CHANGES.rst



Cython Changelog

0.29.20 (2020-0?-??)
Bugs fixed

Now uses Py_SET_SIZE() and Py_SET_REFCNT() in Py3.9+ to avoid low-level
write access to these object fields.
Patch by Victor Stinner.  (Github issue #3639)
The built-in abs() function could lead to undefined behaviour when used on
the negative-most value of a signed C integer type.
Patch by Serge Guelton.  (Github issue #1911)
Usages of sizeof() and typeid() on uninitialised variables no longer
produce a warning.
Patch by Celelibi.  (Github issue #3575)
The C++ typeid() function was allowed in C mode.
Patch by Celelibi.  (Github issue #3637)
The new c_api_binop_methods directive was added for forward compatibility, but can
only be set to True (the current default value).  It can be disabled in Cython 3.0.


0.29.19 (2020-05-20)
Bugs fixed

A typo in Windows specific code in 0.29.18 was fixed that broke "libc.math".
(Github issue #3622)
A platform specific test failure in 0.29.18 was fixed.
Patch by smutch.  (Github issue #3620)


0.29.18 (2020-05-18)
Bugs fixed

Exception position reporting could run into race conditions on threaded code.
It now uses function-local variables again.
Error handling early in the module init code could lead to a crash.
Error handling in cython.array creation was improved to avoid calling
C-API functions with an error held.
A memory corruption was fixed when garbage collection was triggered during calls
to PyType_Ready() of extension type subclasses.
(Github issue #3603)
Memory view slicing generated unused error handling code which could negatively
impact the C compiler optimisations for parallel OpenMP code etc.  Also, it is
now helped by static branch hints.
(Github issue #2987)
Cython's built-in OpenMP functions were not translated inside of call arguments.
Original patch by Celelibi and David Woods.  (Github issue #3594)
Complex buffer item types of structs of arrays could fail to validate.
Patch by Leo and smutch.  (Github issue #1407)
Decorators were not allowed on nested async def functions.
(Github issue #1462)
C-tuples could use invalid C struct casting.
Patch by MegaIng.  (Github issue #3038)
Optimised %d string formatting into f-strings failed on float values.
(Github issue #3092)
Optimised aligned string formatting (%05s, %-5s) failed.
(Github issue #3476)
When importing the old Cython build_ext integration with distutils, the
additional command line arguments leaked into the regular command.
Patch by Kamekameha.  (Github issue #2209)
When using the CYTHON_NO_PYINIT_EXPORT option in C++, the module init function
was not declared as extern "C".
(Github issue #3414)
Three missing timedelta access macros were added in cpython.datetime.
The signature of the NumPy C-API function PyArray_SearchSorted() was fixed.
Patch by Brock Mendel.  (Github issue #3606)


0.29.17 (2020-04-26)

Features added


std::move() is now available from libcpp.utility.
Patch by Omer Ozarslan.  (Github issue #2169)
The @cython.binding decorator is available in Python code.
(Github issue #3505)


Bugs fixed

Creating an empty unicode slice with large bounds could crash.
Patch by Sam Sneddon.  (Github issue #3531)
Decoding an empty bytes/char* slice with large bounds could crash.
Patch by Sam Sneddon.  (Github issue #3534)
Re-importing a Cython extension no longer raises the error
"__reduce_cython__ not found".
(Github issue #3545)
Unused C-tuples could generate incorrect code in 0.29.16.
Patch by Kirk Meyer.  (Github issue #3543)
Creating a fused function attached it to the garbage collector before it
was fully initialised, thus risking crashes in rare failure cases.
Original patch by achernomorov.  (Github issue #3215)
Temporary buffer indexing variables were not released and could show up in
C compiler warnings, e.g. in generators.
Patch by David Woods.  (Github issues #3430, #3522)
The compilation cache in cython.inline("…") failed to take the language
level into account.
Patch by will-ca.  (Github issue #3419)
The deprecated PyUnicode_GET_SIZE() function is no longer used in Py3.


0.29.16 (2020-03-24)
Bugs fixed

Temporary internal variables in nested prange loops could leak into other
threads.  Patch by Frank Schlimbach.  (Github issue #3348)
Default arguments on fused functions could crash.
Patch by David Woods.  (Github issue #3370)
C-tuples declared in .pxd files could generate incomplete C code.
Patch by Kirk Meyer.  (Github issue #1427)
Fused functions were not always detected and optimised as Cython
implemented functions.
Patch by David Woods.  (Github issue #3384)
Valid Python object concatenation of (iterable) strings to non-strings
could fail with an exception.
Patch by David Woods.  (Github issue #3433)
Using C functions as temporary values lead to invalid C code.
Original patch by David Woods.  (Github issue #3418)
Fix an unhandled C++ exception in comparisons.
Patch by David Woods.  (Github issue #3361)
Fix deprecated import of "imp" module.
Patch by Matti Picus.  (Github issue #3350)
Fix compatibility with Pythran 0.9.6 and later.
Patch by Serge Guelton.  (Github issue #3308)
The _Py_PyAtExit() function in cpython.pylifecycle was misdeclared.
Patch by Zackery Spytz.  (Github issue #3382)
Several missing declarations in cpython.* were added.
Patches by Zackery Spytz.  (Github issue #3452, #3421, #3411, #3402)
A declaration for libc.math.fpclassify() was added.
Patch by Zackery Spytz.  (Github issue #2514)
Avoid "undeclared" warning about automatically generated pickle methods.
Patch by David Woods.  (Github issue #3353)
Avoid C compiler warning about unreachable code in prange().
Some C compiler warnings in PyPy were resolved.
Patch by Matti Picus.  (Github issue #3437)


0.29.15 (2020-02-06)
Bugs fixed

Crash when returning a temporary Python object from an async-def function.
(Github issue #3337)
Crash when using **kwargs in generators.
Patch by David Woods.  (Github issue #3265)
Double reference free in __class__ cell handling for super() calls.
(Github issue #3246)
Compile error when using *args as Python class bases.
(Github issue #3338)
Import failure in IPython 7.11.
(Github issue #3297)
Fixed C name collision in the auto-pickle code.
Patch by ThePrez.  (Github issue #3238)
Deprecated import failed in Python 3.9.
(Github issue #3266)


0.29.14 (2019-11-01)

Bugs fixed

The generated code failed to initialise the tp_print slot in CPython 3.8.
Patches by Pablo Galindo and Orivej Desh.  (Github issues #3171, #3201)

? for bool was missing from the supported NumPy dtypes.
Patch by Max Klein.  (Github issue #2675)

await was not allowed inside of f-strings.
Patch by Dmitro Getz.  (Github issue #2877)
Coverage analysis failed for projects where the code resides in separate
source sub-directories.
Patch by Antonio Valentino.  (Github issue #1985)
An incorrect compiler warning was fixed in automatic C++ string conversions.
Patch by Gerion Entrup.  (Github issue #3108)
Error reports in the Jupyter notebook showed unhelpful stack traces.
Patch by Matthew Edwards (Github issue #3196).

Python.h is now also included explicitly from public header files.
(Github issue #3133).
Distutils builds with --parallel did not work when using Cython's
deprecated build_ext command.
Patch by Alphadelta14 (Github issue #3187).


Other changes

The PyMemoryView_*() C-API is available in cpython.memoryview.
Patch by Nathan Manville.  (Github issue #2541)


0.29.13 (2019-07-26)

Bugs fixed

A reference leak for None was fixed when converting a memoryview
to a Python object.  (Github issue #3023)
The declaration of PyGILState_STATE in cpython.pystate was unusable.
Patch by Kirill Smelkov.  (Github issue #2997)


Other changes

The declarations in posix.mman were extended.
Patches by Kirill Smelkov.  (Github issues #2893, #2894, #3012)


0.29.12 (2019-07-07)
Bugs fixed

Fix compile error in CPython 3.8b2 regarding the PyCode_New() signature.
(Github issue #3031)
Fix a C compiler warning about a missing int downcast.
(Github issue #3028)
Fix reported error positions of undefined builtins and constants.
Patch by Orivej Desh.  (Github issue #3030)
A 32 bit issue in the Pythran support was resolved.
Patch by Serge Guelton.  (Github issue #3032)


0.29.11 (2019-06-30)
Bugs fixed

Fix compile error in CPython 3.8b2 regarding the PyCode_New() signature.
Patch by Nick Coghlan. (Github issue #3009)
Invalid C code generated for lambda functions in cdef methods.
Patch by Josh Tobin.  (Github issue #2967)
Support slice handling in newer Pythran versions.
Patch by Serge Guelton.  (Github issue #2989)
A reference leak in power-of-2 calculation was fixed.
Patch by Sebastian Berg.  (Github issue #3022)
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.
Original patch by Matti Picus.  (Github issue #2905)
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)


0.29.10 (2019-06-02)
Bugs fixed

Fix compile errors in CPython 3.8b1 due to the new "tp_vectorcall" slots.
(Github issue #2976)


0.29.9 (2019-05-29)
Bugs fixed

Fix a crash regression in 0.29.8 when creating code objects fails.
Remove an incorrect cast when using true-division in C++ operations.
(Github issue #1950)


0.29.8 (2019-05-28)
Bugs fixed

C compile errors with CPython 3.8 were resolved.
Patch by Marcel Plch.  (Github issue #2938)
Python tuple constants that compare equal but have different item
types could incorrectly be merged into a single constant.
(Github issue #2919)
Non-ASCII characters in unprefixed strings could crash the compiler when
used with language level 3str.
Starred expressions in %-formatting tuples could fail to compile for
unicode strings.  (Github issue #2939)
Passing Python class references through cython.inline() was broken.
(Github issue #2936)


0.29.7 (2019-04-14)
Bugs fixed

Crash when the shared Cython config module gets unloaded and another Cython
module reports an exceptions.  Cython now makes sure it keeps an owned reference
to the module.
(Github issue #2885)
Resolved a C89 compilation problem when enabling the fast-gil sharing feature.
Coverage reporting did not include the signature line of cdef functions.
(Github issue #1461)
Casting a GIL-requiring function into a nogil function now issues a warning.
(Github issue #2879)
Generators and coroutines were missing their return type annotation.
(Github issue #2884)


0.29.6 (2019-02-27)
Bugs fixed

Fix a crash when accessing the __kwdefaults__ special attribute of
fused functions.  (Github issue #1470)
Fix the parsing of buffer format strings that contain numeric sizes, which
could lead to incorrect input rejections.  (Github issue #2845)
Avoid a C #pragma in old gcc versions that was only added in GCC 4.6.
Patch by Michael Anselmi.  (Github issue #2838)
Auto-encoding of Unicode strings to UTF-8 C/C++ strings failed in Python 3,
even though the default encoding there is UTF-8.
(Github issue #2819)


0.29.5 (2019-02-09)
Bugs fixed

Crash when defining a Python subclass of an extension type and repeatedly calling
a cpdef method on it.  (Github issue #2823)
Compiler crash when prange() loops appear inside of with-statements.
(Github issue #2780)
Some C compiler warnings were resolved.
Patches by Christoph Gohlke.  (Github issues #2815, #2816, #2817, #2822)
Python conversion of C++ enums failed in 0.29.
Patch by Orivej Desh.  (Github issue #2767)


0.29.4 (2019-02-01)
Bugs fixed

Division of numeric constants by a runtime value of 0 could fail to raise a
ZeroDivisionError.  (Github issue #2820)


0.29.3 (2019-01-19)
Bugs fixed

Some C code for memoryviews was generated in a non-deterministic order.
Patch by Martijn van Steenbergen.  (Github issue #2779)
C89 compatibility was accidentally lost since 0.28.
Patches by gastineau and true-pasky.  (Github issues #2778, #2801)
A C compiler cast warning was resolved.
Patch by Michael Buesch.  (Github issue #2774)
An compilation failure with complex numbers under MSVC++ was resolved.
(Github issue #2797)
Coverage reporting could fail when modules were moved around after the build.
Patch by Wenjun Si.  (Github issue #2776)


0.29.2 (2018-12-14)
Bugs fixed

The code generated for deduplicated constants leaked some references.
(Github issue #2750)
The declaration of sigismember() in libc.signal was corrected.
(Github issue #2756)
Crashes in compiler and test runner were fixed.
(Github issue #2736, #2755)
A C compiler warning about an invalid safety check was resolved.
(Github issue #2731)


0.29.1 (2018-11-24)
Bugs fixed

Extensions compiled with MinGW-64 under Windows could misinterpret integer
objects larger than 15 bit and return incorrect results.
(Github issue #2670)
Cython no longer requires the source to be writable when copying its data
into a memory view slice.
Patch by Andrey Paramonov.  (Github issue #2644)
Line tracing of try-statements generated invalid C code.
(Github issue #2274)
When using the warn.undeclared directive, Cython's own code generated
warnings that are now fixed.
Patch by Nicolas Pauss.  (Github issue #2685)
Cython's memoryviews no longer require strides for setting the shape field
but only the PyBUF_ND flag to be set.
Patch by John Kirkham.  (Github issue #2716)
Some C compiler warnings about unused memoryview code were fixed.
Patch by Ho Cheuk Ting.  (Github issue #2588)
A C compiler warning about implicit signed/unsigned conversion was fixed.
(Github issue #2729)
Assignments to C++ references returned by operator[] could fail to compile.
(Github issue #2671)
The power operator and the support for NumPy math functions were fixed
in Pythran expressions.
Patch by Serge Guelton.  (Github issues #2702, #2709)
Signatures with memory view arguments now show the expected type
when embedded in docstrings.
Patch by Matthew Chan and Benjamin Weigel.  (Github issue #2634)
Some from ... cimport ... constructs were not correctly considered
when searching modified dependencies in cythonize() to decide
whether to recompile a module.
Patch by Kryštof Pilnáček.  (Github issue #2638)
A struct field type in the cpython.array declarations was corrected.
Patch by John Kirkham.  (Github issue #2712)


0.29 (2018-10-14)

Features added

PEP-489 multi-phase module initialisation has been enabled again.  Module
reloads in other subinterpreters raise an exception to prevent corruption
of the static module state.
A set of mypy compatible PEP-484 declarations were added for Cython's C data
types to integrate with static analysers in typed Python code.  They are available
in the Cython/Shadow.pyi module and describe the types in the special cython
module that can be used for typing in Python code.
Original patch by Julian Gethmann. (Github issue #1965)
Memoryviews are supported in PEP-484/526 style type declarations.
(Github issue #2529)

@cython.nogil is supported as a C-function decorator in Python code.
(Github issue #2557)
Raising exceptions from nogil code will automatically acquire the GIL, instead
of requiring an explicit with gil block.
C++ functions can now be declared as potentially raising both C++ and Python
exceptions, so that Cython can handle both correctly.
(Github issue #2615)

cython.inline() supports a direct language_level keyword argument that
was previously only available via a directive.
A new language level name 3str was added that mostly corresponds to language
level 3, but keeps unprefixed string literals as type 'str' in both Py2 and Py3,
and the builtin 'str' type unchanged.  This will become the default in the next
Cython release and is meant to help user code a) transition more easily to this
new default and b) migrate to Python 3 source code semantics without making support
for Python 2.x difficult.
In CPython 3.6 and later, looking up globals in the module dict is almost
as fast as looking up C globals.
(Github issue #2313)
For a Python subclass of an extension type, repeated method calls to non-overridden
cpdef methods can avoid the attribute lookup in Py3.6+, which makes them 4x faster.
(Github issue #2313)
(In-)equality comparisons of objects to integer literals are faster.
(Github issue #2188)
Some internal and 1-argument method calls are faster.
Modules that cimport many external extension types from other Cython modules
execute less import requests during module initialisation.
Constant tuples and slices are deduplicated and only created once per module.
(Github issue #2292)
The coverage plugin considers more C file extensions such as .cc and .cxx.
(Github issue #2266)
The cythonize command accepts compile time variable values (as set by DEF)
through the new -E option.
Patch by Jerome Kieffer.  (Github issue #2315)

pyximport can import from namespace packages.
Patch by Prakhar Goel.  (Github issue #2294)
Some missing numpy and CPython C-API declarations were added.
Patch by John Kirkham. (Github issues #2523, #2520, #2537)
Declarations for the pylifecycle C-API functions were added in a new .pxd file
cpython.pylifecycle.
The Pythran support was updated to work with the latest Pythran 0.8.7.
Original patch by Adrien Guinet.  (Github issue #2600)

%a is included in the string formatting types that are optimised into f-strings.
In this case, it is also automatically mapped to %r in Python 2.x.
New C macro CYTHON_HEX_VERSION to access Cython's version in the same style as
PY_VERSION_HEX.
Constants in libc.math are now declared as const to simplify their handling.
An additional check_size clause was added to the ctypedef class name
specification to allow suppressing warnings when importing modules with
backwards-compatible PyTypeObject size changes.
Patch by Matti Picus.  (Github issue #2627)


Bugs fixed

The exception handling in generators and coroutines under CPython 3.7 was adapted
to the newly introduced exception stack.  Users of Cython 0.28 who want to support
Python 3.7 are encouraged to upgrade to 0.29 to avoid potentially incorrect error
reporting and tracebacks.  (Github issue #1958)
Crash when importing a module under Stackless Python that was built for CPython.
Patch by Anselm Kruis.  (Github issue #2534)
2-value slicing of typed sequences failed if the start or stop index was None.
Patch by Christian Gibson.  (Github issue #2508)
Multiplied string literals lost their factor when they are part of another
constant expression (e.g. 'x' * 10 + 'y' => 'xy').
String formatting with the '%' operator didn't call the special __rmod__()
method if the right side is a string subclass that implements it.
(Python issue 28598)
The directive language_level=3 did not apply to the first token in the
source file.  (Github issue #2230)
Overriding cpdef methods did not work in Python subclasses with slots.
Note that this can have a performance impact on calls from Cython code.
(Github issue #1771)
Fix declarations of builtin or C types using strings in pure python mode.
(Github issue #2046)
Generator expressions and lambdas failed to compile in @cfunc functions.
(Github issue #459)
Global names with const types were not excluded from star-import assignments
which could lead to invalid C code.
(Github issue #2621)
Several internal function signatures were fixed that lead to warnings in gcc-8.
(Github issue #2363)
The numpy helper functions set_array_base() and get_array_base()
were adapted to the current numpy C-API recommendations.
Patch by Matti Picus. (Github issue #2528)
Some NumPy related code was updated to avoid deprecated API usage.
Original patch by jbrockmendel.  (Github issue #2559)
Several C++ STL declarations were extended and corrected.
Patch by Valentin Valls. (Github issue #2207)
C lines of the module init function were unconditionally not reported in
exception stack traces.
Patch by Jeroen Demeyer.  (Github issue #2492)
When PEP-489 support is enabled, reloading the module overwrote any static
module state. It now raises an exception instead, given that reloading is
not actually supported.
Object-returning, C++ exception throwing functions were not checking that
the return value was non-null.
Original patch by Matt Wozniski (Github Issue #2603)
The source file encoding detection could get confused if the
c_string_encoding directive appeared within the first two lines.
(Github issue #2632)
Cython generated modules no longer emit a warning during import when the
size of the NumPy array type is larger than what was found at compile time.
Instead, this is assumed to be a backwards compatible change on NumPy side.


Other changes

Cython now emits a warning when no language_level (2, 3 or '3str') is set
explicitly, neither as a cythonize() option nor as a compiler directive.
This is meant to prepare the transition of the default language level from
currently Py2 to Py3, since that is what most new users will expect these days.
The future default will, however, not enforce unicode literals, because this
has proven a major obstacle in the support for both Python 2.x and 3.x.  The
next major release is intended to make this change, so that it will parse all
code that does not request a specific language level as Python 3 code, but with
str literals.  The language level 2 will continue to be supported for an
indefinite time.
The documentation was restructured, cleaned up and examples are now tested.
The NumPy tutorial was also rewritten to simplify the running example.
Contributed by Gabriel de Marmiesse.  (Github issue #2245)
Cython compiles less of its own modules at build time to reduce the installed
package size to about half of its previous size.  This makes the compiler
slightly slower, by about 5-7%.


0.28.6 (2018-11-01)
Bugs fixed

Extensions compiled with MinGW-64 under Windows could misinterpret integer
objects larger than 15 bit and return incorrect results.
(Github issue #2670)
Multiplied string literals lost their factor when they are part of another
constant expression (e.g. 'x' * 10 + 'y' => 'xy').


0.28.5 (2018-08-03)
Bugs fixed

The discouraged usage of GCC's attribute optimize("Os") was replaced by the
similar attribute cold to reduce the code impact of the module init functions.
(Github issue #2494)
A reference leak in Py2.x was fixed when comparing str to unicode for equality.


0.28.4 (2018-07-08)
Bugs fixed

Reallowing tp_clear() in a subtype of an @no_gc_clear extension type
generated an invalid C function call to the (non-existent) base type implementation.
(Github issue #2309)
Exception catching based on a non-literal (runtime) tuple could fail to match the
exception.  (Github issue #2425)
Compile fix for CPython 3.7.0a2.  (Github issue #2477)


0.28.3 (2018-05-27)
Bugs fixed

Set iteration was broken in non-CPython since 0.28.

UnicodeEncodeError in Py2 when %s formatting is optimised for
unicode strings.  (Github issue #2276)
Work around a crash bug in g++ 4.4.x by disabling the size reduction setting
of the module init function in this version.  (Github issue #2235)
Crash when exceptions occur early during module initialisation.
(Github issue #2199)


0.28.2 (2018-04-13)

Features added


abs() is faster for Python long objects.
The C++11 methods front() and end() were added to the declaration of
libcpp.string.  Patch by Alex Huszagh.  (Github issue #2123)
The C++11 methods reserve() and bucket_count() are declared for
libcpp.unordered_map.  Patch by Valentin Valls.  (Github issue #2168)


Bugs fixed

The copy of a read-only memoryview was considered read-only as well, whereas
a common reason to copy a read-only view is to make it writable.  The result
of the copying is now a writable buffer by default.
(Github issue #2134)
The switch statement generation failed to apply recursively to the body of
converted if-statements.

NULL was sometimes rejected as exception return value when the returned
type is a fused pointer type.
Patch by Callie LeFave.  (Github issue #2177)
Fixed compatibility with PyPy 5.11.
Patch by Matti Picus.  (Github issue #2165)


Other changes