Wuffs is a language by Google that allows safe parsing without runtime bound checks, by forcing the coder to prove an array access is within bounds before acessing.
Rust's runtime bound checker is enough for 99% of applications, but there's a niche for languages like Wuff which is when bound checks hurt performance for ultra critical fast parsing like a server parsing millions of images.
Couldn't Rust implement something like this? When disabling bound checking, instead of doing an unsafe operation, we should prove that we can disable it. Just as lifetimes prove to the compiler that it's safe to accept a reference for some period of time.
This would make Rust even safer as some people might try to do these performance critical things in unsafe code and mess things. Also, interfacing Wuffs with Rust is unsafe. Imagine if we had safe unbound-checked arrays in Rust (for these specific cases).