CMake 3.12: Transitive OBJECT Libraries issue

box.cc

#include "box.hh"

template class box<int>;

box.hh

#ifndef BOX_HH
#define BOX_HH 1

#include <utility>

template <class T> class box {
  T item_;

public:
  box(T t) : item_{std::move(t)} {}
  ~box() = default;

  T get() const { return item_; }
};

#endif

build.log

[ 75%] Linking CXX executable main
/zapps/cmake/3.12.0/gcc-7.3.0/bin/cmake -E cmake_link_script CMakeFiles/main.dir/link.txt --verbose=1
/apps/gcc/7.3.0/bin/c++  -g   CMakeFiles/main.dir/main.cc.o CMakeFiles/make_box.dir/make_box.cc.o  -o main
CMakeFiles/main.dir/main.cc.o: In function `main':
/fslhome/levijm/compute/cmake-3.12-issue/main.cc:9: undefined reference to `box<int>::get() const'
CMakeFiles/make_box.dir/make_box.cc.o: In function `make_box(int)':
/fslhome/levijm/compute/cmake-3.12-issue/make_box.cc:6: undefined reference to `box<int>::box(int)'
collect2: error: ld returned 1 exit status
make[2]: *** [main] Error 1

CMakeLists.txt

cmake_minimum_required(VERSION 3.12)
project(objectlib LANGUAGES CXX)

add_library(box OBJECT box.cc box.hh)
add_library(make_box OBJECT make_box.cc make_box.hh)
target_link_libraries(make_box PUBLIC box)

add_executable(main main.cc)
target_link_libraries(main PUBLIC make_box)

main.cc

#include "box.hh"
#include "make_box.hh"

extern template class box<int>;

int main() {
  box<int> b = make_box(0);

  return b.get();
}

make_box.cc

#include "make_box.hh"
#include "box.hh"

extern template class box<int>;

box<int> make_box(int i) { return box<int>{i}; }

make_box.hh

#ifndef MAKE_BOX_HH
#define MAKE_BOX_HH 1

#include "box.hh"

extern template class box<int>;

box<int> make_box(int i);

#endif