.NET: Why aren't Enum's Range/Value Checked?

Question

This has always bugged me. Perhaps someone with some hardcore knowledge of .NET internals can explain it to me.

Suppose I define an enum as follows:

publ         


        

Answer 1

Range-checking has a potentially unnecessary cost. It's therefore reasonable to not perform it implicitly. As already mentioned, [Flags] require that no such checking takes place. If the runtime would check for the presence of [Flags], this would still incur a runtime penalty every time you perform a conversion.

The only way around this would be for the compiler to be aware of the [Flags] attribute. I guess this wasn't done to reduce the amount of runtime knowledge hardcoded into the compiler.