diff --git a/compiler/stable_mir/src/fold.rs b/compiler/stable_mir/src/fold.rs
index 90853c104bb..65b743811ce 100644
--- a/compiler/stable_mir/src/fold.rs
+++ b/compiler/stable_mir/src/fold.rs
@@ -1,9 +1,6 @@
 use std::ops::ControlFlow;
 
-use crate::{
-    ty::{self, BoundRegion, BoundRegionKind},
-    Opaque,
-};
+use crate::Opaque;
 
 use super::ty::{
     Allocation, Binder, Const, ConstDef, ConstantKind, ExistentialPredicate, FnSig, GenericArgKind,
@@ -116,36 +113,8 @@ impl Foldable for Region {
     fn fold<V: Folder>(&self, folder: &mut V) -> ControlFlow<V::Break, Self> {
         folder.fold_reg(self)
     }
-    fn super_fold<V: Folder>(&self, folder: &mut V) -> ControlFlow<V::Break, Self> {
-        let mut kind = self.kind.clone();
-        match &mut kind {
-            crate::ty::RegionKind::ReEarlyBound(_) => {}
-            crate::ty::RegionKind::ReLateBound(_, bound_reg) => {
-                *bound_reg = bound_reg.fold(folder)?
-            }
-            crate::ty::RegionKind::ReStatic => {}
-            crate::ty::RegionKind::RePlaceholder(bound_reg) => {
-                bound_reg.bound = bound_reg.bound.fold(folder)?
-            }
-            crate::ty::RegionKind::ReErased => {}
-        }
-        ControlFlow::Continue(ty::Region { kind: kind }.into())
-    }
-}
-
-impl Foldable for BoundRegion {
-    fn super_fold<V: Folder>(&self, folder: &mut V) -> ControlFlow<V::Break, Self> {
-        ControlFlow::Continue(BoundRegion { var: self.var, kind: self.kind.fold(folder)? })
-    }
-}
-
-impl Foldable for BoundRegionKind {
-    fn super_fold<V: Folder>(&self, _folder: &mut V) -> ControlFlow<V::Break, Self> {
-        match self {
-            BoundRegionKind::BrAnon => ControlFlow::Continue(self.clone()),
-            BoundRegionKind::BrNamed(_, _) => ControlFlow::Continue(self.clone()),
-            BoundRegionKind::BrEnv => ControlFlow::Continue(self.clone()),
-        }
+    fn super_fold<V: Folder>(&self, _: &mut V) -> ControlFlow<V::Break, Self> {
+        ControlFlow::Continue(self.clone())
     }
 }