Yep. At my employer, all programs that get deployed to production must be built with either the current version of the toolchain, or the previous version. All b

Yep. At my employer, all programs that get deployed to production must be built with either the current version of the toolchain, or the previous version. All builds are hermetic, and it's a requirement that all programs get rebuilt and redeployed at least once every N months, so that the programs out in the wild aren't built with toolchains and libraries that are too wildly different from head. But there's a whole team dedicated to the task of maintaining that state here. I can imagine that at a company where this is not the core competency, there would be some slippage.