Level 1 is the most basic minimal regex support for Unicode. http://unicode.org/reports/tr18/
As far as I know, Dmitry Olhansky is actively working on Level 1 conformance as part of his GSoC project.
Indeed, and it's already here, though with a couple of quirks. To the best of my knowledge my project addresses all of the present issues with std.regex. Which reminds me that it should go a little more public soon, stay tuned.
That's great to hear! It's a little embarassing that we don't have this already.
Does the new regex package now close this bug?
Closing this as full level 1 support is provided. Any problems and/or missing functionality should be regarded as bugs and filed as such.