Fix incremental compilation.

Author: cjgillot

src/librustc_metadata/rmeta/decoder.rs

@@ -798,7 +798,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         )
     }
 
-    fn get_adt_def(&self, item_id: DefIndex, tcx: TyCtxt<'tcx>) -> ty::AdtDef {
+    fn get_adt_def(&self, item_id: DefIndex, tcx: TyCtxt<'tcx>) -> &'tcx ty::AdtDef {
         let kind = self.kind(item_id);
         let did = self.local_def_id(item_id);
 

src/librustc_middle/arena.rs

@@ -12,8 +12,11 @@ macro_rules! arena_types {
     ($macro:path, $args:tt, $tcx:lifetime) => (
         $macro!($args, [
             [] layouts: rustc_target::abi::Layout,
+            // AdtDef are interned and compared by address
+            [] adt_def: rustc_middle::ty::AdtDef,
             [decode] tables: rustc_middle::ty::TypeckTables<$tcx>,
             [] const_allocs: rustc_middle::mir::interpret::Allocation,
+            // Required for the incremental on-disk cache
             [few, decode] mir_keys: rustc_hir::def_id::DefIdSet,
             [] region_scope_tree: rustc_middle::middle::region::ScopeTree,
             [] dropck_outlives:

src/librustc_middle/query/mod.rs

@@ -282,8 +282,7 @@ rustc_queries! {
         query trait_def(_: DefId) -> ty::TraitDef {
             storage(ArenaCacheSelector<'tcx>)
         }
-        query adt_def(_: DefId) -> ty::AdtDef {
-            storage(ArenaCacheSelector<'tcx>)
+        query adt_def(_: DefId) -> &'tcx ty::AdtDef {
         }
         query adt_destructor(_: DefId) -> Option<ty::Destructor> {}
 

src/librustc_middle/ty/context.rs

@@ -1008,8 +1008,8 @@ impl<'tcx> TyCtxt<'tcx> {
         kind: AdtKind,
         variants: IndexVec<VariantIdx, ty::VariantDef>,
         repr: ReprOptions,
-    ) -> ty::AdtDef {
-        ty::AdtDef::new(self, did, kind, variants, repr)
+    ) -> &'tcx ty::AdtDef {
+        self.arena.alloc(ty::AdtDef::new(self, did, kind, variants, repr))
     }
 
     pub fn intern_const_alloc(self, alloc: Allocation) -> &'tcx Allocation {

src/librustc_typeck/collect.rs

@@ -861,7 +861,7 @@ fn convert_variant(
     )
 }
 
-fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtDef {
+fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
     use rustc_hir::*;
 
     let def_id = def_id.expect_local();