Update dependency Cython to ~=3.3.0 - #34

v3.3.0

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==================

(Complete changelog for the 3.3.0 release, including pre-releases.)

Features added

• PEP-634 Pattern Matching is implemented.
  (Github issue :issue:4029)

• except * (PEP-654 exception groups) is implemented for Python 3.11 and later.
  (Github issue :issue:4993)

• Unpacking in comprehensions (PEP-798) is implemented for list/set/dict comprehensions.
  It is not yet available for generator expressions.
  Original patch by Morax. (Github issue :issue:7898)

• Changes were made to adapt to Python 3.15 and its Limited API.
  This does not yet cover abi3t.
  (Github issues :issue:6405, :issue:7190, :issue:7347, :issue:7348, :issue:7358)

• Cython now uses a new export/import naming scheme for fused C functions that
  increases the resilience against seemingly compatible user code changes.
  The original names are kept for backwards compatibility.
  (Github issue :issue:7656)

• Declared container item types (e.g. list[float] or tuple[atype, ...])
  are now used by the type system.
  (Github issues :issue:7288, :issue:7798)

• Type inference was improved for builtin Python types and their methods.
  (Github issues :issue:7536, :issue:7644, :issue:7887, :issue:7888)

• Exception base types are inferred for the target variable of multi-exception except
  clauses and for collections of exceptions. Properties like .args and .context
  use direct C access in CPython.
  (Github issue :issue:7783)

• Annotations on global variables are now used by type inference.
  (Github issue :issue:7877)

• The feature set of the shared module can be selected at build time
  by listing named features to include or exclude.
  This is an experimental configuration, subject to further improvements.
  Failures to include used features will currently result in import failures.
  (Github issue :issue:7759)

• To control the generation of the shared module, the cython command gained
  a sub-command cython generate-shared pkg/modulename.c with additional options
  --only and --exclude.
  Patch by Raza Khan. (Github issue :issue:7842)

• Conditions in strongly predictable if-clauses or if-else expressions can be wrapped in
  cython.likely(condition) or cython.unlikely(condition) to help the C compiler
  optimise the branch. Note that Cython automatically detects raise and assert
  statements as terminators already and marks if-clauses that directly lead to them as
  unlikely(), without user interaction.
  (Github issue :issue:7667)

• Extension types can declare themselves explicitly as sequence or mapping with
  @cython.collection_type("sequence") or @cython.collection_type("mapping").
  This has an effect on their behaviour in pattern matching and subscripting.
  (Github issue :issue:5027)

• Sequence types marked as @cython.collection_type("sequence") that use C integers
  in the subscript special methods now implement only the sequence and not the mapping protocol.
  This allows subscripting code to avoid creating Python index objects when the index
  is already available as C integer.
  (Github issue :issue:7435)

• Sequence types that have their Py_TPFLAGS_SEQUENCE type flag set can benefit from
  faster subscripting via the sequence protocol as Cython now bypasses the mapping protocol
  for them if both protocols are implemented.
  (Github issue :issue:7432)

• The Py3.15 frozendict builtin type is supported and has been backported as an alias
  for dict in older Python versions.
  Patches to adapt existing dict optimisations were contributed by Omkar Kabde.
  (Github issues :issue:7545, :issue:7647)

• The Py3.15 sentinel builtin is supported and its C-API declarations are available in
  cpython.sentinel.

• cython.py_int (and the same for py_float, py_complex and py_bool)
  can be used to refer to Python's builtin types in a C type context, e.g. after cdef,
  where they are normally shadowed by the C types of the same name.
  (Github issue :issue:7844)

• The builtin Python types int, float, str, bytes and bytearray
  are special cased in comparisons to speed them up.
  (Github issues :issue:7452, :issue:7474)

• The builtin Python types int and float are special cased in +, - and *
  operations with (compile-time) unknown Python types in order to speed them up.
  The bit operations ^, | and & are additionally special cased for int.
  (Github issues :issue:7485, :issue:7541)

• <bool> casts can be used to convert C values to Python True / False.
  (Github issue :issue:7513)

• cdef property methods support setters.
  (Github issues :issue:7505, :issue:7791)

• The C restrict modifier can be used in declarations.
  (Github issue :issue:7617)

• C arrays may now be declared with (extern or internal) enum values as their size.
  (Github issues :issue:7401, :issue:7406)

• prange(num_threads=0) automatically selects the maximum number of OpenMP threads.
  (Github issue :issue:7586)

• prange() and parallel() sections can be used without releasing the GIL, which
  helps in freethreading builds. When releasing the GIL as part of the section declaration,
  re-acquiring it immediately inside is now faster, e.g. to do per-thread Python initialisations.
  (Github issue :issue:6562)

• cython.pymutex and cython.pythread_type_lock now support a .locked() method
  to check if the lock is currently held without blocking. The method works on all Python
  versions using atomic reads on Python 3.13+ and a try-acquire approach on older versions.
  (Github issue :issue:7275)

• A simpler mechanism was added for implementing C++ exception handlers in Cython code.
  (Github issues :issue:7388, :issue:7390)

• Repeated memoryview slicing inside of loops now avoids redundant reference counting,
  making it substantially faster.
  (Github issue :issue:5507)

• Indexing into Cython memoryview objects from Python is faster.
  (Github issue :issue:7529)

• Some internal call overhead in the memoryview code was removed.
  (Github issue :issue:7609)

• Extension types use the vectorcall interface for their instantiation in many cases.
  This can be configured with a new C feature macro CYTHON_VECTORCALL_TPNEW.
  (Github issue :issue:7698)

• Coroutine methods use the faster vectorcall interface.
  (Github issue :issue:7678)

• Vectorcalls with literal keyword arguments use cached constant keyword name tuples.
  (Github issue :issue:7713)

• List comprehensions that generate new objects avoid refcounting overhead for appending.
  (Github issue :issue:7748)

• Method calls in older Limited API versions are slightly faster.
  (Github issue :issue:7707)

• Constant frozenset objects are deduplicated and cached at module init time
  (similar to constant tuple and slice objects).
  Original Patch by Zhenbo Li. (Github issue :issue:2741)

• C arrays are substituted for sequence iteration in more cases, also inside of generators.
  Ad-hoc C array storage on the stack and in closures was reworked along the way.
  (Github issues :issue:7323, :issue:7339)

• Single character in-tests on str, bytes and bytearray are optimised.
  (Github issue :issue:3888)

• Unicode string comparisons to single character literals are faster.
  (Github issue :issue:7418)

• F-strings are a little faster in some cases.
  (Github issues :issue:7495, :issue:7526)

• Formatting C floating point values in f-strings avoids creating Python floats in some cases.
  Patch by Vladimir Saraikin. (Github issue :issue:7797)

• bytearray.extend(bytes) is faster.
  (Github issue :issue:7797)

• assert conditions are constant-folded.
  (Github issue :issue:7809)

• PyPy and GraalPython use the vectorcall protocol to enable faster Python calls in future releases.
  (Github issue :issue:7614)

• The runtime conversion from a Python mapping to a C struct/union uses less code.
  (Github issue :issue:7343)

• The error handling of memoryviews uses less code.
  (Github issue :issue:7525)

• The runtime dispatch code of fused types uses less code.
  (Github issue :issue:7501)

• More code is extracted to the shared utility code module.
  (Github issues :issue:7556, :issue:7570)

• Async generator objects are slightly smaller.
  (Github issue :issue:7776)

• Cython compiled functions have a more efficient memory layout in the Limited API.
  (Github issue :issue:7519)

• Module string content is now compressed with LZSS by default, which reduces the footprint of the
  decompressor code compared to the 3.2.x default zlib. This also avoids a runtime dependency
  on the zlib module since the tiny LZSS decompressor can be embedded in the module.
  (Github issue :issue:7577)

• The Py2 print statement is now implemented in Cython instead of C to make it
  thread-safe and uses a vectorcall into Python.
  (Github issue :issue:7642)

• Several C++ exception declarations were added to libcpp.exceptions.
  (Github issue :issue:7389)

• Missing Python type flag declarations were added to cpython.object.
  (Github issue :issue:7441)

• Declarations for PyType_GetSlot() and the corresponding type slot IDs were added
  to cpython.type.

• Declarations for specialised byte-conversion functions were added to cpython.long and cpython.float.
  Patch by Valentin Valls. (Github issue :issue:7738)

• Error detection when assigning to const variables was improved.
  (Github issue :issue:7359)

• Some cases of likely misuse of critical_section now generate warnings.
  (Github issue :issue:6766)

• Programmatic use of Cython has become easier by avoiding the need to manually set up
  the error reporting.
  (Github issue :issue:7235)

• Autoscaling in cymeit is a little faster.

• TreeFragment.parse_from_strings() now supports full modules and .pxd files.
  Patch by Itamar Turner-Trauring. (Github issue :issue:7827)

• Unicode 17.0.0 is used to parse identifiers.

Bugs fixed

• Several issues with .close() or .throw() of Async generator asend/athrow
  objects were resolved, following fixes in CPython.
  (Github issue :issue:7777)

• The __class__ method cell misbehaved when used together with class decorators
  and passed the decorated class (and thus an arbitrary object) into super()
  instead of the class object.
  (Github issue :issue:7721)

• A return value from within a prange() loop could silently return the
  default value of the return type instead of the user provided value.
  (Github issue :issue:7587)

• Assigning a Python 3.14+ .__annotate__ function to a Cython compiled function no
  longer evaluates annotations eagerly.
  (Github issue :issue:7767)

• Generated Cython language features like properties, auto-pickle or dataclasses
  now use a critical section (on the object itself) as guard for concurrent access.
  (Github issue :issue:6621)

• The star-import implementation needlessly rejected several names in internal use.
  They are now allowed and become regular Python module attributes.
  (Github issue :issue:4931)

• Mixing function signature declarations in Python modules and their .pxd modules could fail.
  (Github issues :issue:5970, :issue:4388)

• C array declarations with type and size could fail with an exception in pure Python code.
  (Github issue :issue:7372)

• A const modifier in C++ template type arguments could be mapped incorrectly.
  (Github issue :issue:6294)

• C++ typeid() failed to compile on more complex expressions.
  (Github issue :issue:7069)

• Optimised Python int and float operations did not remember their result type,
  leading to less optimised code in longer expressions.
  (Github issues :issue:7363, :issue:7502)

• Slices as dictionary keys confused the type inference of item access.
  (Github issue :issue:7702)

• A race condition when returning from a cython.parallel.parallel section was fixed.
  (Github issue :issue:6521)

• Cython still used (type, exc, traceback) for saving and restoring exception state,
  even though modern CPython versions only store the exception object itself internally.
  This is now modernised in many places to reduce overhead.
  (Github issue :issue:7481)

• Exceptions originating from the Py_UNICODE_IS*() character classification macros and
  the corresponding str.is*() methods, which they alias, were not handled but ignored in
  the Limited API.
  (Github issue :issue:7602)

• In the Limited API, import time failures to create code objects for compiled functions,
  e.g. due to future Python API changes, are no longer fatal but generate a warning.
  (Github issue :issue:5718)

• Several internal cases where exceptions are caught and discarded now propagate the
  BaseException errors and only discard the expected exceptions.
  (Github issue :issue:7600)

• Error handling was improved when setting up the table of cdef methods for extension types
  and unexpected errors are propagated.
  (Github issue :issue:7613)

• Exceptions while setting up the automatic pickle support are now propagated.
  (Github issue :issue:7613)

• Exceptions thrown into async generators could leave the generator in an unclosed state.
  (Github issue :issue:7618)

• In the Limited API, failures while formatting type names in exceptions are now uniformly handled.
  (Github issue :issue:7680)

• A cpdef enum with negative values changed to non-negative in Python 3.15.
  It now uses a dedicated enum implementation class to allow this.
  (Github issue :issue:7185)

• cpdef fused functions generated redundant code.
  (Github issue :issue:7778)

• Automatic C++ STL conversions in different compiler directive contexts could generate
  invalid code duplications in C++ code.
  Original Patch by bjodah. (Github issue :issue:6981)

• The global module state struct now lives in an anonymous namespace in C++ mode to
  allow linking multiple modules together in one shared library file.
  (Github issue :issue:7159)

• Cached methods of builtin types were not GC-traversed and cleaned up as part of the module state.
  Patch by Maxwell Bernstein. (Github issue :issue:7468)

• Dict iteration generates safer code in PyPy/GraalPy/free-threading.
  (Github issue :issue:7637)

• The floating point parsing code relied on C implementation specific "pointer compare after free" behaviour.
  Patch by stratakis. (Github issue :issue:7463)

• When non-heap types were used as base classes of extension heap types, the heap types
  were not correctly reference counted by their instances.
  (Github issue :issue:7483)

• The .__signatures__ dict of fused functions is no longer writable.
  (Github issue :issue:7386)

• A minimal implementation of .__annotate__ was added to Cython compiled functions to make
  @functools.wraps work in Python 3.14+.
  (Github issue :issue:7675)

• The --embed-positions option no longer includes absolute file paths in the C code.
  (Github issue :issue:6755)

• Casting to an unresolved typeof() type (e.g. cython.cast(cython.typeof(x), ...)
  where the type could not be inferred) crashed the compiler instead of reporting an error.
  Patch by Vladimir Saraikin. (Github issue :issue:7683)

• Error reporting on missing braces in f-strings was misleading.
  (Github issue :issue:7436)

• Declaring a __dict__ attribute in a class as public or readonly
  generated incorrect code. It is now detected as an error.
  Patch by Anthony Donlon. (Github issue :issue:7823)

• None default values for function arguments declared as not None are now rejected
  at compile time rather than leading to errors at runtime.
  Patch by Vyas Ramasubramani. (Github issue :issue:7762)

• Cython did not reject code with multiple contradicting type annotations on the same variable.
  (Github issue :issue:7246)

• Cython no longer warns if @profile or @linetrace is applied to a function
  without changing the global/outer setting. This avoids annoyance when users leave
  such redundant decorators in the code for occasional use.

• The virtualenv activation inside of cygdb when it is run from a virtualenv works in more cases.
  Original patch by Pierrick Koch and Ashutosh Varma. (Github issues :issue:1961, :issue:3629)

• Modules with non-ASCII names could end up with UTF-8 characters in their C code.
  (Github issue :issue:7588)

• MSVC could silently truncate long C string literals (including internal ones)
  at a 64k bytes border. This is now worked around using C char arrays.
  (Github issue :issue:7824)

• Several C compiler warnings related to mixed signed/unsigned C integer usage were resolved.

• Some compiler directives failed to apply to Cython's build, which lead to
  unintentionally (slightly) increased wheel sizes.
  (Github issue :issue:7801)

• A regression in 3.3.0b1 that generated invalid C code for exception type checks was fixed.
  (Github issue :issue:7902)

• Includes all fixes as of Cython 3.2.9.

Other changes

• Support for Python 3.8 has been removed.
  As a side-effekt, support for StacklessPython and Pyston (last release was 3.8) was also removed.
  Python 3.9 is planned to remain supported for several years due to its use in LTS Linux distributions.
  (Github issue :issue:7271)

• The vectorcall feature macros were unified to make CYTHON_VECTORCALL the only way to
  disable this feature (if need arises). Previously the option macros CYTHON_METH_FASTCALL,
  CYTHON_FAST_PYCALL and CYTHON_VECTORCALL all controlled different aspects of the
  implementation.
  (Github issue :issue:7616)

• Setting the Limited API version macro Py_LIMITED_API in PyPy or GraalPython
  now enables the Limited API usage in these runtimes. This will currently fail
  due to lack of support in the runtimes, but is intended for initial testing
  and future improvements.
  (Github issue :issue:7831)

• Setting Py_LIMITED_API to a newer API version x.y than the current runtime
  (and its header files) is now detected and will explicitly fail to compile,
  rather than running into less obvious C compile or runtime issues.
  (Github issue :issue:7185)

• Coroutines no longer provide the legacy _is_coroutine property.
  (Github issue :issue:7709)

• Two more Cython modules are compiled in the binary wheels, which should improve the
  translation speed for modules with many strings.
  (Github issue :issue:7795)

• The distributed Cython binary wheels now use a shared utility code module to reduce their size.
  (Github issue :issue:7865)

• Cython/Shadow.pyi has been merged into Cython/Shadow.py.
  (Github issue :issue:7376)

• The documentation now uses the "Clarity" Sphinx theme.
  Patch by Libor Jelínek. (Github issue :issue:7564)

v3.2.9

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==================

Bugs fixed

• Indexing into freshly created lists with an out-of-bounds index could crash.
  (Github issue :issue:7793)

• Function arguments with default values could end up uninitialised in closures, leading to crashes.
  Patch by Anthony Donlon. (Github issue :issue:7782)

• bytearray.append(None) could crash. The optimised code was also lacking concurrency guards.
  (Github issue :issue:7796)

• Some rare corner cases when concatenating text strings were resolved.
  (Github issue :issue:7799)

• Assignments of builtin string types to typedefs of object could erroneously be rejected.
  (Github issue :issue:7789)

• Subscripting type failed with a TypeError.
  (Github issue :issue:5563)

• Manually disabling CYTHON_VECTORCALL in CPython could lead to invalid C code.
  Patch by Florent Gallaire. (Github issue :issue:7807)

• Some internal Limited API version checks for Py3.12 were corrected.
  (Github issue :issue:7845)

v3.2.8

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Bugs fixed

• Assigning a Python 3.14+ .__annotate__ function to a Cython compiled function no longer
  evaluates annotations eagerly. Fixes a regression with @functools.wraps() in Cython 3.2.6.
  Patch by Jelle Zijlstra. (Github issue :issue:7767)

• In freethreading Python, the necessary object keep-alive while executing user code in
  .__dealloc__() uses a safer scheme.
  Patch by Yaxing Cai. (Github issue :issue:7769)

• The local function state used by sys.monitoring read from uninitialised memory.
  (Github issue :issue:7774)

• The .ag_running flag attribute of async generators was always false on big-endian systems.

v3.2.6

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==================

Bugs fixed

• @functools.wraps() was broken in Py3.14+ for Cython compiled functions.
  (Github issue :issue:7675)

• A double-free in the t-string code was fixed.
  (Github issue :issue:7712)

• The - operator declarations for iterators in libcpp.vector we corrected.
  Patch by Vadim Markovtsev. (Github issue :issue:7717)

• The shared utility code module no longer uses a temporary file path that
  changed the C code on each generation.
  (Github issue :issue:7723)

• On 32 bit platforms, cached constants are no longer made immortal during module import.
  (Github issue :issue:7744)

Other changes

• Binary wheels are now built with -DNDEBUG to discard runtime assertions from CPython's
  inline functions.

v3.2.5

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Bugs fixed

• A compile failure was fixed when using the walrus operator inside of try-except.
  (Github issue :issue:7462)

• Expressions with side-effects as object argument to isinstance() could get
  evaluated multiple times, e.g. when they use the walrus operator.
  (Github issue :issue:7670)

• Several problems generating the shared utility module were resolved, including
  a performance regression with memory views.
  (Github issues :issue:7487, :issue:7497, :issue:7504, :issue:7558)

• Some GC and refcounting issues were resolved for Cython functions in the Limited API.
  (Github issue :issue:7594)

• Refcounting errors and error handling issues were resolved in some rare error handling cases.
  (Github issues :issue:7597, :issue:7599, :issue:7612, :issue:7673)

• Using cython.pymutex in an extension type with cdef methods generated
  invalid C code missing the required PyMutex declarations.
  (Github issue :issue:6995)

• Calling .get_frame() on Cython coroutines could crash in freethreading Python.
  (Github issue :issue:7632)

• The vectorcall protocol was not used correctly in .throw() of Cython coroutines
  when raising the exception only by type (without value or traceback).
  (Github issue :issue:7677)

• A problem with cpdef enums in the Limited API of Python 3.11+ was resolved.
  (Github issue :issue:7503)

• Unicode predicates like .isdigit() are now allowed to fail in the Limited API.
  (Github issue :issue:7602)

• Conditional expressions mixing Python float and int object types could accidentally
  infer float as the common result type, instead of treating both independently.

• Using sizeof() in the size declarations of extern arrays failed.
  (Github issue :issue:7451)

• Enabling profiling generated invalid C code for non-Python return tuples.
  (Github issue :issue:7580)

• abs() on C long long values could generate invalid C code.

• When the CYTHON_AVOID_BORROWED_REFS C macro is enabled, e.g. in GraalPython,
  dict iteration could fail to compile.
  Patch by Michael Šimáček. (Github issue :issue:7631)

• A C compiler warning about unused functions was resolved.
  (Github issue :issue:7560)

• The py_safe_call_once() C++ mutex helper function in libcpp.mutex
  failed to compile.
  (Github issue :issue:7585)

• The cpython.array declarations were adapted for Python 3.15. Direct access
  to the C struct of the array.array data type might require user code changes.
  (Github issue :issue:7659)

• Spaces in file paths written to the depfile were not escaped.
  Patch by Loïc Estève. (Github issue :issue:7423)

• Cython's cache failed to restore multi-file results.
  (Github issue :issue:7559)

• Using Tempita from its command line failed with a name error.
  (Github issue :issue:7567)

Other changes

• The known builtin types were updated for Py3.15.

v3.2.4

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Features added

• In preparation of Cython 3.3, a new decorator @collection_type(tname) can be used
  to advertise an extension type as being a 'sequence' or 'mapping'. This currently
  only has the effect of setting the Py_TPFLAGS_SEQUENCE flag on the type or not, but
  is provided for convenience to allow using the new decorator already in Cython 3.2 code.

• Several C++ exception declarations were added to libcpp.exceptions.
  (Github issue :issue:7389)

Bugs fixed

• Pseudo-literal default values of function arguments like arg=str() could generate
  invalid C code when internally converted into a real literal.
  (Github issue :issue:6192)

• The pickle serialisation of extension types using the auto_pickle feature was
  larger than necessary since 3.2.0 for types without Python object attributes.
  It is now back to the state before 3.2.0 again.
  (Github issue :issue:7443)

• Constants are now only made immortal on freethreading Python if they are not shared.
  (Github issue :issue:7439)

• PyDict_SetDefaultRef() is now used when available to avoid temporary borrowed references.
  (Github issue :issue:7347)

• Includes all fixes as of Cython 3.1.8.

v3.2.3

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Features added

• The C-API declarations were updated to include the new PyList_*() functions.
  (Github issue :issue:7291)

• The Py_mod_gil module setting can now be changed with a C macro, overriding
  the freethreading_compatible directive setting.
  (Github issue :issue:7404)

Bugs fixed

• t-strings lost the last element when compiled for the Limited API.
  (Github issue :issue:7381)

• The array.data property of the cpython.array declarations generated a
  useless exception check that degraded its use in nogil code.
  (Github issue :issue:7408)

• Parallel builds with the cythonize command could request more processes
  than allowed by the platform, thus failing the build.
  (Github issue :issue:7384)

• A minor thread sanitizer issue was resolved.
  (Github issue :issue:7383)

v3.2.2

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Features added

• The C-API declarations were updated to include the new PyDict_*Ref() functions.
  (Github issue :issue:7291)

Bugs fixed

• Iteration over literal sequences and strings in generators generated invalid C code since 3.2.0.
  This was a regression due to the C array iteration optimisation in :issue:6926, which is now
  disabled inside of generators.
  (Github issue :issue:7342)

• Calling special methods of known exception types failed with an AttributeError.
  (Github issue :issue:7342)

• Calling the unbound __mul__ special method of builtin collections with subtypes failed.
  (Github issue :issue:7340)

• C string literals could generate invalid "const to non-const" casts in the C code.
  (Github issue :issue:7346)

• yield is no longer allowed inside of a cython.critical_section,
  but is now allowed while holding a cython.pymutex.
  (Github issue :issue:7317)

• Under lock congestion, acquiring the GIL could crash in Python 3.11, part 2.
  This bug was introduced in Cython 3.2.0.
  (Github issue :issue:7312)

• The new py_safe_* functions in libc.threads triggered C compiler warnings.
  (Github issue :issue:7356)

v3.2.1

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Features added

• Cython now leaves markers about its utility code dependencies in the generated C code
  to help debugging "unused function" C compiler warnings.
  (Github issue :issue:7294)

Bugs fixed

• Relative imports could fail if the shared utility module is used.
  This bug was introduced in Cython 3.2.0.
  (Github issue :issue:7290)

• Under lock congestion, acquiring the GIL could crash in Python 3.11.
  This bug was introduced in Cython 3.2.0.
  (Github issue :issue:7312)

• Using the shared utility module left an unused C function in user modules with memoryviews.
  To make debugging this kind of issue easier, Cython now leaves "used by …" markers in the
  generated C files that indicate why a specific piece of utility code was included.
  This bug was introduced in Cython 3.2.0.
  (Github issue :issue:7293)

• Code using the pre-import scope failed with an undefined name.
  This bug was introduced in Cython 3.2.0.
  (Github issue :issue:7304)

• Includes all fixes as of Cython 3.1.7.

v3.2.0

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==================

(Complete changelog for the 3.2.0 release, including pre-releases.)

Features added

• Builtin exception types are now inferred.
  (Github issue :issue:6908)

• The list of known, inferred and optimised Python builtins was updated.
  range is now considered a type. ascii, bin, format, hex, oct were added as functions.
  (Github issue :issue:6931)

• The f-string syntax was extended according to PEP-701.
  (Github issue :issue:5452)

• t-strings are implemented according to PEP-750. The implementation backports the template classes
  but prefers existing backports if installed separately.
  (Github issue :issue:6811)

• Unknown return type annotations with -> are no longer rejected but produce warnings.
  This allows better integration with Python type hints that are not always usable for Cython.
  -> None is also allowed now.
  Patch by jpe. (Github issue :issue:6946)

• The runtime Python dispatch for fused functions is substantially faster.
  (Github issues :issue:1385, :issue:6996)

• Freelists (via cdef class decorator and for internally used types such as async)
  are now also used in the Limited API and with extension type specs enabled.
  (Github issue :issue:7151)

• Module imports now quickly check for an already imported module to speed up reimports.
  Patch by Lysandros Nikolaou. (Github issue :issue:7035)

• Type checks on PEP-604 union types (int | None) are optimised into separate checks.
  (Github issue :issue:6935)

• Assignments to the PEP-604 union type float | None allow any suitable Python number as input
  and convert it to a Python float automatically.
  (Github issue :issue:5750)

• Item type inference was improved for looping over literals.
  (Github issue :issue:6912)

• Looping over literal sequences and strings now uses efficient C array looping if possible.
  (Github issue :issue:6926)

• Releasing the GIL from an unknown lock state is more efficient.
  (Github issue :issue:6847)

• cython.critical_section(PyMutex) now works, as with Python objects.
  (Github issue :issue:6847)

• bool(c_int/float/ptr) avoid passing through Python objects.
  (Github issue :issue:7015)

• Variables assigned inside of prange loops can now be initialised outside of the loop.
  (Github issue :issue:7178)

• Unused exceptions in except clauses are detected in some more cases to avoid their normalisation.
  (Github issue :issue:7021)

• Mixed operations on C integers with Python ints use less code and are more streamlined for Py3.12+.
  (Github issue :issue:7244)

• Some object constants are now marked as immortal to speed up their reference counting
  in recent CPython versions. This can be configured with the CYTHON_IMMORTAL_CONSTANTS C macro.
  (Github issue :issue:7118)

• Further improvements were made to reduce the size of the resulting extension modules.
  (Github issue :issue:6983, :issue:7199, :issue:7220, :issue:7238,
  :issue:7255, :issue:7265)

• Several improvements were made in freethreaded Python code.
  (Github issues :issue:6936, :issue:6939, :issue:6949, :issue:6984,
  :issue:7011, :issue:7066, :issue:7114, :issue:7200)

• Several improvements were made for the Limited API.
  (Github issues :issue:6959, :issue:6991)

• Several improvements were made for the GraalPython support.
  Patch by Michael Šimáček. (Github issue :issue:7074)

• Some GIL-safe C-API wrappers were added to the libc/libcpp declarations.
  (Github issue :issue:6829, :issue:6993)

• String and number constants use less storage space in the module.
  (Github issues :issue:6971, :issue:6978, :issue:6986)

• The managed dict/weakref support in CPython 3.12+ is used for internal types
  to benefit from future CPython optimisations here.
  (Github issue :issue:6891)

• Using NaN as exception return value is supported.
  (Github issues :issue:6900, :issue:6903)

• Declarations for C++ condition variables were added.
  (Github issue :issue:6836)

• The annotated source HTML page shows alternating +/− markers to open/close lines.
  Patch by Kamil Monicz. (Github issue :issue:7099)

• cython --embed gained a new option --embed-modules=… to list further extension modules
  that will be statically linked into the generated extension module, to get them initialised
  on application start.
  (Github issue :issue:2849)

• The setup.py script of Cython now allows passing the desired Limited API version
  like --cython-limited-api=3.11.
  (Github issue :issue:7228)

• Unicode 16.0.0 is used to parse identifiers.

Bugs fixed

• Special float exception values could generate invalid C code.
  (Github issues :issue:6900, :issue:6903)

• References to the Python bool type could generate invalid C code.
  (Github issue :issue:6902)

• Using cython.pymutex in an extension type declared as public or api
  generated invalid C code missing the required PyMutex declarations.
  (Github issues :issue:6992, :issue:6995)

• Cython's type sharing across modules suffered from race conditions if multiple modules
  tried to initialise and share their types concurrently. This is due to an underlying
  CPython issue and cannot easily be worked around completely. In the common case that
  module dicts are plain Python dict objects, however, Cython now uses a .setdefault()
  equivalent for thread-safe type sharing.
  See python/cpython#137422
  (Github issue :issue:7076)

• Cython incorrectly called PyList_GetItemRef() in PyPy and GraalPython before Py3.13.
  (Github issue :issue:7269)

• Iterating over temporary memoryviews could crash Cython.
  (Github issue :issue:7005)

• Type casts on constants as part of numeric expressions could crash Cython.
  (Github issue :issue:6779)

• Long code bodies in with statements could crash Cython.
  (Github issue :issue:7122)

• Vectorcalls could use needless temp assignments for self.
  (Github issue :issue:6909)

• Indexing bytes failed to optimise in some cases.
  (Github issue :issue:6997)

• Optimised C integer formatting in f-strings failed to apply to typedef types.
  (Github issue :issue:7170)

• In auto-pickling, trying to unpickle an object that has no __dict__ from object pickle data
  that includes instance dict state is now an error.
  (Github issue :issue:7222)

• The type objects of heap types were not always correctly decrefed on deallocation.
  (Github issue :issue:7145)

• Pure mode type aliases like p_int or ulong leaked into some C type contexts,
  risking to conflict with user declarations.
  (Github issues :issue:6922, :issue:6339)

• Boolean (emptyness) tests on builtin containers could fail to handle (unlikely) errors.
  (Github issue :issue:7090)

• The return type of bytes.join() was sometimes inferred as plain object.
  (Github issue :issue:6987)

• Type inference could fail to understand prange() arguments.
  (Github issue :issue:6974)

• embedsignatures failed if lambda was used in function default arguments.
  (Github issue :issue:6880)

• An internal C function was not marked as static and leaked a linker symbol.
  (Github issue :issue:6957)

• PyType_FromModuleAndSpec was incorrectly used in Limited API code before Py3.10.
  (Github issue :issue:7181)

• Conversion code for memoryview dtypes from and to Python objects generated C warnings about
  incorrect const / non-const casting code.
  (Github issue :issue:7219)

• Cython's tools and frontend scripts now use python3 instead of just python
  in their shebang line.
  Patch by Matti Picus. (Github issue :issue:7053)

• Extension arguments defined for the shared code module were ignored in cythonize().
  (Github issue :issue:7251)

• Failures while following package attributes in import pkg.module as … were not handled.

• Trying to instantiate internal types used by Cython is now prohibited.
  (Github issue :issue:7263)

• The setup.py script in the Demos/ subdirectory failed to build.
  (Github issue :issue:7228)

• The cygdb program failed to work with virtualenvs on Windows.
  Patch by Merlin. (Github issue :issue:7268)

• Includes all fixes as of Cython 3.1.6.

Other changes

• Some lesser used platforms (Windows ARM/i686, macOS x86_64, Linux i686, musllinux)
  now use Py3.9 abi3 binary wheels instead of Python version specific wheels.
  We also added an abi3 wheel for armv7l.
  (Github issues :issue:7227, :issue:7248, :issue:7250)

• Usages of Py_TPFLAGS_HAVE_FINALIZE were removed. The constant remains available as cimport from
  cpython.object for legacy reasons.
  (Github issue :issue:6423)

v3.1.8

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==================

Bugs fixed

• Assignment expressions used in comprehensions could look at the wrong scope,
  thus using different variables and different data.
  (Github issue :issue:6547)

• Some internal C symbols were not declared as static, preventing static linking
  of multiple modules.
  Patch by Yury Popov. (Github issue :issue:7310)

• Accidentally using except + in C mode did not raise a compile error but generated
  invalid C code leading to obscure error messages.
  Patch by user202729. (Github issue :issue:6560)

v3.1.7

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==================

Bugs fixed

• Unicode characters formatted from C integers with padding, as in f"{value:XXc}",
  could result in invalid Python string objects since Cython 3.1.0.
  Also, lone surrogates failed to format in this way.
  (Github issue :issue:7298)

• Assigning nested structs from a list of structs (item by item) could crash Cython.
  (Github issue :issue:7308)

• Cython incorrectly called PyList_GetItemRef() in PyPy and GraalPython before Py3.13.
  (Github issue :issue:7269)

• Trying to instantiate internal types used by Cython is now prohibited.
  (Github issue :issue:7263)

v3.1.6

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Bugs fixed

• Unicode characters formatted from C integers with f"{value:c}" could result in
  invalid Python string objects since Cython 3.1.0.
  (Github issue :issue:7240)

• cythonize (program and function) now uses concurrent.futures.ProcessPoolExecutor
  instead of multiprocessing.Pool to fix a hang on build failures in parallel builds.
  A possible work-around is to disable parallel builds.
  Patch by Sviatoslav Sydorenko. (Github issue :issue:7183)

v3.1.5

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Bugs fixed

• Conversion from C++ strings longer than PY_SSIZE_T_MAX did not validate the length.

• Some non-Limited API code was incorrectly used in generated header files.
  (Github issue :issue:7157)

• Optimised unpacking of Python integers in expressions uses a slightly safer scheme.
  (Github issue :issue:7134)

• Empty return statements were not always reported when tracing.
  (Github issue :issue:7022)

• Value conversion errors when tracing C return statements no longer fail the trace
  but fall back to reporting None returns instead.
  (Github issue :issue:6503)

v3.1.4

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Features added

• Declarations for the new PyUnstable_*() refcounting C-API functions in Py3.14 were added.

Bugs fixed

• The monitoring code could crash on tracing.
  (Github issue :issue:7050)

• Initialising the monitoring code could fail with a CPython exception.
  See nedbat/coveragepy#1790 (comment)

• Optimised integer shifting triggered undefined behaviour in C.
  (Github issue :issue:7089)

• Deallocating objects that inherit from external types defined in pxd files
  could run into an infinite loop.
  (Github issue :issue:7143)

• A reference to metaclasses could be leaked on instantiation.
  (Github issue :issue:7130)

• (Unlikely) error handling during empty builtin container tests was ineffective.
  (Github issue :issue:7190)

• Generated *_api.h files used potentially unknown Cython configuration macros.
  (Github issue :issue:7108)

• cythonize() avoids parallel compiler runs on systems using spawn() in multiprocessing.
  Patch by Marcel Bargull. (Github issue :issue:3262)

• The @cython.ufunc decorator was missing in type checker stubs.
  Patch by jayClean. (Github issue :issue:7109)

v3.1.3

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Bugs fixed

• Some method calls with 0 or 1 argument failed to use PyObject_VectorCallMethod().

• Walrus assignments of literal Python integers could generate invalid C code.
  (Github issue :issue:6989)

• cython.pythread_type_lock (also used as fallback for cython.pymutex)
  could stall on heavily contended locks.
  (Github issue :issue:6999)

• C string arrays (not pointers) always coerced to the Python default string type,
  even on explicit casts to other string types.
  (Github issue :issue:7020)

• Unterminated \N{} character escapes in strings could unrail the parser.
  (Github issue :issue:7056)

• An internal C function was not marked as static and leaked a linker symbol.
  (Github issue :issue:6957)

• Some Unicode letters were not recognised as lexically valid name parts.
  (Github issue :issue:7059)

• Compatibility with PyPy3.8 was lost by accident.

• The Linux binary wheels of 3.1.2 used SSSE3 CPU instructions which are not available on some CPUs.
  (Github issue :issue:7038)

v3.1.2

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Bugs fixed

• Attribute lookups failed on the bool builtin type.
  (Github issue :issue:6905)

• Type checks on or-ed union types could incorrectly return false.
  (Github issue :issue:6420)

• Negative list indexing could accidentally wrap around twice in PyPy and the Limited API.

• Iterating over literal sequences with starred (unpacked) items could infer a wrong
  type for the loop variable and fail to assign the values.
  (Github issue :issue:6924)

• Calls to C functions taking exception types failed to check for a None argument.
  (Github issue :issue:6420)

• Fused functions had an incorrect __module__ attribute.
  (Github issue :issue:6897)

• The type of Cython implemented functions had an incorrect __module__ attribute.
  (Github issue :issue:6841)

• Errors while indexing into bytearray or str in nogil sections could crash.
  (Github issue :issue:6947)

• bytearray.append() could silently accept some invalid character numbers.

• The C++11 <type_traits> header was included regardless of the C++ version.
  (Github issue :issue:6896)

• PyDict_GetItemStringRef() was accidentally used in older Limited API versions.
  (Github issue :issue:6914)

• abort() was used but not always available in the Limited API.
  (Github issue :issue:6918)

• Some dependencies were missing from the depfile.
  (Github issue :issue:6938)

• Embedded function signatures were not always separated from the existing docstring.
  (Github issue :issue:6904)

• numpy.math was missing from Cython/Includes/ and could not be cimported.
  (Github issue :issue:6859)

• Some tests were adapted for NumPy 2.x.
  (Github issue :issue:6898)

• Some C compiler warnings were fixed.
  (Github issue :issue:6870)

• Cython.Build was not officially exposing the cythonize function.
  (Github issue :issue:6934)

v3.1.1

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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)

v3.1.0

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==================

Other changes

• No functional changes since 3.1.0 rc 2.