错误：没有用于调用 std::thread 的匹配函数

Question

I'm trying to run a function called dcp in a thread, I've to run this function three times independently. So here's how I'm implemented that:

void dcp(cv::Mat&, int, int, cv::Mat&, double);

int main(int argc, char* argv[])
{
cv::Mat IllumTrans;
//fill IllumTrans

std::vector<cv::Mat> rgbDCP;
rgbDCP.reserve(3);
//Fill it

std::thread thread_1(dcp, rgb[0], rows, cols, IllumTrans, A[0]);
std::thread thread_2(dcp, rgb[1], rows, cols, IllumTrans, A[1]);
std::thread thread_3(dcp, rgb[2], rows, cols, IllumTrans, A[2]);

thread_1.join();
thread_2.join();
thread_3.join();
}

But I get that error of no matching function for call:

In file included from 21022018WorksfineOneimageThread.cpp:6:0:
/usr/include/c++/7/thread: In instantiation of ‘struct std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >’:
/usr/include/c++/7/thread:127:22:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(cv::Mat&, int, int, cv::Mat&, double); _Args = {cv::Mat&, int&, int&, cv::Mat&, int&}]’
21022018WorksfineOneimageThread.cpp:136:65:   required from here
/usr/include/c++/7/thread:240:2: error: no matching function for call to ‘std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >::_M_invoke(std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >::_Indices)’
  operator()()
  ^~~~~~~~
/usr/include/c++/7/thread:231:4: note: candidate: template<long unsigned int ..._Ind> decltype (std::__invoke((_S_declval<_Ind>)()...)) std::thread::_Invoker<_Tuple>::_M_invoke(std::_Index_tuple<_Ind ...>) [with long unsigned int ..._Ind = {_Ind ...}; _Tuple = std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int>]
    _M_invoke(_Index_tuple<_Ind...>)
    ^~~~~~~~~
/usr/include/c++/7/thread:231:4: note:   template argument deduction/substitution failed:
/usr/include/c++/7/thread: In substitution of ‘template<long unsigned int ..._Ind> decltype (std::__invoke(_S_declval<_Ind>()...)) std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >::_M_invoke<_Ind ...>(std::_Index_tuple<_Ind1 ...>) [with long unsigned int ..._Ind = {0, 1, 2, 3, 4, 5}]’:
/usr/include/c++/7/thread:240:2:   required from ‘struct std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >’
/usr/include/c++/7/thread:127:22:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(cv::Mat&, int, int, cv::Mat&, double); _Args = {cv::Mat&, int&, int&, cv::Mat&, int&}]’
21022018WorksfineOneimageThread.cpp:136:65:   required from here
/usr/include/c++/7/thread:233:29: error: no matching function for call to ‘__invoke(std::__tuple_element_t<0, std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >, std::__tuple_element_t<1, std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >, std::__tuple_element_t<2, std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >, std::__tuple_element_t<3, std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >, std::__tuple_element_t<4, std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >, std::__tuple_element_t<5, std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >)’
    -> decltype(std::__invoke(_S_declval<_Ind>()...))
                ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/7/tuple:41:0,
                 from /usr/include/c++/7/functional:54,
                 from /usr/local/include/opencv2/core/utility.hpp:60,
                 from /usr/local/include/opencv2/core.hpp:3261,
                 from 21022018WorksfineOneimageThread.cpp:1:
/usr/include/c++/7/bits/invoke.h:89:5: note: candidate: template<class _Callable, class ... _Args> constexpr typename std::__invoke_result<_Functor, _ArgTypes>::type std::__invoke(_Callable&&, _Args&& ...)
     __invoke(_Callable&& __fn, _Args&&... __args)
     ^~~~~~~~
/usr/include/c++/7/bits/invoke.h:89:5: note:   template argument deduction/substitution failed:
/usr/include/c++/7/bits/invoke.h: In substitution of ‘template<class _Callable, class ... _Args> constexpr typename std::__invoke_result<_Functor, _ArgTypes>::type std::__invoke(_Callable&&, _Args&& ...) [with _Callable = void (*)(cv::Mat&, int, int, cv::Mat&, double); _Args = {cv::Mat, int, int, cv::Mat, int}]’:
/usr/include/c++/7/thread:233:29:   required by substitution of ‘template<long unsigned int ..._Ind> decltype (std::__invoke(_S_declval<_Ind>()...)) std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >::_M_invoke<_Ind ...>(std::_Index_tuple<_Ind1 ...>) [with long unsigned int ..._Ind = {0, 1, 2, 3, 4, 5}]’
/usr/include/c++/7/thread:240:2:   required from ‘struct std::thread::_Invoker<std::tuple<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int> >’
/usr/include/c++/7/thread:127:22:   required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(cv::Mat&, int, int, cv::Mat&, double); _Args = {cv::Mat&, int&, int&, cv::Mat&, int&}]’
21022018WorksfineOneimageThread.cpp:136:65:   required from here
/usr/include/c++/7/bits/invoke.h:89:5: error: no type named ‘type’ in ‘struct std::__invoke_result<void (*)(cv::Mat&, int, int, cv::Mat&, double), cv::Mat, int, int, cv::Mat, int>’

I'm compiling my program like that:

g++ -std=c++1z -fomit-frame-pointer -O3 -ffast-math -mmmx -msse -msse2 -msse3 -DNDEBUG -Wall 21022018WorksfineOneimageThread.cpp -o 21022018WorksfineOneimageThread -fopenmp `pkg-config --cflags --libs opencv`

gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3~16.04.1) 

Answer 1

您的函数需要一个引用（ cv::Mat& ）作为它的第一个和第四个参数，但您只传递cv::Mat ，因此您应该将它们包装在std::ref ：

std::thread thread_1(dcp, std::ref(rgb[0]), rows, cols, std::ref(IllumTrans), A[0]);

Answer 2

I'd like to point out something in case someone runs into the same problem as me.

I had a similar problem where I was launching a thread from within a const member function. The function that the thread was going to execute wasn't const because it needed to modify the member variables of the object that created it, but since the this pointer was const due to being called from a const function the compiler complained with an error similar to OP's.

I can't share my code but I'll share something similar to demonstrate the issue.

void FooClass::setup() const  // The const here was my problem
{
  // Here, the 'this' pointer is const due to the setup function being const
  // but the thread_routine function expects it no to be const.
  std::thread(&FooClass::thread_routine, this).detach();
}

void FooClass::thread_routine()
{
  // Do something with member variables
}

Hope this helps anyone in the future.