#![allow(dead_code, deprecated, unused_variables, unused_mut)]
#![feature(error_generic_member_access)]
use core::error::Request;
#[derive(Debug)]
struct SomeConcreteType {
    field: String,
}
impl std::fmt::Display for SomeConcreteType {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{} failed", self.field)
    }
}
impl std::error::Error for SomeConcreteType {
    fn provide<'a>(&'a self, request: &mut Request<'a>) {
        request.provide_value_with::<String>(|| self.field.clone());
    }
}
fn main() {}