C# - static types cannot be used as type arguments

Question

I've a generic class that helps me to do checks on argument values:

internal sealed class Argument<T>
    where T : class
{
    private void TraceAndThrow(Exception ex)
    {
        new InternalTraceHelper<T>().WriteError(ex);
        throw ex;
    }

    internal void ThrowNull(object value, string argName)
    {
        if (ReferenceEquals(value, null))
        {
            TraceAndThrow(new ArgumentNullException(argName));
        }
    }

    internal void ThrowIf(bool condition, string argName)
    {
        if (condition)
        {
            TraceAndThrow(new ArgumentException(null, argName));
        }
    }


    internal void ThrowNotInEnum(Type enumType, object value)
    {
        if (!Enum.IsDefined(enumType, value))
        {
            TraceAndThrow(new ArgumentOutOfRangeException(Resources.ArgEnumIllegalVal.InvariantFormat(value)));
        }
    }
}

But when I try to use it with a static class:

internal static class Class1
{
    private static Argument<Class1> _arg;
}

I got this error (at compilation):

static types cannot be used as type arguments

What am I doing wrong?

Answer 1

This is deliberate.

Static classes try to prevent inappropriate use, so in almost all situations, you can't use them in situations where you'd normally want an instance of the type... and that includes type arguments.

See section "Static classes" of the C# 6 spec for the very limited set of situations in which you can refer to static class types.