C# 7.3 Enum constraint: Why can't I use the nullable enum?

Question

Now that we have enum constraint, why doesn\'t compiler allow me to write this code?

public static TResult? ToEnum(this String value, TResult?         


        

Answer 1

You can, but you have to add another constraint: the struct constraint.

public static void DoSomething(T? defaultValue) where T : struct, Enum
{
}