I kinda disagree. With C, you risk old autoconf scripts breaking, depending on library versions that operating systems don't include anymore, compilers learning

I kinda disagree. With C, you risk old autoconf scripts breaking, depending on library versions that operating systems don't include anymore, compilers learning how to exploit undefined behaviour they didn't exploit before, programs breaking due to making incorrect assumptions (`char` is signed, right?). C++ also adds exciting issues in terms of backwards compatibility breaks (for instance, programs using `register` keyword won't work since C++14) - refer to Annex C in C++ specification for a long list of BC breaks. None of this is an issue in Rust. Cargo is a proper build system, not a weird combination of shell script and M4 using programs that are prone to breaking changes (like awk). Cargo requires defining program dependencies and prevents accidentally using a dependency that exists on an operating system. Rust in safe code avoids undefined behaviour, noticeably avoiding the risk of accidental undefined behaviour. Rust has much less implementation-defined behaviour than C (`i8` is a well defined type). Rust edition system means that breaking changes avoid affecting old code (even if Rust were to, say, remove `static mut` in edition 2024, this change wouldn't affect programs that wouldn't explicitly upgrade to edition 2014). Rust is serious about backwards compatibility. Breaking changes are mostly unacceptable (other than in cases of soundness bugs, but even then there is typically a warning cycle before fixing a bug). In fact, you may take a look at "Compatibility notes" sections in https://github.com/rust-lang/rust/blob/master/RELEASES.md https://github.com/rust-lang/rust/blob/master/RELEASES.md. The compatibility breaks tend to be very minor, and unlikely to break stuff. For instance, in Rust 1.39, `asinh(-0.0)` was changed to return `-0.0` instead of `0.0`. Strictly speaking a breaking change, but a program depending on that is very very unlikely. Rust also has crater which prevents accidentally breaking backwards compatibility by testing whether every public GitHub repository and crates.io library still works the same way. Additionally, even in case program compilation breaks anyway, it's possible to use an older version of a compiler with rustup. Rust is here to stay. Even if Mozilla ended up supporting the project, some other company that uses Rust internally would continue to support it. It's free software after all. Even if that wouldn't happen, the old rustc releases would still work.