Best exception for an invalid generic type argument

Question

I\'m currently writing some code for UnconstrainedMelody which has generic methods to do with enums.

Now, I have a static class with a bunch of methods which are

Answer 1

I'm always wary of writing custom exceptions, purely on the grounds that they aren't always documented clearly and cause confusion if not named correctly.

In this case I would throw an ArgumentException for the flags check failure. It's all down to preference really. Some coding standards I've seen go as far as to define which types of exceptions should be thrown in scenarios like this.

If the user was trying to pass in something which wasn't an enum then I would throw an InvalidOperationException.

Edit:

The others raise an interesting point that this is not supported. My only concern with a NotSupportedException is that generally those are the exceptions that get thrown when "dark matter" has been introduced to the system, or to put it another way, "This method must go into the system on this interface, but we won't turn it on until version 2.4"

I've also seen NotSupportedExceptions be thrown as a licensing exception "you're running the free version of this software, this function is not supported".

Edit 2:

Another possible one:

System.ComponentModel.InvalidEnumArgumentException  

The exception thrown when using invalid arguments that are enumerators.