{"ast_node_type":"other","tokens":[{"end":77,"kind":"keyword","start":0,"text":"pats!(@fields(idx:0,"}]}
        pats!(@fields(idx:0, vec:fields, sub_tys:ctor_sub_tys) ,$($fields)*);
        // Parse subpatterns (note the leading comma).
        let arity = ctor_sub_tys.len();