#![warn(clippy::map_err_ignore)] #![allow(clippy::unnecessary_wraps)] use std::error::Error; use std::fmt; #[derive(Debug)] enum Errors { Ignored, } impl Error for Errors {} impl fmt::Display for Errors { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "Error") } } fn main() -> Result<(), Errors> { let x = u32::try_from(-123_i32); println!("{:?}", x.map_err(|_| Errors::Ignored)); // Should not warn you because you explicitly ignore the parameter // using a named wildcard value println!("{:?}", x.map_err(|_foo| Errors::Ignored)); Ok(()) }