1 files changed, 5 insertions, 1 deletions
diff --git a/compiler/rustc_span/src/def_id.rs b/compiler/rustc_span/src/def_id.rs
index 162c15574..b2c58caff 100644
--- a/compiler/rustc_span/src/def_id.rs
+++ b/compiler/rustc_span/src/def_id.rs
@@ -1,13 +1,17 @@
 use crate::{HashStableContext, Symbol};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
+use rustc_data_structures::unhash::Unhasher;
 use rustc_data_structures::AtomicRef;
 use rustc_index::vec::Idx;
 use rustc_macros::HashStable_Generic;
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use std::borrow::Borrow;
 use std::fmt;
-use std::hash::{Hash, Hasher};
+use std::hash::{BuildHasherDefault, Hash, Hasher};
+
+pub type StableCrateIdMap =
+    indexmap::IndexMap<StableCrateId, CrateNum, BuildHasherDefault<Unhasher>>;
 
 rustc_index::newtype_index! {
     #[custom_encodable]