message: Bug in gcc-8
diff: @@ -18,8 +18,11 @@ namespace py=pybind11;
  template<class T, class=std::enable_if_t<std::is_integral<T>::value>>
  int getint(int i){return i;}
  -template<class T, class=decltype(std::declval<T>().template cast<int>())>
  -int getint(T i){return i.template cast<int>();}
  +// Gcc-8 has a bug that breaks this version, fixed in gcc-9
  +// template<class T, class=decltype(std::declval<T>().template cast<int>())>
  +// int getint(T i){return i.template cast<int>();}
  +template<class T>
  +auto getint(T i)->decltype(i.template cast<int>()){return i.template cast<int>();}
  // Raw clusters are clusters obtained through single-linkage, no merging.
  