.warning() method and logging.warning() function. Patch by Victor Stinner.

  • gh-105332: Revert pickling method from by-name back to by-value.

  • gh-104554: Add RTSPS scheme support in urllib.parse

  • gh-105292: Add option to traceback.format_exception_only() to recurse into the nested exception of a BaseExceptionGroup.

  • gh-105280: Fix bug where isinstance([], collections.abc.Mapping) could evaluate to True if garbage collection happened at the wrong time. The bug was caused by changes to the implementation of typing.Protocol in Python 3.12.

  • gh-80480: array: Add 'w' typecode that represents Py_UCS4.

  • gh-105239: Fix longstanding bug where issubclass(object, typing.Protocol) would evaluate to True in some edge cases. Patch by Alex Waygood.

  • gh-104310: In the beta 1 release we added a utility function for extension module authors, to use when testing their module for support in multiple interpreters or under a per-interpreter GIL. The name of that function has changed from allowing_all_extensions to _incompatible_extension_module_restrictions. The default for the “disable_check” argument has change from True to False, to better match the new function name.

  • gh-105080: Fixed inconsistent signature on derived classes for inspect.signature()

  • gh-105144: Fix a recent regression in the typing module. The regression meant that doing class Foo(X, typing.Protocol), where X was a class that had abc.ABCMeta as its metaclass, would then cause subsequent isinstance(1, X) calls to erroneously raise TypeError. Patch by Alex Waygood.

  • gh-62948: The io.IOBase finalizer now logs the close() method errors with sys.unraisablehook. Previously, errors were ignored silently by default, and only logged in Python Development Mode or on Python built on debug mode. Patch by Victor Stinner.

  • gh-105096: wave: Deprecate the getmark(), setmark() and getmarkers() methods of the wave.Wave_read and wave.Wave_write classes. They will be removed in Python 3.15. Patch by Victor Stinner.

  • gh-104992: Remove the untested and undocumented unittest.TestProgram.usageExit() method, deprecated in Python 3.11. Patch by Hugo van Kemenade.

  • gh-104996: Improve performance of pathlib.PurePath initialisation by deferring joining of paths when multiple arguments are given.

  • gh-101588: Deprecate undocumented copy/deepcopy/pickle support for itertools.

  • gh-103631: Fix pathlib.PurePosixPath(pathlib.PureWindowsPath(...)) not converting path separators to restore 3.11 compatible behavior.

  • gh-104947: Make comparisons between pathlib.PureWindowsPath objects consistent across Windows and Posix to match 3.11 behavior.

  • gh-104773: PEP 594: Remove the audioop module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the aifc module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the uu module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104935: Fix bugs with the interaction between typing.runtime_checkable() and typing.Generic that were introduced by the PEP 695 implementation. Patch by Jelle Zijlstra.

  • gh-104773: PEP 594: Remove the crypt module and its private _crypt extension, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the nis module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104898: Add missing __slots__ to os.PathLike.

  • gh-104773: PEP 594: Remove the xdrlib module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the nntplib module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104886: Remove the undocumented configparser.LegacyInterpolation class, deprecated in the docstring since Python 3.2, and with a deprecation warning since Python 3.11. Patch by Hugo van Kemenade.

  • gh-104786: Remove kwargs-based typing.TypedDict creation

  • gh-104876: Remove the turtle.RawTurtle.settiltangle() method, deprecated in docs since Python 3.1 and with a deprecation warning since Python 3.11. Patch by Hugo van Kemenade.

  • gh-104773: PEP 594: Removed the msilib package, deprecated in Python 3.11.

  • gh-104773: PEP 594: Remove the spwd module, deprecated in Python 3.11: the python-pam project can be used instead. Patch by Victor Stinner.

  • gh-75552: Removed the tkinter.tix module, deprecated since Python 3.6.

  • gh-104773: PEP 594: Remove the chunk module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the mailcap module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the sunau module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104780: PEP 594: Remove the ossaudiodev module, deprecated in Python 3.11. Patch Victor Stinner.

  • gh-104773: PEP 594: Remove the pipes module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104873: Add typing.get_protocol_members() to return the set of members defining a typing.Protocol. Add typing.is_protocol() to check whether a class is a typing.Protocol. Patch by Jelle Zijlstra.

  • gh-104874: Document the __name__ and __supertype__ attributes of typing.NewType. Patch by Jelle Zijlstra.

  • gh-104835: Removed the following unittest functions, deprecated in Python 3.11:

    • unittest.findTestCases()

    • unittest.makeSuite()

    • unittest.getTestCaseNames()

    Use TestLoader methods instead:

    Patch by Hugo van Kemenade.

  • gh-104804: Remove the untested and undocumented webbrowser MacOSX class, deprecated in Python 3.11. Patch by Hugo van Kemenade.

  • gh-83863: Support for using pathlib.Path objects as context managers has been removed. Before Python 3.9, exiting the context manager marked a path as “closed”, which caused some (but not all!) methods to raise when called. Since Python 3.9, using a path as a context manager does nothing.

  • gh-104799: Adjust the location of the (see PEP 695) type_params field on ast.ClassDef, ast.AsyncFunctionDef, and ast.FunctionDef to better preserve backward compatibility. Patch by Jelle Zijlstra

  • gh-104797: Allow typing.Protocol classes to inherit from collections.abc.Buffer. Patch by Jelle Zijlstra.

  • gh-104783: Remove locale.resetlocale() function deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104780: Remove the 2to3 program and the lib2to3 module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the telnetlib module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the imghdr module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the cgi` and cgitb modules, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104773: PEP 594: Remove the sndhdr module, deprecated in Python 3.11. Patch by Victor Stinner.

  • gh-104372: On Linux where subprocess can use the vfork() syscall for faster spawning, prevent the parent process from blocking other threads by dropping the GIL while it waits for the vfork’ed child process exec() outcome. This prevents spawning a binary from a slow filesystem from blocking the rest of the application.

  • gh-99108: We now release the GIL around built-in hashlib computations of reasonable size for the SHA families and MD5 hash functions, matching what our OpenSSL backed hash computations already does.

  • gh-102613: Improve performance of pathlib.Path.glob() when expanding a pattern with a non-terminal “**” component by filtering walked paths through a regular expression, rather than calling os.scandir() more than once on each directory.

  • gh-104399: Prepare the _tkinter module for building with Tcl 9.0 and future libtommath by replacing usage of deprecated functions mp_to_unsigned_bin_n() and mp_unsigned_bin_size() when necessary.

  • gh-102676: Add fields start_offset, cache_offset, end_offset, baseopname, baseopcode, jump_target and oparg to dis.Instruction.

  • gh-103558: Fixed parent argument validation mechanism of argparse. Improved test coverage.

  • gh-103464: Provide helpful usage messages when parsing incorrect pdb commands.

  • gh-103384: Generalize the regex pattern BaseConfigurator.INDEX_PATTERN to allow spaces and non-alphanumeric characters in keys.

  • gh-103124: Added multiline statement support for pdb

  • gh-101162: Forbid using builtins.issubclass() with types.GenericAlias as the first argument.

  • gh-103200: Fix cache repopulation semantics of zipimport.invalidate_caches(). The cache is now repopulated upon retrieving files with an invalid cache, not when the cache is invalidated.

  • gh-100061: Fix a bug that causes wrong matches for regular expressions with possessive qualifier.

  • gh-77609: Add follow_symlinks argument to pathlib.Path.glob() and rglob(), defaulting to false.

  • gh-102541: Hide traceback in help() prompt, when import failed.

  • gh-102120: Added a stream mode to tarfile that allows for reading archives without caching info about the inner files.

  • gh-102029: Deprecate passing any arguments to threading.RLock().

  • gh-88233: Refactored zipfile._strip_extra to use higher level abstactions for extras instead of a heavy-state loop.

  • gh-102024: Reduce calls of _idle_semaphore.release() in concurrent.futures.thread._worker().

  • gh-73435: Add support for recursive wildcards in pathlib.PurePath.match().

  • gh-84867: unittest.TestLoader no longer loads test cases from exact unittest.TestCase and unittest.FunctionTestCase classes.

  • gh-99203: Restore following CPython <= 3.10.5 behavior of shutil.make_archive(): do not create an empty archive if root_dir is not a directory, and, in that case, raise FileNotFoundError or NotADirectoryError regardless of format choice. Beyond the brought-back behavior, the function may now also raise these exceptions in dry_run mode.

  • gh-80480: Emit DeprecationWarning for array’s 'u' type code, deprecated in docs since Python 3.3.

  • gh-94924: unittest.mock.create_autospec() now properly returns coroutine functions compatible with inspect.iscoroutinefunction()

  • gh-94777: Fix hanging multiprocessing ProcessPoolExecutor when a child process crashes while data is being written in the call queue.

  • gh-92871: Remove the typing.io and typing.re namespaces, deprecated since Python 3.8. All items are still available from the main typing module.

  • bpo-43633: Improve the textual representation of IPv4-mapped IPv6 addresses (RFC 4291 Sections 2.2, 2.5.5.2) in ipaddress. Patch by Oleksandr Pavliuk.

  • bpo-44850: Improve performance of operator.methodcaller() using the PEP 590 vectorcall convention. Patch by Anthony Lee and Pieter Eendebak.

  • bpo-44185: unittest.mock.mock_open() will call the close() method of the file handle mock when it is exiting from the context manager. Patch by Samet Yaslan.

  • bpo-40988: Improve performance of functools.singledispatchmethod by caching the generated dispatch wrapper. Optimization suggested by frederico. Patch by @mental32, Alex Waygood and Pieter Eendebak.

  • bpo-41768: unittest.mock speccing no longer calls class properties. Patch by Melanie Witt.

  • bpo-18319: Ensure gettext(msg) retrieve translations even if a plural form exists. In other words: gettext(msg) == ngettext(msg, '', 1).

  • bpo-17013: Add ThreadingMock to unittest.mock that can be used to create Mock objects that can wait until they are called. Patch by Karthikeyan Singaravelan and Mario Corchero.

Documentation

Tests

  • gh-110152: Remove Tools/scripts/run_tests.py and make hostrunnertest. Just run ./python -m test --slow-ci, make buildbottest or make test instead. Python test runner (regrtest) now handles cross-compilation and HOSTRUNNER. It also adds options to Python such fast -u -E -W default -bb when --fast-ci or --slow-ci option is used. Patch by Victor Stinner.

  • gh-110031: Skip test_threading tests using thread+fork if Python is built with Address Sanitizer (ASAN). Patch by Victor Stinner.

  • gh-110088: Fix test_asyncio timeouts: don’t measure the maximum duration, a test should not measure a CI performance. Only measure the minimum duration when a task has a timeout or delay. Add CLOCK_RES to test_asyncio.utils. Patch by Victor Stinner.

  • gh-109974: Fix race conditions in test_threading lock tests. Wait until a condition is met rather than using time.sleep() with a hardcoded number of seconds. Patch by Victor Stinner.

  • gh-110033: Fix test_interprocess_signal() of test_signal. Make sure that the subprocess.Popen object is deleted before the test raising an exception in a signal handler. Otherwise, Popen.__del__() can get the exception which is logged as Exception ignored in: ... and the test fails. Patch by Victor Stinner.

  • gh-109594: Fix test_timeout() of test_concurrent_futures.test_wait. Remove the future which may or may not complete depending if it takes longer than the timeout ot not. Keep the second future which does not complete before wait() timeout. Patch by Victor Stinner.

  • gh-109972: Split test_gdb.py file into a test_gdb package made of multiple tests, so tests can now be run in parallel. Patch by Victor Stinner.

  • gh-109566: regrtest: When --fast-ci or --slow-ci option is used, regrtest now replaces the current process with a new process to add -u -W default -bb -E options to Python. Patch by Victor Stinner.

  • gh-109748: Fix test_zippath_from_non_installed_posix() of test_venv: don’t copy __pycache__/ sub-directories, because they can be modified by other Python tests running in parallel. Patch by Victor Stinner.

  • gh-109739: regrtest: Fix reference leak check on Windows. Disable the load tracker on Windows in the reference leak check mode (-R option). Patch by Victor Stinner.

  • gh-109276: regrtest: When a test fails with “env changed” and the –rerun option is used, the test is now re-run in verbose mode in a fresh process. Patch by Victor Stinner.

  • gh-103053: Skip test_freeze_simple_script() of test_tools.test_freeze if Python is built with ./configure --enable-optimizations, which means with Profile Guided Optimization (PGO): it just makes the test too slow. The freeze tool is tested by many other CIs with other (faster) compiler flags. Patch by Victor Stinner.

  • gh-109580: Skip test_perf_profiler if Python is built with ASAN, MSAN or UBSAN sanitizer. Python does crash randomly in this test on such build. Patch by Victor Stinner.

  • gh-109566: regrtest: Add --fast-ci and --slow-ci options. --fast-ci uses a default timeout of 10 minutes and -u all,-cpu (skip slowest tests). --slow-ci uses a default timeout of 20 minues and -u all (run all tests). Patch by Victor Stinner.

  • gh-109425: libregrtest now decodes stdout of test worker processes with the “backslashreplace” error handler to log corrupted stdout, instead of failing with an error and not logging the stdout. Patch by Victor Stinner.

  • gh-109396: Fix test_socket.test_hmac_sha1() in FIPS mode. Use a longer key: FIPS mode requires at least of at least 112 bits. The previous key was only 32 bits. Patch by Victor Stinner.

  • gh-104736: Fix test_gdb on Python built with LLVM clang 16 on Linux ppc64le (ex: Fedora 38). Search patterns in gdb “bt” command output to detect when gdb fails to retrieve the traceback. For example, skip a test if Backtrace stopped: frame did not save the PC is found. Patch by Victor Stinner.

  • gh-109276: libregrtest now calls random.seed() before running each test file when -r/--randomize command line option is used. Moreover, it’s also called in worker processes. It should help to make tests more deterministic. Previously, it was only called once in the main process before running all test files and it was not called in worker processes. Patch by Victor Stinner.

  • gh-109276: libregrtest now uses a separated file descriptor to write test result as JSON. Previously, if a test wrote debug messages late around the JSON, the main test process failed to parse JSON. Patch by Victor Stinner.

  • gh-108996: Fix and enable test_msvcrt.

  • gh-109237: Fix test_site.test_underpth_basic() when the working directory contains at least one non-ASCII character: encode the ._pth file to UTF-8 and enable the UTF-8 Mode to use UTF-8 for the child process stdout. Patch by Victor Stinner.

  • gh-109230: Fix test_pyexpat.test_exception(): it can now be run from a directory different than Python source code directory. Before, the test failed in this case. Skip the test if Modules/pyexpat.c source is not available. Skip also the test on Python implementations other than CPython. Patch by Victor Stinner.

  • gh-108996: Add tests for msvcrt.

  • gh-109015: Fix test_asyncio, test_imaplib and test_socket tests on FreeBSD if the TCP blackhole is enabled (sysctl net.inet.tcp.blackhole). Skip the few tests which failed with ETIMEDOUT which such non standard configuration. Currently, the FreeBSD GCP image enables TCP and UDP blackhole (sysctl net.inet.tcp.blackhole=2 and sysctl net.inet.udp.blackhole=1). Patch by Victor Stinner.

  • gh-91960: Skip test_gdb if gdb is unable to retrieve Python frame objects: if a frame is <optimized out>. When Python is built with “clang -Og”, gdb can fail to retrive the frame parameter of _PyEval_EvalFrameDefault(). In this case, tests like py_bt() are likely to fail. Without getting access to Python frames, python-gdb.py is mostly clueless on retrieving the Python traceback. Moreover, test_gdb is no longer skipped on macOS if Python is built with Clang. Patch by Victor Stinner.

  • gh-108962: Skip test_tempfile.test_flags() if chflags() fails with “OSError: [Errno 45] Operation not supported” (ex: on FreeBSD 13). Patch by Victor Stinner.

  • gh-91960: FreeBSD 13.2 CI coverage for pull requests is now provided by Cirrus-CI (a hosted CI service that supports Linux, macOS, Windows, and FreeBSD).

  • gh-89392: Removed support of test_main() function in tests. They now always use normal unittest test runner.

  • gh-108851: Fix test_tomllib recursion tests for WASI buildbots: reduce the recursion limit and compute the maximum nested array/dict depending on the current available recursion limit. Patch by Victor Stinner.

  • gh-108851: Add get_recursion_available() and get_recursion_depth() functions to the test.support module. Patch by Victor Stinner.

  • gh-108834: Add --fail-rerun option option to regrtest: if a test failed when then passed when rerun in verbose mode, exit the process with exit code 2 (error), instead of exit code 0 (success). Patch by Victor Stinner.

  • gh-108834: Rename regrtest --verbose2 option (-w) to --rerun. Keep --verbose2 as a deprecated alias. Patch by Victor Stinner.

  • gh-108834: When regrtest reruns failed tests in verbose mode (./python -m test --rerun), tests are now rerun in fresh worker processes rather than being executed in the main process. If a test does crash or is killed by a timeout, the main process can detect and handle the killed worker process. Tests are rerun in parallel if the -jN option is used to run tests in parallel. Patch by Victor Stinner.

  • gh-108822: regrtest now computes statistics on all tests: successes, failures and skipped. test_netrc, test_pep646_syntax and test_xml_etree now return results in their test_main() function. Patch by Victor Stinner and Alex Waygood.

  • gh-108794: The doctest.DocTestRunner.run() method now counts the number of skipped tests. Add doctest.DocTestRunner.skips and doctest.TestResults.skipped attributes. Patch by Victor Stinner.

  • gh-108388: Convert test_concurrent_futures to a package of 7 sub-tests. Patch by Victor Stinner.

  • gh-108388: Split test_multiprocessing_fork, test_multiprocessing_forkserver and test_multiprocessing_spawn into test packages. Each package is made of 4 sub-tests: processes, threads, manager and misc. It allows running more tests in parallel and so reduce the total test duration. Patch by Victor Stinner.

  • gh-105776: Fix test_cppext when the C compiler command -std=c11 option: remove -std= options from the compiler command. Patch by Victor Stinner.

  • gh-107237: test_logging: Fix test_udp_reconnection() by increasing the timeout from 100 ms to 5 minutes (LONG_TIMEOUT). Patch by Victor Stinner.

  • gh-107178: Add the C API test for functions in the Mapping Protocol, the Sequence Protocol and some functions in the Object Protocol.

  • gh-106714: test_capi: Fix test_no_FatalError_infinite_loop() to no longer write a coredump, by using test.support.SuppressCrashReport. Patch by Victor Stinner.

  • gh-104090: Avoid creating a reference to the test object in collectedDurations().

  • gh-106752: Moved tests for zipfile.Path into Lib/test/test_zipfile/_path. Made zipfile._path a package.

  • gh-106690: Add .coveragerc to cpython repository for use with coverage package.

  • gh-101634: When running the Python test suite with -jN option, if a worker stdout cannot be decoded from the locale encoding report a failed testn so the exitcode is non-zero. Patch by Victor Stinner.

  • gh-105084: When the Python build is configured --with-wheel-pkg-dir, tests requiring the setuptools and wheel wheels will search for the wheels in WHEEL_PKG_DIR.

  • gh-81005: String tests are modified to reflect that str and unicode are merged in Python 3. Patch by Daniel Fortunov.

  • gh-103186: Suppress and assert expected RuntimeWarnings in test_sys_settrace.py

  • gh-69714: Add additional tests to calendar to achieve full test coverage.

Build

  • gh-109566: Remove make testall target: use make buildbottest instead. Patch by Victor Stinner.

  • gh-109740: The experimental --disable-gil configure flag now includes “t” (for “threaded”) in extension ABI tags.

  • gh-109054: Fix building the _testcapi extension on Linux AArch64 which requires linking to libatomic when <cpython/pyatomic.h> is used: the _Py_atomic_or_uint64() function requires libatomic __atomic_fetch_or_8() on this platform. The configure script now checks if linking to libatomic is needed and generates a new LIBATOMIC variable used to build the _testcapi extension. Patch by Victor Stinner.

  • gh-63760: Fix Solaris build: no longer redefine the gethostname() function. Solaris defines the function since 2005. Patch by Victor Stinner, original patch by Jakub Kulík.

  • gh-108740: Fix a race condition in make regen-all. The deepfreeze.c source and files generated by Argument Clinic are now generated or updated before generating “global objects”. Previously, some identifiers may miss depending on the order in which these files were generated. Patch by Victor Stinner.

  • gh-108634: Python built with configure --with-trace-refs (tracing references) is now ABI compatible with Python release build and debug build. Patch by Victor Stinner.

  • gh-108447: Fix x86_64 GNU/Hurd build

  • gh-107814: When calling find_python.bat with -q it did not properly silence the output of nuget. That is now fixed.

  • gh-105481: Remove the make target regen-opcode-targets, merge its work into regen-opcode which repeats most of the calculation. This simplifies the code for the build and reduces code duplication.

  • gh-106881: Check for linux/limits.h before including it in Modules/posixmodule.c.

  • gh-95855: Refactor platform triplet detection code and add detection for MIPS soft float and musl libc.

  • gh-106962: Detect MPI compilers in configure.

  • gh-106118: Fix compilation for platforms without O_CLOEXEC. The issue was introduced with Python 3.12b1 in gh-103295. Patch by Erlend Aasland.

  • gh-105875: SQLite 3.15.2 or newer is required to build the sqlite3 extension module. Patch by Erlend Aasland.

  • gh-90005: Fix a regression in configure where we could end up unintentionally linking with libbsd.

  • gh-102404: Document how to perform a WASI build on Linux. Also add Tools/wasm/build_wasi.sh as a reference implementation of the docs.

  • gh-89886: Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate !configure.

  • gh-104692: Include commoninstall as a prerequisite for bininstall

    This ensures that commoninstall is completed before bininstall is started when parallel builds are used (make -j install), and so the python3 symlink is only installed after all standard library modules are installed.

  • gh-101538: Add experimental wasi-threads support. Patch by Takashi Yamamoto.

Windows

  • gh-109991: Update Windows build to use OpenSSL 3.0.11.

  • gh-106242: Fixes realpath() to behave consistently when passed a path containing an embedded null character on Windows. In strict mode, it now raises OSError instead of the unexpected ValueError, and in non-strict mode will make the path absolute.

  • gh-106844: Fix integer overflow and truncating by the null character in _winapi.LCMapStringEx() which affects ntpath.normcase().

  • gh-105436: Ensure that an empty environment block is terminated by two null characters, as is required by Windows.

  • gh-105146: Updated the links at the end of the installer to point to Discourse rather than the mailing lists.

  • gh-103646: When installed from the Microsoft Store, pip no longer defaults to per-user installs. However, as the install directory is unwritable, it should automatically decide to do a per-user install anyway. This should resolve issues when pip is passed an option that conflicts with --user.

  • gh-88745: Improve performance of shutil.copy2() by using the operating system’s CopyFile2 function. This may result in subtle changes to metadata copied along with some files, bringing them in line with normal OS behavior.

  • gh-104820: Fixes stat() and related functions on file systems that do not support file ID requests. This includes FAT32 and exFAT.

  • gh-104803: Add os.path.isdevdrive() to detect whether a path is on a Windows Dev Drive. Returns False on platforms that do not support Dev Drive, and is absent on non-Windows platforms.

macOS

  • gh-109991: Update macOS installer to use OpenSSL 3.0.11.

  • gh-99079: Update macOS installer to use OpenSSL 3.0.9.

IDLE

  • gh-104719: Remove IDLE’s modification of tokenize.tabsize and test other uses of tokenize data and methods.

Tools/Demos

  • gh-109991: Update GitHub CI workflows to use OpenSSL 3.0.11 and multissltests to use 1.1.1w, 3.0.11, and 3.1.3.

  • gh-108494: Argument Clinic now has a partial support of the Limited API: see How to use the Limited C API. Patch by Victor Stinner.

  • gh-107704: It is now possible to deprecate passing keyword arguments for keyword-or-positional parameters with Argument Clinic, using the new / [from X.Y] syntax. (To be read as “positional-only from Python version X.Y”.) See How to deprecate passing parameters positionally or by keyword for more information.

  • gh-107880: Argument Clinic can now clone __init__() and __new__() methods.

  • gh-104683: Add --exclude option to Argument Clinic CLI.

  • gh-95065: Argument Clinic now supports overriding automatically generated signature by using directive @text_signature. See How to override the generated signature.

  • gh-107609: Fix duplicate module check in Argument Clinic. Previously, a duplicate definition would incorrectly be silently accepted. Patch by Erlend E. Aasland.

  • gh-107467: The Argument Clinic command-line tool now prints to stderr instead of stdout on failure.

  • gh-106970: Fix bugs in the Argument Clinic destination <name> clear command; the destination buffers would never be cleared, and the destination directive parser would simply continue to the fault handler after processing the command. Patch by Erlend E. Aasland.

  • gh-106706: Change bytecode syntax for families to remove redundant name matching pseudo syntax.

  • gh-106359: Argument Clinic now explicitly forbids “kwarg splats” in function calls used as annotations.

  • gh-103186: freeze now fetches CONFIG_ARGS from the original CPython instance the Makefile uses to call utility scripts. Patch by Ijtaba Hussain.

  • gh-95065: It is now possible to deprecate passing parameters positionally with Argument Clinic, using the new * [from X.Y] syntax. (To be read as “keyword-only from Python version X.Y”.) See How to deprecate passing parameters positionally or by keyword for more information. Patch by Erlend E. Aasland with help from Alex Waygood, Nikita Sobolev, and Serhiy Storchaka.

C API

Python 3.12.0 beta 1

Release date: 2023-05-22

Security

  • gh-99889: Fixed a security in flaw in uu.decode() that could allow for directory traversal based on the input if no out_file was specified.

  • gh-104049: Do not expose the local on-disk location in directory indexes produced by http.client.SimpleHTTPRequestHandler.

  • gh-99108: Upgrade built-in hashlib SHA3 implementation to a verified implementation from the HACL* project. Used when OpenSSL is not present or lacks SHA3.

  • gh-102153: urllib.parse.urlsplit() now strips leading C0 control and space characters following the specification for URLs defined by WHATWG in response to CVE-2023-24329. Patch by Illia Volochii.

Core and Builtins

  • gh-102856: Implement PEP 701 changes in the tokenize module. Patch by Marta Gómez Macías and Pablo Galindo Salgado

  • gh-104615: Fix wrong ordering of assignments in code like a, a = x, y. Contributed by Carl Meyer.

  • gh-104572: Improve syntax error message for invalid constructs in PEP 695 contexts and in annotations when from __future__ import annotations is active.

  • gh-104482: Fix three error handling bugs in ast.c’s validation of pattern matching statements.

  • gh-102818: Do not add a frame to the traceback in the sys.setprofile and sys.settrace trampoline functions. This ensures that frames are not duplicated if an exception is raised in the callback function, and ensures that frames are not omitted if a C callback is used and that does not add the frame.

  • gh-104405: Fix an issue where some bytecode instructions could ignore PEP 523 when “inlining” calls.

  • gh-103082: Change behavior of sys.monitoring.events.LINE events in sys.monitoring: Line events now occur when a new line is reached dynamically, instead of using a static approximation, as before. This makes the behavior very similar to that of “line” events in sys.settrace. This should ease porting of tools from 3.11 to 3.12.

  • gh-104263: Fix float("nan") to produce a quiet NaN on platforms (like MIPS) where the meaning of the signalling / quiet bit is inverted from its usual meaning. Also introduce a new macro Py_INFINITY matching C99’s INFINITY, and refactor internals to rely on C99’s NAN and INFINITY macros instead of hard-coding bit patterns for infinities and NaNs. Thanks Sebastian Berg.

  • gh-99113: Multi-phase init extension modules may now indicate that they support running in subinterpreters that have their own GIL. This is done by using Py_MOD_PER_INTERPRETER_GIL_SUPPORTED as the value for the Py_mod_multiple_interpreters module def slot. Otherwise the module, by default, cannot be imported in such subinterpreters. (This does not affect the main interpreter or subinterpreters that do not have their own GIL.) In addition to the isolation that multi-phase init already normally requires, support for per-interpreter GIL involves one additional constraint: thread-safety. If the module has external (linked) dependencies and those libraries have any state that isn’t thread-safe then the module must do the additional work to add thread-safety. This should be an uncommon case.

  • gh-99113: The GIL is now (optionally) per-interpreter. This is the fundamental change for PEP 684. This is all made possible by virtue of the isolated state of each interpreter in the process. The behavior of the main interpreter remains unchanged. Likewise, interpreters created using Py_NewInterpreter() are not affected. To get an interpreter with its own GIL, call Py_NewInterpreterFromConfig().

  • gh-104108: Multi-phase init extension modules may now indicate whether or not they actually support multiple interpreters. By default such modules are expected to support use in multiple interpreters. In the uncommon case that one does not, it may use the new Py_mod_multiple_interpreters module def slot. A value of 0 means the module does not support them. 1 means it does. The default is 1.

  • gh-104142: Fix an issue where list or tuple repetition could fail to respect PEP 683.

  • gh-104078: Improve the performance of PyObject_HasAttrString()

  • gh-104066: Improve the performance of hasattr() for module objects with a missing attribute.

  • gh-104028: Reduce object creation while calling callback function from gc. Patch by Donghee Na.

  • gh-104018: Disallow the “z” format specifier in %-format of bytes objects.

  • gh-102213: Fix performance loss when accessing an object’s attributes with __getattr__ defined.

  • gh-103895: Improve handling of edge cases in showing Exception.__notes__. Ensures that the messages always end with a newline and that string/bytes are not exploded over multiple lines. Patch by Carey Metcalfe.

  • gh-103907: Don’t modify the refcounts of known immortal objects (True, False, and None) in the main interpreter loop.

  • gh-103899: Provide a helpful hint in the TypeError message when accidentally calling a module object that has a callable attribute of the same name (such as dis.dis() or datetime.datetime).

  • gh-103845: Remove both line and instruction instrumentation before adding new ones for monitoring, to avoid newly added instrumentation being removed immediately.

  • gh-103763: Implement PEP 695, adding syntactic support for generic classes, generic functions, and type aliases.

    A new type X = ... syntax is added for type aliases, which resolves at runtime to an instance of the new class typing.TypeAliasType. The value is lazily evaluated and is accessible through the .__value__ attribute. This is implemented as a new AST node ast.TypeAlias.

    New syntax (class X[T]: ..., def func[T](): ...) is added for defining generic functions and classes. This is implemented as a new type_params attribute on the AST nodes for classes and functions. This node holds instances of the new AST classes ast.TypeVar, ast.ParamSpec, and ast.TypeVarTuple.

    typing.TypeVar, typing.ParamSpec, typing.ParamSpecArgs, typing.ParamSpecKwargs, typing.TypeVarTuple, and typing.Generic are now implemented in C rather than Python.

    There are new bytecode instructions LOAD_LOCALS, LOAD_CLASSDICT_OR_GLOBAL, and LOAD_CLASSDICT_OR_DEREF to support correct resolution of names in class namespaces.

    Patch by Eric Traut, Larry Hastings, and Jelle Zijlstra.

  • gh-103801: Adds three minor linting fixes to the wasm module caught that were caught by ruff.

  • gh-103793: Optimized asyncio Task creation by deferring expensive string formatting (task name generation) from Task creation to the first time get_name is called. This makes asyncio benchmarks up to 5% faster.

  • gh-102310: Change the error range for invalid bytes literals.

  • gh-103590: Do not wrap a single exception raised from a try-except* construct in an ExceptionGroup.

  • gh-103650: Change the perf map format to remove the ‘0x’ prefix from the addresses

  • gh-102856: Implement the required C tokenizer changes for PEP 701. Patch by Pablo Galindo Salgado, Lysandros Nikolaou, Batuhan Taskaya, Marta Gómez Macías and sunmy2019.

  • gh-100530: Clarify the error message raised when the called part of a class pattern isn’t actually a class.

  • gh-101517: Fix bug in line numbers of instructions emitted for except*.

  • gh-103492: Clarify SyntaxWarning with literal is comparison by specifying which literal is problematic, since comparisons using is with e.g. None and bool literals are idiomatic.

  • gh-87729: Add LOAD_SUPER_ATTR (and a specialization for super().method()) to speed up super().method() and super().attr. This makes super().method() roughly 2.3x faster and brings it within 20% of the performance of a simple method call. Patch by Vladimir Matveev and Carl Meyer.

  • gh-103488: Change the internal offset distinguishing yield and return target addresses, so that the instruction pointer is correct for exception handling and other stack unwinding.

  • gh-82012: The bitwise inversion operator (~) on bool is deprecated. It returns the bitwise inversion of the underlying int representation such that bool(~True) == True, which can be confusing. Use not for logical negation of bools. In the rare case that you really need the bitwise inversion of the underlying int, convert to int explicitly ~int(x).

  • gh-77757: Exceptions raised in a typeobject’s __set_name__ method are no longer wrapped by a RuntimeError. Context information is added to the exception as a PEP 678 note.

  • gh-103333: AttributeError now retains the name attribute when pickled and unpickled.

  • gh-103242: Migrate set_ecdh_curve() method not to use deprecated OpenSSL APIs. Patch by Donghee Na.

  • gh-103323: We’ve replaced our use of _PyRuntime.tstate_current with a thread-local variable. This is a fairly low-level implementation detail, and there should be no change in behavior.

  • gh-84436: The implementation of PEP-683 which adds Immortal Objects by using a fixed reference count that skips reference counting to make objects truly immutable.

  • gh-102700: Allow built-in modules to be submodules. This allows submodules to be statically linked into a CPython binary.

  • gh-103082: Implement PEP 669 Low Impact Monitoring for CPython.

  • gh-88691: Reduce the number of inline CACHE entries for CALL.

  • gh-102500: Make the buffer protocol accessible in Python code using the new __buffer__ and __release_buffer__ magic methods. See PEP 688 for details. Patch by Jelle Zijlstra.

  • gh-97933: PEP 709: inline list, dict and set comprehensions to improve performance and reduce bytecode size.

  • gh-99184: Bypass instance attribute access of __name__ in repr of weakref.ref.

  • gh-98003: Complex function calls are now faster and consume no C stack space.

  • bpo-39610: len() for 0-dimensional memoryview` objects (such as memoryview(ctypes.c_uint8(42))) now raises a TypeError. Previously this returned 1, which was not consistent with mem_0d[0] raising an IndexError`.

  • bpo-31821: Fix pause_reading() to work when called from connection_made() in asyncio.

Library

  • gh-104600: functools.update_wrapper() now sets the __type_params__ attribute (added by PEP 695).

  • gh-104340: When an asyncio pipe protocol loses its connection due to an error, and the caller doesn’t await wait_closed() on the corresponding StreamWriter, don’t log a warning about an exception that was never retrieved. After all, according to the StreamWriter.close() docs, the wait_closed() call is optional (“not mandatory”).

  • gh-104555: Fix issue where an issubclass() check comparing a class X against a runtime-checkable protocol Y with non-callable members would not cause TypeError to be raised if an isinstance() call had previously been made comparing an instance of X to Y. This issue was present in edge cases on Python 3.11, but became more prominent in 3.12 due to some unrelated changes that were made to runtime-checkable protocols. Patch by Alex Waygood.

  • gh-104372: Refactored the _posixsubprocess internals to avoid Python C API usage between fork and exec when marking pass_fds= file descriptors inheritable.

  • gh-104484: Added case_sensitive argument to pathlib.PurePath.match()

  • gh-75367: Fix data descriptor detection in inspect.getattr_static().

  • gh-104536: Fix a race condition in the internal multiprocessing.process cleanup logic that could manifest as an unintended AttributeError when calling process.close().

  • gh-103857: Update datetime deprecations’ stracktrace to point to the calling line

  • gh-101520: Move the core functionality of the tracemalloc module in the Python/ folder, leaving just the module wrapper in Modules/.

  • gh-104392: Remove undocumented and unused _paramspec_tvars attribute from some classes in typing.

  • gh-102613: Fix issue where pathlib.Path.glob() raised RecursionError when walking deep directory trees.

  • gh-103000: Improve performance of dataclasses.asdict() for the common case where dict_factory is dict. Patch by David C Ellis.

  • gh-104301: Allow leading whitespace in disambiguated statements in pdb.

  • gh-104139: Teach urllib.parse.unsplit() to retain the "//" when assembling itms-services://?action=generate-bugs style Apple Platform Deployment URLs.

  • gh-104307: socket.getnameinfo() now releases the GIL while contacting the DNS server

  • gh-104310: Users may now use importlib.util.allowing_all_extensions() (a context manager) to temporarily disable the strict compatibility checks for importing extension modules in subinterpreters.

  • gh-87695: Fix issue where pathlib.Path.glob() raised OSError when it encountered a symlink to an overly long path.

  • gh-104265: Prevent possible crash by disallowing instantiation of the _csv.Reader and _csv.Writer types. The regression was introduced in 3.10.0a4 with PR 23224 (bpo-14935). Patch by Radislav Chugunov.

  • gh-102613: Improve performance of pathlib.Path.glob() when expanding recursive wildcards (”**”) by merging adjacent wildcards and de-duplicating results only when necessary.

  • gh-65772: Remove unneeded comments and code in turtle.py.

  • gh-90208: Fixed issue where pathlib.Path.glob() returned incomplete results when it encountered a PermissionError. This method now suppresses all OSError exceptions, except those raised from calling is_dir() on the top-level path.

  • gh-104144: Optimize asyncio.TaskGroup when using asyncio.eager_task_factory(). Skip scheduling a done callback if a TaskGroup task completes eagerly.

  • gh-104144: Optimize asyncio.gather() when using asyncio.eager_task_factory() to complete eagerly if all fututres completed eagerly. Avoid scheduling done callbacks for futures that complete eagerly.

  • gh-104114: Fix issue where pathlib.Path.glob() returns paths using the case of non-wildcard segments for corresponding path segments, rather than the real filesystem case.

  • gh-104104: Improve performance of pathlib.Path.glob() by using re.IGNORECASE to implement case-insensitive matching.

  • gh-104102: Improve performance of pathlib.Path.glob() when evaluating patterns that contain '../' segments.

  • gh-103822: Update the return type of weekday to the newly added Day attribute

  • gh-103629: Update the repr of typing.Unpack according to PEP 692.

  • gh-103963: Make dis display the names of the args for CALL_INTRINSIC_*.

  • gh-104035: Do not ignore user-defined __getstate__ and __setstate__ methods for slotted frozen dataclasses.

  • gh-103987: In mmap, fix several bugs that could lead to access to memory-mapped files after they have been invalidated.

  • gh-103977: Improve import time of platform module.

  • gh-88773: Added turtle.teleport() to the turtle module to move a turtle to a new point without tracing a line, visible or invisible. Patch by Liam Gersten.

  • gh-103935: Use io.open_code() for files to be executed instead of raw open()

  • gh-68968: Fixed garbled output of assertEqual() when an input lacks final newline.

  • gh-100370: Fix potential OverflowError in sqlite3.Connection.blobopen() for 32-bit builds. Patch by Erlend E. Aasland.

  • gh-102628: Substitute CTRL-D with CTRL-Z in sqlite3 CLI banner when running on Windows.

  • gh-103636: Module-level attributes January and February are deprecated from calendar.

  • gh-103583: Isolate _multibytecodec and codecs extension modules. Patches by Erlend E. Aasland.

  • gh-103848: Add checks to ensure that [ bracketed ] hosts found by urllib.parse.urlsplit() are of IPv6 or IPvFuture format.

  • gh-103872: Update the bundled copy of pip to version 23.1.2.

  • gh-99944: Make dis display the value of oparg of KW_NAMES.

  • gh-74940: The C.UTF-8 locale is no longer converted to en_US.UTF-8, enabling the use of UTF-8 encoding on systems which have no locales installed.

  • gh-103861: Fix zipfile.Zipfile creating invalid zip files when force_zip64 was used to add files to them. Patch by Carey Metcalfe.

  • gh-103857: Deprecated datetime.datetime.utcnow() and datetime.datetime.utcfromtimestamp(). (Patch by Paul Ganssle)

  • gh-103839: Avoid compilation error due to tommath.h not being found when building Tkinter against Tcl 8.7 built with bundled libtommath.

  • gh-103791: contextlib.suppress now supports suppressing exceptions raised as part of an ExceptionGroup. If other exceptions exist on the group, they are re-raised in a group that does not contain the suppressed exceptions.

  • gh-90750: Use datetime.datetime.fromisocalendar() in the implementation of datetime.datetime.strptime(), which should now accept only valid ISO dates. (Patch by Paul Ganssle)

  • gh-103685: Prepare tkinter.Menu.index() for Tk 8.7 so that it does not raise TclError: expected integer but got "" when it should return None.

  • gh-81403: urllib.request.CacheFTPHandler no longer raises URLError if a cached FTP instance is reused. ftplib’s endtransfer method calls voidresp to drain the connection to handle FTP instance reuse properly.

  • gh-103699: Add __orig_bases__ to non-generic TypedDicts, call-based TypedDicts, and call-based NamedTuples. Other TypedDicts and NamedTuples already had the attribute.

  • gh-103693: Add convenience variable feature to pdb

  • gh-92248: Deprecate type, choices, and metavar parameters of argparse.BooleanOptionalAction.

  • gh-89415: Add socket constants for source-specific multicast. Patch by Reese Hyde.

  • gh-103673: socketserver gains ForkingUnixStreamServer and ForkingUnixDatagramServer classes. Patch by Jay Berry.

  • gh-103636: Added Enum for months and days in the calendar module.

  • gh-84976: Create a new Lib/_pydatetime.py file that defines the Python version of the datetime module, and make datetime import the contents of the new library only if the C implementation is missing. Currently, the full Python implementation is defined and then deleted if the C implementation is not available, slowing down import datetime unnecessarily.

  • gh-103596: Attributes/methods are no longer shadowed by same-named enum members, although they may be shadowed by enum.property’s.

  • gh-103584: Updated importlib.metadata with changes from importlib_metadata 5.2 through 6.5.0, including: Support installed-files.txt for Distribution.files when present. PackageMetadata now stipulates an additional get method allowing for easy querying of metadata keys that may not be present. packages_distributions now honors packages and modules with Python modules that not .py sources (e.g. .pyc, .so). Expand protocol for PackageMetadata.get_all to match the upstream implementation of email.message.Message.get_all in python/typeshed#9620. Deprecated use of Distribution without defining abstract methods. Deprecated expectation that PackageMetadata.__getitem__ will return None for missing keys. In the future, it will raise a KeyError.

  • gh-103578: Fixed a bug where pdb crashes when reading source file with different encoding by replacing io.open() with io.open_code(). The new method would also call into the hook set by PyFile_SetOpenCodeHook().

  • gh-103556: Now creating inspect.Signature objects with positional-only parameter with a default followed by a positional-or-keyword parameter without one is impossible.

  • gh-103559: Update the bundled copy of pip to version 23.1.1.

  • gh-103548: Improve performance of pathlib.Path.absolute() and cwd() by joining paths only when necessary. Also improve performance of pathlib.PurePath.is_absolute() on Posix by skipping path parsing and normalization.

  • gh-103538: Remove _tkinter module code guarded by definition of the TK_AQUA macro which was only needed for Tk 8.4.7 or earlier and was never actually defined by any build system or documented for manual use.

  • gh-103533: Update cProfile to use PEP 669 API

  • gh-103525: Fix misleading exception message when mixed str and bytes arguments are supplied to pathlib.PurePath and Path.

  • gh-103489: Add getconfig() and setconfig() to Connection to make configuration changes to a database connection. Patch by Erlend E. Aasland.

  • gh-103365: Set default Flag boundary to STRICT and fix bitwise operations.

  • gh-103472: Avoid a potential ResourceWarning in http.client.HTTPConnection by closing the proxy / tunnel’s CONNECT response explicitly.

  • gh-103462: Fixed an issue with using writelines() in asyncio to send very large payloads that exceed the amount of data that can be written in one call to socket.socket.send() or socket.socket.sendmsg(), resulting in the remaining buffer being left unwritten.

  • gh-103449: Fix a bug in doc string generation in dataclasses.dataclass().

  • gh-103092: Isolate _collections (apply PEP 687). Patch by Erlend E. Aasland.

  • gh-103357: Added support for logging.Formatter defaults parameter to logging.config.dictConfig() and logging.config.fileConfig(). Patch by Bar Harel.

  • gh-103092: Adapt the winreg extension module to PEP 687.

  • gh-74690: The performance of isinstance() checks against runtime-checkable protocols has been considerably improved for protocols that only have a few members. To achieve this improvement, several internal implementation details of the typing module have been refactored, including typing._ProtocolMeta.__instancecheck__, typing._is_callable_members_only, and typing._get_protocol_attrs. Patches by Alex Waygood.

  • gh-74690: The members of a runtime-checkable protocol are now considered “frozen” at runtime as soon as the class has been created. See “What’s new in Python 3.12” for more details.

  • gh-103256: Fixed a bug that caused hmac to raise an exception when the requested hash algorithm was not available in OpenSSL despite being available separately as part of hashlib itself. It now falls back properly to the built-in. This could happen when, for example, your OpenSSL does not include SHA3 support and you want to compute hmac.digest(b'K', b'M', 'sha3_256').

  • gh-102778: Support sys.last_exc in idlelib.

  • gh-103285: Improve performance of ast.get_source_segment().

  • gh-103225: Fix a bug in pdb when displaying line numbers of module-level source code.

  • gh-103092: Adapt the msvcrt extension module to PEP 687.

  • gh-103092: Adapt the winsound extension module to PEP 687.

  • gh-93910: Remove deprecation of enum memmber.member access.

  • gh-102978: Fixes unittest.mock.patch() not enforcing function signatures for methods decorated with @classmethod or @staticmethod when patch is called with autospec=True.

  • gh-103092: Isolate _socket (apply PEP 687). Patch by Erlend E. Aasland.

  • gh-100479: Add pathlib.PurePath.with_segments(), which creates a path object from arguments. This method is called whenever a derivative path is created, such as from pathlib.PurePath.parent. Subclasses may override this method to share information between path objects.

  • gh-103220: Fix issue where os.path.join() added a slash when joining onto an incomplete UNC drive with a trailing slash on Windows.

  • gh-103204: Fixes http.server accepting HTTP requests with HTTP version numbers preceded by ‘+’, or ‘-’, or with digit-separating ‘_’ characters. The length of the version numbers is also constrained.

  • gh-75586: Fix various Windows-specific issues with shutil.which.

  • gh-103193: Improve performance of inspect.getattr_static(). Patch by Alex Waygood.

  • gh-103176: sys._current_exceptions() now returns a mapping from thread-id to an exception instance, rather than to a (typ, exc, tb) tuple.

  • gh-103143: Polish the help messages and docstrings of pdb.

  • gh-103015: Add entrypoint keyword-only parameter to sqlite3.Connection.load_extension(), for overriding the SQLite extension entry point. Patch by Erlend E. Aasland.

  • gh-103000: Improve performance of dataclasses.astuple() and dataclasses.asdict() in cases where the contents are common Python types.

  • gh-102953: The extraction methods in tarfile, and shutil.unpack_archive(), have a new a filter argument that allows limiting tar features than may be surprising or dangerous, such as creating files outside the destination directory. See Extraction filters for details.

  • gh-97696: Implemented an eager task factory in asyncio. When used as a task factory on an event loop, it performs eager execution of coroutines. Coroutines that are able to complete synchronously (e.g. return or raise without blocking) are returned immediately as a finished task, and the task is never scheduled to the event loop. If the coroutine blocks, the (pending) task is scheduled and returned.

  • gh-81079: Add case_sensitive keyword-only argument to pathlib.Path.glob() and rglob().

  • gh-101819: Isolate the io extension module by applying PEP 687. Patch by Kumar Aditya, Victor Stinner, and Erlend E. Aasland.

  • gh-91896: Deprecate collections.abc.ByteString

  • gh-101362: Speed up pathlib.Path construction by omitting the path anchor from the internal list of path parts.

  • gh-102114: Functions in the dis module that accept a source code string as argument now print a more concise traceback when the string contains a syntax or indentation error.

  • gh-62432: The unittest runner will now exit with status code 5 if no tests were run. It is common for test runner misconfiguration to fail to find any tests, this should be an error.

  • gh-78079: Fix incorrect normalization of UNC device path roots, and partial UNC share path roots, in pathlib.PurePath. Pathlib no longer appends a trailing slash to such paths.

  • gh-85984: Add tty.cfmakeraw() and tty.cfmakecbreak() to tty and modernize, the behavior of tty.setraw() and tty.setcbreak() to use POSIX.1-2017 Chapter 11 “General Terminal Interface” flag masks by default.

  • gh-101688: Implement types.get_original_bases() to provide further introspection for types.

  • gh-101640: argparse.ArgumentParser now catches errors when writing messages, such as when sys.stderr is None. Patch by Oleg Iarygin.

  • gh-83861: Fix datetime.astimezone method return value when invoked on a naive datetime instance that represents local time falling in a timezone transition gap. PEP 495 requires that instances with fold=1 produce earlier times than those with fold=0 in this case.

  • gh-89550: Decrease execution time of some gzip file writes by 15% by adding more appropriate buffering.

  • gh-95299: Remove the bundled setuptools wheel from ensurepip, and stop installing setuptools in environments created by venv.

  • gh-99353: Respect the http.client.HTTPConnection .debuglevel flag in urllib.request.AbstractHTTPHandler when its constructor parameter debuglevel is not set. And do the same for *HTTPS*.

  • gh-98040: Remove the long-deprecated imp module.

  • gh-97850: Deprecate pkgutil.find_loader() and pkgutil.get_loader() in favor of importlib.util.find_spec().

  • gh-94473: Flatten arguments in tkinter.Canvas.coords(). It now accepts not only x1, y1, x2, y2, ... and [x1, y1, x2, y2, ...], but also (x1, y1), (x2, y2), ... and [(x1, y1), (x2, y2), ...].

  • gh-98040: Remove more deprecated importlib APIs: find_loader(), find_module(), importlib.abc.Finder, pkgutil.ImpImporter, pkgutil.ImpLoader.

  • gh-96522: Fix potential deadlock in pty.spawn()

  • gh-96534: Support divert(4) added in FreeBSD 14.

  • gh-87474: Fix potential file descriptor leaks in subprocess.Popen.

  • gh-94906: Support multiple steps in math.nextafter(). Patch by Shantanu Jain and Matthias Gorgens.

  • gh-51574: Make tempfile.mkdtemp() return absolute paths when its dir parameter is relative.

  • gh-94518: Convert private _posixsubprocess.fork_exec() to use Argument Clinic.

  • gh-92184: When creating zip files using zipfile, os.altsep, if not None, will always be treated as a path separator even when it is not /. Patch by Carey Metcalfe.

  • bpo-46797: Deprecation warnings are now emitted for ast.Num, ast.Bytes, ast.Str, ast.NameConstant and ast.Ellipsis. These have been documented as deprecated since Python 3.8, and will be removed in Python 3.14.

  • bpo-44844: Enables webbrowser to detect and launch Microsoft Edge browser.

  • bpo-45606: Fixed the bug in pathlib.Path.glob() – previously a dangling symlink would not be found by this method when the pattern is an exact match, but would be found when the pattern contains a wildcard or the recursive wildcard (**). With this change, a dangling symlink will be found in both cases.

  • bpo-23041: Add QUOTE_STRINGS and QUOTE_NOTNULL to the suite of csv module quoting styles.

  • bpo-24964: Added http.client.HTTPConnection.get_proxy_response_headers() that provides access to the HTTP headers on a proxy server response to the CONNECT request.

  • bpo-17258: multiprocessing now supports stronger HMAC algorithms for inter-process connection authentication rather than only HMAC-MD5.

  • bpo-39744: Make asyncio.subprocess.Process.communicate() close the subprocess’s stdin even when called with input=None.

  • bpo-22708: http.client CONNECT method tunnel improvements: Use HTTP 1.1 protocol; send a matching Host: header with CONNECT, if one is not provided; convert IDN domain names to Punycode. Patch by Michael Handler.

Documentation

  • gh-67056: Document that the effect of registering or unregistering an atexit cleanup function from within a registered cleanup function is undefined.

  • gh-103629: Mention the new way of typing **kwargs with Unpack and TypedDict introduced in PEP 692.

  • gh-48241: Clarifying documentation about the url parameter to urllib.request.urlopen and urllib.request.Request needing to be encoded properly.

  • gh-86094: Add support for Unicode Path Extra Field in ZipFile. Patch by Yeojin Kim and Andrea Giudiceandrea

  • gh-99202: Fix extension type from documentation for compiling in C++20 mode

Tests

  • gh-104494: Update test_pack_configure_in and test_place_configure_in for changes to error message formatting in Tk 8.7.

  • gh-104461: Run test_configure_screen on X11 only, since the DISPLAY environment variable and -screen option for toplevels are not useful on Tk for Win32 or Aqua.

  • gh-86275: Added property-based tests to the zoneinfo tests, along with stubs for the hypothesis interface. (Patch by Paul Ganssle)

  • gh-103329: Regression tests for the behaviour of unittest.mock.PropertyMock were added.

  • gh-102795: fix use of poll in test_epoll’s test_control_and_wait

  • gh-75729: Fix the os.spawn* tests failing on Windows when the working directory or interpreter path contains spaces.

Build

  • gh-101282: BOLT optimization is now applied to the libpython shared library if building a shared library. BOLT instrumentation and application settings can now be influenced via the BOLT_INSTRUMENT_FLAGS and BOLT_APPLY_FLAGS configure variables.

  • gh-99017: PYTHON_FOR_REGEN now require Python 3.10 or newer.

  • gh-104490: Define .PHONY / virtual make targets consistently and properly.

  • gh-104106: Add gcc fallback of mkfifoat/mknodat for macOS. Patch by Donghee Na.

  • gh-103532: The TKINTER_PROTECT_LOADTK macro is no longer defined or used in the _tkinter module. It was previously only defined when building against Tk 8.4.13 and older, but Tk older than 8.5.12 has been unsupported since gh-91152.

  • gh-99069: Extended workaround defining static_assert when missing from the libc headers to all clang and gcc builds. In particular, this fixes building on macOS <= 10.10.

  • gh-100220: Changed the default value of the SHELL Makefile variable from /bin/sh to /bin/sh -e to ensure that complex recipes correctly fail after an error. Previously, make install could fail to install some files and yet return a successful result.

  • gh-90656: Add platform triplets for 64-bit LoongArch:

    • loongarch64-linux-gnusf

    • loongarch64-linux-gnuf32

    • loongarch64-linux-gnu

    Patch by Zhang Na.

Windows

  • gh-104623: Update Windows installer to use SQLite 3.42.0.

  • gh-82814: Fix a potential [Errno 13] Permission denied when using shutil.copystat() within Windows Subsystem for Linux (WSL) on a mounted filesystem by adding errno.EACCES to the list of ignored errors within the internal implementation.

  • gh-103088: Fix virtual environment activate script having incorrect line endings for Cygwin.

  • gh-103088: Fixes venvs not working in bash on Windows across different disks

  • gh-102997: Update Windows installer to use SQLite 3.41.2.

  • gh-88013: Fixed a bug where TypeError was raised when calling ntpath.realpath() with a bytes parameter in some cases.

macOS

  • gh-99834: Update macOS installer to Tcl/Tk 8.6.13.

  • gh-104623: Update macOS installer to SQLite 3.42.0.

  • gh-103545: Add os.PRIO_DARWIN_THREAD, os.PRIO_DARWIN_PROCESS, os.PRIO_DARWIN_BG and os.PRIO_DARWIN_NONUI. These can be used with os.setpriority to run the process at a lower priority and make use of the efficiency cores on Apple Silicon systems.

  • gh-104180: Support reading SOCKS proxy configuration from macOS System Configuration. Patch by Sam Schott.

  • gh-60436: update curses textbox to additionally handle backspace using the curses.ascii.DEL key press.

  • gh-102997: Update macOS installer to SQLite 3.41.2.

IDLE

  • gh-104499: Fix completions for Tk Aqua 8.7 (currently blank).

  • gh-104496: About prints both tcl and tk versions if different (expected someday).

  • gh-88496: Fix IDLE test hang on macOS.

Tools/Demos

  • gh-104389: Argument Clinic C converters now accept the unused keyword, for wrapping a parameter with Py_UNUSED. Patch by Erlend E. Aasland.

C API

Python 3.12.0 alpha 7

Release date: 2023-04-04

Core and Builtins

  • gh-102192: Deprecated _PyErr_ChainExceptions in favour of _PyErr_ChainExceptions1.

  • gh-89987: Reduce the number of inline CACHE entries for BINARY_SUBSCR.

  • gh-102859: Removed JUMP_IF_FALSE_OR_POP and JUMP_IF_TRUE_OR_POP instructions.

  • gh-101975: Fixed stacktop value on tracing entries to avoid corruption on garbage collection.

  • gh-102778: Add sys.last_exc and deprecate sys.last_type, sys.last_value and sys.last_traceback, which hold the same information in its legacy form.

  • gh-100982: Replace all occurrences of COMPARE_AND_BRANCH with COMPARE_OP.

  • gh-102701: Fix overflow when creating very large dict.

  • gh-102755: Add PyErr_DisplayException() which takes just an exception instance, to replace the legacy PyErr_Display() which takes the (typ, exc, tb) triplet.

  • gh-102594: Add note to exception raised in PyErr_SetObject when normalization fails.

  • gh-90997: Shrink the number of inline CACHE entries used by LOAD_GLOBAL.

  • gh-102491: Improve import time of platform by removing IronPython version parsing. The IronPython version parsing was not functional (see https://github.com/IronLanguages/ironpython3/issues/1667).

  • gh-101291: Rearrage bits in first field (after header) of PyLongObject. * Bits 0 and 1: 1 - sign. I.e. 0 for positive numbers, 1 for zero and 2 for negative numbers. * Bit 2 reserved (probably for the immortal bit) * Bits 3+ the unsigned size.

    This makes a few operations slightly more efficient, and will enable a more compact and faster 2s-complement representation of most ints in future.

  • gh-102397: Fix segfault from race condition in signal handling during garbage collection. Patch by Kumar Aditya.

  • gh-102406: codecs encoding/decoding errors now get the context information (which operation and which codecs) attached as PEP 678 notes instead of through chaining a new instance of the exception.

  • gh-102281: Fix potential nullptr dereference and use of uninitialized memory in fileutils. Patch by Max Bachmann.

  • gh-102300: Reuse operands with refcount of 1 in float specializations of BINARY_OP.

  • gh-102213: Fix performance loss when accessing an object’s attributes with __getattr__ defined.

  • gh-102255: Improve build support for the Xbox. Patch by Max Bachmann.

  • gh-102027: Fix SSE2 and SSE3 detection in _blake2 internal module. Patch by Max Bachmann.

  • gh-101865: Deprecate co_lnotab in code objects, schedule it for removal in Python 3.14

  • bpo-1635741: Adapt _pickle to PEP 687. Patch by Mohamed Koubaa and Erlend Aasland.

Library

Documentation

Tests

  • gh-102980: Improve test coverage on pdb.

  • gh-102537: Adjust the error handling strategy in test_zoneinfo.TzPathTest.python_tzpath_context. Patch by Paul Ganssle.

  • gh-101377: Improved test_locale_calendar_formatweekday of calendar.

Build

  • gh-102973: Add a dev container (along with accompanying Dockerfile) for development purposes.

  • gh-102711: Fix -Wstrict-prototypes compiler warnings.

Windows

  • gh-102690: Update webbrowser to fall back to Microsoft Edge instead of Internet Explorer.

  • gh-99726: Improves correctness of stat results for Windows, and uses faster API when available

Tools/Demos

C API

  • gh-102013: Add a new (unstable) C-API function for iterating over GC’able objects using a callback: PyUnstable_VisitObjects.

Python 3.12.0 alpha 6

Release date: 2023-03-07

Security

  • gh-99108: Replace builtin hashlib implementations of MD5 and SHA1 with verified ones from the HACL* project.

  • gh-101727: Updated the OpenSSL version used in Windows and macOS binary release builds to 1.1.1t to address CVE-2023-0286, CVE-2022-4303, and CVE-2022-4303 per the OpenSSL 2023-02-07 security advisory.

  • gh-99108: Replace the builtin hashlib implementations of SHA2-384 and SHA2-512 originally from LibTomCrypt with formally verified, side-channel resistant code from the HACL* project. The builtins remain a fallback only used when OpenSSL does not provide them.

  • gh-101283: subprocess.Popen now uses a safer approach to find cmd.exe when launching with shell=True. Patch by Eryk Sun, based on a patch by Oleg Iarygin.

Core and Builtins

  • gh-102493: Fix regression in semantics of normalisation in PyErr_SetObject.

  • gh-102416: Do not memoize incorrectly automatically generated loop rules in the parser. Patch by Pablo Galindo.

  • gh-102356: Fix a bug that caused a crash when deallocating deeply nested filter objects. Patch by Marta Gómez Macías.

  • gh-102336: Cleanup Windows 7 specific special handling. Patch by Max Bachmann.

  • gh-102250: Fixed a segfault occurring when the interpreter calls a __bool__ method that raises.

  • gh-102126: Fix deadlock at shutdown when clearing thread states if any finalizer tries to acquire the runtime head lock. Patch by Kumar Aditya.

  • gh-102027: Use GetCurrentProcessId on Windows when getpid is unavailable. Patch by Max Bachmann.

  • gh-102056: Fix error handling bugs in interpreter’s exception printing code, which could cause a crash on infinite recursion.

  • gh-100982: Restrict the scope of the FOR_ITER_RANGE instruction to the scope of the original FOR_ITER instruction, to allow instrumentation.

  • gh-101967: Fix possible segfault in positional_only_passed_as_keyword function, when new list created.

  • gh-101952: Fix possible segfault in BUILD_SET opcode, when new set created.

  • gh-74895: socket.getaddrinfo no longer raises OverflowError for int port values outside of the C long range. Out of range values are left up to the underlying string based C library API to report. A socket.gaierror SAI_SERVICE may occur instead, or no error at all as not all platform C libraries generate an error.

  • gh-101799: Add CALL_INTRINSIC_2 and use it instead of PREP_RERAISE_STAR.

  • gh-101857: Fix xattr support detection on Linux systems by widening the check to linux, not just glibc. This fixes support for musl.

  • gh-84783: Make the slice object hashable. Patch by Will Bradshaw and Furkan Onder.

  • gh-87849: Change the SEND instruction to leave the receiver on the stack. This allows the specialized form of SEND to skip the chain of C calls and jump directly to the RESUME in the generator or coroutine.

  • gh-101765: Fix SystemError / segmentation fault in iter __reduce__ when internal access of builtins.__dict__ keys mutates the iter object.

  • gh-101430: Update tracemalloc to handle presize of object properly. Patch by Donghee Na.

  • gh-101696: Invalidate type version tag in _PyStaticType_Dealloc for static types, avoiding bug where a false cache hit could crash the interpreter. Patch by Kumar Aditya.

  • gh-101632: Adds a new RETURN_CONST instruction.

  • gh-100719: Remove gi_code field from generator (and coroutine and async generator) objects as it is redundant. The frame already includes a reference to the code object.

  • gh-98627: When an interpreter is configured to check (and only then), importing an extension module will now fail when the extension does not support multiple interpreters (i.e. doesn’t implement PEP 489 multi-phase init). This does not apply to the main interpreter, nor to subinterpreters created with Py_NewInterpreter().

Library

Documentation

Tests

  • gh-102019: Fix deadlock on shutdown if test_current_{exception,frames} fails. Patch by Jacob Bower.

  • gh-85984: Utilize new “winsize” functions from termios in pty tests.

  • gh-89792: test_tools now copies up to 10x less source data to a temporary directory during the freeze test by ignoring git metadata and other artifacts. It also limits its python build parallelism based on os.cpu_count instead of hard coding it as 8 cores.

Build

  • gh-99942: On Android, in a static build, python-config in embed mode no longer incorrectly reports a library to link to.

  • gh-99942: On Android, python.pc now correctly reports the library to link to, the same as python-config.sh.

  • gh-100221: Fix creating install directories in make sharedinstall if they exist outside DESTDIR already.

  • gh-96821: Explicitly mark C extension modules that need defined signed integer overflow, and add a configure option --with-strict-overflow. Patch by Matthias Görgens and Shantanu Jain.

Windows

  • gh-102344: Implement winreg.QueryValue using QueryValueEx and winreg.SetValue using SetValueEx. Patch by Max Bachmann.

  • gh-101881: Handle read and write operations on non-blocking pipes properly on Windows.

  • gh-101881: Add support for the os.get_blocking() and os.set_blocking() functions on Windows.

  • gh-101849: Ensures installer will correctly upgrade existing py.exe launcher installs.

  • gh-101763: Updates copy of libffi bundled with Windows installs to 3.4.4.

  • gh-101759: Update Windows installer to SQLite 3.40.1.

  • gh-101614: Correctly handle extensions built against debug binaries that reference python3_d.dll.

  • gh-101196: The functions os.path.isdir, os.path.isfile, os.path.islink and os.path.exists are now 13% to 28% faster on Windows, by making fewer Win32 API calls.

macOS

  • gh-101759: Update macOS installer to SQLite 3.40.1.

C API

  • gh-101907: Removes use of non-standard C++ extension in public header files.

  • gh-99293: Document that the Py_TPFLAGS_VALID_VERSION_TAG is an internal feature, should not be used, and will be removed.

  • gh-101578: Add PyErr_GetRaisedException() and PyErr_SetRaisedException() for saving and restoring the current exception. These functions return and accept a single exception object, rather than the triple arguments of the now-deprecated PyErr_Fetch() and PyErr_Restore(). This is less error prone and a bit more efficient.

    Add PyException_GetArgs() and PyException_SetArgs() as convenience functions for retrieving and modifying the args passed to the exception’s constructor.

  • gh-91744: Introduced the Unstable C API tier, marking APi that is allowed to change in minor releases without a deprecation period. See PEP 689 for details.

Python 3.12.0 alpha 5

Release date: 2023-02-07

Security

  • gh-99108: Replace the builtin hashlib implementations of SHA2-224 and SHA2-256 originally from LibTomCrypt with formally verified, side-channel resistant code from the HACL* project. The builtins remain a fallback only used when OpenSSL does not provide them.

Core and Builtins

  • gh-92173: Fix the defs and kwdefs arguments to PyEval_EvalCodeEx() and a reference leak in that function.

  • gh-59956: The GILState API is now partially compatible with subinterpreters. Previously, PyThreadState_GET() and PyGILState_GetThisThreadState() would get out of sync, causing inconsistent behavior and crashes.

  • gh-101400: Fix wrong lineno in exception message on continue or break which are not in a loop. Patch by Donghee Na.

  • gh-101372: Fix is_normalized() to properly handle the UCD 3.2.0 cases. Patch by Donghee Na.

  • gh-101266: Fix sys.getsizeof() reporting for int subclasses.

  • gh-101291: Refactor the PyLongObject struct into a normal Python object header and a PyLongValue struct.

  • gh-101046: Fix a possible memory leak in the parser when raising MemoryError. Patch by Pablo Galindo

  • gh-101037: Fix potential memory underallocation issue for instances of int subclasses with value zero.

  • gh-100762: Record the (virtual) exception block depth in the oparg of YIELD_VALUE. Use this to avoid the expensive throw() when closing generators (and coroutines) that can be closed trivially.

  • gh-100982: Adds a new COMPARE_AND_BRANCH instruction. This is a bit more efficient when performing a comparison immediately followed by a branch, and restores the design intent of PEP 659 that specializations are local to a single instruction.

  • gh-100942: Fixed segfault in property.getter/setter/deleter that occurred when a property subclass overrode the __new__ method to return a non-property instance.

  • gh-100923: Remove the mask cache entry for the COMPARE_OP instruction and embed the mask into the oparg.

  • gh-100892: Fix race while iterating over thread states in clearing threading.local. Patch by Kumar Aditya.

  • gh-91351: Fix a case where re-entrant imports could corrupt the import deadlock detection code and cause a KeyError to be raised out of importlib/_bootstrap. In addition to the straightforward cases, this could also happen when garbage collection leads to a warning being emitted – as happens when it collects an open socket or file)

  • gh-100726: Optimize construction of range object for medium size integers.

  • gh-100712: Added option to build cpython with specialization disabled, by setting ENABLE_SPECIALIZATION=False in opcode, followed by make regen-all.

  • bpo-32780: Inter-field padding is now inserted into the PEP3118 format strings obtained from ctypes.Structure objects, reflecting their true representation in memory.

Library

  • gh-101541: [Enum] - fix psuedo-flag creation

  • gh-101570: Upgrade pip wheel bundled with ensurepip (pip 23.0)

  • gh-101323: Fix a bug where errors where not thrown by zlib._ZlibDecompressor if encountered during decompressing.

  • gh-101317: Add ssl_shutdown_timeout parameter for asyncio.StreamWriter.start_tls().

  • gh-101326: Fix regression when passing None as second or third argument to FutureIter.throw.

  • gh-92123: Adapt the _elementtree extension module to multi-phase init (PEP 489). Patches by Erlend E. Aasland.

  • gh-100795: Avoid potential unexpected freeaddrinfo call (double free) in socket when when a libc getaddrinfo() implementation leaves garbage in an output pointer when returning an error. Original patch by Sergey G. Brester.

  • gh-101143: Remove unused references to TimerHandle in asyncio.base_events.BaseEventLoop._add_callback.

  • gh-101144: Make zipfile.Path.open() and zipfile.Path.read_text() also accept encoding as a positional argument. This was the behavior in Python 3.9 and earlier. 3.10 introduced a regression where supplying it as a positional argument would lead to a TypeError.

  • gh-94518: Group-related variables of _posixsubprocess module are renamed to stress that supplimentary group affinity is added to a fork, not replace the inherited ones. Patch by Oleg Iarygin.

  • gh-101015: Fix typing.get_type_hints() on '*tuple[...]' and *tuple[...]. It must not drop the Unpack part.

  • gh-101000: Add os.path.splitroot(), which splits a path into a 3-item tuple (drive, root, tail). This new function is used by pathlib to improve the performance of path construction by up to a third.

  • gh-100573: Fix a Windows asyncio bug with named pipes where a client doing os.stat() on the pipe would cause an error in the server that disabled serving future requests.

  • gh-39615: warnings.warn() now has the ability to skip stack frames based on code filename prefix rather than only a numeric stacklevel via the new skip_file_prefixes keyword argument.

  • gh-100750: pass encoding kwarg to subprocess in platform

  • gh-100160: Emit a deprecation warning in asyncio.DefaultEventLoopPolicy.get_event_loop() if there is no current event loop set and it decides to create one.

  • gh-96290: Fix handling of partial and invalid UNC drives in ntpath.splitdrive(), and in ntpath.normpath() on non-Windows systems. Paths such as ‘\server’ and ‘\’ are now considered by splitdrive() to contain only a drive, and consequently are not modified by normpath() on non-Windows systems. The behaviour of normpath() on Windows systems is unaffected, as native OS APIs are used. Patch by Eryk Sun, with contributions by Barney Gale.

  • gh-99952: Fix a reference undercounting issue in ctypes.Structure with from_param() results larger than a C pointer.

  • gh-67790: Add float-style formatting support for fractions.Fraction instances.

  • gh-99266: Preserve more detailed error messages in ctypes.

  • gh-86682: Ensure runtime-created collections have the correct module name using the newly added (internal) sys._getframemodulename().

  • gh-88597: uuid now has a command line interface. Try python -m uuid -h.

  • gh-60580: ctypes.wintypes.BYTE definition changed from c_byte to c_ubyte to match Windows SDK. Patch by Anatoly Techtonik and Oleg Iarygin.

  • gh-94518: _posixsubprocess now initializes all UID and GID variables using a reserved -1 value instead of a separate flag. Patch by Oleg Iarygin.

  • bpo-38941: The xml.etree.ElementTree module now emits DeprecationWarning when testing the truth value of an xml.etree.ElementTree.Element. Before, the Python implementation emitted FutureWarning, and the C implementation emitted nothing.

  • bpo-40077: Convert elementtree types to heap types. Patch by Erlend E. Aasland.

  • bpo-29847: Fix a bug where pathlib.Path accepted and ignored keyword arguments. Patch provided by Yurii Karabas.

  • gh-77772: ctypes.CDLL, ctypes.OleDLL, ctypes.WinDLL, and ctypes.PyDLL now accept path-like objects as their name argument. Patch by Robert Hoelzl.

Documentation

  • gh-88324: Reword subprocess to emphasize default behavior of stdin, stdout, and stderr arguments. Remove inaccurate statement about child file handle inheritance.

Tests

  • gh-101334: test_tarfile has been updated to pass when run as a high UID.

Build

  • gh-101282: Update BOLT configration not to use depreacted usage of --split functions. Patch by Donghee Na.

  • gh-101522: Allow overriding Windows dependencies versions and paths using MSBuild properties.

  • gh-77532: Minor fixes to allow building with PlatformToolset=ClangCL on Windows.

  • gh-101152: In accordance with PEP 699, the ma_version_tag field in PyDictObject is deprecated for extension modules. Accessing this field will generate a compiler warning at compile time. This field will be removed in Python 3.14.

  • gh-100340: Allows -Wno-int-conversion for wasm-sdk 17 and onwards, thus enables building WASI builds once against the latest sdk.

  • gh-101060: Conditionally add -fno-reorder-blocks-and-partition in configure. Effectively fixes --enable-bolt when using Clang, as this appears to be a GCC-only flag.

  • gh-98705: __bool__ is defined in AIX system header files which breaks the build in AIX, so undefine it.

  • gh-98636: Fix a regression in detecting gdbm_compat library for the _gdbm module build.

  • gh-96305: _aix_support now uses a simple code to get platform details rather than the now non-existent _bootsubprocess during bootstrap.

Windows

  • gh-101543: Ensure the install path in the registry is only used when the standard library hasn’t been located in any other way.

  • gh-101467: The py.exe launcher now correctly filters when only a single runtime is installed. It also correctly handles prefix matches on tags so that -3.1 does not match 3.11, but would still match 3.1-32.

  • gh-99834: Updates bundled copy of Tcl/Tk to 8.6.13.0

  • gh-101135: Restore ability to launch older 32-bit versions from the py.exe launcher when both 32-bit and 64-bit installs of the same version are available.

  • gh-82052: Fixed an issue where writing more than 32K of Unicode output to the console screen in one go can result in mojibake.

  • gh-100320: Ensures the PythonPath registry key from an install is used when launching from a different copy of Python that relies on an existing install to provide a copy of its modules and standard library.

  • gh-100247: Restores support for the py.exe launcher finding shebang commands in its configuration file using the full command name.

Python 3.12.0 alpha 4

Release date: 2023-01-10

Core and Builtins

  • gh-100776: Fix misleading default value in input()’s __text_signature__.

  • gh-99005: Remove UNARY_POSITIVE, ASYNC_GEN_WRAP and LIST_TO_TUPLE, replacing them with intrinsics.

  • gh-99005: Add new CALL_INTRINSIC_1 instruction. Remove IMPORT_STAR, PRINT_EXPR and STOPITERATION_ERROR, replacing them with the CALL_INTRINSIC_1 instruction.

  • gh-100288: Remove the LOAD_ATTR_METHOD_WITH_DICT specialized instruction. Stats show it is not useful.

  • gh-100720: Added _PyFrame_NumSlotsForCodeObject, which returns the number of slots needed in a frame for a given code object.

  • gh-100719: Removed the co_nplaincellvars field from the code object, as it is redundant.

  • gh-100637: Fix int.__sizeof__() calculation to include the 1 element ob_digit array for 0 and False.

  • gh-100649: Update the native_thread_id field of PyThreadState after fork.

  • gh-100126: Fix an issue where “incomplete” frames could be briefly visible to C code while other frames are being torn down, possibly resulting in corruption or hard crashes of the interpreter while running finalizers.

  • gh-87447: Fix SyntaxError on comprehension rebind checking with names that are not actually redefined.

    Now reassigning b in [(b := 1) for a, b.prop in some_iter] is allowed. Reassigning a is still disallowed as per PEP 572.

  • gh-100268: Add int.is_integer() to improve duck type compatibility between int and float.

  • gh-100425: Improve the accuracy of sum() with compensated summation.

  • gh-100374: Fix incorrect result and delay in socket.getfqdn(). Patch by Dominic Socular.

  • gh-100357: Convert vars, dir, next, getattr, and iter to argument clinic.

  • gh-100117: Improve the output of co_lines by emitting only one entry for each line range.

  • gh-90043: Handle NaNs when specializing COMPARE_OP for float values.

  • gh-100222: Redefine the _Py_CODEUNIT typedef as a union to describe its layout to the C compiler, avoiding type punning and improving clarity.

  • gh-99955: Internal compiler functions (in compile.c) now consistently return -1 on error and 0 on success.

  • gh-100188: The BINARY_SUBSCR_LIST_INT and BINARY_SUBSCR_TUPLE_INT instructions are no longer used for negative integers because those instructions always miss when encountering negative integers.

  • gh-99110: Initialize frame->previous in frameobject.c to fix a segmentation fault when accessing frames created by PyFrame_New().

  • gh-94155: Improved the hashing algorithm for code objects, mitigating some hash collisions.

  • gh-99540: None now hashes to a constant value. This is not a requirements change.

  • gh-100143: When built with --enable-pystats, stats collection is now off by default. To enable it early at startup, pass the -Xpystats flag. Stats are now always dumped, even if switched off.

  • gh-100146: Improve BUILD_LIST opcode so that it works similarly to the BUILD_TUPLE opcode, by stealing references from the stack rather than repeatedly using stack operations to set list elements. Implementation details are in a new private API _PyList_FromArraySteal().

  • gh-100110: Specialize FOR_ITER for tuples.

  • gh-100050: Honor existing errors obtained when searching for mismatching parentheses in the tokenizer. Patch by Pablo Galindo

  • gh-92216: Improve the performance of hasattr() for type objects with a missing attribute.

  • gh-99582: Freeze zipimport module into _bootstrap_python.

  • gh-99554: Pack debugging location tables more efficiently during bytecode compilation.

  • gh-98522: Add an internal version number to code objects, to give better versioning of inner functions and comprehensions, and thus better specialization of those functions. This change is invisible to both Python and C extensions.

  • gh-94603: Improve performance of list.pop for small lists.

  • gh-89051: Add ssl.OP_LEGACY_SERVER_CONNECT

  • bpo-32782: ctypes arrays of length 0 now report a correct itemsize when a memoryview is constructed from them, rather than always giving a value of 0.

Library

Documentation

Tests

  • gh-100454: Start running SSL tests with OpenSSL 3.1.0-beta1.

  • gh-100086: The Python test runner (libregrtest) now logs Python build information like “debug” vs “release” build, or LTO and PGO optimizations. Patch by Victor Stinner.

  • gh-93018: Make two tests forgiving towards host system libexpat with backported security fixes applied.

Build

  • gh-100540: Removed the --with-system-ffi configure option; libffi must now always be supplied by the system on all non-Windows platforms. The option has had no effect on non-Darwin platforms for several releases, and in 3.11 only had the non-obvious effect of invoking pkg-config to find libffi and never setting -DUSING_APPLE_OS_LIBFFI. Now on Darwin platforms configure will first check for the OS libffi and then fall back to the same processing as other platforms if it is not found.

  • gh-88267: Avoid exporting Python symbols in linked Windows applications when the core is built as static.

  • bpo-41916: Allow override of ac_cv_cxx_thread so that cross compiled python can set -pthread for CXX.

Windows

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

  • gh-99191: Use _MSVC_LANG >= 202002L instead of less-precise _MSC_VER >=1929 to more accurately test for C++20 support in PC/_wmimodule.cpp.

  • gh-79218: Define MS_WIN64 for Mingw-w64 64bit, fix cython compilation failure.

  • gh-99941: Ensure that asyncio.Protocol.data_received() receives an immutable bytes object (as documented), instead of bytearray.

  • bpo-43984: winreg.SetValueEx() now leaves the target value untouched in the case of conversion errors. Previously, -1 would be written in case of such errors.

  • bpo-34816: hasattr(ctypes.windll, 'nonexistant') now returns False instead of raising OSError.

macOS

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

  • gh-100540: Removed obsolete dlfcn.h shim from the _ctypes extension module, which has not been necessary since Mac OS X 10.2.

Tools/Demos

  • bpo-45256: Fix a bug that caused an AttributeError to be raised in python-gdb.py when py-locals is used without a frame.

  • gh-100342: Add missing NULL check for possible allocation failure in *args parsing in Argument Clinic.

C API

  • gh-99947: Raising SystemError on import will now have its cause be set to the original unexpected exception.

  • gh-99240: In argument parsing, after deallocating newly allocated memory, reset its pointer to NULL.

  • gh-98724: The Py_CLEAR, Py_SETREF and Py_XSETREF macros now only evaluate their arguments once. If an argument has side effects, these side effects are no longer duplicated. Patch by Victor Stinner.

Python 3.12.0 alpha 3

Release date: 2022-12-06

Security

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

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

  • gh-87604: Avoid publishing list of active per-interpreter audit hooks via the gc module

Core and Builtins

  • gh-99891: Fix a bug in the tokenizer that could cause infinite recursion when showing syntax warnings that happen in the first line of the source. Patch by Pablo Galindo

  • gh-91054: Add PyCode_AddWatcher() and PyCode_ClearWatcher() APIs to register callbacks to receive notification on creation and destruction of code objects.

  • gh-99729: Fix an issue that could cause frames to be visible to Python code as they are being torn down, possibly leading to memory corruption or hard crashes of the interpreter.

  • gh-99708: Fix bug where compiler crashes on an if expression with an empty body block.

  • gh-99578: Fix a reference bug in _imp.create_builtin() after the creation of the first sub-interpreter for modules builtins and sys. Patch by Victor Stinner.

  • gh-99581: Fixed a bug that was causing a buffer overflow if the tokenizer copies a line missing the newline caracter from a file that is as long as the available tokenizer buffer. Patch by Pablo galindo

  • gh-99553: Fix bug where an ExceptionGroup subclass can wrap a BaseException.

  • gh-99547: Add a function to os.path to check if a path is a junction: isjunction. Add similar functionality to pathlib.Path as is_junction.

  • gh-99370: Fix zip path for venv created from a non-installed python on POSIX platforms.

  • gh-99377: Add audit events for thread creation and clear operations.

  • gh-98686: Remove the BINARY_OP_GENERIC and COMPARE_OP_GENERIC “specializations”.

  • gh-99298: Remove the remaining error paths for attribute specializations, and refuse to specialize attribute accesses on types that haven’t had PyType_Ready() called on them yet.

  • gh-99127: Allow some features of syslog to the main interpreter only. Patch by Donghee Na.

  • gh-91053: Optimizing interpreters and JIT compilers may need to invalidate internal metadata when functions are modified. This change adds the ability to provide a callback that will be invoked each time a function is created, modified, or destroyed.

  • gh-90994: Improve error messages when there’s a syntax error with call arguments. The following three cases are covered: - No value is assigned to a named argument, eg foo(a=). - A value is assigned to a star argument, eg foo(*args=[0]). - A value is assigned to a double-star keyword argument, eg foo(**kwarg={'a': 0}).

  • bpo-45026: Optimize the range object iterator. It is now smaller, faster iteration of ranges containing large numbers. Smaller pickles, faster unpickling.

  • bpo-31718: Raise ValueError instead of SystemError when methods of uninitialized io.IncrementalNewlineDecoder objects are called. Patch by Oren Milman.

  • bpo-38031: Fix a possible assertion failure in io.FileIO when the opener returns an invalid file descriptor.

Library

  • gh-100001: Also escape s in the http.server BaseHTTPRequestHandler.log_message so that it is technically possible to parse the line and reconstruct what the original data was. Without this a xHH is ambiguious as to if it is a hex replacement we put in or the characters r”x” came through in the original request line.

  • gh-99957: Add frozen_default parameter to typing.dataclass_transform().

  • gh-79033: Fix asyncio.Server.wait_closed() to actually do what the docs promise – wait for all existing connections to complete, after closing the server.

  • gh-51524: Fix bug when calling trace.CoverageResults with valid infile.

  • gh-99645: Fix a bug in handling class cleanups in unittest.TestCase. Now addClassCleanup() uses separate lists for different TestCase subclasses, and doClassCleanups() only cleans up the particular class.

  • gh-99508: Fix TypeError in Lib/importlib/_bootstrap_external.py while calling _imp.source_hash().

  • gh-66285: Fix asyncio to not share event loop and signal wakeupfd in forked processes. Patch by Kumar Aditya.

  • gh-97001: Release the GIL when calling termios APIs to avoid blocking threads.

  • gh-92647: Use final status of an enum to determine lookup or creation branch of functional API.

  • gh-99388: Add loop_factory parameter to asyncio.run() to allow specifying a custom event loop factory. Patch by Kumar Aditya.

  • gh-99341: Fix ast.increment_lineno() to also cover ast.TypeIgnore when changing line numbers.

  • gh-99382: Check the number of arguments in substitution in user generics containing a TypeVarTuple and one or more TypeVar.

  • gh-99379: Fix substitution of ParamSpec followed by TypeVarTuple in generic aliases.

  • gh-99344: Fix substitution of TypeVarTuple and ParamSpec together in user generics.

  • gh-99284: Remove _use_broken_old_ctypes_structure_semantics_ old untested and undocumented hack from ctypes.

  • gh-99201: Fix IndexError when initializing the config variables on Windows if HAVE_DYNAMIC_LOADING is not set.

  • gh-99240: Fix double-free bug in Argument Clinic str_converter by extracting memory clean up to a new post_parsing section.

  • gh-64490: Fix refcount error when arguments are packed to tuple in Argument Clinic.

  • gh-99029: pathlib.PurePath.relative_to() now treats naked Windows drive paths as relative. This brings its behaviour in line with other parts of pathlib.

  • gh-98253: The implementation of the typing module is now more resilient to reference leaks in binary extension modules.

    Previously, a reference leak in a typed C API-based extension module could leak internals of the typing module, which could in turn introduce leaks in essentially any other package with typed function signatures. Although the typing package is not the original source of the problem, such non-local dependences exacerbate debugging of large-scale projects, and the implementation was therefore changed to reduce harm by providing better isolation.

  • gh-98458: Fix infinite loop in unittest when a self-referencing chained exception is raised

  • gh-93453: asyncio.get_event_loop() and many other asyncio functions like asyncio.ensure_future(), asyncio.shield() or asyncio.gather(), and also the get_event_loop() method of asyncio.BaseDefaultEventLoopPolicy now raise a RuntimeError if called when there is no running event loop and the current event loop was not set. Previously they implicitly created and set a new current event loop. DeprecationWarning is no longer emitted if there is no running event loop but the current event loop was set.

  • gh-97966: On uname_result, restored expectation that _fields and _asdict would include all six properties including processor.

  • gh-98248: Provide informative error messages in struct.pack() when its integral arguments are not in range.

  • gh-98108: zipfile.Path is now pickleable if its initialization parameters were pickleable (e.g. for file system paths).

  • gh-98098: Created packages from zipfile and test_zipfile modules, separating zipfile.Path functionality.

  • gh-82836: Fix is_private properties in the ipaddress module. Previously non-private networks (0.0.0.0/0) would return True from this method; now they correctly return False.

  • gh-96828: Add an OP_ENABLE_KTLS option for enabling the use of the kernel TLS (kTLS). Patch by Illia Volochii.

  • gh-88863: To avoid apparent memory leaks when asyncio.open_connection() raises, break reference cycles generated by local exception and future instances (which has exception instance as its member var). Patch by Dong Uk, Kang.

  • gh-91078: TarFile.next() now returns None when called on an empty tarfile.

  • bpo-47220: Document the optional callback parameter of WeakMethod. Patch by Géry Ogam.

  • bpo-44817: Ignore WinError 53 (ERROR_BAD_NETPATH), 65 (ERROR_NETWORK_ACCESS_DENIED) and 161 (ERROR_BAD_PATHNAME) when using ntpath.realpath().

  • bpo-41260: Rename the fmt parameter of the pure Python implementation of datetime.date.strftime() to format.

  • bpo-15999: All built-in functions now accept arguments of any type instead of just bool and int for boolean parameters.

Documentation

  • gh-99931: Use sphinxext-opengraph to generate OpenGraph metadata.

  • gh-89682: Reworded docstring of the default __contains__ to clarify that it returns a bool.

  • gh-88330: Improved the description of what a resource is in importlib.resources docs.

  • gh-92892: Document that calling variadic functions with ctypes requires special care on macOS/arm64 (and possibly other platforms).

  • bpo-41825: Restructured the documentation for the os.wait* family of functions, and improved the docs for os.waitid() with more explanation of the possible argument constants.

Tests

  • gh-99892: Skip test_normalization() of test_unicodedata if it fails to download NormalizationTest.txt file from pythontest.net. Patch by Victor Stinner.

  • gh-99934: Correct test_marsh on (32 bit) x86: test_deterministic sets was failing.

  • gh-99741: We’ve implemented multi-phase init (PEP 489/630/687) for the internal (for testing) _xxsubinterpreters module.

  • gh-99659: Optional big memory tests in test_sqlite3 now catch the correct sqlite.DataError exception type in case of too large strings and/or blobs passed.

  • gh-99593: Cover the Unicode C API with tests.

  • gh-96002: Add functional test for Argument Clinic.

Build

  • gh-99086: Fix -Wimplicit-int, -Wstrict-prototypes, and -Wimplicit-function-declaration compiler warnings in configure checks.

  • gh-99337: Fix a compilation issue with GCC 12 on macOS.

  • gh-99289: Add a COMPILEALL_OPTS variable in Makefile to override compileall options (default: -j0) in make install. Also merged the compileall commands into a single command building .pyc files for the all optimization levels (0, 1, 2) at once. Patch by Victor Stinner.

  • gh-98872: Fix a possible fd leak in Programs/_freeze_module.c introduced in Python 3.11.

  • gh-88226: Always define TARGET_* labels in Python/ceval.c, even if USE_COMPUTED_GOTOS is disabled. This allows breakpoints to be set at those labels in (for instance) gdb.

Windows

macOS

  • gh-87235: On macOS python3 /dev/fd/9 9</path/to/script.py failed for any script longer than a couple of bytes.

  • gh-98940: Fix Mac/Extras.install.py file filter bug.

Tools/Demos

  • gh-64490: Argument Clinic varargs bugfixes

    • Fix out-of-bounds error in _PyArg_UnpackKeywordsWithVararg().

    • Fix incorrect check which allowed more than one varargs in clinic.py.

    • Fix miscalculation of noptargs in generated code.

    • Do not generate noptargs when there is a vararg argument and no optional argument.

C API

  • gh-98680: PyBUF_* constants were marked as part of Limited API of Python 3.11+. These were available in 3.11.0 with Py_LIMITED_API defined for 3.11, and are necessary to use the buffer API.

  • gh-99612: Fix PyUnicode_DecodeUTF8Stateful() for ASCII-only data: *consumed was not set.

  • gh-47146: The structmember.h header is deprecated. Its non-deprecated contents are now available just by including Python.h, with a Py_ prefix added if it was missing. (Deprecated contents are T_OBJECT, T_NONE, and no-op flags.) Patch by Petr Viktorin, based on earlier work by Alexander Belopolsky and Matthias Braun.

Python 3.12.0 alpha 2

Release date: 2022-11-14

Security

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

    Individual labels within an IDNA encoded DNS name will now raise an error early during IDNA decoding if they are longer than 1024 unicode characters given that each decoded DNS label must be 63 or fewer characters and the entire decoded DNS name is limited to 255. Only an application presenting a hostname or label consisting primarily of RFC 3454 section 3.1 “Nothing” characters to be removed would run into of this new limit. See also RFC 5894 section 6 and RFC 3491.

  • gh-98739: Update bundled libexpat to 2.5.0

Core and Builtins

  • gh-81057: The docs clearly say that PyImport_Inittab, PyImport_AppendInittab(), and PyImport_ExtendInittab() should not be used after Py_Initialize() has been called. We now enforce this for the two functions. Additionally, the runtime now uses an internal copy of PyImport_Inittab, to guard against modification.

  • gh-99298: Fix an issue that could potentially cause incorrect error handling for some bytecode instructions.

  • gh-99254: The compiler now removes all unused constants from code objects (except the first one, which may be a docstring).

  • gh-99205: Fix an issue that prevented PyThreadState and PyInterpreterState memory from being freed properly.

  • gh-81057: The 18 global C variables holding the state of the allocators have been moved to _PyRuntimeState. This is a strictly internal change with no change in behavior.

  • gh-99181: Fix failure in except* with unhashable exceptions.

  • gh-99204: Fix calculation of sys._base_executable when inside a POSIX virtual environment using copies of the python binary when the base installation does not provide the executable name used by the venv. Calculation will fall back to alternative names (“python<MAJOR>”, “python<MAJOR>.<MINOR>”).

  • gh-96055: Update faulthandler to emit an error message with the proper unexpected signal number. Patch by Donghee Na.

  • gh-99153: Fix location of SyntaxError for a try block with both except and except*.

  • gh-98686: Merge the adaptive opcode logic into each instruction’s unquickened variant, and merge the logic in EXTENDED_ARG_QUICK into EXTENDED_ARG. With these changes, the quickening that happens at code object creation is now only responsible for initializing warmup counters and inserting superinstructions.

  • gh-99103: Fix the error reporting positions of specialized traceback anchors when the source line contains Unicode characters.

  • gh-99139: Improve the error suggestion for NameError exceptions for instances. Now if a NameError is raised in a method and the instance has an attribute that’s exactly equal to the name in the exception, the suggestion will include self.<NAME> instead of the closest match in the method scope. Patch by Pablo Galindo

  • gh-98401: Octal escapes with value larger than 0o377 (ex: "\477"), deprecated in Python 3.11, now produce a SyntaxWarning, instead of DeprecationWarning. In a future Python version they will be eventually a SyntaxError. Patch by Victor Stinner.

  • gh-98401: A backslash-character pair that is not a valid escape sequence now generates a SyntaxWarning, instead of DeprecationWarning. For example, re.compile("\d+\.\d+") now emits a SyntaxWarning ("\d" is an invalid escape sequence), use raw strings for regular expression: re.compile(r"\d+\.\d+"). In a future Python version, SyntaxError will eventually be raised, instead of SyntaxWarning. Patch by Victor Stinner.

  • gh-96793: Handle StopIteration and StopAsyncIteration raised in generator or coroutines in the bytecode, rather than in wrapping C code.

  • gh-98931: Improve the SyntaxError error message when the user types import x from y instead of from y import x. Patch by Pablo Galindo

  • gh-98852: Fix subscription of type aliases containing bare generic types or types like TypeVar: for example tuple[A, T][int] and tuple[TypeVar, T][int], where A is a generic type, and T is a type variable.

  • gh-98925: Lower the recursion depth for marshal on WASI to support (in-development) wasmtime 2.0.

  • gh-98783: Fix multiple crashes in debug mode when str subclasses are used instead of str itself.

  • gh-98811: Use complete source locations to simplify detection of __future__ imports which are not at the beginning of the file. Also corrects the offset in the exception raised in one case, which was off by one and impeded highlighting.

  • gh-96793: Add specialization of FOR_ITER for generators. Saves multiple layers of dispatch and checking to get from the FOR_ITER instruction in the caller to the RESUME in the generator.

  • gh-98762: Fix source locations of match sub-patterns.

  • gh-98586: Added the methods PyObject_Vectorcall() and PyObject_VectorcallMethod() to the Limited API along with the auxiliary macro constant PY_VECTORCALL_ARGUMENTS_OFFSET.

    The availability of these functions enables more efficient PEP 590 vector calls from binary extension modules that avoid argument boxing/unboxing overheads.

  • gh-99257: Fix an issue where member descriptors (such as those for __slots__) could behave incorrectly or crash instead of raising a TypeError when accessed via an instance of an invalid type.

  • gh-93143: Rather than changing co_code, the interpreter will now display a RuntimeWarning and assign None to any fast locals that are left unbound after jumps or del statements executed while tracing.

  • gh-96421: When calling into Python code from C code, through PyEval_EvalFrameEx() or a related C-API function, a shim frame in inserted into the call stack. This occurs in the _PyEval_EvalFrameDefault() function. The extra frame should be invisible to all Python and most C extensions, but out-of-process profilers and debuggers need to be aware of it. These shim frames can be detected by checking frame->owner == FRAME_OWNED_BY_CSTACK.

    Extensions implementing their own interpreters using PEP 523 need to be aware of this shim frame and the changes to the semantics of RETURN_VALUE, YIELD_VALUE, and RETURN_GENERATOR, which now clear the frame.

  • gh-98415: Fix detection of MAC addresses for uuid on certain OSs. Patch by Chaim Sanders

  • gh-98686: Quicken all code objects, and specialize adaptive bytecode instructions more aggressively.

  • gh-92119: Print exception class name instead of its string representation when raising errors from ctypes calls.

  • gh-91058: ImportError raised from failed from <module> import <name> now include suggestions for the value of <name> based on the available names in <module>. Patch by Pablo Galindo

  • gh-96793: The FOR_ITER now leaves the iterator on the stack on termination of the loop. This is to assist specialization of loops for generators.

  • gh-90716: Add _pylong.py module. It includes asymptotically faster algorithms that can be used for operations on integers with many digits. It is used by longobject.c to speed up some operations.

  • gh-95389: Expose ETH_P_ALL and some of the ETHERTYPE_* constants in socket. Patch by Noam Cohen.

  • gh-93696: Allow pdb to locate source for frozen modules in the standard library.

Library

  • gh-99418: Fix bug in urllib.parse.urlparse() that causes URL schemes that begin with a digit, a plus sign, or a minus sign to be parsed incorrectly.

  • gh-94597: Deprecate asyncio.AbstractChildWatcher to be removed in Python 3.14. Patch by Kumar Aditya.

  • gh-99305: Improve performance of secrets.token_hex().

  • gh-74044: Fixed bug where inspect.signature() reported incorrect arguments for decorated methods.

  • gh-99275: Fix SystemError in ctypes when exception was not set during __initsubclass__.

  • gh-99277: Remove older version of _SSLProtocolTransport.get_write_buffer_limits in asyncio.sslproto

  • gh-99248: fix negative numbers failing in verify()

  • gh-99155: Fix statistics.NormalDist pickle with 0 and 1 protocols.

  • gh-93464: enum.auto() is now correctly activated when combined with other assignment values. E.g. ONE = auto(), 'some text' will now evaluate as (1, 'some text').

  • gh-99134: Update the bundled copy of pip to version 22.3.1.

  • gh-92584: Remove the distutils package. It was deprecated in Python 3.10 by PEP 632 “Deprecate distutils module”. For projects still using distutils and cannot be updated to something else, the setuptools project can be installed: it still provides distutils. Patch by Victor Stinner.

  • gh-98999: Now _pyio is consistent with _io in raising ValueError when executing methods over closed buffers.

  • gh-83004: Clean up refleak on failed module initialisation in _zoneinfo

  • gh-83004: Clean up refleaks on failed module initialisation in _pickle

  • gh-83004: Clean up refleak on failed module initialisation in _io.

  • gh-98897: Fix memory leak in math.dist() when both points don’t have the same dimension. Patch by Kumar Aditya.

  • gh-98878: Use the frame bound builtins when offering a name suggestion in traceback to prevent crashing when __builtins__ is not a dict.

  • gh-98139: In importlib._bootstrap, enhance namespace package repr to <module 'x' (namespace) from ['path']>.

  • gh-90352: Fix _SelectorDatagramTransport to inherit from DatagramTransport in asyncio. Patch by Kumar Aditya.

  • gh-98793: Fix argument typechecks in _overlapped.WSAConnect() and _overlapped.Overlapped.WSASendTo() functions.

  • gh-98744: Prevent crashing in traceback when retrieving the byte-offset for some source files that contain certain unicode characters.

  • gh-98740: Fix internal error in the re module which in very rare circumstances prevented compilation of a regular expression containing a conditional expression without the “else” branch.

  • gh-98703: Fix asyncio.StreamWriter.drain() to call protocol.connection_lost callback only once on Windows.

  • gh-98624: Add a mutex to unittest.mock.NonCallableMock to protect concurrent access to mock attributes.

  • gh-98658: The array.array class now supports subscripting, making it a generic type.

  • gh-98284: Improved TypeError message for undefined abstract methods of a abc.ABC instance. The names of the missing methods are surrounded by single-quotes to highlight them.

  • gh-96151: Allow BUILTINS to be a valid field name for frozen dataclasses.

  • gh-98086: Make sure patch.dict() can be applied on async functions.

  • gh-72719: Remove modules asyncore and asynchat, which were deprecated by PEP 594.

  • gh-96192: Fix handling of bytes path-like objects in os.ismount().

  • gh-94172: ftplib: Remove the FTP_TLS.ssl_version class attribute: use the context parameter instead. Patch by Victor Stinner

  • gh-94172: Remove the keyfile and certfile parameters from the ftplib, imaplib, poplib and smtplib modules, and the key_file, cert_file and check_hostname parameters from the http.client module, all deprecated since Python 3.6. Use the context parameter (ssl_context in imaplib) instead. Patch by Victor Stinner.

  • gh-83638: Add the autocommit attribute to sqlite3.Connection and the autocommit parameter to sqlite3.connect() to control PEP 249-compliant transaction handling. Patch by Erlend E. Aasland.

  • gh-92452: Fixed a race condition that could cause sysconfig.get_config_var() to incorrectly return None in multi-threaded programs.

  • gh-91803: Fix an error when using a method of objects mocked with unittest.mock.create_autospec() after it was sealed with unittest.mock.seal() function.

  • bpo-38523: shutil.copytree() now applies the ignore_dangling_symlinks argument recursively.

  • bpo-40358: Add walk_up argument in pathlib.PurePath.relative_to().

  • bpo-36267: Fix IndexError in argparse.ArgumentParser when a store_true action is given an explicit argument.

Documentation

  • gh-98832: Changes wording of docstring for pathlib.Path.iterdir().

  • gh-97966: Update uname docs to clarify the special nature of the platform attribute and to indicate when it became late-bound.

Tests

  • gh-98903: The Python test suite now fails wit exit code 4 if no tests ran. It should help detecting typos in test names and test methods.

  • gh-98713: Fix a bug in the typing tests where a test relying on CPython-specific implementation details was not decorated with @cpython_only and was not skipped on other implementations.

  • gh-87390: Add tests for star-unpacking with PEP 646, and some other miscellaneous PEP 646 tests.

  • gh-96853: Added explicit coverage of Py_Initialize (and hence Py_InitializeEx) back to the embedding tests (all other embedding tests migrated to Py_InitializeFromConfig in Python 3.11)

  • bpo-34272: Some C API tests were moved into the new Lib/test/test_capi/ directory.

Build

  • gh-99086: Fix -Wimplicit-int compiler warning in configure check for PTHREAD_SCOPE_SYSTEM.

  • gh-99016: Fix build with PYTHON_FOR_REGEN=python3.8.

  • gh-97731: Specify the full path to the source location for make docclean (needed for cross-builds).

  • gh-98949: Drop unused build dependency on readelf.

  • gh-98989: Use python3.11, if available, for regeneration and freezing.

  • gh-98831: Add new tooling, in Tools/cases_generator, to generate the interpreter switch statement from a list of opcode definitions. This only affects adding, modifying or removing instruction definitions. The instruction definitions now live in Python/bytecodes.c, in the form of a custom DSL (under development). The tooling reads this file and writes Python/generated_cases.c.h, which is then included by Python/ceval.c to provide most of the cases of the main interpreter switch.

  • gh-98817: Remove PCbuild/lib.pyproj: it’s not used for anything, is only a minor convenience for Visual Studio users (who probably mostly don’t even know about it), and it takes a lot of maintenance effort to keep updated.

  • gh-98776: Fix make regen-test-levenshtein for out-of-tree builds.

  • gh-98707: Don’t use vendored libmpdec headers if --with-system-libmpdec is passed to configure. Don’t use vendored libexpat headers if --with-system-expat is passed to configure.

Windows

  • gh-98689: Update Windows builds to zlib v1.2.13. v1.2.12 has CVE-2022-37434, but the vulnerable inflateGetHeader API is not used by Python.

  • gh-98790: Assumes that a missing DLLs directory means that standard extension modules are in the executable’s directory.

  • gh-98745: Update py.exe launcher to install 3.11 by default and 3.12 on request.

  • gh-98692: Fix the Python Launcher for Windows ignoring unrecognized shebang lines instead of treating them as local paths

  • gh-94328: Update Windows installer to use SQLite 3.39.4.

macOS

  • gh-94328: Update macOS installer to SQLite 3.39.4.

C API

  • gh-98724: The Py_CLEAR, Py_SETREF and Py_XSETREF macros now only evaluate their argument once. If the argument has side effects, these side effects are no longer duplicated. Patch by Victor Stinner.

  • gh-98978: Fix use-after-free in Py_SetPythonHome(NULL), Py_SetProgramName(NULL) and _Py_SetProgramFullPath(NULL) function calls. Issue reported by Benedikt Reinartz. Patch by Victor Stinner.

  • gh-98410: Add getbufferproc and releasebufferproc to the stable API.

  • gh-98610: Some configurable capabilities of sub-interpreters have changed. They always allow subprocesses (subprocess) now, whereas before subprocesses could be optionally disallowed for a sub-interpreter. Instead os.exec() can now be disallowed. Disallowing daemon threads is now supported. Disallowing all threads is still allowed, but is never done by default. Note that the optional restrictions are only available through _Py_NewInterpreterFromConfig(), which isn’t a public API. They do not affect the main interpreter, nor Py_NewInterpreter().

  • gh-98608: A _PyInterpreterConfig has been added and _Py_NewInterpreter() has been renamed to _Py_NewInterpreterFromConfig(). The “isolated_subinterpreters” argument is now a granular config that captures the previous behavior. Note that this is all “private” API.

  • gh-96853: Py_InitializeEx now correctly calls PyConfig_Clear after initializing the interpreter (the omission didn’t cause a memory leak only because none of the dynamically allocated config fields are populated by the wrapper function)

  • gh-91248: Add PyFrame_GetVar() and PyFrame_GetVarString() functions to get a frame variable by its name. Patch by Victor Stinner.

Python 3.12.0 alpha 1

Release date: 2022-10-25

Security

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

  • gh-97514: On Linux the multiprocessing module returns to using filesystem backed unix domain sockets for communication with the forkserver process instead of the Linux abstract socket namespace. Only code that chooses to use the “forkserver” start method is affected.

    Abstract sockets have no permissions and could allow any user on the system in the same network namespace (often the whole system) to inject code into the multiprocessing forkserver process. This was a potential privilege escalation. Filesystem based socket permissions restrict this to the forkserver process user as was the default in Python 3.8 and earlier.

    This prevents Linux CVE-2022-42919.

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

  • gh-79096: LWPCookieJar and MozillaCookieJar create files with file mode 600 instead of 644 (Microsoft Windows is not affected)

  • gh-92888: Fix memoryview use after free when accessing the backing buffer in certain cases.

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

Core and Builtins

  • gh-98374: Suppress ImportError for invalid query for help() command. Patch by Donghee Na.

  • gh-98461: Fix source location in bytecode for list, set and dict comprehensions as well as generator expressions.

  • gh-98354: Added unicode check for name attribute of spec argument passed in _imp.create_builtin() function.

  • gh-98398: Fix source location of ‘assert’ bytecodes.

  • gh-98390: Fix location of sub-expressions of boolean expressions, by reducing their scope to that of the sub-expression.

  • gh-98254: Modules from the standard library are now potentially suggested as part of the error messages displayed by the interpreter when an NameError is raised to the top level. Patch by Pablo Galindo

  • gh-97997: Add running column offset to the tokenizer state to avoid calculating AST column information with pointer arithmetic.

  • gh-97973: Modify the tokenizer to return all necessary information the parser needs to set location information in the AST nodes, so that the parser does not have to calculate those doing pointer arithmetic.

  • gh-96078: os.sched_yield() now release the GIL while calling sched_yield(2). Patch by Donghee Na.

  • gh-97955: Migrate zoneinfo to Argument Clinic.

  • gh-97912: The compiler now avoids quadratic behavior when finding which instructions should use the LOAD_FAST_CHECK opcode.

  • gh-97002: Fix an issue where several frame objects could be backed by the same interpreter frame, possibly leading to corrupted memory and hard crashes of the interpreter.

  • gh-97943: Bugfix: PyFunction_GetAnnotations() should return a borrowed reference. It was returning a new reference.

  • gh-97922: The Garbage Collector now runs only on the eval breaker mechanism of the Python bytecode evaluation loop instead on object allocations. The GC can also run when PyErr_CheckSignals() is called so C extensions that need to run for a long time without executing any Python code also have a chance to execute the GC periodically.

  • gh-65961: When __package__ is different than __spec__.parent, raise a DeprecationWarning instead of ImportWarning.

    Also remove importlib.util.set_package() which was scheduled for removal.

  • gh-97850: Long deprecated, module_repr() should now be completely eradicated.

  • gh-86298: In cases where warnings.warn_explicit() consults the module’s loader, an DeprecationWarning is issued when m.__loader__ differs from m.__spec__.loader.

  • gh-97779: Ensure that all Python frame objects are backed by “complete” frames.

  • gh-91052: Add API for subscribing to modification events on selected dictionaries.

  • gh-97752: Fix possible data corruption or crashes when accessing the f_back member of newly-created generator or coroutine frames.

  • gh-97591: Fixed a missing incref/decref pair in Exception.__setstate__(). Patch by Ofey Chan.

  • gh-97670: Remove the sys.getdxp() function and the Tools/scripts/analyze_dxp.py script. DXP stands for “dynamic execution pairs”. They were related to DYNAMIC_EXECUTION_PROFILE and DXPAIRS macros which have been removed in Python 3.11. Python can now be built with ./configure --enable-pystats to gather statistics on Python opcodes. Patch by Victor Stinner.

  • gh-94526: Fix the Python path configuration used to initialized sys.path at Python startup. Paths are no longer encoded to UTF-8/strict to avoid encoding errors if it contains surrogate characters (bytes paths are decoded with the surrogateescape error handler). Patch by Victor Stinner.

  • gh-96670: The parser now raises SyntaxError when parsing source code containing null bytes. Patch by Pablo Galindo

  • gh-96975: Fix a crash occurring when PyEval_GetFrame() is called while the topmost Python frame is in a partially-initialized state.

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

  • gh-95921: Fix overly-broad source position information for chained comparisons used as branching conditions.

  • gh-96821: Fix undefined behaviour in audioop.c.

  • gh-96821: Fix undefined behaviour in _testcapimodule.c.

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

  • gh-96387: At Python exit, sometimes a thread holding the GIL can wait forever for a thread (usually a daemon thread) which requested to drop the GIL, whereas the thread already exited. To fix the race condition, the thread which requested the GIL drop now resets its request before exiting. Issue discovered and analyzed by Mingliang ZHAO. Patch by Victor Stinner.

  • gh-96864: Fix a possible assertion failure, fatal error, or SystemError if a line tracing event raises an exception while opcode tracing is enabled.

  • gh-95778: The PyLong_FromString function was refactored to make it more maintainable and extensible.

  • gh-96678: Fix undefined behaviour in C code of null pointer arithmetic.

  • gh-96754: Make sure that all frame objects created are created from valid interpreter frames. Prevents the possibility of invalid frames in backtraces and signal handlers.

  • gh-90997: Improve the performance of reading and writing inline bytecode caches on some platforms.

  • gh-96751: Remove dead code from CALL_FUNCTION_EX opcode.

  • gh-90751: memoryview now supports half-floats. Patch by Donghee Na and Antoine Pitrou.

  • gh-96678: Fix case of undefined behavior in ceval.c

  • gh-64373: Convert _functools to argument clinic.

  • gh-96641: Do not expose KeyWrapper in _functools.

  • gh-96636: Ensure that tracing, sys.setrace(), is turned on immediately. In pre-release versions of 3.11, some tracing events might have been lost when turning on tracing in a __del__ method or interrupt.

  • gh-96572: Fix use after free in trace refs build mode. Patch by Kumar Aditya.

  • gh-96611: When loading a file with invalid UTF-8 inside a multi-line string, a correct SyntaxError is emitted.

  • gh-96612: Make sure that incomplete frames do not show up in tracemalloc traces.

  • gh-90230: Fix compiler warnings and test failures when building with --enable-pystats.

  • gh-96587: Correctly raise SyntaxError on exception groups (PEP 654) on python versions prior to 3.11

  • gh-96569: Remove two cases of undefined behavoir, by adding NULL checks.

  • gh-96582: Fix possible NULL pointer dereference in _PyThread_CurrentFrames. Patch by Kumar Aditya.

  • gh-91079: Separate Python recursion checking from C recursion checking which reduces the chance of C stack overflow and allows the recursion limit to be increased safely.

  • gh-93911: Fix an issue that could prevent LOAD_ATTR from specializing properly when accessing properties.

  • gh-96348: Emit a DeprecationWarning when throw(), throw() or athrow() are called with more than one argument.

  • gh-95196: Disable incorrect pickling of the C implemented classmethod descriptors.

  • gh-96364: Fix text signatures of list.__getitem__ and dict.__getitem__.

  • gh-96352: Fix AttributeError missing name and obj attributes in object.__getattribute__(). Patch by Philip Georgi.

  • gh-93554: Change the jump opcodes so that all conditional jumps are forward jumps. Backward jumps are converted by the assembler into a conditional forward jump whose target is the fallthrough block (and with a reversed condition), followed by an unconditional backward jump. For example:

    POP_JUMP_IF_TRUE BACKWARD_TARGET becomes POP_JUMP_IF_FALSE NEXT_BLOCK; JUMP BACKWARD_TARGET.

    All the directed conditional jump opcodes were removed: POP_JUMP_FORWARD_IF_TRUE, POP_JUMP_BACKWARD_IF_TRUE, POP_JUMP_FORWARD_IF_FALSE, POP_JUMP_BACKWARD_IF_FALSE, POP_JUMP_FORWARD_IF_NONE, POP_JUMP_BACKWARD_IF_NONE, POP_JUMP_FORWARD_IF_NOT_NONE, POP_JUMP_BACKWARD_IF_NOT_NONE.

    The corresponding opcodes without direction are no longer pseudo-instructions, and they implement the forward conditional jumps.

  • gh-96268: Loading a file with invalid UTF-8 will now report the broken character at the correct location.

  • gh-96237: The internal field _PyInterpreterFrame.f_func is renamed to _PyInterpreterFrame.f_funcobj and may be any object. The f_globals and f_builtin fields may hold junk values.

    It is safest to treat the _PyInterpreterFrame struct as opaque.

  • gh-96187: Fixed a bug that caused _PyCode_GetExtra to return garbage for negative indexes. Patch by Pablo Galindo

  • gh-96143: Add a new -X perf Python command line option as well as sys.activate_stack_trampoline() and sys.deactivate_stack_trampoline() function in the sys module that allows to set/unset the interpreter in a way that the Linux perf profiler can detect Python calls. The new sys.is_stack_trampoline_active() function allows to query the state of the perf trampoline. Design by Pablo Galindo. Patch by Pablo Galindo and Christian Heimes with contributions from Gregory P. Smith [Google] and Mark Shannon.

  • gh-96071: Fix a deadlock in PyGILState_Ensure() when allocating new thread state. Patch by Kumar Aditya.

  • gh-96046: PyType_Ready() now initializes ht_cached_keys and performs additional checks to ensure that type objects are properly configured. This avoids crashes in 3rd party packages that don’t use regular API to create new types.

  • gh-96005: On WASI ENOTCAPABLE is now mapped to PermissionError. The errno modules exposes the new error number. getpath.py now ignores PermissionError when it cannot open landmark files pybuilddir.txt and pyenv.cfg.

  • gh-93678: Added test a harness for direct unit tests of the compiler’s optimization stage. The _testinternalcapi.optimize_cfg() function runs the optimiser on a sequence of instructions. The CfgOptimizationTestCase class in test.support has utilities for invoking the optimizer and checking the output.

  • gh-95245: Reduces the size of a “simple” Python object from 8 to 6 words by moving the weakreflist pointer into the pre-header directly before the object’s dict/values pointer.

  • gh-90997: Compile virtual try/except blocks to handle exceptions raised during close() or throw() calls through a suspended frame.

  • gh-95977: Optimized calling __get__() with vectorcall. Patch by Kumar Aditya.

  • gh-91210: Improve error message when a parameter without a default value follows one with a default value, and show the same message, even when the non-default/default sequence is preceded by positional-only parameters.

  • gh-95922: Fixed bug where the compiler’s eliminate_empty_basic_blocks function ignores the last block of the code unit.

  • gh-95818: Skip over incomplete frames in PyThreadState_GetFrame().

  • gh-95876: Fix format string in _PyPegen_raise_error_known_location that can lead to memory corruption on some 64bit systems. The function was building a tuple with i (int) instead of n (Py_ssize_t) for Py_ssize_t arguments.

  • gh-95605: Fix misleading contents of error message when converting an all-whitespace string to float.

  • gh-95150: Update code object hashing and equality to consider all debugging and exception handling tables. This fixes an issue where certain non-identical code objects could be “deduplicated” during compilation.

  • gh-91146: Reduce allocation size of list from str.split() and str.rsplit(). Patch by Donghee Na and Inada Naoki.

  • gh-87092: Create a ‘jump target label’ abstraction in the compiler so that the compiler’s codegen stage does not work directly with basic blocks. This prepares the code for changes to the underlying CFG generation mechanism.

  • gh-95355: _PyPegen_Parser_New now properly detects token memory allocation errors. Patch by Honglin Zhu.

  • gh-90081: Run Python code in tracer/profiler function at full speed. Fixes slowdown in earlier versions of 3.11.

  • gh-95324: Emit a warning in debug mode if an object does not call PyObject_GC_UnTrack() before deallocation. Patch by Pablo Galindo.

  • gh-95245: Merge managed dict and values pointer into a single tagged pointer to save one word in the pre-header.

  • gh-93678: Add cfg_builder struct and refactor the relevant code so that a cfg can be constructed without an instance of the compiler struct.

  • gh-95185: Prevented crashes in the AST constructor when compiling some absurdly long expressions like "+0"*1000000. RecursionError is now raised instead. Patch by Pablo Galindo

  • gh-93351: ast.AST node positions are now validated when provided to compile() and other related functions. If invalid positions are detected, a ValueError will be raised.

  • gh-94438: Fix an issue that caused extended opcode arguments and some conditional pops to be ignored when calculating valid jump targets for assignments to the f_lineno attribute of frame objects. In some cases, this could cause inconsistent internal state, resulting in a hard crash of the interpreter.

  • gh-95060: Undocumented PyCode_Addr2Location function now properly returns when addrq argument is less than zero.

  • gh-95113: Replace all EXTENDED_ARG_QUICK instructions with basic EXTENDED_ARG instructions in unquickened code. Consumers of non-adaptive bytecode should be able to handle extended arguments the same way they were handled in CPython 3.10 and older.

  • gh-91409: Fix incorrect source location info caused by certain optimizations in the bytecode compiler.

  • gh-95023: Implement os.setns() and os.unshare() for Linux. Patch by Noam Cohen.

  • gh-94036: Fix incorrect source location info for some multi-line attribute accesses and method calls.

  • gh-94938: Fix error detection in some builtin functions when keyword argument name is an instance of a str subclass with overloaded __eq__ and __hash__. Previously it could cause SystemError or other undesired behavior.

  • gh-94996: ast.parse() will no longer parse function definitions with positional-only params when passed feature_version less than (3, 8). Patch by Shantanu Jain.

  • gh-94739: Allow jumping within, out of, and across exception handlers in the debugger.

  • gh-94949: ast.parse() will no longer parse parenthesized context managers when passed feature_version less than (3, 9). Patch by Shantanu Jain.

  • gh-94947: ast.parse() will no longer parse assignment expressions when passed feature_version less than (3, 8). Patch by Shantanu Jain.

  • gh-91256: Ensures the program name is known for help text during interpreter startup.

  • gh-94869: Fix the column offsets for some expressions in multi-line f-strings ast nodes. Patch by Pablo Galindo.

  • gh-94893: Fix an issue where frame object manipulations could corrupt inline bytecode caches.

  • gh-94822: Fix an issue where lookups of metaclass descriptors may be ignored when an identically-named attribute also exists on the class itself.

  • gh-91153: Fix an issue where a bytearray item assignment could crash if it’s resized by the new value’s __index__() method.

  • gh-90699: Fix reference counting bug in bool.__repr__(). Patch by Kumar Aditya.

  • gh-94694: Fix an issue that could cause code with multi-line method lookups to have misleading or incorrect column offset information. In some cases (when compiling a hand-built AST) this could have resulted in a hard crash of the interpreter.

  • gh-93252: Fix an issue that caused internal frames to outlive failed Python function calls, possibly resulting in memory leaks or hard interpreter crashes.

  • gh-94215: Fix an issue where exceptions raised by line-tracing events would cause frames to be left in an invalid state, possibly resulting in a hard crash of the interpreter.

  • gh-92228: Disable the compiler’s inline-small-exit-blocks optimization for exit blocks that are associated with source code lines. This fixes a bug where the debugger cannot tell where an exception handler ends and the following code block begins.

  • gh-94485: Line number of a module’s RESUME instruction is set to 0 as specified in PEP 626.

  • gh-94438: Account for instructions that can push NULL to the stack when setting line number in a frame. Prevents some (unlikely) crashes.

  • gh-91719: Reload opcode when raising unknown opcode error in the interpreter main loop, for C compilers to generate dispatching code independently.

  • gh-94329: Compile and run code with unpacking of extremely large sequences (1000s of elements). Such code failed to compile. It now compiles and runs correctly.

  • gh-94360: Fixed a tokenizer crash when reading encoded files with syntax errors from stdin with non utf-8 encoded text. Patch by Pablo Galindo

  • gh-88116: Fix an issue when reading line numbers from code objects if the encoded line numbers are close to INT_MIN. Patch by Pablo Galindo

  • gh-94262: Don’t create frame objects for incomplete frames. Prevents the creation of generators and closures from being observable to Python and C extensions, restoring the behavior of 3.10 and earlier.

  • gh-94192: Fix error for dictionary literals with invalid expression as value.

  • gh-87995: types.MappingProxyType instances are now hashable if the underlying mapping is hashable.

  • gh-93883: Revise the display strategy of traceback enhanced error locations. The indicators are only shown when the location doesn’t span the whole line.

  • gh-94163: Add BINARY_SLICE and STORE_SLICE instructions for more efficient handling and better specialization of slicing operations, where the slice is explicit in the source code.

  • gh-94021: Fix unreachable code warning in Python/specialize.c.

  • gh-93911: Specialize LOAD_ATTR for objects with custom __getattribute__.

  • gh-93955: Improve performance of attribute lookups on objects with custom __getattribute__ and __getattr__. Patch by Ken Jin.

  • gh-93911: Specialize LOAD_ATTR for property() attributes.

  • gh-93678: Refactor compiler optimisation code so that it no longer needs the struct assembler and struct compiler passed around. Instead, each function takes the CFG and other data that it actually needs. This will make it possible to test this code directly.

  • gh-93841: When built with -enable-pystats, sys._stats_on(), sys._stats_off(), sys._stats_clear() and sys._stats_dump() functions have been added to enable gathering stats for parts of programs.

  • gh-93516: Store offset of first traceable instruction in code object to avoid having to recompute it for each instruction when tracing.

  • gh-93516: Lazily create a table mapping bytecode offsets to line numbers to speed up calculation of line numbers when tracing.

  • gh-89828: types.GenericAlias no longer relays the __class__ attribute. For example, isinstance(list[int], type) no longer returns True.

  • gh-93678: Refactor the compiler to reduce boilerplate and repetition.

  • gh-93671: Fix some exponential backtrace case happening with deeply nested sequence patterns in match statements. Patch by Pablo Galindo

  • gh-93662: Make sure that the end column offsets are correct in multi-line method calls. Previously, the end column could precede the column offset.

  • gh-93461: importlib.invalidate_caches() now drops entries from sys.path_importer_cache with a relative path as name. This solves a caching issue when a process changes its current working directory.

    FileFinder no longer inserts a dot in the path, e.g. /egg/./spam is now /egg/spam.

  • gh-93621: Change order of bytecode instructions emitted for with and async with to reduce the number of entries in the exception table.

  • gh-93533: Reduce the size of the inline cache for LOAD_METHOD by 2 bytes.

  • gh-93444: Removed redundant fields from the compiler’s basicblock struct: b_nofallthrough, b_exit, b_return. They can be easily calculated from the opcode of the last instruction of the block.

  • gh-93429: LOAD_METHOD instruction has been removed. It was merged back into LOAD_ATTR.

  • gh-93418: Fixed an assert where an f-string has an equal sign ‘=’ following an expression, but there’s no trailing brace. For example, f”{i=”.

  • gh-93382: Cache the result of PyCode_GetCode() function to restore the O(1) lookup of the co_code attribute.

  • gh-93359: Ensure that custom ast nodes without explicit end positions can be compiled. Patch by Pablo Galindo.

  • gh-93356: Code for exception handlers is emitted at the end of the code unit’s bytecode. This avoids one jump when no exception is raised.

  • gh-93354: Use exponential backoff for specialization counters in the interpreter. Can reduce the number of failed specializations significantly and avoid slowdown for those parts of a program that are not suitable for specialization.

  • gh-93283: Improve error message for invalid syntax of conversion character in f-string expressions.

  • gh-93345: Fix a crash in substitution of a TypeVar in nested generic alias after TypeVarTuple.

  • gh-93223: When a bytecode instruction jumps to an unconditional jump instruction, the first instruction can often be optimized to target the unconditional jump’s target directly. For tracing reasons, this would previously only occur if both instructions have the same line number. This also now occurs if the unconditional jump is artificial, i.e., if it has no associated line number.

  • gh-84694: The --experimental-isolated-subinterpreters configure option and EXPERIMENTAL_ISOLATED_SUBINTERPRETERS macro have been removed.

  • gh-91924: Fix __lltrace__ debug feature if the stdout encoding is not UTF-8. Patch by Victor Stinner.

  • gh-93040: Wraps unused parameters in Objects/obmalloc.c with Py_UNUSED.

  • gh-93143: Avoid NULL checks for uninitialized local variables by determining at compile time which variables must be initialized.

  • gh-93061: Backward jumps after async for loops are no longer given dubious line numbers.

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

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

  • gh-93012: Added the new function PyType_FromMetaclass(), which generalizes the existing PyType_FromModuleAndSpec() using an additional metaclass argument. This is useful for language binding tools, where it can be used to intercept type-related operations like subclassing or static attribute access by specifying a metaclass with custom slots.

    Importantly, PyType_FromMetaclass() is available in the Limited API, which provides a path towards migrating more binding tools onto the Stable ABI.

  • gh-93021: Fix the __text_signature__ for __get__() methods implemented in C. Patch by Jelle Zijlstra.

  • gh-89914: The operand of the YIELD_VALUE instruction is set to the stack depth. This is done to help frame handling on yield and may assist debuggers.

  • gh-92955: Fix memory leak in code object’s lines and positions iterators as they were not finalized at exit. Patch by Kumar Aditya.

  • gh-92930: Fixed a crash in _pickle.c from mutating collections during __reduce__ or persistent_id.

  • gh-90690: The PRECALL instruction has been removed. It offered only a small advantage for specialization and is not needed in the vast majority of cases.

  • gh-92914: Always round the allocated size for lists up to the nearest even number.

  • gh-92858: Improve error message for some suites with syntax error before ‘:’

  • gh-90473: Decrease default recursion limit on WASI to address limited call stack size.

  • gh-92804: Fix memory leak in memoryview iterator as it was not finalized at exit. Patch by Kumar Aditya.

  • gh-92777: Specialize LOAD_METHOD for objects with lazy dictionaries. Patch by Ken Jin.

  • gh-92658: Add support for connecting and binding to Hyper-V sockets on Windows Hyper-V hosts and guests.

  • gh-92236: Remove spurious “LINE” event when starting a generator or coroutine, visible tracing functions implemented in C.

  • gh-91102: _warnings.warn_explicit() is ported to Argument Clinic.

  • gh-92619: Make the compiler duplicate an exit block only if none of its instructions have a lineno (previously only the first instruction in the block was checked, leading to unnecessarily duplicated blocks).

  • gh-88750: The deprecated debug build only PYTHONTHREADDEBUG environment variable no longer does anything.

  • gh-92261: Fix hang when trying to iterate over a typing.Union.

  • gh-91432: Specialized the FOR_ITER opcode using the PEP 659 machinery

  • gh-91399: Removed duplicate ‘{0, 0, 0, 0, 0, 0}’ entry in ‘Objects/unicodetype_db.h’.

  • gh-91578: Updates the error message for abstract class.

  • bpo-47091: Improve performance of repetition of list and tuple by using memcpy to copy data and performing the reference increments in one step.

  • bpo-46142: Make --help output shorter by moving some info to the new --help-env and --help-xoptions command-line options. Also add --help-all option to print complete usage.

  • bpo-42316: Document some places where an assignment expression needs parentheses.

Library

  • gh-89237: Fix hang on Windows in subprocess.wait_closed() in asyncio with ProactorEventLoop. Patch by Kumar Aditya.

  • gh-97928: tkinter.Text.count() raises now an exception for options starting with “-” instead of silently ignoring them.

  • gh-98393: The os module no longer accepts bytes-like paths, like bytearray and memoryview types: only the exact bytes type is accepted for bytes strings. Patch by Victor Stinner.

  • gh-98363: Added itertools.batched() to batch data into lists of a given length with the last list possibly being shorter than the others.

  • gh-98331: Update the bundled copies of pip and setuptools to versions 22.3 and 65.5.0 respectively.

  • gh-98307: A createSocket() method was added to SysLogHandler.

  • gh-96035: Fix bug in urllib.parse.urlparse() that causes certain port numbers containing whitespace, underscores, plus and minus signs, or non-ASCII digits to be incorrectly accepted.

  • gh-98257: Make sys.setprofile() and sys.settrace() functions reentrant. They can no long fail with: RuntimeError("Cannot install a trace function while another trace function is being installed"). Patch by Victor Stinner.

  • gh-98251: Allow venv to pass along PYTHON* variables to ensurepip and pip when they do not impact path resolution

  • gh-94597: Deprecated asyncio.AbstractEventLoopPolicy.get_child_watcher() and asyncio.AbstractEventLoopPolicy.set_child_watcher() methods to be removed in Python 3.14. Patch by Kumar Aditya.

  • gh-98178: On macOS, fix a crash in syslog.syslog() in multi-threaded applications. On macOS, the libc syslog() function is not thread-safe, so syslog.syslog() no longer releases the GIL to call it. Patch by Victor Stinner.

  • gh-44098: Release the GIL when creating mmap.mmap objects on Unix.

  • gh-87730: Wrap network errors consistently in urllib FTP support, so the test suite doesn’t fail when a network is available but the public internet is not reachable.

  • gh-94597: The child watcher classes MultiLoopChildWatcher, FastChildWatcher and SafeChildWatcher are deprecated and will be removed in Python 3.14. Patch by Kumar Aditya.

  • gh-98023: Change default child watcher to PidfdChildWatcher on Linux systems which supports it. Patch by Kumar Aditya.

  • gh-90985: Earlier in 3.11 we deprecated asyncio.Task.cancel("message"). We realized we were too harsh, and have undeprecated it.

  • gh-65961: Do not rely solely on __cached__ on modules; code will also support __spec__.cached.

  • gh-97646: Replace deprecated application/javascript with text/javascript in mimetypes. See RFC 9239. Patch by Noam Cohen.

  • gh-97930: Apply changes from importlib_resources 5.8 and 5.9: Traversable.joinpath provides a concrete implementation. as_file now supports directories of resources.

  • gh-97850: Remove deprecated importlib.util.set_loader() and importlib.util.module_for_loader() from importlib.util.

  • gh-97837: Change deprecate warning message in unittest from

    It is deprecated to return a value!=None

    to

    It is deprecated to return a value that is not None from a test case

  • gh-97825: Fixes AttributeError when subprocess.check_output() is used with argument input=None and either of the arguments encoding or errors are used.

  • gh-97008: NameError and AttributeError spelling suggestions provided since gh-82711 are now also emitted by the pure Python traceback module. Tests for those suggestions now exercise both implementations to ensure they are equivalent. Patch by Carl Friedrich Bolz-Tereick and Łukasz Langa.

  • gh-97799: dataclass now uses inspect.get_annotations() to examine the annotations on class objects.

  • gh-97781: Removed deprecated interfaces in importlib.metadata (entry points accessed as dictionary, implicit dictionary construction of sequence of EntryPoint objects, mutablility of EntryPoints result, access of entry point by index). entry_points now has a simpler, more straightforward API (returning EntryPoints).

  • gh-96827: Avoid spurious tracebacks from asyncio when default executor cleanup is delayed until after the event loop is closed (e.g. as the result of a keyboard interrupt).

  • gh-95534: gzip.GzipFile.read() reads 10% faster.

  • gh-97592: Avoid a crash in the C version of asyncio.Future.remove_done_callback() when an evil argument is passed.

  • gh-97639: Remove tokenize.NL check from tabnanny.

  • gh-97545: Make Semaphore run faster.

  • gh-73588: Fix generation of the default name of tkinter.Checkbutton. Previously, checkbuttons in different parent widgets could have the same short name and share the same state if arguments “name” and “variable” are not specified. Now they are globally unique.

  • gh-96865: fix Flag to use boundary CONFORM

    This restores previous Flag behavior of allowing flags with non-sequential values to be combined; e.g.

    class Skip(Flag): TWO = 2 EIGHT = 8

    Skip.TWO | Skip.EIGHT -> <Skip.TWO|EIGHT: 10>

  • gh-97005: Update bundled libexpat to 2.4.9

  • gh-85760: Fix race condition in asyncio where process_exited() called before the pipe_data_received() leading to inconsistent output. Patch by Kumar Aditya.

  • gh-96704: Pass the correct contextvars.Context when a asyncio exception handler is called on behalf of a task or callback handle. This adds a new Task method, get_context, and also a new Handle method with the same name. If this method is not found on a task object (perhaps because it is a third-party library that does not yet provide this method), the context prevailing at the time the exception handler is called is used.

  • gh-96819: Fixed check in multiprocessing.resource_tracker that guarantees that the length of a write to a pipe is not greater than PIPE_BUF.

  • gh-95865: Reduce urllib.parse.quote_from_bytes() memory use on large values.

    Contributed by Dennis Sweeney.

  • gh-96741: Corrected type annotation for dataclass attribute pstats.FunctionProfile.ncalls to be str.

  • gh-96734: Update unicodedata database to Unicode 15.0.0.

  • gh-96735: Fix undefined behaviour in struct.unpack().

  • gh-46412: Improve performance of bool(db) for large ndb/gdb databases. Previously this would call len(db) which would iterate over all keys – the answer (empty or not) is known after the first key.

  • gh-96652: Fix the faulthandler implementation of faulthandler.register(signal, chain=True) if the sigaction() function is not available: don’t call the previous signal handler if it’s NULL. Patch by Victor Stinner.

  • gh-68163: Correct conversion of numbers.Rational’s to float.

  • gh-96538: Speed up bisect.bisect() functions by taking advantage of type-stability.

  • gh-96465: Fraction hashes are now cached.

  • gh-96079: In typing, fix missing field name and incorrect __module__ in _AnnotatedAlias.

  • gh-96415: Remove types._cell_factory from module namespace.

  • gh-95987: Fix repr of Any subclasses.

  • gh-96388: Work around missing socket functions in socket’s __repr__.

  • gh-96385: Fix TypeVarTuple.__typing_prepare_subst__. TypeError was not raised when using more than one TypeVarTuple, like [*T, *V] in type alias substitutions.

  • gh-96142: Add match_args, kw_only, slots, and weakref_slot to _DataclassParams.

  • gh-96073: In inspect, fix overeager replacement of “typing.” in formatting annotations.

  • gh-89258: Added a getChildren() method to logging.Logger, to get the immediate child loggers of a logger.

  • gh-96346: Use double caching for compiled RE patterns.

  • gh-96349: Fixed a minor performance regression in threading.Event.__init__()

  • gh-90467: Fix asyncio.streams.StreamReaderProtocol to keep a strong reference to the created task, so that it’s not garbage collected

  • gh-96172: Fix a bug in unicodedata: east_asian_width used to return the wrong value for unassigned characters; and for yet unassigned, but reserved characters.

  • gh-96159: Fix a performance regression in logging TimedRotatingFileHandler. Only check for special files when the rollover time has passed.

  • gh-96175: Fix unused localName parameter in the Attr class in xml.dom.minidom.

  • gh-96145: Add AttrDict to JSON module for use with object_hook.

  • gh-96052: Fix handling compiler warnings (SyntaxWarning and DeprecationWarning) in codeop.compile_command() when checking for incomplete input. Previously it emitted warnings and raised a SyntaxError. Now it always returns None for incomplete input without emitting any warnings.

  • gh-96125: Fix incorrect condition that causes sys.thread_info.name to be wrong on pthread platforms.

  • gh-96019: Fix a bug in the makeunicodedata.py script leading to about 13 KiB of space saving in the unicodedata module, specifically the character decomposition data.

  • gh-95463: Remove an incompatible change from bpo-28080 that caused a regression that ignored the utf8 in ZipInfo.flag_bits. Patch by Pablo Galindo.

  • gh-69142: Add %:z strftime format code (generates tzoffset with colons as separator), see strftime() and strptime() Behavior.

  • gh-95899: Fix asyncio.Runner to call asyncio.set_event_loop() only once to avoid calling attach_loop() multiple times on child watchers. Patch by Kumar Aditya.

  • gh-95736: Fix unittest.IsolatedAsyncioTestCase to set event loop before calling setup functions. Patch by Kumar Aditya.

  • gh-95865: Speed up urllib.parse.quote_from_bytes() by replacing a list comprehension with map().

  • gh-95861: Add support for computing Spearman’s correlation coefficient to the existing statistics.correlation() function.

  • gh-95804: Fix logging shutdown handler so it respects MemoryHandler.flushOnClose.

  • gh-95704: When a task catches asyncio.CancelledError and raises some other error, the other error should generally not silently be suppressed.

  • gh-95149: The HTTPStatus enum offers a couple of properties to indicate the HTTP status category e.g. HTTPStatus.OK.is_success.

  • gh-95609: Update bundled pip to 22.2.2.

  • gh-95289: Fix asyncio.TaskGroup to propagate exception when asyncio.CancelledError was replaced with another exception by a context manger. Patch by Kumar Aditya and Guido van Rossum.

  • gh-94909: Fix incorrect joining of relative Windows paths with drives in pathlib.PurePath initializer.

  • gh-95385: Faster json.dumps() when sorting of keys is not requested (default).

  • gh-83901: Improve Signature.bind error message for missing keyword-only arguments.

  • gh-95339: Update bundled pip to 22.2.1.

  • gh-95045: Fix GC crash when deallocating _lsprof.Profiler by untracking it before calling any callbacks. Patch by Kumar Aditya.

  • gh-95231: Fail gracefully if EPERM or ENOSYS is raised when loading crypt methods. This may happen when trying to load MD5 on a Linux kernel with FIPS enabled.

  • gh-95097: Fix asyncio.run() for asyncio.Task implementations without uncancel() method. Patch by Kumar Aditya.

  • gh-95087: Fix IndexError in parsing invalid date in the email module.

  • gh-95199: Upgrade bundled setuptools to 63.2.0.

  • gh-95194: Upgrade bundled pip to 22.2.

  • gh-93899: Fix check for existence of os.EFD_CLOEXEC, os.EFD_NONBLOCK and os.EFD_SEMAPHORE flags on older kernel versions where these flags are not present. Patch by Kumar Aditya.

  • gh-95166: Fix concurrent.futures.Executor.map() to cancel the currently waiting on future on an error - e.g. TimeoutError or KeyboardInterrupt.

  • gh-95132: Fix a sqlite3 regression where *args and **kwds were incorrectly relayed from connect() to the Connection factory. The regression was introduced in 3.11a1 with PR 24421 (gh-85128). Patch by Erlend E. Aasland.`

  • gh-93157: Fix fileinput module didn’t support errors option when inplace is true.

  • gh-91212: Fixed flickering of the turtle window when the tracer is turned off. Patch by Shin-myoung-serp.

  • gh-95077: Add deprecation warning for enum member.member access (e.g. Color.RED.BLUE). Remove EnumMeta.__getattr__.

  • gh-95109: Ensure that timeouts scheduled with asyncio.Timeout that have already expired are delivered promptly.

  • gh-95105: wsgiref.types.InputStream.__iter__() should return Iterator[bytes], not Iterable[bytes]. Patch by Shantanu Jain.

  • gh-95066: Replaced assert with exception in ast.parse(), when feature_version has an invalid major version. Patch by Shantanu Jain.

  • gh-77617: Add sqlite3 command-line interface. Patch by Erlend Aasland.

  • gh-95005: Replace _PyAccu with _PyUnicodeWriter in JSON encoder and StringIO and remove the _PyAccu implementation.

  • gh-90085: Remove -c/--clock and -t/--time CLI options of timeit. The options had been deprecated since Python 3.3 and the functionality was removed in Python 3.7. Patch by Shantanu Jain.

  • gh-94857: Fix refleak in _io.TextIOWrapper.reconfigure. Patch by Kumar Aditya.

  • gh-94821: Fix binding of unix socket to empty address on Linux to use an available address from the abstract namespace, instead of “0”.

  • gh-94736: Fix crash when deallocating an instance of a subclass of _multiprocessing.SemLock. Patch by Kumar Aditya.

  • gh-81620: Add random.binomialvariate().

  • gh-74116: Allow asyncio.StreamWriter.drain() to be awaited concurrently by multiple tasks. Patch by Kumar Aditya.

  • gh-87822: When called with capture_locals=True, the traceback module functions swallow exceptions raised from calls to repr() on local variables of frames. This is in order to prioritize the original exception over rendering errors. An indication of the failure is printed in place of the missing value. (Patch by Simon-Martin Schroeder).

  • gh-88050: Fix asyncio subprocess transport to kill process cleanly when process is blocked and avoid RuntimeError when loop is closed. Patch by Kumar Aditya.

  • gh-94637: SSLContext.set_default_verify_paths() now releases the GIL around SSL_CTX_set_default_verify_paths call. The function call performs I/O and CPU intensive work.

  • gh-94309: Deprecate aliases typing.Hashable and typing.Sized

  • gh-92546: An undocumented python -m pprint benchmark is moved into pprint suite of pyperformance. Patch by Oleg Iarygin.

  • gh-94607: Fix subclassing complex generics with type variables in typing. Previously an error message saying Some type variables ... are not listed in Generic[...] was shown. typing no longer populates __parameters__ with the __parameters__ of a Python class.

  • gh-94619: Remove the long-deprecated module_repr() from importlib.

  • gh-93910: The ability to access the other values of an enum on an enum (e.g. Color.RED.BLUE) has been restored in order to fix a performance regression.

  • gh-93896: Fix asyncio.run() and unittest.IsolatedAsyncioTestCase to always the set event loop as it was done in Python 3.10 and earlier. Patch by Kumar Aditya.

  • gh-94343: Allow setting the attributes of reprlib.Repr during object initialization

  • gh-94382: Port static types of _multiprocessing module to heap types. Patch by Kumar Aditya.

  • gh-78724: Fix crash in struct.Struct when it was not completely initialized by initializing it in __new__`(). Patch by Kumar Aditya.

  • gh-94510: Re-entrant calls to sys.setprofile() and sys.settrace() now raise RuntimeError. Patch by Pablo Galindo.

  • gh-92336: Fix bug where linecache.getline() fails on bad files with UnicodeDecodeError or SyntaxError. It now returns an empty string as per the documentation.

  • gh-94398: Once a asyncio.TaskGroup has started shutting down (i.e., at least one task has failed and the task group has started cancelling the remaining tasks), it should not be possible to add new tasks to the task group.

  • gh-94383: xml.etree: Remove the ElementTree.Element.copy() method of the pure Python implementation, deprecated in Python 3.10, use the copy.copy() function instead. The C implementation of xml.etree has no copy() method, only a __copy__() method. Patch by Victor Stinner.

  • gh-94379: zipimport: Remove find_loader() and find_module() methods, deprecated in Python 3.10: use the find_spec() method instead. See PEP 451 for the rationale. Patch by Victor Stinner.

  • gh-94352: shlex.split(): Passing None for s argument now raises an exception, rather than reading sys.stdin. The feature was deprecated in Python 3.9. Patch by Victor Stinner.

  • gh-94318: Strip trailing spaces in pydoc text output.

  • gh-89988: Fix memory leak in pickle.Pickler when looking up dispatch_table. Patch by Kumar Aditya.

  • gh-90016: Deprecate sqlite3 default adapters and converters. Patch by Erlend E. Aasland.

  • gh-94254: Fixed types of struct module to be immutable. Patch by Kumar Aditya.

  • gh-93259: Now raise ValueError when None or an empty string are passed to Distribution.from_name (and other callers).

  • gh-74696: shutil.make_archive() now passes the root_dir argument to custom archivers which support it.

  • gh-94216: The dis module now has the opcodes for pseudo instructions (those which are used by the compiler during code generation but then removed or replaced by real opcodes before the final bytecode is emitted).

  • gh-93096: Removed undocumented python -m codecs. Use python -m unittest test.test_codecs.EncodedFileTest instead.

  • gh-94207: Made _struct.Struct GC-tracked in order to fix a reference leak in the _struct module.

  • gh-93096: Removed undocumented -t argument of python -m base64. Use python -m unittest test.test_base64.LegacyBase64TestCase.test_encodebytes instead.

  • gh-94226: Remove the locale.format() function, deprecated in Python 3.7: use locale.format_string() instead. Patch by Victor Stinner.

  • gh-94199: Remove the ssl.match_hostname() function. The ssl.match_hostname() was deprecated in Python 3.7. OpenSSL performs hostname matching since Python 3.7, Python no longer uses the ssl.match_hostname() function. Patch by Victor Stinner.

  • gh-94214: Document the context object used in the venv.EnvBuilder class, and add the new environment’s library path to it.

  • gh-94199: Remove the ssl.wrap_socket() function, deprecated in Python 3.7: instead, create a ssl.SSLContext object and call its ssl.SSLContext.wrap_socket method. Any package that still uses ssl.wrap_socket() is broken and insecure. The function neither sends a SNI TLS extension nor validates server hostname. Code is subject to CWE-295: Improper Certificate Validation. Patch by Victor Stinner.

  • gh-94199: Remove the ssl.RAND_pseudo_bytes() function, deprecated in Python 3.6: use os.urandom() or ssl.RAND_bytes() instead. Patch by Victor Stinner.

  • gh-94199: hashlib: Remove the pure Python implementation of hashlib.pbkdf2_hmac(), deprecated in Python 3.10. Python 3.10 and newer requires OpenSSL 1.1.1 (PEP 644): this OpenSSL version provides a C implementation of pbkdf2_hmac() which is faster. Patch by Victor Stinner.

  • gh-94196: gzip: Remove the filename attribute of gzip.GzipFile, deprecated since Python 2.6, use the name attribute instead. In write mode, the filename attribute added '.gz' file extension if it was not present. Patch by Victor Stinner.

  • gh-94182: run the asyncio.PidfdChildWatcher on the running loop, this allows event loops to run subprocesses when there is no default event loop running on the main thread

  • gh-94169: Remove io.OpenWrapper and _pyio.OpenWrapper, deprecated in Python 3.10: just use open() instead. The open() (io.open()) function is a built-in function. Since Python 3.10, _pyio.open() is also a static method. Patch by Victor Stinner.

  • gh-91742: Fix pdb crash after jump caused by a null pointer dereference. Patch by Kumar Aditya.

  • gh-94101: Manual instantiation of ssl.SSLSession objects is no longer allowed as it lead to misconfigured instances that crashed the interpreter when attributes where accessed on them.

  • gh-84753: inspect.iscoroutinefunction(), inspect.isgeneratorfunction(), and inspect.isasyncgenfunction() now properly return True for duck-typed function-like objects like instances of unittest.mock.AsyncMock.

    This makes inspect.iscoroutinefunction() consistent with the behavior of asyncio.iscoroutinefunction(). Patch by Mehdi ABAAKOUK.

  • gh-94028: Fix a regression in the sqlite3 where statement objects were not properly cleared and reset after use in cursor iters. The regression was introduced by PR 27884 in Python 3.11a1. Patch by Erlend E. Aasland.

  • gh-93973: Add keyword argument all_errors to asyncio.create_connection so that multiple connection errors can be raised as an ExceptionGroup.

  • gh-93963: Officially deprecate from importlib.abc classes moved to importlib.resources.abc.

  • gh-93858: Prevent error when activating venv in nested fish instances.

  • gh-93820: Pickle enum.Flag by name.

  • gh-93847: Fix repr of enum of generic aliases.

  • gh-91404: Revert the re memory leak when a match is terminated by a signal or memory allocation failure as the implemented fix caused a major performance regression.

  • gh-83499: Fix double closing of file description in tempfile.

  • gh-93820: Fixed a regression when copy.copy()-ing enum.Flag with multiple flag members.

  • gh-79512: Fixed names and __module__ value of weakref classes ReferenceType, ProxyType, CallableProxyType. It makes them pickleable.

  • gh-91389: Fix an issue where dis utilities could report missing or incorrect position information in the presence of CACHE entries.

  • gh-93626: Set __future__.annotations to have a None mandatoryRelease to indicate that it is currently ‘TBD’.

  • gh-90473: Emscripten and WASI have no home directory and cannot provide PEP 370 user site directory.

  • gh-90494: copy.copy() and copy.deepcopy() now always raise a TypeError if __reduce__() returns a tuple with length 6 instead of silently ignore the 6th item or produce incorrect result.

  • gh-90549: Fix a multiprocessing bug where a global named resource (such as a semaphore) could leak when a child process is spawned (as opposed to forked).

  • gh-93521: Fixed a case where dataclasses would try to add __weakref__ into the __slots__ for a dataclass that specified weakref_slot=True when it was already defined in one of its bases. This resulted in a TypeError upon the new class being created.

  • gh-79579: sqlite3 now correctly detects DML queries with leading comments. Patch by Erlend E. Aasland.

  • gh-93421: Update sqlite3.Cursor.rowcount when a DML statement has run to completion. This fixes the row count for SQL queries like UPDATE ... RETURNING. Patch by Erlend E. Aasland.

  • gh-93475: Expose FICLONE and FICLONERANGE constants in fcntl. Patch by Illia Volochii.

  • gh-93370: Deprecate sqlite3.version and sqlite3.version_info.

  • gh-91810: Suppress writing an XML declaration in open files in ElementTree.write() with encoding='unicode' and xml_declaration=None.

  • gh-91162: Support splitting of unpacked arbitrary-length tuple over TypeVar and TypeVarTuple parameters. For example:

    • A[T, *Ts][*tuple[int, ...]] -> A[int, *tuple[int, ...]]

    • A[*Ts, T][*tuple[int, ...]] -> A[*tuple[int, ...], int]

  • gh-93353: Fix the importlib.resources.as_file() context manager to remove the temporary file if destroyed late during Python finalization: keep a local reference to the os.remove() function. Patch by Victor Stinner.

  • gh-83658: Make multiprocessing.Pool raise an exception if maxtasksperchild is not None or a positive int.

  • gh-93312: Add os.PIDFD_NONBLOCK flag to open a file descriptor for a process with os.pidfd_open() in non-blocking mode. Patch by Kumar Aditya.

  • gh-88123: Implement Enum __contains__ that returns True or False to replace the deprecated behaviour that would sometimes raise a TypeError.

  • gh-93297: Make asyncio task groups prevent child tasks from being GCed

  • gh-85308: Changed argparse.ArgumentParser to use filesystem encoding and error handler instead of default text encoding to read arguments from file (e.g. fromfile_prefix_chars option). This change affects Windows; argument file should be encoded with UTF-8 instead of ANSI Codepage.

  • gh-93156: Accessing the pathlib.PurePath.parents sequence of an absolute path using negative index values produced incorrect results.

  • gh-93162: Add the ability for logging.config.dictConfig() to usefully configure QueueHandler and QueueListener as a pair, and add logging.getHandlerByName() and logging.getHandlerNames() APIs to allow access to handlers by name.

  • gh-93243: The smtpd module was removed per the schedule in PEP 594.

  • gh-92886: Replace assert statements with raise AssertionError() in BaseHandler so that the tested behaviour is maintained running with optimizations (-O).

  • gh-90155: Fix broken asyncio.Semaphore when acquire is cancelled.

  • gh-90817: The locale.resetlocale() function is deprecated and will be removed in Python 3.13. Use locale.setlocale(locale.LC_ALL, "") instead. Patch by Victor Stinner.

  • gh-91513: Added taskName attribute to logging module for use with asyncio tasks.

  • gh-74696: shutil.make_archive() no longer temporarily changes the current working directory during creation of standard .zip or tar archives.

  • gh-92728: The re.template() function and the corresponding re.TEMPLATE and re.T flags are restored after they were removed in 3.11.0b1, but they are now deprecated, so they might be removed from Python 3.13.

  • gh-93033: Search in some strings (platform dependent i.e [U+0xFFFF, U+0x0100] on Windows or [U+0xFFFFFFFF, U+0x00010000] on Linux 64-bit) are now up to 10 times faster.

  • gh-89973: Fix re.error raised in fnmatch if the pattern contains a character range with upper bound lower than lower bound (e.g. [c-a]). Now such ranges are interpreted as empty ranges.

  • gh-93044: No longer convert the database argument of sqlite3.connect() to bytes before passing it to the factory.

  • gh-93010: In a very special case, the email package tried to append the nonexistent InvalidHeaderError to the defect list. It should have been InvalidHeaderDefect.

  • gh-92986: Fix ast.unparse() when ImportFrom.level is None

  • gh-92932: Now dis() and get_instructions() handle operand values for instructions prefixed by EXTENDED_ARG_QUICK. Patch by Sam Gross and Donghee Na.

  • gh-92675: Fix venv.ensure_directories() to accept pathlib.Path arguments in addition to str paths. Patch by David Foster.

  • gh-87901: Removed the encoding argument from os.popen() that was added in 3.11b1.

  • gh-91922: Fix function sqlite.connect() and the sqlite.Connection constructor on non-UTF-8 locales. Also, they now support bytes paths non-decodable with the current FS encoding.

  • gh-92869: Added c_time_t to ctypes, which has the same size as the time_t type in C.

  • gh-92839: Fixed crash resulting from calling bisect.insort() or bisect.insort_left() with the key argument not equal to None.

  • gh-90473: subprocess now fails early on Emscripten and WASI platforms to work around missing os.pipe() on WASI.

  • gh-89325: Removed many old deprecated unittest features: TestCase method aliases, undocumented and broken TestCase method assertDictContainsSubset, undocumented TestLoader.loadTestsFromModule parameter use_load_tests, and an underscored alias of the TextTestResult class.

  • gh-92734: Allow multi-element reprs emitted by reprlib to be pretty-printed using configurable indentation.

  • gh-92671: Fixed ast.unparse() for empty tuples in the assignment target context.

  • gh-91581: utcfromtimestamp() no longer attempts to resolve fold in the pure Python implementation, since the fold is never 1 in UTC. In addition to being slightly faster in the common case, this also prevents some errors when the timestamp is close to datetime.min. Patch by Paul Ganssle.

  • gh-86388: Removed randrange() functionality deprecated since Python 3.10. Formerly, randrange(10.0) losslessly converted to randrange(10). Now, it raises a TypeError. Also, the exception raised for non-integral values such as randrange(10.5) or randrange(‘10’) has been changed from ValueError to TypeError.

  • gh-90385: Add pathlib.Path.walk() as an alternative to os.walk().

  • gh-92550: Fix pathlib.Path.rglob() for empty pattern.

  • gh-92591: Allow logging filters to return a logging.LogRecord instance so that filters attached to logging.Handlers can enrich records without side effects on other handlers.

  • gh-92445: Fix a bug in argparse where nargs="*" would raise an error instead of returning an empty list when 0 arguments were supplied if choice was also defined in parser.add_argument.

  • gh-92547: Remove undocumented sqlite3 features deprecated in Python 3.10:

    • sqlite3.enable_shared_cache()

    • sqlite3.OptimizedUnicode

    Patch by Erlend E. Aasland.

  • gh-92530: Fix an issue that occurred after interrupting threading.Condition.notify().

  • gh-92531: The statistics.median_grouped() function now always return a float. Formerly, it did not convert the input type when for sequences of length one.

  • gh-84131: The pathlib.Path deprecated method link_to has been removed. Use 3.10’s hardlink_to() method instead as its semantics are consistent with that of symlink_to().

  • gh-89336: Removed configparser module APIs: the SafeConfigParser class alias, the ParsingError.filename property and parameter, and the ConfigParser.readfp method, all of which were deprecated since Python 3.2.

  • gh-92391: Add __class_getitem__() to csv.DictReader and csv.DictWriter, allowing them to be parameterized at runtime. Patch by Marc Mueller.

  • gh-91968: Add SO_RTABLE and SO_USER_COOKIE constants to socket.

  • gh-91810: ElementTree method write() and function tostring() now use the text file’s encoding (“UTF-8” if not available) instead of locale encoding in XML declaration when encoding="unicode" is specified.

  • gh-81790: os.path.splitdrive() now understands DOS device paths with UNC links (beginning \\?\UNC\). Contributed by Barney Gale.

  • gh-91760: Apply more strict rules for numerical group references and group names in regular expressions. Only sequence of ASCII digits is now accepted as a numerical reference. The group name in bytes patterns and replacement strings can now only contain ASCII letters and digits and underscore.

  • gh-90622: Worker processes for concurrent.futures.ProcessPoolExecutor are no longer spawned on demand (a feature added in 3.9) when the multiprocessing context start method is "fork" as that can lead to deadlocks in the child processes due to a fork happening while threads are running.

  • gh-91577: Move imports in SharedMemory methods to module level so that they can be executed late in python finalization.

  • gh-91581: Remove an unhandled error case in the C implementation of calls to datetime.fromtimestamp with no time zone (i.e. getting a local time from an epoch timestamp). This should have no user-facing effect other than giving a possibly more accurate error message when called with timestamps that fall on 10000-01-01 in the local time. Patch by Paul Ganssle.

  • gh-91539: Improve performance of urllib.request.getproxies_environment when there are many environment variables

  • gh-91524: Speed up the regular expression substitution (functions re.sub() and re.subn() and corresponding re.Pattern methods) for replacement strings containing group references by 2–3 times.

  • gh-91447: Fix findtext in the xml module to only give an empty string when the text attribute is set to None.

  • gh-91456: Deprecate current default auto() behavior: In 3.13 the default will be for for auto() to always return the largest member value incremented by 1, and to raise if incompatible value types are used.

  • bpo-47231: Fixed an issue with inconsistent trailing slashes in tarfile longname directories.

  • bpo-39064: zipfile.ZipFile now raises zipfile.BadZipFile instead of ValueError when reading a corrupt zip file in which the central directory offset is negative.

  • bpo-41287: Fix handling of the doc argument in subclasses of property().

  • gh-90005: ctypes dependency libffi is now detected with pkg-config.

  • bpo-32547: The constructors for DictWriter and DictReader now coerce the fieldnames argument to a list if it is an iterator.

  • bpo-35540: Fix dataclasses.asdict() crash when collections.defaultdict is present in the attributes.

  • bpo-47063: Add an index_pages parameter to support using non-default index page names.

  • bpo-47025: Drop support for bytes on sys.path.

  • bpo-46951: Order the contents of zipapp archives, to make builds more reproducible.

  • bpo-42777: Implement pathlib.Path.is_mount() for Windows paths.

  • bpo-46755: In QueueHandler, clear stack_info from LogRecord to prevent stack trace from being written twice.

  • bpo-45393: Fix the formatting for await x and not x in the operator precedence table when using the help() system.

  • bpo-46642: Improve error message when trying to subclass an instance of typing.TypeVar, typing.ParamSpec, typing.TypeVarTuple, etc. Based on patch by Gregory Beauregard.

  • bpo-46364: Restrict use of sockets instead of pipes for stdin of subprocesses created by asyncio to AIX platform only.

  • bpo-28249: Set doctest.DocTest.lineno to None when object does not have __doc__.

  • bpo-46197: Fix ensurepip environment isolation for subprocess running pip.

  • bpo-45924: Fix asyncio incorrect traceback when future’s exception is raised multiple times. Patch by Kumar Aditya.

  • bpo-45046: Add support of context managers in unittest: methods enterContext() and enterClassContext() of class TestCase, method enterAsyncContext() of class IsolatedAsyncioTestCase and function unittest.enterModuleContext().

  • bpo-44173: Enable fast seeking of uncompressed unencrypted zipfile.ZipExtFile

  • bpo-42627: Fix incorrect parsing of Windows registry proxy settings

  • bpo-42047: Add threading.get_native_id() support for DragonFly BSD. Patch by David Carlier.

  • bpo-14243: The tempfile.NamedTemporaryFile function has a new optional parameter delete_on_close

  • bpo-41246: Give the same callback function for when the overlapped operation is done to the functions recv, recv_into, recvfrom, sendto, send and sendfile inside IocpProactor.

  • bpo-39264: Fixed collections.UserDict.get() to not call __missing__() when a value is not found. This matches the behavior of dict. Patch by Bar Harel.

  • bpo-38693: importlib now uses f-strings internally instead of str.format.

  • bpo-38267: Add timeout parameter to asyncio.loop.shutdown_default_executor(). The default value is None, which means the executor will be given an unlimited amount of time. When called from asyncio.Runner or asyncio.run(), the default timeout is 5 minutes.

  • bpo-34828: sqlite3.Connection.iterdump() now handles databases that use AUTOINCREMENT in one or more tables.

  • bpo-32990: Support reading wave files with the WAVE_FORMAT_EXTENSIBLE format in the wave module.

  • bpo-26253: Allow adjustable compression level for tarfile streams in tarfile.open().

Documentation

  • gh-85525: Remove extra row

  • gh-86404: Deprecated tools make suspicious and rstlint.py are now removed. They have been replaced by spinx-lint.

  • gh-97741: Fix ! in c domain ref target syntax via a conf.py patch, so it works as intended to disable ref target resolution.

  • gh-96432: Fraction literals now support whitespace around the forward slash, Fraction('2 / 3').

  • gh-96098: Improve discoverability of the higher level concurrent.futures module by providing clearer links from the lower level threading and multiprocessing modules.

  • gh-95957: What’s New 3.11 now has instructions for how to provide compiler and linker flags for Tcl/Tk and OpenSSL on RHEL 7 and CentOS 7.

  • gh-95588: Clarified the conflicting advice given in the ast documentation about ast.literal_eval() being “safe” for use on untrusted input while at the same time warning that it can crash the process. The latter statement is true and is deemed unfixable without a large amount of work unsuitable for a bugfix. So we keep the warning and no longer claim that literal_eval is safe.

  • gh-91207: Fix stylesheet not working in Windows CHM htmlhelp docs and add warning that they are deprecated. Contributed by C.A.M. Gerlach.

  • gh-95454: Replaced incorrectly written true/false values in documentiation. Patch by Robert O’Shea

  • gh-95451: Update library documentation with availability information on WebAssembly platforms wasm32-emscripten and wasm32-wasi.

  • gh-95415: Use consistent syntax for platform availability. The directive now supports a content body and emits a warning when it encounters an unknown platform.

  • gh-94321: Document the PEP 246 style protocol type sqlite3.PrepareProtocol.

  • gh-86128: Document a limitation in ThreadPoolExecutor where its exit handler is executed before any handlers in atexit.

  • gh-61162: Clarify sqlite3 behavior when How to use the connection context manager.

  • gh-87260: Align sqlite3 argument specs with the actual implementation.

  • gh-86986: The minimum Sphinx version required to build the documentation is now 3.2.

  • gh-88831: Augmented documentation of asyncio.create_task(). Clarified the need to keep strong references to tasks and added a code snippet detailing how to do this.

  • gh-86438: Clarify that -W and PYTHONWARNINGS are matched literally and case-insensitively, rather than as regular expressions, in warnings.

  • gh-93031: Update tutorial introduction output to use 3.10+ SyntaxError invalid range.

  • gh-92240: Added release dates for “What’s New in Python 3.X” for 3.0, 3.1, 3.2, 3.8 and 3.10

  • bpo-47161: Document that pathlib.PurePath does not collapse initial double slashes because they denote UNC paths.

  • bpo-40838: Document that inspect.getdoc(), inspect.getmodule(), and inspect.getsourcefile() might return None.

  • bpo-43689: The Differ documentation now also mentions other whitespace characters, which make it harder to understand the diff output.

  • bpo-38056: Overhaul the Error Handlers documentation in codecs.

  • bpo-13553: Document tkinter.Tk args.

Tests

  • gh-95027: On Windows, when the Python test suite is run with the -jN option, the ANSI code page is now used as the encoding for the stdout temporary file, rather than using UTF-8 which can lead to decoding errors. Patch by Victor Stinner.

  • gh-96624: Fixed the failure of repeated runs of test.test_unittest caused by side effects in test_dotted_but_module_not_loaded.

  • gh-95243: Mitigate the inherent race condition from using find_unused_port() in testSockName() by trying to find an unused port a few times before failing. Patch by Ross Burton.

  • gh-95573: Lib/test/test_asyncio/test_ssl.py exposed a bug in the macOS kernel where intense concurrent load on non-blocking sockets occasionally causes errno.ENOBUFS (“No buffer space available”) to be emitted. FB11063974 filed with Apple, in the mean time as a workaround buffer size used in tests on macOS is decreased to avoid intermittent failures. Patch by Fantix King.

  • gh-95280: Fix problem with test_ssl test_get_ciphers on systems that require perfect forward secrecy (PFS) ciphers.

  • gh-95212: Make multiprocessing test case test_shared_memory_recreate parallel-safe.

  • gh-95218: Move tests for importlib.resources into test_importlib.resources.

  • gh-93963: Updated tests to use preferred location for importlib.resources ABCs.

  • gh-94675: Add a regression test for re exponentional slowdown when using rjsmin.

  • gh-91330: Added more tests for dataclasses to cover behavior with data descriptor-based fields.

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

  • gh-94315: Tests now check for DAC override capability instead of relying on os.geteuid().

  • gh-54781: Rename test_tk to test_tkinter, and rename test_ttk_guionly to test_ttk. Patch by Victor Stinner.

  • gh-93839: Move Lib/ctypes/test/ to Lib/test/test_ctypes/. Patch by Victor Stinner.

  • gh-93951: In test_bdb.StateTestCase.test_skip, avoid including auxiliary importers.

  • gh-93957: Provide nicer error reporting from subprocesses in test_venv.EnsurePipTest.test_with_pip.

  • gh-93884: Add test cases for PyNumber_ToBase() that take a large number or a non-int object as parameter.

  • gh-93852: test_asyncio, test_logging, test_socket and test_socketserver now create AF_UNIX domains in the current directory to no longer fail with OSError("AF_UNIX path too long") if the temporary directory (the TMPDIR environment variable) is too long. Patch by Victor Stinner.

  • gh-93353: regrtest now checks if a test leaks temporary files or directories if run with -jN option. Patch by Victor Stinner.

  • gh-84461: run_tests.py now handles cross compiling env vars correctly and pass HOSTRUNNER to regression tests.

  • gh-93616: test_modulefinder now creates a temporary directory in ModuleFinderTest.setUp() instead of module scope.

  • gh-93575: Fix issue with test_unicode test_raiseMemError. The test case now use test.support.calcobjsize to calculate size of PyUnicode structs. sys.getsizeof() may return different size when string has UTF-8 memory.

  • gh-90473: WASI does not have a chmod(2) syscall. os.chmod() is now a dummy function on WASI. Skip all tests that depend on working os.chmod().

  • gh-90473: Skip tests on WASI that require symlinks with absolute paths.

  • gh-57539: Increase calendar test coverage for calendar.LocaleTextCalendar.formatweekday().

  • gh-90473: Skip symlink tests on WASI. wasmtime uses openat2(2) with RESOLVE_BENEATH flag, which prevents symlinks with absolute paths.

  • gh-89858: Fix test_embed for out-of-tree builds. Patch by Kumar Aditya.

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in test_imaplib.py.

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in test_zipimport.py

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in test_py_compile.py

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in test_sys_settrace.py.

  • gh-92886: Fixing tests that fail when running with optimizations (-O) in _test_multiprocessing.py

  • gh-92670: Skip test_shutil.TestCopy.test_copyfile_nonexistent_dir test on AIX as the test uses a trailing slash to force the OS consider the path as a directory, but on AIX the trailing slash has no effect and is considered as a file.

  • gh-92514: Remove unused test.support.BasicTestRunner. Patch by Jelle Zijlstra.

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

Build

  • gh-96761: Fix the build process of clang compiler for _bootstrap_python if LTO optimization is applied. Patch by Matthias Görgens and Donghee Na.

  • gh-96883: wasm32-emscripten builds for browsers now include concurrent.futures for asyncio and unittest.mock.

  • gh-85936: CPython now uses the ThinLTO option as the default policy if the Clang compiler accepts the flag. Patch by Donghee Na.

  • gh-96729: Ensure that Windows releases built with Tools\msi\buildrelease.bat are upgradable to and from official Python releases.

  • gh-96269: Shared module targets now depend on new MODULE_DEPS variable, which includes EXPORTSYMS. This fixes a build order issue on unsupported AIX platform.

  • gh-84461: wasm32-emscripten platform no longer builds resource module, getresuid(), getresgid(), and their setters. The APIs are stubs and not functional.

  • gh-95973: Add a new --with-dsymutil configure option to link debug information in macOS. Patch by Pablo Galindo.

  • gh-90536: Use the BOLT post-link optimizer to improve performance, particularly on medium-to-large applications.

  • gh-93744: Remove the configure --with-cxx-main build option: it didn’t work for many years. Remove the MAINCC variable from configure and Makefile. Patch by Victor Stinner.

  • gh-94801: Fix a regression in configure script that caused some header checks to ignore custom CPPFLAGS. The regression was introduced in gh-94802.

  • gh-95145: wasm32-wasi builds no longer depend on WASIX’s pthread stubs. Python now has its own stubbed pthread API.

  • gh-95174: Python now detects missing dup function in WASI and works around some missing errno, select, and socket constants.

  • gh-95174: Python now skips missing socket functions and methods on WASI. WASI can only create sockets from existing fd / accept and has no netdb.

  • gh-95085: Platforms wasm32-unknown-emscripten and wasm32-unknown-wasi have been promoted to PEP 11 tier 3 platform support.

  • gh-94847: Fixed _decimal module build issue on GCC when compiling with LTO and pydebug. Debug builds no longer force inlining of functions.

  • gh-94841: Fix the possible performance regression of PyObject_Free() compiled with MSVC version 1932.

  • gh-94801: configure now uses custom flags like ZLIB_CFLAGS and ZLIB_LIBS when searching for headers and libraries.

  • gh-94773: deepfreeze.py now supports code object with frozensets that contain incompatible, unsortable types.

  • gh-94682: Build and test with OpenSSL 1.1.1q

  • gh-90005: Dependencies of readline and curses module are now detected in configure script with pkg-config. Only ncurses / ncursesw are detected automatically. The old curses library is not configured automatically. Workaround for missing termcap or tinfo library has been removed.

  • gh-90005: Fix building _ctypes extension without pkg-config.

  • gh-90005: _dbm module dependencies are now detected by configure.

  • gh-94404: makesetup now works around an issue with sed on macOS and uses correct CFLAGS for object files that end up in a shared extension. Module CFLAGS are used before PY_STDMODULE_CFLAGS to avoid clashes with system headers.

  • gh-93939: C extension modules are now built by configure and make instead of distutils and setup.py.

  • gh-93939: The 2to3, idle, and pydoc scripts are now generated and installed by Makefile instead of setup.py.

  • gh-94280: Updated pegen regeneration script on Windows to find and use Python 3.9 or higher. Prior to this, pegen regeneration already required 3.9 or higher, but the script may have used lower versions of Python.

  • gh-93584: Address race condition in Makefile when installing a PGO build. All test and install targets now depend on all target.

  • gh-93491: configure now detects and reports PEP 11 support tiers.

  • gh-69093: Fix Modules/Setup.stdlib.in rule for _sqlite3 extension.

  • gh-93207: va_start() with two parameters, like va_start(args, format), is now required to build Python. va_start() is no longer called with a single parameter. Patch by Kumar Aditya.

  • gh-93202: Python now always use the %zu and %zd printf formats to format a size_t or Py_ssize_t number. Building Python 3.12 requires a C11 compiler, so these printf formats are now always supported. Patch by Victor Stinner.

  • gh-90473: Disable pymalloc and increase stack size on wasm32-wasi.

  • bpo-34449: Drop invalid compiler switch -fPIC for HP aCC on HP-UX. Patch by Michael Osipov.

Windows

  • gh-98360: Fixes multiprocessing spawning child processes on Windows from a virtual environment to ensure that child processes that also use multiprocessing to spawn more children will recognize that they are in a virtual environment.

  • gh-98414: Fix py.exe launcher handling of -V:<company>/ option when default preferences have been set in environment variables or configuration files.

  • gh-97728: Fix possible crashes caused by the use of uninitialized variables when pass invalid arguments in os.system() on Windows and in Windows-specific modules (like winreg).

  • gh-90989: Made Python Launcher for Windows install per-user by default (unless an all users install already exists), and clarify some text in the installer.

  • gh-97649: The Tools directory is no longer installed on Windows

  • gh-96965: Update libffi to 3.4.3

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

  • gh-96559: Fixes the Windows launcher not using the compatible interpretation of default tags found in configuration files when no tag was passed to the command.

  • gh-94781: Fix pcbuild.proj to clean previous instances of output files in Python\deepfreeze and Python\frozen_modules directories on Windows. Patch by Charlie Zhao.

  • gh-89545: Updates platform code getting the Windows version to use native Windows Management Instrumentation (WMI) queries to determine OS version, type, and architecture.

  • gh-95733: Make certain requirements of the Windows Store package optional to allow installing on earlier updates of Windows.

  • gh-95656: Enable the enable_load_extension() sqlite3 API.

  • gh-95587: Fixes some issues where the Windows installer would incorrectly detect certain features of an existing install when upgrading.

  • gh-94399: Restores the behaviour of Python Launcher for Windows for /usr/bin/env shebang lines, which will now search PATH for an executable matching the given command. If none is found, the usual search process is used.

  • gh-95445: Fixes the unsuccessful removal of the HTML document directory when uninstalling with Windows msi.

  • gh-95359: Fix Python Launcher for Windows handling of py.ini commands (it was incorrectly expecting a py_ prefix on keys) and crashes when reading per-user configuration file.

  • gh-95285: Fix Python Launcher for Windows handling of command lines where it is only passed a short executable name.

  • gh-90844: Allow virtual environments to correctly launch when they have spaces in the path.

  • gh-94772: Fix incorrect handling of shebang lines in py.exe launcher

  • gh-94018: zipfile will now remove trailing spaces from path components when extracting files on Windows.

  • gh-93824: Drag and drop of files onto Python files in Windows Explorer has been enabled for Windows ARM64.

  • gh-43414: os.get_terminal_size() now attempts to read the size from any provided handle, rather than only supporting file descriptors 0, 1 and 2.

  • gh-92817: Ensures that py.exe will prefer an active virtual environment over default tags specified with environment variables or through a py.ini file.

  • gh-92984: Explicitly disable incremental linking for non-Debug builds

  • gh-92841: asyncio no longer throws RuntimeError: Event loop is closed on interpreter exit after asynchronous socket activity. Patch by Oleg Iarygin.

  • bpo-46907: Update Windows installer to use SQLite 3.38.4.

  • gh-91061: Accept os.PathLike for the argument to winsound.PlaySound

  • bpo-42658: Support native Windows case-insensitive path comparisons by using LCMapStringEx instead of str.lower() in ntpath.normcase(). Add LCMapStringEx to the _winapi module.

  • bpo-38704: Prevent installation on unsupported Windows versions.

macOS

  • gh-97897: The macOS 13 SDK includes support for the mkfifoat and mknodat system calls. Using the dir_fd option with either os.mkfifo() or os.mknod() could result in a segfault if cpython is built with the macOS 13 SDK but run on an earlier version of macOS. Prevent this by adding runtime support for detection of these system calls (“weaklinking”) as is done for other newer syscalls on macOS.

IDLE

  • gh-97527: Fix a bug in the previous bugfix that caused IDLE to not start when run with 3.10.8, 3.12.0a1, and at least Microsoft Python 3.10.2288.0 installed without the Lib/test package. 3.11.0 was never affected.

  • gh-65802: Document handling of extensions in Save As dialogs.

  • gh-95191: Include prompts when saving Shell (interactive input and output).

  • gh-95511: Fix the Shell context menu copy-with-prompts bug of copying an extra line when one selects whole lines.

  • gh-95471: In the Edit menu, move Select All and add a new separator.

  • gh-95411: Enable using IDLE’s module browser with .pyw files.

  • gh-89610: Add .pyi as a recognized extension for IDLE on macOS. This allows opening stub files by double clicking on them in the Finder.

Tools/Demos

  • gh-68686: Remove ptags and eptags scripts.

  • gh-97681: Remove the Tools/demo/ directory which contained old demo scripts. A copy can be found in the old-demos project. Patch by Victor Stinner.

  • gh-97669: Remove outdated example scripts of the Tools/scripts/ directory. A copy can be found in the old-demos project. Patch by Victor Stinner.

  • gh-95853: The wasm_build.py script now pre-builds Emscripten ports, checks for broken EMSDK versions, and warns about pkg-config env vars.

  • gh-95853: The new tool Tools/wasm/wasm_builder.py automates configure, compile, and test steps for building CPython on WebAssembly platforms.

  • gh-95731: Fix handling of module docstrings in Tools/i18n/pygettext.py.

  • gh-93939: Add script Tools/scripts/check_modules.py to check and validate builtin and shared extension modules. The script also handles Modules/Setup and will eventually replace setup.py.

  • gh-94538: Fix Argument Clinic output to custom file destinations. Patch by Erlend E. Aasland.

  • gh-94430: Allow parameters named module and self with custom C names in Argument Clinic. Patch by Erlend E. Aasland

  • gh-86087: The Tools/scripts/parseentities.py script used to parse HTML4 entities has been removed.

C API

Python 3.11.0 beta 1

Release date: 2022-05-06

Security

  • gh-57684: Add the -P command line option and the PYTHONSAFEPATH environment variable to not prepend a potentially unsafe path to sys.path. Patch by Victor Stinner.

Core and Builtins

  • gh-89519: Chaining classmethod descriptors (introduced in bpo-19072) is deprecated. It can no longer be used to wrap other descriptors such as property(). The core design of this feature was flawed, and it caused a number of downstream problems.

  • gh-92345: pymain_run_python() now imports readline and rlcompleter before sys.path is extended to include the current working directory of an interactive interpreter. Non-interactive interpreters are not affected.

  • bpo-43857: Improve the AttributeError message when deleting a missing attribute. Patch by Géry Ogam.

  • gh-92245: Make sure that PEP 523 is respected in all cases. In 3.11a7, specialization may have prevented Python-to-Python calls respecting PEP 523.

  • gh-92203: Add a closure keyword-only parameter to exec(). It can only be specified when exec-ing a code object that uses free variables. When specified, it must be a tuple, with exactly the number of cell variables referenced by the code object. closure has a default value of None, and it must be None if the code object doesn’t refer to any free variables.

  • gh-91173: Disable frozen modules in debug builds. Patch by Kumar Aditya.

  • gh-92114: Improve error message when subscript a type with __class_getitem__ set to None.

  • gh-92112: Fix crash triggered by an evil custom mro() on a metaclass.

  • gh-92063: The PRECALL_METHOD_DESCRIPTOR_FAST_WITH_KEYWORDS instruction now ensures methods are called only on objects of the correct type.

  • gh-92031: Deoptimize statically allocated code objects during Py_FINALIZE() so that future _PyCode_Quicken calls always start with unquickened code.

  • gh-92036: Fix a crash in subinterpreters related to the garbage collector. When a subinterpreter is deleted, untrack all objects tracked by its GC. To prevent a crash in deallocator functions expecting objects to be tracked by the GC, leak a strong reference to these objects on purpose, so they are never deleted and their deallocator functions are not called. Patch by Victor Stinner.

  • gh-92032: The interpreter can now autocomplete soft keywords, as of now match, case, and _ (wildcard pattern) from PEP 634.

  • gh-87999: The warning emitted by the Python parser for a numeric literal immediately followed by keyword has been changed from deprecation warning to syntax warning.

  • gh-91869: Fix an issue where specialized opcodes with extended arguments could produce incorrect tracing output or lead to assertion failures.

  • gh-91603: Speed up types.UnionType instantiation. Based on patch provided by Yurii Karabas.

  • gh-89373: If Python is built in debug mode, Python now ensures that deallocator functions leave the current exception unchanged. Patch by Victor Stinner.

  • gh-91632: Fix a minor memory leak at exit: release the memory of the generic_alias_iterator type. Patch by Donghee Na.

  • gh-81548: Octal escapes with value larger than 0o377 now produce a DeprecationWarning. In a future Python version they will be a SyntaxWarning and eventually a SyntaxError.

  • bpo-43950: Use a single compact table for line starts, ends and column offsets. Reduces memory consumption for location info by half

  • gh-91102: Use Argument Clinic for EncodingMap. Patch by Oleg Iarygin.

  • gh-91636: Fixed a crash in a garbage-collection edge-case, in which a PyFunction_Type.tp_clear function could leave a python function object in an inconsistent state.

  • gh-91603: Speed up isinstance() and issubclass() checks for types.UnionType. Patch by Yurii Karabas.

  • gh-91625: Fixed a bug in which adaptive opcodes ignored any preceding EXTENDED_ARGs on specialization failure.

  • gh-78607: The LLTRACE special build now looks for the name __lltrace__ defined in module globals, rather than the name __ltrace__, which had been introduced as a typo.

  • gh-91576: Speed up iteration of ascii strings by 50%. Patch by Kumar Aditya.

  • gh-89279: Improve interpreter performance on Windows by inlining a few specific macros.

  • gh-91502: Add a new _PyFrame_IsEntryFrame() API function, to check if a PyFrameObject is an entry frame. Patch by Pablo Galindo.

  • gh-91266: Refactor the bytearray strip methods strip, lstrip and rstrip to use a common implementation.

  • gh-91479: Replaced the __note__ field of BaseException (added in an earlier version of 3.11) with the final design of PEP 678. Namely, BaseException gets an add_note() method, and its __notes__ field is created when necessary.

  • gh-46055: Speed up right shift of negative integers, by removing unnecessary creation of temporaries. Original patch by Xinhang Xu, reworked by Mark Dickinson.

  • gh-91462: Make the interpreter’s low-level tracing (lltrace) feature output more readable by displaying opcode names (rather than just numbers), and by displaying stack contents before each opcode.

  • gh-89455: Fixed an uninitialized bool value in the traceback printing code path that was introduced by the initial bpo-45292 exception groups work.

  • gh-91421: Fix a potential integer overflow in _Py_DecodeUTF8Ex.

  • gh-91428: Add static const char *const _PyOpcode_OpName[256] = {...}; to opcode.h for debug builds to assist in debugging the Python interpreter. It is now more convenient to make various forms of debugging output more human-readable by including opcode names rather than just the corresponding decimal digits.

  • bpo-47120: Make POP_JUMP_IF_TRUE, POP_JUMP_IF_FALSE, POP_JUMP_IF_NONE and POP_JUMP_IF_NOT_NONE virtual, mapping to new relative jump opcodes.

  • bpo-45317: Add internal documentation explaining design of new (for 3.11) frame stack.

  • bpo-47197: ctypes used to mishandle void return types, so that for instance a function declared like ctypes.CFUNCTYPE(None, ctypes.c_int) would be called with signature int f(int) instead of void f(int). Wasm targets require function pointers to be called with the correct signatures so this led to crashes. The problem is now fixed.

  • bpo-47120: Make opcodes JUMP_IF_TRUE_OR_POP and JUMP_IF_FALSE_OR_POP relative rather than absolute.

  • bpo-47177: Replace the f_lasti member of the internal _PyInterpreterFrame structure with a prev_instr pointer, which reduces overhead in the main interpreter loop. The f_lasti attribute of Python-layer frame objects is preserved for backward-compatibility.

  • bpo-46961: Integer mod/remainder operations, including the three-argument form of pow(), now consistently return ints from the global small integer cache when applicable.

  • bpo-46962: Classes and functions that unconditionally declared their docstrings ignoring the --without-doc-strings compilation flag no longer do so.

    The classes affected are ctypes.UnionType, pickle.PickleBuffer, testcapi.RecursingInfinitelyError, and types.GenericAlias.

    The functions affected are 24 methods in ctypes.

    Patch by Oleg Iarygin.

  • bpo-46942: Use Argument Clinic for the types.MethodType constructor. Patch by Oleg Iarygin.

  • bpo-46764: Fix wrapping bound methods with @classmethod

  • bpo-43464: Optimize set.intersection() for non-set arguments.

  • bpo-46721: Optimize set.issuperset() for non-set argument.

  • bpo-46509: Add type-specialized versions of the Py_DECREF(), and use them for float, int, str, bool, and None to avoid pointer-chasing at runtime where types are known at C compile time.

  • bpo-46045: Do not use POSIX semaphores on NetBSD

  • bpo-36819: Fix crashes in built-in encoders with error handlers that return position less or equal than the starting position of non-encodable characters.

  • bpo-34093: marshal.dumps() uses FLAG_REF for all interned strings. This makes output more deterministic and helps reproducible build.

  • bpo-26579: Added object.__getstate__ which provides the default implementation of the __getstate__() method.

    Copying and pickling instances of subclasses of builtin types bytearray, set, frozenset, collections.OrderedDict, collections.deque, weakref.WeakSet, and datetime.tzinfo now copies and pickles instance attributes implemented as slots.

Library

  • gh-87901: Add the encoding parameter to os.popen().

  • gh-90997: Fix an issue where dis utilities may interpret populated inline cache entries as valid instructions.

  • gh-92332: Deprecate typing.Text (removal of the class is currently not planned). Patch by Alex Waygood.

  • Deprecate nested classes in enum definitions becoming members – in 3.13 they will be normal classes; add member and nonmember functions to allow control over results now.

  • gh-92356: Fixed a performance regression in ctypes function calls.

  • gh-90997: Show the actual named values stored in inline caches when show_caches=True is passed to dis utilities.

  • gh-92301: Prefer close_range() to iterating over procfs for file descriptor closing in subprocess for better performance.

  • gh-67248: Sort the miscellaneous topics in Cmd.do_help()

  • gh-92210: Port socket.__init__ to Argument Clinic. Patch by Cinder.

  • gh-80010: Add support for generalized ISO 8601 parsing to datetime.datetime.fromisoformat(), datetime.date.fromisoformat() and datetime.time.fromisoformat(). Patch by Paul Ganssle.

  • gh-92118: Fix a 3.11 regression in contextmanager(), which caused it to propagate exceptions with incorrect tracebacks.

  • gh-90887: Adding