Add todo

compiler/NubLang/Generation/QBE/QBEGenerator.cs

@@ -294,6 +294,7 @@ public class QBEGenerator
         return size;
     }
 
+    // todo(nub31): EmitRValue should take a destination parameter so we can skip copying rvalues
     private void EmitCopyInto(ExpressionNode source, string destination)
     {
         if (source.Type.IsScalar)