A release on crates.io with stable support?

[tanriol]

Would be nice to have a version on crates.io that supports stable Rust.

[Lolirofle]

I had a "stable" Cargo feature, but I was not sure whether it worked because I never tested it. Did you test it and did it work? I made it the default behaviour in the last commit, but I still have not pushed it to crates.io because I am unsure of whether it is working or not.

[tanriol]

As of 439ccf5, I've compiled my project with it, derived EnumDiscriminant and it seemed to work (although not tested much).