Rust compiler support works differently

Yes, most old code will compile without issues. AFAICT, the Rust compatibility story is one of the best out there. The only specific example that comes to mind right now is Rust 1.80 vs `time`, but that one was special in that it was actually detected and disregarded. However, I do remember reading several times in Rust changelogs things like "We detected XX crates that failed to compile with this change and worked with their authors to get a new, fixed version out".