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#![feature(thin_box)]
// run-pass
use std::boxed::ThinBox;
use std::error::Error;
use std::{fmt, mem};
use std::ops::DerefMut;
const EXPECTED: &str = "boooo!";
fn main() {
let thin_error: ThinBox<dyn Error> = ThinBox::new_unsize(Foo);
assert_eq!(mem::size_of::<*const i32>(), mem::size_of_val(&thin_error));
let msg = thin_error.to_string();
assert_eq!(EXPECTED, msg);
let mut thin_concrete_error: ThinBox<Foo> = ThinBox::new(Foo);
assert_eq!(mem::size_of::<*const i32>(), mem::size_of_val(&thin_concrete_error));
let msg = thin_concrete_error.to_string();
assert_eq!(EXPECTED, msg);
let inner = thin_concrete_error.deref_mut();
let msg = inner.to_string();
assert_eq!(EXPECTED, msg);
}
#[derive(Debug)]
struct Foo;
impl fmt::Display for Foo {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", EXPECTED)
}
}
impl Error for Foo {}
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