C++ Modules Might Be Dead-on-Arrival (2019)(vector-of-bool.github.io)

    #include "file.h"

    // foo.cpp
    #include auto_generated_file.cpp

  // File "mymodule.ixx"
  module;

  #include <string>

  // declare interface
  export module mymodule;

  export namespace mymodule {
      // templates have to be declared
      // in interface to be known at
      // compile-time
      template<typename T>
      T add(T x, T y) {
          return x + y;
      }

      std::string greetings();
  }

  // implement interface
  module :private;

  std::string mymodule::greetings() {
      return "hello";
  }