Annotate-snippets

pub struct Message {
    level: Level,
    code: Option<&str>
    title: &str,
    snippets: Vec<Snippet>,
}

pub struct Snippet {
    origin: Option<&'a str>,
    line_start: usize,

    source: &'a str,
    annotations: Vec<Annotation>,

    elide_unannotated: bool,
}

pub struct Annotation {
    style: AnnotationStyle,
    span: Range<usize>,
    label: Option<&str>,
}

pub enum Level {
    Error,
    Warn,
    Info,
    Note,
    Help,
}

pub enum Style {
    Level,  // Primary
    Neutral,  // Secondary
    Added,
    Removed,
}

Level::Error
  .title("missing lifetime specifier")
  .code("E0106")
  .snippet(
    Snippet::new("fn short(foo_bar: &Vec<&i32>) -> &i32 {")
      .line_start(100)
      .origin("$DIR/multiline-multipart-suggestion.rs")
      .annotate(
          Style::Level.span(..4).label("expected named lifetime parameter")
      )
      .annotate(
          Style::Neutral.span(18..24)
      )
  )
Level::Help
  .title("this function's return type ...")
Level::Help
  .title("consider")
  .snippet(
    Snippet::new("source")
      .line_start(100)
      .origin("foo.rs")
      .annotate(
          Style::Added.span(1..4)
      )
      .annotate(
          Style::Added.span(10..13)
      )
      .annotate(
          Style::Added.span(17..19)
      )
      .annotate(
          Style::Added.span(20..23)
      )
  )