UDAs and no complaints about "need 'this'"

[jkpl via Digitalmars-d]

On Thursday, 9 April 2015 at 09:53:15 UTC, John Colvin wrote:
> struct BigLongStructName
> {
> 	int evenLongerMemberName;
> }
>
> struct QN{}
>
> unittest
> {
> 	BigLongStructName bigLongStructName;
>
> 	@(bigLongStructName.evenLongerMemberName)
> 		QN quickName;
> 	
> 	__traits(getAttributes, quickName)[0]++;
> }
>
> Is it just me or is it weird that this works? Once you pull the 
> UDA out from being a storage class and attempt to alias it, you 
> get the usual "need 'this' for 'evenLongerMemberName' of type 
> 'int'" error messages on use.
>
> Why are UDAs so special? I don't believe there's any other way 
> to achieve this sort of effective renaming.

I think it's an error. When the attribute is a struct, it looks 
like the member is processed as a static variable. But the 
equivalent with a class raises an AV:

---
class BigLongStructName
{
	int evenLongerMemberName;
}

struct QN{}

unittest
{
     import std.stdio;

	BigLongStructName bigLongStructName;

	@(bigLongStructName.evenLongerMemberName)
		QN quickName;
	
	__traits(getAttributes, quickName)[0]++;
}
---

which is a totally expected behaviour.