Code shared from the Rust Playground

playground.rs

// 1. Run as-is.
// 2. Comment in the section marked (2). Read the compiler error.
// 3. Comment in the section marked (3). Look how output differs from (1).

use std::mem;

fn print_size_of<T>(_t: &T) {
    println!("size: {}", mem::size_of::<T>());
}

fn main() {
    let print_xs;
    {
        let xs = vec![1, 2, 3, 4];
        print_xs = /* (3) move */ || {
            for (i, x) in xs.iter().enumerate() {
                println!("{}: {}", i, x);
            }
        };
        print_size_of(&print_xs);
    }
    /* (2) print_xs(); */
}