https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67632
--- Comment #9 from Anthony Chuah <achuah at drwsg dot com> --- Forgot to add: this bug exists also for clang 5.0.0. % clang++ -std=c++11 --gcc-toolchain=/path/to/gcc t.o x.cc /tmp/x-063634.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+0x18): 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&)' clang-5.0: error: linker command failed with exit code 1 (use -v to see invocation)
