making threads C2672 and C2893 error code ( c++ )

问题

I have trouble compiling this code i get the following messages :

C2672 'std::invoke': no matching overloaded function found

C2893 Failed to specialize function template 'unknown-type std::invoke(_Callable &&,_Types &&...) noexcept()'

    static auto f = [ ] ( int offset , int step , std::vector<Vert>& vertices , const Transform &transform ) {
        // do stuff
    };

    // create threads

    int max_threads = 4 ;
    std::thread **active_threads = new std::thread * [ max_threads + 1 ] ;

    for ( int i = 0 ; i < max_threads ; i++ )
        active_threads [ i ] = new std::thread ( f , i , max_threads , vertices , transform ) ;

and this gets the same error as well :

    int max_threads = 4 ;

    static auto f = [ ] ( Vert *verts , int offset , int step , const std::vector<Vert> &vertices , const Transform& transform ) {
        // do stuff
    }

    // create threads

    std::vector<std::thread> active_threads ;

    for ( int i = 0 ; i < max_threads ; i++ )
        active_threads.push_back ( std::thread ( f , verts , i , max_threads , vertices , transform ) ) ;

Compiler : the default vs2019 compiler

回答1:

I can't reproduce the error in VS2019 with C++14. I did however put the references in std::ref wrappers, but even without them I didn't get the same error (but a totally different).

My guess is that it's something else in your code that is causing the problem.

#include <iostream>
#include <list>
#include <thread>
#include <vector>

struct Vert {};
struct Transform {};

static auto f = [](int offset, int step, std::vector<Vert>& vertices,
                   const Transform& transform) {
    std::cout << offset << ' ' << step << ' ' << vertices.size() << '\n';
};

int main() {
    std::list<std::thread> active_threads;

    int max_threads = 4;
    std::vector<Vert> vertices;
    Transform transform;

    for(int i = 0; i < max_threads; i++)
        active_threads.emplace_back(f, i, max_threads, std::ref(vertices),
                                    std::ref(transform));

    for(auto& th : active_threads) {
        th.join();
    }
}

来源：https://stackoverflow.com/questions/60417178/making-threads-c2672-and-c2893-error-code-c

标签

c++

c++14