Calling this a compile error - as it seems to be compiler dependent.

In other projects - when I have experienced issues as this it has been an uninitiated variable - somewhere.

I would appreciate some suggestions on how to best debug this - as it seems to occur even before tracemalloc can be activated.

$ ./python -X tracemalloc
Objects/genobject.c:127: _PyObject_GC_TRACK: Assertion "!(((PyGC_Head *)(op)-1)->_gc_next != 0)" failed: object already tracked by the garbage collector
Enable tracemalloc to get the memory block allocation traceback

object address  : 30085150
object refcount : 0
object type     : 20013ea0
object type name: generator
object repr     : <refcnt 0 at 30085150>

Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: core initialized

Current thread 0x00000001 (most recent call first):
  File "<frozen importlib._bootstrap_external>", line 1593 in _setup
  File "<frozen importlib._bootstrap_external>", line 1634 in _install
  File "<frozen importlib._bootstrap>", line 1189 in _install_external_importers
IOT/Abort trap(coredump)

p.s. I can always build using a different compiler and try to get it to report on this object using the values listed above - and/or insert more debug code.

Next step I'll try is using dbx (AIX debugger) for a stacktrace.

Thanks!