================
Cython Changelog
================

3.1.1 (2025-05-19)
==================

Bugs fixed
----------

* A reference leak in the async delegation code was fixed.
  (Github issues :issue:`6850`, :issue:`6878`)

* Conditional if-else expressions mixing Python and C (numeric) types could end up
  inferring an overly tight result type, thus leading to unexpected type conversions,
  runtime exceptions on assignment, or incorrect "temporary assignment" compile errors.
  (Github issue :issue:`6854`)

* Some Limited API issues were resolved.
  (Github issue :issue:`6862`)

* Large C ``long long`` values could be truncated when passed into PyPy.
  (Github issue :issue:`6890`)

* ``callable()`` incorrectly reported ``False`` in PyPy for classes with metaclasses.
  Patch by Anatolii Aniskovych. (Github issue :issue:`6892`)

* The signature of fused functions was no longer introspectable in Cython 3.1.0.
  (Github issue :issue:`6855`)

* Coroutines could generate invalid C with line tracing enabled.
  (Github issue :issue:`6865`)

* Code using ``complex()`` could generate invalid C code missing type declarations.
  (Github issue :issue:`6860`)

* Code using e.g. ``list[int | None]``  outside of variable/argument annotations failed to compile.
  (Github issue :issue:`6856`)

* Code using ctuples in a ``const`` context could generate invalid C.
  (Github issue :issue:`6864`)

* Accessing special methods on cpdef enums failed to compile.

* Some C compiler warnings were resolved.
  Patches by Daniel Larraz.  (Github issues :issue:`6876`, :issue:`3172`, :issue:`6873`, :issue:`6877`)

* Re-establish support for PyPy 3.8.
  (Github issue :issue:`6867`)


3.1.0 (2025-05-08)
==================

Other changes
-------------

* No functional changes since 3.1.0 rc 2.


3.1.0 rc 2 (2025-05-07)
=======================

Features added
--------------

* Declarations for C++ ``std::stop_token`` were added as ``libcpp.stop_token`` to provide
  additional low-level synchronisation primitives also in the light of free-threading Python.
  (Github issue :issue:`6820`)

* The generation of the shared module now happens automatically from ``cythonize()`` in a
  ``setuptools`` build if a corresponding ``Extension`` has been configured.
  This avoids an additional step outside of the ``setup.py`` or ``pip wheel`` run.
  (Github issue :issue:`6842`)

Bugs fixed
----------

* Variables typed as builtin Python exception types now accept subtypes instead of rejecting them.
  This specifically impacted types like ``BaseException``, ``Exception`` or ``OSError``,
  which almost always intend to reference subtypes.
  (Github issue :issue:`6828`)

* Functions with more than 10 constant default argument values could generate invalid C code.
  (Github issue :issue:`6843`)

* The ``call_once()`` function argument in ``libc.threads`` (new in 3.1) was changed to require
  a ``nogil`` declaration, as semantically implied.  Code that used it with a callback function
  expecting to hold the GIL must change the callback code to use ``with gil``.

* Calling cimported C functions with their fully qualified package name could crash Cython.
  (Github issue :issue:`6551`)

* Naming a variable after its inferred type (e.g. ``str += ""``) could trigger an infinite loop in Cython.
  (Github issue :issue:`6835`)

* Cython is more relaxed about the exact C++ constructor name when it calls ``new()`` on ctypedefs.
  (Github issue :issue:`6821`)

* Using ``cpp_locals`` in nogil sections could crash.
  (Github issue :issue:`6838`)

* ``const struct`` declarations could lead to invalid assignments to ``const`` temp variables.
  (Github issue :issue:`6804`)

* A refcounting error was fixed in the method class cell support code.
  (Github issue :issue:`6839`)


3.1.0 rc 1 (2025-05-01)
=======================

Features added
--------------

* ``cython.pymutex`` provides a fast mutex by wrapping the new ``PyMutex`` feature of recent
  CPython versions (including free-threading) and falls back to ``PyThread`` locks in older Pythons.
  (Github issue :issue:`6579`)

* A new directive ``subinterpreters_compatible=shared_gil/own_gil`` was added to allow modules
  to declare support for subinterpreters.
  (Github issue :issue:`6513`)

* ``divmod()`` is also optimised for C floating point types and can be called on C number types
  without holding the GIL.
  (Github issue :issue:`6801`)

* New C++ declarations were added.
  (Github issues :issue:`6625`, :issue:`6731`)

* ``embedsignature`` now works for special methods (if they have a docstring).
  (Github issue :issue:`1577`)

Bugs fixed
----------

* Iterating over literal sequences in generator expressions could generate invalid C code.
  (Github issue :issue:`6725`)

* Tracing could generate invalid C code.
  (Github issue :issue:`6781`)

* Non-ASCII function argument names could generate invalid C code.
  (Github issue :issue:`6813`)

* Optimised ``divmod()`` calls could produce incorrect results in beta-1 due to incorrect C type usage.
  (Github issue :issue:`6786`)

* Raising ``UnboundLocalError`` could fail for non-ascii variable names.
  (Github issue :issue:`6800`)

* The signature of ``PyByteArray_Resize()`` in ``cpython.bytearray`` failed to propagate exceptions.
  Patch by Kirill Smelkov.  (Github issue :issue:`6787`)

* Some more issues with the Limited C-API and free-threading Python were resolved.

  https://github.com/cython/cython/issues?q=label%3A%22limited+api%22

  https://github.com/cython/cython/issues?q=label%3A%22nogil+CPython%22

* The signature of ``cythonize_one()`` accidentally changed in 3.1.0b1.
  (Github issue :issue:`6815`)

Other changes
-------------

* Named ``cpdef enums`` no longer copy their item names into the global module namespace.
  This was considered unhelpful for named enums which already live in their own class namespace.
  In cases where the old behaviour was desired, users can add the following backwards compatible
  command after their enum class definition: ``globals().update(getattr(TheUserEnumClass, '__members__'))``.
  Anonymous enums still produce global item names, as before.
  (Github issue :issue:`4571`)


3.1.0 beta 1 (2025-04-03)
==========================

Features added
--------------

* Global ``cdef const …`` variables are supported.
  (Github issue :issue:`6542`)

* A new context manager / function decorator ``cython.critical_section`` was added
  wrapping Python's critical section C-API feature.
  (Github issues :issue:`6516`, :issue:`6577`)

* Some common Cython-internal code (currently only memoryview related) can now be extracted
  into a shared extension module to reduce the installed overall size of a package with many
  Cython compiled modules.
  (Github issue :issue:`2356`)

* The type of ``prange`` loop targets is now inferred.
  (Github issue :issue:`6585`)

* Extracting keyword arguments is faster in some cases.
  (Github issue :issue:`6683`)

* Calling ``divmod()`` on any C integer types is efficient.
  (Github issue :issue:`6717`)

* Some async/coroutine/vectorcall code has improved fast-paths.
  (Github issues :issue:`6732`, :issue:`6735`, :issue:`6736`, :issue:`6738`, :issue:`6742`, :issue:`6771`)

* Calls to Python builtins and extension types use the vectorcall protocol.
  (Github issue :issue:`6744`)

* Method calls use ``PyObject_VectorcallMethod()`` where possible.
  (Github issue :issue:`6747`)

* Some C-API shortcuts were (re-)added.
  (Github issue :issue:`6761`)

* Cython can avoid normalising exceptions in an `except` clause if it knows that they are unused.
  (Github issue :issue:`6601`)

* The ``cython`` command has a new option ``--cache`` to cache generated files.
  (Github issue :issue:`6091`)

* The ``cythonize`` command has a new option ``--timeit`` to benchmark Cython code snippets.
  (Github issue :issue:`6697`)

* The argument parsing ``cygdb`` command was improved based on ``argparse``.
  Patch by William Ayd.  (Github issue :issue:`5499`)

* The ``PyWeakref_GetRef`` declaration was added to ``cpython.weakref`` and backported.
  Patch by Lysandros Nikolaou.  (Github issue :issue:`6478`)

* ``std::span`` declarations were added to ``libcpp``.
  Patch by Alexander Condello.  (Github issue :issue:`6539`)

* ``std::string_view`` declarations were added to ``libcpp``.
  Patch by Antoine Pitrou.  (Github issue :issue:`6539`)

* Mutex declarations for ``libc`` and  ``libcpp`` were added.
  (Github issue :issue:`6610`)

* Several C++ declarations were improved and extended.
  Patches by Yury V. Zaytsev.  (Github issues :issue:`488`, :issue:`489`)

* Bazel build rules were updated for better interoperability.
  Patch by maleo.  (Github issue :issue:`6478`)

* The ``Demos/benchmarks/`` directory include a new benchmark runner that can run selected
  benchmarks against different Cython git revisions.

Bugs fixed
----------

* Many issues with the Limited C-API and free-threading Python were resolved.
  This includes better thread-safety of Cython-internal types like functions and generators.

  https://github.com/cython/cython/issues?q=label%3A%22limited+api%22

  https://github.com/cython/cython/issues?q=label%3A%22nogil+CPython%22

* ``for-in`` loops could generate invalid code for C++ containers.
  Patch by Taras Kozlov.  (Github issue :issue:`6578`)

* ``PyDict_GetItemRef()`` and ``PyList_GetItemRef()`` were not always used correctly.
  Patch by Lisandro Dalcin.  (Github issue :issue:`6647`)

* Inlined calls to local functions could crash with ``binding=False``.
  (Github issue :issue:`6556`)

* Calling ``sorted()`` could crash in 3.1.0a1.
  (Github issue :issue:`6496`)

* Calling 0-arg methods was unnecessarily slow in 3.1.0a1.
  (Github issue :issue:`6730`)

* A crash when reading the interpreter ID was fixed.

* Crashes while tracing C function returns were resolved.
  (Github issue :issue:`6503`)

* A compiler crash on ``complex/complex`` was resolved.
  (Github issue :issue:`6552`)

* A compiler crash when using the ``cpp_locals`` directive was resolved.
  (Github issue :issue:`6370`)

* Name mangling did not work correctly for attributes of extension types that have reserved C names.
  (Github issue :issue:`6678`)

* Declaring a ``@staticmethod`` in a pxd file and overriding it in a subclass could
  trigger incorrect "declared but not defined" errors.
  Patch by Aditya Pillai.  (Github issue :issue:`6714`)

* Cython's fake code objects are now compatible with GraalPython.
  (Github issue :issue:`6409`)

* Stepping through foreign code with ``cygdb`` could fail with an ``IndexError``.
  Patch by clayote.  (Github issue :issue:`6552`)

* Some PyPy incompatibilities were resolved.
  Patches by Matti Picus.  (Github issue :issue:`6592`,  :issue:`6640`)

* Interoperability with recent Pythran releases was fixed.
  (Github issue :issue:`6494`)

* The ``gdb`` compatibility of ``cygdb`` was improved.
  Patch by Kent Slaney.  (Github issue :issue:`6681`)

* Some redundant exception normalisation work was removed in Python 3.12+.
  (Github issue :issue:`6599`)

* A compiler hang introduced in 3.1a1 when overriding methods was resolved.
  Patch by Aditya Pillai.  (Github issue :issue:`6704`)

* A compiler crash was resolved when trying to issue a warning.
  Patch by Gabriele N. Tornetta.  (Github issue :issue:`6711`)

* Some incomplete import time "safety checks" from 3.1.0a1 were removed again.
  (Github issue :issue:`6671`)

* Using the ``common_utility_include_dir`` option in parallel builds on Windows could fail.

* Some "unused" warnings from the C compiler were resolved.
  Patches by Lisandro Dalcin.  (Github issue :issue:`6726`)

Other changes
-------------

* All Cython-internal types (functions, coroutines, …) are now heap types and use type specs.
  (Github issue :issue:`6633`)

* Tracing/monitoring is now disabled in parallel/prange sections.
  (Github issue :issue:`6709`)

* The ``numpy.math`` cimport module has been deprecated.
  Usages should be replaced by ``libc.math``.
  (Github issue :issue:`6743`)

* Includes all fixes as of Cython 3.0.12.


3.1.0 alpha 1 (2024-11-08)
==========================

Features added
--------------

* Support for freethreading builds of CPython 3.13 was added.
  It comes with a new directive ``freethreading_compatible=True`` to mark modules as
  free-threading compatible (``Py_mod_gil``).

  https://github.com/cython/cython/issues?q=label%3A%22nogil+CPython%22

  Patches by Lysandros Nikolaou and Nathan Goldbaum.  (Github issue :issue:`6162`)

* Support for monitoring Cython modules via `sys.monitoring` in CPython 3.13+ was added.
  For coverage reporting, this needs to be disabled with `-DCYTHON_USE_SYS_MONITORING=0`
  as long as `coverage.py` does not support `sys.monitoring` for coverage plugins.
  (Github issue :issue:`6144`)

* Many issues with the Limited C-API were resolved.
  It is now sufficient to define the macro ``Py_LIMITED_API`` to activate the support.

  https://github.com/cython/cython/issues?q=label%3A%22limited+api%22

* Support for GraalPython was improved (but is still incomplete).

* Several issues with the gdb support were resolved.
  Patches by Kent Slaney.  (Github issues :issue:`5955`, :issue:`5948`)

* ``typing.Union[SomeType, None]`` and ``SomeType | None`` are now understood and mean
  the same as ``typing.Optional[SomeType]``, allowing ``None`` in type checks.
  (Github issue :issue:`6254`)

* ``cython.const[]`` and ``cython.volatile[]`` are now available as type modifiers in Python code.
  (Github issue :issue:`5728`)

* ``cython.pointer[SomeCType]`` can now be used to define pointer types in Python type annotations.
  (Github issue :issue:`5071`)

* Several improvements were made to reduce the size of the resulting extension modules.
  (Github issue :issue:`4425`)

* Function calls now use the PEP-590 Vectorcall protocol, even when passing keyword arguments.
  (Github issues :issue:`5804`)

* Coroutines now use the ``am_send`` slot function instead of going through a Python ``.send()`` call.
  This has been backported for Python 3.7 - 3.9.
  (Github issues :issue:`4585`)

* ``__set_name__`` is called when assigning to class attributes.
  (Github issue :issue:`6179`)

* Most builtin methods now provide their return type for type inference.
  (Github issues :issue:`4829`, :issue:`5865`, :issue:`6412`)

* Method calls on builtin literal values are evaluated at compile time, if applicable.
  (Github issue :issue:`6383`)

* The Python ``int`` type now maps directly to ``PyLong`` and is inferred accordingly.
  (Github issue :issue:`4237`)

* Integer operations on known ``int`` types are faster.
  (Github issue :issue:`5785`)

* f-strings are faster in some cases.
  (Github issues :issue:`5866`, :issue:`6342`, :issue:`6383`)

* ``divmod()`` is faster on C ``int``.
  Patch by Tong He.  (Github issue :issue:`6073`)

* ``dict.pop()`` is faster in some cases.
  (Github issue :issue:`5911`)

* ``.isprintable()`` is optimised for Unicode characters.
  (Github issue :issue:`3277`)

* ``x in ()`` and similar tests against empty constant sequences (e.g. in generated code)
  are now discarded if they have no side-effects.
  (Github issue :issue:`6288`)

* Constant (non-GC) Python objects are no longer traversed with ``Py_VISIT()`` during GC runs.
  (Github issue :issue:`6277`)

* C++ classes implemented in Cython can now use method overloading.
  Patch by samaingw.  (Github issue :issue:`3235`)

* Assigning a Python container to a C++ vector now makes use of ``__length_hint__``
  to avoid reallocations.
  Patch by Denis Lukianov.  (Github issue :issue:`6077`)

* The C++11 ``emplace*`` methods were added to ``libcpp.deque``.
  Patch by Somin An.  (Github issue :issue:`6159`)

* ``cpython.time`` was updated and extended for Python 3.13.
  (Github issue :issue:`6187`)

* Dataclasses support the ``match_args`` option.
  (Github issue :issue:`5381`)

* Threading in parallel sections can now be disabled with a new ``use_threads_if`` condition.
  (Github issue :issue:`5919`)

* New options ``warn.deprecated.DEF`` and ``warn.deprecated.IF`` can silence the deprecation warnings.
  Patch by Eric Larson.  (Github issue :issue:`6243`)

* ``cygdb`` shows more helpful output for some objects.
  Patch by Kent Slaney.  (Github issue :issue:`5958`)

* Bazel build support for improved.
  Patch by mering.  (Github issue :issue:`6452`)

* The parser was updated for Unicode 15.1 (as provided by CPython 3.13b4).

Bugs fixed
----------

* C functions used different start lines and columns for error reporting and tracing
  than Python functions.  They now use the line and column of their first decorator
  or (if none) their definition line, as in Python.
  (Github issue :issue:`6366`)

* Dataclasses did not handle default fields without init value correctly.
  (Github issue :issue:`5858`)

* Implementing a special method based on another could lead to infinite recursion.
  (Github issue :issue:`5863`)

* The ``__class__`` cell variable in methods was not always working as in Python.
  Initial patch by Tom Keefe.  (Github issue :issue:`2912`)

* Lambda functions had no code objects. Their signature can now be introspected.
  (Github issue :issue:`2983`)

* Subtyping `complex` as extension type could fail.
  (Github issue :issue:`6346`)

* ``hasattr()`` now propagates exceptions that occur during lookup.
  (Github issue :issue:`6269`)

* The base type of extension heap types is now traversed during GC runs in Py3.9+.
  (Github issue :issue:`4193`)

* The Python ``&`` operator could touch invalid memory with certain ``0`` values in Python <= 3.10.
  Patch by Michael J. Sullivan.  (Github issue :issue:`4193`)

* Exception values were not always recognised as equal at compile time.
  (Github issue :issue:`5709`)

* Running Cython in different Python versions could generate slightly different C code
  due to differences in the builtins.
  (Github issue :issue:`5591`)

* The `common_include_dir` feature used different file paths in the C code on Windows and Posix.
  It now uses forward slashes as directory separator consistently.
  (Github issue :issue:`6355`)

* File paths in the C code are now relative to the build directory.
  Patch by Oscar Benjamin.  (Github issue :issue:`6341`)

* depfiles now use relative paths whenever possible.
  Patch by Loïc Estève.  (Github issue :issue:`6345`)

* The ``-a`` option in the IPython magic no longer copies the complete HTML document
  into the notebook but only a more reasonable content snippet.
  Patch by Min RK.  (Github issue :issue:`5760`)

* Uselessly referring to C enums (not enum values) as Python objects is now rejected.
  Patch by Vyas Ramasubramani.  (Github issue :issue:`5638`)

* Cython no longer acquires the GIL during in-place assignments to C attributes in nogil sections.
  Patch by Mads Ynddal.  (Github issue :issue:`6407`)

* Several C++ warnings about ``char*`` casts were resolved.
  (Github issues :issue:`5515`, :issue:`5847`)

* C++ undefined behaviour was fixed in an error handling case.
  (Github issue :issue:`5278`)

* Dict assignments to struct members with reserved C/C++ names could generate invalid C code.

* The PEP-479 implementation could raise a visible ``RuntimeError`` without
  a trace of the original ``StopIteration``.
  (Github issue :issue:`5953`)

* A crash was fixed when assigning a zero-length slice to a memoryview.
  Patch by Michael Man.  (Github issue :issue:`6227`)

* Conditionally assigning to variables with the walrus operator could crash.
  (Github issue :issue:`6094`)

* Unterminated string literals could lock up the build in an infinite loop.
  (Github issue :issue:`5977`)

* Exporting C functions uses better platform compatible code.
  (Github issue :issue:`4683`)

* The shebang in ``libpython.py`` was incorrect.
  Patch by Luke Hamburg.  (Github issue :issue:`6439`)

* Cython now uses `SHA-256` instead of `SHA-1` for caching etc. as the latter may not be
  available on all Python installations.
  (Github issue :issue:`6354`)

Other changes
-------------

* Support for Python 2.7 - 3.7 was removed, along with large chunks of legacy code.
  (Github issue :issue:`2800`)

* The pxd files ``cpython.int``, ``cpython.cobject``, ``cpython.oldbuffer`` and ``cpython.string``
  were removed as they refer to C-API declarations that are only in Python 2.x.
  (Github issue :issue:`5870`)

* The generated C code now requires a C99 compatible C compiler.

* ``language_level=3`` is now the default.
  ``language_level=3str`` has become a legacy alias.
  (Github issue :issue:`5827`)

* The Py2 types ``unicode`` and ``basestring`` are now deprecated and have become aliases
  of the ``str`` type.
  (Github issue :issue:`6374`)

* Docstrings now strip their leading whitespace according to PEP-257.
  Patch by Lawrence Mitchell.  (Github issue :issue:`6241`)

* Type checkers should have it easier to find and validate Cython types in .py files.
  (Github issue :issue:`4327`)

* The previously shipped NumPy C-API declarations (``cimport numpy``) were removed.
  NumPy has been providing version specific declarations for several versions now.
  (Github issue :issue:`5842`)

* Usages of the outdated ``WITH_THREAD`` macro guard were removed.
  (Github issue :issue:`5812`)

* The options for showing the C code line in Python exception stack traces were cleaned up.
  Previously, disabling the option with the ``CYTHON_CLINE_IN_TRACEBACK`` macro did not
  reduce the code overhead of the feature, and the ``c_line_in_traceback`` compile option
  was partly redundant with the C macro switches and lead to warnings about unused code.
  Since this is considered mostly a debug feature, the new default is that it is _disabled_
  to avoid code and runtime overhead.  It can be enabled by setting the C macro to 1, and
  a new macro ``CYTHON_CLINE_IN_TRACEBACK_RUNTIME`` was added that controls the runtime
  configurable setting if the feature is enabled, which was previously only available
  through the compile option.  The compile option is now deprecated (but still available),
  and users should migrate to using the two C macros only.
  (Github issue :issue:`6036`)

* Includes all fixes as of Cython 3.0.11 (but generates C99 code in some places).


3.0.12 (2025-02-11)
===================

Bugs fixed
----------

* Release 3.0.11 introduced some incorrect ``noexcept`` warnings.
  (Github issue :issue:`6335`)

* Conditional assignments to variables using the walrus operator could crash.
  (Github issue :issue:`6094`)

* Dict assignments to struct members with reserved C names could generate invalid C code.

* Fused ctuples with the same entry types but different sizes could fail to compile.
  (Github issue :issue:`6328`)

* In Py3, `pyximport` was not searching `sys.path` when looking for importable source files.
  (Github issue :issue:`5615`)

* Using `& 0` on integers produced with `int.from_bytes()` could read invalid memory on Python 3.10.
  (Github issue :issue:`6480`)

* Modules could fail to compile in PyPy 3.11 due to missing CPython specific header files.
  Patch by Matti Picus.  (Github issue :issue:`6482`)

* Minor fix in C++ ``partial_sum()`` declaration.


3.0.11 (2024-08-05)
===================

Features added
--------------

* The C++11 ``emplace*`` methods were added to ``libcpp.deque``.
  Patch by Somin An.  (Github issue :issue:`6159`)

Bugs fixed
----------

* The exception check value of functions declared in pxd files was not always applied in 3.0.10.
  (Github issue :issue:`6122`)

* A crash on exception deallocations was fixed.
  (Github issue :issue:`6022`)

* A crash was fixed when assigning a zero-length slice to a memoryview.
  Patch by Michael Man.  (Github issue :issue:`6227`)

* ``libcpp.optional.value()`` could crash if it raised a C++ exception.
  Patch by Alexander Condello.  (Github issue :issue:`6190`)

* The return type of ``str()`` was mishandled, leading to crashes with ``language_level=3``.
  (Github issue :issue:`6166`)

* ``bytes.startswith/endswith()`` failed for non-bytes substrings (e.g. ``bytearray``).
  (Github issue :issue:`6168`)

* Fused ctuples crashed Cython.
  (Github issue :issue:`6068`)

* A compiler crash was fixed when using extension types in fused types.
  (Github issue :issue:`6204`)

* The module cleanup code was incorrect for globally defined memory view slices.
  (Github issue :issue:`6276`)

* Some adaptations were made to enable compilation in Python 3.13.
  (Github issues :issue:`5997`, :issue:`6182`, :issue:`6251`)


3.0.10 (2024-03-30)
===================

Bugs fixed
----------

* Cython generated incorrect self-casts when directly calling final methods of subtypes.
  Patch by Lisandro Dalcin.  (Github issue :issue:`2747`)

* Internal C names generated from C function signatures could become too long for MSVC.
  (Github issue :issue:`6052`)

* The ``noexcept`` warnings could be misleading in some cases.
  Patch by Gonzalo Tornaría.  (Github issue :issue:`6087`)

* The ``@cython.ufunc`` implementation could generate incomplete C code.
  (Github issue :issue:`6064`)

* The ``libcpp.complex`` declarations could result in incorrect C++ code.
  Patch by Raffi Enficiaud.  (Github issue :issue:`6037`)

* Several tests were adapted to work with both NumPy 1.x and 2.0.
  Patch by Matti Picus.  (Github issues :issue:`6076`, :issue:`6100`)

* C compiler warnings when the freelist implementation is disabled (e.g. on PyPy) were fixed.
  It can now be disabled explicitly with the C macro guard ``CYTHON_USE_FREELISTS=0``.
  (Github issue :issue:`6099`)

* Some C macro guards for feature flags were missing from the NOGIL Python configuration.

* Some recently added builtins were unconditionally looked up at module import time
  (if used by user code) that weren't available on all Python versions and could thus
  fail the import.

* A performance hint regarding exported pxd declarations was improved.
  (Github issue :issue:`6001`)


3.0.9 (2024-03-05)
==================

Features added
--------------

* Assigning ``const`` values to non-const variables now issues a warning.
  (Github issue :issue:`5639`)

* Using ``noexcept`` on a function returning Python objects now issues a warning.
  (Github issue :issue:`5661`)

* Some C-API usage was updated for the upcoming CPython 3.13.
  Patches by Victor Stinner et al.  (Github issues :issue:`6003`, :issue:`6020`)

* The deprecated ``Py_UNICODE`` type is no longer used, unless required by user code.
  (Github issue :issue:`5982`)

* ``std::string.replace()`` declarations were added to libcpp.string.
  Patch by Kieran Geary.  (Github issue :issue:`6037`)

Bugs fixed
----------

* Cython generates incorrect (but harmless) self-casts when directly calling
  final methods of subtypes.  Lacking a better solution, the errors that recent
  gcc versions produce have been silenced for the time being.
  Original patch by Michał Górny.  (Github issue :issue:`2747`)

* Unused variable warnings about clineno were fixed when C lines in tracebacks are disabled.
  (Github issue :issue:`6035`)

* Subclass deallocation of extern classes could crash if the base class uses GC.
  Original patch by Jason Fried.  (Github issue :issue:`5971`)

* Type checks for Python ``memoryview`` could use an invalid C function.
  Patch by Xenia Lu.  (Github issue :issue:`5988`)

* Calling final fused functions could generate invalid C code.
  (Github issue :issue:`5989`)

* Declaring extern enums multiple times could generate invalid C code.
  (Github issue :issue:`5905`)

* ``pyximport`` used relative paths incorrectly.
  Patch by Stefano Rivera.  (Github issue :issue:`5957`)

* Running Cython with globbing characters (``[]*?``) in the module search path could fail.
  Patch by eewanco.  (Github issue :issue:`5942`)

* Literal strings that include braces could change the C code indentation.

Other changes
-------------

* The "enum class not importable" warning is now only issued once per enum type.
  (Github issue :issue:`5941`)


3.0.8 (2024-01-10)
==================

Bugs fixed
----------

* Using ``const`` together with defined fused types could fail to compile.
  (Github issue :issue:`5230`)

* A "use after free" bug was fixed in parallel sections.
  (Github issue :issue:`5922`)

* Several types were not available as ``cython.*`` types in pure Python code.

* The generated code is now correct C89 again, removing some C++ style ``//`` comments
  and C99-style declaration-after-code code ordering.  This is still relevant for some
  ols C compilers, specifically ones that match old Python 2.7 installations.


3.0.7 (2023-12-19)
==================

Bugs fixed
----------

* In the iterator of generator expressions, ``await`` and ``yield`` were not correctly analysed.
  (Github issue :issue:`5851`)

* ``cpdef`` enums with the same name cimported from different modules could lead to
  invalid C code.
  (Github issue :issue:`5887`)

* Some declarations in ``cpython.unicode`` were fixed and extended.
  (Github issue :issue:`5902`)

* Compiling fused types used in pxd files could crash Cython in Python 3.11+.
  (Github issues :issue:`5894`,  :issue:`5588`)

* Source files with non-ASCII file names could crash Cython.
  (Github issue :issue:`5873`)

* Includes all bug-fixes and features from the 0.29 maintenance branch
  up to the :ref:`0.29.37` release.


3.0.6 (2023-11-26)
==================

Features added
--------------

* Fused def function dispatch is a bit faster.

* Declarations for the ``wchar`` PyUnicode API were added.
  (Github issue :issue:`5836`)

* The Python "nogil" fork is now also detected with the new ``Py_GIL_DISABLED`` macro.
  Patch by Hugo van Kemenade.  (Github issue :issue:`5852`)

Bugs fixed
----------

* Comparing dataclasses could give different results than Python.
  (Github issue :issue:`5857`)

* ``float(std::string)`` generated invalid C code.
  (Github issue :issue:`5818`)

* Using ``cpdef`` functions with ``cimport_from_pyx`` failed.
  (Github issue :issue:`5795`)

* A crash was fixed when string-formatting a Python value fails.
  (Github issue :issue:`5787`)

* On item access, Cython could try the sequence protocol before the mapping protocol
  in some cases if an object supports both.
  (Github issue :issue:`5776`)

* A C compiler warning was resolved.
  (Github issue :issue:`5794`)

* Complex numbers failed to compile in MSVC with C11.
  Patch by Lysandros Nikolaou.  (Github issue :issue:`5809`)

* Some issues with the Limited API and with PyPy were resolved.
  (Github issues :issue:`5695`, :issue:`5696`)

* A C++ issue in Python 3.13 was resolved.
  (Github issue :issue:`5790`)

* Several directives are now also available (as no-ops) in Python code.
  (Github issue :issue:`5803`)

* An error message was corrected.
  Patch by Mads Ynddal.  (Github issue :issue:`5805`)


3.0.5 (2023-10-31)
==================

Features added
--------------

* Preliminary support for CPython 3.13a1 was added to allow early testing.
  (Github issue :issue:`5767`)

Bugs fixed
----------

* A compiler crash was fixed.
  (Github issue :issue:`5771`)

* A typo in the ``always_allow_keywords`` directive for Python code was fixed.
  Patch by lk-1984.  (Github issue :issue:`5772`)

* Some C compiler warnings were resolved.
  Patch by Pierre Jolivet.  (Github issue :issue:`5780`)


3.0.4 (2023-10-17)
==================

Features added
--------------

* A new compiler directive ``show_performance_hints`` was added to disable the
  newly added performance hint output.
  (Github issue :issue:`5748`)

Bugs fixed
----------

* ```cythonize` required ``distutils`` even for operations that did not build binaries.
  (Github issue :issue:`5751`)

* A regression in 3.0.3 was fixed that prevented calling inline functions
  from another inline function in ``.pxd`` files.
  (Github issue :issue:`5748`)

* Some C compiler warnings were resolved.
  Patch by Pierre Jolivet.  (Github issue :issue:`5756`)


3.0.3 (2023-10-05)
==================

Features added
--------------

* More warnings were added to help users migrate and avoid bugs.
  (Github issue :issue:`5650`)

* A warning-like category for performance hints was added that bypasses ``-Werror``.
  (Github issue :issue:`5673`)

* FastGIL now uses standard ``thread_local`` in C++.
  (Github issue :issue:`5640`)

* ``reference_wrapper`` was added to ``libcpp.functional``.
  Patch by Vyas Ramasubramani.  (Github issue :issue:`5671`)

* The ``cythonize`` command now supports the ``--cplus`` option known from the ``cython`` command.
  (Github issue :issue:`5736`)

Bugs fixed
----------

* Performance regressions where the GIL was needlessly acquired were fixed.
  (Github issues :issue:`5670`, :issue:`5700`)

* A reference leak for exceptions in Python 3.12 was resolved.
  Patch by Eric Johnson.  (Github issue :issue:`5724`)

* ``fastcall`` calls with keyword arguments generated incorrect C code.
  (Github issue :issue:`5665`)

* Assigning the type converted result of a conditional (if-else) expression
  to ``int`` or ``bool`` variables could lead to incorrect C code.
  (Github issue :issue:`5731`)

* Early (unlikely) failures in Python function wrappers no longer set a
  traceback in order to simplify the C code flow.  Being mostly memory
  allocation errors, they probably would never have created a traceback anyway.
  (Github issue :issue:`5681`)

* Relative cimports from packages with ``__init__.py`` files could fail.
  (Github issue :issue:`5715`)

* Several issues with the Limited API support were resolved.
  (Github issues :issue:`5641`, :issue:`5648`, :issue:`5689`)

* The code generated for special-casing both Cython functions and PyCFunctions was cleaned up
  to avoid calling C-API functions that were not meant for the other type respectively.
  This could previously trigger assertions in CPython debug builds and now also plays better
  with the Limited API.
  (Github issues :issue:`4804`, :issue:`5739`)

* Fix some C compiler warnings.
  Patches by Ralf Gommers, Oleksandr Pavlyk, Sebastian Koslowski et al.
  (Github issues :issue:`5651`, :issue:`5663`, :issue:`5668`, :issue:`5717`, :issue:`5726`, :issue:`5734`)

* Generating gdb debugging information failed when using generator expressions.
  Patch by Oleksandr Pavlyk.  (Github issue :issue:`5552`)

* Passing a ``setuptools.Extension`` into ``cythonize()`` instead of a
  ``distutils.Extension`` could make it miss the matching extensions.

* ``cython -M`` needlessly required ``distutils``, which made it fail in Python 3.12.
  (Github issue :issue:`5681`)

Other changes
-------------

* The visible deprecation warning for ``DEF`` was removed again since it proved
  difficult for some users to migrate away from it.  The statement is still
  meant to be removed at some point (and thus, like ``IF``, should not be
  used in new code), but the time for sunset is probably not around the corner.
  (Github issue :issue:`4310`)

* The ``np_pythran`` option raise a ``DeprecationWarning`` if it receives other values
  than ``True`` and ``False``.  This will eventually be disallowed (in line with all
  other boolean options).


3.0.2 (2023-08-27)
==================

Bugs fixed
----------

* Using ``None`` as default value for arguments annotated as ``int`` could crash Cython.
  (Github issue :issue:`5643`)

* Default values of fused types that include ``complex`` could generate invalid C code
  with ``-DCYTHON_CCOMPLEX=0``.
  (Github issue :issue:`5644`)

* Using C++ enum class types in extension type method signatures could generate invalid C code.
  (Github issue :issue:`5637`)


3.0.1 (2023-08-25)
==================
