Avoid including <sstream> with EIGEN_NO_IO

Eigen/src/SparseCore/SparseMatrix.h

@@ -786,6 +786,7 @@ class SparseMatrix
     template<typename OtherDerived>
     EIGEN_DONT_INLINE SparseMatrix& operator=(const SparseMatrixBase<OtherDerived>& other);
 
+#ifndef EIGEN_NO_IO
     friend std::ostream & operator << (std::ostream & s, const SparseMatrix& m)
     {
       EIGEN_DBG_SPARSE(
@@ -830,6 +831,7 @@ class SparseMatrix
       s << static_cast<const SparseMatrixBase<SparseMatrix>&>(m);
       return s;
     }
+#endif
 
     /** Destructor */
     inline ~SparseMatrix()

Eigen/src/SparseCore/SparseMatrixBase.h

@@ -214,7 +214,7 @@ template<typename Derived> class SparseMatrixBase
     inline void assignGeneric(const OtherDerived& other);
 
   public:
-
+#ifndef EIGEN_NO_IO
     friend std::ostream & operator << (std::ostream & s, const SparseMatrixBase& m)
     {
       typedef typename Derived::Nested Nested;
@@ -263,6 +263,7 @@ template<typename Derived> class SparseMatrixBase
       }
       return s;
     }
+#endif
 
     template<typename OtherDerived>
     Derived& operator+=(const SparseMatrixBase<OtherDerived>& other);

Eigen/src/SparseCore/SparseVector.h

@@ -353,6 +353,7 @@ class SparseVector
     }
     #endif
 
+#ifndef EIGEN_NO_IO
     friend std::ostream & operator << (std::ostream & s, const SparseVector& m)
     {
       for (Index i=0; i<m.nonZeros(); ++i)
@@ -360,6 +361,7 @@ class SparseVector
       s << std::endl;
       return s;
     }
+#endif
 
     /** Destructor */
     inline ~SparseVector() {}