thiserror

A crate that writes the Error and Display boilerplate for your error types.

thiserror's #[derive(Error)] implements std::error::Error, Display (from #[error(...)]), and From (from #[from]) for an error type; it adds nothing to the public API.

Examples

#[derive(Debug, thiserror::Error)] on enum ConfigError with #[error("unknown setting {0}")] UnknownKey(String) writes the Display and Error impls for you.
#[error(transparent)] Io(#[from] std::io::Error) also writes From<io::Error>, so ? converts an I/O error into ConfigError::Io.