remove the destructors table

src/librustc/middle/reachable.rs

@@ -348,13 +348,17 @@ impl<'a, 'tcx> ReachableContext<'a, 'tcx> {
     // this properly would result in the necessity of computing *type*
     // reachability, which might result in a compile time loss.
     fn mark_destructors_reachable(&mut self) {
-        for adt in self.tcx.adt_defs() {
-            if let Some(destructor_def_id) = adt.destructor() {
-                if destructor_def_id.is_local() {
-                    self.reachable_symbols.insert(destructor_def_id.node);
+        let drop_trait = match self.tcx.lang_items.drop_trait() {
+            Some(id) => self.tcx.lookup_trait_def(id), None => { return }
+        };
+        drop_trait.for_each_impl(self.tcx, |drop_impl| {
+            for destructor in &self.tcx.impl_items.borrow()[&drop_impl] {
+                let destructor_did = destructor.def_id();
+                if destructor_did.is_local() {
+                    self.reachable_symbols.insert(destructor_did.node);
                 }
             }
-        }
+        })
     }
 }
 

src/librustc/middle/ty/context.rs

@@ -245,9 +245,6 @@ pub struct ctxt<'tcx> {
     /// True if the variance has been computed yet; false otherwise.
     pub variance_computed: Cell<bool>,
 
-    /// A method will be in this list if and only if it is a destructor.
-    pub destructors: RefCell<DefIdSet>,
-
     /// Maps a DefId of a type to a list of its inherent impls.
     /// Contains implementations of methods that are inherent to a type.
     /// Methods in these implementations don't need to be exported.
@@ -475,7 +472,6 @@ impl<'tcx> ctxt<'tcx> {
             normalized_cache: RefCell::new(FnvHashMap()),
             lang_items: lang_items,
             provided_method_sources: RefCell::new(DefIdMap()),
-            destructors: RefCell::new(DefIdSet()),
             inherent_impls: RefCell::new(DefIdMap()),
             impl_items: RefCell::new(DefIdMap()),
             used_unsafe: RefCell::new(NodeSet()),

src/librustc/middle/ty/mod.rs

@@ -2329,11 +2329,6 @@ impl<'tcx> ctxt<'tcx> {
         self.lookup_adt_def_master(did)
     }
 
-    /// Return the list of all interned ADT definitions
-    pub fn adt_defs(&self) -> Vec<AdtDef<'tcx>> {
-        self.adt_defs.borrow().values().cloned().collect()
-    }
-
     /// Given the did of an item, returns its full set of predicates.
     pub fn lookup_predicates(&self, did: DefId) -> GenericPredicates<'tcx> {
         lookup_locally_or_in_crate_store(

src/librustc_lint/builtin.rs

@@ -1213,15 +1213,14 @@ impl LintPass for DropWithReprExtern {
 
 impl LateLintPass for DropWithReprExtern {
     fn check_crate(&mut self, ctx: &LateContext, _: &hir::Crate) {
-        for dtor_did in ctx.tcx.destructors.borrow().iter() {
-            let (drop_impl_did, dtor_self_type) =
-                if dtor_did.is_local() {
-                    let impl_did = ctx.tcx.map.get_parent_did(dtor_did.node);
-                    let ty = ctx.tcx.lookup_item_type(impl_did).ty;
-                    (impl_did, ty)
-                } else {
-                    continue;
-                };
+        let drop_trait = match ctx.tcx.lang_items.drop_trait() {
+            Some(id) => ctx.tcx.lookup_trait_def(id), None => { return }
+        };
+        drop_trait.for_each_impl(ctx.tcx, |drop_impl_did| {
+            if !drop_impl_did.is_local() {
+                return;
+            }
+            let dtor_self_type = ctx.tcx.lookup_item_type(drop_impl_did).ty;
 
             match dtor_self_type.sty {
                 ty::TyEnum(self_type_def, _) |
@@ -1247,6 +1246,6 @@ impl LateLintPass for DropWithReprExtern {
                 }
                 _ => {}
             }
-        }
+        })
     }
 }

src/librustc_typeck/check/method/confirm.rs

@@ -620,13 +620,7 @@ impl<'a,'tcx> ConfirmContext<'a,'tcx> {
             ty::TraitContainer(trait_def_id) => {
                 callee::check_legal_trait_for_method_call(self.fcx.ccx, self.span, trait_def_id)
             }
-            ty::ImplContainer(..) => {
-                // Since `drop` is a trait method, we expect that any
-                // potential calls to it will wind up in the other
-                // arm. But just to be sure, check that the method id
-                // does not appear in the list of destructors.
-                assert!(!self.tcx().destructors.borrow().contains(&pick.item.def_id()));
-            }
+            ty::ImplContainer(..) => {}
         }
     }
 

src/librustc_typeck/check/mod.rs

@@ -431,17 +431,19 @@ pub fn check_item_bodies(ccx: &CrateCtxt) {
 }
 
 pub fn check_drop_impls(ccx: &CrateCtxt) {
-    for drop_method_did in ccx.tcx.destructors.borrow().iter() {
-        if drop_method_did.is_local() {
-            let drop_impl_did = ccx.tcx.map.get_parent_did(drop_method_did.node);
+    let drop_trait = match ccx.tcx.lang_items.drop_trait() {
+        Some(id) => ccx.tcx.lookup_trait_def(id), None => { return }
+    };
+    drop_trait.for_each_impl(ccx.tcx, |drop_impl_did| {
+        if drop_impl_did.is_local() {
             match dropck::check_drop_impl(ccx.tcx, drop_impl_did) {
                 Ok(()) => {}
                 Err(()) => {
                     assert!(ccx.tcx.sess.has_errors());
                 }
             }
         }
-    }
+    });
 
     ccx.tcx.sess.abort_if_errors();
 }

src/librustc_typeck/coherence/mod.rs

@@ -126,7 +126,7 @@ impl<'a, 'tcx> CoherenceChecker<'a, 'tcx> {
         // Populate the table of destructors. It might seem a bit strange to
         // do this here, but it's actually the most convenient place, since
         // the coherence tables contain the trait -> type mappings.
-        self.populate_destructor_table();
+        self.populate_destructors();
 
         // Check to make sure implementations of `Copy` are legal.
         self.check_implementations_of_copy();
@@ -286,7 +286,7 @@ impl<'a, 'tcx> CoherenceChecker<'a, 'tcx> {
     // Destructors
     //
 
-    fn populate_destructor_table(&self) {
+    fn populate_destructors(&self) {
         let tcx = self.crate_context.tcx;
         let drop_trait = match tcx.lang_items.drop_trait() {
             Some(id) => id, None => { return }
@@ -309,9 +309,6 @@ impl<'a, 'tcx> CoherenceChecker<'a, 'tcx> {
                 ty::TyEnum(type_def, _) |
                 ty::TyStruct(type_def, _) => {
                     type_def.set_destructor(method_def_id.def_id());
-                    tcx.destructors
-                       .borrow_mut()
-                       .insert(method_def_id.def_id());
                 }
                 _ => {
                     // Destructors only work on nominal types.