{"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
    // FIXME: It would be nice to have a less-awkward way to apply permutations,
fn permute<I: rustc_index::Idx + Ord, T>(data: &mut IndexVec<I, T>, map: &IndexSlice<I, I>) {
    // but I don't know one that exists. `sort_by_cached_key` has logic for it