custom attribute proposal (yeah, another one)

[Piotr Szturmaj]

Jacob Carlborg wrote:
> On 2012-04-07 00:40, Piotr Szturmaj wrote:
>
>> Ok, but it needs more work in the compiler, comparing to identifier
>> search and remembering expression tuple of a symbol. Also, I just found
>> a major drawback of this approach: consider parameterless attributes
>> like @NotNull. What would you return from function named NotNull()?
>
> void ?

I know that's the answer, but how would you store void, and get it from 
__traits(getAttributes) ?