The documentation for PyType_Spec and the related functions is not clear about the required lifetime of fields of PyType_Spec. 

In particular, PyType_Spec.name must remain valid for the entire lifetime of types created with PyType_FromSpec*.  The documentation doesn't mention this.

I ran into this with code that calculates the name as needed an cleans up the memory used for the type spec after creating the type. The type appears to work fine when looking at it in Python scripts, but the tp_name slot is wrong.