* added _*coeffRef members in NestedByValue

* added ConjugateReturnType and AdjointReturnType that are type-defined to Derived&
  and Transpose<Derived> if the scalar type is not complex: this avoids abusive copies in
  the cache friendly Product

Eigen/src/Core/CwiseUnaryOp.h

@@ -143,10 +143,10 @@ MatrixBase<Derived>::cwiseAbs2() const
   *
   * \sa adjoint() */
 template<typename Derived>
-inline const CwiseUnaryOp<ei_scalar_conjugate_op<typename ei_traits<Derived>::Scalar>, Derived>
+inline const typename MatrixBase<Derived>::ConjugateReturnType
 MatrixBase<Derived>::conjugate() const
 {
-  return derived();
+  return ConjugateReturnType(derived());
 }
 
 /** \returns an expression of *this with the \a Scalar type casted to

Eigen/src/Core/MatrixBase.h

@@ -304,10 +304,17 @@ template<typename Derived> class MatrixBase
 
     Transpose<Derived> transpose();
     const Transpose<Derived> transpose() const;
-    const Transpose<
+
-      NestByValue<CwiseUnaryOp<ei_scalar_conjugate_op<typename ei_traits<Derived>::Scalar>, Derived> >
+    /** the return type of MatrixBase::conjugate() */
-    >
+    typedef typename ei_meta_if<NumTraits<Scalar>::IsComplex,
-    adjoint() const;
+                        CwiseUnaryOp<ei_scalar_conjugate_op<Scalar>, Derived>,
+                        Derived&
+                     >::ret ConjugateReturnType;
+    /** the return type of MatrixBase::adjoint() */
+    typedef Transpose<
+                NestByValue<typename ei_unref<ConjugateReturnType>::type>
+              > AdjointReturnType;
+    const AdjointReturnType adjoint() const;
     //@}
 
     /// \name Sub-matrices
@@ -465,7 +472,7 @@ template<typename Derived> class MatrixBase
 
     /// \name Coefficient-wise operations
     //@{
-    const CwiseUnaryOp<ei_scalar_conjugate_op<typename ei_traits<Derived>::Scalar>, Derived> conjugate() const;
+    const ConjugateReturnType conjugate() const;
 
     template<typename OtherDerived>
     const CwiseBinaryOp<ei_scalar_product_op<typename ei_traits<Derived>::Scalar>, Derived, OtherDerived>

Eigen/src/Core/NestByValue.h

@@ -71,12 +71,23 @@ template<typename ExpressionType> class NestByValue
       return m_expression.coeff(row, col);
     }
 
+    inline Scalar& _coeffRef(int row, int col)
+    {
+      return m_expression.const_cast_derived().coeffRef(row, col);
+    }
+
     template<int LoadMode>
     inline const PacketScalar _packetCoeff(int row, int col) const
     {
       return m_expression.template packetCoeff<LoadMode>(row, col);
     }
 
+    template<int LoadMode>
+    inline void _writePacketCoeff(int row, int col, const PacketScalar& x)
+    {
+      m_expression.const_cast_derived().template writePacketCoeff<LoadMode>(row, col, x);
+    }
+
   protected:
     const ExpressionType m_expression;
 };

Eigen/src/Core/Product.h

@@ -228,7 +228,7 @@ struct ei_traits<Product<Lhs, Rhs, EvalMode> >
     _LostBits = HereditaryBits & ~(
                 (_RowMajor ? 0 : RowMajorBit)
               | ((RowsAtCompileTime == Dynamic || ColsAtCompileTime == Dynamic) ? 0 : LargeBit)),
-    Flags = ((unsigned int)(LhsFlags | RhsFlags) & _LostBits)
+    Flags = ((unsigned int)(LhsFlags | RhsFlags) & _LostBits & ~NestedByValue)
           | EvalBeforeAssigningBit
           | EvalBeforeNestingBit
           | (_Vectorizable ? VectorizableBit : 0),

Eigen/src/Core/Transpose.h

@@ -125,9 +125,7 @@ MatrixBase<Derived>::transpose() const
   *
   * \sa transpose(), conjugate(), class Transpose, class ei_scalar_conjugate_op */
 template<typename Derived>
-inline const Transpose<
+inline const typename MatrixBase<Derived>::AdjointReturnType
-               NestByValue<CwiseUnaryOp<ei_scalar_conjugate_op<typename ei_traits<Derived>::Scalar>, Derived > >
-             >
 MatrixBase<Derived>::adjoint() const
 {
   return conjugate().nestByValue();