Issues

• [BUG] except* in async def, generators, at module level or in module-level class bodies generates C that doesn't compile (__pyx_skip_add_traceback undeclared)

  cython/cython#8043 · Filter by author bwenstar opened on Oct 12, 2026

• [BUG] Frame leak, or "f->f_back == NULL" assertion in __Pyx_Coroutine_SendEx, when an awaited Python coroutine re-raises the exception being handled

  cython/cython#8042 · Filter by author bwenstar opened on Oct 12, 2026

• [BUG] Generator module fails to compile with -DCYTHON_TRACE=1 on 3.13+ when linetrace directive is off: __Pyx_MonitoringEventTypes_CyGen_count undeclared

  cython/cython#8040 · Filter by author pattems opened on Oct 11, 2026
  1

• [BUG] Explicit base class call of a cpdef method emits no call event when profile=True

  cython/cython#8034 · Filter by author fangchenli opened on Oct 6, 2026

• [BUG] When Cython uses sys.monitoring, profilers installed with sys.setprofile get useless duplicate calls

  cython/cython#8032 · Filter by author godlygeek opened on Oct 4, 2026
  5

• [BUG] Segfault when throwing into a pending async generator aclose() that suspends again

  cython/cython#8027 · Filter by author Crypt0-M3lon opened on Oct 2, 2026

• [BUG] using cpdef-ed methods as list items results in segfaults

  cython/cython#8001 · Filter by author TTsangSC opened on Sep 20, 2026
  2

• [ENH] Introduce support of vectors

  feature
  cython/cython#8000 · Filter by author matusvalo opened on Sep 19, 2026
  1

• [BUG] cython 3.3.0 randomly fails in parallel builds

  cython/cython#7997 · Filter by author rossburton opened on Sep 14, 2026
  28

• [BUG] 3.3.0 regression: dict[str, str].get(missing_key) is typed as str, so the returned None takes str fast paths (bool/len/in give wrong results)

  defectType Analysis
  cython/cython#7991 · Filter by author ChCh27 opened on Sep 13, 2026 · 3.3.1
  4

• [BUG] Compiler-cache cleanup deletes active temporary files from concurrent Cython processes

  cython/cython#7983 · Filter by author vyasr opened on Sep 10, 2026
  1

• Use continuous benchmarking

  Testing
  cython/cython#7981 · Filter by author scoder opened on Sep 10, 2026

• [BUG] __Pyx_PyIndex_AsSsize_t ~9% slower per conversion in 3.3.0 (lost compact-int fast path)

  cython/cython#7979 · Filter by author juenglin opened on Sep 9, 2026
  4

• Read pyproject.toml for default configuration

  Build Systemfeature
  cython/cython#7978 · Filter by author scoder opened on Sep 9, 2026
  2

• Remove duplicated options test if Options.annotate or options.annotate and friends

  cleanup
  cython/cython#7963 · Filter by author matusvalo opened on Sep 3, 2026

• [BUG] -Wunused-result warnings in generated code

  cython/cython#7934 · Filter by author Flamefire opened on Aug 26, 2026
  1

• Pure Python mode: len(obj) assignment without annotations automatically becomes Py_ssize_t

  cython/cython#7933 · Filter by author dg-pb opened on Aug 25, 2026
  8

• Don't fail with mismatched Cython ABI module types

  cython/cython#7929 · Filter by author da-woods opened on Aug 25, 2026

• [BUG] C++: assigning a conditional expression into a container element generates a dangling __Pyx_FakeReference temporary

  cython/cython#7927 · Filter by author krishyshah opened on Aug 24, 2026

• [BUG] abi3t / freethreading-limited-api-preview: CYTHON_USE_MODULE_STATE=1 together with Py_TARGET_ABI3T fails

  Code Generationdefect
  cython/cython#7905 · Filter by author paultiq opened on Aug 20, 2026
  4

• Optimise plain Python object creation in CPython

  cython/cython#7886 · Filter by author scoder opened on Aug 5, 2026
  1

• Refactor call nodes

  cleanup
  cython/cython#7885 · Filter by author scoder opened on Aug 4, 2026

• [ENH] Infer the result type of python functions

  enhancementType Analysis
  cython/cython#7882 · Filter by author matusvalo opened on Aug 1, 2026
  5

• [BUG] Shared utility module fails in coverage analysis

  Build Systemdefect
  cython/cython#7872 · Filter by author scoder opened on Jul 30, 2026
  2

• [ENH] cpython.weakref: Add PyWeakref_IsDead (and backport to Python < 3.14)

  enhancementLibrary
  cython/cython#7869 · Filter by author mkoeppe opened on Jul 30, 2026
  1