error::make_unique is not a member of ‘std’

Question

I am trying to compile the following thread pool program posted on code review to test it.

https://codereview.stackexchange.com/questions/55100/platform-independant-thread-pool-v4

But I am getting the errors

threadpool.hpp: In member function ‘std::future<decltype (task((forward<Args>)(args)...))> threadpool::enqueue_task(Func&&, Args&& ...)’:
threadpool.hpp:94:28: error: ‘make_unique’ was not declared in this scope
     auto package_ptr = make_unique<task_package_impl<R, decltype(bound_task)>>  (std::move(bound_task), std::move(promise));
                        ^
threadpool.hpp:94:81: error: expected primary-expression before ‘>’ token
     auto package_ptr = make_unique<task_package_impl<R, decltype(bound_task)>>(std::move(bound_task), std::move(promise));
                                                                             ^
main.cpp: In function ‘int main()’:
main.cpp:9:17: error: ‘make_unique’ is not a member of ‘std’
 auto ptr1 = std::make_unique<unsigned>();
             ^
main.cpp:9:34: error: expected primary-expression before ‘unsigned’
 auto ptr1 = std::make_unique<unsigned>();
                              ^
main.cpp:14:17: error: ‘make_unique’ is not a member of ‘std’
 auto ptr2 = std::make_unique<unsigned>();
             ^
main.cpp:14:34: error: expected primary-expression before ‘unsigned’
 auto ptr2 = std::make_unique<unsigned>();

Answer 1

1.gcc version >= 5
2.CXXFLAGS += -std=c++14
3. #include <memory>

Answer 2

If you have latest compiler, you can change the following in your build settings:

 C++ Language Dialect    C++14[-std=c++14]

This works for me.

Answer 3

make_unique is an upcoming C++14 feature and thus might not be available on your compiler, even if it is C++11 compliant.

You can however easily roll your own implementation:

template<typename T, typename... Args>
std::unique_ptr<T> make_unique(Args&&... args) {
    return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
}

(FYI, here is the final version of make_unique that was voted into C++14. This includes additional functions to cover arrays, but the general idea is still the same.)