#include <iostream>
#include <thread>
#include <future>
 
int main() {
    try {
        std::promise<void> p;
        auto f = p.get_future();
        std::thread{[p = std::move(p)] () mutable {
            // p.set_value(); // Imagine exception happens
        }}.detach();
        f.get();
    } catch (const std::future_error&) {
        // promise broken as expected.
        return 0;
    }
    std::cout << "Promise not broken?\n";
    return 1;
}

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