我刚开始接触Mac电脑,正在尝试使用gcc 4.6。我已经安装了MacPorts并安装了gcc 4.6.1(通过执行
错误信息:
请注意,如果我使用虚拟异步函数,它可以正常编译和运行。我有些困惑,我需要安装特定的库(版本)吗?我该怎么做?
sudo port install gcc46
)。我正在尝试编译一段简单的测试代码,这段代码在Linux(使用gcc 4.6.1和4.6.2)和Windows上编译都很顺利,但是我收到了一些错误提示,让我认为安装的库有问题。#include <iostream>
#include <type_traits>
#include <future>
struct test {
void get() {}
};
/*template<typename Func>
test async(const Func &f) {
f();
return test();
}*/
using namespace std;
int main (int argc, const char * argv[])
{
auto t1 = async([]() -> int{
cout << "This is thread 1" << endl;
return 1;
});
auto t2 = async([]() -> int {
cout << "This is thread 2" << endl;
return 2;
});
std::cout << "This is the main thread" << endl;
t1.get();
t2.get();
return 0;
}
错误信息:
macbook01:Test fozi$ g++ main.cpp -o test -std=c++0x
main.cpp: In function 'int main(int, const char**)':
main.cpp:30:6: error: invalid use of incomplete type 'std::enable_if<true, std::future<int> >::type'
/opt/local/include/gcc46/c++/future:111:11: error: declaration of 'std::enable_if<true, std::future<int> >::type'
main.cpp:30:6: error: unable to deduce 'auto' from '<expression error>'
main.cpp:35:6: error: invalid use of incomplete type 'std::enable_if<true, std::future<int> >::type'
/opt/local/include/gcc46/c++/future:111:11: error: declaration of 'std::enable_if<true, std::future<int> >::type'
main.cpp:35:6: error: unable to deduce 'auto' from '<expression error>'
/opt/local/include/gcc46/c++/future: At global scope:
/opt/local/include/gcc46/c++/future:150:5: error: 'typename std::enable_if<(! std::is_same<typename std::decay<_Functor>::type, std::launch>::value), std::future<decltype (declval<_Fn>()((declval<_Args>)()...))> >::type std::async(_Fn&&, _Args&& ...) [with _Fn = main(int, const char**)::<lambda()>, _Args = {}, typename std::enable_if<(! std::is_same<typename std::decay<_Functor>::type, std::launch>::value), std::future<decltype (declval<_Fn>()((declval<_Args>)()...))> >::type = std::future<int>]', declared using local type 'main(int, const char**)::<lambda()>', is used but never defined [-fpermissive]
/opt/local/include/gcc46/c++/future:150:5: error: 'typename std::enable_if<(! std::is_same<typename std::decay<_Functor>::type, std::launch>::value), std::future<decltype (declval<_Fn>()((declval<_Args>)()...))> >::type std::async(_Fn&&, _Args&& ...) [with _Fn = main(int, const char**)::<lambda()>, _Args = {}, typename std::enable_if<(! std::is_same<typename std::decay<_Functor>::type, std::launch>::value), std::future<decltype (declval<_Fn>()((declval<_Args>)()...))> >::type = std::future<int>]', declared using local type 'main(int, const char**)::<lambda()>', is used but never defined [-fpermissive]
请注意,如果我使用虚拟异步函数,它可以正常编译和运行。我有些困惑,我需要安装特定的库(版本)吗?我该怎么做?