==========================
Features added
--------------
* Cython functions now use the PEP-590 vectorcall protocol in Py3.7+.
Patch by Jeroen Demeyer. (Github issue 2263)
* Unicode identifiers are supported in Cython code (PEP 3131).
Patch by David Woods. (Github issue 2601)
* Unicode module names and imports are supported.
Patch by David Woods. (Github issue 3119)
* Annotations are no longer parsed, keeping them as strings following PEP-563.
Patch by David Woods. (Github issue 3285)
* Preliminary support for the CPython's ``Py_LIMITED_API`` (stable ABI) is
available by setting the ``CYTHON_LIMITED_API`` C macro. Note that the
support is currently in an early stage and many features do not yet work.
Patches by Eddie Elizondo and David Woods. (Github issues 3223, 3311, 3501)
* The dispatch to fused functions is now linear in the number of arguments,
which makes it much faster, often 2x or more, and several times faster for
larger fused types with many specialisations.
Patch by will-ca. (Github issue 1385)
* ``with gil/nogil`` statements can be conditional based on compile-time
constants, e.g. fused type checks.
Patch by Noam Hershtig. (Github issue 2579)
* ``const`` can be used together with fused types.
Patch by Thomas Vincent. (Github issue 1772)
* Reimports of already imported modules are substantially faster.
(Github issue 2854)
* Positional-only arguments are supported in Python functions.
Patch by Josh Tobin. (Github issue 2915)
* The ``volatile`` C modifier is supported in Cython code.
Patch by Jeroen Demeyer. (Github issue 1667)
* ``cython.trashcan(True)`` can be used on an extension type to enable the
CPython trashcan. This allows deallocating deeply recursive objects without
overflowing the stack. Patch by Jeroen Demeyer. (Github issue 2842)
* Inlined properties can be defined for external extension types.
Patch by Matti Picus. (Github issue 2640)
* The ``str()`` builtin now calls ``PyObject_Str()`` instead of going
through a Python call.
Patch by William Ayd. (Github issue 3279)
* String concatenation can now happen in place if possible, by extending the
existing string rather than always creating a new one.
Patch by David Woods. (Github issue 3453)
* Multiplication of Python numbers with small constant integers is faster.
(Github issue 2808)
* Some list copying is avoided internally when a new list needs to be created
but we already have a fresh one.
(Github issue 3494)
* Extension types that do not need their own ``tp_new`` implementation (because
they have no object attributes etc.) directly inherit the implementation of
their parent type if possible.
(Github issue 1555)
* The attributes ``gen.gi_frame`` and ``coro.cr_frame`` of Cython compiled
generators and coroutines now return an actual frame object for introspection.
(Github issue 2306)
* Several declarations in ``cpython.*``, ``libc.*`` and ``libcpp.*`` were added.
Patches by Jeroen Demeyer, Matthew Edwards, Chris Gyurgyik, Jerome Kieffer
and Zackery Spytz.
(Github issues 3468, 3332, 3202, 3188, 3179, 2891, 2826, 2713)
* Deprecated NumPy API usages were removed from ``numpy.pxd``.
Patch by Matti Picus. (Github issue 3365)
* ``cython.inline()`` now sets the ``NPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION``
C macro automatically when ``numpy`` is imported in the code, to avoid C compiler
warnings about deprecated NumPy C-API usage.
* The builtin ``abs()`` function can now be used on C numbers in nogil code.
Patch by Elliott Sales de Andrade. (Github issue 2748)
* PEP-479 (``generator_stop``) is now enabled by default with language level 3.
(Github issue 2580)
* The ``cython.view.array`` type supports inheritance.
Patch by David Woods. (Github issue 3413)
* Code annotation accepts a new debugging argument ``--annotate-fullc`` that
will include the complete syntax highlighted C file in the HTML output.
(Github issue 2855)
* ``--no-capture`` added to ``runtests.py`` to prevent stdout/stderr capturing
during srctree tests.
Patch by Matti Picus. (Github issue 2701)
* ``--no-docstrings`` option added to ``cythonize`` script.
Original patch by mo-han. (Github issue 2889)
* ``cygdb`` gives better error messages when it fails to initialise the
Python runtime support in gdb.
Patch by Volker Weissmann. (Github issue 3489)
* The Pythran ``shape`` attribute is supported.
Patch by Serge Guelton. (Github issue 3307)
Bugs fixed
----------
* The unicode methods ``.upper()``, ``.lower()`` and ``.title()`` were
incorrectly optimised for single character input values and only returned
the first character if multiple characters should have been returned.
They now use the original Python methods again.
* Fused argument types were not correctly handled in type annotations and
``cython.locals()``.
Patch by David Woods. (Github issues 3391, 3142)
* Diverging from the usual behaviour, ``len(memoryview)``, ``len(char*)``
and ``len(Py_UNICODE*)`` returned an unsigned ``size_t`` value. They now
return a signed ``Py_ssize_t``, like other usages of ``len()``.
* Nested dict literals in function call kwargs could incorrectly raise an
error about duplicate keyword arguments, which are allowed when passing
them from dict literals.
(Github issue 2963)
* Item access (subscripting) with integer indices/keys always tried the
Sequence protocol before the Mapping protocol, which diverged from Python
semantics. It now passes through the Mapping protocol first when supported.
(Github issue 1807)
* Name lookups in class bodies no longer go through an attribute lookup.
Patch by Jeroen Demeyer. (Github issue 3100)
* Broadcast assignments to a multi-dimensional memory view slice could end
up in the wrong places when the underlying memory view is known to be
contiguous but the slice is not.
(Github issue 2941)
* Pickling unbound methods of Python classes failed.
Patch by Pierre Glaser. (Github issue 2972)
* The ``Py_hash_t`` type failed to accept arbitrary "index" values.
(Github issue 2752)
* The first function line number of functions with decorators pointed to the
signature line and not the first decorator line, as in Python.
Patch by Felix Kohlgrüber. (Github issue 2536)
* Constant integer expressions that used a negative exponent were evaluated
as integer 0 instead of the expected float value.
Patch by Kryštof Pilnáček. (Github issue 2133)
* The ``cython.declare()`` and ``cython.cast()`` functions could fail in pure mode.
Patch by Dmitry Shesterkin. (Github issue 3244)
* ``__doc__`` was not available inside of the class body during class creation.
(Github issue 1635)
* Setting ``language_level=2`` in a file did not work if ``language_level=3``
was enabled globally before.
Patch by Jeroen Demeyer. (Github issue 2791)
* ``__init__.pyx`` files were not always considered as package indicators.
(Github issue 2665)
* Compiling package ``__init__`` files could fail under Windows due to an
undefined export symbol. (Github issue 2968)
* A C compiler cast warning was resolved.
Patch by Michael Buesch. (Github issue 2775)
* Binding staticmethods of Cython functions were not behaving like Python methods.
Patch by Jeroen Demeyer. (Github issue 3106, 3102)
* Memoryviews failed to compile when the ``cache_builtins`` feature was disabled.
Patch by David Woods. (Github issue 3406)
Other changes
-------------
* The default language level was changed to ``3str``, i.e. Python 3 semantics,
but with ``str`` literals (also in Python 2.7). This is a backwards incompatible
change from the previous default of Python 2 semantics. The previous behaviour
is available through the directive ``language_level=2``.
(Github issue 2565)
* Cython no longer generates ``__qualname__`` attributes for classes in Python
2.x since they are problematic there and not correctly maintained for subclasses.
Patch by Jeroen Demeyer. (Github issue 2772)
* Source file fingerprinting now uses SHA-1 instead of MD5 since the latter
tends to be slower and less widely supported these days.
(Github issue 2790)
* The long deprecated include files ``python_*``, ``stdio``, ``stdlib`` and
``stl`` in ``Cython/Includes/Deprecated/`` were removed. Use the ``libc.*``
and ``cpython.*`` pxd modules instead.
Patch by Jeroen Demeyer. (Github issue 2904)
* The search order for include files was changed. Previously it was
``include_directories``, ``Cython/Includes``, ``sys.path``. Now it is
``include_directories``, ``sys.path``, ``Cython/Includes``. This was done to
allow third-party ``*.pxd`` files to override the ones in Cython.
Patch by Matti Picus. (Github issue 2905)
* The command line parser was rewritten and modernised using ``argparse``.
Patch by Egor Dranischnikow. (Github issue 2952, 3001)
* Dotted filenames for qualified module names (``pkg.mod.pyx``) are deprecated.
Use the normal Python package directory layout instead.
(Github issue 2686)
* Binary Linux wheels now follow the manylinux2010 standard.
Patch by Alexey Stepanov. (Github issue 3355)
* Support for Python 2.6 was removed.