Expected struct <FOOBAR>, found <OTHER_LAZY_STATIC_REF>

[jens1o]

lazy_static! {
    static ref FIREFOX_REGEX: Regex = { Regex::new(r"firefox/([\d\.]+)").unwrap() };
    static ref EDGE_REGEX: Regex = { Regex::new(r"edge/(\d{2}\.\d+)").unwrap() };
    static ref BROWSER_LIST: HashMap<&'static str, Regex> = {
        let m: HashMap<&'static str, Regex> = HashMap::new();

        m.insert("Firefox", FIREFOX_REGEX);
        // -----------------^^^^^^^^^^^^^
        // expected struct Regex, found struct FIREFOX_REGEX
        m.insert("Edge", EDGE_REGEX);
        // --------------^^^^^^^^^^
        // expected struct Regex, found struct EDGE_REGEX

        m
    };
}

I don't understand that. I don't understand that.

[KodrAus]

Hi @jens1o! the problem here is that each static ref is actually lying about its type. So FIREFOX_REGEX and EDGE_REGEX aren't Regexes, they're some type that we can dereference to a Regex. To add them to your browser list we need to dereference them. So with some tweaking we can make your example work:

lazy_static! {
    static ref FIREFOX_REGEX: Regex = { Regex::new(r"firefox/([\d\.]+)").unwrap() };
    static ref EDGE_REGEX: Regex = { Regex::new(r"edge/(\d{2}\.\d+)").unwrap() };
    static ref BROWSER_LIST: HashMap<&'static str, &'static Regex> = {
        let mut m = HashMap::new();

        m.insert("Firefox", &*FIREFOX_REGEX);
        m.insert("Edge", &*EDGE_REGEX);

        m
    };
}

[jens1o]

Oh okay. Is it possible to make the error message more clearer? Thanks!

[KodrAus]

It's a bit confusing, isn't it. I think the best way we could improve the error messages here is by requiring the actual type name in the static. That way you know what you're looking at. This is something @matklad's alternative API for statics with complex initialisation does.

[KodrAus]

Thanks again for the input @jens1o!

I'll go ahead and close this one now as something that's solved by #111, depending on what direction that goes in.