use delegate with IUnknown

[Long Chang]

I compile this code got error....

   1. interface IUnknown{}  
   2. class klass : IUnknown{   
   3.     this(){}      
   4.     void add(void delegate() dg){}  
   5. }  
   6. void main(){  
   7.     auto t  = new klass;      
   8.     t.add(delegate void(){});     
   9. }  

t2.d(8): function t2.klass.add (void delegate()) does not match parameter types (void delegate())
t2.d(8): Error: cannot implicitly convert expression (__dgliteral1) of type void delegate() to void delegate() 


this code work fine.
   1. interface IUnknown_{}  
   2. class klass : IUnknown_{   
   3.     this(){}      
   4.     void add(void delegate() dg){}  
   5. }  
   6. void main(){  
   7.     auto t  = new klass;      
   8.     t.add(delegate void(){});     
   9. }  

	
Is this a bug?