Is there a way to adjust the macro below, in order to detect when the last argument of the macro call is a closure? The code below works, but it’s using the trick of using a semicolon, and that doesn’t look right.

Could the closure argument be identified specifically at invocation, e.g. closure: || { ... }?

macro_rules! invoke_me {
    ($func_name:ident, $($arg:expr),*; || $closure:expr ) => {{
        println!("{}({})", stringify!($func_name), stringify!($($arg),*));
        println!("With closure");
        let result: Result<(),String> = $closure;
        result
    }};
    ($func_name:ident, $($arg:expr),*) => {{
        println!("{}({})", stringify!($func_name), stringify!($($arg),*));
        println!("No closure");
        Ok::<(),String>(())
    }};
}

fn main() {
    invoke_me!(foo, 1, 2, 3).unwrap();
    invoke_me!(foo, 1, 2, 3; || {
        println!("Ok from closure");
        Ok(())
    }).unwrap();
    let _ = invoke_me!(foo, 1, 2, 3; || {
        println!("Error from closure");
        Err("Error".to_string())
    });
}