gssapi fails to import: ./Include/cpython/tupleobject.h:23: PyTuple_GET_SIZE: Assertion `PyTuple_Check(op)' failed. about python-gssapi

[mgorny]

Filed cython/cython#5665.

[mgorny]

Hmm, it seems to be related to building with Cython 3. If I force Cython < 3 in pyproject.toml), it doesn't assert.

[jborean93]

Thanks for confirming the Cython 3 behaviour I was just about to ask. I might just need to keep the pin at < 3 for now and push a new release.

[mgorny]

Hmm, this may actually be a bug in Cython. FWICS it's caused by RequirementFlag using a metaclass. Even if I replace the metaclass with plain EnumMeta, it still crashes. I'm going to try to build a standalone reproducer.

[mgorny]

Yep, I've got a trivial reproducer. Lemme retry with cython main and then file a bug there.

[jborean93]

#328 puts back the upper bound for Cython in the build deps as well as adds a basic check in CI to hopefully catch this issue in the future if it happens again.