`target/debug/error-handling` thread 'main' panicked at src/main.rs:8:23: Problem opening the file: Os { code: 2, kind: NotFound, message: "No such file or directory" } note: run with `RUST_BACKTRACE=1` environment 调用 panic! 时提供的 错误信息： thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/main.rs:4:49 同样，expect 方法也允许我们自定义 息。它看起来像这样： thread 'main' panicked at src/main.rs:5:10: hello.txt should be included in this project: Os { code: 2, kind: NotFound, message: "No such file or directory" } 在生产级别的代码中，大部分 Rustaceans 选择 expect 而不是