the compiler throws an error on a function from boost.asio with cmake

Question

I'm just learning boost.asio and decided to try to learn how to work with cmake as well, but my IDE swears at the async_wait function

my code looks like this

#include <boost/asio.hpp>
#include <iostream>
#include <functional>

void print(boost::system::error_code& ec) {
    std::cout << "Hello\n";
}

int main() {
    boost::asio::io_context io;
    boost::asio::steady_timer t(io, boost::asio::chrono::seconds(1));

    t.async_wait(std::bind(print, boost::asio::placeholders::error));
}

but the compiler throws this error

E0304 missing instances of the "boost::asio" function template::basic_waitable_timer<Clock, WaitTraits, Executor>::async_wait [with Clock=std::chrono::steady_clock, WaitTraits=boost::asio::wait_traitsstd::chrono::steady_clock, Executor=boost::asio::any_io_executor]" corresponding to the list of arguments

maybe it's because I didn't connect CMakeLists correctly

cmake_minimum_required (VERSION 3.8)

 project ("BoostLer")

 set(BOOST_ROOT "C:\\boost")
 set(BOOST_LIBRARYDIR "${BOOST_ROOT}/lib")
 set(BOOST_INCLUDEDIR "${BOOST_ROOT}/include")

 find_package(boost REQUIRED COMPONENTS system filesystem)
 add_subdirectory("BoostLer")

This is the first CMakeLists

add_executable (BoostLer "BoostLer.cpp" )

 if (CMAKE_VERSION VERSION_GREATER 3.12)
   set_property(TARGET BoostLer PROPERTY CXX_STANDARD 20)
 endif()

 include_directories(${Boost_INCLUDE_DIRS})
 target_link_libraries(BoostLer PUBLIC ${BOOST_LIBRARIES})

this is the second CMakeLists

Answer 1

You're using the asio placeholder with std::bind. I think you need to use std::placeholders::_1 instead.

Of course you could use a lambda to avoid bind expressions in the first place.

Also, your program will not have any effect unless you run the io_context.

Answer 2

To further elaborate on sehe's answer

t.async_wait([](const boost::system::error_code ec)
    {
        // do something when timer times out
    }
);