Unsafe Rust is an esoteric language without iron-clad guarantees, and type-level programming and async Rust is an esoteric metalanguage (https://hirrolot.github

Unsafe Rust is an esoteric language without iron-clad guarantees, and type-level programming and async Rust is an esoteric metalanguage (https://hirrolot.github.io/posts/rust-is-hard-or-the-misery-of-mainstream-programming.html https://hirrolot.github.io/posts/rust-is-hard-or-the-misery-...). For example, matklad made a recent blog post on "Caches In Rust" (https://matklad.github.io/2022/06/11/caches-in-rust.html https://matklad.github.io/2022/06/11/caches-in-rust.html). The cache is built around https://docs.rs/elsa https://docs.rs/elsa, which is built around https://docs.rs/stable_deref_trait/latest/stable_deref_trait/trait.StableDeref.html https://docs.rs/stable_deref_trait/latest/stable_deref_trait..., which is unsound for Box and violates stacked borrows in its current form: https://github.com/Storyyeller/stable_deref_trait/issues/15 https://github.com/Storyyeller/stable_deref_trait/issues/15 There is a recurring trend of sound C programs turning into unsound Rust programs, because shared mutability is often necessary but it's difficult to avoid creating &mut, and Stacked Borrows places strict conditions on constructing &mut T (they invalidate some but not all aliasing *const T).