r/w test

#!/usr/bin/env sh

set -o errexit
set -o verbose

g++ -x c++ - -std=gnu++11 -pthread -o a <<__EOF && ./a && echo OK || echo failed!
#include <iostream>
#include <thread>
#include <limits>

#include <cstdint>
#include <cstdlib>

typedef std::uintmax_t T;

std::size_t const half_digits = std::numeric_limits< T >::digits / 2;
T const a = (std::numeric_limits< T >::max() << half_digits);
T const b = (std::numeric_limits< T >::max() >> half_digits);
volatile T x;

struct thread_flipper
{
    void operator () () const
    {
        for (;;) {
            x = a;
            x = b;
        }
    }
};

struct thread_checker
{
    void operator () () const
    {
        for (;;) {
            volatile auto const y = x;
            if ((y != a) && (y != b)) {
                std::cerr << "x read partitionally" << std::endl;
            }
        }
    }
};

int main()
{
    //std::cout << std::numeric_limits< decltype(x) >::digits << std::endl;
    //std::cin.get();
    x = a;
    std::thread t1((thread_flipper()));
    std::thread t2((thread_checker()));
    t1.join();
    t2.join();
    return EXIT_SUCCESS;
}
__EOF