Aliasing is checked in the calling code, not the callee. You’re not allow to create a mutable reference if another exists in the same scope. If you use “plain”

Aliasing is checked in the calling code, not the callee. You’re not allow to create a mutable reference if another exists in the same scope. If you use “plain” safe Rust, there’s simply just no way to create alias mutable references unsafely. (The C default you refer to is at the compiler internals level. The Rust alias prevention we’re talking about is at the language level. C compilers will try to avoid generating code that will behave incorrectly in the presence of aliasing, but do nothing to prevent aliasing and the possible logic and thread safety issues caused by aliasing. Rust makes almost all of these cases disappear for the programmer.)