E0170 - Error codes index
Description: Book listing all Rust error codes

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# Error code E0170

A pattern binding is using the same name as one of the variants of a type.

Erroneous code example:

    #![deny(warnings)]
    enum Method {
        GET,
        POST,
    }

    fn is_empty(s: Method) -> bool {
        match s {
            GET => true,
            _ => false
        }
    }

    fn main() {}

Enum variants are qualified by default. For example, given this type:

    #![allow(unused)]
    fn main() {
    enum Method {
        GET,
        POST,
    }
    }

You would match it using:

    #![allow(unused)]
    fn main() {
    enum Method {
        GET,
        POST,
    }

    let m = Method::GET;

    match m {
        Method::GET => {},
        Method::POST => {},
    }
    }

If you don’t qualify the names, the code will bind new variables named “GET” and “POST” instead. This behavior is likely not what you want, so `rustc` warns when that happens.

Qualified names are good practice, and most code works well with them. But if you prefer them unqualified, you can import the variants into scope:

    use Method::*;
    enum Method { GET, POST }
    fn main() {}

If you want others to be able to import variants from your module directly, use `pub use`:

    pub use Method::*;
    pub enum Method { GET, POST }
    fn main() {}