[Bug libstdc++/67632] explicit instantiation omits copy constructor and others

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67632

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Not sure how it can be a libstdc++ issue, the copy constructor exists, the
library can't force the front-end to instantiate it.

I'm travelling without access to proper computers, but as far as I can tell
from coliru.stacked-crooked.com it links fine using clang++ -stdlib=libstdc++
(with libstdc++ 5.2.0).