To cast a negative value, you must enclose the value in parentheses
Values that you want to cast must be in parentheses.
The following sample generates CS0075:
using System; enum Myint : long { three = 3L, } class test { public static void Main(String [] args ) { Myint i = (Myint) -1 ; // CS0075 // try the following line instead // Myint i = (Myint) (-1) ; i++; } }