[Bug c++/80829] Use of constexpr constructors with base type instantiation fails compilation

[neil.conway at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80829

--- Comment #2 from Neil Conway <neil.conway at gmail dot com> ---
Can anyone confirm this issue? In my opinion it is a significant regression in
GCC 7.x.