Rust

Changing a Rust enum variant through a mutable reference can be achieved either by wrapping the variant attached variable inside Option, or better, by introducing an Undef variant in the enum.

Although ArrayQueue contains no explicit spin lock or mutex, its code structure forms a big spin lock and thus deadlock is possible.

Calling a Rust closure from assembly code involves erasing the type and converting everything into raw pointers before passing to the assembly code, and then reconstructing Rust objects from the raw pointers once control returns to Rust.