Comment 7 for bug 1279029

There is nothing magical going on an this is indeed a (pretty) well known bug: essentially boost introduced some move constructors, but did not properly define their copy constructors. Early gcc violated the c++11 standard and compiled the code just fine, later gcc did implement the standard correctly and refuses to compile the boost code. So it is a nice interlock between a bug in boost and a bug in gcc. Further reading: http://stackoverflow.com/questions/10440860/boost-intrusive-unordered-set-broken-in-1-48-with-gcc-in-c11-mode