Fallback Reshaped to MapBase when possible (same storage order and linear access to the nested expression)

Eigen/src/Core/util/IntegralConstant.h

@@ -265,6 +265,11 @@ static const auto fix(int val);
 
 #endif // EIGEN_PARSED_BY_DOXYGEN
 
+const int AutoOrderValue = 2;
+const internal::FixedInt<ColMajor>        ColOrder;
+const internal::FixedInt<RowMajor>        RowOrder;
+const internal::FixedInt<AutoOrderValue>  AutoOrder;
+
 } // end namespace Eigen
 
 #endif // EIGEN_INTEGRAL_CONSTANT_H