add EarlyBinder::subst_identity; impl ParameterizedOverTcx (needed for rustc_metadata) and Value for EarlyBinder

Author: kylematsuda

compiler/rustc_middle/src/ty/parameterized.rs

@@ -32,6 +32,10 @@ impl<T: ParameterizedOverTcx> ParameterizedOverTcx for ty::Binder<'static, T> {
     type Value<'tcx> = ty::Binder<'tcx, T::Value<'tcx>>;
 }
 
+impl<T: ParameterizedOverTcx> ParameterizedOverTcx for ty::EarlyBinder<T> {
+    type Value<'tcx> = ty::EarlyBinder<T::Value<'tcx>>;
+}
+
 #[macro_export]
 macro_rules! trivially_parameterized_over_tcx {
     ($($ty:ty),+ $(,)?) => {

compiler/rustc_middle/src/ty/subst.rs

@@ -713,6 +713,10 @@ impl<'tcx, T: TypeFoldable<'tcx>> ty::EarlyBinder<T> {
         let mut folder = SubstFolder { tcx, substs, binders_passed: 0 };
         self.0.fold_with(&mut folder)
     }
+
+    pub fn subst_identity(self) -> T {
+        self.0
+    }
 }
 
 ///////////////////////////////////////////////////////////////////////////

compiler/rustc_middle/src/values.rs

@@ -94,6 +94,18 @@ impl<'tcx> Value<TyCtxt<'tcx>, DepKind> for Representability {
     }
 }
 
+impl<'tcx> Value<TyCtxt<'tcx>, DepKind> for ty::EarlyBinder<Ty<'_>> {
+    fn from_cycle_error(tcx: TyCtxt<'tcx>, cycle: &[QueryInfo<DepKind>]) -> Self {
+        ty::EarlyBinder(Ty::from_cycle_error(tcx, cycle))
+    }
+}
+
+impl<'tcx> Value<TyCtxt<'tcx>, DepKind> for ty::EarlyBinder<ty::Binder<'_, ty::FnSig<'_>>> {
+    fn from_cycle_error(tcx: TyCtxt<'tcx>, cycle: &[QueryInfo<DepKind>]) -> Self {
+        ty::EarlyBinder(ty::Binder::from_cycle_error(tcx, cycle))
+    }
+}
+
 // item_and_field_ids should form a cycle where each field contains the
 // type in the next element in the list
 pub fn recursive_type_error(