Borrowed data escapes outside of method

[weiying-chen]

I want to exit Termion's raw mode with drop(stdout) before exiting the process. But I'm doing it inside a spawned thread, and with stdout of type &mut impl Write.

This is a runnable simplified version of the code:

use std::{io::Write, time::Duration};

pub struct CmdRunner {}

impl CmdRunner {
    // there a `new()` method in the original code

    pub fn run(&mut self, stdout: &mut impl Write) {
        // code that runs the command

        let ctrl_c_pressed = false;

        std::thread::spawn(move || {
            if ctrl_c_pressed {
                // I want to use `drop(stdout)` here to exit Termion's raw mode.
                write!(stdout, "Exit raw mode").unwrap();           
                std::process::exit(0);
            }
        });

        std::thread::sleep(Duration::from_secs(5));

        write!(stdout, "Command executed successfully").unwrap();

        stdout.flush().unwrap();
    }
}

fn main() {
    let mut cmd_runner = CmdRunner {};
    let mut stdout = Vec::new();

    cmd_runner.run(&mut stdout);

    println!("stdout: {:?}", String::from_utf8_lossy(&stdout).to_string());
}

This produced this compile error:

impl Write cannot be sent between threads safely
required because it appears within the type &mut impl Write

So I added: pub fn run(&mut self, stdout: &mut (impl Write + std::marker::Send))

But now I'm getting this error:

borrowed data escapes outside of method
stdout escapes the method body here
borrowed data escapes outside of method
argument requires that '1 must outlive 'static

Rust Playground

[H2CO3]

This is the classic problem with thread::spawn(): the spawned closure can outlive the spawning function (in fact, it might live for an arbitrarily long time, hence it must be 'static). You should use thread::scope() instead: Rust Explorer

[jofas]

Please add a link to your original question when you cross-post (to avoid duplicated effort by the community):

impl Write cannot be sent between threads safely

[weiying-chen]

I wanted to, but I got this error:

An error occurred: Sorry, new users can only put 2 links in a post.

[weiying-chen]

Thanks! This solution is a lot easier than using Arc<Mutex<_>> (as other person suggested).