3 files changed, 35 insertions, 10 deletions
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 0aaba81819b..a7b0ff45b97 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -120,9 +120,9 @@ impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Ty<'tcx> {
     }
 }
 
-impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for ty::PredicateKind<'tcx> {
+impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for ty::Binder<ty::PredicateKind<'tcx>> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
-        encode_with_shorthand(e, self, TyEncoder::predicate_shorthands)
+        encode_with_shorthand(e, &self.skip_binder(), TyEncoder::predicate_shorthands)
     }
 }
 
@@ -226,18 +226,18 @@ impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Ty<'tcx> {
     }
 }
 
-impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::PredicateKind<'tcx> {
-    fn decode(decoder: &mut D) -> Result<ty::PredicateKind<'tcx>, D::Error> {
+impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::Binder<ty::PredicateKind<'tcx>> {
+    fn decode(decoder: &mut D) -> Result<ty::Binder<ty::PredicateKind<'tcx>>, D::Error> {
         // Handle shorthands first, if we have an usize > 0x80.
-        if decoder.positioned_at_shorthand() {
+        Ok(ty::Binder::bind(if decoder.positioned_at_shorthand() {
             let pos = decoder.read_usize()?;
             assert!(pos >= SHORTHAND_OFFSET);
             let shorthand = pos - SHORTHAND_OFFSET;
 
-            decoder.with_position(shorthand, ty::PredicateKind::decode)
+            decoder.with_position(shorthand, ty::PredicateKind::decode)?
         } else {
-            Ok(ty::PredicateKind::decode(decoder)?)
-        }
+            ty::PredicateKind::decode(decoder)?
+        }))
     }
 }
 
@@ -471,3 +471,28 @@ macro_rules! implement_ty_decoder {
         }
     }
 }
+
+macro_rules! impl_binder_encode_decode {
+    ($($t:ty),+ $(,)?) => {
+        $(
+            impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for ty::Binder<$t> {
+                fn encode(&self, e: &mut E) -> Result<(), E::Error> {
+                    self.as_ref().skip_binder().encode(e)
+                }
+            }
+            impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::Binder<$t> {
+                fn decode(decoder: &mut D) -> Result<Self, D::Error> {
+                    Ok(ty::Binder::bind(Decodable::decode(decoder)?))
+                }
+            }
+        )*
+    }
+}
+
+impl_binder_encode_decode! {
+    &'tcx ty::List<Ty<'tcx>>,
+    ty::FnSig<'tcx>,
+    ty::ExistentialPredicate<'tcx>,
+    ty::TraitRef<'tcx>,
+    Vec<ty::GeneratorInteriorTypeCause<'tcx>>,
+}
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 88a2aac010c..099c5aa84e5 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1081,7 +1081,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
 #[derive(HashStable, TypeFoldable)]
 pub enum PredicateKind<'tcx> {
     /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index d43c5135d90..cdf443975f4 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -955,7 +955,7 @@ impl<'tcx> PolyExistentialTraitRef<'tcx> {
 /// erase, or otherwise "discharge" these bound vars, we change the
 /// type from `Binder<T>` to just `T` (see
 /// e.g., `liberate_late_bound_regions`).
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
 pub struct Binder<T>(T);
 
 impl<T> Binder<T> {