[Bug c++/92731] Data race on exception object thrown from std::future

[rrrlasse at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92731

--- Comment #4 from Lasse Reinhold <rrrlasse at hotmail dot com> ---
Some simplifications, and also tried with atomics instead of mutexes, to no
avail:

#include <iostream>
#include <stdexcept>
#include <future>
#include <assert.h>

std::function<void()> job;
std::atomic<bool> has_job{ false };

int main() {
    std::thread t = std::thread([]() {
        for (;;) {
            if (has_job.load(std::memory_order_acquire)) {
                job();
                has_job.store(false, std::memory_order_release);
            }
        }
    });

    for (int c = 0; ; c++) {
        if (!has_job.load(std::memory_order_acquire)) {
            try {
                std::packaged_task<void()> packaged_task([]() { throw 1234; });
                std::future<void> task_future = packaged_task.get_future();
                job = [&]() {
                    std::packaged_task<void ()> tmp(std::move(packaged_task));
                    tmp();
                };
                has_job.store(true, std::memory_order_release);
                task_future.get();
            }
            catch (const int& e) {
                assert(e == 1234);
            }
        }
    }
}