Giving out two mutable aliases to an integer or struct holding integers is perfectly safe in C and C++ and JS and Java and Python... and perfectly safe in Rust

Giving out two mutable aliases to an integer or struct holding integers is perfectly safe in C and C++ and JS and Java and Python... and perfectly safe in Rust if you hand out multiple &struct and mark each field as Cell<T> (just with painful syntax compared to any other imperative language in existence).