This is a result of an update I made to Boost PP for VC++ to handle possibly "empty" tuples, which fixes a corner case error in the VC++ non-standard conforming preprocessor. The warning is benign, but I have found no way to turn it off at the Boost PP level.
A possible workaround for the next release, which I will try, is to duplicate BOOST_PP_EXPAND under a different internal name and use that duplicated macro internally and see if I can turn off the warning there. Unfortunately if I surround the invocation of the currently internal use of BOOST_PP_EXPAND with the appropriate #pragma to disable the warning VC++ ignores it.
Thanks Edward. At least I know it's not in our code. So I assume that for now it's best to disable the warning at the top level if we want to get rid of it. Cheers, Filip