How to pass arguments to ASTFrontendAction

Question

Is there a way I can pass constructor arguments to classes inheriting from clang::ASTFrontendAction in programs based on libtooling? All examples I have found online look something like this:

int main() {
    ClangTool Tool(...);

    return Tool.run(newFrontendActionFactory<SomeFrontendAction>().get());
}

But what if SomeFrontendAction needs to be aware of, i.e. options passed in by the tools user? How can I pass those on to the constructor of SomeFrontendAction?

Answer 1

I found this answer while looking for an answer to this question. You should create your own version of newFrontEndActionFactory. The original code for newFrontEndActionFactory is:

template <typename T>
std::unique_ptr<FrontendActionFactory> newFrontendActionFactory() {
  class SimpleFrontendActionFactory : public FrontendActionFactory {
   public:
    std::unique_ptr<FrontendAction> create() override {
      return std::make_unique<T>();
    }
  };
 
  return std::unique_ptr<FrontendActionFactory>(
      new SimpleFrontendActionFactory);
}

I replaced T with SomeFrontendAction, added a constructor to class SimpleFrontendActionFactory and then pass the options to SomeFrontendAction. The resulting function looks something like this:

std::unique_ptr<FrontendActionFactory> myNewFrontendActionFactory(string options) {
  class SimpleFrontendActionFactory : public FrontendActionFactory {
   public:
    SimpleFrontendActionFactory(string options) : mOptions(options) {}

    std::unique_ptr<FrontendAction> create() override {
      return std::make_unique<SomeFrontendAction>(options);
    }

   private:
    string mOptions;
  };
 
  return std::unique_ptr<FrontendActionFactory>(
      new SimpleFrontendActionFactory(options));
}

int main() {
  ClangTool Tool(...);

  return Tool.run(myNewFrontendActionFactory(options).get());
}