Factor out the code to find gcc, and add a command-line option to override the default executable name. This should help cross-compilation by allowing a cross-gcc to be specified from the configuration file instead of only through the CC environment variable.

class A(T)
{
   void foo(void delegate (T) d) {}

   void bar()
   {
     foo(delegate void (T t) {});
   }
}

class B: A!(B) {}

class C: A!(C) {}