macro_rules! reg_conflicts {
    (
                $(
                    $w:ident : $l:ident $h:ident
                ),*;
                $(
                    $w2:ident : $l2:ident
                ),*;
                $(
                    $x:ident : $y:ident : $z:ident
                ),*;
            ) => { ... };
}