Resolve tagging issue in PassiveAssign

Author: joshkellyjak

Common/include/basic_types/datatype_structure.hpp

@@ -89,8 +89,13 @@ void SetDerivative(su2double& data, const passivedouble& val);
 
 FORCEINLINE void SetValue(su2double& data, const passivedouble& val) { data.setValue(val); }
 
+FORCEINLINE passivedouble GetValue(const &double data) { return data; }
+
 FORCEINLINE passivedouble GetValue(const su2double& data) { return data.getValue(); }
 
+template<typename Expr>
+FORCEINLINE passivedouble GetValue(const codi::ExpressionInterface<double, Expr>& data) { return data.cast().getValue(); }
+
 FORCEINLINE void SetSecondary(su2double& data, const passivedouble& val) { data.setGradient(val); }
 
 FORCEINLINE void SetDerivative(su2double& data, const passivedouble& val) { data.setGradient(val); }