gcc-7.2.0ではコンパイルエラーが発生していて、gcc-6.4.0ではコンパイルエラーのコードが必要です

Question

gcc-6.4.0で問題なくコンパイルして実行するコードがあります。

gcc-7.2.0/bin/g++ -std=c++14 myerr.cc 
myerr.cc: In lambda function: 
myerr.cc:53:52: error: binary expression in operand of fold-expression 
      tq_.push_back([&](){ return (dep->run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); }); 
myerr.cc:53:52: error: expected primary-expression before ‘,’ token 
      tq_.push_back([&](){ return (dep->run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); }); 
                ^
myerr.cc:53:58: error: expected primary-expression before ‘&&’ token 
      tq_.push_back([&](){ return (dep->run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); }); 
                  ^~ 
myerr.cc:53:52: error: binary expression in operand of fold-expression 
      tq_.push_back([&](){ return (dep->run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); }); 
              ~~~~~~~~~~^~~~~~ 
myerr.cc:53:63: error: mismatched operator in fold-expression before ‘>’ token 
      tq_.push_back([&](){ return (dep->run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); }); 
                 ^
myerr.cc:53:63: error: expected ‘)’ before ‘>’ token 

は、誰もが、エラーメッセージに助けてください： はしかし、GCC-7.2.0で、同じコードをコンパイルし、次のエラーを持っているでしょうか？コードは以下の通りです。

#include <iostream> 
#include <deque> 
#include <unordered_map> 
#include <vector> 
#include <utility> 
#include <memory> 
#include <functional> 

template <typename T> 
struct Task_Trait { 
    typedef T obj_t; 
    typedef T* obj_ptr; 

    using pfid_t = const char * (T::*)() const; 
    static pfid_t GetId; 
}; 


template <typename T> 
struct Task { 
    typedef Task<T> task_t; 
    typedef task_t * task_ptr; 
    typedef std::unordered_map<std::string, std::unique_ptr<task_t>> taskmap_t; 

private:  
    T * obj_; 
    std::vector<task_ptr> dependents_; 

    Task(T& obj) : obj_(&obj), dependents_() { 
    } 

    static taskmap_t gtaskmap_; 
    static std::deque<std::function<void()>> tq_; 

public: 
    static Task & CreateTask(T& obj) { 
     static const char * (T::*getId)() const = Task_Trait<T>::GetId; 
     const char * id = (obj.*getId)(); 
     auto it = gtaskmap_.find(id); 
     if (it == gtaskmap_.end()) { 
      it = gtaskmap_.emplace(id, std::move(std::unique_ptr<task_t>(new Task(obj)))).first; 
     } 
     return *(it->second); 
    } 

    template <typename F, class ... Args> 
    void run(F&& f, Args&& ... args) { 
     std::cout << "INFO: running function for task" << this->getId() << std::endl; 
     (this->obj_->*f)(std::forward<Args>(args)...); 
     for (auto dep : this->dependents_) { 
      //auto mfunc = &(Task<T>::run<P>); 
      tq_.push_back([&](){ return (dep->run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); }); 
     } 
     while (!tq_.empty()) { 
      std::function<void()> task = std::move(this->tq_.front()); 
      this->tq_.pop_front(); 
      task(); 
     } 
    } 

    const char * getId() const { 
     static typename Task_Trait<T>::pfid_t getId = Task_Trait<T>::GetId; 
     return (this->obj_->*getId)(); 
    } 

    void depend(const char * id) { 
     static typename Task_Trait<T>::pfid_t getId = Task_Trait<T>::GetId; 
     auto dit = gtaskmap_.find(id); 
     if (dit != gtaskmap_.end()) { 
      dependents_.push_back(dit->second.get()); 
      std::cout << "INFO: " << id << " depends on " << this->getId() << std::endl; 
     } else { 
      std::cout << "ERROR: cannot find dependent " << id << " for task " << this->getId() << std::endl; 
     } 
    } 
}; 


class DataTask { 
public: 
    DataTask(const char * id) : id_(id) { 
    } 

    void print(int x) { 
     std::cout << "id=" << id_ << " value=" << x << std::endl; 
    } 

    const char * id() const { 
     return id_.c_str(); 
    } 

private: 
    std::string id_; 
}; 

template <typename T> 
typename Task<T>::taskmap_t Task<T>::gtaskmap_; 

template <typename T> 
typename std::deque<std::function<void()>> Task<T>::tq_; 

template <> 
Task_Trait<DataTask>::pfid_t Task_Trait<DataTask>::GetId = &DataTask::id; 

int main() { 
    DataTask a("a"); 
    DataTask b("b"); 
    DataTask c("c"); 
    DataTask d("d"); 
    DataTask e("e"); 

    auto & ta = Task<DataTask>::CreateTask(a); 
    auto & tb = Task<DataTask>::CreateTask(b); 
    auto & tc = Task<DataTask>::CreateTask(c); 
    auto & td = Task<DataTask>::CreateTask(d); 
    auto & te = Task<DataTask>::CreateTask(e); 

    ta.depend("b"); 
    ta.depend("c"); 
    tb.depend("d"); 
    tb.depend("e"); 

    return 0; 
} 

Answer 1

（run()前）run()でtemplateを追加してみてください。

私は、リンクされた問題の答えを読む

// ...............................vvvvvvvvv 
tq_.push_back([&](){ return (dep->template run<F, Args&&...>)(std::forward<F>(f), std::forward<Args>(args)...); });