I’d like to see the latest stable version of Rust.
This would allow Rust developers to use features that aren’t available on Rust playground, such as “multiplayer” development.
I wanted to use one of the latest stable Rust features - GATs (Generic Associated Types).
One solution that I find reasonable is automatic updates of rustc. I believe there’s a release schedule that you might follow. Since stabilization of Rust features has several stages (nightly → beta → stable), I don’t expect any vulnerabilities caused by it.