Check for local types in writeback with debug assertions

Author: Zoxc

src/librustc/infer/outlives/free_region_map.rs

@@ -11,6 +11,10 @@ pub struct FreeRegionMap<'tcx> {
 }
 
 impl<'tcx> FreeRegionMap<'tcx> {
+    pub fn elements(&self) -> impl Iterator<Item=&Region<'tcx>> {
+        self.relation.elements()
+    }
+
     pub fn is_empty(&self) -> bool {
         self.relation.is_empty()
     }

src/librustc_data_structures/transitive_relation.rs

@@ -58,6 +58,10 @@ impl<T: Clone + Debug + Eq + Hash> TransitiveRelation<T> {
         self.edges.is_empty()
     }
 
+    pub fn elements(&self) -> impl Iterator<Item=&T> {
+        self.elements.iter()
+    }
+
     fn index(&self, a: &T) -> Option<Index> {
         self.map.get(a).cloned()
     }

src/librustc_typeck/check/writeback.rs

@@ -363,10 +363,8 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
     }
 
     fn visit_free_region_map(&mut self) {
-        let free_region_map = self.tcx()
-            .lift_to_global(&self.fcx.tables.borrow().free_region_map);
-        let free_region_map = free_region_map.expect("all regions in free-region-map are global");
-        self.tables.free_region_map = free_region_map;
+        self.tables.free_region_map = self.fcx.tables.borrow().free_region_map.clone();
+        debug_assert!(!self.tables.free_region_map.elements().any(|r| r.has_local_value()));
     }
 
     fn visit_user_provided_tys(&mut self) {
@@ -381,12 +379,10 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
                 local_id,
             };
 
-            let c_ty = if let Some(c_ty) = self.tcx().lift_to_global(c_ty) {
-                c_ty
-            } else {
+            if cfg!(debug_assertions) && c_ty.has_local_value() {
                 span_bug!(
                     hir_id.to_span(self.fcx.tcx),
-                    "writeback: `{:?}` missing from the global type context",
+                    "writeback: `{:?}` is a local value",
                     c_ty
                 );
             };
@@ -423,12 +419,10 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 
         for (&def_id, c_sig) in fcx_tables.user_provided_sigs.iter() {
-            let c_sig = if let Some(c_sig) = self.tcx().lift_to_global(c_sig) {
-                c_sig
-            } else {
+            if cfg!(debug_assertions) && c_sig.has_local_value() {
                 span_bug!(
                     self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
-                    "writeback: `{:?}` missing from the global type context",
+                    "writeback: `{:?}` is a local value",
                     c_sig
                 );
             };
@@ -743,20 +737,19 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         }
     }
 
-    fn resolve<T>(&self, x: &T, span: &dyn Locatable) -> T::Lifted
+    fn resolve<T>(&self, x: &T, span: &dyn Locatable) -> T
     where
-        T: TypeFoldable<'tcx> + ty::Lift<'tcx>,
+        T: TypeFoldable<'tcx>,
     {
         let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
-        if let Some(lifted) = self.tcx().lift_to_global(&x) {
-            lifted
-        } else {
+        if cfg!(debug_assertions) && x.has_local_value() {
             span_bug!(
                 span.to_span(self.fcx.tcx),
-                "writeback: `{:?}` missing from the global type context",
+                "writeback: `{:?}` is a local value",
                 x
             );
         }
+        x
     }
 }