use rustc_middle::ty::relate::TypeRelation;
use rustc_middle::ty::subst::{Subst, SubstsRef};
use rustc_middle::ty::{self, EarlyBinder, PolyProjectionPredicate, ToPolyTraitRef, ToPredicate};
-use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable, TypeVisitable};
use rustc_span::symbol::sym;
use std::cell::{Cell, RefCell};