// clang++ -std=c++14 -O0 -g -Wall -fcolor-diagnostics main.cpp

#include <string>

template <int tag> class string_wrapper final {
public:
  explicit string_wrapper(std::string str) : value_(std::move(str)) {}

  const std::string &str() const noexcept { return value_; }

private:
  std::string value_;
};

enum type_tags { a, b, c };
using type_a = string_wrapper<a>;
using type_b = string_wrapper<b>;
using type_c = string_wrapper<c>;

int main() {
  auto some_a = type_a("some a");
  auto some_b = type_b("some b");
  auto some_c = type_c("some c");

  some_a = some_c; // Does not compile! Check error message

  return 0;
}