...

Interestingly, this also happens with gcc by simply including <boost/function.hpp>.

I think I fixed this some time ago? Which Boost and which g++?

Sorry, you're right, I was trying with 1.40. With 1.42, it works.

...

I see there is a BOOST_NO_RTTI switch, does someone see a problem if I use it as a way to disable the features making use of any or function?

BOOST_NO_RTTI is the right switch for any, for function (before the fix) you'd have needed BOOST_NO_TYPEID. There is a difference on, for example, MSVC.

The switch is actually pretty cool and made my life way easier :) Richard, I just committed the fix in the trunk (https://svn.boost.org/svn/boost/trunk/boost/msm/back/state_machine.hpp), it should work now. Thanks, Christophe