Why is there still no std::thread, std::promise and std::future in MinGW? And what's the alternative to promise and futures in win32?

So I've been trying to get the following code to compile and run on Windows by using a MinGW compiler.

#include <iostream>
#include <thread>
#include <future>

void ThreadWork(std::promise<int> &&p)
{
    // Pre-return from thread, do work after returning a value
    /* if else and things */ p.set_value(0);

    std::cout << "From thread" << std::endl;
    // More work
}

int main()
{
    std::promise<int> p;
    std::future<int> f = p.get_future();
    std::thread th(ThreadWork, std::move(p));

    // Get return value from thread
    int ret = f.get();
}

The above gives the error:

 error: aggregate 'std::promise<int> p' has incomplete type and cannot be defined
  75 |         std::promise<int> p;

error: variable 'std::future<int> f' has initializer but incomplete type
   76 |         std::future<int> f = p.get_future();

error: 'thread' is not a member of 'std'
   77 |         std::thread th(readInThread, callback, std::move(p));

Tried using official MinGW build, Tried using meganz/mingw-std-threads (that seem to throw errors like _WIN32_WININT is not set even though it is set to 0x0A00, if I try to set it manually compilation fails with redeclaration), and many more, succeed in none...

I also tried to link with pthreads: -lpthread no luck :(

Why are C++11 standard features still not implemented in MinGW? And what's the alternative for them currently?