The closest I've seen is Qemu record/replay, but that's very slow (no KVM acceleration, no multicore), and broken in current Qemu versions (replayed system just gets stuck).

Can IntelliJ be configured to simply use whatever JDK belongs to the `javac` in PATH? If so, it should suffice to simply start it in a `nix-shell`. If not, maybe setting `JAVA_HOME` in your `.envrc` could help?

For most C ecosystem stuff you can try overriding the version, but you'll quickly notice why this is a hard problem: Different software versions want to be built in different ways! Someone would have to therefore maintain the quirks of each package version's build process for each package for all eternity, an insanely huge endeavor.

Also, even if it were possible this would break the Nix binary cache model, because suddenly you'd have an insane combinatorial explosion of not just package versions, but also versions of their dependencies. In order to preserve purity and reproducibility, a change in dependency version means that all dependents have to be rebuilt, taking up insane amounts of CPU and storage on the build farm.

I don't think that your request is unreasonable (I'd love to have this feature!), but it's probably not fully possible in any software distribution ecosystem.

Also, the Rust community at large is not at all enthusiastic about handing the language over to ISO. The design-by-comitee-based, incrementalist, waterfall throw-it-over-the-wall-every-3-years approach is pretty much the exact opposite of the continuous delivery-based way Rust is developed, and arguably one of the main reasons why C++ sucks.