c++ 11 - passing member function to thread gives: no overloaded function takes 2 arguments

Question

From what I have looked up, my syntax is correct but my compiler (VS2015) is complaining. Note, I'm using namespace ee with the class Network. Here's the code

    //code that doens't work
    thread clientThread(&ee::Network::clientRun, new ee::Network);

*note: in the real code I'm not calling new as an argument, I did it here to shorten code.

I've tested the functions and they work, I just can't get them to work using thread. Here is their signatures.

    void serverRun();
    void clientRun();
    void clientRun(string ip);

My errors are:

1. Error C2661 'std::thread::thread': no overloaded function takes 2 arguments

2. abc no instance of constructor "std::thread::thread" matches the argument list

Does anyone have any insight as to what might be happening in this situation?

Answer 1

Ben's suggestion fixed my problem, but I'm not sure why.

The problem is with the first argument &ee::Network::clientRun . clientRun has 2 overloads, but at the point of template deduction (to deduce the types of the arguments to std::thread::thread<> ) the compiler is not yet in a position to distinguish which of the overloads is more valid.

Ben's solution worked because the cast prior to the call has done the compilers' work for it - by specifying the type of Network::clientRun to be void (ee::Network*)(void) rather than the equally valid void (ee::Network*)(string) .

Some examples:

#include <thread>
#include <string>

struct Network
{
  void clientRun();
  void clientRun(std::string);
};

int main()
{
  // not ok...
//  std::thread clientThread(&Network::clientRun, new Network);

  // ok - tells the compiler which overload
  auto member_function = static_cast<void (Network::*)()>(&Network::clientRun);
  std::thread clientThreadA(member_function, new Network);

  // also ok
  using call_type = void (Network::*)();
  std::thread clientThreadB(call_type(&Network::clientRun), new Network);
}