How to Avoid Memory Leaks in Rust (Yes, They're Possible)

Memory leaks in Rust occur when you intentionally leak memory using std::mem::forget or create reference cycles with Rc and RefCell that the garbage collector cannot break. To avoid leaks, ensure you drop references explicitly or use Weak pointers to break cycles in reference-counted smart pointers.

use std::rc::{Rc, Weak};
use std::cell::RefCell;

struct Node {
    value: i32,
    next: Option<Rc<RefCell<Node>>>,
    parent: Weak<RefCell<Node>>,
}

fn main() {
    let node = Rc::new(RefCell::new(Node {
        value: 5,
        next: None,
        parent: Rc::downgrade(&Rc::new(RefCell::new(Node { value: 0, next: None, parent: Weak::new() }))),
    }));
    // Memory is freed when 'node' goes out of scope because the cycle is broken by 'Weak'
}

Rust usually cleans up memory automatically, but leaks happen if you tell it to keep data forever or if two pieces of data hold onto each other in a loop. Think of it like two people holding hands in a circle; they can't let go because they are holding each other. Using a 'weak' link, like a handshake that doesn't grip tight, allows the system to eventually let go and clean up the memory.