Metadata-Version: 2.4
Name: Cython
Version: 3.1.0
Summary: The Cython compiler for writing C extensions in the Python language.
Home-page: https://cython.org/
Author: Robert Bradshaw, Stefan Behnel, David Woods, Greg Ewing, et al.
Author-email: cython-devel@python.org
License: Apache-2.0
Project-URL: Documentation, https://cython.readthedocs.io/
Project-URL: Donate, https://cython.readthedocs.io/en/latest/src/donating.html
Project-URL: Source Code, https://github.com/cython/cython
Project-URL: Bug Tracker, https://github.com/cython/cython/issues/
Project-URL: User Group, https://groups.google.com/g/cython-users
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: 3.9
Classifier: Programming Language :: Python :: 3.10
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Programming Language :: Python :: Implementation :: Stackless
Classifier: Programming Language :: C
Classifier: Programming Language :: C++
Classifier: Programming Language :: Cython
Classifier: Topic :: Software Development :: Code Generators
Classifier: Topic :: Software Development :: Compilers
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Typing :: Typed
Requires-Python: >=3.8
License-File: LICENSE.txt
License-File: COPYING.txt
Dynamic: author
Dynamic: author-email
Dynamic: classifier
Dynamic: description
Dynamic: home-page
Dynamic: license
Dynamic: license-file
Dynamic: project-url
Dynamic: requires-python
Dynamic: summary

The Cython language makes writing C extensions for the Python language as
easy as Python itself.  Cython is a source code translator based on Pyrex_,
but supports more cutting edge functionality and optimizations.

The Cython language is a superset of the Python language (almost all Python
code is also valid Cython code), but Cython additionally supports optional
static typing to natively call C functions, operate with C++ classes and
declare fast C types on variables and class attributes.  This allows the
compiler to generate very efficient C code from Cython code.

This makes Cython the ideal language for writing glue code for external
C/C++ libraries, and for fast C modules that speed up the execution of
Python code.

The newest Cython release can always be downloaded from https://cython.org/.
Unpack the tarball or zip file, enter the directory, and then run::

    pip install .

Note that for one-time builds, e.g. for CI/testing, on platforms that are not
covered by one of the wheel packages provided on PyPI *and* the pure Python wheel
that we provide is not used, it is substantially faster than a full source build
to install an uncompiled (slower) version of Cython with::

    NO_CYTHON_COMPILE=true pip install .

.. _Pyrex: https://www.cosc.canterbury.ac.nz/greg.ewing/python/Pyrex/

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

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

3.1.0 rc 2 (2025-05-07):

* 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 https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6842)

3.1.0 rc 1 (2025-05-01):

* ``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 https://github.com/cython/cython/issues/6579)

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

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

* New C++ declarations were added.
  (Github issues https://github.com/cython/cython/issues/6625, https://github.com/cython/cython/issues/6731)

* ``embedsignature`` now works for special methods (if they have a docstring).
  (Github issue https://github.com/cython/cython/issues/1577)

3.1.0 beta 1 (2025-04-03):

* Global ``cdef const …`` variables are supported.
  (Github issue https://github.com/cython/cython/issues/6542)

* A new context manager / function decorator ``cython.critical_section`` was added
  wrapping Python's critical section C-API feature.
  (Github issues https://github.com/cython/cython/issues/6516, https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/2356)

* The type of ``prange`` loop targets is now inferred.
  (Github issue https://github.com/cython/cython/issues/6585)

* Extracting keyword arguments is faster in some cases.
  (Github issue https://github.com/cython/cython/issues/6683)

* Calling ``divmod()``on any C integer types is efficient.
  (Github issue https://github.com/cython/cython/issues/6717)

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

* Calls to Python builtins and extension types use the vectorcall protocol.
  (Github issue https://github.com/cython/cython/issues/6744)

* Method calls use ``PyObject_VectorcallMethod()`` where possible.
  (Github issue https://github.com/cython/cython/issues/6747)

* Some C-API shortcuts were (re-)added.
  (Github issue https://github.com/cython/cython/issues/6761)

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

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

* The ``cythonize`` command has a new option ``--timeit`` to benchmark Cython code snippets.
  (Github issue https://github.com/cython/cython/issues/6697)

* The argument parsing ``cygdb`` command was improved based on ``argparse``.
  Patch by William Ayd.  (Github issue https://github.com/cython/cython/issues/5499)

* The ``PyWeakref_GetRef`` declaration was added to ``cpython.weakref`` and backported.
  Patch by Lysandros Nikolaou.  (Github issue https://github.com/cython/cython/issues/6478)

* ``std::span`` declarations were added to ``libcpp``.
  Patch by Alexander Condello.  (Github issue https://github.com/cython/cython/issues/6539)

* ``std::string_view`` declarations were added to ``libcpp``.
  Patch by Antoine Pitrou.  (Github issue https://github.com/cython/cython/issues/6539)

* Mutex declarations for ``libc`` and  ``libcpp`` were added.
  (Github issue https://github.com/cython/cython/issues/6610)

* Several C++ declarations were improved and extended.
  Patches by Yury V. Zaytsev.  (Github issues https://github.com/cython/cython/issues/488, https://github.com/cython/cython/issues/489)

* Bazel build rules were updated for better interoperability.
  Patch by maleo.  (Github issue https://github.com/cython/cython/issues/6478)

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

3.1.0 alpha 1 (2024-11-08):

* 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 https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/5955, https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6254)

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

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

* Several improvements were made to reduce the size of the resulting extension modules.
  (Github issue https://github.com/cython/cython/issues/4425)

* Function calls now use the PEP-590 Vectorcall protocol, even when passing keyword arguments.
  (Github issues https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/4585)

* ``__set_name__`` is called when assigning to class attributes.
  (Github issue https://github.com/cython/cython/issues/6179)

* Most builtin methods now provide their return type for type inference.
  (Github issues https://github.com/cython/cython/issues/4829, https://github.com/cython/cython/issues/5865, https://github.com/cython/cython/issues/6412)

* Method calls on builtin literal values are evaluated at compile time, if applicable.
  (Github issue https://github.com/cython/cython/issues/6383)

* The Python ``int`` type now maps directly to ``PyLong`` and is inferred accordingly.
  (Github issue https://github.com/cython/cython/issues/4237)

* Integer operations on known ``int`` types are faster.
  (Github issue https://github.com/cython/cython/issues/5785)

* f-strings are faster in some cases.
  (Github issues https://github.com/cython/cython/issues/5866, https://github.com/cython/cython/issues/6342, https://github.com/cython/cython/issues/6383)

* ``divmod()`` is faster on C ``int``.
  Patch by Tong He.  (Github issue https://github.com/cython/cython/issues/6073)

* ``dict.pop()`` is faster in some cases.
  (Github issue https://github.com/cython/cython/issues/5911)

* ``.isprintable()`` is optimised for Unicode characters.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6288)

* Constant (non-GC) Python objects are no longer traversed with ``Py_VISIT()`` during GC runs.
  (Github issue https://github.com/cython/cython/issues/6277)

* C++ classes implemented in Cython can now use method overloading.
  Patch by samaingw.  (Github issue https://github.com/cython/cython/issues/3235)

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

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

* ``cpython.time`` was updated and extended for Python 3.13.
  (Github issue https://github.com/cython/cython/issues/6187)

* Dataclasses support the ``match_args`` option.
  (Github issue https://github.com/cython/cython/issues/5381)

* Threading in parallel sections can now be disabled with a new ``use_threads_if`` condition.
  (Github issue https://github.com/cython/cython/issues/5919)

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

* ``cygdb`` shows more helpful output for some objects.
  Patch by Kent Slaney.  (Github issue https://github.com/cython/cython/issues/5958)

* Bazel build support for improved.
  Patch by mering.  (Github issue https://github.com/cython/cython/issues/6452)

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

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

3.1.0 rc 2 (2025-05-07):

* 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 https://github.com/cython/cython/issues/6828)

* Functions with more than 10 constant default argument values could generate invalid C code.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6551)

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

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

* Using ``cpp_locals`` in nogil sections could crash.
  (Github issue https://github.com/cython/cython/issues/6838)

* ``const struct`` declarations could lead to invalid assignments to ``const`` temp variables.
  (Github issue https://github.com/cython/cython/issues/6804)

* A refcounting error was fixed in the method class cell support code.
  (Github issue https://github.com/cython/cython/issues/6839)

3.1.0 rc 1 (2025-05-01):

* Iterating over literal sequences in generator expressions could generate invalid C code.
  (Github issue https://github.com/cython/cython/issues/6725)

* Tracing could generate invalid C code.
  (Github issue https://github.com/cython/cython/issues/6781)

* Non-ASCII function argument names could generate invalid C code.
  (Github issue https://github.com/cython/cython/issues/6813)

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

* Raising ``UnboundLocalError`` could fail for non-ascii variable names.
  (Github issue https://github.com/cython/cython/issues/6800)

* The signature of ``PyByteArray_Resize()`` in ``cpython.bytearray`` failed to propagate exceptions.
  Patch by Kirill Smelkov.  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6815)

3.1.0 beta 1 (2025-04-03):

* 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 https://github.com/cython/cython/issues/6578)

* ``PyDict_GetItemRef()`` and ``PyList_GetItemRef()`` were not always used correctly.
  Patch by Lisandro Dalcin.  (Github issue https://github.com/cython/cython/issues/6647)

* Inlined calls to local functions could crash with ``binding=False``.
  (Github issue https://github.com/cython/cython/issues/6556)

* Calling ``sorted()`` could crash in 3.1.0a1.
  (Github issue https://github.com/cython/cython/issues/6496)

* Calling 0-arg methods was unnecessarily slow in 3.1.0a1.
  (Github issue https://github.com/cython/cython/issues/6730)

* A crash when reading the interpreter ID was fixed.

* Crashes while tracing C function returns were resolved.
  (Github issue https://github.com/cython/cython/issues/6503)

* A compiler crash on ``complex/complex`` was resolved.
  (Github issue https://github.com/cython/cython/issues/6552)

* A compiler crash when using the ``cpp_locals`` directive was resolved.
  (Github issue https://github.com/cython/cython/issues/6370)

* Name mangling did not work correctly for attributes of extension types that have reserved C names.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6714)

* Cython's fake code objects are now compatible with GraalPython.
  (Github issue https://github.com/cython/cython/issues/6409)

* Stepping through foreign code with ``cygdb`` could fail with an ``IndexError``.
  Patch by clayote.  (Github issue https://github.com/cython/cython/issues/6552)

* Some PyPy incompatibilities were resolved.
  Patches by Matti Picus.  (Github issue https://github.com/cython/cython/issues/6592,  https://github.com/cython/cython/issues/6640)

* Interoperability with recent Pythran releases was fixed.
  (Github issue https://github.com/cython/cython/issues/6494)

* The ``gdb`` compatibility of ``cygdb`` was improved.
  Patch by Kent Slaney.  (Github issue https://github.com/cython/cython/issues/6681)

* Some redundant exception normalisation work was removed in Python 3.12+.
  (Github issue https://github.com/cython/cython/issues/6599)

* A compiler hang introduced in 3.1a1 when overriding methods was resolved.
  Patch by Aditya Pillai.  (Github issue https://github.com/cython/cython/issues/6704)

* A compiler crash was resolved when trying to issue a warning.
  Patch by Gabriele N. Tornetta.  (Github issue https://github.com/cython/cython/issues/6711)

* Some incomplete import time "safety checks" from 3.1.0a1 were removed again.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6726)

3.1.0 alpha 1 (2024-11-08):

* 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 https://github.com/cython/cython/issues/6366)

* Dataclasses did not handle default fields without init value correctly.
  (Github issue https://github.com/cython/cython/issues/5858)

* Implementing a special method based on another could lead to infinite recursion.
  (Github issue https://github.com/cython/cython/issues/5863)

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

* Lambda functions had no code objects. Their signature can now be introspected.
  (Github issue https://github.com/cython/cython/issues/2983)

* Subtyping `complex` as extension type could fail.
  (Github issue https://github.com/cython/cython/issues/6346)

* ``hasattr()`` now propagates exceptions that occur during lookup.
  (Github issue https://github.com/cython/cython/issues/6269)

* The base type of extension heap types is now traversed during GC runs in Py3.9+.
  (Github issue https://github.com/cython/cython/issues/4193)

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

* Exception values were not always recognised as equal at compile time.
  (Github issue https://github.com/cython/cython/issues/5709)

* Running Cython in different Python versions could generate slightly different C code
  due to differences in the builtins.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6355)

* File paths in the C code are now relative to the build directory.
  Patch by Oscar Benjamin.  (Github issue https://github.com/cython/cython/issues/6341)

* depfiles now use relative paths whenever possible.
  Patch by Loïc Estève.  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/5760)

* Uselessly referring to C enums (not enum values) as Python objects is now rejected.
  Patch by Vyas Ramasubramani.  (Github issue https://github.com/cython/cython/issues/5638)

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

* Several C++ warnings about ``char*`` casts were resolved.
  (Github issues https://github.com/cython/cython/issues/5515, https://github.com/cython/cython/issues/5847)

* C++ undefined behaviour was fixed in an error handling case.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/5953)

* A crash was fixed when assigning a zero-length slice to a memoryview.
  Patch by Michael Man.  (Github issue https://github.com/cython/cython/issues/6227)

* Conditionally assigning to variables with the walrus operator could crash.
  (Github issue https://github.com/cython/cython/issues/6094)

* Unterminated string literals could lock up the build in an infinite loop.
  (Github issue https://github.com/cython/cython/issues/5977)

* Exporting C functions uses better platform compatible code.
  (Github issue https://github.com/cython/cython/issues/4683)

* The shebang in ``libpython.py`` was incorrect.
  Patch by Luke Hamburg.  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6354)

3.0.12 (2025-02-11):

* Release 3.0.11 introduced some incorrect ``noexcept`` warnings.
  (Github issue https://github.com/cython/cython/issues/6335)

* Conditional assignments to variables using the walrus operator could crash.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6328)

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

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

* Modules could fail to compile in PyPy 3.11 due to missing CPython specific header files.
  Patch by Matti Picus.  (Github issue https://github.com/cython/cython/issues/6482)

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

3.0.11 (2024-08-05):

* The exception check value of functions declared in pxd files was not always applied in 3.0.10.
  (Github issue https://github.com/cython/cython/issues/6122)

* A crash on exception deallocations was fixed.
  (Github issue https://github.com/cython/cython/issues/6022)

* A crash was fixed when assigning a zero-length slice to a memoryview.
  Patch by Michael Man.  (Github issue https://github.com/cython/cython/issues/6227)

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

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

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

* Fused ctuples crashed Cython.
  (Github issue https://github.com/cython/cython/issues/6068)

* A compiler crash was fixed when using extension types in fused types.
  (Github issue https://github.com/cython/cython/issues/6204)

* The module cleanup code was incorrect for globally defined memory view slices.
  (Github issue https://github.com/cython/cython/issues/6276)

* Some adaptations were made to enable compilation in Python 3.13.
  (Github issues https://github.com/cython/cython/issues/5997, https://github.com/cython/cython/issues/6182, https://github.com/cython/cython/issues/6251)

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

3.1.0 rc 1 (2025-05-01):

* 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(TheUserEnumClass.__members__)``.
  Anonymous enums still produce global item names, as before.
  (Github issue https://github.com/cython/cython/issues/4571)

3.1.0 beta 1 (2025-04-03):

* All Cython-internal types (functions, coroutines, …) are now heap types and use type specs.
  (Github issue https://github.com/cython/cython/issues/6633)

* Tracing/monitoring is now disabled in parallel/prange sections.
  (Github issue https://github.com/cython/cython/issues/6709)

* The ``numpy.math`` cimport module has been deprecated.
  Usages should be replaced by ``libc.math``.
  (Github issue https://github.com/cython/cython/issues/6743)

* Includes all fixes as of Cython 3.0.12.

3.1.0 alpha 1 (2024-11-08):

* Support for Python 2.7 - 3.7 was removed, along with large chunks of legacy code.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/5827)

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

* Docstrings now strip their leading whitespace according to PEP-257.
  Patch by Lawrence Mitchell.  (Github issue https://github.com/cython/cython/issues/6241)

* Type checkers should have it easier to find and validate Cython types in .py files.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/5842)

* Usages of the outdated ``WITH_THREAD`` macro guard were removed.
  (Github issue https://github.com/cython/cython/issues/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 https://github.com/cython/cython/issues/6036)

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