- 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` and `PyDateTime_TimeZone_UTC` are are now unsafe functions instead of statics. [#2126](https://github.com/PyO3/pyo3/pull/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 behaviour: [#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` enviroment 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 unneccessary rebuilds when cycling between `cargo check` and `cargo clippy` in a Python virtualenv. [#1557](https://github.com/PyO3/pyo3/pull/1557)
- Fix segfault when dereferencing `ffi::PyDateTimeAPI` without the GIL. [#1563](https://github.com/PyO3/pyo3/pull/1563)
- 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 613](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 behaviour 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)
- Fixed unsoundness of subclassing. [#683](https://github.com/PyO3/pyo3/pull/683).
- Clear error indicator when the exception is handled on the Rust side. [#719](https://github.com/PyO3/pyo3/pull/719)
- Usage of raw identifiers with `#[pyo3(set)]`. [#745](https://github.com/PyO3/pyo3/pull/745)
- Usage of `PyObject` with `#[pyo3(get)]`. [#760](https://github.com/PyO3/pyo3/pull/760)
-`#[pymethods]` used in conjunction with `#[cfg]`. #[769](https://github.com/PyO3/pyo3/pull/769)
-`"*"` in a `#[pyfunction()]` argument list incorrectly accepting any number of positional arguments (use `args = "*"` when this behaviour 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)]`
