...as revised by P1289R1.
(I'm creating PRs for new features so there's some way of tracking whether someone's working on them)
I saw this through reddit:
https://gitlab.com/lock3/gcc-new.git branch origin/contracts-jac-kona
This user has several interesting branches of contracts and concepts!
The Wiki I noted was a 3rd party one.
This is the wiki connected to the repo: