AFAICT, it is disabled by default, and it is not documented in the ASDF
So is this code even live, except for in the test scripts?
It was pretty painful to get this to work because it relies on
unexported (and hence unstable) SBCL internals.
My *guess* is that this was originally done as a way to dispense with
`WITH-COMPILATION-UNIT` and hence potentially parallelize the
If no one is even using it, I am tempted to move it to be a contrib and
drop it from the tests and maintenance as part of core ASDF. Maybe it
would be better as a part of a POIU extension to ASDF, and relieve me of
dealing with these SBCL compiler internals?