AMDG

And what is wrong with leaving bind in the boost namespace as I was
suggesting and define boost::function like this:

  namespace boost {
    namespace function_adl_block {
      template<class Sig>
      struct function {...};
    }
    using function_adl_block::function;
  }

Now the "boost" namespace is no longer associated with boost::function,
and boost::bind won't be found by ADL. Unless I'm mistaken, and a quick
test with comeauonline suggests I'm not. But Steven and Peter are
usually right about this stuff, so I'll patiently wait to be corrected
and learn. :-)

Yes, you're correct about this.