Problems with C++ threads

Question

Hello, I’m using mingw, 32-bit version in windows 7 Ultimate and I’m having trouble using threads.
I know they don’t work for this version of mingw, which is why I use the version in this link. But I don’t compile this example, because it says

In Static Member Function 'Static unsigned int mingw_stdthread::thread:_hardware_concurrency_helper()':

error: '::Getnativesysteminfo' has not been declared (in line 266)

This in the thread file I downloaded, tested on this site and worked this example, someone could tell me why this happens?

#include <iostream>         // std::cout
#include <thread>           // std::thread

class test {
public:
    static void foo(){}
    static void bar(int x){}
    test(){
         std::thread first (foo);     // spawn new thread that calls foo()
         std::thread second (bar,0);  // spawn new thread that calls bar(0)
         first.join();                // pauses until first finishes
         second.join();               // pauses until second finishes
    }
};

int main() {
     test TESTE;
     return 0;
}

Answer 1

There are many different distributions of Mingw, some do not support threads directly, and require the inclusion of platform-specific code. The page you posted contains these pieces of code, although the author states that he only tested it for Mingw-W64 5.3.0, and warns that platform detection macros can have to be adjusted manually for some versions of Windows.

The error you posted is related to a missing statement, you included the required library according to the instructions?

This is a header-only library. To use, just include the corresponding mingw.xxx. h file, Where xxx would be the name of the standard header that you would normally include.

You may need to declare, in the code on your platform:

#include mingw.thread.h
#include <thread>

If that’s not the problem, and you’re willing and able to use another distribution for Windows, which already contains built-in threads (recommend), here are some open options:

• TDM GCC, comes with GCC version 5.1.0 (very easy to install and use)
• Mingw-W64, comes with GCC 7.3