Projection Changes

Author: arora-aman

hir-place-target.md

@@ -1,16 +1,16 @@
-We are going to be refactoring [HIR places] to capture sufficient detail for us to use them to describe the places that a closure captures. 
+We are going to be refactoring [HIR places] to capture sufficient detail for us to use them to describe the places that a closure captures.
 
 The expected target structure looks something like this:
 
 ```rust
 /// A reference to a particular place that appears in the source code
-struct PlaceReference<'tcx> {
+struct PlaceWithHirId<'tcx> {
     /// the place being referenced
     place: Place<'tcx>,
-    
+
     /// hir-id of source expression or pattern
     hir_id: HirId,
-    
+
     // Maybe no Span, since they're being removed from the Hir
 }
 
@@ -19,38 +19,44 @@ struct PlaceReference<'tcx> {
 struct Place<'tcx> {
     /// start of the place expression, typically a local variable
     base: PlaceBase,
-    
-    /// projections select parts of the base expression; e.g., 
+
+    /// Type of the Base
+    base_ty: Ty<'tcx>,
+
+    /// projections select parts of the base expression; e.g.,
     /// in the place expression `a.b.c`, `b` and `c` are projections
     projections: Vec<Projection<'tcx>>,
 }
 
-/// *Projections* select parts of the base expression; e.g., 
+/// *Projections* select parts of the base expression; e.g.,
 /// in the place expression `a.b.c`, `b` and `c` are projections
 struct Projection<'tcx> {
-    /// Type of the projection thus far.
-    ty: Ty<'tcx>,
-    
-    /// 
+    /// Type before the projection is applied.
+    before_ty: Ty<'tcx>,
+
+    /// type of the projection.
     kind: ProjectionKind,
+
+    /// Type after the projection is applied.
+    after_ty: Ty<'tcx>,
 }
 
 /// Kinds of projections
 enum ProjectionKind {
     /// `*B`, where `B` is the base expression
     Deref,
-    
+
     /// `B.F` where `B` is the base expression and `F` is
     /// the field. The field is identified by which variant
     /// it appears in along with a field index. The variant
     /// is used for enums.
     Field(Field, VariantIdx),
-    
+
     /// Some index like `B[x]`, where `B` is the base
     /// expression. We don't preserve the index `x` because
     /// we won't need it.
     Index,
-    
+
     /// A subslice covering a range of values like `B[x..y]`.
     Subslice,
 }