rustc: Implement parsing and typechecking for "once fn"

src/libsyntax/ast.rs

@@ -1059,6 +1059,25 @@ enum region_ {
     re_named(ident)
 }
 
+#[auto_serialize]
+#[auto_deserialize]
+enum Onceness {
+    Once,
+    Many
+}
+
+impl Onceness : cmp::Eq {
+    pure fn eq(other: &Onceness) -> bool {
+        match (self, *other) {
+            (Once, Once) | (Many, Many) => true,
+            _ => false
+        }
+    }
+    pure fn ne(other: &Onceness) -> bool {
+        !self.eq(other)
+    }
+}
+
 #[auto_serialize]
 #[auto_deserialize]
 enum ty_ {
@@ -1070,7 +1089,7 @@ enum ty_ {
     ty_ptr(mt),
     ty_rptr(@region, mt),
     ty_rec(~[ty_field]),
-    ty_fn(proto, purity, @~[ty_param_bound], fn_decl),
+    ty_fn(proto, purity, Onceness, @~[ty_param_bound], fn_decl),
     ty_tup(~[@Ty]),
     ty_path(@path, node_id),
     ty_fixed_length(@Ty, Option<uint>),