为什么我会溢出评估要求`Sized`&#34;当使用tokio_io的read_exact与Rc <tcpstream>?

时间:2018-05-05 13:27:46

标签: rust

已经发布了相当多的类似错误:

My case更简单,看起来很无辜:

extern crate tokio_core;
extern crate tokio_io;

use std::{borrow::Borrow, rc::Rc};
use tokio_core::net::TcpStream;
use tokio_io::io::read_exact;

fn read_one(conn: Rc<TcpStream>) {
    read_exact(conn.borrow(), [0u8]);
}

它给出了这个错误:

error[E0275]: overflow evaluating the requirement `_: std::marker::Sized`
 --> src/main.rs:9:5
  |
9 |     read_exact(conn.borrow(), [0u8]);
  |     ^^^^^^^^^^
  |
  = help: consider adding a `#![recursion_limit="128"]` attribute to your crate
  = note: required because of the requirements on the impl of `std::io::Read` for `&tokio_core::reactor::poll_evented2::PollEvented<_>`
  = note: required because of the requirements on the impl of `std::io::Read` for `&tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<_>>`
  = note: required because of the requirements on the impl of `std::io::Read` for `&tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<_>>>`
[... snip ...]
  = note: required because of the requirements on the impl of `std::io::Read` for `&tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<_>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
  = note: required because of the requirements on the impl of `tokio_io::AsyncRead` for `&tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<tokio_core::reactor::poll_evented2::PollEvented<_>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
  = note: required by `tokio_io::io::read_exact`

发生了什么事?

我知道以下工作,它比上面的更简单:

read_exact(&*conn, [0u8]);

我相信conn.borrow也应该有用,我只是不明白为什么会出现这个错误。

0 个答案:

没有答案