{"ast_node_type":"other","tokens":[{"end":96,"kind":"keyword","start":0,"text":"//"}]}
            // For each witness, we build a new pattern in the shape of `ctor(_, _, wit, _, _)`,
            let wits_for_col_i = collect_nonexhaustive_missing_variants(cx, col_i)?;
            // adding enough wildcards to match `arity`.