Which fragment does not incur memory allocations while writing to a "file" (represented by a Vec)?

use std::collections::HashMap;
fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut v = Vec::<u8>::new();
    let a = "LinkedIn";
    let b = 123;
    let c = '🧀';
    // replace this line
    println!("{:?}", v);
    Ok(())
}