https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69715
--- Comment #4 from Kip Warner <kip at thevertigo dot com> --- Hey Markus. I'm able to replicate your minimal with... $ g++ --version g++ (Ubuntu 5.2.1-22ubuntu2) 5.2.1 20151010 Well I'll be damned. It looks as though we've actually managed to find a bona fide bug.
