Suppress match_wildcard_for_single_variants clippy false positive
Suppress match_wildcard_for_single_variants clippy false positive

https://github.com/rust-lang/rust-clippy/issues/6984

    error: wildcard matches only a single variant and will also match any future added variants
        --> src/expr.rs:2337:17
         |
    2337 |                 _ => unreachable!(),
         |                 ^ help: try this: `Pat::__TestExhaustive(_)`
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#match_wildcard_for_single_variants

dtolnay/syn