Bug in type in error message.

[Martin v. Loewis]

> Moreover, I feel this should compile anyway - but that is another story ;)

On that story: No, it shouldn't. For dummy<0>,dummy<0>, the call is
indeed ambiguous; neither is dummy<0>,dummy<n> more special that
dummy<n>,dummy<0>, nor vice versa.

Adding

  double ch(dummy<0>, dummy<0>)
  {
    return 1;
  }

to your program makes it compile.

Regards,
Martin