Please describe the problem:
Programs that use sigc::slot by #including <sigc++/slot.h> no longer compile with 2.2.  In 2.0, this file #included <sigc++/functors/slot.h>, so all the definitions in that file were available from slot.h

Steps to reproduce:
The following code compiles with 2.0 but not 2.2:

 ---- snip ----
#include <sigc++/slot.h>

int main(int argc, char **argv)
{
  sigc::slot<void, bool> s;

  return 0;
}
 ---- snip ----

Actual results:


Expected results:


Does this happen every time?


Other information: