1 use thiserror::Error; 2 3 #[derive(Error, Debug)] 4 #[error("error: {r#fn}")] 5 pub struct Error { 6 r#fn: &'static str, 7 } 8 main()9 fn main() { 10 let r#fn = "..."; 11 let _ = format!("error: {r#fn}"); 12 } 13