Prepare generator MutVisitor to have projections interned

Author: spastorino

src/librustc_mir/transform/generator.rs

@@ -88,6 +88,24 @@ impl<'tcx> MutVisitor<'tcx> for RenameLocalVisitor {
             *local = self.to;
         }
     }
+
+    fn visit_place(&mut self,
+                    place: &mut Place<'tcx>,
+                    context: PlaceContext,
+                    location: Location) {
+        self.visit_place_base(&mut place.base, context, location);
+
+        let new_projection: Vec<_> = place.projection.iter().map(|elem|
+            match elem {
+                PlaceElem::Index(local) if *local == self.from => {
+                    PlaceElem::Index(self.to)
+                }
+                _ => elem.clone(),
+            }
+        ).collect();
+
+        place.projection = new_projection.into_boxed_slice();
+    }
 }
 
 struct DerefArgVisitor;
@@ -110,7 +128,13 @@ impl<'tcx> MutVisitor<'tcx> for DerefArgVisitor {
                 projection: Box::new([ProjectionElem::Deref]),
             });
         } else {
-            self.super_place(place, context, location);
+            self.visit_place_base(&mut place.base, context, location);
+
+            for elem in place.projection.iter() {
+                if let PlaceElem::Index(local) = elem {
+                    assert_ne!(*local, self_arg());
+                }
+            }
         }
     }
 }
@@ -137,7 +161,13 @@ impl<'tcx> MutVisitor<'tcx> for PinArgVisitor<'tcx> {
                 projection: Box::new([ProjectionElem::Field(Field::new(0), self.ref_gen_ty)]),
             });
         } else {
-            self.super_place(place, context, location);
+            self.visit_place_base(&mut place.base, context, location);
+
+            for elem in place.projection.iter() {
+                if let PlaceElem::Index(local) = elem {
+                    assert_ne!(*local, self_arg());
+                }
+            }
         }
     }
 }
@@ -247,17 +277,25 @@ impl MutVisitor<'tcx> for TransformVisitor<'tcx> {
         assert_eq!(self.remap.get(local), None);
     }
 
-    fn visit_place(&mut self,
-                    place: &mut Place<'tcx>,
-                    context: PlaceContext,
-                    location: Location) {
+    fn visit_place(
+        &mut self,
+        place: &mut Place<'tcx>,
+        context: PlaceContext,
+        location: Location,
+    ) {
         if let PlaceBase::Local(l) = place.base {
             // Replace an Local in the remap with a generator struct access
             if let Some(&(ty, variant_index, idx)) = self.remap.get(&l) {
                 replace_base(place, self.make_field(variant_index, idx, ty));
             }
         } else {
-            self.super_place(place, context, location);
+            self.visit_place_base(&mut place.base, context, location);
+
+            for elem in place.projection.iter() {
+                if let PlaceElem::Index(local) = elem {
+                    assert_ne!(*local, self_arg());
+                }
+            }
         }
     }