};
use crate::infer::InferCtxt;
use rustc_middle::ty::flags::FlagComputation;
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder};
+use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
use rustc_middle::ty::subst::GenericArg;
use rustc_middle::ty::{self, BoundVar, InferConst, List, Ty, TyCtxt, TypeFlags};
use std::sync::atomic::Ordering;