代码如下

fn load_proxies(filename:String)->std::io::Result<Vec<String>>{
    let mut proxies:Vec<String>=vec![];
    let file=File::open(filename)?;
    let reader=BufReader::new(&file);
    let mut cnt=0;
    let mut handle=vec![];
    crossbeam::scope( |scope| {
    for x in reader.lines() {
        let line = match x {
            Ok(t) => t,
            Err(e) => return Err(e)
        };
        let tmp = vec![line.clone()];
        handle.push(scope.spawn(move || { check_proxy(line) }));
    }
    for x in handle{
        let res=x.join();
        if res.1{
            proxies.push(res.0);
        }
    }
    });
    Ok(proxies)
}

编译器提示

error[E0308]: mismatched types
   --> src\main.rs:392:9
    |
392 | /         for x in handle{
393 | |             let res=x.join();
394 | |             if res.1{
395 | |                 proxies.push(res.0);
396 | |             }
397 | |         }
    | |_________^ expected enum 
`std::result::Result`, found ()
    |
    = note: expected type `std::result::Result<_,std::io::Error>`
               found type `()`

问题是我的闭包并没有返回任何东西，而且文档里面的签名也是

pub fn scope<'a, F, R>(f: F) -> R where
    F: FnOnce(&Scope<'a>) -> R, 

所以哪里有问题？

楼主自己发现问题了……闭包里面确实返回了Result，修改后即可