[Bug c++/51707] [c++11] constexpr constructor cannot initialize const reference member

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51707

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
This is fixed in 4.9.0. I'm adding the testcase and closing the bug.