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Author: arielb1

src/librustc/middle/ty.rs

@@ -258,15 +258,6 @@ pub struct field_ty {
     pub origin: ast::DefId,  // The DefId of the struct in which the field is declared.
 }
 
-// Contains information needed to resolve types and (in the future) look up
-// the types of AST nodes.
-#[derive(Copy, Clone, PartialEq, Eq, Hash)]
-pub struct creader_cache_key {
-    pub cnum: CrateNum,
-    pub pos: usize,
-    pub len: usize
-}
-
 #[derive(Clone, PartialEq, RustcDecodable, RustcEncodable)]
 pub struct ItemVariances {
     pub types: VecPerParamSpace<Variance>,
@@ -351,6 +342,30 @@ pub enum AutoAdjustment<'tcx> {
 /// }
 /// ```
 #[derive(Copy, Clone, Debug)]
+
+#[derive(Copy, PartialEq, Eq)]
+pub enum UnsizeKind {
+    Vtable,
+    Length
+}
+
+/// Returns the kind of unsize information of t, or None
+/// if t is sized or it is unknown.
+pub fn unsize_kind<'tcx>(cx: &ctxt<'tcx>,
+                         t: Ty<'tcx>)
+                         -> Option<UnsizeKind> {
+    match t.sty {
+        ty_vec(_, None) => Some(Length),
+        ty_trait(_) => Some(Vtable),
+        ty_struct(did, substs) => {
+            let last_field = struct_fields(cx, did, substs).pop();
+            last_field.map(|f| unsize_kind(f.mt.ty))
+        }
+        _ => None
+    }
+}
+
+#[derive(Clone, Debug)]
 pub struct AutoDerefRef<'tcx> {
     /// Step 1. Apply a number of dereferences, producing an lvalue.
     pub autoderefs: usize,
@@ -526,6 +541,15 @@ pub enum vtable_origin<'tcx> {
 // expr to the associated trait ref.
 pub type ObjectCastMap<'tcx> = RefCell<NodeMap<ty::PolyTraitRef<'tcx>>>;
 
+// Contains information needed to resolve types and (in the future) look up
+// the types of AST nodes.
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct creader_cache_key {
+    pub cnum: CrateNum,
+    pub pos: usize,
+    pub len: usize
+}
+
 /// A restriction that certain types must be the same size. The use of
 /// `transmute` gives rise to these restrictions. These generally
 /// cannot be checked until trans; therefore, each call to `transmute`