Basically, no, it won't. Rust still reserves some rights to break the existing code if the found issue is considered to be "severe" (e.g. type system soundness

Basically, no, it won't. Rust still reserves some rights to break the existing code if the found issue is considered to be "severe" (e.g. type system soundness issues), but those cases should be extremely low. In most cases workarounds will be introduced rather than breaking changes. More details at https://github.com/rust-lang/rfcs/blob/master/text/1122-language-semver.md https://github.com/rust-lang/rfcs/blob/master/text/1122-lang... Also note that the Rust team tests all the crates before making a (minor) breaking change to see the impact of the breakage to the ecosystem. (possibly "popular crates only", when the ecosystem grows huge in the future)