相关疑难解决方法(0)

我想要一个随机数发生器.既然OsRng::new()可能会失败,我想回到以下情况,thread_rng()如果我必须:

extern crate rand; // 0.6.5

use rand::{rngs::OsRng, thread_rng, RngCore};

fn rng() -> impl RngCore {
    match OsRng::new() {
        Ok(rng) => rng,
        Err(e) => thread_rng(),
    }
}

但是,我收到此错误消息,我无法理解:

error[E0308]: match arms have incompatible types
 --> src/lib.rs:6:5
  |
6 | /     match OsRng::new() {
7 | |         Ok(rng) => rng,
8 | |         Err(e) => thread_rng(),
  | |                   ------------ match arm with an incompatible type
9 | |     }
  | |_____^ expected struct `rand::rngs::OsRng`, found struct `rand::prelude::ThreadRng` …