fn foo<S: Into<String>>(s: S) {
    let s = s.into();
    let ptr: *const str = s.as_str();
    println!("after: {:?}", ptr);
}

fn main() {
    let s = "test".to_string();
    let ptr: *const str = s.as_str();
    println!("after: {:?}", ptr);
    foo(s);
}