Red Hat Enterprise Linux is a very influential yet deliberately conservative distro. They will be packaging Firefox 59 ESR when it releases in March 2018. Firefox 59 moves from nightly to beta on January 15, 2018, at which time the stable release of Rust will be 1.23 (having released nine days earlier, on January 4). Therefore, to build Firefox, RHEL will package Rust 1.23. Though there do exist other ways to obtain Rust on RHEL, it seems safe to assume that this will be the one and only version of Rust that RHEL will ship by default until 2019.
If we expect Rust to make traction in enterprise environments, we should assume that 1.23 is the version that they will target. This essentially turns 1.23 into a quasi-LTS whether we like it or not, and we might want to consider ensuring that “official” libraries don’t use any features that will keep them from compiling on 1.23.
But the most immediate concern is that Rust 1.23 is currently in nightly, and will move to beta on November 23. This is our last chance to have any say over the platform that prospective enterprise users will want to use, at least until 2019. Are there any features on the horizon that we really, really want to prioritize for this development cycle?