[Bug libstdc++/83981] vector::resize(size_type) should not require T to be CopyInsertable when std=c++14

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83981

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Also, if boost::optional had a noexcept move constructor it would work fine.
This is a boost bug.

The part of the patch addressing PR 83982 seems right.