Rust dedupe Vec<T> without changing order

unique_keep_order.rs

use std::collections::HashSet;
use std::hash::Hash;

fn unique_keep_order<T: Eq + Hash + Clone>(vec: Vec<T>) -> Vec<T> {
    let mut seen = HashSet::new();
    let mut output = Vec::with_capacity(vec.len());

    for x in vec.into_iter() {
        if seen.insert(x.clone()) {
            output.push(x); // Use the original x
        }
    }

    output
}
  
fn main() {
    println!("{:?}", unique_keep_order(vec![1, 3, 1, 2, 2, 3]));
    println!("{:?}", unique_keep_order::<i32>(vec![]));
}  

To run in playground https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6641db6c9edfa8908334b7b814ec546e