[Bug c++/66635] g++ ICE when compiling constexpr code with comma operator

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66635

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Indeed, but the ICE was real and it's fixed for 5.4.0. I'm adding a testcase
and closing the bug.