Macro borrowing problem

macro_borrowing_problem.rs

macro_rules! get_body_as {
	($structure:ty, $req:expr, $error_fn:ident) => {
		{
			let body = get_body!($req, $error_fn);

			let raw_structure = borrow_function(&body);

			match raw_structure {
				Ok(structure) => structure,
				Err(error) => "Error"
			}
		}
	}
}

macro_rules! get_body {
	($req:expr, $error_fn:ident) => {
		{
			let mut payload = String::new();

			payload
		}
	}
}

fn borrow_function(s: &str) -> Result<&str, &str> {
    Ok(s)
}
fn main() {
    let function1 = |s: &str| s;
    let body = get_body_as!(&str, "Hello", function1);
    println!("Hello");
}