It looks like Martin Schulze will have libsigc 2.0 working with the SUN Forte compiler soon. That will allow gtkmm 2.4 to work with that compiler too. It has worked fine with gtkmm 2.0 and 2.2 for a while. As well as being a great signal/slot API, libsigc 2.0 is a hell of a C compiler test suite. It's a good thing we have gcc.
Damien Carbery at SUN has been _really_ helpful and patient with this. He must have tested at least 10 tarballs by now. As usual Martin Schulze is doing a great job of maintaining libsigc , and solving the more difficult problems.
SUN have offerered GNOME a SUN Box plus Forte compiler, but I don't think the GNOME sysadmins have figured out where to host it yet.
Update: I guess weblog-add.py does not like plus symbols in posts. You get to guess where they are missing.