Function combine::parser::error::unexpected

pub fn unexpected<I, S>(message: S) -> Unexpected<I, ()>where
    I: Stream,
    S: Into<Info<I::Item, I::Range>>,

Always fails with message as an unexpected error. Never consumes any input.

Has () the output type

let result = unexpected("token")
    .easy_parse("a");
assert!(result.is_err());
assert!(
    result.err()
        .unwrap()
        .errors
        .iter()
        .any(|m| *m == StreamError::unexpected("token".into()))
);