polybar: GCC 7.1.0 Build Errors

Had no issue building with GCC 6.3.0, but I’m getting this error in the build process with GCC 7.1.0:

[ 13%] Building CXX object bin/CMakeFiles/polybar.dir/components/bar.cpp.o
cd /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5_build/bin && /usr/bin/x86_64-pc-linux-gnu-g++  -I/usr/include/cairo -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/libdrm -I/usr/include/libpng16 -I/usr/include/freetype2 -I/usr/include/alsa -I/var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/include -I/var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/lib/concurrentqueue/include -I/var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/lib/xpp/include   -DNDEBUG -march=native -O2 -pipe -Wall -Wextra -pedantic   -std=c++14 -o CMakeFiles/polybar.dir/components/bar.cpp.o -c /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/src/components/bar.cpp
In file included from /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/lib/xpp/include/xpp/proto/../generic.hpp:11:0,
                 from /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/lib/xpp/include/xpp/proto/x.hpp:9,
                 from /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/lib/xpp/include/xpp/event.hpp:9,
                 from /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/include/x11/types.hpp:3,
                 from /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/include/components/bar.hpp:12,
                 from /var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/src/components/bar.cpp:3:
/var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5/lib/xpp/include/xpp/proto/../generic/reply_iterator.hpp:89:11: error: specialization of ‘template<class Data, class> class xpp::generic::iterator<Connection, Object, xpp::generic::signature<void(XcbIterator*), Next>, xpp::generic::signature<int(const void*), (* & *(int (*)(const void*))SizeOf)>, xpp::generic::signature<XcbIterator(const Reply*), GetIterator> >::get<Data, <template-parameter-1-2> >’ must appear at namespace scope
     class get<xcb_str_t, Dummy>
           ^~~~~~~~~~~~~~~~~~~~~
make[2]: *** [bin/CMakeFiles/polybar.dir/build.make:183: bin/CMakeFiles/polybar.dir/components/bar.cpp.o] Error 1
make[2]: Leaving directory '/var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5_build'
make[1]: *** [CMakeFiles/Makefile2:494: bin/CMakeFiles/polybar.dir/all] Error 2
make[1]: Leaving directory '/var/tmp/portage/x11-misc/polybar-3.0.5/work/polybar-3.0.5_build'
make: *** [Makefile:130: all] Error 2