What we'd like to do is to test whether some very mildly breaking changes to
are so mild as to affect no users, and on that basis propose WG21 to make those mildly breaking changes to in the next C++ standard. And to test this, we'd like to modify Boost.System with those mildly breaking changes, ship a release and see how many users complain. If it is zero, we have evidence for WG21 that this is not a consequential change. The usual way is to announce the upcoming change in release nnn and then make the change in release nnn + 1. What is wrong with using this method in your case, if all parties are in agreement to do it ?
It goes without saying that this forthcoming change would be announced one release ahead as per Boost custom. So, next release would have it #ifdef'd off by default, following release #ifdef's it on by default. A macro would allow users to select which implementation. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/