Nested Foreach

[Ary Borenszweig]

John C escribió:
> Is nesting foreach statements supposed to work? I hit a problem today that I've never encountered before, even though I'm sure I've nested foreach before. Here's an example that illustrates the problem:
> 
> 
> class Collection {
> 
>   int opApply(int delegate(ref Object) a) {
>     return 0;
>   }
> 
> }
> 
> Object testForeach(Collection level1, Collection level2) {
>   foreach (first; level1) {
>     foreach (second; level2) {
>       return second;
>     }
>   }
>   return null;
> }
> 
> void main() {
>   testForeach(new Collection, new Collection);
> }
> 
> Error: cannot implicitly convert expression (second) of type object.Object to int
> 
> If someone else can repro this, I'll enter it into Bugzilla.
> 
> John.

I can confirm that it's a bug. And I can see in Descent the testForeach 
function is translated to this:

Object testForeach(Collection level1, Collection level2) {
   switch(level1.opApply(delegate (Object __applyArg0) {
     {
       Object first = __applyArg0;
       switch(level2.opApply(delegate (Object __applyArg0) {
         {
           Object second = __applyArg0;
           {
             // ** Here's the problem **
             __result = cast(Object) cast(int) second;
             return 2;
           }
         }
         return 0;
       } )) {
         default:
         break;
         case 2:
           __result = __result;
           return 2;
       }
     }
     return 0;
   } )) {
     default:
     break;
     case 2:
       return __result;
   }
   return cast(Object) null;
}

Maybe that helps fixing it. :-)