create_maybe_sub_type.rs

create_maybe_sub_type.rs

fn create_maybe_sub_type(args: &PathArguments, span_range: &SpanRange) -> Option<Type> {
    match args {
        PathArguments::None => None,
        PathArguments::AngleBracketed(ref args) => {
            let arg = first_and_only(args.args.iter()).unwrap_or_else(|| {
                abort!(span_range, "Expected at exactly one generic parameter.")
            });
            if let GenericArgument::Type(sub_type2) = arg {
                Some(sub_type2.clone())
            } else {
                abort!(span_range, "Expected generic parameter to be a type.")
            }
        }
        PathArguments::Parenthesized(_) => {
            abort!(span_range, "Expected <..> generic parameter.")
        }
    }
}