__traits(allMembers) and aliases

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On Tuesday, 25 August 2015 at 12:06:08 UTC, Mike Parker wrote:
> Is there a way to determine whether a given symbol is an alias? 
> Consider this:
>
> ```
> module funcs;
> alias FuncPtr = void function();
> @ChooseMe FuncPtr funcPtr;
> alias anotherName = funcPtr;
> ```
>
> Handing this module off to __traits(allMembers), then checking 
> for the UDA on each member, I can filter out FuncPtr just fine. 
> Unfortunately, anotherName passes the test, but I don't want it 
> to. Is there anyway I can distinguish the anotherName alias 
> from funcPtr without tagging it with a UDA? I can't find any 
> sort of isAlias trait anywhere.

I've been doing work on this recently. As far as I can tell, 
there is no way to do this. The problem is that an alias behaves 
exactly like the thing being aliased since it's just a name 
replacement, so there are no giveaways like being unable to take 
its address like enums. Aliases are more or less invisible. 
Hence, having an isAlias trait would be a really good idea.