[Bug c++/55425] constexpr does not work in many situations (both built-in and user supplied literals)

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55425

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I think we can close this. The __func__ snippet now works in mainline with
-std=c++14, I'm adding it to the testsuite.