Damn, damn, damn. I checked out the latest MLton with the `fix' and although
it solves the problem for the reduced version of the failure, the original
code, compiled with
-g -native false -keep g -keep ssa -keep dot
-DGC_EVERY_CHECK -DINSTRUMENTED
seg-faults. No assertion failure, just a simple seg-fault.
If I add
-limit-check-per-block false
still causes the same death.
I am open to things to try.