This is another workaround for a libstdc++ problem. Both the g++ bug and libstdc++ use of it are fixed in 4.9.0, but present in the 4.8 series. So we can't remove it yet. I also verified, that when the hack is disabled, that g++ 4.9.0 gives the expected diagnostics about types not matching on the testcase Richard added for this hack.
So updating the comment with dates and version numbers..