rust中的thiserror详细理解

use anyhow::{bail, Context, Error, Result};
use std::{boxed, fs};
use std::io::Read;
use thiserror::Error;

// #[derive(Clone, Debug, Eq, Error, PartialEq)]
// #[error("Found no username in {0}")]
#[derive(Debug,Error)]
#[error("Found no username in {0}")]
struct EmptyUsernameError(String);

fn read_username(path: &str) ->Box<dyn std::error::Error>{

        return Box::new(EmptyUsernameError(path.to_string()));

}

fn main() {
    //fs::write("config.dat", "").unwrap();
    println!("{:?}", read_username("config.dat")) ;
}

结合https://docs.rs/thiserror/latest/thiserror/ 一起看。

#derive(Debug,Error) #error("Found no username in {0}")

这两个缺一不可