Create a module-reexports table.

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1086,14 +1086,10 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             }
         }
 
-        match self.kind(id) {
-            EntryKind::Mod(exports) => {
-                for exp in exports.decode((self, sess)) {
-                    callback(exp);
-                }
+        if let Some(exports) = self.root.tables.module_reexports.get(self, id) {
+            for exp in exports.decode((self, sess)) {
+                callback(exp);
             }
-            EntryKind::Enum | EntryKind::Trait => {}
-            _ => bug!("`for_each_module_child` is called on a non-module: {:?}", self.def_kind(id)),
         }
     }
 
@@ -1106,10 +1102,8 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     fn module_expansion(self, id: DefIndex, sess: &Session) -> ExpnId {
-        match self.kind(id) {
-            EntryKind::Mod(_) | EntryKind::Enum | EntryKind::Trait => {
-                self.get_expn_that_defined(id, sess)
-            }
+        match self.def_kind(id) {
+            DefKind::Mod | DefKind::Enum | DefKind::Trait => self.get_expn_that_defined(id, sess),
             _ => panic!("Expected module, found {:?}", self.local_def_id(id)),
         }
     }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1254,15 +1254,13 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         // code uses it). However, we skip encoding anything relating to child
         // items - we encode information about proc-macros later on.
         let reexports = if !self.is_proc_macro {
-            match tcx.module_reexports(local_def_id) {
-                Some(exports) => self.lazy_array(exports),
-                _ => LazyArray::empty(),
-            }
+            tcx.module_reexports(local_def_id).unwrap_or(&[])
         } else {
-            LazyArray::empty()
+            &[]
         };
 
-        record!(self.tables.kind[def_id] <- EntryKind::Mod(reexports));
+        record_array!(self.tables.module_reexports[def_id] <- reexports);
+        record!(self.tables.kind[def_id] <- EntryKind::Mod);
         if self.is_proc_macro {
             // 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));

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -399,6 +399,7 @@ define_tables! {
     proc_macro: Table<DefIndex, MacroKind>,
     // Slot is full when there is a self parameter.
     fn_has_self_parameter: Table<DefIndex, ()>,
+    module_reexports: Table<DefIndex, LazyArray<ModChild>>,
 }
 
 #[derive(Copy, Clone, MetadataEncodable, MetadataDecodable)]
@@ -421,7 +422,7 @@ enum EntryKind {
     Union,
     Fn,
     ForeignFn,
-    Mod(LazyArray<ModChild>),
+    Mod,
     MacroDef,
     ProcMacro,
     Closure,