Rust 如何从 many0 传播 Nom 失败上下文

我有一个NOM解析器，它可以解析字符串，但无法解析关键字.

当给定关键字时，下面的解析器会正确地失败.

但是，由于遇到关键字而导致失败的错误消息不会传播.

问题是，当label人失败时，many0(label)人成功了，但结果少了一个.随后，eof失败，因为并非所有内容都已解析.此操作会正确失败，但会丢失错误消息.

如何传播本地错误消息？

(See below code on 100.)

use nom::bytes::complete::{take_while, take_while1};
use nom::error::{VerboseError};
use nom::multi::{many0};
use nom::{IResult};
use nom::error::{context};
use nom::combinator::{eof, fail};

type ParseResult<'input, Out> = IResult<&'input str, Out, VerboseError<&'input str>>;

fn label(s1: &str) -> ParseResult<&str> {
    let (s2, a) = take_while1(|c: char| c.is_alphabetic())(s1)?;
    let (s3, _) = take_while(|c: char| c.is_whitespace())(s2)?;
    if a == "derp" {
        return context("this message is lost", fail)(s1);
    }
    Ok((s3, a))
}

fn parse(s: &str) -> ParseResult<Vec<&str>> {
    let (s, labels) = many0(label)(s)?;
    let (s, _) = eof(s)?;
    Ok((s, labels))
}

fn main() {
    println!("{:?}", parse("foo bar herp flerp"));
    // Ok(("", ["foo", "bar", "herp", "flerp"]))

    // This fails with Nom(Eof), both Nom(Fail) and context is lost
    println!("{:?}", parse("foo bar herp derp"));
    // Err(Error(VerboseError { errors: [("derp", Nom(Eof))] }))
}