amazing function behavior

[Zarathustra]

Oh, I just find out cause of this behaviour in other module I had:
extern (Windows) alias dword function() Tfunc1;
extern (Windows) alias dword function(wstr) Tfunc2;
const Tfunc2 func2;
static this(){
  func2 = cast(Tfunc1)0x0; // for DMD2 It is not error!!!
                           // but it doesn't has a sens!!!
}