Why rustfmt removes curly braces ? And how to prevent it ?

[yguel]

I have 2 code pieces, one where rustfmt removes curly braces and one where it does not and it annoys me.
It may be of no consequences, but I still fill confused by it especially because the output seems less readable to me.

First example where rustfmt does not remove curly braces

use std::thread;
use std::time::Duration;

fn main() {
    let handle = thread::spawn(|| {
        for i in 1..10 {
            println!("hi number {} from the spawned thread!", i);
            thread::sleep(Duration::from_millis(1));
        }
    });
    for i in 1..5 {
        println!("hi number {} from the main thread!", i);
        thread::sleep(Duration::from_millis(1));
    }

    handle.join().unwrap();
}

Here is the second code before use of rustfmt:

use std::thread;
use std::time::Duration;

fn main() {
    let handle = thread::spawn(|| {
        loop {
            println!("hi from the spawned thread!");
            thread::sleep(Duration::from_millis(1));
        }
    });

    for i in 1..5 {
        println!("hi number {} from the main thread!", i);
        thread::sleep(Duration::from_millis(1));
    }

    handle.join().unwrap();
}

And now the code after rustfmt pass (the loop statement changes):

use std::thread;
use std::time::Duration;

fn main() {
    let handle = thread::spawn(|| loop {
        println!("hi from the spawned thread!");
        thread::sleep(Duration::from_millis(1));
    });

    for i in 1..5 {
        println!("hi number {} from the main thread!", i);
        thread::sleep(Duration::from_millis(1));
    }

    handle.join().unwrap();
}

I like the fact that the closure is presented in its own block even if its only a loop block.
Furthermore, I very hate that a tool is removing some code even if it is unnecessary braces. I would prefer suggestions for that.
I would love to configure rustfmt to not remove code at all and just work on indentation. Is there an option for that ?