Rust trait generic over all types of string references

generic_str.rs

pub trait GenericStr {
    fn as_str_generic(&self) -> &str;
}

impl GenericStr for &String {
    fn as_str_generic(&self) -> &str {
        self.as_str()
    }
}

impl GenericStr for String {
    fn as_str_generic(&self) -> &str {
        self.as_str()
    }
}

impl GenericStr for &str {
    fn as_str_generic(&self) -> &str {
        *self
    }
}

fn foo<S: GenericStr>(input: S) -> String {
    format!("you gave me: {}", input.as_str_generic())
}

fn main() {
    println!("{}", foo(String::from("a String")));
    println!("{}", foo(&String::from("a &String")));
    println!("{}", foo(String::from("a &str").as_str()));
    println!("{}", foo("a &'static str"));
}

Don't use this, use AsRef<str>:

fn foo<S: AsRef<str>>(input: S) -> String {
    format!("you gave me: {}", input.as_ref())
}