Rust: What is the difference between Deref and DerefMut?

Deref — dereference operator. DerefMut — mutable dereference.

Deref:

• Implements * operator.
• Enables deref coercion.
• For smart pointers.

DerefMut:

• Mutable dereference.
• For mutable access.
• Enables mutable coercion.

1use std::ops::{Deref, DerefMut};
2
3struct MyBox<T>(T);
4
5impl<T> Deref for MyBox<T> {
6    type Target = T;
7    fn deref(&self) -> &T {
8        &self.0
9    }
10}

Key: Deref enables smart pointer ergonomics.