There's no lock file in that project. But moreover, you stumbled upon one of the worst cases, a soundness problem that has yielded a lot of discussion because

There's no lock file in that project. But moreover, you stumbled upon one of the worst cases, a soundness problem that has yielded a lot of discussion because of that crate specifically: https://github.com/rust-lang/rust/issues/50781 https://github.com/rust-lang/rust/issues/50781 The issue here is that the typemap crate was found to be relying on a compiler bug. The compiler bug could be exploited to write transmute in safe code: in other words, all the safety guarantees of Rust go out the window unless we break that crate. It's a bad situation, but I don't know what we could have done differently. I think everyone agrees it's not worth sacrificing all the safety properties of Rust to keep typemap building.