I am not sure if this is a bug but the behavior is strange.

http://dpaste.dzfl.pl/c37e673f

module program;

import std.stdio;

struct S1 {
  int i;
  this (this) {
    writeln("S1 postblit");
  }
}

struct S2 {
  S1 v;
  C c1;
  this (S1 v) {
    this.v = v;
    this.c1 = new C(&this.f);
  }
  this (this) {
    writeln("S2 postblit");
    this.c1 = new C(&this.f);
  }
  S1 f () {
    return this.v;
  }
}

class C {
  S1 delegate () d;
  this (S1 delegate () d) {
    this.d = d;
  }
}

auto f (S1 v) {
  return S2(v);
}

void main () {
  auto s1 = f(S1(5));
  writeln(s1.c1.d().i, " == 5 ?");
}