1.9 tail-call optimization status?

vm_opts.h contains:


In an interview, ko1 mentioned it should be enabled in 1.9’s release,
and needed testing:

Gray Soft / Not Found

Current Ruby 1.9 (trunk) is not enabled this optimization. If you want
to try this, please re-write that option in “vm_opts.h”
(OPT_TAILCALL_OPTIMIZATION) and re-compile that. I think release
version of Ruby 1.9 is enabled this optimization. I need more comments
of it

That was a year ago, and I’ve not noticed much else in the way of
references to it. Is anyone aware of it’s current status? It seems to
work, but I can’t say I’ve tested it significantly.