resurrected sparse triangular solver

Eigen/src/Core/Flagged.h

@@ -62,6 +62,7 @@ template<typename ExpressionType, unsigned int Added, unsigned int Removed> clas
     EIGEN_GENERIC_PUBLIC_INTERFACE(Flagged)
     typedef typename ei_meta_if<ei_must_nest_by_value<ExpressionType>::ret,
         ExpressionType, const ExpressionType&>::ret ExpressionTypeNested;
+    typedef typename ExpressionType::InnerIterator InnerIterator;
 
     inline Flagged(const ExpressionType& matrix) : m_matrix(matrix) {}
 

Eigen/src/Core/SolveTriangular.h

@@ -35,7 +35,7 @@ template<typename Lhs, typename Rhs,
                      ? Upper
                      : -1,
   int StorageOrder = ei_is_part<Lhs>::value ? -1  // this is to solve ambiguous specializations
-                   : int(Lhs::Flags) & RowMajorBit ? RowMajor : ColMajor
+                   : int(Lhs::Flags) & (RowMajorBit|SparseBit)
   >
 struct ei_solve_triangular_selector;
 
@@ -51,7 +51,7 @@ struct ei_solve_triangular_selector<Part<Lhs,LhsMode>,Rhs,UpLo,StorageOrder>
 
 // forward substitution, row-major
 template<typename Lhs, typename Rhs, int UpLo>
-struct ei_solve_triangular_selector<Lhs,Rhs,UpLo,RowMajor>
+struct ei_solve_triangular_selector<Lhs,Rhs,UpLo,RowMajor|IsDense>
 {
   typedef typename Rhs::Scalar Scalar;
   static void run(const Lhs& lhs, Rhs& other)
@@ -138,7 +138,7 @@ struct ei_solve_triangular_selector<Lhs,Rhs,UpLo,RowMajor>
 //  - inv(Upper,         ColMajor) * Column vector
 //  - inv(Upper,UnitDiag,ColMajor) * Column vector
 template<typename Lhs, typename Rhs, int UpLo>
-struct ei_solve_triangular_selector<Lhs,Rhs,UpLo,ColMajor>
+struct ei_solve_triangular_selector<Lhs,Rhs,UpLo,ColMajor|IsDense>
 {
   typedef typename Rhs::Scalar Scalar;
   typedef typename ei_packet_traits<Scalar>::type Packet;

Eigen/src/Core/util/Constants.h

@@ -199,20 +199,16 @@ enum {
   NoUnrolling
 };
 
-enum {
-  Dense   = 0,
-  Sparse  = SparseBit
-};
-
 enum {
   ColMajor = 0,
   RowMajor = RowMajorBit
 };
 
 enum {
-  NoDirectAccess = 0,
+  IsDense         = 0,
+  NoDirectAccess  = 0,
   HasDirectAccess = DirectAccessBit,
-  IsSparse = SparseBit
+  IsSparse        = SparseBit
 };
 
 const int FullyCoherentAccessPattern  = 0x1;

Eigen/src/Core/util/XprHelper.h

@@ -110,7 +110,7 @@ template<int _Rows, int _Cols> struct ei_size_at_compile_time
 
 template<typename T, int Sparseness = ei_traits<T>::Flags&SparseBit> class ei_eval;
 
-template<typename T> struct ei_eval<T,Dense>
+template<typename T> struct ei_eval<T,IsDense>
 {
   typedef Matrix<typename ei_traits<T>::Scalar,
                 ei_traits<T>::RowsAtCompileTime,