> Do you validate every single unsafe code in every single library you use? Even the standard library? Every time? We don't need to? Rust's main soundness theo

> Do you validate every single unsafe code in every single library you use? Even the standard library? Every time? We don't need to? Rust's main soundness theorem says that if a safe Rust API is sound, then safe Rust code using it is sound. So the only thing we need to check is that the unsafe code that _we_ write is sound, and we 100% do this all the way for the standard library. In the standard library _every_ unsafe block has a comment explaining why the "user-provided soundness proof" that they represent is correct. We even have a linter that actually rejects PRs that add unsafe blocks to the standard library without such comments. > Do you validate every single unsafe code in every single library you use? Even the standard library? Every time? Soundness is IMO Rust's main feature and its main core value, and is more important than other Rust core values like, e.g., zero-overhead abstractions, which are also extremely important. Soundness is what enables "Hack without fear", "no segfaults", "refactor without fear", cargo ("large scale software without fear"), crates.io ("using other people's libraries without fear")... and it's what sets Rust apart from unsound-by-design languages like D, Nim, Zig, C, C++, etc. I haven't read the book in a long time, but the documentation I do read (nomicon, spec, unsafe code guidelines, issue tracker, internals) makes it very clear that making sure that unsafe Rust code is correct is critical for the ecosystem and for users to benefit from the main advantages Rust has to offer.