If in C# "Enum"s only accept whole types, why accept a "char"?

Question

When we’re learning about enums in C# is said to accept only integer numeric types. Therefore, we soon think of sbyte, byte, short, ushort, int, uint, long or ulong. But the code below also works, where we associate elements of enum to a guy char. Why does this happen?

public enum PayCode {
    NotPaid = 'N',
    Paid = 'P'
}

Answer 1

In fact the enum is using the type int and I can prove:

using static System.Console;
 
public class Program {
    public static void Main() {
        WriteLine(PayCode.NotPaid.GetTypeCode());
        WriteLine((int)(PayCode.NotPaid));
        WriteLine((char)(PayCode.NotPaid));
        Teste('A');
        int x = 'B';
    }
    public static void Teste(int x) {}
}
 
public enum PayCode {
    NotPaid = 'N',
    Paid = 'P'
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

So what happened? A promotion like char for a int. All char can be automatically considered as a numerical type larger than it, as the int if the site expects it. So, in addition to showing what is the internal type of the enum, used showing in other contexts where one expects int that send a char it’s okay.

This rule was defined by language. Is it correct? In other languages it was always easy to answer this because the type char actually it was just a number that by chance could be interpreted as if it were an ASCII table character. In C# it could be different since it has better abstractions, and has kind that was numerical and did not accept to convert automatically (bool), but they thought it best to keep the same semantics in this case.

And note that you can show the real value of the enumeration, if you really need to do this, saying how you want to show and works for both integer and character. But make no mistake, in memory you will have a saved integer where you have a value of that enumeration, as shown in the first line of the code.