What is reborrowing in Rust

Reborrowing is an automatic Rust mechanism that creates a temporary reference from an existing one to satisfy function signatures without consuming the original reference.

Reborrowing is an automatic coercion where the compiler creates a new, temporary reference from an existing one to satisfy a function's expected type without moving the original reference.

fn takes_mut(x: &mut i32) {}

fn main() {
    let mut val = 5;
    let ref1 = &mut val;
    let ref2 = &mut val;
    
    // Reborrowing happens here: ref1 is not moved, a new &mut is created
    takes_mut(ref1); 
    takes_mut(ref1); // ref1 is still usable
}

This mechanism allows you to pass a mutable reference to multiple functions sequentially or convert &mut T to &T without consuming the original reference.

Reborrowing is like lending a book to a friend who immediately lends it to someone else; the original owner still has the book and can lend it again later. It matters because it lets you use a reference multiple times in a row without the compiler thinking you've given it away permanently. You use it whenever you pass a reference to a function that expects a reference, allowing the original variable to remain usable afterward.