* dropnzero_val fn added

* zero-mem for not needed drop situation placed in Ignore

Author: vertexclique

src/rustc/middle/trans/datum.rs

@@ -542,6 +542,25 @@ impl Datum {
         };
     }
 
+    fn dropnzero_val(bcx: block) -> block {
+        if !ty::type_needs_drop(bcx.tcx(), self.ty) {
+            return bcx;
+        }
+
+        return match self.mode {
+            ByRef => {
+                glue::drop_ty(bcx, self.val, self.ty);
+                zero_mem(bcx, self.val, self.ty);
+                return bcx;
+            }
+            ByValue => {
+                glue::drop_ty_immediate(bcx, self.val, self.ty);
+                zero_mem(bcx, self.val, self.ty);
+                return bcx;
+            }
+        };
+    }
+
     fn box_body(bcx: block) -> Datum {
         /*!
          *

src/rustc/middle/trans/expr.rs

@@ -573,7 +573,7 @@ fn trans_rvalue_dps_unadjusted(bcx: block, expr: @ast::expr,
             if bcx.expr_is_lval(a) {
                 let datum = unpack_datum!(bcx, trans_to_datum(bcx, a));
                 return match dest {
-                    Ignore => datum.drop_val(bcx),
+                    Ignore => datum.dropnzero_val(bcx),
                     SaveIn(addr) => datum.move_to(bcx, INIT, addr)
                 };
             } else {