C++ error::make_unique 不是“std”的成员
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error::make_unique is not a member of ‘std’
提问by Ali786
I am trying to compile the following thread pool program posted on code review to test it.
我正在尝试编译发布在代码上的以下线程池程序来测试它。
https://codereview.stackexchange.com/questions/55100/platform-independant-thread-pool-v4
https://codereview.stackexchange.com/questions/55100/platform-independant-thread-pool-v4
But I am getting the errors
但我收到了错误
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>();
回答by ComicSansMS
make_uniqueis an upcoming C++14 featureand thus might not be available on your compiler, even if it is C++11 compliant.
make_unique是即将推出的 C++14 功能，因此可能无法在您的编译器上使用，即使它符合 C++11。
You can however easily roll your own implementation:
但是，您可以轻松推出自己的实现：
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_uniquethat was voted into C++14. This includes additional functions to cover arrays, but the general idea is still the same.)
（仅供参考，这里是make_unique投票到 C++14的最终版本。这包括覆盖数组的附加功能，但总体思路仍然相同。）
回答by Anil8753
If you have latest compiler, you can change the following in your build settings:
如果您有最新的编译器，则可以在构建设置中更改以下内容：
C++ Language Dialect C++14[-std=c++14]
This works for me.
这对我有用。
回答by Jagger Yu
1.gcc version >= 5
2.CXXFLAGS += -std=c++14
3. #include <memory>
1.gcc 版本 >= 5
2.CXXFLAGS += -std=c++14
3. #include <memory>
回答by kovac
This happens to me while working with XCode (I'm using the most current version of XCode in 2019...). I'm using, CMake for build integration. Using the following directive in CMakeLists.txt fixed it for me:
我在使用 XCode 时发生了这种情况（我在 2019 年使用的是最新版本的 XCode ......）。我正在使用 CMake 进行构建集成。在 CMakeLists.txt 中使用以下指令为我修复了它：
set(CMAKE_CXX_STANDARD 14).
set(CMAKE_CXX_STANDARD 14).
Example:
例子：
cmake_minimum_required(VERSION 3.14.0)
set(CMAKE_CXX_STANDARD 14)
# Rest of your declarations...
回答by Aleksey Timoshchenko
In my caseI was needed update the std=c++
就我而言，我需要更新 std=c++
I mean in my gradle file was this
我的意思是在我的 gradle 文件中是这样的
android {
...
defaultConfig {
...
externalNativeBuild {
cmake {
cppFlags "-std=c++11", "-Wall"
arguments "-DANDROID_STL=c++_static",
"-DARCORE_LIBPATH=${arcore_libpath}/jni",
"-DARCORE_INCLUDE=${project.rootDir}/app/src/main/libs"
}
}
....
}
I changed this line
我改变了这条线
android {
...
defaultConfig {
...
externalNativeBuild {
cmake {
cppFlags "-std=c++17", "-Wall" <-- this number from 11 to 17 (or 14)
arguments "-DANDROID_STL=c++_static",
"-DARCORE_LIBPATH=${arcore_libpath}/jni",
"-DARCORE_INCLUDE=${project.rootDir}/app/src/main/libs"
}
}
....
}
That's it...
就是这样...
回答by Alex Cohn
If you are stuck with c++11, you can get make_uniquefrom abseil-cpp, an open source collection of C++ libraries drawn from Google's internal codebase.
如果您坚持使用c++11，则可以make_unique从abseil-cpp获取，这是一个从 Google 的内部代码库中提取的 C++ 库的开源集合。
