- Add `Python::Ellipsis()` and `PyAny::is_ellipsis()` methods. [#2911](https://github.com/PyO3/pyo3/pull/2911)
- Add `PyDict::update()` and `PyDict::update_if_missing()` methods. [#2912](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2914)
- Warn about unknown config keys in `PYO3_CONFIG_FILE` instead of denying. [#2926](https://github.com/PyO3/pyo3/pull/2926)
### Fixed
- Send errors returned by `__releasebuffer__` to `sys.unraisablehook` rather than causing `SystemError`. [#2886](https://github.com/PyO3/pyo3/pull/2886)
- Fix downcast to `PyIterator` succeeding for Python classes which did not implement `__next__`. [#2914](https://github.com/PyO3/pyo3/pull/2914)
- Fix segfault in `__traverse__` when visiting `None` fields of `Option<T: AsPyPointer>`. [#2921](https://github.com/PyO3/pyo3/pull/2921)
- Fix `#[pymethods(crate = "...")]` option being ignored. [#2923](https://github.com/PyO3/pyo3/pull/2923)
- Link against `pythonXY_d.dll` for debug Python builds on Windows. [#2937](https://github.com/PyO3/pyo3/pull/2937)
- Update `memoffset` dependency to 0.8. [#2875](https://github.com/PyO3/pyo3/pull/2875)
### Added
- Add `GILOnceCell::get_or_try_init` for fallible `GILOnceCell` initialization. [#2398](https://github.com/PyO3/pyo3/pull/2398)
- Add experimental feature `experimental-inspect` with `type_input()` and `type_output()` helpers to get the Python type of any Python-compatible object. [#2490](https://github.com/PyO3/pyo3/pull/2490) [#2882](https://github.com/PyO3/pyo3/pull/2882)
- The `#[pyclass]` macro can now take `get_all` and `set_all` to create getters and setters for every field. [#2692](https://github.com/PyO3/pyo3/pull/2692)
- Add `#[pyo3(signature = (...))]` option for `#[pyfunction]` and `#[pymethods]`. [#2702](https://github.com/PyO3/pyo3/pull/2702)
-`pyo3-build-config`: rebuild when `PYO3_ENVIRONMENT_SIGNATURE` environment variable value changes. [#2727](https://github.com/PyO3/pyo3/pull/2727)
- Add conversions between non-zero int types in `std::num` and Python `int`. [#2730](https://github.com/PyO3/pyo3/pull/2730)
- Add `Py::downcast()` as a companion to `PyAny::downcast()`, as well as `downcast_unchecked()` for both types. [#2734](https://github.com/PyO3/pyo3/pull/2734)
- Add types for all built-in `Warning` classes as well as `PyErr::warn_explicit`. [#2742](https://github.com/PyO3/pyo3/pull/2742)
- Add FFI definition `_PyErr_ChainExceptions()` for CPython. [#2788](https://github.com/PyO3/pyo3/pull/2788)
- Add FFI definitions `PyVectorcall_NARGS` and `PY_VECTORCALL_ARGUMENTS_OFFSET` for PyPy 3.8 and up. [#2811](https://github.com/PyO3/pyo3/pull/2811)
- Add `PyList::get_item_unchecked` for PyPy. [#2827](https://github.com/PyO3/pyo3/pull/2827)
### Changed
- PyO3's macros now emit a much nicer error message if function return values don't implement the required trait(s). [#2664](https://github.com/PyO3/pyo3/pull/2664)
- Use a TypeError, rather than a ValueError, when refusing to treat a str as a Vec. [#2685](https://github.com/PyO3/pyo3/pull/2685)
- Change `PyCFunction::new_closure` to take `name` and `doc` arguments. [#2686](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2695)
- Deprecate `#[args]` attribute and passing "args" specification directly to `#[pyfunction]` in favor of the new `#[pyo3(signature = (...))]` option. [#2702](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2703)
- Change `#[pyfunction]` and `#[pymethods]` to use a common call "trampoline" to slightly reduce generated code size and compile times. [#2705](https://github.com/PyO3/pyo3/pull/2705)
-`PyAny::cast_as()` and `Py::cast_as()` are now deprecated in favor of `PyAny::downcast()` and the new `Py::downcast()`. [#2734](https://github.com/PyO3/pyo3/pull/2734)
- Relax lifetime bounds on `PyAny::downcast()`. [#2734](https://github.com/PyO3/pyo3/pull/2734)
- Automatically generate `__text_signature__` for all Python functions created using `#[pyfunction]` and `#[pymethods]`. [#2784](https://github.com/PyO3/pyo3/pull/2784)
- Accept any iterator in `PySet::new` and `PyFrozenSet::new`. [#2795](https://github.com/PyO3/pyo3/pull/2795)
- Mixing `#[cfg(...)]` and `#[pyo3(...)]` attributes on `#[pyclass]` struct fields will now work. [#2796](https://github.com/PyO3/pyo3/pull/2796)
- Re-enable `PyFunction` on when building for abi3 or PyPy. [#2838](https://github.com/PyO3/pyo3/pull/2838)
- Remove the deprecated `pyproto` feature, `#[pyproto]` macro, and all accompanying APIs. [#2587](https://github.com/PyO3/pyo3/pull/2587)
- Remove all functionality deprecated in PyO3 0.16. [#2843](https://github.com/PyO3/pyo3/pull/2843)
### Fixed
- Disable `PyModule::filename` on PyPy. [#2715](https://github.com/PyO3/pyo3/pull/2715)
-`PyCodeObject` is now once again defined with fields on Python 3.7. [#2726](https://github.com/PyO3/pyo3/pull/2726)
- Raise a `TypeError` if `#[new]` pymethods with no arguments receive arguments when called from Python. [#2749](https://github.com/PyO3/pyo3/pull/2749)
- Use the `NOARGS` argument calling convention for methods that have a single `py: Python` argument (as a performance optimization). [#2760](https://github.com/PyO3/pyo3/pull/2760)
- Fix truncation of `isize` values to `c_long` in `PySlice::new`. [#2769](https://github.com/PyO3/pyo3/pull/2769)
- Fix soundness issue with FFI definition `PyUnicodeDecodeError_Create` on PyPy leading to indeterminate behavior (typically a `TypeError`). [#2772](https://github.com/PyO3/pyo3/pull/2772)
- Allow functions taking `**kwargs` to accept keyword arguments which share a name with a positional-only argument (as permitted by PEP 570). [#2800](https://github.com/PyO3/pyo3/pull/2800)
- Fix unresolved symbol for `PyObject_Vectorcall` on PyPy 3.9 and up. [#2811](https://github.com/PyO3/pyo3/pull/2811)
- Fix memory leak in `PyCFunction::new_closure`. [#2842](https://github.com/PyO3/pyo3/pull/2842)
- 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](https://github.com/PyO3/pyo3/pull/2708)
### Added
- Implemented `ExactSizeIterator` for `PyListIterator`, `PyDictIterator`, `PySetIterator` and `PyFrozenSetIterator`. [#2676](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2675)
- Fix UB in `FunctionDescription::extract_arguments_fastcall` due to creating slices from a null pointer. [#2687](https://github.com/PyO3/pyo3/pull/2687)
- Fix compile error since 0.17.0 with `Option<&SomePyClass>` argument with a default. [#2630](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2631)
- Fix compile failure when using `#[pyo3(from_py_with = "...")]` attribute on an argument of type `Option<T>`. [#2592](https://github.com/PyO3/pyo3/pull/2592)
- Update inventory dependency to `0.3` (the `multiple-pymethods` feature now requires Rust 1.62 for correctness). [#2492](https://github.com/PyO3/pyo3/pull/2492)
- Add `PyDateTime::new_with_fold`, `PyTime::new_with_fold`, `PyTime::get_fold`, and `PyDateTime::get_fold` for PyPy. [#2428](https://github.com/PyO3/pyo3/pull/2428)
- Accept `#[pyo3(name)]` on enum variants. [#2457](https://github.com/PyO3/pyo3/pull/2457)
- Add `CompareOp::matches` to implement `__richcmp__` as the result of a Rust `std::cmp::Ordering` comparison. [#2460](https://github.com/PyO3/pyo3/pull/2460)
- 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](https://github.com/PyO3/pyo3/pull/1588)
- Move `PyTypeObject::type_object` method to the `PyTypeInfo` trait, and deprecate the `PyTypeObject` trait. [#2287](https://github.com/PyO3/pyo3/pull/2287)
- Methods of `Py` and `PyAny` now accept `impl IntoPy<Py<PyString>>` rather than just `&str` to allow use of the `intern!` macro. [#2312](https://github.com/PyO3/pyo3/pull/2312)
- Change the deprecated `pyproto` feature to be opt-in instead of opt-out. [#2322](https://github.com/PyO3/pyo3/pull/2322)
- Emit better error messages when `#[pyfunction]` return types do not implement `IntoPy`. [#2326](https://github.com/PyO3/pyo3/pull/2326)
- Require `T: IntoPy` for `impl<T, const N: usize> IntoPy<PyObject> for [T; N]` instead of `T: ToPyObject`. [#2326](https://github.com/PyO3/pyo3/pull/2326)
- Deprecate the `ToBorrowedObject` trait. [#2333](https://github.com/PyO3/pyo3/pull/2333)
- Iterators over `PySet` and `PyDict` will now panic if the underlying collection is mutated during the iteration. [#2380](https://github.com/PyO3/pyo3/pull/2380)
- Iterators over `PySet` and `PyDict` will now panic if the underlying collection is mutated during the iteration. [#2380](https://github.com/PyO3/pyo3/pull/2380)
- Add a message to the `ValueError` raised by the `#[derive(FromPyObject)]` implementation for a tuple struct. [#2414](https://github.com/PyO3/pyo3/pull/2414)
- Allow `#[classattr]` methods to take `Python` argument. [#2456](https://github.com/PyO3/pyo3/pull/2456)
- Rework `PyCapsule` type to resolve soundness issues: [#2485](https://github.com/PyO3/pyo3/pull/2485)
-`FromPyObject::extract` for `Vec<T>` no longer accepts Python `str` inputs. [#2500](https://github.com/PyO3/pyo3/pull/2500)
- Ensure each `#[pymodule]` is only initialized once. [#2523](https://github.com/PyO3/pyo3/pull/2523)
-`pyo3_build_config::add_extension_module_link_args` now also emits linker arguments for `wasm32-unknown-emscripten`. [#2538](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2477)
- Disable `PyFunction` on when building for abi3 or PyPy. [#2542](https://github.com/PyO3/pyo3/pull/2542)
- Make the `Dict`, `WeakRef` and `BaseNativeType` members of the `PyClass` private implementation details. [#2572](https://github.com/PyO3/pyo3/pull/2572)
- 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](https://github.com/PyO3/pyo3/pull/2363)
- Correct FFI definition `PyEval_EvalCodeEx` to take `*const *mut PyObject` array arguments instead of `*mut *mut PyObject`. [#2368](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2395)
- Fix compile failure with `#[pyo3(from_py_with = "...")]` annotations on a field in a `#[derive(FromPyObject)]` struct. [#2414](https://github.com/PyO3/pyo3/pull/2414)
- Fix FFI definitions `_PyDateTime_BaseTime` and `_PyDateTime_BaseDateTime` lacking leading underscores in their names. [#2421](https://github.com/PyO3/pyo3/pull/2421)
- Fix FFI definition `PyCompilerFlags` missing member `cf_feature_version` on Python 3.8 and up. [#2423](https://github.com/PyO3/pyo3/pull/2423)
- Fix FFI definition `PyAsyncMethods` missing member `am_send` on Python 3.10 and up. [#2423](https://github.com/PyO3/pyo3/pull/2423)
- Fix FFI definition `PyGenObject` having multiple incorrect members on various Python versions. [#2423](https://github.com/PyO3/pyo3/pull/2423)
- Fix FFI definition `PySyntaxErrorObject` missing members `end_lineno` and `end_offset` on Python 3.10 and up. [#2423](https://github.com/PyO3/pyo3/pull/2423)
- Fix FFI definition `PyHeapTypeObject` missing member `ht_module` on Python 3.9 and up. [#2423](https://github.com/PyO3/pyo3/pull/2423)
- Fix FFI definition `PyFrameObject` having multiple incorrect members on various Python versions. [#2424](https://github.com/PyO3/pyo3/pull/2424) [#2434](https://github.com/PyO3/pyo3/pull/2434)
- Fix FFI definitions `PyTypeObject`. `PyHeapTypeObject`, and `PyCFunctionObject` having incorrect members on PyPy 3.9. [#2433](https://github.com/PyO3/pyo3/pull/2433)
- Fix `#[pyo3(from_py_with = "...")]` being ignored for 1-element tuple structs and transparent structs. [#2440](https://github.com/PyO3/pyo3/pull/2440)
- Use `memoffset` to avoid UB when computing `PyCell` layout. [#2450](https://github.com/PyO3/pyo3/pull/2450)
- Fix incorrect enum names being returned by the generated `repr` for enums renamed by `#[pyclass(name = "...")]` [#2457](https://github.com/PyO3/pyo3/pull/2457)
- Fix `PyObject_CallNoArgs` incorrectly being available when building for abi3 on Python 3.9. [#2476](https://github.com/PyO3/pyo3/pull/2476)
- 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](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2544)
- Add an experimental `generate-import-lib` feature to support auto-generating non-abi3 python import libraries for Windows targets. [#2364](https://github.com/PyO3/pyo3/pull/2364)
- Deprecate experimental `generate-abi3-import-lib` feature in favor of the new `generate-import-lib` feature. [#2364](https://github.com/PyO3/pyo3/pull/2364)
- Added missing `warn_default_encoding` field to `PyConfig` on 3.10+. The previously missing field could result in incorrect behavior or crashes. [#2370](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2370)
- Add an experimental `generate-abi3-import-lib` feature to auto-generate `python3.dll` import libraries for Windows. [#2282](https://github.com/PyO3/pyo3/pull/2282)
- Improved performance of failing calls to `FromPyObject::extract` which is common when functions accept multiple distinct types. [#2279](https://github.com/PyO3/pyo3/pull/2279)
- Fix segfault when calling FFI methods `PyDateTime_DATE_GET_TZINFO` or `PyDateTime_TIME_GET_TZINFO` on `datetime` or `time` without a tzinfo. [#2289](https://github.com/PyO3/pyo3/pull/2289)
- Fix directory names starting with the letter `n` breaking serialization of the interpreter configuration on Windows since PyO3 0.16.3. [#2299](https://github.com/PyO3/pyo3/pull/2299)
- Add methods to `pyo3_build_config::InterpreterConfig` to run Python scripts using the configured executable. [#2092](https://github.com/PyO3/pyo3/pull/2092)
- Add `as_bytes` method to `Py<PyBytes>`. [#2235](https://github.com/PyO3/pyo3/pull/2235)
- Add FFI definitions for `PyType_FromModuleAndSpec`, `PyType_GetModule`, `PyType_GetModuleState` and `PyModule_AddType`. [#2250](https://github.com/PyO3/pyo3/pull/2250)
- Add `pyo3_build_config::cross_compiling_from_to` as a helper to detect when PyO3 is cross-compiling. [#2253](https://github.com/PyO3/pyo3/pull/2253)
- Add `#[pyclass(mapping)]` option to leave sequence slots empty in container implementations. [#2265](https://github.com/PyO3/pyo3/pull/2265)
- Add `intern!` macro which can be used to amortize the cost of creating Python strings by storing them inside a `GILOnceCell`. [#2269](https://github.com/PyO3/pyo3/pull/2269)
- Deprecate `pyo3_build_config::cross_compiling` in favor of `pyo3_build_config::cross_compiling_from_to`. [#2253](https://github.com/PyO3/pyo3/pull/2253)
- Fix `abi3-py310` feature: use Python 3.10 ABI when available instead of silently falling back to the 3.9 ABI. [#2242](https://github.com/PyO3/pyo3/pull/2242)
- Use shared linking mode when cross compiling against a [Framework bundle](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/FrameworkAnatomy.html) for macOS. [#2233](https://github.com/PyO3/pyo3/pull/2233)
- Fix panic during compilation when `PYO3_CROSS_LIB_DIR` is set for some host/target combinations. [#2232](https://github.com/PyO3/pyo3/pull/2232)
- Correct dependency version for `syn` to require minimal patch version 1.0.56. [#2240](https://github.com/PyO3/pyo3/pull/2240)
- 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](https://github.com/PyO3/pyo3/pull/2217)
- Add `PyCapsule` type exposing the [Capsule API](https://docs.python.org/3/c-api/capsule.html#capsules). [#1980](https://github.com/PyO3/pyo3/pull/1980)
- Add `pyo3_build_config::Sysconfigdata` and supporting APIs. [#1996](https://github.com/PyO3/pyo3/pull/1996)
- Add `#[pyo3(crate = "some::path")]` option to all attribute macros (except the deprecated `#[pyproto]`). [#2022](https://github.com/PyO3/pyo3/pull/2022)
- Enable `create_exception!` macro to take an optional docstring. [#2027](https://github.com/PyO3/pyo3/pull/2027)
- Add support for `from_py_with` on struct tuples and enums to override the default from-Python conversion. [#2181](https://github.com/PyO3/pyo3/pull/2181)
-`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](https://github.com/PyO3/pyo3/pull/1985)
-`PyErr::new_type` now takes an optional docstring and now returns `PyResult<Py<PyType>>` rather than a `ffi::PyTypeObject` pointer. [#2027](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/2031)
-`__getitem__`, `__setitem__` and `__delitem__` in `#[pymethods]` now implement both a Python mapping and sequence by default. [#2065](https://github.com/PyO3/pyo3/pull/2065)
-`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](https://github.com/PyO3/pyo3/pull/2126)
- Deprecate the `gc` option for `pyclass` (e.g. `#[pyclass(gc)]`). Just implement a `__traverse__``#[pymethod]`. [#2159](https://github.com/PyO3/pyo3/pull/2159)
- Fix clippy warning `needless-option-as-deref` in code generated by `#[pyfunction]` and `#[pymethods]`. [#2040](https://github.com/PyO3/pyo3/pull/2040)
- Fix the `wrap_pymodule!` macro using the wrong name for a `#[pymodule]` with a `#[pyo3(name = "..")]` attribute. [#2081](https://github.com/PyO3/pyo3/pull/2081)
- Fix magic methods in `#[pymethods]` accepting implementations with the wrong number of arguments. [#2083](https://github.com/PyO3/pyo3/pull/2083)
- Fix panic in `#[pyfunction]` generated code when a required argument following an `Option` was not provided. [#2093](https://github.com/PyO3/pyo3/pull/2093)
- Add implementations for `Py::as_ref` and `Py::into_ref` for `Py<PySequence>`, `Py<PyIterator>` and `Py<PyMapping>`. [#1682](https://github.com/PyO3/pyo3/pull/1682)
-`#[classattr]` constants with a known magic method name (which is lowercase) no longer trigger lint warnings expecting constants to be uppercase. [#1969](https://github.com/PyO3/pyo3/pull/1969)
### Fixed
- Fix creating `#[classattr]` by functions with the name of a known magic method. [#1969](https://github.com/PyO3/pyo3/pull/1969)
-`pyo3`'s `Cargo.toml` now advertises `links = "python"` to inform Cargo that it links against *libpython*. [#1819](https://github.com/PyO3/pyo3/pull/1819)
- Added optional `anyhow` feature to convert `anyhow::Error` into `PyErr`. [#1822](https://github.com/PyO3/pyo3/pull/1822)
- Add `PyList::get_item_unchecked` and `PyTuple::get_item_unchecked` to get items without bounds checks. [#1733](https://github.com/PyO3/pyo3/pull/1733)
-`PyList::get_item` and `PyTuple::get_item` now return `PyResult<&PyAny>` instead of panicking. [#1733](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/1803)
-`PySequence::get_slice` now returns `PyResult<&PySequence>` instead of `PyResult<&PyAny>`. [#1829](https://github.com/PyO3/pyo3/pull/1829)
- Deprecate FFI definitions `PyParser_SimpleParseStringFlags`, `PyParser_SimpleParseStringFlagsFilename`, `PyParser_SimpleParseFileFlags` when building for Python 3.9. [#1830](https://github.com/PyO3/pyo3/pull/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](https://github.com/PyO3/pyo3/pull/1830)
-`#[pymethods]` now handles magic methods similarly to `#[pyproto]`. In the future, `#[pyproto]` may be deprecated. [#1864](https://github.com/PyO3/pyo3/pull/1864)
- Deprecate FFI definitions `PySys_AddWarnOption`, `PySys_AddWarnOptionUnicode` and `PySys_HasWarnOptions`. [#1887](https://github.com/PyO3/pyo3/pull/1887)
- Fix panic on Python 3.6 when calling `Python::with_gil` with Python initialized but threading not initialized. [#1874](https://github.com/PyO3/pyo3/pull/1874)
- Fix incorrect linking to version-specific DLL instead of `python3.dll` when cross-compiling to Windows with `abi3`. [#1880](https://github.com/PyO3/pyo3/pull/1880)
- Make `pyo3_build_config::InterpreterConfig` and subfields public. [#1848](https://github.com/PyO3/pyo3/pull/1848)
- Add `resolve-config` feature to the `pyo3-build-config` to control whether its build script does anything. [#1856](https://github.com/PyO3/pyo3/pull/1856)
- 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](https://github.com/PyO3/pyo3/pull/1834)
- Reduce lower bound `num-complex` optional dependency to support interop with `rust-numpy` and `ndarray` when building with the MSRV of 1.41 [#1799](https://github.com/PyO3/pyo3/pull/1799)
- Fix memory leak in `Python::run_code`. [#1806](https://github.com/PyO3/pyo3/pull/1806)
- Fix memory leak in `PyModule::from_code`. [#1810](https://github.com/PyO3/pyo3/pull/1810)
- Add `indexmap` feature to add `ToPyObject`, `IntoPy` and `FromPyObject` implementations for `indexmap::IndexMap`. [#1728](https://github.com/PyO3/pyo3/pull/1728)
- Add `pyo3_build_config::add_extension_module_link_args` to use in build scripts to set linker arguments (for macOS). [#1755](https://github.com/PyO3/pyo3/pull/1755)
- Add `Python::with_gil_unchecked` unsafe variation of `Python::with_gil` to allow obtaining a `Python` in scenarios where `Python::with_gil` would fail. [#1769](https://github.com/PyO3/pyo3/pull/1769)
- Reverted PyO3 0.14.0's use of `cargo:rustc-cdylib-link-arg` in its build script, as Cargo unintentionally allowed crates to pass linker args to downstream crates in this way. Projects supporting macOS may need to restore `.cargo/config.toml` files. [#1755](https://github.com/PyO3/pyo3/pull/1755)
- Fix regression in 0.14.0 rejecting usage of `#[doc(hidden)]` on structs and functions annotated with PyO3 macros. [#1722](https://github.com/PyO3/pyo3/pull/1722)
- Fix incorrect FFI definition of `Py_DecodeLocale`. The 2nd argument is now `*mut Py_ssize_t` instead of `Py_ssize_t`. [#1766](https://github.com/PyO3/pyo3/pull/1766)
- Extend conversions for `[T; N]` to all `N` using const generics (on Rust 1.51 and up). [#1128](https://github.com/PyO3/pyo3/pull/1128)
- Add conversions between `OsStr`/ `OsString` and Python strings. [#1379](https://github.com/PyO3/pyo3/pull/1379)
- Add conversions between `Path`/ `PathBuf` and Python strings (and `pathlib.Path` objects). [#1379](https://github.com/PyO3/pyo3/pull/1379) [#1654](https://github.com/PyO3/pyo3/pull/1654)
- Add a new set of `#[pyo3(...)]` attributes to control various PyO3 macro functionality:
-`#[pyo3(from_py_with = "...")]` function arguments and struct fields to override the default from-Python conversion. [#1411](https://github.com/PyO3/pyo3/pull/1411)
-`#[pyo3(name = "...")]` for setting Python names. [#1567](https://github.com/PyO3/pyo3/pull/1567)
-`#[pyo3(text_signature = "...")]` for setting text signature. [#1658](https://github.com/PyO3/pyo3/pull/1658)
- Allow only one `#[pymethods]` block per `#[pyclass]` by default, to remove the dependency on `inventory`. Add a `multiple-pymethods` feature to opt-in the original behavior and dependency on `inventory`. [#1457](https://github.com/PyO3/pyo3/pull/1457)
- Change `PyTimeAccess::get_fold` to return a `bool` instead of a `u8`. [#1397](https://github.com/PyO3/pyo3/pull/1397)
- Deprecate FFI definition `PyCFunction_Call` for Python 3.9 and up. [#1425](https://github.com/PyO3/pyo3/pull/1425)
- Change `PyCFunction::new` and `PyCFunction::new_with_keywords` to take `&'static str` arguments rather than implicitly copying (and leaking) them. [#1450](https://github.com/PyO3/pyo3/pull/1450)
- Add length information to `PyBufferError`s raised from `PyBuffer::copy_to_slice` and `PyBuffer::copy_from_slice`. [#1534](https://github.com/PyO3/pyo3/pull/1534)
- Automatically set `-undefined` and `dynamic_lookup` linker arguments on macOS with the `extension-module` feature. [#1539](https://github.com/PyO3/pyo3/pull/1539)
- Remove `PYO3_CROSS_INCLUDE_DIR` environment variable and the associated C header parsing functionality. [#1521](https://github.com/PyO3/pyo3/pull/1521)
-`PYO3_CROSS_LIB_DIR` environment variable no long required when compiling for x86-64 Python from macOS arm64 and reverse. [#1428](https://github.com/PyO3/pyo3/pull/1428)
- Fix incorrect `TypeError` raised when keyword-only argument passed along with a positional argument in `*args`. [#1440](https://github.com/PyO3/pyo3/pull/1440)
- Fix use of Python argument for `#[pymethods]` inside macro expansions. [#1505](https://github.com/PyO3/pyo3/pull/1505)
- No longer include `__doc__` in `__all__` generated for `#[pymodule]`. [#1509](https://github.com/PyO3/pyo3/pull/1509)
- Always use cross-compiling configuration if any of the `PYO3_CROSS` family of environment variables are set. [#1514](https://github.com/PyO3/pyo3/pull/1514)
- Fix unnecessary rebuilds when cycling between `cargo check` and `cargo clippy` in a Python virtualenv. [#1557](https://github.com/PyO3/pyo3/pull/1557)
- Fix FFI definitions of `PyEval_SetProfile`/`PyEval_SetTrace` to take `Option<Py_tracefunc>` parameters. [#1692](https://github.com/PyO3/pyo3/pull/1692)
- Fix `ToPyObject` impl for `HashSet` to accept non-default hashers. [#1702](https://github.com/PyO3/pyo3/pull/1702)
- Add unsafe API `with_embedded_python_interpreter` to initialize a Python interpreter, execute a closure, and finalize the interpreter. [#1355](https://github.com/PyO3/pyo3/pull/1355)
-`prepare_freethreaded_python` will no longer register an `atexit` handler to call `Py_Finalize`. This resolves a number of issues with incompatible C extensions causing crashes at finalization. [#1355](https://github.com/PyO3/pyo3/pull/1355)
- Mark `PyLayout::py_init`, `PyClassDict::clear_dict`, and `opt_to_pyobj` safe, as they do not perform any unsafe operations. [#1404](https://github.com/PyO3/pyo3/pull/1404)
- Fix typo in FFI definition for `PyFunction_GetCode` (was incorrectly `PyFunction_Code`). [#1387](https://github.com/PyO3/pyo3/pull/1387)
- Fix FFI definitions `PyMarshal_WriteObjectToString` and `PyMarshal_ReadObjectFromString` as available in limited API. [#1387](https://github.com/PyO3/pyo3/pull/1387)
- Fix FFI definitions `PyListObject` and those from `funcobject.h` as requiring non-limited API. [#1387](https://github.com/PyO3/pyo3/pull/1387)
- Add support for `#[pyclass(dict)]` and `#[pyclass(weakref)]` with the `abi3` feature on Python 3.9 and up. [#1342](https://github.com/PyO3/pyo3/pull/1342)
- Add an `auto-initialize` feature to control whether PyO3 should automatically initialize an embedded Python interpreter. For compatibility this feature is enabled by default in PyO3 0.13.1, but is planned to become opt-in from PyO3 0.14.0. [#1347](https://github.com/PyO3/pyo3/pull/1347)
- Deprecate FFI definitions `PyEval_CallObjectWithKeywords`, `PyEval_CallObject`, `PyEval_CallFunction`, `PyEval_CallMethod` when building for Python 3.9. [#1338](https://github.com/PyO3/pyo3/pull/1338)
- Deprecate FFI definitions `PyGetSetDef_DICT` and `PyGetSetDef_INIT` which have never been in the Python API. [#1341](https://github.com/PyO3/pyo3/pull/1341)
- Deprecate FFI definitions `PyCoro_Check`, `PyAsyncGen_Check`, and `PyCoroWrapper_Check`, which have never been in the Python API (for the first two, it is possible to use `PyCoro_CheckExact` and `PyAsyncGen_CheckExact` instead; these are the actual functions provided by the Python API). [#1348](https://github.com/PyO3/pyo3/pull/1348)
- Deprecate FFI definitions for `PyUnicode_FromUnicode`, `PyUnicode_AsUnicode` and `PyUnicode_AsUnicodeAndSize`, which will be removed from 3.12 and up due to [PEP 623](https://www.python.org/dev/peps/pep-0623/). [#1370](https://github.com/PyO3/pyo3/pull/1370)
- Remove FFI definitions `PyGen_NeedsFinalizing` and `PyImport_Cleanup` (for 3.9 and up), and `PyOS_InitInterrupts` (3.10). [#1348](https://github.com/PyO3/pyo3/pull/1348)
- Stop including `Py_TRACE_REFS` config setting automatically if `Py_DEBUG` is set on Python 3.8 and up. [#1334](https://github.com/PyO3/pyo3/pull/1334)
- Rename internal crates `pyo3cls` and `pyo3-derive-backend` to `pyo3-macros` and `pyo3-macros-backend` respectively. [#1317](https://github.com/PyO3/pyo3/pull/1317)
- Add support for building for CPython limited API. Opting-in to the limited API enables a single extension wheel built with PyO3 to be installable on multiple Python versions. This required a few minor changes to runtime behavior of of PyO3 `#[pyclass]` types. See the migration guide for full details. [#1152](https://github.com/PyO3/pyo3/pull/1152)
- Add feature flags `abi3-py36`, `abi3-py37`, `abi3-py38` etc. to set the minimum Python version when using the limited API. [#1263](https://github.com/PyO3/pyo3/pull/1263)
-`#[pyclass(subclass)]` is now required for subclassing from Rust (was previously just required for subclassing from Python). [#1152](https://github.com/PyO3/pyo3/pull/1152)
- Change `PyIterator` to be consistent with other native types: it is now used as `&PyIterator` instead of `PyIterator<'a>`. [#1176](https://github.com/PyO3/pyo3/pull/1176)
- Rename `PyTypeInfo::is_instance` and `PyTypeInfo::is_exact_instance` to `PyTypeInfo::is_type_of` and `PyTypeInfo::is_exact_type_of`. [#1278](https://github.com/PyO3/pyo3/pull/1278)
- Optimize `PyAny::call0`, `Py::call0` and `PyAny::call_method0` and `Py::call_method0` on Python 3.9 and up. [#1287](https://github.com/PyO3/pyo3/pull/1285)
- Remove deprecated ffi definitions `PyUnicode_AsUnicodeCopy`, `PyUnicode_GetMax`, `_Py_CheckRecursionLimit`, `PyObject_AsCharBuffer`, `PyObject_AsReadBuffer`, `PyObject_CheckReadBuffer` and `PyObject_AsWriteBuffer`, which will be removed in Python 3.10. [#1217](https://github.com/PyO3/pyo3/pull/1217)
- Fix missing field in `PyCodeObject` struct (`co_posonlyargcount`) - caused invalid access to other fields in Python >3.7. [#1260](https://github.com/PyO3/pyo3/pull/1260)
- Fix reference count bug in implementation of `From<Py<T>>` for `PyObject`, a regression introduced in PyO3 0.12. [#1297](https://github.com/PyO3/pyo3/pull/1297)
- Fix support for Rust versions 1.39 to 1.44, broken by an incorrect internal update to paste 1.0 which was done in PyO3 0.12.2. [#1234](https://github.com/PyO3/pyo3/pull/1234)
- Add `PyBytes::new_with` and `PyByteArray::new_with` for initialising `bytes` and `bytearray` objects using a closure. [#1074](https://github.com/PyO3/pyo3/pull/1074)
- Add `Py::as_ref` and `Py::into_ref` for converting `Py<T>` to `&T`. [#1098](https://github.com/PyO3/pyo3/pull/1098)
- Add ability to return `Result` types other than `PyResult` from `#[pyfunction]`, `#[pymethod]` and `#[pyproto]` functions. [#1106](https://github.com/PyO3/pyo3/pull/1118).
- Implement `ToPyObject`, `IntoPy`, and `FromPyObject` for [hashbrown](https://crates.io/crates/hashbrown)'s `HashMap` and `HashSet` types (requires the `hashbrown` feature). [#1114](https://github.com/PyO3/pyo3/pull/1114)
- Add `#[pyfunction(pass_module)]` and `#[pyfn(pass_module)]` to pass the module object as the first function argument. [#1143](https://github.com/PyO3/pyo3/pull/1143)
- Add `PyModule::add_function` and `PyModule::add_submodule` as typed alternatives to `PyModule::add_wrapped`. [#1143](https://github.com/PyO3/pyo3/pull/1143)
- Add native `PyCFunction` and `PyFunction` types. [#1163](https://github.com/PyO3/pyo3/pull/1163)
- Require `T: Send` for the return value `T` of `Python::allow_threads`. [#1036](https://github.com/PyO3/pyo3/pull/1036)
- Rename `PYTHON_SYS_EXECUTABLE` to `PYO3_PYTHON`. The old name will continue to work (undocumented) but will be removed in a future release. [#1039](https://github.com/PyO3/pyo3/pull/1039)
- Remove `unsafe` from signature of `PyType::as_type_ptr`. [#1047](https://github.com/PyO3/pyo3/pull/1047)
- Change return type of `PyIterator::from_object` to `PyResult<PyIterator>` (was `Result<PyIterator, PyDowncastError>`). [#1051](https://github.com/PyO3/pyo3/pull/1051)
- Change `PyObject` to be a type alias for `Py<PyAny>`. [#1063](https://github.com/PyO3/pyo3/pull/1063)
- Rework `PyErr` to be compatible with the `std::error::Error` trait: [#1067](https://github.com/PyO3/pyo3/pull/1067) [#1115](https://github.com/PyO3/pyo3/pull/1115)
- Add `PyErr::instance` for accessing `PyErr` as `&PyBaseException`.
-`PyErr`'s fields are now an implementation detail. The equivalent values can be accessed with `PyErr::ptype`, `PyErr::pvalue` and `PyErr::ptraceback`.
- Change receiver of `PyErr::print` and `PyErr::print_and_set_sys_last_vars` to `&self` (was `self`).
- Remove `PyErrValue`, `PyErr::from_value`, `PyErr::into_normalized`, and `PyErr::normalize`.
- Remove `Into<PyResult<T>>` for `PyErr` and `PyException`.
- Change methods generated by `#[pyproto]` to return `NotImplemented` if Python should try a reversed operation. #[1072](https://github.com/PyO3/pyo3/pull/1072)
- Change argument to `PyModule::add` to `impl IntoPy<PyObject>` (was `impl ToPyObject`). #[1124](https://github.com/PyO3/pyo3/pull/1124)
- Remove many exception and `PyErr` APIs; see the "changed" section above. [#1024](https://github.com/PyO3/pyo3/pull/1024) [#1067](https://github.com/PyO3/pyo3/pull/1067) [#1115](https://github.com/PyO3/pyo3/pull/1115)
- Remove `PyString::to_string` (use new `PyString::to_str`). [#1023](https://github.com/PyO3/pyo3/pull/1023)
- Correct FFI definitions `Py_SetProgramName` and `Py_SetPythonHome` to take `*const` arguments (was `*mut`). [#1021](https://github.com/PyO3/pyo3/pull/1021)
- Fix `FromPyObject` for `num_bigint::BigInt` for Python objects with an `__index__` method. [#1027](https://github.com/PyO3/pyo3/pull/1027)
- Correct FFI definition `_PyLong_AsByteArray` to take `*mut c_uchar` argument (was `*const c_uchar`). [#1029](https://github.com/PyO3/pyo3/pull/1029)
- Fix segfault with `#[pyclass(dict, unsendable)]`. [#1058](https://github.com/PyO3/pyo3/pull/1058) [#1059](https://github.com/PyO3/pyo3/pull/1059)
- Fix using `&Self` as an argument type for functions in a `#[pymethods]` block. [#1071](https://github.com/PyO3/pyo3/pull/1071)
- Fix best-effort build against PyPy 3.6. [#1092](https://github.com/PyO3/pyo3/pull/1092)
- Fix many cases of lifetime elision in `#[pyproto]` implementations. [#1093](https://github.com/PyO3/pyo3/pull/1093)
- Fix detection of Python build configuration when cross-compiling. [#1095](https://github.com/PyO3/pyo3/pull/1095)
- Always link against libpython on android with the `extension-module` feature. [#1095](https://github.com/PyO3/pyo3/pull/1095)
- Fix the `+` operator not trying `__radd__` when both `__add__` and `__radd__` are defined in `PyNumberProtocol` (and similar for all other reversible operators). [#1107](https://github.com/PyO3/pyo3/pull/1107)
-`#[pyproto]` methods can now have return value `T` or `PyResult<T>` (previously only `PyResult<T>` was supported). [#996](https://github.com/PyO3/pyo3/pull/996)
- Panics will now be raised as a Python `PanicException`. [#797](https://github.com/PyO3/pyo3/pull/797)
- Change `PyObject` and `Py<T>` reference counts to decrement immediately upon drop when the GIL is held. [#851](https://github.com/PyO3/pyo3/pull/851)
- Allow `PyIterProtocol` methods to use either `PyRef` or `PyRefMut` as the receiver type. [#856](https://github.com/PyO3/pyo3/pull/856)
- Change the implementation of `FromPyObject` for `Py<T>` to apply to a wider range of `T`, including all `T: PyClass`. [#880](https://github.com/PyO3/pyo3/pull/880)
- Move all methods from the `ObjectProtocol` trait to the `PyAny` struct. [#911](https://github.com/PyO3/pyo3/pull/911)
- Remove need for `#![feature(specialization)]` in crates depending on PyO3. [#917](https://github.com/PyO3/pyo3/pull/917)
- Fix support for `__radd__` and other `__r*__` methods as implementations for Python mathematical operators. [#839](https://github.com/PyO3/pyo3/pull/839)
- Fix panics during garbage collection when traversing objects that were already mutably borrowed. [#855](https://github.com/PyO3/pyo3/pull/855)
- Prevent `&'static` references to Python objects as arguments to `#[pyfunction]` and `#[pymethods]`. [#869](https://github.com/PyO3/pyo3/pull/869)
- Fix lifetime safety bug with `AsPyRef::as_ref`. [#876](https://github.com/PyO3/pyo3/pull/876)
- Fix `#[pyo3(get)]` attribute on `Py<T>` fields. [#880](https://github.com/PyO3/pyo3/pull/880)
- Fix segmentation faults caused by functions such as `PyList::get_item` returning borrowed objects when it was not safe to do so. [#890](https://github.com/PyO3/pyo3/pull/890)
- Implemented `IntoIterator` for `PySet` and `PyFrozenSet`. [#716](https://github.com/PyO3/pyo3/pull/716)
-`FromPyObject` is now automatically implemented for `T: Clone` pyclasses. [#730](https://github.com/PyO3/pyo3/pull/730)
-`#[pyo3(get)]` and `#[pyo3(set)]` will now use the Rust doc-comment from the field for the Python property. [#755](https://github.com/PyO3/pyo3/pull/755)
-`#[setter]` functions may now take an argument of `Pyo3::Python`. [#760](https://github.com/PyO3/pyo3/pull/760)
-`PyTypeInfo::BaseLayout` and `PyClass::BaseNativeType`. [#770](https://github.com/PyO3/pyo3/pull/770)
- The blanket implementations for `FromPyObject` for `&T` and `&mut T` are no longer specializable. Implement `PyTryFrom` for your type to control the behavior of `FromPyObject::extract` for your types. [#713](https://github.com/PyO3/pyo3/pull/713)
- The implementation for `IntoPy<U> for T` where `U: FromPy<T>` is no longer specializable. Control the behavior of this via the implementation of `FromPy`. [#713](https://github.com/PyO3/pyo3/pull/713)
- Use `parking_lot::Mutex` instead of `spin::Mutex`. [#734](https://github.com/PyO3/pyo3/pull/734)
- Bumped minimum Rust version to `1.42.0-nightly 2020-01-21`. [#761](https://github.com/PyO3/pyo3/pull/761)
-`PyRef` and `PyRefMut` are renewed for `PyCell`. [#770](https://github.com/PyO3/pyo3/pull/770)
- Some new FFI functions for Python 3.8. [#784](https://github.com/PyO3/pyo3/pull/784)
-`PyAny` is now on the top level module and prelude. [#816](https://github.com/PyO3/pyo3/pull/816)
-`"*"` in a `#[pyfunction()]` argument list incorrectly accepting any number of positional arguments (use `args = "*"` when this behavior is desired). #[792](https://github.com/PyO3/pyo3/pull/792)
- Implementing the Using the `gc` parameter for `pyclass` (e.g. `#[pyclass(gc)]`) without implementing the `class::PyGCProtocol` trait is now a compile-time error. Failing to implement this trait could lead to segfaults. [#532](https://github.com/PyO3/pyo3/pull/532)
-`PyByteArray::data` has been replaced with `PyDataArray::to_vec` because returning a `&[u8]` is unsound. (See [this comment](https://github.com/PyO3/pyo3/issues/373#issuecomment-512332696) for a great write-up for why that was unsound)
- Replace `mashup` with `paste`.
-`GILPool` gained a `Python` marker to prevent it from being misused to release Python objects without the GIL held.
- Currently, [#341](https://github.com/PyO3/pyo3/issues/341) causes `cargo test` to fail with weird linking errors when the `extension-module` feature is activated. For now you can work around this by making the `extension-module` feature optional and running the tests with `cargo test --no-default-features`:
- Added a `wrap_pymodule!` macro similar to the existing `wrap_pyfunction!` macro. Only available on python 3
- Added support for cross compiling (e.g. to arm v7) by mtp401 in [#327](https://github.com/PyO3/pyo3/pull/327). See the "Cross Compiling" section in the "Building and Distribution" chapter of the guide for more details.
- The `PyRef` and `PyRefMut` types, which allow to differentiate between an instance of a rust struct on the rust heap and an instance that is embedded inside a python object. By kngwyu in [#335](https://github.com/PyO3/pyo3/pull/335)
- Added `FromPy<T>` and `IntoPy<T>` which are equivalent to `From<T>` and `Into<T>` except that they require a gil token.
- Added `ManagedPyRef`, which should eventually replace `ToBorrowedObject`.
- A soudness hole where every instances of a `#[pyclass]` struct was considered to be part of a python object, even though you can create instances that are not part of the python heap. This was fixed through `PyRef` and `PyRefMut`.
- Fix kwargs support in [#328](https://github.com/PyO3/pyo3/pull/328).
- Add full support for `__dict__` in [#403](https://github.com/PyO3/pyo3/pull/403).
- Bindings for the `datetime` standard library types: `PyDate`, `PyTime`, `PyDateTime`, `PyTzInfo`, `PyDelta` with associated `ffi` types, by pganssle [#200](https://github.com/PyO3/pyo3/pull/200).
- Upgraded to syn 0.14 which means much better error messages :tada:
- 128 bit integer support by [kngwyu](https://github.com/kngwyu) ([#137](https://github.com/PyO3/pyo3/pull/173))
-`proc_macro` has been stabilized on nightly ([rust-lang/rust#52081](https://github.com/rust-lang/rust/pull/52081)). This means that we can remove the `proc_macro` feature, but now we need the `use_extern_macros` from the 2018 edition instead.
- All proc macro are now prefixed with `py` and live in the prelude. This means you can use `#[pyclass]`, `#[pymethods]`, `#[pyproto]`, `#[pyfunction]` and `#[pymodinit]` directly, at least after a `use pyo3::prelude::*`. They were also moved into a module called `proc_macro`. You shouldn't use `#[pyo3::proc_macro::pyclass]` or other longer paths in attributes because `proc_macro_path_invoc` isn't going to be stabilized soon.
- Renamed the `base` option in the `pyclass` macro to `extends`.
-`#[pymodinit]` uses the function name as module name, unless the name is overrriden with `#[pymodinit(name)]`
