Sourced from cython's changelog.

3.3.1 (2026-11-01)

Most of the bugs fixed in this release were regressions in 3.3.0.

Features added

• Declarations for the C99 bool type in <stdbool.h> were added. (Github issue :issue:8011)

• Fused function objects are slightly smaller in the Limited API. (Github issue :issue:7967)

• Cython warns when enabling subinterpreter support for modules that cannot currently support it for technical reasons. (Github issue :issue:8006)

• The shared module is now automatically declared as freethreading_compatible and sets subinterpretes_compatible as applicable (currently depending on memoryview usage). Both are overridable by users as usual. (Github issue :issue:8037)

Bugs fixed

• Constant folding of multiplied sequences could return incorrect results. Patch by orztrickster. (Github issue :issue:8021)

• Cython 3.3.0 incorrectly assumed that Python integer powers always return integers. Patch by Clay Dugo. (Github issue :issue:7989)

• The return value of optimised calls to dict.get(), dict.pop() and dict.setdefault() were inferred independent of their default values, leading to incorrect C code being generated. (Github issue :issue:7991)

• Some redeclarations of annotated variables were incorrectly rejected. They are now generally allowed and Cython only warns about obviously incorrect cases. (Github issue :issue:7920)

• Type inference now respects annotation_typing=False for local variable annotations. Patch by GruffElixir. (Github issue :issue:7994)

• Type inference depended on arbitrary set ordering when circular references are involved. As an effect, the Cython.Compiler.FlowControl module was translated to slightly non-deterministic C code. (Github issue :issue:8002)

• Assigning different slices of the same memoryview to different extension type attributes could generate incorrect refcounting code.

... (truncated)

• 59e1b91 Fix several CyCache cleanup issues. (GH-8090)
• f3690a3 Update changelog.
• 86d6869 Update changelog.
• 92ca11d Update changelog.
• 9b2d20b Update documentation and test for passing "--module-name" to "cython generate...
• f7fea5a Shared module: ensure build directory path is stripped from source filename a...
• 6827d3a Update changelog.
• bb7c995 Prepare release of 3.3.1.
• 68ba6a6 Avoid unused is_unsigned warning when converting large enums (#8087)
• 1be89f9 Manual dependency update for cibuildwheel (#8074)
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