`defer` in pure rust

defer.rs

struct Defer<F: FnMut() + Sized>(F);

macro_rules! defer {
    ($($f: expr);+) => { let _d = Defer(|| {$($f);+}); } 
}

impl<F:FnMut() + Sized> Drop for Defer<F> {
    fn drop(&mut self) {
        (self.0)()
    }
}

fn main() {
    defer! { println!("coucou1"); println!(" (ending coucou1)"); };
    defer! { println!("coucou2") };
    println!("start");    
}