3187 – Nested foreach over opApply doesn't work

Calling nested foreach statements on types that implement opApply causes an error. There appears to be a bug in the code generated by the compiler.
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
This is the code DMD generates for the testForeach method, with the problem line highlighted:
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;
}
This problem occurs with both DMD 1.x and 2.x compilers.

I'm changing this from wrong-code to ICE, since it never reaches code generation.

(In reply to comment #1)
> I'm changing this from wrong-code to ICE, since it never reaches code
> generation.
Actually although the compiler fouls this up badly, it isn't an ICE. It's a rejects-valid with a really bad diagnostic.

https://github.com/D-Programming-Language/dmd/pull/546 

https://github.com/D-Programming-Language/dmd/commit/514e1fa711a5774bf7c393772cd8489b2af2534e
https://github.com/D-Programming-Language/dmd/commit/d124949381400582b5d6a6c5015bf42483afa54d 

*** Issue 2192 has been marked as a duplicate of this issue. ***