Fixed an error introduced in commit 83c8fef.

Author: justusc

src/TiledArray/dist_eval/array_eval.h

@@ -200,7 +200,9 @@ namespace TiledArray {
       /// This function handles the cleanup for tiles that are not needed in
       /// subsequent computation.
       /// \param i The index of the tile
-      virtual void discard_tile(size_type i) const { }
+      virtual void discard_tile(size_type) const {
+        const_cast<ArrayEvalImpl_*>(this)->notify();
+      }
 
     private: