'constructor' : structs cannot call base class constructors
A struct cannot call a base class constructor; remove the call to the base class constructor.
The following sample generates CS0522:
namespace x { public class clx { public clx(int i) { } public static void Main() { } } public struct cly { public cly(int i):base(0) // CS0522 // try the following line instead // public cly(int i){} { } } }