From bc065c75d2a8df928cb368d0352b8fcb25791fa8 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Mon, 1 Sep 2014 14:50:59 +0200
Subject: [PATCH] Implement the missing bits to make Solve compatible with
 sparse rhs

---
 Eigen/src/Core/Solve.h              |  9 +++++++++
 Eigen/src/SparseCore/SparseAssign.h | 12 ++++++++++++
 Eigen/src/SparseCore/SparseUtil.h   |  8 ++++++++
 3 files changed, 29 insertions(+)

diff --git a/Eigen/src/Core/Solve.h b/Eigen/src/Core/Solve.h
index c28789968..a1501c259 100644
--- a/Eigen/src/Core/Solve.h
+++ b/Eigen/src/Core/Solve.h
@@ -99,6 +99,15 @@ private:
   Scalar coeff(Index i) const;
 };
 
+#ifdef EIGEN_TEST_EVALUATORS
+// Generic API dispatcher
+template<typename Decomposition, typename RhsType, typename StorageKind>
+class SolveImpl : public internal::generic_xpr_base<Solve<Decomposition,RhsType>, MatrixXpr, StorageKind>::type
+{
+  public:
+    typedef typename internal::generic_xpr_base<Solve<Decomposition,RhsType>, MatrixXpr, StorageKind>::type Base;
+};
+#endif
 
 namespace internal {
 
diff --git a/Eigen/src/SparseCore/SparseAssign.h b/Eigen/src/SparseCore/SparseAssign.h
index 0a29cb32f..36c9fe845 100644
--- a/Eigen/src/SparseCore/SparseAssign.h
+++ b/Eigen/src/SparseCore/SparseAssign.h
@@ -284,6 +284,18 @@ struct Assignment<DstXprType, SrcXprType, internal::assign_op<typename DstXprTyp
   }
 };
 
+// Specialization for "dst = dec.solve(rhs)"
+// NOTE we need to specialize it for Sparse2Sparse to avoid ambiguous specialization error
+template<typename DstXprType, typename DecType, typename RhsType, typename Scalar>
+struct Assignment<DstXprType, Solve<DecType,RhsType>, internal::assign_op<Scalar>, Sparse2Sparse, Scalar>
+{
+  typedef Solve<DecType,RhsType> SrcXprType;
+  static void run(DstXprType &dst, const SrcXprType &src, const internal::assign_op<Scalar> &)
+  {
+    src.dec()._solve_impl(src.rhs(), dst);
+  }
+};
+
 } // end namespace internal
 
 #endif // EIGEN_TEST_EVALUATORS
diff --git a/Eigen/src/SparseCore/SparseUtil.h b/Eigen/src/SparseCore/SparseUtil.h
index 0183907a1..28bf89bca 100644
--- a/Eigen/src/SparseCore/SparseUtil.h
+++ b/Eigen/src/SparseCore/SparseUtil.h
@@ -156,6 +156,14 @@ template<typename T> struct plain_matrix_type<T,Sparse>
     typedef SparseMatrix<_Scalar, _Options, _Index> type;
 };
 
+#ifdef EIGEN_TEST_EVALUATORS
+template<typename Decomposition, typename RhsType>
+struct solve_traits<Decomposition,RhsType,Sparse>
+{
+  typedef typename sparse_eval<RhsType, RhsType::RowsAtCompileTime, RhsType::ColsAtCompileTime>::type PlainObject;
+};
+#endif
+
 template<typename Derived>
 struct generic_xpr_base<Derived, MatrixXpr, Sparse>
 {