Instantiating template classes with default template arguments

[janderson]

Sean Kelly wrote:
> 
> Sean
> 
> P.S. In writing this, I discovered that the following code compiles when 
> it should not:
> 
>     class C( T = int, U = int ) {}
>     class C( T = int, U : char = int ) {}
> 
>     void main()
>     {
>         auto c = new C!(int);
>     }

It looks like the compiler doesn't evaluate the template until its used. 
  I'm down with that.