Using getSymbolsByUDA in a static foreach loop

[Jack Stouffer]

On Wednesday, 19 January 2022 at 21:49:12 UTC, Adam D Ruppe wrote:
> I never use most of std.traits, they just complicate things. 
> Bleh idk, I wouldn't bother with it and loop through the 
> __traits instead.

Unless I'm missing something obvious this has to be a DMD bug, 
because this prints nothing:

```d
import std.traits;
import std.stdio;

enum Runnable;

struct SubSystem
{
         void run()
         {
         	writeln("SubSystem ran");
         }
}

struct Manager
{
         @Runnable SubSystem subsystem;

         void run()
         {
             static foreach(member; __traits(allMembers, Manager))
             {
                 static foreach (attribute; 
__traits(getAttributes, member))
                 {
                     static if (attribute == Runnable)
                     {
                         __traits(child, Manager, member).run();
                     }
                 }
             }
         }
}

void main()
{
         Manager m;
         m.run();
}
```

The `__traits(getAttributes, member)` call always returns an 
empty tuple. Calling `__traits(getAttributes, Manager.subsystem)` 
manually works as expected.