pyo3-build-config

This patch fixes a regression in PyO3 0.29.1 which broke PyPy 3.11 compatibility (#[pyclass] types would crash PyPy on instance deletion).

A few further fixes have also landed with similar themes to PyO3 0.29.1: fixes to minor reference counting bugs, rough edges which would cause crashes, issues which would cause failed builds, and fixes to experimental-inspect type stub generation.

For a full list of the exact fixes please consult the CHANGELOG.

Thank you to the following contributors for the improvements:

@davidhewitt
@dependabot[bot]
@ImFeH2
@musicinmybrain
@Tpt
@WaterWhisperer

Packaging

• Add PYO3_USE_RAW_DYLIB=0 opt-out of raw-dylib linking for Windows. #6185

Fixed

• Fix PyO3 0.29 regression with failure to link under Cygwin / MSYS2. #6185
• Fix stubs generation for field getters (#[pyo3(get)]) when IntoPyObject is only implemented on references of the field type. #6276
• Fix #[classmethod] magic methods receiving the instance instead of its type when invoked through a type slot. #6283
• Fix pyo3_build_config::add_libpython_rpath_link_args emitting Unix-style rpath linker arguments on Windows and Cygwin. #6284
• Fix PyO3 0.29.1 regression on PyPy causing crashes when deallocating #[pyclass] instances. #6294
• Fix missing trailing nul in Python 3.9 #[pyclass] docstrings. #6296
• Fix reference count leak of #[classattr] values created from fn items. #6297

This patch is a stack of fixes for PyO3 0.29. Particular themes include:

• Fixes addressing build failures with newer interpreters such as GraalPy 3.13 and CPython 3.15
• Fixes resolving potential memory leaks inside #[pyclass] implementation internals
• Fixes to the new experimental-inspect type stub machinery

For a full list of the fixes in these above themes and more, please consult the CHANGELOG.

Thank you to the following contributors for the improvements:

@alex
@bschoenmaeckers
@chirizxc
@davidhewitt
@dependabot[bot]
@exg
@ImFeH2
@IvanIsCoding
@jonasdedden
@MatthieuDartiailh
@msimacek
@ngoldbaum
@Person-93
@ratazzi
@rewitt94
@scott-griffiths
@ShiroKSH
@tobni
@Tpt
@WaterWhisperer

Changed

• Use the inline definition of Py_TYPE in the unlimited API on 3.14+ #6179

Fixed

• Fix incorrect pointer arithmetic in FFI definitions PyObject_GET_WEAKREFS_LISTPTR and PyHeapType_GET_MEMBERS. #6145
• Fix compilation error with nightly feature on PyPy and GraalPy due to !Ungil implementations for FFI types not available on those platforms. #6146
• Fix append_to_inittab and PyInit_<module> internal module definition corruption on 32-bit and big-endian platforms on Python 3.15+. #6150
• Fix return value of PyClassGuardMutSuper::as_super being scoped to the full guard lifetime, now the &mut borrow of the as_super() call. #6181
• Fix builds for free-threaded interpreters older than 3.15 erroring with "cannot set a minimum Python version" when an abi3t-py3* feature is enabled and the configuration comes from PYO3_CONFIG_FILE, sysconfigdata or cross-compilation defaults. #6192
• Fix a memory leak when deallocating #[pyclass(dict)] instances with a populated __dict__. #6198
• Fix an abort inside a #[pyclass]'s GC traversal when the traversal is stopped early. #6206
• Fix reference cycles through the __dict__ of a #[pyclass(dict)] never being collected. #6206
• Fix building on GraalPy 3.13. #6208
• Fix reference count leak of references to #[pyclass] type objects held by their instances on instance deallocation. #6224
• Fix FFI definitions PyByteArray_GET_SIZE, PyList_GET_SIZE, and PySet_GET_SIZE to use an atomic load for free-threaded Python. #6230
• Fix a memory leak on Python 3.11 and 3.12 where creating an instance of a #[pyclass(dict)] class leaked one empty dict per instance. #6234
• Fix experimental-inspect type stubs to emit the arguments of many magic methods as positional-only to match runtime behavior, rather than positional-or-keyword. #6239
• Fix experimental-inspect type stubs to emit the Python name rather than the Rust name for #[pyfunction(name = "...")]. #6254
• Fix experimental-inspect generating invalid internal JSON when #[pymodule] members are gated by #[cfg]. #6255
• Fix __inplace_concat__ and __inplace_repeat__ overriding __concat__ and __repeat__ when both were defined. #6260
• Fix conversion of out-of-range time::Duration values to return OverflowError instead of panicking. #6266
• Fix experimental-inspect type stubs padding blank lines inside indented docstrings. #6270

This release is a relatively large release with improvements across many areas of PyO3's API.

Build and packaging changes

This release brings full support for Python 3.15 beta. We encourage downstream projects to begin testing and distributing Python 3.15 beta wheels so that the ecosystem can prepare for the 3.15 final release later in the year.

Alongside Python 3.15 support comes support for its new "abi3t" stable ABI which supports both free-threaded and gil-enabled Python builds. For projects distributing stable ABI wheels, we recommend distributing (for each OS/architecture) an abi3 wheel built for your minimum supported Python version, a 3.14t version-specific wheel for free-threaded Python 3.14, and an abi3t wheel to support Python 3.15 (and future versions).

Support for Python 3.7 has been dropped. Support for Python 3.13t, the first experimental free-threaded release of CPython, has also been dropped. 3.14t (and soon 3.15t) is more stable, performant, and the starting point for CPython's own declaration of "support" for the free-threaded build.

The PyO3 build process (via the pyo3-build-config crate) has been adjusted to reduce the cost of rebuilds when the environment used to detect the Python interpreter changes; pyo3-build-config and pyo3-macros will no longer be rebuilt in such cases (although pyo3-ffi and crates downstream of it still will be rebuilt). As a consequence the pyo3_build_config APIs now require crates to have a direct dependency on pyo3 or pyo3-ffi. We hope to continue to reduce rebuild frequency and cost in a future PyO3 release.

Security updates

With the recent boom in AI-assisted security scanning, PyO3 has inevitably had several correctness issues exposed by AI-assisted scanning.

In particular, PyO3 0.29 fixes two security vulnerabilities we will be releasing to the RustSec Advisory Database imminently:

• Missing Sync bound on PyCFunction::new_closure closures
• Possible out of bounds read in BoundTupleIterator::nth_back and BoundListIterator::nth_back

Any code using the above APIs is advised to update as soon as possible.

This release also contains several other minor breaking changes to close soundness holes uncovered by AI-assisted scanning. Our assessment as maintainers was that, excluding the two vulnerability cases listed above, these correctness issues would likely have crashed immediately upon user testing rather than leading to attacker-exploitable pathways. We nevertheless wanted to see them closed without the usual deprecation cycle. These cases are noted in the migration guide.

Other major themes in this release

New in this release is a CLI in pyo3-introspection to generate type stubs along with the experimental-inspect feature. Downstream, maturin has also gained support to generate type stubs using the feature. The feature is reaching a point where substantial amount of type stubs can be generated automatically. We would like to encourage users to begin using this feature and helping us find what functionality is missing, with a hope we can declare its API stable given sufficient feedback.

A substantial amount of effort has been invested in pyo3-ffi as part of the process of extending it with 3.15's new APIs. There have been many missing APIs from older Python versions added. There have also been a number of fixes to incorrect definitions (these are breaking changes, but also necessary for correctness); we hope there will be far fewer such cases in the future due to more comprehensive checking added to PyO3's CI. Finally, many private CPython APIs (those with _Py underscore-named prefix) have been removed from pyo3-ffi's public API.

In closing

There are also many other incremental improvements, bug fixes and smaller features; full detail can be found in the CHANGELOG.

Please consult the migration guide for help upgrading.

Thank you to everyone who contributed code, documentation, design ideas, bug reports, and feedback. The following contributors' commits are included in this release:

@Alc-Alc
@alex
@anuraaga
@BD103
@bschoenmaeckers
@Cheukting
@chirizxc
@ChristopherRabotin
@clin1234
@codeguru42
@davidhewitt
@dependabot[bot]
@Embers-of-the-Fire
@funsafemath
@Harikeshav-R
@hoodmane
@Icxolu
@IntrepidT
@jelmer
@luxedo
@MatthieuDartiailh
@maurosilber
@mejrs
@messense
@ngoldbaum
@Person-93
@quyentonndbs
@rara64
@staticintlucas
@tbates-redarc
@tdyas
@Tpt
@winstxnhdw

Packaging

• Support the new PEP 803 abi3t ABI with new abi3t and abi3t-py315 features. #5807
• pyo3-macros-backend no longer depends on pyo3-build-config. #5809
• Drop support for Python 3.13t (3.14t and above continue to be supported; CPython declared free-threading supported starting with Python 3.14). #5865
• Drop support for Python 3.7. #5912
• Extend range of supported versions of hashbrown optional dependency to include version 0.17. #5973
• Support Python 3.15.0b1. #6014
• pyo3-ffi is now no_std. #6022

Added

• Add PyErr::set_traceback to set the traceback of an exception object. #5349
• Add PyUnicodeDecodeError::new_err_from_utf8 to create a PyErr from a str::Utf8Error. #5668
• experimental-inspect: implement INPUT_TYPE and OUTPUT_TYPE on optional third-party crate conversions. #5770
• experimental-inspect: include doc comments in generated stubs. #5782
• Add pyo3_build_config::PythonAbi, pyo3_build_config::PythonAbiKind, pyo3_build_config::PythonAbiBuilder, pyo3_build_config::InterpreterConfig::target_abi, and pyo3_build_config::InterpreterConfigBuilder::target_abi. #5807
• Add Borrowed::get as an equivalent to Bound::get and Py::get. #5849
• Add PyFrame::new, PyTraceBack::new, and PyFrameMethods::line_number. #5857
• Add PyUntypedBuffer::obj to retrieve the Python object owning the buffer. #5870
• Add PyCapsule::new_with_value and PyCapsule::new_with_value_and_destructor. #5881
• Add PyErr::set_context and PyErr::context. #5887
• Add a small CLI to pyo3-introspection to generate stubs. #5904
• Add Python::version_str. #5921
• Add TryFrom<&Bound<T>> for PyRef<T>, PyRefMut<T>, PyClassGuard<T> and PyClassGuardMut<T>. #5922
• Add From<&Bound<T>> for Bound<T> and Py<T> #5922
• Add PyDictMethods::set_default and PyDictMethods::set_default_ref to allow atomically setting default values in a PyDict. #5955
• add PyFrameMethods::outer|code|var|builtins|globals|locals. #5967
• Add From conversions for PyErr from std::time::TryFromFloatSecsError, std::time::SystemTimeError, std::path::StripPrefixError, std::env::JoinPathsError, std::char::ParseCharError, and std::char::CharTryFromError. #6001
• Add pyo3_build_config::InterpreterConfigBuilder. #6034
• Add PyCapsule::import_pointer #6066
• Add PyClassGuardMapMut. #6073
• Expose PyListMethods::get_item_unchecked, PyTupleMethods::get_item_unchecked, and PyTupleMethods::get_borrowed_item_unchecked on abi3. #6075
• Add PyClassGuardMapSuper. #6104
• Add PyClassGuard and PyClassGuardMut to pyo3::prelude. #6112
• Add Debug impls for PyClassGuard and PyClassGuardMut. #6112
• Enable extending PyDateTime, PyDate, PyTime, PyDelta and PyTzInfo on abi3 with python 3.12+. #6115
• Expose PyFunction available on abi3. #6117
• FFI definitions:
  • Added FFI definitions PyUnstable_Object_IsUniquelyReferenced, PyUnstable_Object_IsUniquelyReferencedTemporary, PyUnstable_EnableTryIncref, and PyUnstable_TryIncref. #5828
  • Add FFI definitions ffi::PyErr_GetHandledException and ffi::PyErr_SetHandledException. #5887
  • Add FFI definition Py_HASH_SIPHASH13. #5891
  • Add FFI definition PyStructSequence_UnnamedField constant on Python 3.9 and up (or 3.11 with abi3 features). #5892
  • Add FFI definitions PyUnstable_InterpreterFrame_GetCode, PyUnstable_InterpreterFrame_GetLasti, PyUnstable_InterpreterFrame_GetLine, and PyUnstable_ExecutableKinds. #5932
  • Add FFI definitions PyMarshal_WriteLongToFile, PyMarshal_WriteObjectToFile, PyMarshal_ReadLongFromFile, PyMarshal_ReadShortFromFile, PyMarshal_ReadObjectFromFile, and PyMarshal_ReadLastObjectFromFile. #5934
  • Add FFI definitions PyObject_GetAIter, PyAIter_Check, PyMapping_HasKeyWithError, PyMapping_HasKeyStringWithError, PyMapping_GetOptionalItem, PyMapping_GetOptionalItemString, PySequence_ITEM, PySequence_Fast_GET_SIZE, PySequence_Fast_GET_ITEM, and PySequence_Fast_ITEMS. #5942
  • Add FFI definition compat::PyObject_HasAttrWithError. #5944
  • Add FFI definitions PyDict_SetDefault, PyDict_SetDefaultRef, PyDict_ContainsString, PyDict_Pop, PyDict_PopString, PyDict_ClearWatcher, PyDict_Watch, PyDict_Unwatch, and PyFrozenDict_New. #5947
  • Add FFI definitions PyDate_FromDate, PyDateTime_FromDateAndTime, PyDateTime_FromDateAndTimeAndFold, PyTime_FromTime, PyTime_FromTimeAndFold, and PyDelta_FromDSU. #5949
  • Add FFI definitions PyDict_SetDefaultRef and compat::PyDict_SetDefaultRef. #5955 versions.
  • Add FFI definitions for non-limited API header cpython/bytearrayobject.h. #5966
  • Add FFI definitions for non-limited API version of PyCellObject and associated functions. #5978
  • Add FFI definition PyErr_WarnExplicitObject. #5979
  • Add FFI definition PyTracebackObject. #5980
  • Add FFI definition PyTuple_FromArray on 3.15+. #5990
  • Add FFI definitions for the PEP 820 PySlot C API. #6014
  • Add FFI definitions for the critical section API in the limited API on Python 3.15 and newer. #6014
  • Add FFI definitions for PEP 757 PyLong import / export API on Python 3.14+. #6016
  • Add FFI definitions PyEval_SetProfileAllThreads and PyEval_SetTraceAllThreads. #6038
  • Add FFI definition Py_UNICODE_TODECIMAL. #6041

Changed

• Change exception enrichment on #[pyfunction] argument extraction error to use PyErr::add_note instead of replacing TypeError instances. #5349
• Deprecate super-class initialization via tuples. #5741
• Change module initialization uses the PyModExport and PyABIInfo APIs on Python 3.15+. #5753
• Deprecate Py<T>::get_refcnt and PyAnyMethods::get_refcnt in favor of pyo3::ffi::Py_REFCNT(obj.as_ptr()). #5797
• Change PyEnvironmentError, PyIOError, and PyWindowsError to be type aliases of PyOSError (as is the case in Python since 3.3). #5803
• Change pyo3_build_config::InterpreterConfig::from_interpreter to require an additional stable_abi_version argument. The old behavior is the same as passing None. #5807
• Change PyList::new to no longer have ExactSizeIterator bound. #5830
• experimental-inspect: emit #[classattribute] as plain Python class attributes and not functions annotated with @classattribute and @property. #5839
• experimental-inspect: use object as the input annotation type of magic methods that return NonImplemented if the input value is not of the correct type. #5841
• Deprecate pyo3-build-config/resolve-config feature. #5862
• Change pyo3-ffi to use raw-dylib for Windows linking. #5866
• Deprecate generate-import-lib feature. #5866
• Allow zero-sized types in PyCapsule::new. #5889
• PyDate::from_timestamp argument is now a f64 (the Python API expects a float and not an integer) #5896
• experimental-inspect: Change PathBuf::extract input type hint from str | os.PathLike to str | os.PathLike[str] #5897
• Remove lifetime from PythonVersionInfo. #5921
• Remove redundant type checks for methods where CPython guarantees the type of self. #5930
• Elide temporary reference count cycles inside PyAnyMethods::call, PyAnyMethods::call1 and PyAnyMethods::call_method1 for arguments passed as Rust tuples containing borrowed references to Python objects. #5941
• Allow type annotations to be used in #[pyo3(signature = ...)] when experimental-inspect feature is not enabled (they will be ignored). #5999
• pyo3-ffi will now rebuild when the Python virtual environment changes in-place. #6008
• Change module initialization on 3.15+ to use PEP 820 PySlot API internally. #6014
• Deprecate direct access to all pyo3_build_config::InterpreterConfig fields; getter methods have been added as replacements. #6034
• FFI definitions _PyCode_GetExtra, _PyCode_SetExtra, and _PyEval_RequestCodeExtraIndex have been updated to PyUnstable_Code_GetExtra, PyUnstable_Code_SetExtra, and PyUnstable_Eval_RequestCodeExtraIndex. #6038
• Change PyCapsule::import to return an error if the pointer is not properly aligned. #6066
• Change PyClassGuardMap to be only for PyClassGuard::map and return PyClassGuardMapMut from PyClassGuardMut::map. #6073
• Change with_critical_section_mutex2 closure to take Option<EnteredCriticalSection> instead of EnteredCriticalSection as the second argument. #6098
• PyClassGuardMut::as_super now returns PyClassGuardMutSuper. #6104
• experimental-inspect: Generate relative imports instead of absolute ones (useful if the stubs are not describing a root package) #6097

Removed

• Removed the broken (and unfixable) implementations of From<str::Utf8Error>, From<string::FromUtf16Error>, and From<char::DecodeUtf16Error> for PyErr. #5668
• Remove Py_TRACE_REFS support (unsupported from Python 3.13). #5824
• experimental-inspect: Remove the TypeInfo enum and the FromPyObject::type_input and IntoPyObject::type_output functions. They are replaced by the PyStaticExpr enum and the FromPyObject::INPUT_TYPE and the IntoPyObject::OUTPUT_TYPE associated constants. #5893
• Remove all functionality deprecated in PyO3 0.27. #6068
• FFI definitions:
  • Remove private FFI definitions _PyStack_AsDict, _PyObject_CallNoArg, _PyObject_FastCall, _PyObject_FastCallTstate. _PyObject_VectorcallTstate, _PyObject_MakeTpCall, _Py_CheckFunctionResult, _PyObject_CallFunction_SizeT, _PyObject_CallMethod_SizeT, and _PySequence_IterSearch. #5942
  • Remove FFI definitions PY_ITERSEARCH_COUNT, PY_ITERSEARCH_INDEX, and PY_ITERSEARCH_CONTAINS. #5942
  • Removed private FFI definitions _PySet_NextEntry, and _PyLong_NumBits. #5946
  • Remove private FFI definitions _PyFloat_CAST, _PyRun_SimpleFileObject, _PyRun_AnyFileObject, _PyRun_InteractiveLoopObject, _PyUnicode_CheckConsistency, _PyUnicode_COMPACT_DATA, _PyUnicode_NONCOMPACT_DATA, _PyUnicode_Ready, and _Py_HashBytes. #6036
  • Remove private FFI definition _PyEval_EvalFrameDefault. #6038
  • Remove private FFI definition _PyBytes_Resize. #6042
  • Remove private FFI definitions _PyErr_BadInternalCall, _Py_GetAllocatedBlocks, _PyObject_GC_Malloc, _PyObject_GC_Calloc, and _PyLong_NumBits. #6053
  • Remove Default for FFI definitions PyHeapTypeObject, PyObjectArenaAllocator, PyHash_FuncDef, and PyType_Spec. #6093

Fixed

• Fix add_libpython_rpath_link_args emitting rpath link args on wasm targets which don't support rpath. #5447
• Fix From<string::FromUtf8Error> and From<ffi::IntoStringError> for PyErr producing TypeError due to broken internals. #5668
• Fix PyMappingProxy::is_type_of and PyWeakrefReference::is_type_of not accepting subclasses. #5883
• Fix getattr_opt not treating AttributeError subclasses as missing attributes on Python < 3.13. #5985
• Fix compilation error for #[new] return types that contain named lifetimes. #5998
• Fix missing 'static bound on PyCapsule destructors. #6049
• Fix case where PyFrame::builtins could return a non-dict object. #6052
• Fix type confusion when returning a #[pyclass] from a different pyclass' #[new] method. #6062
• Fix soundness issue caused by variance in PyClassGuardMap by splitting off the mutable variant. #6073
• Fix nondeterministic JSON metadata emitted by the experimental-inspect proc macros (to enable reproducible builds). #6076
• Fix UB in PyEval_RestoreThread when the interpreter is shutting down on Python 3.13 and older (hang the thread instead of allowing pthread_exit to jump across Rust frames). #6085
• Fix possible out of bounds read in BoundListIterator and BoundTupleIterator's nth and nth_back implementations. #6086
• Fix BoundListIterator and BoundTupleIterator not being exhausted when nth or nth_back is called with N larger than the remaining count of items. #6086
• Fix missing Sync bound on closure type in PyCFunction::new_closure. #6096
• Fix soundness issue caused by exposing a mutable reference from PyClassGuardMut::as_super by moving into PyClassGuardMutSuper. #6104
• FFI definitions:
  • Fix missing FFI definition for PyTypeObject.tp_versions_used on Python 3.13 and newer. #5917
  • Mark FFI definitions no longer available on 3.11 and up: PyUnicode_Encode, PyUnicode_EncodeASCII, PyUnicode_EncodeCharmap, PyUnicode_EncodeDecimal, PyUnicode_EncodeLatin1, PyUnicode_EncodeRawUnicodeEscape, PyUnicode_EncodeUTF7, PyUnicode_EncodeUTF8, PyUnicode_EncodeUTF16, PyUnicode_EncodeUTF32, PyUnicode_EncodeUnicodeEscape, PyUnicode_TransformDecimalToASCII, and PyUnicode_TranslateCharmap. #6041
  • Mark FFI definition PyUnicode_ClearFreeList no longer available on 3.9 and up. #6041
  • Fix FFI definition PyErr_SetInterruptEx missing c_int return type. #6043
  • Fix return type of FFI definition PyBuffer_SizeFromFormat on Python 3.8 (was changed from c_int to Py_ssize_t on Python 3.9). #6090
  • Fix return type of FFI definition PyUnicode_Tailmatch on PyPy (is c_int, unlike CPython). #6090

This patch contains several fixes for stability of the PyO3 0.28.x series:

• Python::attach and Python::try_attach will no longer return before the thread initializing the interpreter has finished runnning site.py when using the auto-initialize feature.
• Fix unsoundness in PyBytesWriter::write_vectored when targeting the Python 3.15 prerelease interpreter.
• Fix possible deadlock in .into_pyobject() implementation for C-like #[pyclass] enums.

A couple of edge cases causing compile failures were also fixed.

Thank you to the following contributors for the improvements:

@alex
@bschoenmaeckers
@chirizxc
@davidhewitt
@Embers-of-the-Fire
@Icxolu
@maurosilber
@ngoldbaum

Fixed

• Fix compile error with #[pyclass(get_all)] on a type named Probe. #5837
• Fix compile error in debug builds related to _Py_NegativeRefcount with Python < 3.12. #5847
• Fix a race condition where Python::attach or try_attach could return before site.py had finished running. #5903
• Fix unsoundness in PyBytesWriter::write_vectored with Python 3.15 prerelease versions. #5907
• Fix deadlock in .into_pyobject() implementation for C-like #[pyclass] enums. #5928

This patch release contains a soundness fix for subclassing native types such as PyList with the abi3 feature enabled when targeting a minimum version of Python 3.12 or higher. (Support for doing such subclassing was newly added in PyO3 0.28.0.)

PyO3 0.28.0 and 0.28.1 will be yanked.

This release also contains a correction to the FFI definition PyType_GetTypeDataSize and incorrectly-generated __qualname__ on #[pyclass] enum variant types when using #[pyo3(name = "...")] option to rename the enum and/or variant.

Thank you to the following contributors for the improvements:

@davidhewitt
@Icxolu
@ngoldbaum

Fixed

• Fix complex enum __qualname__ not using python name #5815
• Fix FFI definition PyType_GetTypeDataSize (was incorrectly named PyObject_GetTypeDataSize). #5819
• Fix memory corruption when subclassing native types with abi3 feature on Python 3.12+ (newly enabled in PyO3 0.28.0). #5823

This patch contains a number of minor compile-time fixes for PyO3 0.28.0.

Thank you to the following contributors for the improvements:

@davidhewitt
@funsafemath
@ngoldbaum
@rara64
@tdyas

Fixed

• Fix *args / **kwargs support in experimental-async feature (regressed in 0.28.0). #5771
• Fix clippy::declare_interior_mutable_const warning inside #[pyclass] generated code on enums. #5772
• Fix ambiguous_associated_items compilation error when deriving FromPyObject or using #[pyclass(from_py_object)] macro on enums with Error variant. #5784
• Fix __qualname__ for complex #[pyclass] enum variants to include the enum name. #5796
• Fix missing std::sync::atomic::Ordering import for targets without atomic64. #5808

This release contains many improvements across PyO3's feature set:

• Proper support for __init__ methods for #[pyclass] types
• Support for #[deleter]s to complement the existing #[getter] and #[setter] attributes when implementing class "properties".
• Support for subclassing many Python types with the abi3 feature (requires Python 3.12+).
• A new #[pyclass(new = "from_fields")] option to automatically define the constructor from the class fields.
• Many corrections to FFI definitions (including removal of many private CPython methods)
• Many improvements to the experimental-inspect feature's functionality.

The minimum supported Rust version has been increased to Rust 1.83.

This release also switches #[pymodule] to use PEP 489 multi-phase initialization internally. This should have no immediate functional impact other than preparing PyO3 to support newer technologies such as Python subinterpreters.

There are also many other incremental improvements, bug fixes and smaller features; full detail can be found in the CHANGELOG.

Please consult the migration guide for help upgrading.

Thank you to everyone who contributed code, documentation, design ideas, bug reports, and feedback. The following contributors' commits are included in this release:

@ABorgna
@ahlinc
@alex
@altendky
@bazaah
@bschoenmaeckers
@chirizxc
@clin1234
@davidhewitt
@dependabot[bot]
@freakboy3742
@henryp3278
@Icxolu
@lazka
@LilyFirefly
@linkmauve
@lmmx
@lukaslueg
@MatthieuDartiailh
@MusicalNinjaDad
@ngoldbaum
@pkalivas
@reaperhulk
@RedKinda
@SilasMarvin
@SoroushMoosapour
@stijndcl
@tpoliaw
@Tpt

Packaging

• Bump MSRV to Rust 1.83. #5531
• Bump minimum supported quote version to 1.0.37. #5531
• Bump supported GraalPy version to 25.0. #5542
• Drop memoffset dependency. #5545
• Support for free-threaded Python is now opt-out rather than opt-in. #5564
• Bump target-lexicon dependency to 0.13.3. #5571
• Drop indoc and unindent dependencies. #5608

Added

• Add __init__ support in #[pymethods]. #4951
• Expose PySuper on PyPy, GraalPy and ABI3 #4951
• Add PyString::from_fmt and py_format! macro. #5199
• Add #[pyclass(new = "from_fields")] option. #5421
• Add pyo3::buffer::PyUntypedBuffer, a type-erased form of PyBuffer<T>. #5458
• Add PyBytes::new_with_writer #5517
• Add PyClass::NAME. #5579
• Add pyo3_build_config::add_libpython_rpath_link_args. #5624
• Add PyBackedStr::clone_ref and PyBackedBytes::clone_ref methods. #5654
• Add PyCapsule::new_with_pointer and PyCapsule::new_with_pointer_and_destructor for creating capsules with raw pointers. #5689
• Add #[deleter] attribute to implement property deleters in #[methods]. #5699
• Add IntoPyObject and FromPyObject implementations for uuid::NonNilUuid. #5707
• Add PyBackedStr::as_str and PyBackedStr::as_py_str methods. #5723
• Add support for subclassing native types (PyDict, exceptions, ...) when building for abi3 on Python 3.12+. #5733
• Add support for subclassing PyList when building for Python 3.12+. #5734
• FFI definitions:
  • Add FFI definitions PyEval_GetFrameBuiltins, PyEval_GetFrameGlobals and PyEval_GetFrameLocals on Python 3.13 and up. #5590
  • Add FFI definitions PyObject_New, PyObject_NewVar, PyObject_GC_Resize, PyObject_GC_New, and PyObject_GC_NewVar. #5591
  • Added FFI definitions and an unsafe Rust API wrapping Py_BEGIN_CRITICAL_SECTION_MUTEX and Py_BEGIN_CRITICAL_SECTION_MUTEX2. #5642
  • Add FFI definition PyDict_GetItemStringRef on Python 3.13 and up. #5659
  • Add FFI definition PyIter_NextItem on Python 3.14 and up, and compat::PyIter_NextItem for older versions. #5661
  • Add FFI definitions PyThreadState_GetInterpreter and PyThreadState_GetID on Python 3.9+, PyThreadState_EnterTracing and PyThreadState_LeaveTracing on Python 3.11+, PyThreadState_GetUnchecked on Python 3.13+, and compat::PyThreadState_GetUnchecked. #5711
  • Add FFI definitions PyImport_ImportModuleAttr and PyImport_ImportModuleAttrString on Python 3.14+. #5737
  • Add FFI definitions for the PyABIInfo and PyModExport APIs available in Python 3.15. #5746
• experimental-inspect:
  • Emit base classes. #5331
  • Emit @typing.final on final classes. #5552
  • Generate nested classes for complex enums. #5708
  • Emit async keyword for async functions. #5731

Changed

• Call sys.unraisablehook instead of PyErr_Print if panicking on null FFI pointer in Bound, Borrowed and Py constructors. #5496
• Use PEP-489 multi-phase initialization for #[pymodule]. #5525
• Deprecate implicit by-value implementation of FromPyObject for #[pyclass]. #5550
• Deprecate PyTypeInfo::NAME and PyTypeInfo::MODULE. #5579
• Deprecate Py<T>::from_{owned,borrowed}[or_{err,opt}] constructors from raw pointer. #5585
• Deprecate FFI definitions PyEval_AcquireLock and PyEval_ReleaseLock. #5590
• Relax 'py: 'a bound in Py::extract. #5594
• Add a T: PyTypeCheck bound to the IntoPyObject implementations on Bound<T>, Borrowed<T> and Py<T>. #5640
• The with_critical_section and with_critical_section2 functions are moved to pyo3::sync::critical_section. #5642
• Use PyIter_NextItem in PyIterator::next implementation. #5661
• IntoPyObject for simple enums now uses a singleton value, allowing identity (python is) comparisons. #5665
• Allow any Sequence[int] in FromPyObject on Cow<[u8]> and change the error type to PyErr. #5667
• async pymethods now borrow self only for the duration of awaiting the future, not the entire method call. #5684
• Change CastError formatted message to directly describe the "is not an instance of" failure condition. #5693
• Add #[inline] hints to many methods on PyBackedStr. #5723
• Remove redundant internal counters from BoundSetIterator and BoundFrozenSetIterator. #5725
• Implement PyIterator::size_hint on abi3 builds (previously was only on unlimited API builds). #5727
• Deprecate FFI definition PyImport_ImportModuleNoBlock (deprecated in Python 3.13). #5737
• #[new] can now return arbitrary Python objects. #5739
• experimental-inspect:
  • Introduce TypeHint and make use of it to encode type hint annotations. #5438
  • Rename PyType{Info,Check}::TYPE_INFO into PyType{Info,Check}::TYPE_HINT. #5438 #5619 #5641
  • Fill annotations on function arguments and return values for all types supported natively by PyO3. #5634 #5637 #5639
  • Use _typeshed.Incomplete instead of typing.Any as default type hint, to make it easier to spot incomplete trait implementations. #5744
  • Use general Python expression syntax for type hints. #5671

Removed

• Remove all functionality deprecated in PyO3 0.25 and 0.26. #5740
• FFI definitions:
  • Remove FFI definition PyEval_GetCallStats (removed from CPython in Python 3.7). #5590
  • Remove FFI definitions PyEval_AcquireLock and PyEval_ReleaseLock on Python 3.13 and up. #5590
  • Remove private FFI definitions _PyObject_New, _PyObject_NewVar, _PyObject_GC_Resize, _PyObject_GC_New, and _PyObject_GC_NewVar. #5591
  • Remove private FFI definitions _PyDict_SetItem_KnownHash, _PyDict_Next, _PyDict_NewPresized, _PyDict_Contains_KnownHash, and _PyDict_Contains. #5659
  • Remove private FFI definitions _PyFrameEvalFunction, _PyInterpreterState_GetEvalFrameFunc and _PyInterpreterState_SetEvalFrameFunc. #5711
  • Remove private FFI definitions _PyImport_IsInitialized, _PyImport_SetModule, _PyImport_SetModuleString, _PyImport_AcquireLock, _PyImport_ReleaseLock, _PyImport_FindBuiltin, _PyImport_FindExtensionObject, _PyImport_FixupBuiltin, and _PyImport_FixupExtensionObject. #5737

Fixed

• Fix PyModuleMethods::add_submodule() to use the last segment of the submodule name as the attribute name on the parent module instead of using the full name. #5375
• Link with libpython for Cygwin extension modules. #5571
• Link against the limited API DLL for Cygwin when abi3 is used. #5574
• Handle errors in PyIterator when calling size_hint #5604
• Link with libpython for iOS extension modules. #5605
• Correct IntoPyObject output type of PyBackedStr to be PyString, not PyAny. #5655
• Fix async functions to return None rather than empty tuple (). #5685
• Fix compile error when using references to #[pyclass] types (e.g. &MyClass) as arguments to async #[pyfunction]s. #5725
• FFI definitions:
  • Fix FFI definition PyMemberDescrObject.d_member to use PyMemberDef for Python 3.11+ (was incorrectly PyGetSetDef). #5647
  • Mark FFI definition PyThreadState_GetFrame available with abi3 in 3.10+. #5711
  • Fix FFI definition PyImport_GetModule on PyPy. #5737
• experimental-inspect:
  • fix __new__ return type to be the built object type and not None. #5555
  • fix imports of decorators. #5618
  • fix the return type annotation of PyResult<()> (must be None and not tuple) #5674

This patch contains very minor fixes for the PyO3 0.27 series:

• Workaround a rustc 1.92+ crash compiling PyO3 with both debug assertions and optimizations enabled.
• Fix runtime crash when subclassing dicts on PyPy and GraalPy.

There are also a number of documentation improvements applied across the codebase.

Thank you to the following contributors for the improvements:

@davidhewitt
@dependabot[bot]
@MusicalNinjaDad
@pkalivas
@tpoliaw
@Tpt

Changed

• Disable subclassing PyDict on GraalPy (unsupported for now, may crash at runtime). #5653

Fixed

• Fix crash when compiling on Rust 1.92+ with both debug assertions and optimizations enabled. #5638
• Fix FFI definition of PyDictObject on PyPy. #5653

This release fixes a clippy lint regression in PyO3 0.27.0, and exposes the PySendResult type (the return value from Bound<PyIterator>::send).

Thank you to the following contributors for the improvements:

@alex
@davidhewitt
@reaperhulk
@tpoliaw

Fixed

• Fix clippy:declare_interior_mutable_const warning from #[pyfunction]. #5538
• Expose pyo3::types::PySendResult in public API. #5539

This release is the first PyO3 release to be tested against Python 3.14.0 final. There are no significant changes to 3.14 support since PyO3 0.26 which was tested against the 3.14 release candidates.

Support for PyPy 3.9 and PyPy 3.10 (both no longer supported upstream) has been dropped.

The FromPyObject trait has been reworked in a similar fashion to the IntoPyObject trait introduced in PyO3 0.23. This has established a performant and flexible implementation of both these traits and no further changes to the traits are anticipated in the future. Thank you for the patience upgrading through these incremental improvements at the core of PyO3.

The .downcast() family of functions are now deprecated in favour of the .cast() family of functions, which are an incremental improvement to API usability and to error messages on failed conversions.

Operations on the PyCapsule type have been changed without deprecation to fix some issues with lifetimes of return values (in .name() and .reference() specifically). The capsule API now also encourages checking of capsule names, which is one of the few defences available to protect the validity of casting data read by the capsule API.

There are also many other incremental improvements, bug fixes and smaller features.

Please consult the migration guide for help upgrading.

Thank you to everyone who contributed code, documentation, design ideas, bug reports, and feedback. The following contributors' commits are included in this release:

@alex
@altendky
@bazaah
@bschoenmaeckers
@crepererum
@davidhewitt
@dependabot[bot]
@elbaro
@Icxolu
@jqnatividad
@mbrobbel
@NilsIrl
@rvben
@sanders41
@tdyas
@Tpt
@vvsagar

Packaging

• Extend range of supported versions of hashbrown optional dependency to include version 0.16. #5428
• Bump optional num-bigint dependency minimum version to 0.4.4. #5471
• Test against Python 3.14 final release. #5499
• Drop support for PyPy 3.9 and 3.10. #5516
• Provide a better error message when building an outdated PyO3 for a too-new Python version. #5519

Added

• Add FromPyObjectOwned as convenient trait bound for FromPyObject when the data is not borrowed from Python. #4390
• Add Borrowed::extract, same as PyAnyMethods::extract, but does not restrict the lifetime by deref. #4390
• experimental-inspect: basic support for #[derive(IntoPyObject)] (no struct fields support yet). #5365
• experimental-inspect: support #[pyo3(get, set)] and #[pyclass(get_all, set_all)]. #5370
• Add PyTypeCheck::classinfo_object that returns an object that can be used as parameter in isinstance or issubclass. #5387
• Implement PyTypeInfo on datetime.* types even when the limited API is enabled. #5388
• Implement PyTypeInfo on PyIterator, PyMapping and PySequence. #5402
• Implement PyTypeInfo on PyCode when using the stable ABI. #5403
• Implement PyTypeInfo on PyWeakrefReference when using the stable ABI. #5404
• Add pyo3::sync::RwLockExt trait, analogous to pyo3::sync::MutexExt for readwrite locks. #5435
• Add PyString::from_bytes. #5437
• Implement AsRef<[u8]> for PyBytes. #5445
• Add CastError and CastIntoError. #5468
• Add PyCapsuleMethods::pointer_checked and PyCapsuleMethods::is_valid_checked. #5474
• Add Borrowed::cast, Borrowed::cast_exact and Borrowed::cast_unchecked. #5475
• Add conversions for jiff::civil::ISOWeekDate. #5478
• Add conversions for &Cstr, Cstring and Cow<Cstr>. #5482
• add #[pyclass(skip_from_py_object)] option, to opt-out of the FromPyObject: PyClass + Clone blanket impl. #5488
• Add PyErr::add_note. #5489
• Add FromPyObject impl for Cow<Path> & Cow<OsStr>. #5497
• Add #[pyclass(from_py_object)] pyclass option, to opt-in to the extraction of pyclasses by value (requires Clone). #5506

Changed

• Rework FromPyObject trait for flexibility and performance: #4390
  • Add a second lifetime to FromPyObject, to allow borrowing data from Python objects (e.g. &str from Python str).
  • Replace extract_bound with extract, which takes Borrowed<'a, 'py, PyAny>.
• Optimize FromPyObject implementations for Vec<u8> and [u8; N] from bytes and bytearray. #5244
• Deprecate #[pyfn] attribute. #5384
• Fetch type name dynamically on cast errors instead of using PyTypeCheck::NAME. #5387
• Deprecate PyTypeCheck::NAME in favour of PyTypeCheck::classinfo_object which provides the type information at runtime. #5387
• PyClassGuard(Mut) and PyRef(Mut) extraction now returns an opaque Rust error #5413
• Fetch type name dynamically when exporting types implementing PyTypeInfo with #[pymodule_use]. #5414
• Improve Debug representation of PyBuffer<T>. #5442
• experimental-inspect: change the way introspection data is emitted in the binaries to avoid a pointer indirection and simplify parsing. #5450
• Optimize Py<T>::drop for the case when attached to the Python interpreter. #5454
• Replace DowncastError and DowncastIntoError with CastError and CastIntoError. #5468
• Enable fast-path for 128-bit integer conversions on GraalPy. #5471
• Deprecate PyAnyMethods::downcast functions in favour of Bound::cast functions. #5472
• Make PyTypeCheck an unsafe trait. #5473
• Deprecate unchecked PyCapsuleMethods: pointer(), reference(), and is_valid(). #5474
• Reduce lifetime of return value in PyCapsuleMethods::reference. #5474
• PyCapsuleMethods::name now returns CapsuleName wrapper instead of &CStr. #5474
• Deprecate import_exception_bound in favour of import_exception. #5480
• PyList::get_item_unchecked, PyTuple::get_item_unchecked, and PyTuple::get_borrowed_item_unchecked no longer check for null values at the provided index. #5494
• Allow converting naive datetime into chrono DateTime<Local>. #5507

Removed

• Removed FromPyObjectBound trait. #4390

Fixed

• Fix compilation failure on wasm32-wasip2. #5368
• Fix OsStr conversion for non-utf8 strings on Windows. #5444
• Fix issue with cargo vendor caused by gitignored build artifact emscripten/pybuilddir.txt. #5456
• Stop leaking PyMethodDef instances inside #[pyfunction] macro generated code. #5459
• Don't export definition of FFI struct PyObjectObFlagsAndRefcnt on 32-bit Python 3.14 (doesn't exist). #5499
• Fix failure to build for abi3 interpreters on Windows using maturin's built-in sysconfig in combination with the generate-import-lib feature. #5503
• Fix FFI definitions PyModule_ExecDef and PyModule_FromDefAndSpec2 on PyPy. #5529

Packaging

• Bump hashbrown dependency to 0.15. #5152
• Update MSRV to 1.74. #5171
• Set the same maximum supported version for alternative interpreters as for CPython. #5192
• Add optional bytes dependency to add conversions for bytes::Bytes. #5252
• Publish new crate pyo3-introspection to pair with the experimental-inspect feature. #5300
• The PYO3_BUILD_EXTENSION_MODULE now causes the same effect as the extension-module feature. Eventually we expect maturin and setuptools-rust to set this environment variable automatically. Users with their own build systems will need to do the same. #5343

Added

• Add #[pyo3(warn(message = "...", category = ...))] attribute for automatic warnings generation for #[pyfunction] and #[pymethods]. #4364
• Add PyMutex, available on Python 3.13 and newer. #4523
• Add FFI definition PyMutex_IsLocked, available on Python 3.14 and newer. #4523
• Add PyString::from_encoded_object. #5017
• experimental-inspect: add basic input type annotations. #5089
• Add FFI function definitions for PyFrameObject from CPython 3.13. #5154
• experimental-inspect: tag modules created using #[pymodule] or #[pymodule_init] functions as incomplete. #5207
• experimental-inspect: add basic return type support. #5208
• Add PyCode::compile and PyCodeMethods::run to create and execute code objects. #5217
• Add PyOnceLock type for thread-safe single-initialization. #5223
• Add PyClassGuard(Mut) pyclass holders. In the future they will replace PyRef(Mut). #5233
• experimental-inspect: allow annotations in #[pyo3(signature)] signature attribute. #5241
• Implement MutexExt for parking_lot's/lock_api ReentrantMutex. #5258
• experimental-inspect: support class associated constants. #5272
• Add Bound::cast family of functions superseding the PyAnyMethods::downcast family. #5289
• Add FFI definitions Py_Version and Py_IsFinalizing. #5317
• experimental-inspect: add output type annotation for #[pyclass]. #5320
• experimental-inspect: support #[pyclass(eq, eq_int, ord, hash, str)]. #5338
• experimental-inspect: add basic support for #[derive(FromPyObject)] (no struct fields support yet). #5339
• Add Python::try_attach. #5342

Changed

• Use Py_TPFLAGS_DISALLOW_INSTANTIATION instead of a __new__ which always fails for a #[pyclass] without a #[new] on Python 3.10 and up. #4568
• PyModule::from_code now defaults file_name to <string> if empty. #4777
• Deprecate PyString::from_object in favour of PyString::from_encoded_object. #5017
• When building with abi3 for a Python version newer than pyo3 supports, automatically fall back to an abi3 build for the latest supported version. #5144
• Change is_instance_of trait bound from PyTypeInfo to PyTypeCheck. #5146
• Many PyO3 proc macros now report multiple errors instead of only the first one. #5159
• Change MutexExt return type to be an associated type. #5201
• Use PyCallArgs for Py::call and friends so they're equivalent to their Bound counterpart. #5206
• Rename Python::with_gil to Python::attach. #5209
• Rename Python::allow_threads to Python::detach #5221
• Deprecate GILOnceCell type in favour of PyOnceLock. #5223
• Rename pyo3::prepare_freethreaded_python to Python::initialize. #5247
• Convert PyMemoryError into/from io::ErrorKind::OutOfMemory. #5256
• Deprecate GILProtected. #5285
• Move #[pyclass] docstring formatting from import time to compile time. #5286
• Python::attach will now panic if the Python interpreter is in the process of shutting down. #5317
• Add fast-path to PyTypeInfo::type_object for #[pyclass] types. #5324
• Deprecate PyObject type alias for Py<PyAny>. #5325
• Rename Python::with_gil_unchecked to Python::attach_unchecked. #5340
• Rename Python::assume_gil_acquired to Python::assume_attached. #5354

Removed

• Remove FFI definition of internals of PyFrameObject. #5154
• Remove Eq and PartialEq implementations on PyGetSetDef FFI definition. #5196
• Remove private FFI definitions _Py_IsCoreInitialized and _Py_InitializeMain. #5317

Fixed

• Use critical section in PyByteArray::to_vec on freethreaded build to replicate GIL-enabled "soundness". #4742
• Fix precision loss when converting bigdecimal into Python. #5198
• Don't treat win7 target as a cross-compilation. #5210
• WASM targets no longer require exception handling support for Python < 3.14. #5239
• Fix segfault when dropping PyBuffer<T> after the Python interpreter has been finalized. #5242
• experimental-inspect: better automated imports generation. #5251
• experimental-inspect: fix introspection of __richcmp__, __concat__, __repeat__, __inplace_concat__ and __inplace_repeat__. #5273
• fixed a leaked borrow, when converting a mutable sub class into a frozen base class using PyRef::into_super #5281
• Fix FFI definition Py_Exit (never returns, was () return value, now !). #5317
• experimental-inspect: fix handling of module members gated behind #[cfg(...)] attributes. #5318

Packaging

• Add support for Windows on ARM64. #5145
• Add chrono-local feature for optional conversions for chrono's Local timezone & DateTime<Local> instances. #5174

Added

• Add FFI definition PyBytes_AS_STRING. #5121
• Add support for module associated consts introspection. #5150

Changed

• Enable "vectorcall" FFI definitions on GraalPy. #5121
• Use Py_Is function on GraalPy #5121

Fixed

• Report a better compile error for async declarations when not using experimental-async feature. #5156
• Fix implementation of FromPyObject for uuid::Uuid on big-endian architectures. #5161
• Fix segmentation faults on 32-bit x86 with Python 3.14. #5180

Packaging

• Support Python 3.14.0b1. #4811
• Bump supported GraalPy version to 24.2. #5116
• Add optional bigdecimal dependency to add conversions for bigdecimal::BigDecimal. #5011
• Add optional time dependency to add conversions for time types. #5057
• Remove cfg-if dependency. #5110
• Add optional ordered_float dependency to add conversions for ordered_float::NotNan and ordered_float::OrderedFloat. #5114

Added

• Add initial type stub generation to the experimental-inspect feature. #3977
• Add #[pyclass(generic)] option to support runtime generic typing. #4926
• Implement OnceExt & MutexExt for parking_lot & lock_api. Use the new extension traits by enabling the arc_lock, lock_api, or parking_lot cargo features. #5044
• Implement From/Into for Borrowed<T> -> Py<T>. #5054
• Add PyTzInfo constructors. #5055
• Add FFI definition PY_INVALID_STACK_EFFECT. #5064
• Implement AsRef<Py<PyAny>> for Py<T>, Bound<T> and Borrowed<T>. #5071
• Add FFI definition PyModule_Add and compat::PyModule_Add. #5085
• Add FFI definitions Py_HashBuffer, Py_HashPointer, and PyObject_GenericHash. #5086
• Support #[pymodule_export] on const items in declarative modules. #5096
• Add #[pyclass(immutable_type)] option (on Python 3.14+ with abi3, or 3.10+ otherwise) for immutable type objects. #5101
• Support #[pyo3(rename_all)] support on #[derive(IntoPyObject)]. #5112
• Add PyRange wrapper. #5117

Changed

• Enable use of datetime types with abi3 feature enabled. #4970
• Deprecate timezone_utc in favor of PyTzInfo::utc. #5055
• Reduce visibility of some CPython implementation details: #5064
  • The FFI definition PyCodeObject is now an opaque struct on all Python versions.
  • The FFI definition PyFutureFeatures is now only defined up until Python 3.10 (it was present in CPython headers but unused in 3.11 and 3.12).
• Change PyAnyMethods::is to take other: &Bound<T>. #5071
• Change Py::is to take other: &Py<T>. #5071
• Change PyVisit::call to take T: Into<Option<&Py<T>>>. #5071
• Expose PyDateTime_DATE_GET_TZINFO and PyDateTime_TIME_GET_TZINFO on PyPy 3.10 and later. #5079
• Add #[track_caller] to with_gil and with_gil_unchecked. #5109
• Use std::thread::park() instead of libc::pause() or sleep(9999999). #5115

Removed

• Remove all functionality deprecated in PyO3 0.23. #4982
• Remove deprecated IntoPy and ToPyObject traits. #5010
• Remove private types from pyo3-ffi (i.e. starting with _Py) which are not referenced by public APIs: _PyLocalMonitors, _Py_GlobalMonitors, _PyCoCached, _PyCoLineInstrumentationData, _PyCoMonitoringData, _PyCompilerSrcLocation, _PyErr_StackItem. #5064
• Remove FFI definition PyCode_GetNumFree (PyO3 cannot support it due to knowledge of the code object). #5064
• Remove AsPyPointer trait. #5071
• Remove support for the deprecated string form of from_py_with. #5097
• Remove FFI definitions of private static variables: _PyMethodWrapper_Type, _PyCoroWrapper_Type, _PyImport_FrozenBootstrap, _PyImport_FrozenStdlib, _PyImport_FrozenTest, _PyManagedBuffer_Type, _PySet_Dummy, _PyWeakref_ProxyType, and _PyWeakref_CallableProxyType. #5105
• Remove FFI definitions PyASCIIObjectState, PyUnicode_IS_ASCII, PyUnicode_IS_COMPACT, and PyUnicode_IS_COMPACT_ASCII on Python 3.14 and newer. #5133

Fixed

• Correctly pick up the shared state for conda-based Python installation when reading information from sysconfigdata. #5037
• Fix compile failure with #[derive(IntoPyObject, FromPyObject)] when using #[pyo3()] options recognised by only one of the two derives. #5070
• Fix various compile errors from missing FFI definitions using certain feature combinations on PyPy and GraalPy. #5091
• Fallback on backports.zoneinfo for python <3.9 when converting timezones into python. #5120

Fixed

• Fix unused_imports lint of #[pyfunction] and #[pymethods] expanded in macro_rules context. #5030
• Fix size of PyCodeObject::_co_instrumentation_version ffi struct member on Python 3.13 for systems where uintptr_t is not 64 bits. #5048
• Fix struct-type complex enum variant fields incorrectly exposing raw identifiers as r#ident in Python bindings. #5050

Added

• Add abi3-py313 feature. #4969
• Add PyAnyMethods::getattr_opt. #4978
• Add PyInt::new constructor for all supported number types (i32, u32, i64, u64, isize, usize). #4984
• Add pyo3::sync::with_critical_section2. #4992
• Implement PyCallArgs for Borrowed<'_, 'py, PyTuple>, &Bound<'py, PyTuple>, and &Py<PyTuple>. #5013

Fixed

• Fix is_type_of for native types not using same specialized check as is_type_of_bound. #4981
• Fix Probe class naming issue with #[pymethods]. #4988
• Fix compile failure with required #[pyfunction] arguments taking Option<&str> and Option<&T> (for #[pyclass] types). #5002
• Fix PyString::from_object causing of bounds reads with encoding and errors parameters which are not nul-terminated. #5008
• Fix compile error when additional options follow after crate for #[pyfunction]. #5015

Packaging

• Add supported CPython/PyPy versions to cargo package metadata. #4756
• Bump target-lexicon dependency to 0.13. #4822
• Add optional jiff dependency to add conversions for jiff datetime types. #4823
• Add optional uuid dependency to add conversions for uuid::Uuid. #4864
• Bump minimum supported inventory version to 0.3.5. #4954

Added

• Add PyIterator::send method to allow sending values into a python generator. #4746
• Add PyCallArgs trait for passing arguments into the Python calling protocol. This enabled using a faster calling convention for certain types, improving performance. #4768
• Add #[pyo3(default = ...'] option for #[derive(FromPyObject)] to set a default value for extracted fields of named structs. #4829
• Add #[pyo3(into_py_with = ...)] option for #[derive(IntoPyObject, IntoPyObjectRef)]. #4850
• Add FFI definitions PyThreadState_GetFrame and PyFrame_GetBack. #4866
• Optimize last for BoundListIterator, BoundTupleIterator and BorrowedTupleIterator. #4878
• Optimize Iterator::count() for PyDict, PyList, PyTuple & PySet. #4878
• Optimize nth, nth_back, advance_by and advance_back_by for BoundTupleIterator #4897
• Add support for types.GenericAlias as pyo3::types::PyGenericAlias. #4917
• Add MutextExt trait to help avoid deadlocks with the GIL while locking a std::sync::Mutex. #4934
• Add #[pyo3(rename_all = "...")] option for #[derive(FromPyObject)]. #4941

Changed

• Optimize nth, nth_back, advance_by and advance_back_by for BoundListIterator. #4810
• Use DerefToPyAny in blanket implementations of From<Py<T>> and From<Bound<'py, T>> for PyObject. #4593
• Map io::ErrorKind::IsADirectory/NotADirectory to the corresponding Python exception on Rust 1.83+. #4747
• PyAnyMethods::call and friends now require PyCallArgs for their positional arguments. #4768
• Expose FFI definitions for PyObject_Vectorcall(Method) on the stable abi on 3.12+. #4853
• #[pyo3(from_py_with = ...)] now take a path rather than a string literal #4860
• Format Python traceback in impl Debug for PyErr. #4900
• Convert PathBuf & Path into Python pathlib.Path instead of PyString. #4925
• Relax parsing of exotic Python versions. #4949
• PyO3 threads now hang instead of pthread_exit trying to acquire the GIL when the interpreter is shutting down. This mimics the Python 3.14 behavior and avoids undefined behavior and crashes. #4874

Removed

• Remove implementations of Deref for PyAny and other "native" types. #4593
• Remove implicit default of trailing optional arguments (see #2935) #4729
• Remove the deprecated implicit eq fallback for simple enums. #4730

Fixed

• Correct FFI definition of PyIter_Send to return a PySendResult. #4746
• Fix a thread safety issue in the runtime borrow checker used by mutable pyclass instances on the free-threaded build. #4948

Packaging

• Add support for PyPy3.11 #4760

Fixed

• Fix thread-unsafe implementation of freelist pyclasses on the free-threaded build. #4902
• Re-enable a workaround for situations where CPython incorrectly does not add __builtins__ to __globals__ in code executed by Python::py_run (was removed in PyO3 0.23.0). #4921

Added

• Add PyList::locked_for_each, which uses a critical section to lock the list on the free-threaded build. #4789
• Add pyo3_build_config::add_python_framework_link_args build script API to set rpath when using macOS system Python. #4833

Changed

• Use datetime.fold to distinguish ambiguous datetimes when converting to and from chrono::DateTime<Tz> (rather than erroring). #4791
• Optimize PyList iteration on the free-threaded build. #4789

Fixed

• Fix unnecessary internal py.allow_threads GIL-switch when attempting to access contents of a PyErr which originated from Python (could lead to unintended deadlocks). #4766
• Fix thread-unsafe access of dict internals in BoundDictIterator on the free-threaded build. #4788

• Fix unnecessary critical sections in BoundDictIterator on the free-threaded build. #4788

• Fix time-of-check to time-of-use issues with list iteration on the free-threaded build. #4789
• Fix chrono::DateTime<Tz> to-Python conversion when Tz is chrono_tz::Tz. #4790
• Fix #[pyclass] not being able to be named Probe. #4794
• Fix not treating cross-compilation from x64 to aarch64 on Windows as a cross-compile. #4800
• Fix missing struct fields on GraalPy when subclassing builtin classes. #4802
• Fix generating import lib for PyPy when abi3 feature is enabled. #4806
• Fix generating import lib for python3.13t when abi3 feature is enabled. #4808
• Fix compile failure for raw identifiers like r#box in derive(FromPyObject). #4814
• Fix compile failure for #[pyclass] enum variants with more than 12 fields. #4832

Packaging

• Bump optional python3-dll-a dependency to 0.2.11. #4749

Fixed

• Fix unresolved symbol link failures on Windows when compiling for Python 3.13t with abi3 features enabled. #4733
• Fix unresolved symbol link failures on Windows when compiling for Python 3.13t using the generate-import-lib feature. #4749
• Fix compile-time regression in PyO3 0.23.0 where changing PYO3_CONFIG_FILE would not reconfigure PyO3 for the new interpreter. #4758

Added

• Add IntoPyObjectExt trait. #4708

Fixed

• Fix compile failures when building for free-threaded Python when the abi3 or abi3-pyxx features are enabled. #4719
• Fix ambiguous_associated_items lint error in #[pyclass] and #[derive(IntoPyObject)] macros. #4725

Re-release of 0.23.0 with fixes to docs.rs build.

Packaging

• Drop support for PyPy 3.7 and 3.8. #4582
• Extend range of supported versions of hashbrown optional dependency to include version 0.15. #4604
• Bump minimum version of eyre optional dependency to 0.6.8. #4617
• Bump minimum version of hashbrown optional dependency to 0.14.5. #4617
• Bump minimum version of indexmap optional dependency to 2.5.0. #4617
• Bump minimum version of num-complex optional dependency to 0.4.6. #4617
• Bump minimum version of chrono-tz optional dependency to 0.10. #4617
• Support free-threaded Python 3.13t. #4588

Added

• Add IntoPyObject (fallible) conversion trait to convert from Rust to Python values. #4060
• Add #[pyclass(str="<format string>")] option to generate __str__ based on a Display implementation or format string. #4233
• Implement PartialEq for Bound<'py, PyInt> with u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128 and isize. #4317
• Implement PartialEq<f64> and PartialEq<f32> for Bound<'py, PyFloat>. #4348
• Add as_super and into_super methods for Bound<T: PyClass>. #4351
• Add FFI definitions PyCFunctionFast and PyCFunctionFastWithKeywords #4415
• Add FFI definitions for PyMutex on Python 3.13 and newer. #4421
• Add PyDict::locked_for_each to iterate efficiently on freethreaded Python. #4439
• Add FFI definitions PyObject_GetOptionalAttr, PyObject_GetOptionalAttrString, PyObject_HasAttrWithError, PyObject_HasAttrStringWithError, Py_CONSTANT_* constants, Py_GetConstant, Py_GetConstantBorrowed, and PyType_GetModuleByDef on Python 3.13 and newer. #4447
• Add FFI definitions for the Python critical section API available on Python 3.13 and newer. #4477
• Add derive macro for IntoPyObject. #4495
• Add Borrowed::as_ptr. #4520
• Add FFI definition for PyImport_AddModuleRef. #4529
• Add PyAnyMethods::try_iter. #4553
• Add pyo3::sync::with_critical_section, a wrapper around the Python Critical Section API added in Python 3.13. #4587
• Add #[pymodule(gil_used = false)] option to declare that a module supports the free-threaded build. #4588
• Add PyModule::gil_used method to declare that a module supports the free-threaded build. #4588
• Add FFI definition PyDateTime_CAPSULE_NAME. #4634
• Add PyMappingProxy type to represent the mappingproxy Python class. #4644
• Add FFI definitions PyList_Extend and PyList_Clear. #4667
• Add derive macro for IntoPyObjectRef. #4674
• Add pyo3::sync::OnceExt and pyo3::sync::OnceLockExt traits. #4676

Changed

• Prefer IntoPyObject over IntoPy<Py<PyAny>>> for #[pyfunction] and #[pymethods] return types. #4060
• Report multiple errors from #[pyclass] and #[pyo3(..)] attributes. #4243
• Nested declarative #[pymodule] are automatically treated as submodules (no PyInit_ entrypoint is created). #4308
• Deprecate PyAnyMethods::is_ellipsis (Py::is_ellipsis was deprecated in PyO3 0.20). #4322
• Deprecate PyLong in favor of PyInt. #4347
• Rename IntoPyDict::into_py_dict_bound to IntoPyDict::into_py_dict. #4388
• PyModule::from_code now expects &CStr as arguments instead of &str. #4404
• Use "fastcall" Python calling convention for #[pyfunction]s when compiling on abi3 for Python 3.10 and up. #4415
• Remove Copy and Clone from PyObject struct FFI definition. #4434
• Python::eval and Python::run now take a &CStr instead of &str. #4435
• Deprecate IPowModulo, PyClassAttributeDef, PyGetterDef, PyMethodDef, PyMethodDefType, and PySetterDef from PyO3's public API. #4441
• IntoPyObject impls for Vec<u8>, &[u8], [u8; N], Cow<[u8]> and SmallVec<[u8; N]> now convert into Python bytes rather than a list of integers. #4442
• Emit a compile-time error when attempting to subclass a class that doesn't allow subclassing. #4453
• IntoPyDict::into_py_dict is now fallible due to IntoPyObject migration. #4493
• The abi3 feature will now override config files provided via PYO3_BUILD_CONFIG. #4497
• Disable the GILProtected struct on free-threaded Python. #4504
• Updated FFI definitions for functions and struct fields that have been deprecated or removed from CPython. #4534
• Disable PyListMethods::get_item_unchecked on free-threaded Python. #4539
• Add GILOnceCell::import. #4542
• Deprecate PyAnyMethods::iter in favour of PyAnyMethods::try_iter. #4553
• The #[pyclass] macro now requires a types to be Sync. (Except for #[pyclass(unsendable)] types). #4566
• PyList::new and PyTuple::new are now fallible due to IntoPyObject migration. #4580
• PyErr::matches is now fallible due to IntoPyObject migration. #4595
• Deprecate ToPyObject in favour of IntoPyObject #4595
• Deprecate PyWeakrefMethods::get_option. #4597
• Seal PyWeakrefMethods trait. #4598
• Remove PyNativeTypeInitializer and PyObjectInit from the PyO3 public API. #4611
• Deprecate IntoPy in favor of IntoPyObject #4618
• Eagerly normalize exceptions in PyErr::take() and PyErr::fetch() on Python 3.11 and older. #4655
• Move IntoPy::type_output to IntoPyObject::type_output. #4657
• Change return type of PyMapping::keys, PyMapping::values and PyMapping::items to Bound<'py, PyList> instead of Bound<'py, PySequence>. #4661
• Complex enums now allow field types that either implement IntoPyObject by reference or by value together with Clone. This makes Py<T> available as field type. #4694

Removed

• Remove all functionality deprecated in PyO3 0.20. #4322
• Remove all functionality deprecated in PyO3 0.21. #4323
• Deprecate PyUnicode in favour of PyString. #4370
• Remove deprecated gil-refs feature. #4378
• Remove private FFI definitions _Py_IMMORTAL_REFCNT, _Py_IsImmortal, _Py_TPFLAGS_STATIC_BUILTIN, _Py_Dealloc, _Py_IncRef, _Py_DecRef. #4447
• Remove private FFI definitions _Py_c_sum, _Py_c_diff, _Py_c_neg, _Py_c_prod, _Py_c_quot, _Py_c_pow, _Py_c_abs. #4521
• Remove _borrowed methods of PyWeakRef and PyWeakRefProxy. #4528
• Removed private FFI definition _PyErr_ChainExceptions. #4534

Fixed

• Fix invalid library search path lib_dir when cross-compiling. #4389
• Fix FFI definition Py_Is for PyPy on 3.10 to call the function defined by PyPy. #4447
• Fix compile failure when using #[cfg] attributes for simple enum variants. #4509
• Fix compiler warning for non_snake_case method names inside #[pymethods] generated code. #4567
• Fix compile error with #[derive(FromPyObject)] generic struct with trait bounds. #4645
• Fix compile error for #[classmethod] and #[staticmethod] on magic methods. #4654
• Fix compile warning for unsafe_op_in_unsafe_fn in generated macro code. #4674
• Fix incorrect deprecation warning for #[pyclass] enums with custom __eq__ implementation. #4692
• Fix non_upper_case_globals lint firing for generated __match_args__ on complex enums. #4705

Fixed

• Fix regression in 0.22.4 of naming collision in __clear__ slot and clear method generated code. #4619

Added

• Add FFI definition PyWeakref_GetRef and compat::PyWeakref_GetRef. #4528

Changed

• Deprecate _borrowed methods on PyWeakRef and PyWeakrefProxy (just use the owning forms). #4590

Fixed

• Revert removal of private FFI function _PyLong_NumBits on Python 3.13 and later. #4450
• Fix __traverse__ functions for base classes not being called by subclasses created with #[pyclass(extends = ...)]. #4563
• Fix regression in 0.22.3 failing compiles under #![forbid(unsafe_code)]. #4574
• Fix create_exception macro triggering lint and compile errors due to interaction with gil-refs feature. #4589
• Workaround possible use-after-free in _borrowed methods on PyWeakRef and PyWeakrefProxy by leaking their contents. #4590
• Fix crash calling PyType_GetSlot on static types before Python 3.10. #4599

Added

• Add pyo3::ffi::compat namespace with compatibility shims for C API functions added in recent versions of Python.
• Add FFI definition PyDict_GetItemRef on Python 3.13 and newer, and compat::PyDict_GetItemRef for all versions. #4355
• Add FFI definition PyList_GetItemRef on Python 3.13 and newer, and pyo3_ffi::compat::PyList_GetItemRef for all versions. #4410
• Add FFI definitions compat::Py_NewRef and compat::Py_XNewRef. #4445
• Add FFI definitions compat::PyObject_CallNoArgs and compat::PyObject_CallMethodNoArgs. #4461
• Add GilOnceCell<Py<T>>::clone_ref. #4511

Changed

• Improve error messages for #[pyfunction] defined inside #[pymethods]. #4349
• Improve performance of calls to Python by using the vectorcall calling convention where possible. #4456
• Mention the type name in the exception message when trying to instantiate a class with no constructor defined. #4481

Removed

• Remove private FFI definition _Py_PackageContext. #4420

Fixed

• Fix compile failure in declarative #[pymodule] under presence of #![no_implicit_prelude]. #4328
• Fix use of borrowed reference in PyDict::get_item (unsafe in free-threaded Python). #4355
• Fix #[pyclass(eq)] macro hygiene issues for structs and enums. #4359
• Fix hygiene/span issues of #[pyfunction] and #[pymethods] generated code which affected expansion in macro_rules context. #4382
• Fix unsafe_code lint error in #[pyclass] generated code. #4396
• Fix async functions returning a tuple only returning the first element to Python. #4407
• Fix use of borrowed reference in PyList::get_item (unsafe in free-threaded Python). #4410
• Correct FFI definition PyArg_ParseTupleAndKeywords to take *const *const c_char instead of *mut *mut c_char on Python 3.13 and up. #4420
• Fix a soundness bug with PyClassInitializer: panic if adding subclass to existing instance via PyClassInitializer::from(Py<BaseClass>).add_subclass(SubClass). #4454
• Fix illegal reference counting op inside implementation of __traverse__ handlers. #4479

Packaging

• Require opt-in to freethreaded Python using the UNSAFE_PYO3_BUILD_FREE_THREADED=1 environment variable (it is not yet supported by PyO3). #4327

Changed

• Use FFI function calls for reference counting on all abi3 versions. #4324
• #[pymodule(...)] now directly accepts all relevant #[pyo3(...)] options. #4330

Fixed

• Fix compile failure in declarative #[pymodule] under presence of #![no_implicit_prelude]. #4328
• Fix compile failure due to c-string literals on Rust < 1.79. #4353

Added

• Add #[pyo3(submodule)] option for declarative #[pymodule]s. #4301
• Implement PartialEq<bool> for Bound<'py, PyBool>. #4305

Fixed

• Return NotImplemented instead of raising TypeError from generated equality method when comparing different types. #4287
• Handle full-path #[pyo3::prelude::pymodule] and similar for #[pyclass] and #[pyfunction] in declarative modules. #4288
• Fix 128-bit int regression on big-endian platforms with Python <3.13. #4291
• Stop generating code that will never be covered with declarative modules. #4297
• Fix invalid deprecation warning for trailing optional on #[setter] function. #4304

Packaging

• Update heck dependency to 0.5. #3966
• Extend range of supported versions of chrono-tz optional dependency to include version 0.10. #4061
• Update MSRV to 1.63. #4129
• Add optional num-rational feature to add conversions with Python's fractions.Fraction. #4148
• Support Python 3.13. #4184

Added

• Add PyWeakref, PyWeakrefReference and PyWeakrefProxy. #3835
• Support #[pyclass] on enums that have tuple variants. #4072
• Add support for scientific notation in Decimal conversion. #4079
• Add pyo3_disable_reference_pool conditional compilation flag to avoid the overhead of the global reference pool at the cost of known limitations as explained in the performance section of the guide. #4095
• Add #[pyo3(constructor = (...))] to customize the generated constructors for complex enum variants. #4158
• Add PyType::module, which always matches Python __module__. #4196
• Add PyType::fully_qualified_name which matches the "fully qualified name" defined in PEP 737. #4196
• Add PyTypeMethods::mro and PyTypeMethods::bases. #4197
• Add #[pyclass(ord)] to implement ordering based on PartialOrd. #4202
• Implement ToPyObject and IntoPy<PyObject> for PyBackedStr and PyBackedBytes. #4205
• Add #[pyclass(hash)] option to implement __hash__ in terms of the Hash implementation #4206
• Add #[pyclass(eq)] option to generate __eq__ based on PartialEq, and #[pyclass(eq_int)] for simple enums to implement equality based on their discriminants. #4210
• Implement From<Bound<'py, T>> for PyClassInitializer<T>. #4214
• Add as_super methods to PyRef and PyRefMut for accessing the base class by reference. #4219
• Implement PartialEq<str> for Bound<'py, PyString>. #4245
• Implement PyModuleMethods::filename on PyPy. #4249
• Implement PartialEq<[u8]> for Bound<'py, PyBytes>. #4250
• Add pyo3_ffi::c_str macro to create &'static CStr on Rust versions which don't have 1.77's c"" literals. #4255
• Support bool conversion with numpy 2.0's numpy.bool type #4258
• Add PyAnyMethods::{bitnot, matmul, floor_div, rem, divmod}. #4264

Changed

• Change the type of PySliceIndices::slicelength and the length parameter of PySlice::indices(). #3761
• Deprecate implicit default for trailing optional arguments #4078
• Cloneing pointers into the Python heap has been moved behind the py-clone feature, as it must panic without the GIL being held as a soundness fix. #4095
• Add #[track_caller] to all Py<T>, Bound<'py, T> and Borrowed<'a, 'py, T> methods which can panic. #4098
• Change PyAnyMethods::dir to be fallible and return PyResult<Bound<'py, PyList>> (and similar for PyAny::dir). #4100
• The global reference pool (to track pending reference count decrements) is now initialized lazily to avoid the overhead of taking a mutex upon function entry when the functionality is not actually used. #4178
• Emit error messages when using weakref or dict when compiling for abi3 for Python older than 3.9. #4194
• Change PyType::name to always match Python __name__. #4196
• Remove CPython internal ffi call for complex number including: add, sub, mul, div, neg, abs, pow. Added PyAnyMethods::{abs, pos, neg} #4201
• Deprecate implicit integer comparison for simple enums in favor of #[pyclass(eq_int)]. #4210
• Set the module= attribute of declarative modules' child #[pymodule]s and #[pyclass]es. #4213
• Set the module option for complex enum variants from the value set on the complex enum module. #4228
• Respect the Python "limited API" when building for the abi3 feature on PyPy or GraalPy. #4237
• Optimize code generated by #[pyo3(get)] on #[pyclass] fields. #4254
• PyCFunction::new, PyCFunction::new_with_keywords and PyCFunction::new_closure now take &'static CStr name and doc arguments (previously was &'static str). #4255
• The experimental-declarative-modules feature is now stabilized and available by default. #4257

Fixed

• Fix panic when PYO3_CROSS_LIB_DIR is set to a missing path. #4043
• Fix a compile error when exporting an exception created with create_exception! living in a different Rust module using the declarative-module feature. #4086
• Fix FFI definitions of PY_VECTORCALL_ARGUMENTS_OFFSET and PyVectorcall_NARGS to fix a false-positive assertion. #4104
• Disable PyUnicode_DATA on PyPy: not exposed by PyPy. #4116
• Correctly handle #[pyo3(from_py_with = ...)] attribute on dunder (__magic__) method arguments instead of silently ignoring it. #4117
• Fix a compile error when declaring a standalone function or class method with a Python name that is a Rust keyword. #4226
• Fix declarative modules discarding doc comments on the mod node. #4236
• Fix __dict__ attribute missing for #[pyclass(dict)] instances when building for abi3 on Python 3.9. #4251

Changed

• Deprecate the PySet::empty() gil-ref constructor. #4082

Fixed

• Fix compile error for async fn in #[pymethods] with a &self receiver and more than one additional argument. #4035
• Improve error message for wrong receiver type in __traverse__. #4045
• Fix compile error when exporting a #[pyclass] living in a different Rust module using the experimental-declarative-modules feature. #4054
• Fix missing_docs lint triggering on documented #[pymodule] functions. #4067
• Fix undefined symbol errors for extension modules on AIX (by linking libpython). #4073

Added

• Implement Send and Sync for PyBackedStr and PyBackedBytes. #4007
• Implement Clone, Debug, PartialEq, Eq, PartialOrd, Ord and Hash implementation for PyBackedBytes and PyBackedStr, and Display for PyBackedStr. #4020
• Add import_exception_bound! macro to import exception types without generating GIL Ref functionality for them. #4027

Changed

• Emit deprecation warning for uses of GIL Refs as #[setter] function arguments. #3998
• Add #[inline] hints on many Bound and Borrowed methods. #4024

Fixed

• Handle #[pyo3(from_py_with = "")] in #[setter] methods #3995
• Allow extraction of &Bound in #[setter] methods. #3998
• Fix some uncovered code blocks emitted by #[pymodule], #[pyfunction] and #[pyclass] macros. #4009
• Fix typo in the panic message when a class referenced in pyo3::import_exception! does not exist. #4012
• Fix compile error when using an async #[pymethod] with a receiver and additional arguments. #4015

Added

• Add support for GraalPy (24.0 and up). #3247
• Add PyMemoryView type. #3514
• Allow async fn in for #[pyfunction] and #[pymethods], with the experimental-async feature. #3540 #3588 #3599 #3931
• Implement PyTypeInfo for PyEllipsis, PyNone and PyNotImplemented. #3577
• Support #[pyclass] on enums that have non-unit variants. #3582
• Support chrono feature with abi3 feature. #3664
• FromPyObject, IntoPy<PyObject> and ToPyObject are implemented on std::duration::Duration #3670
• Add PyString::to_cow. Add Py<PyString>::to_str, Py<PyString>::to_cow, and Py<PyString>::to_string_lossy, as ways to access Python string data safely beyond the GIL lifetime. #3677
• Add Bound<T> and Borrowed<T> smart pointers as a new API for accessing Python objects. #3686
• Add PyNativeType::as_borrowed to convert "GIL refs" to the new Bound smart pointer. #3692
• Add FromPyObject::extract_bound method, to migrate FromPyObject implementations to the Bound API. #3706
• Add gil-refs feature to allow continued use of the deprecated GIL Refs APIs. #3707
• Add methods to PyAnyMethods for binary operators (add, sub, etc.) #3712
• Add chrono-tz feature allowing conversion between chrono_tz::Tz and zoneinfo.ZoneInfo #3730
• Add FFI definition PyType_GetModuleByDef. #3734
• Conversion between std::time::SystemTime and datetime.datetime #3736
• Add Py::as_any and Py::into_any. #3785
• Add PyStringMethods::encode_utf8. #3801
• Add PyBackedStr and PyBackedBytes, as alternatives to &str and &bytes where a Python object owns the data. #3802 #3991
• Allow #[pymodule] macro on Rust mod blocks, with the experimental-declarative-modules feature. #3815
• Implement ExactSizeIterator for set and frozenset iterators on abi3 feature. #3849
• Add Py::drop_ref to explicitly drop a `Py`` and immediately decrease the Python reference count if the GIL is already held. #3871
• Allow #[pymodule] macro on single argument functions that take &Bound<'_, PyModule>. #3905
• Implement FromPyObject for Cow<str>. #3928
• Implement Default for GILOnceCell. #3971
• Add PyDictMethods::into_mapping, PyListMethods::into_sequence and PyTupleMethods::into_sequence. #3982

Changed

• PyDict::from_sequence now takes a single argument of type &PyAny (previously took two arguments Python and PyObject). #3532
• Deprecate Py::is_ellipsis and PyAny::is_ellipsis in favour of any.is(py.Ellipsis()). #3577
• Split some PyTypeInfo functionality into new traits HasPyGilRef and PyTypeCheck. #3600
• Deprecate PyTryFrom and PyTryInto traits in favor of any.downcast() via the PyTypeCheck and PyTypeInfo traits. #3601
• Allow async methods to accept &self/&mut self #3609
• FromPyObject for set types now also accept frozenset objects as input. #3632
• FromPyObject for bool now also accepts NumPy's bool_ as input. #3638
• Add AsRefSource associated type to PyNativeType. #3653
• Rename .is_true to .is_truthy on PyAny and Py<PyAny> to clarify that the test is not based on identity with or equality to the True singleton. #3657
• PyType::name is now PyType::qualname whereas PyType::name efficiently accesses the full name which includes the module name. #3660
• The Iter(A)NextOutput types are now deprecated and __(a)next__ can directly return anything which can be converted into Python objects, i.e. awaitables do not need to be wrapped into IterANextOutput or Option any more. Option can still be used as well and returning None will trigger the fast path for __next__, stopping iteration without having to raise a StopIteration exception. #3661
• Implement FromPyObject on chrono::DateTime<Tz> for all Tz, not just FixedOffset and Utc. #3663
• Add lifetime parameter to PyTzInfoAccess trait. For the deprecated gil-ref API, the trait is now implemented for &'py PyTime and &'py PyDateTime instead of PyTime and PyDate. #3679
• Calls to __traverse__ become no-ops for unsendable pyclasses if on the wrong thread, thereby avoiding hard aborts at the cost of potential leakage. #3689
• Include PyNativeType in pyo3::prelude. #3692
• Improve performance of extract::<i64> (and other integer types) by avoiding call to __index__() converting the value to an integer for 3.10+. Gives performance improvement of around 30% for successful extraction. #3742
• Relax bound of FromPyObject for Py<T> to just T: PyTypeCheck. #3776
• PySet and PyFrozenSet iterators now always iterate the equivalent of iter(set). (A "fast path" with no noticeable performance benefit was removed.) #3849
• Move implementations of FromPyObject for &str, Cow<str>, &[u8] and Cow<[u8]> onto a temporary trait FromPyObjectBound when gil-refs feature is deactivated. #3928
• Deprecate GILPool, Python::with_pool, and Python::new_pool. #3947

Removed

• Remove all functionality deprecated in PyO3 0.19. #3603

Fixed

• Match PyPy 7.3.14 in removing PyPy-only symbol Py_MAX_NDIMS in favour of PyBUF_MAX_NDIM. #3757
• Fix segmentation fault using datetime types when an invalid datetime module is on sys.path. #3818
• Fix non_local_definitions lint warning triggered by many PyO3 macros. #3901
• Disable PyCode and PyCode_Type on PyPy: PyCode_Type is not exposed by PyPy. #3934

Prerelease of PyO3 0.21. See the GitHub diff for what changed between 0.21.0-beta.0 and the final release.

Packaging

• Add portable-atomic dependency. #3619
• Check maximum version of Python at build time and for versions not yet supported require opt-in to the abi3 stable ABI by the environment variable PYO3_USE_ABI3_FORWARD_COMPATIBILITY=1. #3821

Fixed

• Use portable-atomic to support platforms without 64-bit atomics. #3619
• Fix compilation failure with either feature enabled without experimental-inspect enabled. #3834

Packaging

• Pin pyo3 and pyo3-ffi dependencies on pyo3-build-config to require the same patch version, i.e. pyo3 0.20.2 requires exactly pyo3-build-config 0.20.2. #3721

Fixed

• Fix compile failure when building pyo3 0.20.0 with latest pyo3-build-config 0.20.X. #3724
• Fix docs.rs build. #3722

Added

• Add optional either feature to add conversions for either::Either<L, R> sum type. #3456
• Add optional smallvec feature to add conversions for smallvec::SmallVec. #3507
• Add take and into_inner methods to GILOnceCell #3556
• #[classmethod] methods can now also receive Py<PyType> as their first argument. #3587
• #[pyfunction(pass_module)] can now also receive Py<PyModule> as their first argument. #3587
• Add traverse method to GILProtected. #3616
• Added abi3-py312 feature #3687

Fixed

• Fix minimum version specification for optional chrono dependency. #3512
• Silenced new clippy::unnecessary_fallible_conversions warning when using a Py<Self> self receiver. #3564

Packaging

• Dual-license PyO3 under either the Apache 2.0 OR the MIT license. This makes the project GPLv2 compatible. #3108
• Update MSRV to Rust 1.56. #3208
• Bump indoc dependency to 2.0 and unindent dependency to 0.2. #3237
• Bump syn dependency to 2.0. #3239
• Drop support for debug builds of Python 3.7. #3387
• Bump chrono optional dependency to require 0.4.25 or newer. #3427
• Support Python 3.12. #3488

Added

• Support __lt__, __le__, __eq__, __ne__, __gt__ and __ge__ in #[pymethods]. #3203
• Add FFI definition Py_GETENV. #3336
• Add as_ptr and into_ptr inherent methods for Py, PyAny, PyRef, and PyRefMut. #3359
• Implement DoubleEndedIterator for PyTupleIterator and PyListIterator. #3366
• Add #[pyclass(rename_all = "...")] option: this allows renaming all getters and setters of a struct, or all variants of an enum. Available renaming rules are: "camelCase", "kebab-case", "lowercase", "PascalCase", "SCREAMING-KEBAB-CASE", "SCREAMING_SNAKE_CASE", "snake_case", "UPPERCASE". #3384
• Add FFI definitions PyObject_GC_IsTracked and PyObject_GC_IsFinalized on Python 3.9 and up (PyPy 3.10 and up). #3403
• Add types for None, Ellipsis, and NotImplemented. #3408
• Add FFI definitions for the Py_mod_multiple_interpreters constant and its possible values. #3494
• Add FFI definitions for PyInterpreterConfig struct, its constants and Py_NewInterpreterFromConfig. #3502

Changed

• Change PySet::discard to return PyResult<bool> (previously returned nothing). #3281
• Optimize implementation of IntoPy for Rust tuples to Python tuples. #3321
• Change PyDict::get_item to no longer suppress arbitrary exceptions (the return type is now PyResult<Option<&PyAny>> instead of Option<&PyAny>), and deprecate PyDict::get_item_with_error. #3330
• Deprecate FFI definitions which are deprecated in Python 3.12. #3336
• AsPyPointer is now an unsafe trait. #3358
• Accept all os.PathLike values in implementation of FromPyObject for PathBuf. #3374
• Add __builtins__ to globals in py.run() and py.eval() if they're missing. #3378
• Optimize implementation of FromPyObject for BigInt and BigUint. #3379
• PyIterator::from_object and PyByteArray::from now take a single argument of type &PyAny (previously took two arguments Python and AsPyPointer). #3389
• Replace AsPyPointer with AsRef<PyAny> as a bound in the blanket implementation of From<&T> for PyObject. #3391
• Replace blanket impl IntoPy<PyObject> for &T where T: AsPyPointer with implementations of impl IntoPy<PyObject> for &PyAny, &T where T: AsRef<PyAny>, and &Py<T>. #3393
• Preserve std::io::Error kind in implementation of From<std::io::IntoInnerError> for PyErr #3396
• Try to select a relevant ErrorKind in implementation of From<PyErr> for OSError subclass. #3397
• Retrieve the original PyErr in implementation of From<std::io::Error> for PyErr if the std::io::Error has been built using a Python exception (previously would create a new exception wrapping the std::io::Error). #3402
• #[pymodule] will now return the same module object on repeated import by the same Python interpreter, on Python 3.9 and up. #3446
• Truncate leap-seconds and warn when converting chrono types to Python datetime types (datetime cannot represent leap-seconds). #3458
• Err returned from #[pyfunction] will now have a non-None __context__ if called from inside a catch block. #3455
• Deprecate undocumented #[__new__] form of #[new] attribute. #3505

Removed

• Remove all functionality deprecated in PyO3 0.18, including #[args] attribute for #[pymethods]. #3232
• Remove IntoPyPointer trait in favour of into_ptr inherent methods. #3385

Fixed

• Handle exceptions properly in PySet::discard. #3281
• The PyTupleIterator type returned by PyTuple::iter is now public and hence can be named by downstream crates. #3366
• Linking of PyOS_FSPath on PyPy. #3374
• Fix memory leak in PyTypeBuilder::build. #3401
• Disable removed FFI definitions _Py_GetAllocatedBlocks, _PyObject_GC_Malloc, and _PyObject_GC_Calloc on Python 3.11 and up. #3403
• Fix ResourceWarning and crashes related to GC when running with debug builds of CPython. #3404
• Some-wrapping of Option<T> default arguments will no longer re-wrap Some(T) or expressions evaluating to None. #3461
• Fix IterNextOutput::Return not returning a value on PyPy. #3471
• Emit compile errors instead of ignoring macro invocations inside #[pymethods] blocks. #3491
• Emit error on invalid arguments to #[new], #[classmethod], #[staticmethod], and #[classattr]. #3484
• Disable PyMarshal_WriteObjectToString from PyMarshal_ReadObjectFromString with the abi3 feature. #3490
• Fix FFI definitions for _PyFrameEvalFunction on Python 3.11 and up (it now receives a _PyInterpreterFrame opaque struct). #3500

Added

• Add FFI definitions PyState_AddModule, PyState_RemoveModule and PyState_FindModule for PyPy 3.9 and up. #3295
• Add FFI definitions _PyObject_CallFunction_SizeT and _PyObject_CallMethod_SizeT. #3297
• Add a "performance" section to the guide collecting performance-related tricks and problems. #3304
• Add PyErr::Display for all Python versions, and FFI symbol PyErr_DisplayException for Python 3.12. #3334
• Add FFI definition PyType_GetDict() for Python 3.12. #3339
• Add PyAny::downcast_exact. #3346
• Add PySlice::full() to construct a full slice (::). #3353

Changed

• Update PyErr for 3.12 betas to avoid deprecated ffi methods. #3306
• Update FFI definitions of object.h for Python 3.12.0b4. #3335
• Update pyo3::ffi struct definitions to be compatible with 3.12.0b4. #3342
• Optimize conversion of float to f64 (and PyFloat::value) on non-abi3 builds. #3345

Fixed

• Fix timezone conversion bug for FixedOffset datetimes that were being incorrectly converted to and from UTC. #3269
• Fix SystemError raised in PyUnicodeDecodeError_Create on PyPy 3.10. #3297
• Correct FFI definition Py_EnterRecursiveCall to return c_int (was incorrectly returning ()). #3300
• Fix case where PyErr::matches and PyErr::is_instance returned results inconsistent with PyErr::get_type. #3313
• Fix loss of panic message in PanicException when unwinding after the exception was "normalized". #3326
• Fix PyErr::from_value and PyErr::into_value losing traceback on conversion. #3328
• Fix reference counting of immortal objects on Python 3.12.0b4. #3335

Packaging

• Extend range of supported versions of hashbrown optional dependency to include version 0.14 #3258
• Extend range of supported versions of indexmap optional dependency to include version 2. #3277
• Support PyPy 3.10. #3289

Added

• Add pyo3::types::PyFrozenSetBuilder to allow building a PyFrozenSet item by item. #3156
• Add support for converting to and from Python's ipaddress.IPv4Address/ipaddress.IPv6Address and std::net::IpAddr. #3197
• Add support for num-bigint feature in combination with abi3. #3198
• Add PyErr_GetRaisedException(), PyErr_SetRaisedException() to FFI definitions for Python 3.12 and later. #3248
• Add Python::with_pool which is a safer but more limited alternative to Python::new_pool. #3263
• Add PyDict::get_item_with_error on PyPy. #3270
• Allow #[new] methods may to return Py<Self> in order to return existing instances. #3287

Fixed

• Fix conversion of classes implementing __complex__ to Complex when using abi3 or PyPy. #3185
• Stop suppressing unrelated exceptions in PyAny::hasattr. #3271
• Fix memory leak when creating PySet or PyFrozenSet or returning types converted into these internally, e.g. HashSet or BTreeSet. #3286

Packaging

• Correct dependency on syn to version 1.0.85 instead of the incorrect version 1.0.56. #3152

Added

• Accept text_signature option (and automatically generate signature) for #[new] in #[pymethods]. #2980
• Add support for converting to and from Python's decimal.Decimal and rust_decimal::Decimal. #3016
• Add #[pyo3(from_item_all)] when deriving FromPyObject to specify get_item as getter for all fields. #3120
• Add pyo3::exceptions::PyBaseExceptionGroup for Python 3.11, and corresponding FFI definition PyExc_BaseExceptionGroup. #3141
• Accept #[new] with #[classmethod] to create a constructor which receives a (subtype's) class/PyType as its first argument. #3157
• Add PyClass::get and Py::get for GIL-independent access to classes with #[pyclass(frozen)]. #3158
• Add PyAny::is_exact_instance and PyAny::is_exact_instance_of. #3161

Changed

• PyAny::is_instance_of::<T>(obj) is now equivalent to T::is_type_of(obj), and now returns bool instead of PyResult<bool>. #2881
• Deprecate text_signature option on #[pyclass] structs. #2980
• No longer wrap anyhow::Error/eyre::Report containing a basic PyErr without a chain in a PyRuntimeError. #3004
• • Change #[getter] and #[setter] to use a common call "trampoline" to slightly reduce generated code size and compile times. #3029
• Improve default values for str, numbers and bool in automatically-generated text_signature. #3050
• Improve default value for None in automatically-generated text_signature. #3066
• Rename PySequence::list and PySequence::tuple to PySequence::to_list and PySequence::to_tuple. (The old names continue to exist as deprecated forms.) #3111
• Extend the lifetime of the GIL token returned by PyRef::py and PyRefMut::py to match the underlying borrow. #3131
• Safe access to the GIL, for example via Python::with_gil, is now locked inside of implementations of the __traverse__ slot. #3168

Removed

• Remove all functionality deprecated in PyO3 0.17, most prominently Python::acquire_gil is replaced by Python::with_gil. #2981

Fixed

• Correct FFI definitions PyGetSetDef, PyMemberDef, PyStructSequence_Field and PyStructSequence_Desc to have *const c_char members for name and doc (not *mut c_char). #3036
• Fix panic on fmt::Display, instead return "<unprintable object>" string and report error via sys.unraisablehook() #3062
• Fix a compile error of "temporary value dropped while borrowed" when #[pyfunction]s take references into #[pyclass]es #3142
• Fix crashes caused by PyO3 applying deferred reference count updates when entering a __traverse__ implementation. #3168
• Forbid running the Drop implementations of unsendable classes on other threads. #3176
• Fix a compile error when #[pymethods] items come from somewhere else (for example, as a macro argument) and a custom receiver like Py<Self> is used. #3178

Added

• Add GILProtected<T> to mediate concurrent access to a value using Python's global interpreter lock (GIL). #2975
• Support PyASCIIObject / PyUnicode and associated methods on big-endian architectures. #3015
• Add FFI definition _PyDict_Contains_KnownHash() for CPython 3.10 and up. #3088

Fixed

• Fix compile error for #[pymethods] and #[pyfunction] called "output". #3022
• Fix compile error in generated code for magic methods implemented as a #[staticmethod]. #3055
• Fix is_instance for PyDateTime (would incorrectly check for a PyDate). #3071
• Fix upstream deprecation of PyUnicode_InternImmortal since Python 3.10. #3071

Packaging

• Disable default features of chrono to avoid depending on time v0.1.x. #2939

Added

• Implement IntoPy<PyObject>, ToPyObject and FromPyObject for Cow<[u8]> to efficiently handle both bytes and bytearray objects. #2899
• Implement IntoPy<PyObject>, ToPyObject and FromPyObject for Cell<T>. #3014
• Add PyList::to_tuple(), as a convenient and efficient conversion from lists to tuples. #3042
• Add PyTuple::to_list(), as a convenient and efficient conversion from tuples to lists. #3044

Changed

• Optimize PySequence conversion for list and tuple inputs. #2944
• Improve exception raised when creating #[pyclass] type object fails during module import. #2947
• Optimize PyMapping conversion for dict inputs. #2954
• Allow create_exception! to take a dotted.module to place the exception in a submodule. #2979

Fixed

• Fix a reference counting race condition affecting PyObjects cloned in allow_threads blocks. #2952
• Fix clippy::redundant_closure lint on default arguments in #[pyo3(signature = (...))] annotations. #2990
• Fix non_snake_case lint on generated code in #[pyfunction] macro. #2993
• Fix some FFI definitions for the upcoming PyPy 3.10 release. #3031

Added

• Add PyErr::write_unraisable(). #2889
• Add Python::Ellipsis() and PyAny::is_ellipsis() methods. #2911
• Add PyDict::update() and PyDict::update_if_missing() methods. #2912

Changed

• FFI definition PyIter_Check on CPython 3.7 is now implemented as hasattr(type(obj), "__next__"), which works correctly on all platforms and adds support for abi3. #2914
• Warn about unknown config keys in PYO3_CONFIG_FILE instead of denying. #2926

Fixed

• Send errors returned by __releasebuffer__ to sys.unraisablehook rather than causing SystemError. #2886
• Fix downcast to PyIterator succeeding for Python classes which did not implement __next__. #2914
• Fix segfault in __traverse__ when visiting None fields of Option<T: AsPyPointer>. #2921
• Fix #[pymethods(crate = "...")] option being ignored. #2923
• Link against pythonXY_d.dll for debug Python builds on Windows. #2937

Packaging

• Relax indexmap optional depecency to allow >= 1.6, < 2. #2849
• Relax hashbrown optional dependency to allow >= 0.9, < 0.14. #2875
• Update memoffset dependency to 0.8. #2875

Added

• Add GILOnceCell::get_or_try_init for fallible GILOnceCell initialization. #2398
• Add experimental feature experimental-inspect with type_input() and type_output() helpers to get the Python type of any Python-compatible object. #2490 #2882
• The #[pyclass] macro can now take get_all and set_all to create getters and setters for every field. #2692
• Add #[pyo3(signature = (...))] option for #[pyfunction] and #[pymethods]. #2702
• pyo3-build-config: rebuild when PYO3_ENVIRONMENT_SIGNATURE environment variable value changes. #2727
• Add conversions between non-zero int types in std::num and Python int. #2730
• Add Py::downcast() as a companion to PyAny::downcast(), as well as downcast_unchecked() for both types. #2734
• Add types for all built-in Warning classes as well as PyErr::warn_explicit. #2742
• Add abi3-py311 feature. #2776
• Add FFI definition _PyErr_ChainExceptions() for CPython. #2788
• Add FFI definitions PyVectorcall_NARGS and PY_VECTORCALL_ARGUMENTS_OFFSET for PyPy 3.8 and up. #2811
• Add PyList::get_item_unchecked for PyPy. #2827

Changed

• PyO3's macros now emit a much nicer error message if function return values don't implement the required trait(s). #2664
• Use a TypeError, rather than a ValueError, when refusing to treat a str as a Vec. #2685
• Change PyCFunction::new_closure to take name and doc arguments. #2686
• PyType::is_subclass, PyErr::is_instance and PyAny::is_instance now take &PyAny instead of &PyType arguments, so that they work with objects that pretend to be types using __subclasscheck__ and __instancecheck__. #2695
• Deprecate #[args] attribute and passing "args" specification directly to #[pyfunction] in favor of the new #[pyo3(signature = (...))] option. #2702
• Deprecate required arguments after Option<T> arguments to #[pyfunction] and #[pymethods] without also using #[pyo3(signature)] to specify whether the arguments should be required or have defaults. #2703
• Change #[pyfunction] and #[pymethods] to use a common call "trampoline" to slightly reduce generated code size and compile times. #2705
• PyAny::cast_as() and Py::cast_as() are now deprecated in favor of PyAny::downcast() and the new Py::downcast(). #2734
• Relax lifetime bounds on PyAny::downcast(). #2734
• Automatically generate __text_signature__ for all Python functions created using #[pyfunction] and #[pymethods]. #2784
• Accept any iterator in PySet::new and PyFrozenSet::new. #2795
• Mixing #[cfg(...)] and #[pyo3(...)] attributes on #[pyclass] struct fields will now work. #2796
• Re-enable PyFunction on when building for abi3 or PyPy. #2838
• Improve derive(FromPyObject) to use intern! when applicable for #[pyo3(item)]. #2879

Removed

• Remove the deprecated pyproto feature, #[pyproto] macro, and all accompanying APIs. #2587
• Remove all functionality deprecated in PyO3 0.16. #2843

Fixed

• Disable PyModule::filename on PyPy. #2715
• PyCodeObject is now once again defined with fields on Python 3.7. #2726
• Raise a TypeError if #[new] pymethods with no arguments receive arguments when called from Python. #2749
• Use the NOARGS argument calling convention for methods that have a single py: Python argument (as a performance optimization). #2760
• Fix truncation of isize values to c_long in PySlice::new. #2769
• Fix soundness issue with FFI definition PyUnicodeDecodeError_Create on PyPy leading to indeterminate behavior (typically a TypeError). #2772
• Allow functions taking **kwargs to accept keyword arguments which share a name with a positional-only argument (as permitted by PEP 570). #2800
• Fix unresolved symbol for PyObject_Vectorcall on PyPy 3.9 and up. #2811
• Fix memory leak in PyCFunction::new_closure. #2842

Packaging

• Support Python 3.11. (Previous versions of PyO3 0.17 have been tested against Python 3.11 release candidates and are expected to be compatible, this is the first version tested against Python 3.11.0.) #2708

Added

• Implemented ExactSizeIterator for PyListIterator, PyDictIterator, PySetIterator and PyFrozenSetIterator. #2676

Fixed

• Fix regression of impl FromPyObject for [T; N] no longer accepting types passing PySequence_Check, e.g. NumPy arrays, since version 0.17.0. This the same fix that was applied impl FromPyObject for Vec<T> in version 0.17.1 extended to fixed-size arrays. #2675
• Fix UB in FunctionDescription::extract_arguments_fastcall due to creating slices from a null pointer. #2687

Packaging

• Added optional chrono feature to convert chrono types into types in the datetime module. #2612

Added

• Add support for num-bigint feature on PyPy. #2626

Fixed

• Correctly implement __richcmp__ for enums, fixing __ne__ returning always returning True. #2622
• Fix compile error since 0.17.0 with Option<&SomePyClass> argument with a default. #2630
• Fix regression of impl FromPyObject for Vec<T> no longer accepting types passing PySequence_Check, e.g. NumPy arrays, since 0.17.0. #2631

Fixed

• Fix visibility of PyDictItems, PyDictKeys, and PyDictValues types added in PyO3 0.17.0.
• Fix compile failure when using #[pyo3(from_py_with = "...")] attribute on an argument of type Option<T>. #2592
• Fix clippy redundant-closure lint on **kwargs arguments for #[pyfunction] and #[pymethods]. #2595

Packaging

• Update inventory dependency to 0.3 (the multiple-pymethods feature now requires Rust 1.62 for correctness). #2492

Added

• Add timezone_utc. #1588
• Implement ToPyObject for [T; N]. #2313
• Add PyDictKeys, PyDictValues and PyDictItems Rust types. #2358
• Add append_to_inittab. #2377
• Add FFI definition PyFrame_GetCode. #2406
• Add PyCode and PyFrame high level objects. #2408
• Add FFI definitions Py_fstring_input, sendfunc, and _PyErr_StackItem. #2423
• Add PyDateTime::new_with_fold, PyTime::new_with_fold, PyTime::get_fold, and PyDateTime::get_fold for PyPy. #2428
• Add #[pyclass(frozen)]. #2448
• Accept #[pyo3(name)] on enum variants. #2457
• Add CompareOp::matches to implement __richcmp__ as the result of a Rust std::cmp::Ordering comparison. #2460
• Add PySuper type. #2486
• Support PyPy on Windows with the generate-import-lib feature. #2506
• Add FFI definitions Py_EnterRecursiveCall and Py_LeaveRecursiveCall. #2511
• Add PyDict::get_item_with_error. #2536
• Add #[pyclass(sequence)] option. #2567

Changed

• Change datetime constructors taking a tzinfo to take Option<&PyTzInfo> instead of Option<&PyObject>: PyDateTime::new, PyDateTime::new_with_fold, PyTime::new, and PyTime::new_with_fold. #1588
• Move PyTypeObject::type_object method to the PyTypeInfo trait, and deprecate the PyTypeObject trait. #2287
• Methods of Py and PyAny now accept impl IntoPy<Py<PyString>> rather than just &str to allow use of the intern! macro. #2312
• Change the deprecated pyproto feature to be opt-in instead of opt-out. #2322
• Emit better error messages when #[pyfunction] return types do not implement IntoPy. #2326
• Require T: IntoPy for impl<T, const N: usize> IntoPy<PyObject> for [T; N] instead of T: ToPyObject. #2326
• Deprecate the ToBorrowedObject trait. #2333
• Iterators over PySet and PyDict will now panic if the underlying collection is mutated during the iteration. #2380
• Iterators over PySet and PyDict will now panic if the underlying collection is mutated during the iteration. #2380
• Allow #[classattr] methods to be fallible. #2385
• Prevent multiple #[pymethods] with the same name for a single #[pyclass]. #2399
• Fixup lib_name when using PYO3_CONFIG_FILE. #2404
• Add a message to the ValueError raised by the #[derive(FromPyObject)] implementation for a tuple struct. #2414
• Allow #[classattr] methods to take Python argument. #2456
• Rework PyCapsule type to resolve soundness issues: #2485
  • PyCapsule::new and PyCapsule::new_with_destructor now take name: Option<CString> instead of &CStr.
  • The destructor F in PyCapsule::new_with_destructor must now be Send.
  • PyCapsule::get_context deprecated in favor of PyCapsule::context which doesn't take a py: Python<'_> argument.
  • PyCapsule::set_context no longer takes a py: Python<'_> argument.
  • PyCapsule::name now returns PyResult<Option<&CStr>> instead of &CStr.
• FromPyObject::extract for Vec<T> no longer accepts Python str inputs. #2500
• Ensure each #[pymodule] is only initialized once. #2523
• pyo3_build_config::add_extension_module_link_args now also emits linker arguments for wasm32-unknown-emscripten. #2538
• Type checks for PySequence and PyMapping now require inputs to inherit from (or register with) collections.abc.Sequence and collections.abc.Mapping respectively. #2477
• Disable PyFunction on when building for abi3 or PyPy. #2542
• Deprecate Python::acquire_gil. #2549

Removed

• Remove all functionality deprecated in PyO3 0.15. #2283
• Make the Dict, WeakRef and BaseNativeType members of the PyClass private implementation details. #2572

Fixed

• Enable incorrectly disabled FFI definition PyThreadState_DeleteCurrent. #2357
• Fix wrap_pymodule interactions with name resolution rules: it no longer "sees through" glob imports of use submodule::* when submodule::submodule is a #[pymodule]. #2363
• Correct FFI definition PyEval_EvalCodeEx to take *const *mut PyObject array arguments instead of *mut *mut PyObject. #2368
• Fix "raw-ident" structs (e.g. #[pyclass] struct r#RawName) incorrectly having r# at the start of the class name created in Python. #2395
• Correct FFI definition Py_tracefunc to be unsafe extern "C" fn (was previously safe). #2407
• Fix compile failure with #[pyo3(from_py_with = "...")] annotations on a field in a #[derive(FromPyObject)] struct. #2414
• Fix FFI definitions _PyDateTime_BaseTime and _PyDateTime_BaseDateTime lacking leading underscores in their names. #2421
• Remove FFI definition PyArena on Python 3.10 and up. #2421
• Fix FFI definition PyCompilerFlags missing member cf_feature_version on Python 3.8 and up. #2423
• Fix FFI definition PyAsyncMethods missing member am_send on Python 3.10 and up. #2423
• Fix FFI definition PyGenObject having multiple incorrect members on various Python versions. #2423
• Fix FFI definition PySyntaxErrorObject missing members end_lineno and end_offset on Python 3.10 and up. #2423
• Fix FFI definition PyHeapTypeObject missing member ht_module on Python 3.9 and up. #2423
• Fix FFI definition PyFrameObject having multiple incorrect members on various Python versions. #2424 #2434
• Fix FFI definition PyTypeObject missing deprecated field tp_print on Python 3.8. #2428
• Fix FFI definitions PyDateTime_CAPI. PyDateTime_Date, PyASCIIObject, PyBaseExceptionObject, PyListObject, and PyTypeObject on PyPy. #2428
• Fix FFI definition _inittab field initfunc typo'd as initfun. #2431
• Fix FFI definitions _PyDateTime_BaseTime and _PyDateTime_BaseDateTime incorrectly having fold member. #2432
• Fix FFI definitions PyTypeObject. PyHeapTypeObject, and PyCFunctionObject having incorrect members on PyPy 3.9. #2433
• Fix FFI definition PyGetSetDef to have *const c_char for doc member (not *mut c_char). #2439
• Fix #[pyo3(from_py_with = "...")] being ignored for 1-element tuple structs and transparent structs. #2440
• Use memoffset to avoid UB when computing PyCell layout. #2450
• Fix incorrect enum names being returned by the generated repr for enums renamed by #[pyclass(name = "...")] #2457
• Fix PyObject_CallNoArgs incorrectly being available when building for abi3 on Python 3.9. #2476
• Fix several clippy warnings generated by #[pyfunction] arguments. #2503

Changed

• Fix soundness issues with PyCapsule type with select workarounds. Users are encourage to upgrade to PyO3 0.17 at their earliest convenience which contains API breakages which fix the issues in a long-term fashion. #2522
  • PyCapsule::new and PyCapsule::new_with_destructor now take ownership of a copy of the name to resolve a possible use-after-free.
  • PyCapsule::name now returns an empty CStr instead of dereferencing a null pointer if the capsule has no name.
  • The destructor F in PyCapsule::new_with_destructor will never be called if the capsule is deleted from a thread other than the one which the capsule was created in (a warning will be emitted).
• Panics during drop of panic payload caught by PyO3 will now abort. #2544

Added

• Add an experimental generate-import-lib feature to support auto-generating non-abi3 python import libraries for Windows targets. #2364
• Add FFI definition Py_ExitStatusException. #2374

Changed

• Deprecate experimental generate-abi3-import-lib feature in favor of the new generate-import-lib feature. #2364

Fixed

• Added missing warn_default_encoding field to PyConfig on 3.10+. The previously missing field could result in incorrect behavior or crashes. #2370
• Fixed order of pathconfig_warnings and program_name fields of PyConfig on 3.10+. Previously, the order of the fields was swapped and this could lead to incorrect behavior or crashes. #2370

Added

• Add PyTzInfoAccess trait for safe access to time zone information. #2263
• Add an experimental generate-abi3-import-lib feature to auto-generate python3.dll import libraries for Windows. #2282
• Add FFI definitions for PyDateTime_BaseTime and PyDateTime_BaseDateTime. #2294

Changed

• Improved performance of failing calls to FromPyObject::extract which is common when functions accept multiple distinct types. #2279
• Default to "m" ABI tag when choosing libpython link name for CPython 3.7 on Unix. #2288
• Allow to compile "abi3" extensions without a working build host Python interpreter. #2293

Fixed

• Crates depending on PyO3 can collect code coverage via LLVM instrumentation using stable Rust. #2286
• Fix segfault when calling FFI methods PyDateTime_DATE_GET_TZINFO or PyDateTime_TIME_GET_TZINFO on datetime or time without a tzinfo. #2289
• Fix directory names starting with the letter n breaking serialization of the interpreter configuration on Windows since PyO3 0.16.3. #2299

Packaging

• Extend parking_lot dependency supported versions to include 0.12. #2239

Added

• Add methods to pyo3_build_config::InterpreterConfig to run Python scripts using the configured executable. #2092
• Add as_bytes method to Py<PyBytes>. #2235
• Add FFI definitions for PyType_FromModuleAndSpec, PyType_GetModule, PyType_GetModuleState and PyModule_AddType. #2250
• Add pyo3_build_config::cross_compiling_from_to as a helper to detect when PyO3 is cross-compiling. #2253
• Add #[pyclass(mapping)] option to leave sequence slots empty in container implementations. #2265
• Add PyString::intern to enable usage of the Python's built-in string interning. #2268
• Add intern! macro which can be used to amortize the cost of creating Python strings by storing them inside a GILOnceCell. #2269
• Add PYO3_CROSS_PYTHON_IMPLEMENTATION environment variable for selecting the default cross Python implementation. #2272

Changed

• Allow #[pyo3(crate = "...", text_signature = "...")] options to be used directly in #[pyclass(crate = "...", text_signature = "...")]. #2234
• Make PYO3_CROSS_LIB_DIR environment variable optional when cross compiling. #2241
• Mark METH_FASTCALL calling convention as limited API on Python 3.10. #2250
• Deprecate pyo3_build_config::cross_compiling in favor of pyo3_build_config::cross_compiling_from_to. #2253

Fixed

• Fix abi3-py310 feature: use Python 3.10 ABI when available instead of silently falling back to the 3.9 ABI. #2242
• Use shared linking mode when cross compiling against a Framework bundle for macOS. #2233
• Fix panic during compilation when PYO3_CROSS_LIB_DIR is set for some host/target combinations. #2232
• Correct dependency version for syn to require minimal patch version 1.0.56. #2240

Packaging

• Warn when modules are imported on PyPy 3.7 versions older than PyPy 7.3.8, as they are known to have binary compatibility issues. #2217
• Ensure build script of pyo3-ffi runs before that of pyo3 to fix cross compilation. #2224

Packaging

• Extend hashbrown optional dependency supported versions to include 0.12. #2197

Fixed

• Fix incorrect platform detection for Windows in pyo3-build-config. #2198
• Fix regression from 0.16 preventing cross compiling to aarch64 macOS. #2201

Packaging

• Update MSRV to Rust 1.48. #2004
• Update indoc optional dependency to 1.0. #2004
• Drop support for Python 3.6, remove abi3-py36 feature. #2006
• pyo3-build-config no longer enables the resolve-config feature by default. #2008
• Update inventory optional dependency to 0.2. #2019
• Drop paste dependency. #2081
• The bindings found in pyo3::ffi are now a re-export of a separate pyo3-ffi crate. #2126
• Support PyPy 3.9. #2143

Added

• Add PyCapsule type exposing the Capsule API. #1980
• Add pyo3_build_config::Sysconfigdata and supporting APIs. #1996
• Add Py::setattr method. #2009
• Add #[pyo3(crate = "some::path")] option to all attribute macros (except the deprecated #[pyproto]). #2022
• Enable create_exception! macro to take an optional docstring. #2027
• Enable #[pyclass] for fieldless (aka C-like) enums. #2034
• Add buffer magic methods __getbuffer__ and __releasebuffer__ to #[pymethods]. #2067
• Add support for paths in wrap_pyfunction and wrap_pymodule. #2081
• Enable wrap_pyfunction! to wrap a #[pyfunction] implemented in a different Rust module or crate. #2091
• Add PyAny::contains method (in operator for PyAny). #2115
• Add PyMapping::contains method (in operator for PyMapping). #2133
• Add garbage collection magic magic methods __traverse__ and __clear__ to #[pymethods]. #2159
• Add support for from_py_with on struct tuples and enums to override the default from-Python conversion. #2181
• Add eq, ne, lt, le, gt, ge methods to PyAny that wrap rich_compare. #2175
• Add Py::is and PyAny::is methods to check for object identity. #2183
• Add support for the __getattribute__ magic method. #2187

Changed

• PyType::is_subclass, PyErr::is_instance and PyAny::is_instance now operate run-time type object instead of a type known at compile-time. The old behavior is still available as PyType::is_subclass_of, PyErr::is_instance_of and PyAny::is_instance_of. #1985
• Rename some methods on PyErr (the old names are just marked deprecated for now): #2026
  • pytype -> get_type
  • pvalue -> value (and deprecate equivalent instance)
  • ptraceback -> traceback
  • from_instance -> from_value
  • into_instance -> into_value
• PyErr::new_type now takes an optional docstring and now returns PyResult<Py<PyType>> rather than a ffi::PyTypeObject pointer. #2027
• Deprecate PyType::is_instance; it is inconsistent with other is_instance methods in PyO3. Instead of typ.is_instance(obj), use obj.is_instance(typ). #2031
• __getitem__, __setitem__ and __delitem__ in #[pymethods] now implement both a Python mapping and sequence by default. #2065
• Improve performance and error messages for #[derive(FromPyObject)] for enums. #2068
• Reduce generated LLVM code size (to improve compile times) for:
  • internal handle_panic helper #2074 #2158
  • #[pyfunction] and #[pymethods] argument extraction #2075 #2085
  • #[pyclass] type object creation #2076 #2081 #2157
• Respect Rust privacy rules for items wrapped with wrap_pyfunction and wrap_pymodule. #2081
• Add modulo argument to __ipow__ magic method. #2083
• Fix FFI definition for _PyCFunctionFast. #2126
• PyDateTimeAPI and PyDateTime_TimeZone_UTC are now unsafe functions instead of statics. #2126
• PyDateTimeAPI does not implicitly call PyDateTime_IMPORT anymore to reflect the original Python API more closely. Before the first call to PyDateTime_IMPORT a null pointer is returned. Therefore before calling any of the following FFI functions PyDateTime_IMPORT must be called to avoid undefined behavior: #2126
  • PyDateTime_TimeZone_UTC
  • PyDate_Check
  • PyDate_CheckExact
  • PyDateTime_Check
  • PyDateTime_CheckExact
  • PyTime_Check
  • PyTime_CheckExact
  • PyDelta_Check
  • PyDelta_CheckExact
  • PyTZInfo_Check
  • PyTZInfo_CheckExact
  • PyDateTime_FromTimestamp
  • PyDate_FromTimestamp
• Deprecate the gc option for pyclass (e.g. #[pyclass(gc)]). Just implement a __traverse__ #[pymethod]. #2159
• The ml_meth field of PyMethodDef is now represented by the PyMethodDefPointer union. 2166
• Deprecate the #[pyproto] traits. #2173

Removed

• Remove all functionality deprecated in PyO3 0.14. #2007
• Remove Default impl for PyMethodDef. #2166
• Remove PartialEq impl for Py and PyAny (use the new is instead). #2183

Fixed

• Fix undefined symbol for PyObject_HasAttr on PyPy. #2025
• Fix memory leak in PyErr::into_value. #2026
• Fix clippy warning needless-option-as-deref in code generated by #[pyfunction] and #[pymethods]. #2040
• Fix undefined behavior in PySlice::indices. #2061
• Fix the wrap_pymodule! macro using the wrong name for a #[pymodule] with a #[pyo3(name = "..")] attribute. #2081
• Fix magic methods in #[pymethods] accepting implementations with the wrong number of arguments. #2083
• Fix panic in #[pyfunction] generated code when a required argument following an Option was not provided. #2093
• Fixed undefined behavior caused by incorrect ExactSizeIterator implementations. #2124
• Fix missing FFI definition PyCMethod_New on Python 3.9 and up. #2143
• Add missing FFI definitions _PyLong_NumBits and _PyLong_AsByteArray on PyPy. #2146
• Fix memory leak in implementation of AsPyPointer for Option<T>. #2160
• Fix FFI definition of _PyLong_NumBits to return size_t instead of c_int. #2161
• Fix TypeError thrown when argument parsing failed missing the originating causes. 2177

Packaging

• Backport of PyPy 3.9 support from PyO3 0.16. #2262

Added

• Add implementations for Py::as_ref and Py::into_ref for Py<PySequence>, Py<PyIterator> and Py<PyMapping>. #1682
• Add PyTraceback type to represent and format Python tracebacks. #1977

Changed

• #[classattr] constants with a known magic method name (which is lowercase) no longer trigger lint warnings expecting constants to be uppercase. #1971

Fixed

• Fix creating #[classattr] by functions with the name of a known magic method. #1971
• Fix use of catch_unwind in allow_threads which can cause fatal crashes. #1989
• Fix build failure on PyPy when abi3 features are activated. #1991
• Fix mingw platform detection. #1993
• Fix panic in __get__ implementation when accessing descriptor on type object. #1997

Packaging

• pyo3's Cargo.toml now advertises links = "python" to inform Cargo that it links against libpython. #1819
• Added optional anyhow feature to convert anyhow::Error into PyErr. #1822
• Support Python 3.10. #1889
• Added optional eyre feature to convert eyre::Report into PyErr. #1893
• Support PyPy 3.8. #1948

Added

• Add PyList::get_item_unchecked and PyTuple::get_item_unchecked to get items without bounds checks. #1733
• Support #[doc = include_str!(...)] attributes on Rust 1.54 and up. #1746
• Add PyAny::py as a convenience for PyNativeType::py. #1751
• Add implementation of std::ops::Index<usize> for PyList, PyTuple and PySequence. #1825
• Add range indexing implementations of std::ops::Index for PyList, PyTuple and PySequence. #1829
• Add PyMapping type to represent the Python mapping protocol. #1844
• Add commonly-used sequence methods to PyList and PyTuple. #1849
• Add as_sequence methods to PyList and PyTuple. #1860
• Add support for magic methods in #[pymethods], intended as a replacement for #[pyproto]. #1864
• Add abi3-py310 feature. #1889
• Add PyCFunction::new_closure to create a Python function from a Rust closure. #1901
• Add support for positional-only arguments in #[pyfunction]. #1925
• Add PyErr::take to attempt to fetch a Python exception if present. #1957

Changed

• PyList, PyTuple and PySequence's APIs now accepts only usize indices instead of isize. #1733, #1802, #1803
• PyList::get_item and PyTuple::get_item now return PyResult<&PyAny> instead of panicking. #1733
• PySequence::in_place_repeat and PySequence::in_place_concat now return PyResult<&PySequence> instead of PyResult<()>, which is needed in case of immutable sequences such as tuples. #1803
• PySequence::get_slice now returns PyResult<&PySequence> instead of PyResult<&PyAny>. #1829
• Deprecate PyTuple::split_from. #1804
• Deprecate PyTuple::slice, new method PyTuple::get_slice added with usize indices. #1828
• Deprecate FFI definitions PyParser_SimpleParseStringFlags, PyParser_SimpleParseStringFlagsFilename, PyParser_SimpleParseFileFlags when building for Python 3.9. #1830
• Mark FFI definitions removed in Python 3.10 PyParser_ASTFromString, PyParser_ASTFromStringObject, PyParser_ASTFromFile, PyParser_ASTFromFileObject, PyParser_SimpleParseStringFlags, PyParser_SimpleParseStringFlagsFilename, PyParser_SimpleParseFileFlags, PyParser_SimpleParseString, PyParser_SimpleParseFile, Py_SymtableString, and Py_SymtableStringObject. #1830
• #[pymethods] now handles magic methods similarly to #[pyproto]. In the future, #[pyproto] may be deprecated. #1864
• Deprecate FFI definitions PySys_AddWarnOption, PySys_AddWarnOptionUnicode and PySys_HasWarnOptions. #1887
• Deprecate #[call] attribute in favor of using fn __call__. #1929
• Fix missing FFI definition _PyImport_FindExtensionObject on Python 3.10. #1942
• Change PyErr::fetch to panic in debug mode if no exception is present. #1957

Fixed

• Fix building with a conda environment on Windows. #1873
• Fix panic on Python 3.6 when calling Python::with_gil with Python initialized but threading not initialized. #1874
• Fix incorrect linking to version-specific DLL instead of python3.dll when cross-compiling to Windows with abi3. #1880
• Fix FFI definition for PyTuple_ClearFreeList incorrectly being present for Python 3.9 and up. #1887
• Fix panic in generated #[derive(FromPyObject)] for enums. #1888
• Fix cross-compiling to Python 3.7 builds with the "m" abi flag. #1908
• Fix __mod__ magic method fallback to __rmod__. #1934.
• Fix missing FFI definition _PyImport_FindExtensionObject on Python 3.10. #1942

Added

• Make pyo3_build_config::InterpreterConfig and subfields public. #1848
• Add resolve-config feature to the pyo3-build-config to control whether its build script does anything. #1856

Fixed

• Fix 0.14.4 compile regression on s390x-unknown-linux-gnu target. #1850

Changed

• Mark PyString::data as unsafe and disable it and some supporting PyUnicode FFI APIs (which depend on a C bitfield) on big-endian targets. #1834