[DMD 0.106]

Looks like anonymous delegates are always type of first template instantiation:

dgbug.d(11): function dgbug.A!(C ).A.foo (void delegate(C )d) does not match argument types (void delegate(B ))
dgbug.d(11): cannot implicitly convert expression __funclit1 of type void delegate(B ) to void delegate(C )

<dgbug.d>
class A(T)
{
  void foo(void delegate (T) d) {}

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

class B: A!(B) {}

class C: A!(C) {}

void main()
{
}