// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. use std::io; struct MyError(()); // doesn't implement Debug #[derive(Debug)] struct MyErrorWithParam<T> { x: T, } fn main() { let res: Result<i32, ()> = Ok(0); let _ = res.unwrap(); res.ok().expect("disaster!"); // the following should not warn, since `expect` isn't implemented unless // the error type implements `Debug` let res2: Result<i32, MyError> = Ok(0); res2.ok().expect("oh noes!"); let res3: Result<u32, MyErrorWithParam<u8>> = Ok(0); res3.ok().expect("whoof"); let res4: Result<u32, io::Error> = Ok(0); res4.ok().expect("argh"); let res5: io::Result<u32> = Ok(0); res5.ok().expect("oops"); let res6: Result<u32, &str> = Ok(0); res6.ok().expect("meh"); }