Issue when pattern matching on tuples using guards

[aochagavia]

The code:

fn main() {
    let (name, street) = ("John".to_str(), "Something".to_str());
    match (name, street) {
        (ref n, s) if *n == "...".to_str() => (),
        _ => ()
    }
}

The error message:

test.rs:4:17: 4:18 error: cannot bind by-move into a pattern guard
test.rs:4         (ref n, s) if *n == "...".to_str() => (),
                          ^
error: aborting due to previous error

This forces you to use ref s to satisfy the compiler, but s is not used at all in the pattern guard! I think it this code should compile without ref s.

[alexcrichton]

Closing, this is just a fact of rustc right now. You're not allowed to move in a pattern with a guard. For relaxing these restrictions, rust-lang/rfcs#107 seems to do the trick.