Depending on the level of maturity of the nightly features you rely on, for CI there is an env variable that makes the stable compiler think it is nightly. We u

Depending on the level of maturity of the nightly features you rely on, for CI there is an env variable that makes the stable compiler think it is nightly. We use this flag at day job to use latest stable but be able to enable a handful of quasi stable nightly features (custom testing frameworks mainly and getting rocket to play nice). This is a double edged sword: it is the same as a pinned nightly in the sense that it is a static target, but differs in that bugs affecting stable and beta have been backported where any arbitrary nightly has no assurances one way or another, but bugs affecting nightly features aren't backported to the stable release and only fixed on nightly. Also, for the love all that is holy do not publish a crate relying on that flag to enable the nightly features, it breaks the languages stability assurances and by extension the ecosystem.