4 fail_compilation/ice14130.d(10): Error: undefined identifier `Undef`
5 fail_compilation/ice14130.d(14): Error: template `ice14130.foo` cannot deduce function from argument types `!()(int)`
6 fail_compilation/ice14130.d(10): Candidate is: `foo(R, F = Undef)(R r, F s = 0)`
10 F foo(R, F = Undef)(R r, F s = 0) {}