template forward reference

[Sean Kelly]

C. Dunn wrote:
> This works:
> <code>
> class Foo(T){
>   int bar(){
>     return A.hi();
>   }
> };
> 
> class A{
>   static int hi(){
>     return 0;
>   }
> 
>   F!(char) x;
> };
> </code>
> 
> But if I split these into 2 separate modules, where each module imports the other, then the module with class A does not compile:
>   Error: forward reference to 'Foo!(char)'
>   Error: F is used as a type
> 
> If I make the template class a regular class, it compiles fine.  I understand that cyclic template specializations could create problems, but I don't see why moving a template into a separate module fails.  This works easily in C++ by just forward-declaring class A.

Right.  And forward declarations are impossible in D because a type's 
name includes the module in which it is declared.

> Why does this not work?  Are there plans to support it in the future?

It looks like a compiler bug to me, though who knows when it will be 
addressed.


Sean