How to set the severity level of Boost log library-CodePudding

I have been successfully using the Boost Log library in my project. In other words, I am emitting log messages via BOOST_LOG_TRIVIAL(info) << "My message";

Now I want to control the severity of logging, and I followed the example from the Boost Log library documentation:

#include <boost/log/trivial.hpp>
#include <boost/log/core.hpp>

namespace logging = boost::log;

void init()
{
    logging::core::get()->set_filter
    (
        logging::trivial::severity >= logging::trivial::info
    );
}

However, I am getting this compilation error:

main.cpp:22:25: error: ‘severity’ is not a member of ‘boost::log::v2s_mt_posix::trivial’
   22 |       logging::trivial::severity >= logging::trivial::info

Here is the relevant section of my CMakeLists.txt:

SET(Boost_USE_STATIC_LIBS ON)
find_package(Boost 1.71 COMPONENTS log graph REQUIRED)
include_directories(${Boost_INCLUDE_DIRS})

add_executable(ls_router main.cpp)
target_link_libraries(ls_router PUBLIC ${Boost_LIBRARIES} pthread)

I am on Ubuntu and installed Boost via sudo apt install libboost-all-dev.

dpkg -l | grep libboost-log
ii  libboost-log-dev                       1.71.0.0ubuntu2                       amd64        C   logging library (default version)
ii  libboost-log1.71-dev                   1.71.0-6ubuntu6                       amd64        C   logging library
ii  libboost-log1.71.0                     1.71.0-6ubuntu6                       amd64        C   logging library

According to this SO question, this might be a CMake configuration issue. Boost.Log with CMake causing undefined reference error. However, none of the suggestions in the question solved my issue.

CodePudding user response：

The severity keyword is defined in boost/log/detail/trivial_keyword.hpp. Apparently it's not being included.

The minimal set of includes I could find:

#include <boost/log/core.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/expressions.hpp>

namespace logging = boost::log;

void init()
{
    logging::core::get()->set_filter(logging::trivial::severity >=
                                     logging::trivial::info);
}

int main() { init(); }

According to this SO question, this might be a CMake configuration issue

That's about linker errors, which this isn't.