diff --git a/Eigen/src/SparseCore/SparseCwiseBinaryOp.h b/Eigen/src/SparseCore/SparseCwiseBinaryOp.h
index 5080292b8..22c227edd 100644
--- a/Eigen/src/SparseCore/SparseCwiseBinaryOp.h
+++ b/Eigen/src/SparseCore/SparseCwiseBinaryOp.h
@@ -63,6 +63,7 @@ class CwiseBinaryOpImpl<BinaryOp, Lhs, Rhs, Sparse>
 {
   public:
     class InnerIterator;
+    class ReverseInnerIterator;
     typedef CwiseBinaryOp<BinaryOp, Lhs, Rhs> Derived;
     EIGEN_SPARSE_PUBLIC_INTERFACE(Derived)
     CwiseBinaryOpImpl()
diff --git a/Eigen/src/SparseCore/TriangularSolver.h b/Eigen/src/SparseCore/TriangularSolver.h
index 8ed471e45..7f27df726 100644
--- a/Eigen/src/SparseCore/TriangularSolver.h
+++ b/Eigen/src/SparseCore/TriangularSolver.h
@@ -156,6 +156,7 @@ struct sparse_solve_triangular_selector<Lhs,Rhs,Mode,Upper,ColMajor>
         {
           if(!(Mode & UnitDiag))
           {
+            // TODO replace this by a binary search. make sure the binary search is safe for partially sorted elements
             typename Lhs::ReverseInnerIterator it(lhs, i);
             while(it && it.index()!=i)
               --it;