[Bug c++/59938] [C++11] Bogus "... is not a constant expression"

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59938

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
This is already fixed in mainline. I'm addding the testcase and closing the
bug.