4 #![warn(clippy::match_as_ref)]
7 let owned: Option<()> = None;
8 let borrowed: Option<&()> = owned.as_ref();
10 let mut mut_owned: Option<()> = None;
11 let borrow_mut: Option<&mut ()> = mut_owned.as_mut();
15 use std::{error::Error, fmt, num::ParseIntError};
19 source: Option<ParseIntError>,
23 fn source(&self) -> Option<&(dyn Error + 'static)> {
24 self.source.as_ref().map(|x| x as _)
28 impl fmt::Display for E {
29 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {