[rust-dev] Patterns that'll never match

Tommi rusty.gates at icloud.com
Sun Jun 1 00:02:26 PDT 2014

Would it be possible to get a compile-time error for a `match` branch that can never be reached due to a previous branch encompassing it. For example, for the middle branch here:

let n = 0;
match n {
    x if x < 2 => (),
    x if x < 1 => (),
    _ => ()

If this is a too complicated a problem in the general case, then perhaps there could be warnings for some (implementation defined) simple cases.

More information about the Rust-dev mailing list