[Bug libstdc++/80448] #include fails with Clang 5.0

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80448

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
What are the following errors? I can't see why a default member initializer for
an enum can cause a problem.