std ::线程在MacPorts gcc4.5 [英] std::thread in MacPorts gcc4.5

问题描述

我试图编译一些我在Linux上编写的软件，它在我的Mac上使用了一些新奇的C ++ 0x功能。我使用MacPorts来安装gcc45软件包，它给了我/opt/local/bin/g++-mp-4.5，但是这个编译器不想编译< thread> 。例如，我尝试编译：



  // test.cpp 
 #include< thread> 
 
 int main（）
 {
 std :: thread x; 
返回0; 
} 
  

并获得：



  bash-3.2 $ /opt/local/bin/g++-mp-4.5 -std = c ++ 0x test.cpp 
 test.cpp：In function'int main （）'：
 test.cpp：5：2：error：'thread'不是'std'的成员
 test.cpp：5：14：error：expected';'before'x '
  





快速查看/ opt / local / include / gcc45 / c ++ / ::线程类被定义，但由以下内容保护：

  #if defined（_GLIBCXX_HAS_GTHREADS）&&定义（_GLIBCXX_USE_C99_STDINT_TR1）
  

再一次，这在我的Ubuntu机器上完美运行，那么启用g ++ 4.5（g ++ - mp-4.5）的MacPorts版本下的c ++ 0x < thread> 库？如果没有，我需要知道什么（配置标志等），然后才开始编译gcc 4.5自己？

更新：
它看起来并不像SO社区对此有多少了解，所以现在是时候离开发商一点点了。有谁知道我可以将这个问题转发给官方邮件列表吗？是否有任何礼仪提示可以帮助我获得答案？

更新2：
我问过另一个临时解决方案这里，所以我现在只是用boost :: thread库替换std的人。不幸的是，没有boost :: future，所以这还不是一个完整的解决方案。任何帮助仍将不胜感激。

解决方案

实际上< thread> 库在Mac OS X下不起作用，因为这里的pthreads没有超时的函数（例如pthread_mutex_timedlock（））。此功能的可用性必须使用<$ 检查 c $ c> _POSIX_TIMEOUTS 宏，但在Mac OS X 10.4,10.5和10.6中定义为 -1 （我不知道10.7是什么）并且这个函数在 pthread.h中不存在。

$ b $ < _POSIX_TIMEOUTS

在配置libstdc ++期间检查code> macro。如果检查成功结束 _GLIBCXX_HAS_GTHREADS 宏定义。并且< thread> 内容可用于 -std = c ++ 0x 。

libstdc ++确实需要 _POSIX_TIMEOUTS eg在 std :: timed_mutex 类实现中（见< mutex> 标题）。

总之，当GCC的gthreads或libstdc ++将实现pthread_mutex_timedlock（）（以及其他）时，我认为< thread> ）模拟，或者这个函数将在Mac OS X中实现。

或者在未来的C ++标准中可能会有一种方法来查询语言功能（例如，这个定时函数和类），并且可以在禁用此功能的情况下构建libstdc ++。不过，我对未来的标准并不十分熟悉，并对此功能有所怀疑。

I'm trying to compile some software I've been writing in Linux that uses some fancy new C++0x features on my Mac. I used MacPorts to install the gcc45 package, which gave me /opt/local/bin/g++-mp-4.5, however this compiler doesn't want to compile anything in <thread>. Eg I try to compile:

//test.cpp
#include <thread>

int main()
{
std::thread x;
return 0;
}

and get:

bash-3.2$ /opt/local/bin/g++-mp-4.5 -std=c++0x test.cpp 
test.cpp: In function 'int main()':
test.cpp:5:2: error: 'thread' is not a member of 'std'
test.cpp:5:14: error: expected ';' before 'x'

A quick look in /opt/local/include/gcc45/c++/thread shows that the std::thread class is defined, but is guarded by the following:

#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)

Again, this works perfectly on my Ubuntu machine, so what's the proper way to enable the c++0x <thread> library under the MacPorts version of g++ 4.5 (g++-mp-4.5)? Failing that, is there anything I need to know (configure flags, etc.) before I go about compiling gcc 4.5 myself?

Update: It doesn't look like the SO community knows much about this, so maybe it's time to go a little closer to the developers. Does anyone know of an official mailing list I could forward this question to? Are there any etiquette tips to help me get an answer?

Update 2: I asked SO for another temporary solution here, and so I'm now just substituting the boost::thread libraries for the std ones. Unfortunately, there is no boost::future so this isn't quite a full solution yet. Any help would still be greatly appreciated.

解决方案

Actually <thread> library doesn't work under Mac OS X because pthreads here don't have some functions with timeouts (e.g. pthread_mutex_timedlock()). Availability of this functions have to be checked using _POSIX_TIMEOUTS macro but it's defined to -1 in Mac OS X 10.4, 10.5 and 10.6 (I don't know what's about 10.7) and this functions are really absent in pthread.h.

The _POSIX_TIMEOUTS macro is checked during the configuration of libstdc++. If the check ends successfully _GLIBCXX_HAS_GTHREADS macro becomes defined. And <thread> contents become available with -std=c++0x.

libstdc++ really needs _POSIX_TIMEOUTS e.g. in std::timed_mutex class implementation (see <mutex> header).

To summarize, I think that <thread> would become available on Mac OS X when GCC's gthreads or libstdc++ will implement pthread_mutex_timedlock() (and others) emulation or when this functions will be implemented in Mac OS X.

Or maybe there would be a way in the future C++ standard to query for language features (e.g. this timed functions and classes) and it will be possible to build libstdc++ with this features disabled. However I'm not very familiar with the future standard and have doubts about that feature.

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