1 files changed, 10 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 69ae05ca820..ddbc0bffaed 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -17,6 +17,7 @@ use crate::traits;
 use crate::ty::GenericArgsRef;
 use crate::ty::{self, AdtDef, Ty};
 use rustc_data_structures::fx::FxHashMap;
+use rustc_hir::def_id::LocalDefId;
 use rustc_middle::ty::TyCtxt;
 use rustc_serialize::{Decodable, Encodable};
 use rustc_span::Span;
@@ -431,6 +432,15 @@ impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for ty::List<Fi
     }
 }
 
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for ty::List<LocalDefId> {
+    fn decode(decoder: &mut D) -> &'tcx Self {
+        let len = decoder.read_usize();
+        decoder.interner().mk_local_def_ids_from_iter(
+            (0..len).map::<LocalDefId, _>(|_| Decodable::decode(decoder)),
+        )
+    }
+}
+
 impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
     for ty::List<(VariantIdx, FieldIdx)>
 {