`rustc` package is currently only available on `amd64` in Prebuilt-MPR

[hwittenborn]

I'm writing this as a notice for anyone experiencing this issue:

The rustc package is currently only available on the amd64 architecture in the Prebuilt-MPR, even though it's a source package and should be buildable on other architectures like arm64.

This limitation is due to the Prebuilt-MPR utilizing virtualization to build for architectures other than amd64, and this limitation causes rustc builds to time out during builds.

There hasn't been any fix for this yet, but if you need the latest version of Rust from the Prebuilt-MPR it's recommended that you install rustup instead, which will work as a drop-in replacement for rust (after running rustup update stable on all users).