http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48224
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-03-21 19:29:44 UTC --- The C++ standard library says the effects are undefined if an incomplete type is used as a template argument when instantiating a template component (17.4.3.6p2)
