Code shared from the Rust Playground

playground.rs

use chrono::*;

const SECOND_IN_MICROSECONDS: i64 = 1_000_000;
const MICROSECOND_IN_NANOSECONDS: i64 = 1_000;

fn s(μs: i64) -> i64 { (μs / SECOND_IN_MICROSECONDS) as i64 }
fn ns(μs: i64) -> u32 { (μs.rem_euclid(SECOND_IN_MICROSECONDS) * MICROSECOND_IN_NANOSECONDS) as u32 }

fn main() {
    let past_ms = -150_151_152_153_154;
    let future_ms = 150_151_152_153_154;
    let past = Utc.timestamp(s(past_ms), ns(past_ms));
    println!("{past}");
    let future = Utc.timestamp(s(future_ms), ns(future_ms));
    println!("{future}");
}

Related to Dart gist.