4 files changed, 9 insertions, 12 deletions
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index ca9daa49aa2..1e2b4aaef80 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -1219,10 +1219,11 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     fn module_expansion(&self, id: DefIndex, sess: &Session) -> ExpnId {
-        if let EntryKind::Mod(m) = self.kind(id) {
-            m.decode((self, sess)).expansion
-        } else {
-            panic!("Expected module, found {:?}", self.local_def_id(id))
+        match self.kind(id) {
+            EntryKind::Mod(_) | EntryKind::Enum(_) | EntryKind::Trait(_) => {
+                self.get_expn_that_defined(id, sess)
+            }
+            _ => panic!("Expected module, found {:?}", self.local_def_id(id)),
         }
     }
 
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 20f7b059b56..08d9db381cf 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1086,11 +1086,13 @@ impl EncodeContext<'a, 'tcx> {
             Lazy::empty()
         };
 
-        let data = ModData { reexports, expansion: tcx.expn_that_defined(local_def_id) };
+        let data = ModData { reexports };
 
         record!(self.tables.kind[def_id] <- EntryKind::Mod(self.lazy(data)));
         if self.is_proc_macro {
             record!(self.tables.children[def_id] <- &[]);
+            // Encode this here because we don't do it in encode_def_ids.
+            record!(self.tables.expn_that_defined[def_id] <- tcx.expn_that_defined(local_def_id));
         } else {
             record!(self.tables.children[def_id] <- md.item_ids.iter().map(|item_id| {
                 item_id.def_id.local_def_index
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 42855e9d9d1..40c497044de 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -367,7 +367,6 @@ struct RenderedConst(String);
 #[derive(MetadataEncodable, MetadataDecodable)]
 struct ModData {
     reexports: Lazy<[Export]>,
-    expansion: ExpnId,
 }
 
 #[derive(MetadataEncodable, MetadataDecodable)]
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 2a562a06cb3..c215de5560a 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -145,12 +145,7 @@ impl<'a> Resolver<'a> {
                     } else {
                         def_key.disambiguated_data.data.get_opt_name().expect("module without name")
                     };
-                    let expn_id = if def_kind == DefKind::Mod {
-                        self.cstore().module_expansion_untracked(def_id, &self.session)
-                    } else {
-                        // FIXME: Parent expansions for enums and traits are not kept in metadata.
-                        ExpnId::root()
-                    };
+                    let expn_id = self.cstore().module_expansion_untracked(def_id, &self.session);
 
                     Some(self.new_module(
                         parent,