http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52136
--- Comment #4 from Sylvestre Ledru <sylvestre at debian dot org> 2012-02-06 14:08:21 UTC --- I found this bug (or behavior) while playing with clang. I am not really sure to understand why friend class should impact his parent but if g++ respects the standard, why not...