Added a comment to prevent placing an EIGEN_STRONG_INLINE where it makes no sense.

Eigen/src/Core/Product.h

@@ -419,6 +419,9 @@ template<> struct ei_gemv_selector<OnTheRight,RowMajor,false>
 /** \returns the matrix product of \c *this and \a other.
   *
   * \note If instead of the matrix product you want the coefficient-wise product, see Cwise::operator*().
+  * \note In MSVC, this function will not be inlined since ei_matrix_storage is an
+  *       unwindable object for dynamic matrices. Thus it does not help tagging
+  *       this function with EIGEN_STRONG_INLINE.
   *
   * \sa lazyProduct(), operator*=(const MatrixBase&), Cwise::operator*()
   */