[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 #12 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It seems to have been fixed in 6.3.0

tmp$ ~/gcc/6.2.0/bin/g++ -E t.cc -o t.ii
tmp$ ~/gcc/6.2.0/bin/g++ -E x.cc -o x.ii
tmp$ ~/gcc/6.2.0/bin/g++ t.ii x.ii
/tmp/ccdXPlNS.o: In function `copy(std::unordered_map<int, int, std::hash<int>,
std::equal_to<int>, std::allocator<std::pair<int const, int> > > const&)':
x.cc:(.text+0x1f): undefined reference to `std::unordered_map<int, int,
std::hash<int>, std::equal_to<int>, std::allocator<std::pair<int const, int> >
>::unordered_map(std::unordered_map<int, int, std::hash<int>,
std::equal_to<int>, std::allocator<std::pair<int const, int> > > const&)'
collect2: error: ld returned 1 exit status
tmp$ ~/gcc/6.3.0/bin/g++ t.ii x.ii

I'll bisect it.