io_service destructor hangs if serial_port read is queued, even if not running

[Martinho Fernandes <martinho.fernandes@…>]

The following program does not terminate.

#include <boost/asio.hpp>

int main() {
    auto* ios = new boost::asio::io_service;
    auto* port = new boost::asio::serial_port(*ios);
    port->open("COM6");
    char c;
    boost::asio::async_read(*port, boost::asio::buffer(&c, 1), [](boost::system::error_code, int) {});

    delete ios;
}

Despite the fact that the io_service is not running, its destructor hangs if there is a pending async_read from a serial_port. If that read completes (by receiving one byte), the program terminates.

[Martinho Fernandes <martinho.fernandes@…>]

Oh, I can only reproduce this on Windows.

[anonymous]

User error: objects dependent on an io_service should be destroyed prior to that io_service's destruction.